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Proprius Amp tweaking......

Printed From: Graham Slee Hifi System Components
Category: And the rest
Forum Name: Amplification
Forum Description: Share your interests or views on amplifiers, preamps, etc
URL: https://www.hifisystemcomponents.com/forum/forum_posts.asp?TID=2758
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Topic: Proprius Amp tweaking......
Posted By: ROMPerformance
Subject: Proprius Amp tweaking......
Date Posted: 07 Jan 2016 at 6:47pm
Can the output of these amps be raised at the factory without affecting sonic performance in any way shape or form. If so what is the max?

The reason i ask is because i'm now looking at decent speakers that are a good match for the Proprius.  I'm probably looking at around the £1000-£1500 shelf or stand mounted speakers.  I've been investigating Tannoy, ATC and B&W, they are all rated to handle 300w.  I was looking at Twenty's as well but they are at a higher price point than i want to go.  They are not for a big room either. 


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Francis :0)
Majestic DAC, Proprii, Solo ULDE, Voyager, Libran, Lautus, Spatia,, Cyrus CD XT SE2, Cyrus PSX-R, Sennheiser HD 800 and 540 Ref2, Harbeth SHL5



Replies:
Posted By: Richardl60
Date Posted: 07 Jan 2016 at 7:16pm
Yes this was a similar question I was looking to raise thank you. Can they be bridged? Whilst accepting they punch above their nominal ratings I have always been of the view that the more headroom the better and in theory the more ease and control over difficult loads they may bring?

Richard


Posted By: Graham Slee
Date Posted: 07 Jan 2016 at 8:52pm
A pair of Proprius were used for a music evening in a pub venue in the Midlands a few months ago. Unfortunately our roving reporter and my right hand man John C, forgot his camera, and neither did he post about it on here (naughty lad!Wink)

OK, they did use a pair of Klipschorns which are quite sensitive. I am told the event was packed but it was loud enough to get over the noise of the crowd. It was basically a disco using a disco front end with a quality mixer.

John C did comment however that on leaving the venue quite late, the sound could be heard from the car park across the road at a volume fitting for a disco.

Attendees commented on the good quality of the sound and the organisers have asked to use the pair of Proprius again. By the way, the phono preamps used were a pair of Gram Amp 2 SE which the organisers had bought.

So, are they going to be loud enough?

Just because the speakers have a rating of 300 watts does not mean they need 300 watts.

On our two own events (which we invited everybody to but only 30-40 turned up) we demonstrated that 25 watts per channel (real rms) could drive the relatively inefficient 11 Ohm LS35A speakers to a really healthy volume with excellent sound quality in hotel conference rooms much larger than the usual domestic living room.

But, even after saying all that, I guess people may not be convinced.

To bridge Proprius amps requires a balanced feed. One phase and screen is taken to one amp's input. The opposite phase and screen is taken to the other amp's input. The speaker "pos" is taken to the red terminal on the amp with the positive phase input. The speaker "neg" is taken to the red terminal on the amp with the other input.

The Majestic will provide the balanced feed.

The analyser measured a continuous 90 watts into 8 Ohms. The amps were just warm to the touch.


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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: Gary
Date Posted: 07 Jan 2016 at 9:21pm
I've been using Proprius amps with PMC Twenty 23's for a while now and I'm very happy with them. The amps were an upgrade from a pair of Audiolab 8200MB's rated at 250 watts. The Proprius very convincingly outperform the 8200MB, the biggest suprise for me was how much of an improvement there was with bass control, depth and detail.

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Solo ULDE, CuSat50, Spatia Links


Posted By: ICL1P
Date Posted: 07 Jan 2016 at 10:39pm
Originally posted by Gary Gary wrote:

I've been using Proprius amps with PMC Twenty 23's for a while now and I'm very happy with them. The amps were an upgrade from a pair of Audiolab 8200MB's rated at 250 watts. The Proprius very convincingly outperform the 8200MB, the biggest suprise for me was how much of an improvement there was with bass control, depth and detail.

That's a quote worth putting on the Proprius webpage.

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Ifor
=====
Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair.


Posted By: ROMPerformance
Date Posted: 07 Jan 2016 at 11:15pm
Many thanks for the input Mr.Slee, very honoured to have you reply to my post.  I guess however that means no to upping the output, OK, fair enough.  I might try bi-amping then but that will require 4 x Proprius amps.  Driving disco speakers is something else though.  Getting expensive now, and there's the Maj DAC i want, and one of those Voyagers i really fancy, and the speakers and CD player.  The whole in my pocket is getting pretty big now, Gawd elp me!

BTW... The ULDE i purchased from you back end of Novermber is starting to really perform and it sounds like it's getting louder. It's been plugged in 24/7 since the day it came nearly 6 wks ago and in the last few days or so the sound has started to noticeably richen, and it's a lot warmer sounding than when i first had it. Equally, it doesn't take so long to kind of get going once music is playing.  I look forward to hearing the sound evolve over a few more weeks.  

Gary, Great review, Twenty 23s, i'm jealous, many thanks for the comments, they must be pretty capable amps, and with great quality i bet.

I feel very encouraged by all your comments, to go out and buy whatever speakers i like, without worrying about driving them or how they will sound.  That's one complication i don't have to stress over. 

Life is better when it's simpler.

Ta very much :D  



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Francis :0)
Majestic DAC, Proprii, Solo ULDE, Voyager, Libran, Lautus, Spatia,, Cyrus CD XT SE2, Cyrus PSX-R, Sennheiser HD 800 and 540 Ref2, Harbeth SHL5


Posted By: JamesD
Date Posted: 08 Jan 2016 at 6:59am
Provided that the amp has good control over the speakers then I can't see the need for high wattage amplifiers. As with other parameters, manufacturers use ever higher (or lower) numbers to tempt buyers. I have an amp from the sixties that has a 30 watt rating that seldom needs to have its volume knob beyond 9 o'clock.

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Aren't ears brilliant


Posted By: BackinBlack
Date Posted: 08 Jan 2016 at 7:41am
I would suggest that you try just your single pair of Proprius first. I have used them in the past with supposedly power hungry loudspeakers and found them to be more than adequate in volume and control of the speakers, good tight bass with remarkable low extension and that smooth treble Graham manages to design into all his products.


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Just listen, if it sounds good to you, enjoy it.


Posted By: morris_minor
Date Posted: 08 Jan 2016 at 8:26am
Originally posted by Gary Gary wrote:

I've been using Proprius amps with PMC Twenty 23's for a while now and I'm very happy with them. The amps were an upgrade from a pair of Audiolab 8200MB's rated at 250 watts. The Proprius very convincingly outperform the 8200MB, the biggest suprise for me was how much of an improvement there was with bass control, depth and detail.
My Proprii drive a pair of PMC Gb1i speakers, and forum member msphil uses his with PMC Fact 8s. It should be remembered that the Proprius' 25 watts are "Yorkshire Watts" and thus in a different league to lesser watts . . Wink

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Bob

Majestic DAC/pre-amp
Accession MC/Enigma, Accession MM, Reflex M, Elevator EXP, Era Gold V
Solo ULDE, Novo, Lautus USB and digital, Libran balanced, CuSat50
2 x Proprius + Spatia/Spatia Links


Posted By: Aussie Mick
Date Posted: 08 Jan 2016 at 1:13pm
Plus one for "don't worry about power". My Proprii drive the Australian built Noteperfect Ovation speakers. Many people use them with 100-150w of valve or solid state amplification to excellent effect. However, one of the amps I tested at home before purchasing the Maj/Pro duo was the L***a T****a integrated. It sounded wonderful. The Slee combo sounded just as wonderful but more open (wide open!), half the price, and more flexible. Kept just as good control over the crossoverless midrange driver as the 150w beast. But, better texture and more nimble. It's a falsehood to say a watt is a watt is a watt.
Mick.

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Rega RP8 - Apheta 2 - Accession MC Enigma PS -Solo ULDE (Focal Utopia) - PS Audio M700 - Fical Kanta No2


Posted By: msphil
Date Posted: 08 Jan 2016 at 1:52pm
I can testify to the power and quality of the Proprius amps. I have used them with a pair of Mission 753 speakers as well as the wonderful PMC Fact 8 speakers. Both sets of speakers sound fantastic and as far as sound volume is concerned can knock the roof of your house! I haven't yet been able to turn them up beyond half volume! In my opinion, and a PMC dealer who heard them, they are fantastic amps especially when played using a Majestic DAC/preamp! The PMC dealer said that my system sounded better than the one that they use for demonstrations. Their system costs over £10,000 for each item. Conservatively I would guess it adds up to over £30,000-£40,000!

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'You are, through your soul not your body, a human being.'


Posted By: Fatmangolf
Date Posted: 08 Jan 2016 at 6:41pm
Hi Francis, you're already tuned into the message but I must belatedly add my bit about driving a variety of speakers including Monitor Audio GX100 (120 Watts 88dB/W) and GX300 (can handle 200 Watts 90dB/W), Acoustic Energy AE505's (100 Watts I think and 86dB/Watt) with the Proprius amps at levels from a whisper to a scream, to use a cliche.

I usually listen at relatively low levels 60-70dBA but have run each of these continuously at 100dBA (slow response) with undistorted (but very loud ) music in my living room. There was plenty of headroom and the amps running warm to the touch. When I trialled the Proprius against the CA 840A v2, a huge powerful amp of 2 x 200W, it was more open and the Proprius bass was deeper and firmer with the AE505's and GX100's I had available at the time.

@Bob, I love the idea of the Yorkshire Watt.

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Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.


Posted By: BAK
Date Posted: 09 Jan 2016 at 4:22pm
Originally posted by Graham Slee Graham Slee wrote:

A pair of Proprius were used for a music evening in a pub venue in the Midlands a few months ago.
OK, they did use a pair of Klipschorns which are quite sensitive. I am told the event was packed but it was loud enough to get over the noise of the crowd. It was basically a disco using a disco front end with a quality mixer.

John C did comment however that on leaving the venue quite late, the sound could be heard from the car park across the road at a volume fitting for a disco.

Attendees commented on the good quality of the sound and the organisers have asked to use the pair of Proprius again. By the way, the phono preamps used were a pair of Gram Amp 2 SE which the organisers had bought.

So, are they going to be loud enough?

Just because the speakers have a rating of 300 watts does not mean they need 300 watts.

On our two own events (which we invited everybody to but only 30-40 turned up) we demonstrated that 25 watts per channel (real rms) could drive the relatively inefficient 11 Ohm LS35A speakers to a really healthy volume with excellent sound quality in hotel conference rooms much larger than the usual domestic living room.

But, even after saying all that, I guess people may not be convinced.

 Any quality-built amplifier (like the Proprius) with greater than 20 watts rms power output is sufficient enough to drive speakers available today with very pleasing results.
 (By quality-built I mean: one that has enough current and voltage "headroom" designed-in, wide enough frequency response to not hinder delicate or powerfull sound passages, and extremely low distortion measurements at loud and quiet sound levels.)

The Proprius amplifiers can produce 26 watts rms driving into an 8 ohm speaker load... rms = rout-mean-square (another mathematical term for average power).
 That same rms power can be as much as 52 watts peak power, or more, even 70 watts instantaneous. That is the solid state circuit doing it's best into 8 ohms.
When driving into 4 ohms it will be almost 2 X as much!

Note that the 11 Ohm LS35A speakers are not that low in efficiency at 88dB @ 1 watt/1.5 meters, and the Klipschorns mentioned above are very high in efficiency  at about 95+ dB @ 1 watt/1 meter ( maybe as much as 98 dB!).
 That means with the same 1 watt input the Klipschorns would be about 10 dB louder!

Your speakers own sensitivity to the power applied to it will tell you how loud that speaker will be at a given power level (not how powerful your amp is).
 If your speakers can handle 50 watts rms and you drive them with 100 watts rms, you can easily burn out your speakers! even at half volume! First to go will be the tweeters.

 I always rate my speakers to handle 2 X the RMS power or more of the amplifier I intend to connect them to.
 And then I want to get speakers with as high an efficiency as possible.

I currently have some speakers rated at 200 watts rms connected to my 60 watt rms amplifier; these speakers have an efficiency of 96 dB @ 1 watt/1 meter.
And they get very loud at just 1 watt... the neighbors complain loud!
I have to keep the volume down to less than 1/2 watt to keep the peace.

See my next post for info about decibel levels and how to approximate decibels at different power levels.



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Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!


Posted By: BAK
Date Posted: 09 Jan 2016 at 4:44pm
Efficiency is more important than power handling for sound quality.
It is a matter of physics.
Every time a quantity of energy is transformed from one energy form to another there is a loss of energy. The loss can be quantified by measuring the efficiency of the transformation.
With a lower efficiency transformation, less of the original information from the energy source is reproduced in the end result.
 This amounts to less of the original sound energy is reproduced in lower efficiency speakers.

The dissertation below will prove that any quality-built amplifier (like the Proprius) with greater than 20 watts rms power output is sufficient enough to drive speakers available today with very pleasing results.

 (By quality-built I mean: one that has enough current and voltage "headroom" designed-in, wide enough frequency response to not hinder delicate or powerfull sound passages, and extremely low distortion measurements at loud and quiet sound levels.)

A little-known fact is:
 In old-school electronics,
less than 1 watt rms = low power,
from 1 watt to 10 watts = medium power,
greater than 10 watts rms = HIGH POWER...(100 watts rms is extra high but was not mentioned in the reference)

This rating scheme came from early radio days.
 It was found that less than 1 watt rms was all that was needed for "personal" listening; with  headphones or a pocket radio.
 1 watt to 10 watts was needed to fill the average room with sound as with a table radio (most were between 1.5 and 5 watts).
 Greater than 10 watts rms was only needed to fill large rooms.

Average commercial speaker sensitivity today is about 85 dB @ 1 watt rms measured @ 1 meter, in short form...85 dB @ 1 w/1m. That means that you get 85 dB at 1 watt when measured with a sound pressure measurement instrument with a calibrated microphone from a distance of 1 meter directly in front of the speaker, in the center of the speaker's radiating pattern...or straight in front.

 The below is a way to approximate decibel levels.

Now with acoustic power you add 10 dB for every multiple of 10 watts rms... or each time you multiply the power by 10.
 If with 1 watt you get 85 dB,
 then at 10 watts you get 95 dB,
 at 100 watts you will get 105 dB!
Again with acoustic power you add 3 dB for every multiple of 2
watts rms... or each time you multiply the power by 2.
 If with 1 watt you get 85 dB,
 then at 2 watts you get 88 db (+3 dB),
 at 4 watts you get 91 dB (+3 dB),
  and at 8 watts you get 94 dB (+3 dB),

 from above, at 10 watts you get 95 dB,
 then at 20 watts you get 98 dB (+3 dB).

If you have an 8 ohm speaker capable of producing 95 dB @ 1w/1m,
 you will get 105 dB @ 10 watts / 1m,
 and then 108 dB @ 20 watts / 1m,
 and about 110 dB @ 26 watts / 1m (Proprius power @ 8 ohms),
 and 115 dB @ 100 watts / 1m.

You see from above that, if you have a higher efficiency speaker, you will get more sound measured in decibels at any
acoustic power level than you will from a lower efficiency speaker.
You will also be able to drive the higher efficiency speaker with less power to get the same amount of sound!

This is why professional sound systems use very high efficiency speaker drivers.


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Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!


Posted By: ROMPerformance
Date Posted: 09 Jan 2016 at 4:47pm
Jon - Many thanks for your comments, they certainly add weight to the Proprius 25W of high quality output being more than the sum of it's parts.  Enough to drive most speakers and still have quality and performance, that does it for me and has put my mind at ease about what speakers to buy hence the choices i'm about to make.

BAK - Many thanks for what you've posted, i found it really useful.

Opinions would be gratefully accepted on the following speakers....

ATC SCM 11 or 19 Shelf/standmount

PMC Twenty 21 (Shelf/standmount)

Cheers




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Francis :0)
Majestic DAC, Proprii, Solo ULDE, Voyager, Libran, Lautus, Spatia,, Cyrus CD XT SE2, Cyrus PSX-R, Sennheiser HD 800 and 540 Ref2, Harbeth SHL5


Posted By: LOINER
Date Posted: 09 Jan 2016 at 5:28pm
Originally posted by ROMPerformance ROMPerformance wrote:



Opinions would be gratefully accepted on the following speakers....

heers


The only opinion that counts is your own.You are the one that is going to have to live with whatever you buy .Trust your ears.


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STUART
SOLO ULTRA LINEAR DIAMOND EDITION
LAUTUS DUAL MONO 1.5M INTERCONNECTS
GRAM AMP 2SE


Posted By: DaveG
Date Posted: 09 Jan 2016 at 5:49pm
I haven't heard those exact models but I have heard the twenty.22 which I thought were really verygood. If the house sound carries through to the 21's then they could be a good choice.

I've been curious to try ATC's for ages, but never got round to it. The only experience I have is of their big Pro monitors which I rated very highly back in the day. I believe they are a bit less efficient than average & benefit from a bit of welly.

You also mentioned Tannoys & B&W's in an earlier post. I've owned several pairs of Tannoys (M15's were part of my first proper hi-fi) and I've always liked the marque, usually quite high efficiency & easy to drive. I currently use B&W CM6 s2 which I am rather enjoying, they work well in my fairly small listening room. Took forever to run in though. All are worth a listen.

Definitely audition, preferably with your Proprius (pop them in your pocket, no problem Wink). But beyond that, when you think you have a winner - make your dealer let you take the demo pair home for the weekend (or longer). It's a bit of a faff but imo speaker/room interaction has a far greater impact on SQ than almost anything. In fact I'd go as far as to say a lot of the audiophile tweakery that goes on is a band aid to cover/repair failure to get the fundamentals right. And, yep I've done it wrong loads of times. Slow learner I guess Big smile


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Dave

Michell Gorbe + HR PSU -> Cadenza Bronze -> SME V -> Elevator -> Accession -> Proprius -> B&W CM6 s2 | Cusat 50 & Spatia cables ->


Posted By: ICL1P
Date Posted: 09 Jan 2016 at 6:15pm
Originally posted by ROMPerformance ROMPerformance wrote:


Opinions would be gratefully accepted on the following speakers....


If you fancy a bit of DIY, I keep coming across very favourable comments about IPL Acoustics kits, which can also be purchased fully built from e.g. IQ Speakers.


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Ifor
=====
Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair.


Posted By: ROMPerformance
Date Posted: 09 Jan 2016 at 6:17pm
Stuart, 

I understand that and you're absolutely right, however, if i had the time and energy to audition everything it would take forever and it would be quite an undertaking in itself.  Unfortunately i don't have that kind of time, nor the energy and inclination to do that therefore i have to put my faith in the fact i value respected industry reviews from well known and not so well known sources, and from actual owners reviews and opinions.

I do a lot of this and it serves me really well, maybe i'm just lucky.  

There are lots of people on this forum with much more experience than me, better tuned hearing etc..., listening to music on high end gear of all persuasions and prices.  I like to think you guys generally have really good ears and like myself not just love music but equally as important, care about how it sounds.

I don't see the point of joining a forum, specially one like this, if you don't also use it as both a technical resource and well of sonically educated opinions and advice based on users with years of experience. That counts for a lot in my book.

I take everything i read and hear, weigh it all up, juggle it for a bit and go from there, specially when it comes to spending money.  

I'm think doing ok so far with the choices of equipment i've made, despite not listening to any of it. 

If anyone thinks there are better choices from a sound or component matching viewpoint, using gear that matches well with GSP kit then i am really keen to hear more.  I haven't spent any money, yet, so i'm still open to ideas although that will start to change Monday first thing.

Hopefully my luck will not run out, just yet.




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Francis :0)
Majestic DAC, Proprii, Solo ULDE, Voyager, Libran, Lautus, Spatia,, Cyrus CD XT SE2, Cyrus PSX-R, Sennheiser HD 800 and 540 Ref2, Harbeth SHL5


Posted By: ROMPerformance
Date Posted: 09 Jan 2016 at 6:57pm
Ifor,

I quite like left field choices, interesting option but very few reviews of any kind on these speakers.  

Just looking at Harbeth too.  Interestingly they come across as being the GSP audio of the speaker world. Small independent and highly successful manufacturer of the finest quality sound reproduction equipment money can buy.  Those Harbeth look very good indeed. 



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Francis :0)
Majestic DAC, Proprii, Solo ULDE, Voyager, Libran, Lautus, Spatia,, Cyrus CD XT SE2, Cyrus PSX-R, Sennheiser HD 800 and 540 Ref2, Harbeth SHL5


Posted By: ICL1P
Date Posted: 09 Jan 2016 at 7:21pm
Originally posted by ROMPerformance ROMPerformance wrote:

Ifor,

I quite like left field choices, interesting option but very few reviews of any kind on these speakers.  

Just looking at Harbeth too.  Interestingly they come across as being the GSP audio of the speaker world. Small independent and highly successful manufacturer of the finest quality sound reproduction equipment money can buy.  Those Harbeth look very good indeed. 


No, because they're kits you won't find many reviews in the main stream, but if you delve into other fora you should find some genuine user experiences. I've read some posts by guys who have replaced both Harbeths and very expensive PMCs with IPLs.

I plan to build some in the not too distant future.

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Ifor
=====
Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair.


Posted By: LOINER
Date Posted: 09 Jan 2016 at 7:46pm
Francis
           Thank you for your polite reply,and yes I take your point re trapesing round dealers and you can guarantee that no one dealer will stock all the models that you want to listen to no matter how short your list is. I would suggest you have been extremely lucky.Lets hope your luck doesn't run out.


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STUART
SOLO ULTRA LINEAR DIAMOND EDITION
LAUTUS DUAL MONO 1.5M INTERCONNECTS
GRAM AMP 2SE


Posted By: ROMPerformance
Date Posted: 09 Jan 2016 at 8:03pm
Haha...  I'm always polite, most of the time. 

Whilst i appreciate one of these days i might come unstuck i put everything down to experience, good or bad.  You don't get better at doing stuff without making a few mistakes along the way. 

Fingers crossed


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Francis :0)
Majestic DAC, Proprii, Solo ULDE, Voyager, Libran, Lautus, Spatia,, Cyrus CD XT SE2, Cyrus PSX-R, Sennheiser HD 800 and 540 Ref2, Harbeth SHL5


Posted By: Richardl60
Date Posted: 09 Jan 2016 at 8:06pm
I must admit I thought that matching a speakers power handling and amps power delivery died out in the 70s?

I am sure my amp probably will double the nominal speaker power handling but has never caused me any issues, I would rather have good clean power delivery than risk driving to clipping the amp? I don't buy a car that will only do 70mph, I drive both sensibly and are happy with ample power reserves in both cases.

Surely the aim is to have the best amp/speaker combination SOUND or am I missing something?

Taking the point on highly efficient pro gear - concert, disco or PA yes otherwise not necessarily?

Whilst PMC has been raised if you look at one of their top PROFESSIONAL models I think the suggested amp ratings something like 250-950 wpc? Efficiency is quite high at 91db/w? I would have no issue or concerns with driving my speakers with a monster Bryston if the sound was top drawer and I had deeper pockets but would probably invest in some new speakers also!

I do thing it is too easy to become too embroiled in power and specs . . .

Richard


Posted By: Graham Slee
Date Posted: 09 Jan 2016 at 8:49pm
So is the Bryston what you'd recommend?


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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: Richardl60
Date Posted: 10 Jan 2016 at 6:03pm
No I was using this to illustrate a point re a very high power amp Graham - particularly as they have a link with PMC who had already been raised in the earlier discussions and I am aware the top models are extremely high power.

I would like to try one in the same way I would like to try many exotica as I would with an Aston Martin or a night in the Ritz.

Richard


Posted By: Richardl60
Date Posted: 10 Jan 2016 at 6:12pm
Ps I think this post was entered on the wrong entry (by me) I started typing and lost it so started again, this was intended to follow the observations about the power handling of speakers . . .

Richard


Posted By: BAK
Date Posted: 10 Jan 2016 at 7:26pm
[QUOTE=Richardl60]I must admit I thought that matching a speakers power handling and amps power delivery died out in the 70s?
/QUOTE]
 That is the impression most consumers have. Not true.
The mainstream media have been promoting "more is better", that is all that is.

Raw RMS specified power is not magic, it is true power that is not to be taken lightly...
 it can even be as destructive as the AC mains... 746 Watts RMS = 1 Horsepower.
That is 3.4 Amps @ 220 Volts ... 6.21 Amps @ 120 Volts.

"Surely the aim is to have the best amp/speaker combination SOUND or am I missing something?"
 Answer: An amplifier that has enough current and voltage "headroom" designed-in and a speaker that can handle the power, even the peaks, without burning out.
Some high power amplifiers have very little
current and voltage "headroom" designed-in.
Even some of the big names are very "headroom" poor.

Current "headroom" allows the transistors to deliver current to the speakers many times more than would be actually used, to keep the transistors from running out of current carrying capability and keep
them cool.

Voltage "headroom" is where the power supply voltage applied to the amplifier output circuit is many times more than the output voltage will "swing" from peak to peak.

 More power does not give more control over the sound energy delivered, nor does it provide better clean power delivery, or avoid the risk of driving the amp
to clipping.

The only way to prevent
driving the amp to clipping is to not overdrive its input.
It is a "WYSIWYG"... what you see is what you get...
WHAT YOU PUT IN IS WHAT YOU GET OUT.


Any quality-built amplifier (like the Proprius) with greater than 20 watts rms power output is sufficient enough to drive speakers available today with very pleasing results. This is stated for the common sized
house listening room. But even 26 Watts RMS driving 85 dB @1w/1m sensitive speakers can fill the average church hall with sound and even an average disco hall.
 (By quality-built I mean: one that has enough current and voltage "headroom" designed-in, wide enough frequency response to not hinder delicate or powerfull sound passages, and extremely low distortion measurements at loud and quiet sound levels.)

If I had to learn the above facts to keep from blowing speakers with too much power,
 I feel others can learn from my hard-earned experience.

Try testing a 200 Watt RMS guitar amplifier you just repaired with a 50 Watt capable speaker... POOF ! the speaker turns into flames and you get a lot of smoke! I had to buy a very expensive speaker for my customer... it was his speaker.
His 2 each, 100 Watt
speaker cabinets worked fine after the 50 Watt speaker fiasco.

 I strive to build or repair everything to last. My Dynaco ST120a (60 Watts RMS per channel with 1.5 volt peak input), circa 1973, is still running "in-use" today... 43 years later. I did rebuild it in 1996 with all new
medical grade 1% or better tolerance parts.


-------------
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!


Posted By: ROMPerformance
Date Posted: 10 Jan 2016 at 7:58pm
The listening environment is a room 3.9Mtrs x 3.0Mtrs.  The wall in front of me is 3Mtrs away, the bay window is to my right.  

It's not a big room.  I don't need big power, i need big quality, however, you know when you get a bit of music  or an artist that you particularly like a bit louder, sound with with more oomph and impact, and also times when you still like a bit of that impact even when at low listening levels.  

I think ultimately that comes down to quality over quantity,  and that's all i'm after.  I'm trying to do it as right first time as i can under the circumstances, hence why i value all your opinions and arguments. 

I love my music, i sing along, bop along in my chair, bounce around the house sometimes, however, it's as important how it sounds,  it doesn't need to be so loud my windows are flexing in and out,  i just want to be that little step closer to those angelic sounds. 


-------------
Francis :0)
Majestic DAC, Proprii, Solo ULDE, Voyager, Libran, Lautus, Spatia,, Cyrus CD XT SE2, Cyrus PSX-R, Sennheiser HD 800 and 540 Ref2, Harbeth SHL5


Posted By: BAK
Date Posted: 10 Jan 2016 at 8:19pm
Originally posted by Richardl60 Richardl60 wrote:


Whilst PMC has been raised if you look at one of their top PROFESSIONAL models I think the suggested amp ratings something like 250-950 wpc? Efficiency is quite high at 91db/w? I would have no issue or concerns with driving my speakers with a monster Bryston if the sound was top drawer and I had deeper pockets but would probably invest in some new speakers also!

I do thing it is too easy to become too embroiled in power and specs . . .
Richard

From PMC website,
http://pmc-speakers.com/products/professional/passive/mb2s-xbd - http://pmc-speakers.com/products/professional/passive/mb2s-xbd
specs on their MB2S XBD model:

Amplifier Power per Channel:       HF 120W , MF 120W , LF 600W, LF 600W
Available Finishes:                          Neo Black
Crossover Frequency:                    380Hz & 3.8kHz
Dimensions:                                    H 1740mm 68.50" W 380mm 14.96" D 535mm 21.06"
Drive Units:            LF x 2 310mm PMC Radial™ driver, MF 75mm PMC fabric dome , HF 34mm PMC soft dome
Effective ATL™ Length:                   2 x 3m 10ft
Impedance:                                      4 Ohm nominal
Input Connectors:                           3 Pairs 4mm Sockets (Tri-wire or Tri-amp)
Recommended Amp Power:        250-900W
Sensitivity:                                         91dB 1W 1m
Useable Frequency Response:   20Hz-25kHz Peak SPL @ 1M 124dB
Weight:                                               88kgs 193.6lbs

The PMC professional model MB2S XBD specs above:
 employs: 2 woofers (LF) rated @ 600 Watts, this is not stated whether this is PEAK power or RMS power;
               1 midrange (MF) rated @ 120 Watts;
                   1 tweeter (HF) rated @ 120 Watts.
When power is specified this way, it is only safe to believe it is a PEAK power rating, unless one gets a guarantee from the manufacturer that the speakers would not be burned out by applying the power they recommend.
 RMS power would be 0.707 times PEAK power. 600 Wpeak X 0.707 = 424 Wrms .
                                                                                        120 Wpeak X 0.707 = 85 Wrms

"Input Connectors:                           3 Pairs 4mm Sockets (Tri-wire or Tri-amp)"
 The separate driver connections indicate either an external Passive Crossover or separate power amplifiers are required.

The professional installer would know to limit the power delivered to these speakers to avoid blowing them.
 Don not be fooled by "recommended power", you may find you can not turn up the volume even half way where all volume controls start to sound best.


-------------
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!


Posted By: BAK
Date Posted: 10 Jan 2016 at 8:35pm
Originally posted by ROMPerformance ROMPerformance wrote:

The listening environment is a room 3.9Mtrs x 3.0Mtrs.  The wall in front of me is 3Mtrs away, the bay window is to my right.  

It's not a big room.  I don't need big power, i need big quality, however, you know when you get a bit of music  or an artist that you particularly like a bit louder, sound with with more oomph and impact, and also times when you still like a bit of that impact even when at low listening levels.  

I think ultimately that comes down to quality over quantity,  and that's all i'm after.  I'm trying to do it as right first time as i can under the circumstances, hence why i value all your opinions and arguments. 

I love my music, i sing along, bop along in my chair, bounce around the house sometimes, however, it's as important how it sounds,  it doesn't need to be so loud my windows are flexing in and out,  i just want to be that little step closer to those angelic sounds. 

Francis,
 In this room of 3.9Mtrs x 3.0Mtrs, for best bass response, put the speakers on the narrower wall. This would give the speaker's bass projected the longer distance to travel before bouncing of the opposite wall.
 Do I picture your room correctly... the bay window is on the narrower wall?
If so, speakers located on that wall or the opposite wall would be best.
On the wall opposite the bay window would give the advantage of opening the window to project the music outside!


-------------
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!


Posted By: Fatmangolf
Date Posted: 10 Jan 2016 at 9:30pm
The room I did my SPL measurements in is similar in dimensions to yours Francis. Bruce's points about speaker positioning to manage the room's acoustic properties are right.


-------------
Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.


Posted By: Richardl60
Date Posted: 10 Jan 2016 at 10:08pm
Three final observations:

I would never dream of feeding a guitar amp or anything other than that intended through my speakers, that is a recipe for disaster.

I am sure you will be aware that the relationship of where your preamp volume control is has little relation to the available power reserves as this will depend on a number of variables including matching or source to pre-amp, pre-power amp matching and indeed the level of the recording.

It appears acknowledged that the power figures specs from speaker manufacturers are sufficiently vague to render them rather meaningless anyway!

Richard


Posted By: BAK
Date Posted: 10 Jan 2016 at 11:01pm
Originally posted by Richardl60 Richardl60 wrote:

Three final observations:

I would never dream of feeding a guitar amp or anything other than that intended through my speakers, that is a recipe for disaster.

I am sure you will be aware that the relationship of where your preamp volume control is has little relation to the available power reserves as this will depend on a number of variables including matching or source to pre-amp, pre-power amp matching and indeed the level of the recording.

It appears acknowledged that the power figures specs from speaker manufacturers are sufficiently vague to render them rather meaningless anyway!

Richard

The guitar amp fiasco was a description of a learning experience I had. You must have missed that point.

I can name speaker manufacturers that do list complete specifications.
 look at this one made in Spain... http://www.beyma.com/products/coaxials/115XA38ND8 - http://www.beyma.com/products/coaxials/115XA38ND8
This 15" coaxial speaker would be great for any use when put in an appropriate cabinet.
And you could fill your home with sound using only1/10th Watt RMS (0.1w) per channel... they are rated at 99 dB @ 1w/1m.
 At 0.1w that would produce about 89 dB !




-------------
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!


Posted By: Graham Slee
Date Posted: 11 Jan 2016 at 1:51am
Monster amps get their name not just because of their power rating, but because of the overly complex circuitry required to do their power rating.

Minimalism is such a nice word which conjures up a sense of wellbeing and rightly so!

This circuit diagram is of a 50 watt amp (with a few parts missing) and it is minimalist. Transistor Q4 does all the voltage amplification on this 70 volt supply amplifier--because it can!



But when you want monster watts you need to swing more voltage and at more current to drive the output stage and its capacitance. The circuit below replaces Q1 to Q7 in the first diagram.



Twice as many transistors are needed to do the job because Q10 and Q12 are needed to swing a much higher voltage and deliver more current, but are lacking in gain, and therefore need the support of 12 other transistors. Plus it needs to be push-pull to drive the output stage.

But the output stage of the 50 watt amp isn't suitable either, we have to add transistors to get the required current gain. Just to get to 100 watts requires the output stage below.



And if you want more than 100 watts just keep paralleling up output stages like it.

The sound a monster amp makes is obviously subjective but the more diode junctions (which each device's arrow represents) adds a syrupy sweet warmth IMO which I find objectionable. Like in baking it requires more "salt" which means a load of mucking about trying to balance out its sound and eventually all reference is lost (but there are masochists I suppose).

There is a place for such amps: public address and public performance--something you only have to listen to once--and then go home and listen to something more nicely balanced.

I am in full agreement with Bruce that 10 - 100 watts has its place in the home, provided it's not "over-cooked".

I'd much rather have the more natural sound of one transistor doing my voltage amplification--devices such as a MPSA06 or BC337. They work on lower voltages and so have less voltage to swing--less of a demanding job--not as much "forced" gain.

45 volts to 80 volts of voltage amp supply (with the above devices) limits the power you'll get to between 20 and 70 watts. The sound pressure difference is 5.5dB--hardly noticeable.

So, you think you have to be a slave to your speakers? You think just because the speaker manufacturer shows off, you need to show off too with a monster amp? OK then, suffer!

These super high powered speakers have their sensitivity rated at 1 watt just like any other speaker. Hey, they'll work with 1 watt! Well, I never. Wink

Diagram Credits: Bob Cordell. Extracted from his book "Designing Audio Power Amplifiers" McGraw Hill, ISBN 978-0-07-164024-4

PS: I don't use any of these circuits. I design my own.


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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: BAK
Date Posted: 11 Jan 2016 at 2:30am
Higher efficiency speakers do play into the "minimalist" role.
   Any speaker rated above 85 dB will work for this... but the higher the better!
1st > It takes less power to get the same amount of sound... and less power consumed from the AC mains.
2nd > One can use a smaller amplifier, with headroom built in, one that is just powerful enough for your needed listening area.
3rd > A smaller power amplifier will have less active components to muddy the sound and will not generate as much heat.
       ( Graham called them diode junctions, they are in all transistors)
        Active components include valves (or tubes), transistors, and operational amplifier ICs.
4th > A smaller physical size will make for a neater sound system presentation.
         (The Proprius amps can be located behind the speakers to further reduce clutter.)


-------------
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!


Posted By: ROMPerformance
Date Posted: 11 Jan 2016 at 2:33am
Jon/Bruce, 

I hear what you're saying about the listening space, and i've already visited that idea, unfortunately my two tier office desk with two screens, 5.1 Logitech pc speakers, laptops, paperwork, printer etc..., occupies that bay window space so no go on that one hence why i have to use the 3.0Mtr wall for the large screen and speakers on stands either side. 

I'll have to get creative with a couple of portable fabric office/desk space dividers.     


-------------
Francis :0)
Majestic DAC, Proprii, Solo ULDE, Voyager, Libran, Lautus, Spatia,, Cyrus CD XT SE2, Cyrus PSX-R, Sennheiser HD 800 and 540 Ref2, Harbeth SHL5


Posted By: ROMPerformance
Date Posted: 11 Jan 2016 at 2:44am
Graham,

From what's been posted on this thread so far it doesn't sound like your little amps are going to have any problems clamped to a pair of Harbeth C7ES-3.  

I'm looking forward to the experience.

Many thanks for the circuits diagrams and explanations. 


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Francis :0)
Majestic DAC, Proprii, Solo ULDE, Voyager, Libran, Lautus, Spatia,, Cyrus CD XT SE2, Cyrus PSX-R, Sennheiser HD 800 and 540 Ref2, Harbeth SHL5


Posted By: DaveG
Date Posted: 11 Jan 2016 at 9:48am
I reckon I will have to check out a pair of Proprius (es???) before I'm too much older. My main system is evolving  into a single source. (if evolving is even the correct term for something that is actually getting simpler & simpler Wink). TT -> Reflex/EXP -> Proprius -> Speakers connected with Cusat/Spatia does have an appeal.

I used to have an some Moth series 30 stereo amps/passive pre bi-amping my Tannoys years ago. They were thoroughly enjoyable and quite capable of upsetting the neighbours. I think they were only 30 watts pc. I wish I'd kept them as a reference if nothing else. They probably went in a skip. I've also used valve amps ranging from 12 -25 watts. Volume was never an issue, though ultimate SQ perhaps was. Since then power seems to have grown & grown with each "upgrade" and I must confess my present amp is a 250w monster packed with audiovile components Embarrassed.

I'm curious. Why does a volume control perform at it's best around the half way mark Bruce? Not doubting what you say at all, just wondering what the explanation is. Indeed I've often heard this asserted before. My own amp rarely gets turned up beyond 5 past 8. The difference between loud enough & too loud is small and needs to be done by hand as the remote doesn't do small enough increments.


-------------
Dave

Michell Gorbe + HR PSU -> Cadenza Bronze -> SME V -> Elevator -> Accession -> Proprius -> B&W CM6 s2 | Cusat 50 & Spatia cables ->


Posted By: Richardl60
Date Posted: 11 Jan 2016 at 7:43pm
I am not sure whether Graham produces anything but Rothwell produce plug in attenuators that are very effective in providing greater volume range by attenuating the input signal. This my be more prevalent with Some CD players and may are likely to reduce some of the often found CD hardness. Were around £40 a pair when I last bought some some years ago.

Well made and think another good Yorkshire company!

In my experience I agree that the 'best' sound tends to come when preamp volume control is 10.30 to 12.00 o'clock best balance between openness, power, dynamics and clarity. This has been subjective on 4 amps over the years and whilst not fully sure on the science suspect may be related to minimising possible preamp overload in some cases and allowing the power amp to function properly I am sure the more educated may be able to clarify.

Richard


Richard





Posted By: DaveG
Date Posted: 11 Jan 2016 at 7:59pm
Aah, yeah - I used to have some of those attenuators - I wonder if I still do Confused


-------------
Dave

Michell Gorbe + HR PSU -> Cadenza Bronze -> SME V -> Elevator -> Accession -> Proprius -> B&W CM6 s2 | Cusat 50 & Spatia cables ->


Posted By: BAK
Date Posted: 11 Jan 2016 at 8:33pm
Make sure any and all attenuators used are completely 360 degrees shielded (encased in metal on all sides with no gaps) or you may get extra noise and a possible radio station.
#1 Any attenuator needs to be matched to the impedance of the input it is connected to at a minimum.
    It would be best to match to the impedance of the preceding stage's output, too.
BUT, matching it to the input of the following stage will be very close to the same frequency response and clarity.

NOTE: The attenuators used for Mic inputs are at a very low impedance, say 100 to 600 ohms and will not work good when connected to a 10k to 100k ohm input. Valve (tube) circuits can be as high as 1 MegOhm or more, but most valve amp inputs are 50k to 250k ohms.

Those impedance specs should be given by the unit manufacturer... many do not state the true output impedance.
 The impedance of a circuit's input and output are an AC impedance and not purely resistive.
      Any coupling capacitors and cable matching caps and coils are included with resistors in the AC impedance specs... a complicated calculation.

For those that cannot turn up the volume above "1" on a "1 to 10" volume scale, use a 20 dB attenuator.
    (For limited to "2" or "3", use a 10 dB.)
This will bring your volume control range close to the middle, "~4 to ~7" (between 10 o'clock and 2 o'clock).
    ( In scientific math, the tilde ~ symbol = approximately)

Guitar players will remember some amps having a volume scale of "1" to "11"Wink. (Making one think they had "1" more volume step above "10" .)

I had a high end 90w per chan amp in the 1980's that had a 20 dB attenuator built in. I always used it to keep my volume range close to the middle. With 97 dB @ 1w/1m sensitive speakers I couldn't turn it up above 1/10 watt before the neighbors complained.
 I can give you more info on the science of the volume control next.


-------------
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!


Posted By: Graham Slee
Date Posted: 11 Jan 2016 at 9:05pm
Originally posted by Richardl60 Richardl60 wrote:


Well made and think another good Yorkshire company!


Neh, t'badlands! (Lancashire) Wink

Originally posted by Richardl60 Richardl60 wrote:


In my experience I agree that the 'best' sound tends to come when preamp volume control is 10.30 to 12.00 o'clock best balance between openness, power, dynamics and clarity. This has been subjective on 4 amps over the years and whilst not fully sure on the science suspect may be related to minimising possible preamp overload in some cases and allowing the power amp to function properly I am sure the more educated may be able to clarify.


Another Neh. They make them do nearly full output at around 1 o'clock to sound impressive! Been there - didn't like it - resigned.




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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: Richardl60
Date Posted: 20 Feb 2016 at 1:47pm
Hi, pictures in new website great and notice the Proprius has a different power supply to the normal psu. Is it a different case or differing supply?

Richard


Posted By: Graham Slee
Date Posted: 20 Feb 2016 at 6:08pm
Yes, it's a 48 volt bought-in switched-mode with built-in short circuit protection and excellent regulation. Does 120 (real) watts.


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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: ROMPerformance
Date Posted: 21 Feb 2016 at 4:07pm
These little gems need no tweaking whatsoever.  

They are driving my 6Ohm Harbeths with ease and then some srtrapped to the back with super sticky velcro.  It's just amazing how quality sound travels at normal listening levels.  

It's fair to say everything else sounds poor to middling by comparison.


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Francis :0)
Majestic DAC, Proprii, Solo ULDE, Voyager, Libran, Lautus, Spatia,, Cyrus CD XT SE2, Cyrus PSX-R, Sennheiser HD 800 and 540 Ref2, Harbeth SHL5


Posted By: goldiver
Date Posted: 05 Jul 2022 at 11:27am
Hi all - a question for those with more technical knowledge than the likes of myself!

My Majestic-Proprius combo happily drives my Spendor standmounts in a small-medium size room, so much so that I rarely exceed 9 o'clock on the Majestic's volume dial when the Proprius pots are set to max. If I adjust down the Proprius to say 12 o'clock, the Majestic can go to 10 o'clock or beyond with comfortable listening levels. BUT the sound changes - it's more relaxed, slightly less dynamic etc.

Ohms Law tells me that turning down the volume on either one, or both, components will reduce the Power (W) output to the speakers. So why the variation in sound?


Posted By: Fatmangolf
Date Posted: 05 Jul 2022 at 5:55pm
My setting is to have the Proprius level at about 2 o'clock. It reduces the gentle hiss but most importantly means I can use the more of the Majestic volume control range as you mentioned.

-------------
Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.


Posted By: Ash
Date Posted: 05 Jul 2022 at 7:20pm
The Proprius exhibit audible hiss at high dial positions with low impedance loads like speakers. I don't set them at max or out of circuit for this reason. I set the Proprius between 9 and 12 o'clock, allowing for more usable dial range on the Majestic too. For my cardboard open baffle speakers where I listen at close proximity, I set the Proprius at 9-10 o'clock to achieve a totally silent background at the speaker cone so I can use them like enormous headphones with angled drivers. Set at an appropriate signal to noise ratio, the Proprius are just like the Solo Ultra Linear.

I guess in theory that you are better having a higher preamp level going into a less amplified amp stage; a purer output in terms of signal to noise ratio.


Posted By: Ash
Date Posted: 05 Jul 2022 at 8:01pm
Graham, could you remind me again why you don't strive to make your amp stages totally silent in terms of background noise? I always remember you saying something like "cut it too much and you've killed it". You have to juggle many parameters simultaneously and rely on 'sensible use' of the product. Basically, dead quiet amps are boring to listen to, yeah?

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We do not see things as they are. We see things as we are.


Posted By: Mikeh
Date Posted: 05 Jul 2022 at 8:45pm
I recently watched this Alan Shaw (Harbeth) video on YouTube which demonstrates how different types of music (I.e. dynamic electronic vs mellow classic) can create vastly different demand on amplifier output, for the same sound level....
https://m.youtube.com/watch?v=Y3WpRY-EtX8 - https://m.youtube.com/watch?v=Y3WpRY-EtX8

Has anyone measured the the Peak or Transient output of the Proprius? I read Bruce's (BAK) comments that into 8ohm load this could be approx. 50 to 75 W resp. It just seems that the Proprius design with it's 25 (Yorkshire ) W has plenty of capacity to handle the most onerous speaker loads and music demands, so I'd be interested to understand more.

It's an academic  question for my listening, where in a small room with nearfield positioning I can't be using 1W output for my little Harbeths to be singing.


-------------
Mike

Technics sl1210g with Victor U-2
Accession MM, Majestic + Proprius, Solo ULDE
Cambridge Audio CXC CD player
Lindemann Limetree Bridge streamer
Harbeth P3ESR XD paired with 2x REL t5x


Posted By: goldiver
Date Posted: 05 Jul 2022 at 11:19pm
I'm still wondering if there's a technical reason for the difference in sound. Is it simply that employing the Proprius pot meters, as opposed to leaving them on full, adds an extra circuit (resistors) to the mix? 

Or is the 'current' to the speakers otherwise affected?


Posted By: Ash
Date Posted: 06 Jul 2022 at 6:31am
I view the Proprius dials as being able to adjust the output impedance of the connected load. Impedance falls the further clockwise it is. Sonic differences possibly down to changes of SNR and damping factor but I don't understand it enough to say any more.

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We do not see things as they are. We see things as we are.


Posted By: Fatmangolf
Date Posted: 06 Jul 2022 at 7:54am
Yes I think what you hear is the top half of the pot resistor in series with the following bit of circuitry. They are highly Alps pots so it is normal.

-------------
Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.


Posted By: Graham Slee
Date Posted: 06 Jul 2022 at 7:56am
Originally posted by goldiver goldiver wrote:

I'm still wondering if there's a technical reason for the difference in sound. Is it simply that employing the Proprius pot meters, as opposed to leaving them on full, adds an extra circuit (resistors) to the mix? 

Or is the 'current' to the speakers otherwise affected?

Yes, there is a technical reason, but just leave it at the position it's now set at for four or five days and let me know how it sounds then.

Forgive me for not "techsplaining" too much (although I will) but such subtleties are more involved than you'd think.

There is no "extra circuit" just the pot, and although I go to every length I can to make the sound the same at every tiny increment, the "mathematics" change when a variable is introduced -- that variable being the use of a potentiometer, period.

For example, during development of the Majestic the sound changed as the volume control pot was put into different positions. It was nothing to do with the pot, or the following stage, but because of the output stage of the AD712 op-amps that had been selected at the time. Although being technically brilliant, the emitter-follower output stage, like all EF's isn't perfectly linear, and the increasing load as the volume was turned up, obviously had some effect. It was replaced by an AD823 op-amp, which has a complementary feedback pair output stage (CFP), which is more linear versus output level, and no difference in the sound was noticed.

On the Proprius, the voltage amplifier section uses a traditional feedback pair, and its input transistor "sees" any input impedance as being part of its base resistance. Due to its hFE (its current gain) that base resistance appears as part of its emitter resistance, and that subtly changes the gain of the amplifier.

So, by using the pot to change the gain setting to reduce it, it has a very subtle effect on the "fixed" gain of the amplifier as well.

Any change to the fixed gain alters the bandwidth very slightly, and in your case, has led to a noticeable difference using your speakers. All of this being perfectly normal and it hasn't changed the laws of physics (cap'n).

So, what you do, is set the variables (the pots on either item) to a position where it's just right for you.

(to understand more about amplifiers, buy my book, that I'm still writing...) Embarrassed



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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: Fatmangolf
Date Posted: 06 Jul 2022 at 7:56am
Please try the Proprius controls a bit higher up and see if that helps you.

-------------
Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.


Posted By: Graham Slee
Date Posted: 06 Jul 2022 at 8:09am
Originally posted by Mikeh Mikeh wrote:

I recently watched this Alan Shaw (Harbeth) video on YouTube which demonstrates how different types of music (I.e. dynamic electronic vs mellow classic) can create vastly different demand on amplifier output, for the same sound level....
https://m.youtube.com/watch?v=Y3WpRY-EtX8 - https://m.youtube.com/watch?v=Y3WpRY-EtX8

Has anyone measured the the Peak or Transient output of the Proprius? I read Bruce's (BAK) comments that into 8ohm load this could be approx. 50 to 75 W resp. It just seems that the Proprius design with it's 25 (Yorkshire ) W has plenty of capacity to handle the most onerous speaker loads and music demands, so I'd be interested to understand more.

It's an academic  question for my listening, where in a small room with nearfield positioning I can't be using 1W output for my little Harbeths to be singing.

If the r.m.s. voltage just prior to clipping is 14.14 volts, and the load resistance is 8 ohms, then the current is

14.14 / 8 = 1.77 amps (r.m.s.)

14.4 volts r.m.s. * 1.77 amps r.m.s. = 25.5 watts

Tell me how it can do 50 or 75 watts?



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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: Mikeh
Date Posted: 06 Jul 2022 at 8:36am
Originally posted by Graham Slee Graham Slee wrote:

Originally posted by Mikeh Mikeh wrote:

I recently watched this Alan Shaw (Harbeth) video on YouTube which demonstrates how different types of music (I.e. dynamic electronic vs mellow classic) can create vastly different demand on amplifier output, for the same sound level....
https://m.youtube.com/watch?v=Y3WpRY-EtX8 - https://m.youtube.com/watch?v=Y3WpRY-EtX8

Has anyone measured the the Peak or Transient output of the Proprius? I read Bruce's (BAK) comments that into 8ohm load this could be approx. 50 to 75 W resp. It just seems that the Proprius design with it's 25 (Yorkshire ) W has plenty of capacity to handle the most onerous speaker loads and music demands, so I'd be interested to understand more.

It's an academic  question for my listening, where in a small room with nearfield positioning I can't be using 1W output for my little Harbeths to be singing.

If the r.m.s. voltage just prior to clipping is 14.14 volts, and the load resistance is 8 ohms, then the current is

14.14 / 8 = 1.77 amps (r.m.s.)

14.4 volts r.m.s. * 1.77 amps r.m.s. = 25.5 watts

Tell me how it can do 50 or 75 watts?


Graham, having asked if anyone has measured the Peak and Transient output of the Proprius, I was simply (mis) quoting BAK's earlier estimate of Peak and Transient output...
"The Proprius amplifiers can produce 26 watts rms driving into an 8 ohm speaker load... rms = rout-mean-square (another mathematical term for average power).
 That same rms power can be as much as 52 watts peak power, or more, even 70 watts instantaneous. That is the solid state circuit doing it's best into 8 ohms.
When driving into 4 ohms it will be almost 2 X as much!"


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Mike

Technics sl1210g with Victor U-2
Accession MM, Majestic + Proprius, Solo ULDE
Cambridge Audio CXC CD player
Lindemann Limetree Bridge streamer
Harbeth P3ESR XD paired with 2x REL t5x


Posted By: Graham Slee
Date Posted: 06 Jul 2022 at 9:33am
Originally posted by Ash Ash wrote:

Graham, could you remind me again why you don't strive to make your amp stages totally silent in terms of background noise? I always remember you saying something like "cut it too much and you've killed it". You have to juggle many parameters simultaneously and rely on 'sensible use' of the product. Basically, dead quiet amps are boring to listen to, yeah?

The formula for slew-rate in V/s is

S.R. = 2π * ƒc * Vpk

(ƒc is the corner or cut frequency)

Divide answer by 1,000,000 to obtain V/us

All amplifying devices (valves, FETs, BJTs...) have parasitic capacitance which limits the extent of ƒc and therefore limits slew-rate.

Poor slew rate results in high frequency distortion, felt especially on transients.

Slew rate can be increased using brute force or by more natural means.

The brute force method always threatens stability, and so sounds artificial, but is low noise.

The natural method works with stability, and sounds natural too, but results in higher noise by comparison, due to the resistive "degeneration" required, and all resistors have a noise voltage.



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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: Graham Slee
Date Posted: 06 Jul 2022 at 10:24am
Originally posted by Mikeh Mikeh wrote:

Graham, having asked if anyone has measured the Peak and Transient output of the Proprius, I was simply (mis) quoting BAK's earlier estimate of Peak and Transient output...

I think there is a lot of confusion because of the writings in sales blurbs and due to the ignorance of the non-technical hi-fi press.

There is force, in that voltage is an electromotive force (E.M.F.).

However, current is not a force but a product of an E.M.F. across a resistance. Thus satisfying Ohm's law.

For wattage to increase, either the E.M.F. must increase, or the resistance must be lowered.

A modern speaker is a combination of capacitive reactance and inductive reluctance, with resistance thrown in.

Reactance and/or reluctance create impedance vectors, that might still be 8 ohms (or whatever the nominal impedance is), but at a different phase angle - hence me calling them vectors.

If these are parallel to the speaker resistance, then the load becomes greater than the nominal impedance, e.g.,

at the ƒc of the reactance or reluctance, the phase lags or leads by 45 degrees, and becomes 1/√2 * Rnom ≈ 0.707 * Rnom.

If it were to appear in parallel, then first 1/√2 * 8 ohms ≈ 5.6 ohms, then in parallel with 8 ohms, is 3.3 ohms.

To drive 3.3 ohms at maximum voltage (14.14) delivers 60.6 watts (14.14^2 / 3.3).

This has to come from somewhere, and that is the power supply, which for the Proprius is 120 watts.

However, circuit resistance due to the load, will drop the E.M.F., making it somewhat short of 60.6 watts.

Much of this, as you commented, is academic, in that to wholly accommodate the transients, the average or "base" "listening power" can only be the fraction demanded by those transients.

For example, if all the transients were being reproduced via the vinyl medium, then groove breakover limits them to +14dB, and within 500 to 2500 Hz.

Firstly, +14dB in power terms is 25 times the "base", so that's at 1 watt.

Secondly, between 500 and 2500 Hz, it might be less likely to encounter such a harsh amount of reactance or reluctance.

Thirdly, I doubt if in domestic listening the "base" power is remotely near 1 watt -- probably more likely nearer 1/3rd of a watt.

Now, in sound reinforcement, which is a different kettle of fish, then "difficult to drive speakers" would have consequences for the amplifier. But then, due to the non-linearity of our hearing, we would not be concentrating on the beautiful subtleties of a "holographic" stereo image. Instead, our hearing and emotions would be being overtaken by the beat. Then you need the watts!



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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: Graham Slee
Date Posted: 06 Jul 2022 at 11:16am
Something else might be responsible for the "Yorkshire Watts".

There is roughly 0.1 coulombs of charge in the output capacitor...

(hey, this guy uses output capacitors?

yes, and I'm not ashamed to admit it!)

So, although it would clip on positive excursions, the negative excursions have their own power supply sufficient to do approximately 200 amps...

But for only one half cycle at 1kHz...

Confused?

(to understand more about amplifiers, buy my book, that I'm still writing...) Embarrassed



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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: goldiver
Date Posted: 07 Jul 2022 at 10:34am
What a wonderful forum—it's a pleasure to read informed, educational responses and speculation, not to mention your Electronics 909 submissions Graham!

Leaving the Proprius pot meters on max seems to aid dynamics and energy in music reproduction, to my ear, even though there may be some hiss up close to low-impedance speakers.



Posted By: Ash
Date Posted: 07 Jul 2022 at 2:07pm
I will have to experiment further with them and see if I can hear any difference. Geek I might have to compromise on noise somewhere in the middle.

I used to use AKG K1000 (74dB/mW sensitivity and 120 Ohm nominal load) with the Proprius and could turn the dials to 3 o'clock without any hiss then used the Majestic pot at a lower level. Then I tried 12 o'clock on the Proprius and set the Majestic higher. I don't recall being able to hear any difference but headphones are spatially constricted binaurally so I will have to judge it again with two different speaker drivers, where much more spatial depth will be possible.


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We do not see things as they are. We see things as we are.



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