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Proprius Amp tweaking......

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Post Options Post Options   Thanks (0) Thanks(0)   Quote ROMPerformance Quote  Post ReplyReply Direct Link To This Post 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
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BAK Quote  Post ReplyReply Direct Link To This Post 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
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
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BAK Quote  Post ReplyReply Direct Link To This Post 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-15/625, Technics SL-1600MK2, Reflex M, Lautus, Technics SH-8066, Dynaco ST120a, Eminence Beta 8A in custom cabs;; Using Majestic DAC
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post 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, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richardl60 Quote  Post ReplyReply Direct Link To This Post 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
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BAK Quote  Post ReplyReply Direct Link To This Post 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
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 !




Edited by BAK - 11 Jan 2016 at 2:14am
Bruce
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post 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.


Edited by Graham Slee - 11 Jan 2016 at 2:04am
Not simple enough for Google-Bot to understand...
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