Today I placed up a thread, asking if anyone has heard a Graham Slee Headphone Amp.

So far this is the response...

https://www.audiosciencereview.com/forum/index.php?threads/graham-slee-headphone-amps.14525/#post-447722 - https://www.audiosciencereview.com/forum/index.php?threads/graham-slee-headphone-amps.14525/#post-447722

As a youtube audiophile says on his videos, the only person that needs to like the sound of your hifi is you.

That is not a responsible response... the person did not even listen to the unit.

They only read the "not-inflated" specifications.

Every Graham Slee product is tested on an Audio Precision analyzer to meet or exceed the design specifications stated for that product.

It seems the general consensus is that if a gear doesn't measure "well" it cannot sound "good". 

Very often this conclusion is derived without proper listening tests, and this is where things tend to go pear-shaped over there.

Agree with you. Welcome to the internet.

To me I like the plug it in and play some music with great sound quality and THATS what I get with Graham Slee. I have a CD player with a load of digital filters and things and I only use the default setting, could not hear any difference with the other filters settings

KEEP IT SIMPLE THAT'S WHAT I SAY

Agreed.

S.

That spec-quoter hasn't even heard one...

Spec's mean nothing! If it sounds cr-p. If you are going Digital then yes I think you have to (don't know much about that side of thinks) as I only have a CD player.

Listen with your ears not the spec's   THATS what say

Agreed. Listening is believing as I wrote on the forum some years ago.

I say this because these things are virtually free, and I see people who roll new gear in and out of their rooms. 

I'll also say that the cable debates are THE MOST TEDIOUS dead horse in audio, but I do tend to look to other industries—like medical and defense. If these industries are paying up for technology, then one can certainly argue that they don't apply to audio because nobody can hear the differences, but trying to argue that these technologies are snake oil and that the medical and defense industries are being defrauded really takes the cake.

I bet my system would sound really off if I removed all my Lautus interconnects and replaced them with cheap alternatives or those of silver construction. It would be like changing the PCB layouts of the circuit boards if you introduce antenna-long cables with no shielding at all. The characteristics of a cable would have to be drastically unsuitable for me to hear a difference though I think. Asking me to differentiate between a Lautus and CuSat50 interconnect in a blind test would likely be inconclusive, seeing as they are almost of equal construction.

Now...I have heard differences. Subtle differences that even one as loquacious as I would have extreme difficulty describing or quantifying. But not placebo. I think. 

And there I shall leave it for now, because cable debates are so outré...

Hi Mark!

From a GB perspective, I can only add that our "defence" industry is regularly defrauded (and worse) by suppliers such as BAe, Siemens et al - see Private Eye passim, ad nauseam.... 

f.

With cable comparisons, I would just say: "Yeah, the sound has improved purity and resolution when I use this cable in place of the other one" or "I can't hear any difference in the sound through either". The comprehensive story-telling reviews tend to piss me off because they rarely give the reader anything conclusive or truthful, sometimes leaving them more confused or with more questions. Maybe it's just me but there are very few audio "professionals" that I trust online. I can count them on one hand and struggle to count them on two.

I like Ash's approach, keep it simple and to the point. I can usually tell quite quickly whether I prefer the new item to what I have already, generally more clarity/separation and a natural sound is my preference. If there is an improvement a lot of listening follows with the temptation to describe it at length and justify the expense. Of course it is cheaper if the test outcome is the other way round!

Also, every industry in the world uses inflated marketing copy to present their product in the best light. I am thoroughly confused at why one tiny industry would eschew this trend and only present their products without hyperbole. 

Why: large profits!

Use the bits you find make listening enjoyable. Leave everyone else alone to do the same. Job done.

Music is absolutely objective, but our perception is not. My two best friends have become investors in hifi because of their experiences in my listening room. Great! But listening to their seriously researched and auditioned systems, it’s very clear they value a different experience than I do. I reckon that’s how it should be. 

Cheers,

Mick.

 

jupiterboy wrote: I'd really like to hear a discussion wander into the applications of conductive and semi-conductive dielectric materials. The whole idea of addressing EM field outside the cable—that never, ever gets any reasonable light.

I once tried to do that, but the Advertising Standards Agency (UK) told me I was in breach of their rules, and I had to take it down. They told me that they'd had a complaint by a college lecturer (no other information supplied), and that was good enough for them to find against me.

Freedom of speech?

Better yet, make the Lautus interconnects a "forum members only and private message request" purchase and say nowt.

If you're not "advertising" a specific product for financial gain, they have no grounds to make a claim against you and seeing as there are plenty of genuinely "sh*te" products out on the market being sold, such as cable pylons et al, they would be utter hypocrites to do so.

Ash wrote: ...plenty of genuinely "sh*te" products out on the market being sold, such as cable pylons et al, they would be utter hypocrites to do so.

It would seem that the college lecturer hasn't complained about those products

F*** the aristocracy.

Amen to all that! 

jupiterboy wrote: I'd really like to hear a discussion wander into the applications of conductive and semi-conductive dielectric materials. The whole idea of addressing EM field outside the cable—that never, ever gets any reasonable light.

I'd learned a bit about radio frequencies studying for my 2m radio amateur license exam with the RSGB (early 1980's). However, other things got in the way, and I never sat the exam. My interest in radio communications fell away, as I had to concentrate harder on earning a living.

My next brush with radio frequencies was at the beginning of the EMC regulations, starting about 1995. I had already spent four years in broadcast, but working on audio, not the RF end. However, I knew about over modulation, and the audio circuitry had to meet tests regarding retransmission. So I had an understanding of EMC already.

I attended EMC seminars and was given the responsibility of keeping abreast of EMC in a freelance position in 1997.

The products I design have also to comply with EMC legislation, and they do. Although I have never been able to demonstrate it by third party laboratory testing (except for the PSU1), I have used the same self-declaration approach of most in the audio industry.

Our full range of products was EMC tested in South Korea, by a distributor who was required by law to do so. Every product passed.

When designing the Accession, I wanted to ensure its EMC credentials were squeaky clean and having read about Cherry Clough Consultants, and their work for the Advertising Standards Authority, I thought I could not go wrong in hiring them (quite expensive).

I was also developing the Lautus interconnects, and under the same consultancy costs, these were discussed.

Cherry Clough had reported on the false advertising as an expert witness, of another hi-fi firm for the ASA. After being hauled over the coals by the ASA for my explanations about the Lautus USB cable design, I explained that I was using their chosen consultant, but that made no impression on them. They'd had a complaint from a college lecturer, which topped my use of one of the most well-known names in EMC.

I am willing to discuss the thought process involved in anti-nodes, which isn't a secret by the way, and the way a half-turn ferrite core works on RF attenuation. Or I can guide you to resources about it. Just let me know.

What did you say that the Lautus did that was objectionable?

According to BS EN 61000-5-2 we need parallel earth conductors for all signal cables. We need to fit segregated trunking to our racks to get signal, ac power, and dc power cables separate then bond the equipment chassis’ to the trunking with earth straps or braids (not round cables as they don’t have sufficient surface area.

The trunking (galvanised steel) forms the parallel conductor for us and having a high surface area provides a low impedance bond at high frequency. All equipment will be on the same equipotential ground plane, audio nivarra surely. Yes I am joking.

Chris,

Firstly, the Accession C has a solid ground plane, but after supplementing it with 7/0.2 equipment wire between input ground and the 0V connections local to each op-amp, the noise and distortion measurements improved. Allegedly, and according to every EMC engineer who has published anything about ground planes, what I have said is not possible.

PS, dare I say it? It sounded better too!

I think:

Anti-node = region of peak amplitude

Node= region of zero displacement

It will be the anti-nodes, my notes from October 2012 have:

velocity factor, VF = speed of light in dielectric / speed of light in vacuum = 1/sqrt(e) where e is the dielectric constant

Reception is zero at beginning of cable so quarter wavelength (antinode) out from shielded source is the key position, that is the first peak in the wavelength or lamda /4

For 100 MHz in vaccuum would get 75cm for lambda = 3m, adjust for the VF of PE cable and you get 50cm for antinode/ferrite position (using PE which has VF 66%) - put the ferrite bead there

Halve this for 200MHz, it has half the wavelength so 25cm. This would be at lambda/8 of 100MHz so one bead at 25cm and one bead at 75cm (i.e. 50cm further on from the first one)

Foamed PE has VF 82% so increase the spacing in proportion. Nylon and PVC (in some mains cables) is around 50% so closer than solid PE.

Graham was right and it worked! The theory made sense to me back then and still does. Science and good engineering put a ferrite in the right place on an audio or SPDIF cable for known radio interference, better than randomly chucking a ferrite on a cable as seen elsewhere which makes no sense if your aim is to protect an unbalanced signal by stopping a RF signal imposing itself on the ground/return so it appears on the signal too and overloads the input of the next piece of equipment.

Hope that helps Ash and my acknowledgement to Graham for repeating what he worked out and shared.

100MHz region of the radio band is chosen as likely has the best potential for attenuation as it is the typical frequency area used in FM radio transmission so contains the most radio interference to suppress.

If you wish for signal attenuation at an alternative frequency region, the ferrite position is moved to reflect this. The cable has to be connected the "correct" way around (marked arrows on sheath) for the signal attenuation to be in the "culprit" region chosen. It is not a "palindromic" distance.

Why a 200MHz calculation? For the second harmonic of the fundamental wave?? If you had a 10m cable and the signal amplitude were not significantly attenuated by that length, you could have a series of ferrites along the cable that gradually get closer together by a factor of VF%, as long as they fit on the cable?

The physical contact that the sheath/insulation makes with the EM shield is also important. I assume that is why users were encouraged to gently and carefully bend the cable slightly along different parts of its length to ensure that the sheath is as separated from the shield as possible. If not, could the filter be bypassed to some extent? I understand that I may be asking too many questions...

One more thing, is velocity factor a similar principle to refractive index? A constant between 0 and 1 that considers the speed of light in the medium compared to the speed of light in free space (vacuum).

It worked.

As for the rest of your questions, I'll let Jon answer them

I kind of understand yet am very confused at the same time.

We are so used to visualising currents as direct current rather than alternating current. The energy propagates through the conductor very differently.

Ash wrote: So by the logic of "it worked", each ferrite point must act like the start of a new cable?

That was one way I looked at it.

Thanks Graham. I used your formula to position ferrites on some mains cables. It was not always discernible but seemed to sharpen the picture on the TV.

jupiterboy wrote: Honestly, my room imposes such dreadful nodes and antinodes on the bass that I'd have a hard time telling if I had the ferrite core right. lol

That's why we go through the pain for you

Room ratios, BBC acoustical engineering guide, rebuilds, laser cut absorbers, lots of wasted effort and materials (an abandoned new building!), and eventually we arrived at the equivalent of a control room regarding how it sounds... or we can use headphones!

So Graham, if the ferrite position is essentially the end of one circuit and the beginning of another, would it not be wiser to place the next ferrite at the same distance again, to attenuate the fundamental frequency rather than its second harmonic?? The amplitude of the fundamental is also higher than that of subsequent harmonics so more to attenuate?

With all the expense of setting up speakers for optimum performance and reference sound, perhaps £3.5k MySphere is a more sensible choice? An expensive investment but backed up with plenty of R+D and extensive sound measurement techniques.

But all this is theory anyway, although I would like to be able to measure it one day.

That said, interesting stuff although much of it goes over my head...

Like the science and logic goes over the heads of those at Audio Science Review. 

S.

https://www.audiosciencereview.com/forum/index.php?threads/graham-slee-reflex-c-review-phono-stage.19247/ - https://www.audiosciencereview.com/forum/index.php?threads/graham-slee-reflex-c-review-phono-stage.19247/

Not a forum I look at often, as they are purely measurement based.

In their reviews, they never listen to it.

With my HiFi, I do the opposite.

I agree.

do any of them listen to the product on that forum, It MAKES me wonder if they listen to music.

IT'S the sound and build quality that matters to me not how it looks. they could not agree on the price of it. 

1. If it measures good it must sound good

2. If I can’t personally afford it it must be crap value

3. “Ha, got you! Your thing measures crap and you’re a sucker.”

Did I get it all? I follow a number of designers in their commentary and design ethos, and none would agree with any of those statements above. It’s a very small community on that site. It seems populated with people just wanting to justify their own purchases and be mean to those who don’t agree.

It’s the worst kind of pathetically weak standing behind “I’m entitled to free speech”, anti-thought, anti-democracy intellectually lazy charlatanism.

Can we just ignore them? We’ll be happier.

Mick.

Fact is, records are a noisy format. There is always going to be noise, whether from the cartridge or the record itself. We like records anyway for reasons that are rational and not so rational. 

The main beef there seems to be mains noise which was detected under his measurement. I don't know what happened there. Amir does mention that audibility of that mains noise would be low. Probably not something one would hear when playing an actual record. 

As for overload, I don't think it's a problem with the Reflex C either, but people are likely to misinterpret the info given. To my understanding, we should be looking at the max output of the unit, which in this case is 4.9 Volts. 

Here are some quick Excel calculations. Note that this unit tested must be an older unit, because the gain measured was 59.2dB, not 62dB as with the current iteration of the Reflex C. 

If my calculations are correct, that's 20dB of headroom for actual records with a 0.5mV LOMC cart. Even if you own a bunch of hotly cut records like I do, none of them are going to be cut at +20dB. Likely +12 to +14dB for hot records. 

His max input test is used as a proxy for how annoying clicks and pops are going to be with a given phono stage. I'm not sure if that's a good idea. A better idea would be to record actual clicks and pops digitally and run them through the unit and then measure. Or at least simulate those clicks and pops somehow with specific types of test tones. I'm not sure any industry standard test for this parameter (clicks and pops) exists, or at least, I haven't seen one. 

He does mention that the dynamic range is good, the RIAA EQ is accurate, and that the clipping is at the same level for all frequencies. 

Never does he listen to it in a system, which is what HiFi is all about.

How does the device influence the music? Does the sound please me?

I agree with you.

You say he never listen to it in a system then how can he say weather it's going to sound good or not. To me measurements like these are like stats you can make what ever you like out of them, Read into them how YOU like, Some one else reads them differently. Like football the stats may say your team had all the possession so on paper they won but the result is your team lost. ( that's the best way I can put it)

I hope you get what I mean!!!

The person that posted the Google Street View comment is a new member with only one post to their name over there. 

I guess they didn't see the irony that ASR also measures equipment out of their house and that the proprietor (a retired software engineer IIRC) also runs a home theater installation company out of his house, with another space in a shopping center. Based in Bellevue, WA, USA. 

https://www.madronadigital.com/team-amirm - https://www.madronadigital.com/team-amirm

Here's my layman's arithmetic. 

59.2db = a gain factor of 912

The correct gain factor should be 1260

912 divided by 1260 = 72.38%

Oh, and by the way, I didn't know that was one of his measurements/complaints before I wrote

https://www.hifisystemcomponents.com/forum/the-audio-science-review-forum_topic4993_post66229.html#66229 - https://www.hifisystemcomponents.com/forum/the-audio-science-review-forum_topic4993_post66229.html#66229

I never visited his website and I don't recall you telling me about this.

Right, this confused me at first but now that you have explained the output from the analyzer was wrong I understand, or at least well enough for a layman. 

His frequency response test (inverse RIAA test tones?) shows a "hump" of 0.5dB from around 30Hz to 50Hz, which gradually tapers off before showing a very accurate RIAA curve response. Amir calls that a "bass boost" and concludes it is due to a high pass rumble filter. 

Having read your previous posts on not liking rumble filters this obviously has me confused. 

Re: Amir's complaints, it seems his main complaints were the overload margin, which he assumes is too small and will exaggerate clicks and pops, and the mains noise and general distortion. I will conclude that the latter is due to the wrong input on his analyzer as you explained above. 

He doesn't like vinyl AFAIK and does not even own a turntable AFAIK. His forte is mainly digital audio, again, AFAIK. 

Given that he made a measurement error, if it were my site (which it is not), I would take down any phono preamp review that's been done to date until things can be remeasured properly.

Leaving up bad info does no one any favors. I doubt this will happen though. 

IMHO, the site grew too quickly and he ended up with piles of equipment to measure. Rushing through it all, combined with his lack of familiarity with measuring phono preamps, means you end up with mistakes. 

That's my 2 cents on the situation. 

And yeah the peanut gallery there needs much better moderation. 

From my own tinkering and taking lots of things apart I learned that not needing all the parts to put it back together doesn't make you cleverer than the manufacturer. A little knowledge can be a dangerous thing and I have certainly had that 'doh!' moment quite a few times.

I figured he was dead wrong about the rumble filter. Thanks for explaining all this. 

Having borrowed the loaner propriuses and been impressed I wanted to listen to a modern class D amplifier to see what one sounded like before I parted with what for me is a sizeable sum.

I managed to borrow a power amp that impressed the folk on ASR for a couple of weeks.  To be fair to it, in stereo power amp form it cost significantly less than a pair of Propriuses.  Plus points were a very low noise floor, excellent dynamic range and good control of the bass.  Negative points were a thin and wirey treble and mid range and flat, almost 2d imaging on all the sets of speakers I tried it with.  

.

.

Worse still from the same sources it presented a fraction of the detail presented with such clarity by the propriuses.  In that respect it was also trumped by a twenty year old marantz amp I bought on eBay to tide me over when my last decent amp died.

Clearly there seems more to measuring the performance of an amplifier than applying some test tones and some measuring equipment to it.

I know I have middle aged ears which may be not as good as they were and are possibly used to listening to inaccurate amplifiers but they listen to live music which sounds much more like what I hear from the marantz and the propriuses than the beautifully measuring class D amp.

https://darko.audio/2021/04/podcast-jonathan-novick-audio-precision-aes-cta-on-measuring-audio-gear/ - https://darko.audio/2021/04/podcast-jonathan-novick-audio-precision-aes-cta-on-measuring-audio-gear/

Cheers,

Mick

It's not every day you see the same AP we use

(image courtesy Mr Darko's website)

Now getting on for £15,000 (plus VAT), it cannot tell you how the D.U.T. is going to sound!

By the way, neither can it tell you anything without having a rather powerful PC connected to it, running AP's software.

Interesting video.

Audio Precision's James Kelly (ex head of testing at IAG) demoing the audio analyser options to us in our test department around seven years ago.

Already on our test shelf is an ATS-1A, and James is demonstrating the AP-2700 against the APX525, by measuring our Majestic pre-DAC in both analogue and digital domains.

The ATS-1A now serves as the 100% production analyser in John's workshop, while the APX525 serves as R&D analyser in my workshop, and is sometimes called on to put Majestics and Bitzies through their paces.

John and I have been using audio analysers since 1989 when Neutrik Liechtenstein made a 'big' analogue analyser. We also used Lindos and WK analysers at YRN. The WK (https://www.waynekerrtest.com/history.php) retired to my workshop in the late 90s and was used in 100% testing of my first products, 1999 to 2006, when the ATS-1A took over testing duties. Whereas the ATS-1A requires recalibration, the APX525 is self calibrating through software.

Along with Audionics' Phil Davies, we've tested a good proportion of the UK's commercial radio stations, BBC analogue desks, as well as projects for Independent Television companies.

I await to hear of the Audio Science Review Forum's equivalent experience.

May as well watch the video here:

See my 1970s Design Indulgence topic!

and

So true,

 But Graham's measurements are honest representations of a device's performance.

AND, he does a sound quality test by playing real music to make sure a unit sounds good.