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-   -   The Audiophoolery Thread. (https://www.vintage-radio.net/forum/showthread.php?t=140332)

Craig Sawyers 25th Jan 2020 8:44 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by Radio Wrangler (Post 1211173)
A long time ago it became possible to design an amplifier to produce the required power into the requited load, with more bandwidth than anyone can hear and with trivial distortion.

The problem is that not every amplifier is designed this way. Not every one is competently designed. Rocket science isn't involved, you don't need special components stolen from a crashed flying saucer. Some amplifiers are disappointing.

It's probably less important to know exact figures than it is to know that the designer is competent and that the bean counters kept their fingers out.

As a result of the no-Zobel whoopsie, Naim was on my don't touch list. If they do such a thing and not see the downside, what else might they do? After Craig's comments, I'm warming to their later products, but I don't suppose I'm likely to ever see one at that sort of price.

David
The Naim oddities were back in the day that Julian Vereker, the NAIM founder, with self-taught electronics, was still at the helm, and hadn't passed the pearly gates, which he did in 2000 at the too-early age of 54. Since then they have moved on to exceptionally solid engineering principles.

They, like all the very few remaining UK owned companies, are surprisingly small, with a turnover of less than £30m and around 150 staff.

At least Cambridge Audio, after many decades of woe and umpteen insolvencies, is still owned in the UK, by Richer Sounds.

Craig

Craig Sawyers 25th Jan 2020 8:51 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by stevehertz (Post 1211176)
Quote:
Originally Posted by Craig Sawyers (Post 1211148)
Quote:
Originally Posted by knobtwiddler (Post 1211051)
It boggles my mind to think that a well-known OEM would market power amps that are so close to the stability threshold that some types of (admittedly audiophool) cable would take them over the edge.

The same OEM makes a power amp with an RRP of £150K. And they don't publish its THD+N spec. Publishing such mundane data is beneath them!

We ought to find someone with one of these amps and pay them a visit with some dummy loads and an AP analyser. We can publish the figure for them!
I know the guy behind these - Steve Sells. When I was CTO of Wharfedale in around 1990, we acquired Cambridge Audio, which had just gone bust (for about the 6th time in its history). They had a student who had worked for them called Steve Sells. He was clearly a real talent so I hired him. We were going to re-launch the Leak brand, and I asked Steve to design the best power amp he possibly could, cost no object. He came up with a pair of monoblocks, with comprehensive protection. They were superb, with (with our kit) immesurably low distortion and rock solid stable into any load we concocted. When I was setting them up at the Heathrow audio show, all I got was a very quiet sound a bit like an old transistor radio. I'd left the shorting plugs in the back of the speaker, and Steve's amps were playing into a short circuit - and the sound was produced by the current in the speaker cables. Turned it off with sweaty palms, took the short off - and the amps worked perfectly.

Anyhow, fast forward to his current position as chief engineer at NAIM. They let him off the leash the same way that I did at Wharfedale - and the Statement pre and power amps was the result.

Now no, they do not publish THD plus noise figures. But I absolutely guarantee that Steve has completely characterised the amps under all possible operating conditions.

If they had published them, would it make any difference to the purchase of a hundred-odd grand's piece of kit? I think not. But I again guarantee that if asked by a potential technically informed purchaser to produce the numbers, I'm sure they would do so.

Craig
Well, that only goes to show that the 'new generation' of audiophiles (audiophools?) have a total disregard (a lack of understanding?) for real life, meaningful, technical facts and figures. Personally, I wouldn't buy an amp that didn't provide a technical specification for that very reason. People who buy hifi only or mainly on the basis of subjective, fanciful, whimsical, 'audiophool' style reviews are asking for all that they get. Ironically, the complaints or negative comeback from such purchasers are often few and far between because of their slavish belief in what they are buying. It's audiophool territory, pure and simple. "This piece of kit is the way forwards, it will enhance my listening experience, it will elevate my status in and amongst audiophile groups and it will make me happy (for a while). That's the malady, that's the symptoms. The cure? there isn't one, leave the patient well alone to be happy amongst their million dollar hifi system until the next big improvement beckons.
Well that is an exceptionally cynical perspective.

Let's put it this way. If I were to win the Euromillions, I would by Steve Sell's Statement system in a heartbeat. Not for status, not for slavish belief, not for any audiophool reasons, but because I know that Steve has done an exemplary job of excellence of engineering.

Craig

Guest 25th Jan 2020 9:02 pm
Re: The Audiophoolery Thread.
 
I can still hear no fault in my little TDA whatsit stereo chip amplifier, the chip has specifications, output (20W or so) and distortion (less than 0.1%) that will do me!

Craig Sawyers 25th Jan 2020 9:11 pm
Re: The Audiophoolery Thread.
 
You can do very well with chip amplifiers. Here is one overall design that is exceptionally well specified and exemplary performance

https://neurochrome.com/products/modulus-686

Guest 25th Jan 2020 10:37 pm
Re: The Audiophoolery Thread.
 
I do like the "neutrodyne" alignment of the Zobel inductors, not that it would make any real difference. At least someone thought about it and it is a zero cost "improvement". My simple attempt only uses just one of those 15 pin jobs, the transformer cost more than the chip! The recommended Zobel for it is merrily a resistor and capacitor (10ohms 0.1uF), no inductance.

Driving a pair of Tannoy (Chinese now, awfully good) DC4s sounds great, mind you I like radio plays and the stereo image is very clear (important for a play) probably due to the small size of the 'speakers surface area and the concentric nature of them.

I would (and have) rather spend £300 on 'speakers and £30 on the amplifier/cables etc. than the other way round.

Guest 25th Jan 2020 10:45 pm
Re: The Audiophoolery Thread.
 
Oops, realised I sound like an audio pragmatist rather than a phool, apologies...

ajgriff 25th Jan 2020 10:49 pm
Re: The Audiophoolery Thread.
 
The Modulus 686 looks really good but is probably a touch too powerful for most people's needs. I do think that so called 'chipamps' or 'gainclones' combined with a decent Linkwitz-Riley crossover make an excellent basis for an active system especially for DIY builders. No audiophoolery necessary.

Alan

knobtwiddler 26th Jan 2020 2:20 pm
Re: The Audiophoolery Thread.
 
It's not often that Cambridge and Naim get mentioned in the same paragraph. One markets mains cables costing £500+ The other is owned by someone who's made it his life's work to give people bang for their buck, culminating in hiring patron-saint-of-objectivists, Douglas Self.

A problem that Naim might have, were they to publish figures for this £150K+ amp, is that they would be fighting the laws of physics to better the paper spec of the Benchmark AHB2 amp. The AHB2 (at under a fiftieth of the N's cost) can deliver full power at better THD+N than most analysers can measure. This would reduce Naim into having to justify the product exclusively in terms that cannot be quantified. But wait, they do that anyway! 'Plus ca change' as the French (owners of Naim -) might say,

Craig Sawyers 26th Jan 2020 3:16 pm
Re: The Audiophoolery Thread.
 
There are a few ways of getting vanishingly small harmonic and intermodulation distortion.

The first is to use a mixture of feedback and feedforward. There was a superb series of articles in Linear Audio on that topology and the performance you can get. It uses a lot of active devices (30+) as compared with a Self Blameless (12), and needs someone with their electronic wits about them to get it right and not build an oscillator.

The Benchmark product uses that topology, and achieves the expected exemplary performance of 3ppm over the audio band. The low weight suggests that they are using a switched mode supply, which is perfectly OK.

Another, now alas defunct one that used the same arragement was the Halcro. That went the additional step of two switched mode supplies. A power factor corrected one, feeding a second one to produce several regulated rails. That produced far less than 1ppm (Typically 0.2ppm) distortion over the audio band up to full power, and I think is the first (or only) high power amplifier to pull that stunt.

Finally there is the latest generation of class D. A good example of what is possible is the Hypex NC400 https://www.diyclassd.com/product/nc400/11 . A few ppm distortion across the audio band.

Craig

stevehertz 26th Jan 2020 3:20 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by Craig Sawyers (Post 1211183)
Quote:
Originally Posted by stevehertz (Post 1211176)
Quote:
Originally Posted by Craig Sawyers (Post 1211148)

I know the guy behind these - Steve Sells. When I was CTO of Wharfedale in around 1990, we acquired Cambridge Audio, which had just gone bust (for about the 6th time in its history). They had a student who had worked for them called Steve Sells. He was clearly a real talent so I hired him. We were going to re-launch the Leak brand, and I asked Steve to design the best power amp he possibly could, cost no object. He came up with a pair of monoblocks, with comprehensive protection. They were superb, with (with our kit) immesurably low distortion and rock solid stable into any load we concocted. When I was setting them up at the Heathrow audio show, all I got was a very quiet sound a bit like an old transistor radio. I'd left the shorting plugs in the back of the speaker, and Steve's amps were playing into a short circuit - and the sound was produced by the current in the speaker cables. Turned it off with sweaty palms, took the short off - and the amps worked perfectly.

Anyhow, fast forward to his current position as chief engineer at NAIM. They let him off the leash the same way that I did at Wharfedale - and the Statement pre and power amps was the result.

Now no, they do not publish THD plus noise figures. But I absolutely guarantee that Steve has completely characterised the amps under all possible operating conditions.

If they had published them, would it make any difference to the purchase of a hundred-odd grand's piece of kit? I think not. But I again guarantee that if asked by a potential technically informed purchaser to produce the numbers, I'm sure they would do so.

Craig
Well, that only goes to show that the 'new generation' of audiophiles (audiophools?) have a total disregard (a lack of understanding?) for real life, meaningful, technical facts and figures. Personally, I wouldn't buy an amp that didn't provide a technical specification for that very reason. People who buy hifi only or mainly on the basis of subjective, fanciful, whimsical, 'audiophool' style reviews are asking for all that they get. Ironically, the complaints or negative comeback from such purchasers are often few and far between because of their slavish belief in what they are buying. It's audiophool territory, pure and simple. "This piece of kit is the way forwards, it will enhance my listening experience, it will elevate my status in and amongst audiophile groups and it will make me happy (for a while). That's the malady, that's the symptoms. The cure? there isn't one, leave the patient well alone to be happy amongst their million dollar hifi system until the next big improvement beckons.
Well that is an exceptionally cynical perspective.

Let's put it this way. If I were to win the Euromillions, I would by Steve Sell's Statement system in a heartbeat. Not for status, not for slavish belief, not for any audiophool reasons, but because I know that Steve has done an exemplary job of excellence of engineering.

Craig
Undoubtedly, I am very cynical when it comes to the ways in which many hifi manufacturers and retailers now go about their businesses, making and selling components based on the 'new wave' of hifi ethics and beliefs; audiophoolery. Basically, it's stuff that new people drawn into hifi swallow as being true, when more often than not we're talking about totally nebulous items that capitalise on their lack of knowledge to extract money from them. So the audiophool genre grows and it gathers momentum, and we, the 'feet on the ground' objectifiers are seen as the phools - by them! That's not lost on me, though the difference is, my money is used on stuff that is 'real' using tried and tested techniques (not just hifi) whereas the audiophool is spending thousands of pounds on cables and fanciful upgrade widgets that more often than not do nothing to improve their hifi system. It's all in the mind and it's an atrocious rip off. Yes, I'm cynical!

Craig Sawyers 26th Jan 2020 3:27 pm
Re: The Audiophoolery Thread.
 
One of the trickiest things to get right with an AB amp is induction distortion. Because the power rails take half cycle currents, they can couple easily into low level circuits. That means that at low frequency the distortion is low - which is why most amp manufacturers selectively quote distortion at 1kHz. However induction distortion is frequency dependent, and leads to anomalously high distortion at upper audio frequencies.

This is not a problem with class A (because the power supply current follows the audio signal) or class D because of its operating principle.

But Halcro and Benchmark have clearly found solutions to that problem; I'd like to see inside Benchmark's case if only to look at their power supply routing!

Craig

Craig Sawyers 26th Jan 2020 3:32 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by stevehertz (Post 1211371)
Quote:
Originally Posted by Craig Sawyers (Post 1211183)
Quote:
Originally Posted by stevehertz (Post 1211176)

Well, that only goes to show that the 'new generation' of audiophiles (audiophools?) have a total disregard (a lack of understanding?) for real life, meaningful, technical facts and figures. Personally, I wouldn't buy an amp that didn't provide a technical specification for that very reason. People who buy hifi only or mainly on the basis of subjective, fanciful, whimsical, 'audiophool' style reviews are asking for all that they get. Ironically, the complaints or negative comeback from such purchasers are often few and far between because of their slavish belief in what they are buying. It's audiophool territory, pure and simple. "This piece of kit is the way forwards, it will enhance my listening experience, it will elevate my status in and amongst audiophile groups and it will make me happy (for a while). That's the malady, that's the symptoms. The cure? there isn't one, leave the patient well alone to be happy amongst their million dollar hifi system until the next big improvement beckons.
Well that is an exceptionally cynical perspective.

Let's put it this way. If I were to win the Euromillions, I would by Steve Sell's Statement system in a heartbeat. Not for status, not for slavish belief, not for any audiophool reasons, but because I know that Steve has done an exemplary job of excellence of engineering.

Craig
Undoubtedly, I am very cynical when it comes to the ways in which many hifi manufacturers and retailers now go about their businesses, making and selling components based on the 'new wave' of hifi ethics and beliefs; audiophoolery. Basically, it's stuff that new people drawn into hifi swallow as being true, when more often than not we're talking about totally nebulous items that capitalise on their lack of knowledge to extract money from them. So the audiophool genre grows and it gathers momentum, and we, the 'feet on the ground' objectifiers are seen as the phools - by them! That's not lost on me, though the difference is, my money is used on stuff that is 'real' using tried and tested techniques (not just hifi) whereas the audiophool is spending thousands of pounds on cables and fanciful upgrade widgets that more often than not do nothing to improve their hifi system. It's all in the mind and it's an atrocious rip off. Yes, I'm cynical!
Well, I hired the guy, I know him well, and he most definitely is not and never has been a snake oil merchant. He is one of the best audio engineers I have met.

You want to rubbish his achievements, well that is up to you. But I'm not going to play that game.

ajgriff 26th Jan 2020 3:34 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by stevehertz (Post 1211371)
Yes, I'm cynical!
So am I. Distortion might be measurable with sophisticated equipment but can anyone actually hear it?

Alan

stevehertz 26th Jan 2020 3:41 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by Craig Sawyers (Post 1211378)
One of the trickiest things to get right with an AB amp is induction distortion. Because the power rails take half cycle currents, they can couple easily into low level circuits. That means that at low frequency the distortion is low - which is why most amp manufacturers selectively quote distortion at 1kHz. However induction distortion is frequency dependent, and leads to anomalously high distortion at upper audio frequencies.

This is not a problem with class A (because the power supply current follows the audio signal) or class D because of its operating principle.

But Halcro and Benchmark have clearly found solutions to that problem; I'd like to see inside Benchmark's case if only to look at their power supply routing!

Craig
As an aside to that, subjectively we are able to detect distortion easier in the mid frequencies due to millions of years of us needing to decipher speech from background noise. We are 'tuned in' to mid frequencies. At both higher and lower frequencies that is not the case, and on top of that, most people are unable to hear much difference between (say) cymbal sounds and their harmonics or at the other end of the spectrum, kick drums and low bass guitar notes; they're there and they're doing their job, but people don't notice a small amount of distortion there, not so with a human voice. In recent decades cymbals have even been replaced in dance records by white noise; they're not even cymbals. Though yes, at least to me, that is noticeable!

stevehertz 26th Jan 2020 3:43 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by Craig Sawyers (Post 1211382)
Quote:
Originally Posted by stevehertz (Post 1211371)
Quote:
Originally Posted by Craig Sawyers (Post 1211183)

Well that is an exceptionally cynical perspective.

Let's put it this way. If I were to win the Euromillions, I would by Steve Sell's Statement system in a heartbeat. Not for status, not for slavish belief, not for any audiophool reasons, but because I know that Steve has done an exemplary job of excellence of engineering.

Craig
Undoubtedly, I am very cynical when it comes to the ways in which many hifi manufacturers and retailers now go about their businesses, making and selling components based on the 'new wave' of hifi ethics and beliefs; audiophoolery. Basically, it's stuff that new people drawn into hifi swallow as being true, when more often than not we're talking about totally nebulous items that capitalise on their lack of knowledge to extract money from them. So the audiophool genre grows and it gathers momentum, and we, the 'feet on the ground' objectifiers are seen as the phools - by them! That's not lost on me, though the difference is, my money is used on stuff that is 'real' using tried and tested techniques (not just hifi) whereas the audiophool is spending thousands of pounds on cables and fanciful upgrade widgets that more often than not do nothing to improve their hifi system. It's all in the mind and it's an atrocious rip off. Yes, I'm cynical!
Well, I hired the guy, I know him well, and he most definitely is not and never has been a snake oil merchant. He is one of the best audio engineers I have met.

You want to rubbish his achievements, well that is up to you. But I'm not going to play that game.
I wasn't specifically rubbishing that guy's achievements or ability, more about procedures and ways of doing business etc.

Radio Wrangler 26th Jan 2020 3:55 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by Craig Sawyers (Post 1211378)
One of the trickiest things to get right with an AB amp is induction distortion. Because the power rails take half cycle currents, they can couple easily into low level circuits. That means that at low frequency the distortion is low - which is why most amp manufacturers selectively quote distortion at 1kHz. However induction distortion is frequency dependent, and leads to anomalously high distortion at upper audio frequencies.
The main compensation pole for the feedback loop design is usually well below the upper limit of the audible range, so the open loop gain is falling beyond 1kHz, and so the beneficial effects of the feedback - lower output impedance, reduced distortion etc are scaling down with increasing frequency. This also applies to the amplifier's ability to combat unwanted signal ingress within the loop - eg output currents inducing voltages in sensitive input areas.

Inductive coupling is a two-part affair. Careful layout of the high-current source of the unwanted stuff can minimise the effective loop area and hence the field strength. Careful layout of the victim region can minimise its effective loop area or arrange net cancellation, reducing the induced voltage still further.

Like any screening/interference job, it's wise to win whatever advantage you can get wherever the opportunity arises. So don't look only at the power current loops, look also at input signal loops. They're just as important.

David

Craig Sawyers 26th Jan 2020 4:03 pm
Re: The Audiophoolery Thread.
 
Absolutely agree David. I'm just saying that it is one of the toughest things to eliminate.

I've been looking at the Benchmark specs with a more critical eye - and sure enough they only quote at 1kHz, with either a 20kHz or 80kHz bandwidth. On the main page the do say that 3ppm is met from 20Hz to 20kHz for the following table of output conditions, but don't quote the measurement bandwidth.

And in the manual, the AP plots of distortion vs output level are at an unspecified frequency and measurement bandwidth.

So even they are very carefully stepping around some of the real world issues and being economical with the numbers.

But is it a bargain for USD3000? Indeed it is. Quoting our friends from across the pond, it is a lot of bang for the buck.

Craig

Guest 26th Jan 2020 4:05 pm
Re: The Audiophoolery Thread.
 
Quote:
high power amplifier to pull that stunt.
Stunt is right, less than 1% distortion is inaudible by you average listener, 0.01% easily done. Nice bit of engineering though.

stevehertz 27th Jan 2020 6:39 pm
Re: The Audiophoolery Thread.
 
1 Attachment(s)
When did the world of hifi amplification take a major step forwards in being able to produce another octave of bass? Probably back in the 1920s?..

stevehertz 27th Jan 2020 6:45 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by merlinmaxwell (Post 1211396)
Quote:
high power amplifier to pull that stunt.
Stunt is right, less than 1% distortion is inaudible by you average listener, 0.01% easily done. Nice bit of engineering though.
But surely, it's not just a question of being able to hear 1% or even 0.01% distortion (whatever), it's the ability of an amp to exhibit clarity in complex passages? That can be affected by distortion levels that may not manifest themselves as 'pure distortion', but make for a subtle muddling of clarity.

Ted Kendall 27th Jan 2020 6:49 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by stevehertz (Post 1211733)
When did the world of hifi amplification take a major step forwards in being able to produce another octave of bass? Probably back in the 1920s?..
Quite apart from the fact that the blighter can't spell...the word is "eke".

Radio Wrangler 27th Jan 2020 6:58 pm
Re: The Audiophoolery Thread.
 
Easy to do an amplifier right down to DC = 0Hz

How many octaves down is that? well, theoretically infinity!

Realistically it depends on how long it's been turned on for and the listener's life expectancy.

Suitable speakers might be a bit of a problem.

David

Ted Kendall 27th Jan 2020 7:02 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by stevehertz (Post 1211735)
Quote:
Originally Posted by merlinmaxwell (Post 1211396)
Quote:
high power amplifier to pull that stunt.
Stunt is right, less than 1% distortion is inaudible by you average listener, 0.01% easily done. Nice bit of engineering though.
But surely, it's not just a question of being able to hear 1% or even 0.01% distortion (whatever), it's the ability of an amp to exhibit clarity in complex passages? That can be affected by distortion levels that may not manifest themselves as 'pure distortion', but make for a subtle muddling of clarity.
THD figures don't directly address intermodulation distortion, which causes most "muddying", and should be well-controlled in any respectable amplifier, but sometimes isn't. Peter Walker once said you could design an amplifier which would pass the routine tests but on which you couldn't recognise a tune. I don't know whether he ever did it to prove the point...

GrimJosef 27th Jan 2020 7:03 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by stevehertz (Post 1211735)
But surely, it's not just a question of being able to hear 1% or even 0.01% distortion (whatever), it's the ability of an amp to exhibit clarity in complex passages? That can be affected by distortion levels that may not manifest themselves as 'pure distortion', but make for a subtle muddling of clarity.
I'm not clear (no pun intended) what you're getting at here.

Distortion (if you also include noise) is, at its root, any difference between an amp's output signal and its input signal other than the obvious one resulting from the amp's gain. If the distortion is low then, well, the output signal is the input signal, only louder. I can't see how the 'clarity' can be compromised in this case.

When distortion percentage is quoted it commonly refers to harmonic distortion measured with a single-frequency sine input. Sometimes a percentage figure for intermodulation distortion, measured with two simultaneous input frequencies, is also given. It is theoretically possible for an amp to have low levels of these two types of distortion but still to misbehave when it's fed music, with its very broad range of frequencies and occasional rapid transients. But it's rare I think, isn't it ?

Cheers,

GJ

turretslug 27th Jan 2020 7:05 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by Ted Kendall (Post 1211738)
Quite apart from the fact that the blighter can't spell...the word is "eke".
As one of the fabled effects of heavy infrasonics is involuntary bowel movement, maybe they really did mean "eek"....

stevehertz 27th Jan 2020 7:06 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by Radio Wrangler (Post 1211742)
Easy to do an amplifier right down to DC = 0Hz

How many octaves down is that? well, theoretically infinity!

Realistically it depends on how long it's been turned on for and the listener's life expectancy.

Suitable speakers might be a bit of a problem.

David
Indeed, it kinda beggars belief that someone should claim that a new amp is able to reproduce another octave lower than other amps. But of course, totally in alignment with modern audiophool writings and musings. Outrageous, nothing short of.

mole42uk 28th Jan 2020 9:07 am
Re: The Audiophoolery Thread.
 
I wonder, if all the energy that has been put into this debate were used to amplify a musical signal, just how much louder would be the output?

mark_in_manc 28th Jan 2020 9:45 am
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by Radio Wrangler (Post 1211742)
Realistically it depends on how long it's been turned on for and the listener's life expectancy.

David
That made me smile - thanks! (Memories of teaching basics of FFT and windowing functions to reluctant 2nd years).

Radio Wrangler 28th Jan 2020 10:33 am
Re: The Audiophoolery Thread.
 
My favourite Fourier amusement is entirely encapsulated in the phrase "Fast bass" it always makes me smile. Trying to explain Fourier transforms and the Q of a resonance to anyone who would use that phrase might make your reluctant 2nd years look easy :-)

David

Craig Sawyers 28th Jan 2020 10:53 am
Re: The Audiophoolery Thread.
 
As applied to any half way decent electronics, "fast bass" is of course nonsense.

As applied to loudspeakers, it is much more meaningful. In particular bass reflex and ABR speakers can indeed sound bloated and muddy at the bottom end.

However, even there it is subject to analysis, as Richard Small and Neville Thiele showed in their seminal papers on low frequency speakers in the early 70's.

ajgriff 28th Jan 2020 12:53 pm
Re: The Audiophoolery Thread.
 
Although I do like learning more about some of the finer technical aspects of these things sometimes I think we should just get back to enjoying the music. Aren't we in danger of becoming audiophools if we don't?

Alan

HamishBoxer 28th Jan 2020 1:39 pm
Re: The Audiophoolery Thread.
 
Indeed Alan,you get my vote.

mark_in_manc 28th Jan 2020 5:39 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by Craig Sawyers (Post 1211879)

As applied to loudspeakers, it is much more meaningful. In particular bass reflex and ABR speakers can indeed sound bloated and muddy at the bottom end.
I think the joke we were making had to do with the time ('fast') and frequency ('bass') domains being conjoined in the form of Fourier transform pairs (in a causal universe - which in the context of this thread could add another layer to the joke!) - the window length necessary for observing anything like 'bass' being anything but fast. But as usual explaining a joke makes it less funny, and there's not much less funny than an engineering joke even when you don't explain it :)

Actually, all that stuff about 'what do you hear when you hear the Q - the freq domain band-limited gain, or the modal decay time which goes along with it' once bothered me greatly, and I even have a JAES paper or two on it. But I'm blowing my own trumpet, which is embarrassing on an electronics forum where everyone knows more than I do!

Quote:
However, even there it is subject to analysis, as Richard Small and Neville Thiele showed in their seminal papers on low frequency speakers in the early 70's.
(More trumpet blowing - I once met them both at a conference, and seizing my courage in both hands went to sit with them at a formal dinner. Alas, my leg hit the table trestle, a big (lit) candlestick tottered, and for a moment it seemed I might achieve notoriety as the man who set light to either Thiele's beard or Small's wife).

OldTechFan96 28th Jan 2020 10:06 pm
Re: The Audiophoolery Thread.
 
What does 'warm' mean when used to describe the sound produced by a valve amplifier?

I've heard it so many times. Is it just one of those things people say without really thinking?

Radio Wrangler 28th Jan 2020 11:07 pm
Re: The Audiophoolery Thread.
 
It's just the level of synesthesia that is average in the human population... For example red is associated with warm and blue with cold. Yet anything radiating blue black body radiation is an awful lot hotter than anything radiating red!

Alternatively you can interpret it as meaning that the amplifier has such a non-uniform behaviour at different frequencies that it is immediately obvious. High infidelity!

David

Craig Sawyers 28th Jan 2020 11:37 pm
Re: The Audiophoolery Thread.
 
And thus, the native hue of resolution is sicklied o'er with the pale cast of thought

bikerhifinut 28th Jan 2020 11:51 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by OldTechFan96 (Post 1212043)
What does 'warm' mean when used to describe the sound produced by a valve amplifier?

I've heard it so many times. Is it just one of those things people say without really thinking?
It means it isn't working properly.

A.

Ted Kendall 29th Jan 2020 12:34 am
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by OldTechFan96 (Post 1212043)
What does 'warm' mean when used to describe the sound produced by a valve amplifier?

I've heard it so many times. Is it just one of those things people say without really thinking?
I think it's a perception first voiced in the hi fi press during the 1970s "musicality" craze, when some writers got hold of ageing Quad IIs and the like and interpreted response errors in the pre-amps and differences in the onset of distortion compared to modern mass market amplifiers as evidence of some magical "valve" quality which they dubbed "warmth". Those who acquired Quads and Radfords, as I did under their influence, were agreeably surprised by their performance (and why not?) and only later did the realisation dawn that this was down to excellence of design and construction rather than any inherent characteristic of valves.

Conversely, in a 1966 review of the Dynaco 120, one of the first transistor amplifiers with pretensions to top-quality performance, Len Hulley spent much time between blow-ups trying, and failing with the test procedures available to him, to pin down the difference he heard between this and two high quality valve amplifiers, which he described as a subtle improvement of low level detail. This, in fact, was crossover distortion - the 120, notoriously, was pure Class B and Dynaco made a virtue of the fact that it passed no quiescent current in the output stage.

As one contributor here pithily put it - if your valve amplifier sounds warm, there's something wrong with it.

Craig Sawyers 29th Jan 2020 8:09 am
Re: The Audiophoolery Thread.
 
From the 4th Edition of the Radiotron Designer's Handbook, 1952, page 603:

"The purpose of high fidelity reproduction is to satisfy a particular listener, who is primarily interested in the emotions arising of what he hears. The complete process involves sensations and emotions which cannot be treated objectively and must bring in personal preferences and differences of opinion"

On pages 604-5 there is a section on "Imagery for describing reproduced sound"

So subjectivism and musicality it is not a phenomenon of the 1970's, it rather pre-dates Fritz Langford-Smith's RCA tome of 1952.

Craig

Ted Kendall 29th Jan 2020 8:29 am
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by Craig Sawyers (Post 1212121)
...So subjectivism and musicality it is not a phenomenon of the 1970's, it rather pre-dates Fritz Langford-Smith's RCA tome of 1952.
In general terms, of course, this is so, otherwise the hi-fi market might not have taken off at all, but the specific trend of regarding hi fi valve amplifiers as inherently "warm" dates from around the mid-seventies, at least in the UK, and was in part a reaction to the heavy promotion of ever-lower THD figures in transistor amplifiers as a "must have" parameter. Some of this may also have spilled over from rock music, where the warmth, for which read distortion, of over-driven valve instrument amplifiers is cultivated as part of the required sound.

Craig Sawyers 29th Jan 2020 9:38 am
Re: The Audiophoolery Thread.
 
Indeed - in many solid state guitar amps, there is also a valve stage which can be deliberate overdriven using a front panel control for that purpose.

But adding distortion to guitars using fuzz boxes, wha-wha pedals etc has been going on pretty much since Les Paul invented the solid bodied guitar in 1940 - and he became one of the key figures in special effects. Some of the recordings of him with his wife Mary Ford have really stood the test of time. https://en.wikipedia.org/wiki/Mary_Ford

Craig

Radio Wrangler 29th Jan 2020 9:40 am
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by Craig Sawyers (Post 1212121)
From the 4th Edition of the Radiotron Designer's Handbook, 1952, page 603:

"The purpose of high fidelity reproduction is to satisfy a particular listener, who is primarily interested in the emotions arising of what he hears. The complete process involves sensations and emotions which cannot be treated objectively and must bring in personal preferences and differences of opinion"
All fine and dandy with me.

But while they're doing this, they also make loud claims of rightess and accurate reproduction of the original sound which is somewhat amusing. But it's when pseudoscience gets wheeled out as justification for claimed perceptions that it gets silly.

People don't realise that in matters of personal taste, no justification or explanation is necessary. "I just like it" is factual and unassailable. The attempts at justification seem like signs of insecurity.

I built myself a silly amplifier many years ago. It's performance is far over the top in some respects. I built it this way for fun. It required no further justification. I enjoyed designing it. It still works and sits in the corner of my living room. It works sufficiently well that it vanishes. It is totally unimpressive. It wouldn't have made a good commercial product. It's hard to sell something imperceptible.

The Emperor didn't buy his new clothes because he liked the look of them, he bought into the lifestyle advertising :-)

David

knobtwiddler 29th Jan 2020 10:19 am
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by OldTechFan96 (Post 1212043)
What does 'warm' mean when used to describe the sound produced by a valve amplifier?

I've heard it so many times. Is it just one of those things people say without really thinking?
The concept of 'warmth' (sic) has been exploited by marketers, culminating in its ultimate conclusion, the 'marketing valve'. These have been seen in items ranging from mass-produced budget mic preamps, to car stereo head units. In order to install your marketing valve, you don't want necessary acutruments such as HT supplies or transformers getting in the way, so you might run the anode from a DC to DC converter, so you only need a couple of rails for the whole design (most of the work done with low-grade IC opamps). A dual triode, I.e. ubiquitous 12AX7, preferably from China, is also handy as you only need one for stereo. You then cut a small window in the front panel to make sure your valve can be seen. Voila! You have a 'starved plate' valve, running on 60 volts. It will sound 'warm' on account of the resultant 2nd harmonic that comes from using a valve well below its optimum B+

I can think of some items of audio that have gone onto acquire cult status with their starved plates on 60v. There's subjectivity for you!

Personally, having used valve gear designed by the likes of T de Paravincini, I reckon few would be able to discern it from well-designed transistor circuitry in an ABX comparison. Mr P's designs get criticised in hifi circles for being too clean! He does his job too well.

Sinewave 31st Jan 2020 8:52 pm
Re: The Audiophoolery Thread.
 
Quote:
Originally Posted by OldTechFan96 (Post 1212043)
What does 'warm' mean when used to describe the sound produced by a valve amplifier?

I've heard it so many times. Is it just one of those things people say without really thinking?
Certainly with guitar amplifiers, a valve amp has a fuller warmer tone. Solid state amplifiers tend to have a thinner sound, can often sound compressed. It makes a big difference.

I refer to it as warmth and depth.

stevehertz 31st Jan 2020 10:52 pm
Re: The Audiophoolery Thread.
 
Out of interest, the use of the word 'warm' to describe the sound of a valve amp, tuner, whatever, is also frequently used to describe the sound of any vintage hifi be it SS or valve. It's also a popular 'big up' often used to aid a sales pitch. My own explanation of how the term came about is more to do with what the hifi component isn't, rather than what it is. And by that I mean 'less treble'. Not that I think it's use in that context is justified, but nonetheless it's used that way.

M0FYA Andy 26th Feb 2020 4:13 pm
Re: The Audiophoolery Thread.
 
Here's a new one on me, concerning valve rectifiers in a guitar amplifier affecting the guitar's strings -
"As more power is consumed (you turning the amp up!) an increased voltage drop occurs, resulting in the time-honored tube-rectified feel. The overall response is ‘spongier’ and causes the strings of your guitar to feel more elastic and often easier and ‘more juicy’ to play".

Andy

fetteler 27th Feb 2020 2:14 am
Re: The Audiophoolery Thread.
 
Are you a guitarist Andy?
It doesn't affect the strings per se, rather I guess they mean it affects the feel of how you play, we are all used to hitting the strings with a certain force for a desired sound and the amp, being in 'series' with this chain of sound will thus affect the feel of the guitar. pretty obvious to me.
Steve.

Ted Kendall 27th Feb 2020 8:05 am
Re: The Audiophoolery Thread.
 
Agreed. Anything which changes the apparent response to manual control inputs (onset of overload in this case) will affect the "feel" of the whole, rather like a stiff accelerator pedal in a car.

Craig Sawyers 27th Feb 2020 9:46 am
Re: The Audiophoolery Thread.
 
Another odd positive side effect of valve rectifiers is the lack of reverse recovery. They therefore do not excite the leakage inductance/interwinding capacitance resonance of the mains transformer.

Regular solid state rectifiers generate reverse recovery transients like a champ, so every time each rectifier diode turns off, a burst of oscillation occurs via the above effect usually in the range 200kHz to 1MHz with a Q of 5-10.

Of course you can use more sophisticated soft recovery diodes, and/or use a C-RC snubber across the secondary winding of the transformer, which kills the oscillatory transient dead if you get the RC in particular correct.

There is a small circuit on DIY audio that enables these values to be determined by direct measurement https://www.diyaudio.com/forums/powe...-test-jig.html

Craig

avocollector 17th Mar 2020 5:36 pm
Re: The Audiophoolery Thread.
 
I've always thought of 'warm' as bassy ie sound has a lot of bass content and not very high trebles, I understand that valves emphasise the even harmonics and trannys the odd which may also have something to do with the sound - after all the early tranny radios and amps were often said to be 'tinny' = emphasising the trebles.

But there again this may all be due to what our ears get used to as a child - I was one back in the 50-early 60's so valve amps were the norm back then, I don't notice it so much nowadays but a) speakers have got a lot better b) my hearing is probably starting to go a little at the top end as a result of being 67.


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