Truth and Tonality: can they co-exist?

[Ethan Winer]

Cheap pots don't tend to track evenly between channels ... Carbon wiper pots get noisy with age.

But you said "degrade the audio" which is different than what happens after ten years. Tubes and some speaker drivers degrade a lot worse over time. And even expensive pots can mistrack at low levels. The only solution is to use stepped attenuators or, better, digital math controlled by a single pot.

Another ridiculous audiophoole myth busted.

--Ethan

 

[mep]

But you said "degrade the audio" which is different than what happens after ten years. Tubes and some speaker drivers degrade a lot worse over time. And even expensive pots can mistrack at low levels. The only solution is to use stepped attenuators or, better, digital math controlled by a single pot.

Another ridiculous audiophoole myth busted.

--Ethan

Exactly what myth did you bust Ethan? You didn't bust anything. If even expensive pots can mistrack at low levels as you said, would that not degrade the audio signal that you hear? Of course it would. Another ridiculous Ethan myth busted.

 

[fas42]

Please remember, this is a dialectic area ...

Frank

 

[Ethan Winer]

If even expensive pots can mistrack at low levels as you said, would that not degrade the audio signal that you hear?

If the claim was that cheap pots can mistrack channel levels more than expensive pots, that would have been fine. But what was said was "I have yet to find a pot. that doesn't degrade the sound" which is clearly wrong. Nothing about stereo tracking, only some vague reference to audio quality degradation. So that is the myth that's now busted.

--Ethan

 

[fas42]

Nothing about stereo tracking, only some vague reference to audio quality degradation. So that is the myth that's now busted.

I am intrigued, Ethan. Exactly how has it been busted? I said I have heard the sound degradation effect with every potentiometer volume control I've experienced; components that used other means of volume control have been fine in this regard.

You stated "which is clearly wrong", not very scientific in my book. I am sure conventional distortion measurement techniques won't pick up anything happening, which is why I am strongly supportive of far more rigorous methods of analysing component behaviour ...

Frank

 

[JackD201]

But what was said was "I have yet to find a pot. that doesn't degrade the sound" which is clearly wrong. Nothing about stereo tracking, only some vague reference to audio quality degradation. So that is the myth that's now busted.

--Ethan

....and if you had said "Audibly degrade the sound at a specific reference voltage" you might have stood a chance of busting a myth. As it stands you have offered no proof.

 

[fas42]

there are no audible distortions in a pot....you say you hear them and offer no measurment ideaology in return, thats not getting us along in this thread with any meaningful info IMO.

My concept is that which is expressed over and over again in the literature, which is that unprotected metal to metal, or similar, contacts are intriniscally subject to corrosion or buildup of contaminants, irrespective of the quality and type of metal used. I have already mentioned the incident of an air force jet crashing, which the enquiry blamed on the gold to gold contacts in a wiring harness connector corroding. Solder provides a very effective air tight sealant for connections, I don't think you have to be fussier than that.

It's also an accepted behaviour of contaminated metal joins to exhibit diodic behaviour, that is, there is some significant level of rectification taking place with AC signals. The maker of the Lightspeed Attentuator was able to observe the non-linear behaviour of very high quality pots on a high speed storage CRO, which is where the finger on the pot reference comes from.

How the Benchmark, say, could be measured is to focus on high audio frequency behaviour, IMD with signals at very low levels, say 40, 50, 60dB down, and there has to be a time dimension to it: do the test immediately after moving the pot wiper, then 5 minutes later, half an hour later, that type of thing ...

In the end the only thing that matters is that there is some behaviour or phenomenon occurring which is repeatable: a precise explanation of why it happens is not essential for accepting that it does occur, and that therefore some means should be used for dealing with it ...

Frank

 

[Phelonious Ponk]

My concept is that which is expressed over and over again in the literature, which is that unprotected metal to metal, or similar, contacts are intriniscally subject to corrosion or buildup of contaminants, irrespective of the quality and type of metal used.

Fair enough. switches and pots build up gook (the technical term) over time. We all accept this. You're suggesting that it happens as you're sitting there listening to a song, that you can leave a pot untouched for just a few minutes and corrosion leads to audible degradation. The broad theory of what you're talking about is well-accepted. It is the specific timing suggestion, if I'm understanding you, that is not expressed over and over again in the literature. Have you done this testing? Ever seen it done? Can you yourself hear signal degradation after a pot is left unmoved for 5 minutes? And hour? Two days?

Tim

 

[Gregadd]

58 Position Volume Attenuator
The BC-1 MK-II control amplifier features an extraordinary volume control of a high reliability and smooth action that consists of 8 circuits in 58 positions - accurate to 0.2 dB at every position. All resistors are custom made to BAlabo specifications and are of superior quality with signal contacts sealed to prevent dust intrusion. In addition, copper plates are installed between each section of the volume control for shielding and absorbing acoustical vibration. The switch is mounted to the chassis of with additional isolation materials to offer complete immunity from external vibration.

But there is much more to this volume control than amazing accuracy and purity of signal transmission. A massive 4" diameter gold plated indicator dial made of a high density alloy combines with the switch mechanism to offer an unsurpassed smooth action when advancing from one position to the next. The inner black finger-hold dial is cut with precision, indexed grooves around its circumference to offer a superb, positive tactile sensation. Attenuation settings are designed with a reverse-progressive rake so that course volume increments are at the 'bottom' of the dial and finer gradations are at the 'top'. There are 25 - 1dB steps in the middle of the volume control, and 10 - .5dB steps at the top of its range. In combination with the input attenuation found on the BAlabo BP- MK-II Power amplifier, the BC-1 MK-II's volume control can be 'positioned' to operate in the user's preferred range for the most desirable volume adjustment granularity.
Somebody thinks volume controls are important!

 

[LL21]

Hi Gregadd,

Whoa! have you heard this one? i have read a great many positive comments about BAlabo. Any comments about it compares to other SOTA pres would be welcome! i have heard Krell Evo One, ARC Ref 5, CJ ACT 2, Tidal Prescenio, Shindo Masetto. Thanks! (cool picture)

 

[amirm]

Whoa! have you heard this one? i have read a great many positive comments about BAlabo. Any comments about it compares to other SOTA pres would be welcome! i have heard Krell Evo One, ARC Ref 5, CJ ACT 2, Tidal Prescenio, Shindo Masetto. Thanks! (cool picture)

I heard them with Tidal speakers at CES and thought it was top 2-3 high-fidelity experiences I had at CES. How much of that was the speaker vs the amps and electronics, I can't say. But the package was very nice sounding. The prices are way up there though: $77K for a stereo 500Watt amp.

 

[Ethan Winer]

I am intrigued, Ethan. Exactly how has it been busted?

Because I explained why it's a myth, and nobody had anything to refute me except some insults and snide remarks.

I have heard the sound degradation effect with every potentiometer volume control I've experienced

Excellent! Now show some actual THD measurements etc as proof of what you heard, and we'll finally be getting somewhere.

You stated "which is clearly wrong", not very scientific in my book.

And for scientific rebuttal you offered what exactly?

I am sure conventional distortion measurement techniques won't pick up anything happening

Ah, now we're back to the old "My ears can hear what science doesn't know how to measure."

which is why I am strongly supportive of far more rigorous methods of analysing component behaviour

Potentiometers do not introduce time-based variations, so a null test with a pot in the circuit is trival, and will reveal all distortion or other changes. Please do that and post the results here, so we can all learn how the pots you test degrade the audio. I'll wait patiently for your results.

--Ethan

 

[Gregadd]

Hi Gregadd,

Whoa! have you heard this one? i have read a great many positive comments about BAlabo. Any comments about it compares to other SOTA pres would be welcome! i have heard Krell Evo One, ARC Ref 5, CJ ACT 2, Tidal Prescenio, Shindo Masetto. Thanks! (cool picture)

AT RMAF 2010. Not enough to form an opinion.

 

[microstrip]

I can refer from direct experience a case in which there was a sonic difference due to the potentiometer.

Many years ago I owned a Krell KRC preampliifer using a Penny and Gilles potentiometer - it was connected to a high quality step motor, so the preamplifier had remote capability. It was an excellent preamplifier, I got it used form a recording engineer.

Some time later Krell introduced the KRC HR - the same preamplifier, but with a remote controlled electronically switched attenuator. I was not worried, as I did not expect any significant change in sound. However, some voices started saying the preamplifiers sounded different and I borrowed a Krell KRC HC.

I was very surprised with the difference - the new unit sounded more detailed, perhaps more etched - recordings seemed to have more information. Happily at the time it was possible to upgrade the KRC - Krell just replaced the potentiometer with the attenuator and the controller and it became an upgraded KRC HR. We checked it against the original KRC HR and it sounded exactly the same. So I can not say that potentiometers do not have a sound.

BTW, the Krell KRC or the KRC-HR had excellent measured specifications.

 

[fas42]

I was very surprised with the difference - the new unit sounded more detailed, perhaps more etched - recordings seemed to have more information. Happily at the time it was possible to upgrade the KRC - Krell just replaced the potentiometer with the attenuator and the controller and it became an upgraded KRC HR. We checked it against the original KRC HR and it sounded exactly the same. So I can not say that potentiometers do not have a sound.

BTW, the Krell KRC or the KRC-HR had excellent measured specifications.

Ta-daah! Thank you, microstrip, your experiences mirror mine virtually precisely! The only difference perhaps would be the adjectives and words used: you use "more detailed, perhaps more etched - recordings have more information"; I would use "less distortion of the treble". A typical experience when isolating each weakness in turn in system, one after the other, is that the overall sound will become more detailed, more in your face, more "accurate", more "etched" and in fact frequently this is more unpleasant to listen to. But it is a good thing, because you're getting closer to the truth! The etched quality is due to some other weakness that exists to some degree, so you have to move on and isolate that problem area, and fix it. Typically with cheap, lower quality components, just before the last deficiency is resolved the sound of the system is almost unbearable!

It is the specific timing suggestion, if I'm understanding you, that is not expressed over and over again in the literature. Have you done this testing? Ever seen it done? Can you yourself hear signal degradation after a pot is left unmoved for 5 minutes?

Yes, it is literally of the order of 5 minutes, or so. When it starts to degrade it tends to keep getting worse over a similar period and then stabilise, in my experience, so if testing is done a key issue will be the timing of that test. Once you become aware of the effect it becomes easy to pick. The friend with an analogue setup, had a reasonable HK integrated, with pot. volume of course, and after demonstrating this behaviour several times on his system he could then pick it happening. He has now replaced that unit with a Naim which uses electronic volume control. Problem solved!

The easiest test signal is music with very high frequency harmonics: shimmering crash cymbals or soaring violin solos should make it pretty obvious ...

Frank

 

[fas42]

now we're back to the old "My ears can hear what science doesn't know how to measure."

It certainly can be measured, it's just the accepted, standard techniques won't pick it up. Using an AP with the right test signals I am sure it will be observable ...

Potentiometers do not introduce time-based variations

I sorry, mine and other ears say otherwise. People agree that corrosion and contaminants are a problem, the argument just moves to how long it takes to have an audible effect ...

Frank

 

[Ethan Winer]

It certainly can be measured, it's just the accepted, standard techniques won't pick it up. Using an AP with the right test signals I am sure it will be observable

I'm sure you understand that until I see such test results - versus an anecdote saying what someone thought they heard - I remain skeptical.

I sorry, mine and other ears say otherwise.

So you're saying that a potentiometer adds a time-based variable to electricity passing through it? I'd love to hear a reasonable explanation of how that could happen at audio (not microwave) frequencies!

--Ethan

 

[fas42]

Tom, it's fair enough that Ethan asks for measurements; trouble is, I have no chance of getting anywhere near an AP, or anything like it! It will be up to someone with access to one to volunteer their services, and play around with it to get some answers ...

I don't believe anyone is going to hear this minute level of distortion given a proper functioning pot found in audiophile equipment.

If that were the case, why are BAlabo, darTZeel, Krell, and Naim going to a lot of effort improving the analogue control or changing it completely? Why can microstrip clearly hear the difference with a high quality pre-amp in two versions, one with pot and the other with electronic attenuation being the only difference?

Also please note that just because I have an heard an effect, and have found ways of getting around problems, it doesn't mean I understand perfectly what's going on! I am still trying to resolve, and work out the underlying causes in all the variables causing problems in systems, even as I write!

I am quite certain that I could show this effect to any of you reading this, on a decent quality setup with the right recording after a few go's ...

Frank

 

[Ethan Winer]

I don't believe anyone is going to hear this minute level of distortion given a proper functioning pot found in audiophile equipment.

Yes, and this is my entire point. I understand that people believe they hear all sorts of things. But that's a far cry from actually hearing something, in this case a change in distortion. Hence the need for measuring and blind tests. Maybe it's my 40+ years as a professional audio engineer, but I've understood the frailty and variability of hearing for a very long time. I don't understand why others who listen seriously don't understand this too.

--Ethan

 

[fas42]

I've understood the frailty and variability of hearing for a very long time. I don't understand why others who listen seriously don't understand this too.

Because my experiences directly contradict your experiences! Please remember, this all started for me in the early 80's, when the concept of tweaking had barely begun. And so all my discoveries were accidental, I wasn't looking for something to make a difference!

What probably helped was that my setup was extremely simple. As soon as you flood the environment with electronic gear, the cross contamination goes up dramatically. At the start I always wondered why high end audio shops sounded so hideous -- scratchy, classic electronic "hifi" sound. Then I gradually discovered that every other element in the area can have an effect, and so my journey began ...

So, it started just like it does for many scientists: I did something, and there was a subtle change, an unexpected result. And I said, "Hello, what's going on here ..."

Simple as that.

Frank