Lamm v.s Aleph

[vuki]

hi bob,

excellent series of articles about distorsion in capacitors can be found in a recent issues of Electronics World magazine. The measured results correlate very close to audibly pecieved quality of different types of caps. Interesting thing is that measured distorsions are very, very small and should not be audible?!
The best results were with film&foil caps where the foil had good connection to leads, and the worst were lytics. Another interesting thing is that two cheap nonpolar electrolytic caps connected in series showed much better results than the best polar eletrolytics (BN & silmic). Also; for many caps voltage bias significantly influences distorsion performance.

 

[Bobken]

hi bob,

excellent series of articles about distorsion in capacitors can be found in a recent issues of Electronics World magazine. The measured results correlate very close to audibly pecieved quality of different types of caps. Interesting thing is that measured distorsions are very, very small and should not be audible?!
The best results were with film&foil caps where the foil had good connection to leads, and the worst were lytics. Another interesting thing is that two cheap nonpolar electrolytic caps connected in series showed much better results than the best polar eletrolytics (BN & silmic). Also; for many caps voltage bias significantly influences distorsion performance.

Hi Vuki,
Thanks for your advice over the EW articles, which I have not yet seen as a few years ago I stopped my subscription to EW because I found there was becoming less and less each year of interest to me in that Mag.

I also have found that most electrolytics used in a signal path 'sound' or perform better if they are quite positively biased with DC, and have often temporarily connected a small battery across such a cap in circuit to see what the effect was.

Also, as you suggest, if you use two polar caps in series (+ connected to +, or - connected to -) and DC bias the junction between them, this will usually also improve the sound.

However, as you will see from my plea to Nelson, I would far rather simply avoid the entire issue by eliminating such poor sounding caps, and it seems from this post, that I am not alone in this!

I do have some test gear like a 'scope and THD meter, but being an amateur, I cannot afford any really high-end sensitive analysers etc., so for over 30 years I have come to rely on, and mostly trust my ears.

Ears may not be good at identifying several different forms of distortion which are occuring simultaneously, of course, but for my usual purposes of deciding whether a particular component 'sounds' better than another in a specific location, they are quite good when you have 'practiced' for a while, as I have.

I always try to make instantaneous direct comparisons by switching (many times) from one component to the other under test, and generally, I have found that the results are so positive and consistent, irrespective even if say I may have a head cold, am tired, or have had a drink or two, or whatever.

These conditions must be the same, though, and it is a complete waste of time relying on memory, even from only an hour or so beforehand. Too many things can change in the meantime, not the least being changes in external interference from the mains or RFI etc., or possibly even psychological influences.

It is also important to eliminate any other extraneous influences which could bias the results, for example, if one is testing a cap compared with another or even a 'straight wire' bypass, if any switches are used, similar switch contacts must be used in both 'sides' of the test (even though possibly not needed for the 'reference' side), as the switches , however innocuous seeming, will have some affect on the results.

I am a great believer in measurements, but I am still not convinced that we know precisely all of the factors involved in the 'sound' of these components, which is why in my plea to Nelson, I deliberately chose the rather vague term of the differences between "what goes in and what comes out" of a coupling cap.

You see, I have become reasonably familiar with the perceived effects of most of the well-know distortions, because I have deliberately caused many of them (temporarily) in some of my gear, to see what they actually do to the sound.

However, many times whilst testing I have noticed some artifacts (which are consistent, and not just imagination) which I simply cannot put my finger on and even describe properly.

This is very awkward from my point of view, and will no doubt provide a lot of mirth amongst the objectivists, but I have the choice of lying about it, keeping it to myself, trying to deceive my self that I have imagined it, or whatever.

The fact that I choose not to do any of these things will indicate just how strongly I feel about the matter, but I will always avoid living with these 'less pleasant' effects when they become apparent.

There is simply something about the sound which makes me feel uncomfortable, or ill at ease while listening, although with my best efforts, I still don't know why.

Whether these particular effects can be, or already have been, measured remains to be seen, and perhaps the EW article will shed some light on it.

I hope so.

Regards,

 

[Nelson Pass]

I wondered if you might comment on this thread.

My interests are primarily topological, where I have a
good opportunity to do something new and interesting.

If I thought the sound of a capacitor (for example) was a
problem in any particular circuit, I would much rather
design it out or find some way to minimize the effect.

Meanwhile, the DIY community is in an excellent position to
try out all the different parts and comment on their results.
You don't really want me spoiling your fun

 

[Bobken]

My interests are primarily topological, where I have a
good opportunity to do something new and interesting.

If I thought the sound of a capacitor (for example) was a
problem in any particular circuit, I would much rather
design it out or find some way to minimize the effect.

Meanwhile, the DIY community is in an excellent position to
try out all the different parts and comment on their results.
You don't really want me spoiling your fun

Hi Nelson,

Thanks for taking the time and trouble to comment.

Your concerns over spoiling our fun are most commendable, but to save you any sleepless nights I can assure you it would not spoil my fun, in any way, if you were to publish some more articles on the SOZ circuits, either on Pass DIY or in AudioXpress.

This would help me, for one, to do what you are so much more adept at, i.e. to build a wonderful amp, but without any awful sounding electrolytics (especially in the signal path) from spoiling the sound.

You said a while ago that they would be coming "soon", but you haven't mentioned them lately, as far as I have seen, and I notice you turned a blind eye to the plea in my last post.

Have they been shelved in favour of other revelations, or are they still on the backburner, perhaps?

I am very worried that all these requests for high powered amps etc., has turned your head.

If so, don't listen to them, this is not a democracy!!

Regards,

 

[Nelson Pass]

A Son of Zen revision is in the works. It will have
capacitors in the signal path in order to allow for
much greater circuit efficiency and independence
from the output impedance characteristic of the
source.

As you can see in the original SOZ, you pay a high price
when theology (one stage, no caps or feedback) dictates
the design.

I have other designs which do not have the dreaded
capacitor or transformer in the signal path, but
frankly, to me a capacitor is just another part; all
parts have to be considered for their good and bad
contributions.

 

[Bobken]

Hi Nelson,

Disappointing news (for me, at least) but I will still keep my chin up and believe that Lord Nelson Rules The Waves!

It was just those attributes i.e. one stage, no caps, and no feedback which so attracted me to the SOZ circuit, of course.

There is so little one can get wrong when choosing components!

Ever since you threatened us with some updates on the SOZ, I had wondered what else you could come up with for such a simple circuit without making some conceptual changes, and now I know.

Thanks for taking the trouble to put me out of my misery.

Regards from your loyal Second Lieutenant -The Victory, English Channel.