Which Capacitors for Audio?

[Walter66]

The main justification for promoting high damping factor is loudspeaker control, so it's been taken seriously since the early 50's.

The very early speaker designs often had much better control of speaker- amp interaction. It's often said that transistor amps have a great advantage in this field, but the best controlled speakers I've auditioned were early types, means pre 1950's production.

It has been taken seriously since the early beginning of the design of speakers and man, those engineers knew what they had to do to let it sound right.

Today, with the small enclosures and tiny speaker chassis which should deliver deep bass in small enclosures, we often don't see good speaker control, even with transistor amps. The speakers have to move a long way to reproduce low frequency with significant level. When such a speakers chassis is still travelling to its maximum deflection, the 15 incher is already finished moving and patiently waits for the next music impulse.

That's my comment to "new is always improved and therefore better".

 

[Ricardus]

Absolutely. Double blind is useless, inefficient and unproductive. The last thing you want is for your listeners to be completely at sea. It makes them nervous, uncomfortable and self-conscious. It's a shibboleth, and is only used, if ever, by people who worship at the altar of scientism. Do you blindfold yourself at Hi Fi shows or in shops? I thought not.

Ah, so you believe in magic.

You might not like double blind because science is real, but it's the only way.

Subjective listening tests are nonsense.

 

[Ricardus]

I feel like what we have here is another of the audiophoolery fake accounts like we've seen before. Here to waste our time.

 

[abbey road d enfer]

This is a really good thread. I sure hope it doesn’t spiral out of control. I like having members from the hifi world contributing.

Me too, but when they have a tool missing from their toolbox it's not so great.

 

[Gold]

Me too, but when they have a tool missing from their toolbox it's not so great.

I just would like it to stay about capacitors. Technical disagreements about capacitors are welcome and interesting.

 

[abbey road d enfer]

Can you expand on what you mean here wrt Apple ? Interested in the hearing impairment implications. Thanks in advance.

Harman, not Apple, sorry. Check the numerous links to "Harman curve".
Apple is only guilty of following in their footsteps.
See my post #158 there Headphones for Mixing and Mastering
Regarding hearing loss Headphones & Hearing Loss and many others

 

[abbey road d enfer]

I just would like it to stay about capacitors. Technical disagreements about capacitors are welcome and interesting.

Agreed, but unfortunately the subject seems to attract believers and snake oil addicts.

 

[Audio1Man]

Beauty is in the ears of the listener.

Listening to the product is only one of the tools needed to evaluate the product.

I worked for a guitar amplifier company for many years (mid 1960). After several great projects, I was asked to develop a “VERY CLEAN STUDIO GUITAR AMPLIFIER”. The during the firsts listing tests it was Not Well Liked. THD% & IMD% were very low, damping factor was high (no speaker ringing).

All of my previous product I used to listen to the “ERROR OUTPUTS” of the Distortion Analyzer. Using a sinewave signal adjusting frequency and levels and adjust circuit value’s for even, odd and unbalanced harmonics, the products were born.

My next job was for a large audio power amplifier company and I still used the “ERROR OUTPUTS” skills in the development process.

After using my skills developing audio test equipment I still listen with my ears.
Duke

 

[abbey road d enfer]

The very early speaker designs often had much better control of speaker- amp interaction.

The main reason was loudspeakers were designed for efficiency. If bass was needed, a large speaker was used.
The use of an "underhung" voice-coil, where all the voice-coil is in the magnet's magnetic field results in permanent motional control of the voice-coil movement, but also limited excursion.
Modern speakers use "overhung" voice-coils, which results in only a fraction of the voice-coil being under motional control. This provides better linearity at large excursions, at the cost of impairing low-level efficiency.
The actual control the amp has on the speaker, as suggested by damping factor, is almost irrelevant since the output impedance of amps have usually been much smaller than the DC resistance of the voice-coil. Some designers have conducted tests with varying degrees of damping, from no damping (current-drive) to negative-impedance, as JR reminded.
In particular, current drive has its followers, but implies the use of specifically designed transducers; it works well for midrange, not so well for bass.

 

[Gold]

Beauty is in the ears of the listener.
After using my skills developing audio test equipment I still listen with my ears.
Duke

I’d rather have you listening than 100 walk in’s.

 

[abbey road d enfer]

Beauty is in the ears of the listener.

Listening to the product is only one of the tools needed to evaluate the product.

I worked for a guitar amplifier company for many years (mid 1960). After several great projects, I was asked to develop a “VERY CLEAN STUDIO GUITAR AMPLIFIER”. The during the firsts listing tests it was Not Well Liked. THD% & IMD% were very low, damping factor was high (no speaker ringing).

The iconic "Fender clean sound" is about 10% distortion and a big speaker resonance hump.
It can't be ignored by anyone who wants to design a guitar amp.
Gibson found out the hard way with their Lab Series.

 

[abbey road d enfer]

This is a really good thread. I sure hope it doesn’t spiral out of control. I like having members from the hifi world contributing.

You may note that this thread was particularly well-behaved until post #141...

 

[Nick Nack]

I don't know about a "dislike" button, but maybe a "calm down" button?

This thread has been most excellent. Not many forums where you can get as far as post #141on a subject like "capacitor sound" without Godwins Law showing effects.

Mind, one sure way to return to ForumNormal is to introduce, in the absence of a "flouncing off in a huff" button, vaccine scepticism. Or Brexit (my other favourite).

 

[thor.zmt]

The crux is the E in ESR. E for "Equivalent".
ESR is a moving target. It is usually spec'd at one frequency, but actually it's a virtual value resulting from several individual factors, some being perfectly stable and constant, others being variable.

Yup.

The best way for minimizing the effects of this variability is making sure it is small in comparison with the load, which again results in choosing the value of an electrolytic coupling cap much higher than the old rules of thumb would suggest.

Well, or making it constant by using non-chemical capacitors in all positions that do not loop negative feedback around the capacitor and limit electrochemical capacitors to positions where they are inside negative feedback loops, in which case they are part of the output stage non linearity.

In fact, I would suggest both using FET Input Amp's with lowish value series capacitor in film and suitable bias resistor and wrapping negative feedback around polarised electrochemical capacitors WITHOUT making them ridiculously large is by far better and most of all smarter.

Thor

 

[abbey road d enfer]

Mind, one sure way to return to ForumNormal is to introduce, in the absence of a "flouncing off in a huff" button, vaccine scepticism. Or Brexit (my other favourite).

These subjects are strictly constrained to the Brewery.

 

[abbey road d enfer]

In fact, I would suggest both using FET Input Amp's with low series capacitor in film

There are cases where it's not possible. For example the parametric EQ section in a mixer. High-value pots are not desirable for noise reasons. Using servos, not only at the ins and outs, but at the potentiometer nodes is unconceivable. The only practical solution is to use electrolytic caps. Until only recently FET input opamps were too noisy for this application.

 

[MicUlli]

There are cases where it's not possible. For example the parametric EQ section in a mixer. High-value pots are not desirable for noise reasons. Using servos, not only at the ins and outs, but at the potentiometer nodes is unconceivable. The only practical solution is to use electrolytic caps. Until only recently FET input opamps were too noisy for this application.

In 2023 i would suggest that EQing and mixing is done in software...
Cap sound differences and myths about it are a never ending story. IMHO caps have to be selected use case dependent. 4,7 uF in a speaker crossover circuit is not the same as 4,7 uF in a preamp for DC blocking purposes.
That's what thor.zmt tried to point out: If cap impedance at the desired frequency is far more smaller than load impedance negative influences can be neglected.

 

[abbey road d enfer]

In 2023 i would suggest that EQing and mixing is done in software...

Tell that to Audient, API, SSL...

Cap sound differences and myths about it are a never ending story. IMHO caps have to be selected use case dependent. 4,7 uF in a speaker crossover circuit is not the same as 4,7 uF in a preamp for DC blocking purposes.
That's what thor.zmt tried to point out: If cap impedance at the desired frequency is far more smaller than load impedance negative influences can be neglected.

Do you think I don't know it? Check posts #33 and 127.

 

[Newmarket]

I worked for a guitar amplifier company for many years (mid 1960). After several great projects, I was asked to develop a “VERY CLEAN STUDIO GUITAR AMPLIFIER”. The during the firsts listing tests it was Not Well Liked. THD% & IMD% were very low, damping factor was high (no speaker ringing).

Well yes, in "electric guitar world" "clean" doesn't mean high fidelity.
My particular favourite phrase is "transparent distortion". I know what sort of thing people mean by it - retaining ability to distinguish individual notes etc - but it still makes me smile

 

[Newmarket]

Harman, not Apple, sorry. Check the numerous links to "Harman curve".
Apple is only guilty of following in their footsteps.
See my post #158 there Headphones for Mixing and Mastering
Regarding hearing loss Headphones & Hearing Loss and many others

Thanks. I'll look it up.