Sound differences between cap brands? Test results?

[Steve Conner]

There is a sound that is generated, and it sounds to the ear like a falling note. But a perpetual falling note.

It's called a Shepard tone.

so does it mean that if I hear, say, E and G (which is a minor interval), my ear will generate the C note, and I'm more likely to hear C major chord than E minor?

The otoacoustic distortion is just another kind of intermodulation distortion. If you play an E-G interval on your tube amplified guitar, the amp will be generating that C note already, probably in greater quantities than your ears do. It'll still be at a lower level than the original E and G notes, so you are unlikely to hear it as C major.

Every major key has a relative minor that shares all the same notes, so it isn't as big a deal as you'd think. The E-G interval and the C-E-G triad both fit the key of A minor as well as C major.

The most obvious case of intermodulation is when you hear beat frequencies between two tones close together in frequency, like when tuning your guitar. Even if the two tones were perfect sine waves and the amplifier and speaker were linear, your ears would still generate the beat tone.

[kleuck]

It's a little glib to say that our ears are "tuned to the major scale". We made the musical scales to fit the physics of our ears, just like we make gloves with 5 fingers and T-shirts with one head hole. The ear came first and the whole of music is tuned to it.

Don't think so, did you ever tried to listen at traditional Chinese music ?

[Steve Conner]

Yes. It has a whole bunch of other intervals besides the Pythagorean ones (as does Arabic music and the blues) but it still includes them. The octave, unison, fifth, major third and so on, where the physics of instruments meets up with the physics of the ear.

[guitician]

The tone itself matters little.

You must save big $$$ on your musical instruments.

[Steve Conner]

Not just $$$, think of all the time you save, you can spend it playing instead of tweaking.

[guitician]

instead of tweaking

Never touched the stuff

[overtone]

Did the test. I put my Grados on. I was not alone in bed. I braved distractions. Boots were off.
I did not find out what cap brands are in the test prior to listening, perhaps that was naughty.

This is what i came up with:
1. * (I wrote down something rude)
2. KT
3. TFF
4. Mullard C296
5. Mallory 150

This is an 'orrible test for first thing in the morning.
Findings:
I only got one right
managed to confirm my prejudice to metalized film
should now sell all my NOS valves


So thanks Steve, that was a good start to the day.

[Alex/Tubewonder]

An excellent post by km6xz in its entirety but for this gem:

So what does this have to do with caps? Well, not a lot but any caps that have a non-linear dissipation, or dialectic absorption will change our perception.

I have successfully absorbed idioms and dialectic peculiarities of the west coast variant of the Swedish language.

[Steve Conner]

I have a question for those of you with better ears - the higher-gain clip from the cap comparison has a distinct overtone to each note. Is this the second harmonic?

If you hear a distinct buzzy overtone, it's liable to be a much higher order harmonic, somewhere in the teens. The second through seventh harmonics all blend in with the fundamental and modify the timbre.

The best way to get a feel for what the harmonics do to the tone is to play with the drawbars on a Hammond organ, either real or simulated.

As far as the low-order harmonics go, the even-order ones add a warm, brassy quality while the odd ones give a hollow, woody quality. Some people refer to it as "closed" or "blanketed".

In subtractive synthesis, string and brass patches start with a sawtooth wave, which contains both even and odd harmonics, but woodwind patches start with a square wave, which contains odd harmonics only. However, as soon as the duty cycle of a square wave is distorted away from 50%, the even harmonics appear. The duty cycle of an overdriven tube amp varies quite a lot depending on the amount of overdrive, but many solid-state circuits just give an unchanging 50%. Make of that what you will.

[FredB]

With plastic caps, I've only noticed differences between different dialectic types, rather then between different brands, as in the difference between polypropylene and polyethylene caps.

The same with ceramics. I find I like the NGO/COG type of ceramics sound the best to me. The cheaper ones I think sound grainy.

In contrast to that, I have noticed tone differences between types and brands of aluminum electrolytic caps. I attribute this to differences in the ESR of the particular caps. I've heard although I have yet to try it, that this difference in ESR between types and brands of aluminum electrolytics can be compensated for by paralleling a relatively low value plastic cap along with a larger electrolytic.

[stormbringer]

If you hear a distinct buzzy overtone, it's liable to be a much higher order harmonic, somewhere in the teens. The second through seventh harmonics all blend in with the fundamental and modify the timbre.

The best way to get a feel for what the harmonics do to the tone is to play with the drawbars on a Hammond organ, either real or simulated.

As far as the low-order harmonics go, the even-order ones add a warm, brassy quality while the odd ones give a hollow, woody quality. Some people refer to it as "closed" or "blanketed".

In subtractive synthesis, string and brass patches start with a sawtooth wave, which contains both even and odd harmonics, but woodwind patches start with a square wave, which contains odd harmonics only. However, as soon as the duty cycle of a square wave is distorted away from 50%, the even harmonics appear. The duty cycle of an overdriven tube amp varies quite a lot depending on the amount of overdrive, but many solid-state circuits just give an unchanging 50%. Make of that what you will.

So... in the high-gain clips posted on the metroamp forum, I heard a distinct overtone. Not fuzzy at all, and I'm guessing it is one of the lower harmonics. If you have a chance to listen to those higher-gain clips again, could you let me know (i) if you hear a distinct, musical overtone, and (ii) know what harmonic it is.

high gain clips were available here: https://dl.dropbox.com/u/64682773/Si...ol%20dimed.wav

I'm asking because I built a high-gain project amp with some similar harmonic that was more 'in your face'. An 'ice pick' sort of thing. I hear similar overtones from some 80s metal guitarists (Jake E. Lee, for example).

[überfuzz]

I brought my Hagström Viking to the rehearsal studio today and my amp sounded absolutely delightful. I wonder if someone had changed caps..?

[oc disorder]

Apologies to those I hear groaning as I drag this to the top again but I fell over this and thought it worthy to tag into this thread !

http://www.zedaudiocorp.com/index.php/tech-talk/capacitors-types/item/capacitors.html

"An amusing story: About 14 years ago Zed Audio was building subwoofer amplifiers for a large well known speaker company in Chatsworth California. One of the projects involved a high pass active preamplifier whose output was to be 6dB/octave high pass crossover (same as the circuit above) with some simple elegant electronics. The BIG question came up from management and sound gurus whether one could tell the difference between various high quality film capacitors. I said "no" and I got hammered for this comment. I set up a test where I said they could not even hear a cheap electrolytic, never mind a film type. "You are crazy, full of you know what" were some of the comments I received. So we set up a double blind test. We had a fancy turntable, Audio Research tube preamplifiers and power amplifiers, speaker cable as thick as your arm and all the other high end toys needed for a sound system. Between the preamplifier and power amplifier a two pole switch was inserted and the switch was to select either a dead short or this one penny electrolytic capacitor. I soldered the capacitor to the switch but unbeknownst to the audio boffins, I wired a short across the capacitor so in either switch position they were listening to the same thing – a dead short, a piece of wire! This was going to be fun – I knew that.

The gurus put their favourite album on the turntable and away we went. One of their technicians was flipping the switch at the listeners' command. Back and forth we went for over ten minutes with all saying "Yes that's the capacitor, no that's the wire". So we stopped and I called all these gurus over to the switch and showed them the dead short across the capacitor. Red faces, curses etc and I was a bad boy and they were fools. Most of this "component" sound is in one's head. You have to hear the difference after you have spent $55.00 on your new coupling capacitors!"

And for fun this
http://www.npr.org/blogs/deceptiveca...pick-the-strad

"OK, here's a test. Clip one is a musical phrase from Tchaikovsky's Violin Concerto in D Major. Clip two is the same phrase. The same musician plays both. But one is on a Stradivarius violin, the other on a violin made in 1980. See if you can tell the difference."

"Dale Purves, a professor of neuroscience at Duke University, says the research "makes the point that things that people think are 'special' are not so special after all when knowledge of the origin is taken away."

[Alex/Tubewonder]

It's called " wishful hearing". BTW Mr. Baxandall fell victim to his own very similar test. In his test the switch never chnaged the cap, it was the same one inboth switch positions. The term "wishful hearing" is attributed to him.

[HTH]

I listened to the MetroAmps clips a week or so ago and while the differences are small, they are definitely there - plus I thought the Mallories sounded best.

You could argue this point to death on a similar level about carbon comp, metal film and carbon film resistors and also NOS valves. The point being is that these small differences are accumulative and do make a difference in the tone and feel of the amp once summed.

If you can't hear the difference, thats great for you - less tweaking. If you can (like me), then its unfortunate as you analyse every last thing and the process is much more difficult. Its the last 1% we're all chasing and thats not always by using the most expensive components, its understanding the effect different types of caps and resistors have. I will also admit that changing values has a more dramatic effect, but once again, this is about fine tuning.