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    Building, troubleshooting and testing of these amplifiers should only be
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On the cheap..Best coupling cap

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#42
#43
This thread is making me want to wire up a make before break rotary switch to flip between 6 different capacitors in real time, with headphones to eliminate all room variations. I suspect that if a person can flip capacitors fast during a trumpet or bass solo, if there is anything to this, it will uncover the differences. I suspect there won't be much difference. Waiting an hour to change a cap between auditions I really think the listener would be fooling or convincing themselves of appant change. The overpriced audio industry depends upon the silence between auditions, in that silence is where fools convince themselves to spend more. I'm a firm believer in "fast flip" A/B testing.
 
#44
Windcrest77 said:
This thread is making me want to wire up a make before break rotary switch to flip between 6 different capacitors in real time, with headphones to eliminate all room variations. I suspect that if a person can flip capacitors fast during a trumpet or bass solo, if there is anything to this, it will uncover the differences. I suspect there won't be much difference. Waiting an hour to change a cap between auditions I really think the listener would be fooling or convincing themselves of appant change. The overpriced audio industry depends upon the silence between auditions, in that silence is where fools convince themselves to spend more. I'm a firm believer in "fast flip" A/B testing.
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#46
GoatGuy said:
Like this...
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Thanks! Obviously I'm not the first one to want to do this. I didn't think of a pre-charging arrangement was necessary to keep it from popping. just a "make before break" rotary switch that would momentarily wire adjacent caps in parallel before the contact releases the previous cap. I thought that might be enough contact time to smooth the transitions. It would be a cute little device in a small extruded box with binding posts to install the test capacitors onto. Mostly for trying different value capacitors sonically if not comparing pricey ones of the same value.
 
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#50
Windcrest77 said:
Thanks! Obviously I'm not the first one to want to do this. I didn't think of a pre-charging arrangement was necessary to keep it from popping. just a "make before break" rotary switch that would momentarily wire adjacent caps in parallel before the contact releases the previous cap. I thought that might be enough contact time to smooth the transitions. It would be a cute little device in a small extruded box with binding posts to install the test capacitors onto. Mostly for trying different value capacitors sonically if not comparing pricey ones of the same value.
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You're welcome.

If you want to really blow people away, replace the rotary switch (which still includes easily observable confirmation-(of one's choice)-bias, with individual low-signal relays. As in ( EA2-5NU KEMET | Mouser ) for a buck-seventy a throw. Six of them often less expensive than a quality rotary!

But of course one still has the how-to-select-a-relay problem.

That is answered almost trivially with a Arduino-on-the-cheap microcontroller. “Teensy” also a good choice. A bunch of push-buttons to 'choose' one of the many under test, plus 'R' for random choice and '>' for next in line. Probably could cobble together the whole thing for less than $50 … all-in-except-for-the-burnished-unicorn-horn capacitors. Trick would be NOT to have indicator lights on top. Ruins the "R" functionality.

Seriously - everything is made “more fun” by incorporating microcontrollers and homebrew experimentation techniques such as this. The “tube-steam-punk” part is interesting, but pretty long-of-tooth. But microcontrollers, well … sparks the creative energy!

Just Saying,
GoatGuy ✓

EDIT … oh, oooh… no, do have the indicator lights on top! Just arrange than when pressing "R", that they go out, none light. To find out which random choice made, press R again, and a 1-second lighting of the as-randomly chosen previously lamp would happen. Then it'd change to another random selection. Wow… that'd REALLY be helpful. You could listen for as long as you'd like to 'make an evaluation', then find out what capacitor was actually under test, trivially.

That's the thing about programming (my lifelong profession). Its almost trivial to “add cool features” in software that would be almost impossible to inexpensively cobble without the microcontroller. Just saying…
 
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#52
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#53
#56
Short of using ceramic caps or electrolytics (too leaky for tube stages), it doesn't matter.

Replace any old paper caps. They do sound different because they are DEFECTIVE. Bathtub PIO caps are usually fine, but you almost never see them in audio gear.

Orange drops are nice because the casing doesn't melt with a soldering iron quite so easily. Usually I just throw some of the yellow illanois capacitor (MPW?) caps in and call it a day.

The only time I would recommend using expensive caps is in something like a McIntosh or a Citation II where a future buyer might care, but if you are building for yourself realize that they all sound about the same.

Only time I've ever used expensive caps is when I salvaged some 1uF Wonder Caps out of an old amp that a buddy had made sometime in the late 80s or early 90s (it had a blown output xformer that I couldn't get so I wound up scrapping it).
 
#57
azazello said:
Russian FT-3 !!
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As much as I would like to try them I simply don't have room on the circuit board. They are too long and too large a diameter to work for me. Besides nowadays they are $9 and when they first started selling them they were $1 ea if memory is correct. If nothing else I don't think I would be doing myself much good installing a 1960's cap in place of a 1950's cap.
 
#59
Burnedfingers said:
As much as I would like to try them I simply don't have room on the circuit board. They are too long and too large a diameter to work for me. Besides nowadays they are $9 and when they first started selling them they were $1 ea if memory is correct. If nothing else I don't think I would be doing myself much good installing a 1960's cap in place of a 1950's cap.
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They are a nice long life part of good quality, but I would buy something modern now that they are ~9$ each.
 
#60
Windcrest77 said:
This thread is making me want to wire up a make before break rotary switch to flip between 6 different capacitors...
Click to expand...

Just do it. I've already a quick RCA - rotary switch - RCA wooden panel board. You can connect the capacitors behind the panel, that way you won't see which capacitor is which. You can type down each rotary switch position and if you can hear a difference, listen to long term differences, and write down observations. Give it a few days of playing around, switching positions, then look over and discover which capacitors you liked the most.
 
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