Maybe i'm stating the obvious, but you probably have a separate adjustable regulated powersupply.
Why dont you disconnect all but the centertaps of the OPT's, and move them over to the separate supply.
Then see if connecting and disconnecting the film caps still has so much influence....
Greetings, Paul
I think we may be saying the same thing, but using different language.
At low and mid frequencies the bypass has a higher impedance than the main cap, roughly 100 times higher. Therefore it won't have any effect.
At higher frequencies the main cap impedance levels off and then begins to rise. Eventually, it will have a higher impedance than the bypass. I'm not sure whether this happens at 10kHz or 100kHz (it depends on the quality of the electrolytic), but it will be at or above the top end of the normal audio range. Only in this region could the bypass do anything useful.
In an SE amp with a common PSU (which I think is the configuration used?) the bypass might improve channel separation in the upper HF region. Not by some magic involving transient power demand (HF transients are low in energy), but simply by keeping the PSU output impedance low so reducing cross-talk. A little bit of cross-talk would be difficult to measure, but easy to hear on a stereo signal.
This effect would be much smaller with PP, and disappear completely with separate PSUs or at least separate smoothing caps. It could be worse with some combinations of low ESR electrolytics and bypasses, as there could be a resonant peak in impedance.
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he he he he
I am wondering how 'bad' a large electrolytic has to be in order for a bypass cap to be noticeable. Instead of just looking at the bypass, we should consider the possible variation in quality between the electrolytics we are using.
U guys have been using the wrong 'lytics. Try these: http://www.cde.com/catalogs/MLS.pdf
Copper leads, low ESL and ESR, extreme life (100years), handles high altitude...
The only 'lytics approved for use in fighter jets!
Copper leads, low ESL and ESR, extreme life (100years), handles high altitude...
The only 'lytics approved for use in fighter jets!
he he he he
I am wondering how 'bad' a large electrolytic has to be in order for a bypass cap to be noticeable. Instead of just looking at the bypass, we should consider the possible variation in quality between the electrolytics we are using.
As somebody noted, you use the 6AS7 in your amp. No wonder you can't hear an improvement. Even the worst possible crapcap can't affect your amp. Try a 2A3 and perhaps other members will start to take you seriously.
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They actually show up surplus at hamfests around here, and I have used them - they seem fine if singularly unexciting. (I guess that is pretty much what you want in a supply capacitor..
) And no worries about them wearing out if run within ratings..
As somebody noted, you use the 6AS7 in your amp. No wonder you can't hear an improvement. Even the worst possible crapcap can't affect your amp. Try a 2A3 and perhaps other members will start to take you seriously.
You need to ask about speakers and sources, and FWIW I have heard some good sounding 6AS7 PP amps in the past.
Problem is, these lytics only take up to 250V.... hehehe...way below Wavebourn's 800V... unless you plan to serialise a large number of them...
Take that serial capping into a failure of one cap. If you want a bomb in your amp just serialise some low voltage caps to get it to work with higher voltage and let one fail with a short into the other one. It won't blow a fuse until the cap explodes. And a big cap explodes in a big way.
The two best amps I have ever built were 6AS7 PP, and others have agreed with that conclusion.As somebody noted, you use the 6AS7 in your amp. No wonder you can't hear an improvement. Even the worst possible crapcap can't affect your amp. Try a 2A3 and perhaps other members will start to take you seriously.
I hate to see unfounded snobbish prejudice. I feel certain you have never heard a well implemented 6AS7 PP amp or you couldn't make such an ignorant comment.
I would go so far as to state that a Class A triode PP has intrinsic superiority over almost all SE amps, but I bet you haven't heard one of those either.
Shoog
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Commonly done, as the highest voltage electrolytics are commonly rated at not much more than 500 - 550V. I've never had a problem doing this that I have not also (much more frequently) encountered with single caps as long as the caps are normally operated properly derated. And yes it is messy, and that's why you should put them inside a metal chassis with a bottom cover..
Personally I'd rather have two good 350V/400V snap-ins with proper equalizing resistors in series than a single 500V cap at voltages above 450V - much more reliable and long lived IME..
Safe bet I guess, and while I prefer SE amps based around DHTs, I have heard a couple of very nice sounding 6AS7 based PP amps. Having designed and built a lot of SE and PP amps over the years I probably would take small issue with you last comment, but to each their own. Both can work well within the context of the system they were designed for.
The particular 6AS7 amp mentioned might be SE and those are a tougher nut to crack. Sources, and speakers in particular are an important element in these sorts of evaluations. WRT to cathode bypass caps I can hear all sorts of things going on which is why I mostly use fixed bias or LEDs or at worse unbypassed cathode resistors where the increased noise and rp are not an issue.
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I'm with Kevin on choice of voltage ratings. The 250V and below versions (Nichicon, Panasonic, etc) have better specs than the 450v types. Specifically, better temperature degradation of impedance with cold temperatures.... and if your weather is anything like ours now (-5 deg C daytime, freezing fog), this may be worthwhile.
A fuse in the HT circuit, before the caps, is a good idea. They do go bang spectacularly! The Elna Cerafines, which are a better sounding Elko, fail short-circuit in my experience.
In any event, the lifetime of electrolytics is poor - and they sound bad before you can measure anything wrong with the ESR or C value.
A fuse in the HT circuit, before the caps, is a good idea. They do go bang spectacularly! The Elna Cerafines, which are a better sounding Elko, fail short-circuit in my experience.
In any event, the lifetime of electrolytics is poor - and they sound bad before you can measure anything wrong with the ESR or C value.
Don't want to spoil the fun but
I think he's pullin yer chain. There's another thread where the "linearity" of 6AS7s is being called into question. SemperFi builds 6AS7 amps...
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