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In Reply to: RE: Correction- the supply voltage is a little higher. posted by tyu on March 13, 2014 at 12:01:57
But not in a good 30 years...
Follow Ups:
1) Until I can find the time to replace the LV (low voltage) electrolytic, I will try some larger value film capacitors across the +ve and -ve.
2) When I do replace the large 27,000uF caps, using multiple smaller values in parallel may sound better.
3) The HV capacitors cannot go below 200uF per set as per Ralph. Question; can I raise the 200uF values simply by installing a film cap across each 100uF pair?.
Right now, don't you have three (3) 100uF caps in parallel on each phase of the bipolar HV supply? Any film caps you wire up in parallel with those electrolytics will add additional capacitance, but because the film caps are likely to be small in value compared to 300uF (the net of three 100uF caps in parallel), the film caps won't add significantly. For example, if you use a 30uF film cap, which would have a hope of being audible, the final total capacitance will be 330uF. Some would also bypass the main film bypass capacitor with increasingly smaller value film caps, down to 0.01uF. Some would not.
Lew, if you look carefully at my first picture, you will see there are actually 6 (100uF) caps per phase. 12 in total per amp.
On the right hand side of the HV caps there is a strip of wire which connects all 6 leads together (not noticeable in my picture).
On the left hand side you'll see that 2 (100uF) caps are wired together, and these 'sets' go off in different directions. So, 3 sets of 100uF per phase.
I would install 6 film caps in total per amp. One for each 'pair' of 100uF caps.
I can't see that what you say is true, but you know better than I.
There is no need or reason to bypass pairs of 100uF lytics separately. Any bypass capacitor that you wire in parallel with any electrolytic will be "seen" also by all other electrolytics in the same six-capacitor bundle. (Six per phase, I now presume.)
but sometimes, on my workbench, if the wall voltage is a bit low, I see less than 130V. Don't know whether that's high or low on average.
Anyway, the point was that those Mundorf caps are not up to snuff and that at minimum 150V caps are required but at least 200V is preferred. Does that seem like OK advice? Thanks for the correction on the steady state DCV of the LV supplies.
The B+ is a bit higher. We've put 150V parts in there but they have had a 175V surge rating.
In the case of the Low Voltage 27,000uF caps. We now know they are good for around 175V. This being the maximum surge.
If I change them, as Lew recommends, with a few smaller values per phase, is there any downside to using 500V rated Lytics?.
is form factor- a 500V unit will be much larger for a given capacitance!
Thank you Ralph. I just wanted to make sure there was no 'sonic' downside.
So.................just a gess....you fell the high B+- sounds better??
But the 6AS7 can be driven harder at lower V....umm.............
I know i dont like it above 150V..............gets a littel hard sounding...but i dont like push-pull amp with Tarnsfourmers output ....over 470-80...B+............
Hell it all about the sound...right how we get there......it monky see monky do.....for Diyers anyway....
I well do the work so i can find ....my Sound!...............................thanks
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