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212.30.74.2
Power supply section in my DIY SET amplifier (6c33c tubes)consist of pair 680 uF capacitors per channel. Is there any benefit if I replace them with a pair of 40 uF Mundorf polypropilene ? What could happen with low frequency response ?
Thanx
Follow Ups:
I think the best way is not replace, but add the 40uF capacitor. This should be the last in your PSU (connected to B+). Polypropilene is much faster than electrolytics, so in this position, most of the sound should come from the polypropilene. You can even isolate the poly mundorf more by adding a low resistance in series with it (1 to 4 ohm, for example), and take B+ from the mundorf terminal.
If you replace the 680uF, you get a lot of hum.
...and gotten no answers.JAITI, where are you? Are the caps in series or parallel, AKA do you have 1360uF in one position or 340uF? Or are they separated/connected by a choke? What Voltage is across them? Schematic diagram?
BTW, IMO if you are not able to answer these questions, you have no business sticking your fingers inside a tubed amp containing LETHAL Voltages.
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Tin-eared audiofool and obsessed landscape fotografer.
http://community.webshots.com/user/jeffreybehr
What is in the PS after the 680uF caps? Are the 680 caps in series, or in parallel? If you change them to 40uF, most probably you will get increased hum, unless you have strong downstream filtering. (Large Ls, Cs) You can try taking one of the 680 caps out if they are paralleled, and substitute it with a 40uF good quality cap. That way you'll still have 50% capacitance; you'll get by with that: if your amp is dead quiet now, it can be still very quiet after the mod. If you hear a soft hum, it can become an annoying hum. If you have a soft hum now, and change 2 x 680uF to 40 uF, you will have roof-shaking hum.
jaiti, hi. If the caps now in it are electrolytic virtually anything else would be better - with one exception, Black Gate. I would also look at Unlytics (polyprop) and Solen's polyprop caps in cans. Solen makes a few values - example: 51uF at 630 V. Cerafine would be OK but production stopped some time ago. I don't think Mundorf has a lock on making good polypropylene caps. Also - don't overlook the oil caps. ASC makes some that sound very good. You can find others including paper/foil/oil. The dry polypropylene types can sound excellent. Again, with the exception to Black Gate WKZ, most electrolytics are never optimal. Often I use polyprop (dry or oil) and Black Gates in the same amp - CLC etc. Happy listening.
There is nothing wrong with using electrolytic capacitors in your power supply. Panasonic, Mundorf, Jensen all make fine good quality electrolytics for power supply applications. When properly implemented in a good power supply design the results are excellent.There is nothing wrong with Polypropylene caps and I like the ASC poly/oil caps just fine, but if space is a consideration or you need higher capacitance values in your supply, using electrolytics will not ruin the musical characteristics of the design.
...sounds like not enough capacitance to me. I've replaced 'lytics with 'propylenes in tubed poweramps and gone to about half the value with no apparent ill effects.
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Tin-eared audiofool and obsessed landscape fotografer.
http://community.webshots.com/user/jeffreybehr
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