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Old 23rd February 2004, 07:31 AM   #61
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Default DC filter

Hi,

I use two diodes and a 4700µF 16 V cap... works fine. There is no need for a high voltage cap since the maximum DC they can "see" is about 1 V.

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Old 23rd February 2004, 07:43 AM   #62
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Default Re: DC filter

Quote:
Originally posted by JensRasmussen
Hi,

I use two diodes and a 4700µF 16 V cap... works fine. There is no need for a high voltage cap since the maximum DC they can "see" is about 1 V.
I imagine that higher voltage caps are a little bit more heavy duty but in this case I have made room for just about about any cap.
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Old 15th April 2004, 06:30 PM   #63
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Phew... finally quiet 1KVA toroids used two 2200uF caps, two diodes, one varistor and a 0.33uf cap. Combined with a slow-start circuit ( http://mitglied.lycos.de/Promitheus/...or_toroids.htm ) it made my amps ready for case placement (ok, after I change only a couple of things I have planned
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Old 17th April 2004, 08:20 AM   #64
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Default line filter effect?

It could be just my ears and my brain that's playing tricks on me, but I also noticed a tonality change, also present after I switched to 4x4700uf caps instead of 2x2200: the bass is more thin than before and the mids and highs are somehow clearer (better decay & less 'background' noise), but everything's not as punchier than before. Did some more reading around here, and that seems to be the general effect of power line filters/conditioners (higher impedance on trafo primaries? ).
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Old 17th April 2004, 06:02 PM   #65
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maybe the missing bass and improved mid resolution is due acoustically to the transformer hum/buzzing being gone ?

mlloyd1
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Old 17th April 2004, 06:13 PM   #66
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Quote:
maybe the missing bass and improved mid resolution is due acoustically to the transformer hum/buzzing being gone
Ehm, no. I recently applied a dc filter to my GC which never had any hum at all. The sound definitely changed and it took me a long time and many switches back and forth to finally make up my mind that the change is after all for the better.

Of course there is no perceptible change in the impedance on the primaries, at least not at 50 Hz.
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Old 17th April 2004, 10:33 PM   #67
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Quote:
Originally posted by mlloyd1
maybe the missing bass and improved mid resolution is due acoustically to the transformer hum/buzzing being gone ?
200W Slone OPTIMOS amps + large floorstanders; bass is flat down to the low 30Hz region (-1dB in specs - not in room ... so I don't think so

The toroids did not buzz at all times, but when a neighbour decides to plug in god-knows-what-crappy-device-that-makes-me-nervous-because-there-is-DC-offset-on-the-mains-and-things-buzz.

However, there's definetely a change in the overall sonic character
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Old 19th April 2004, 07:35 AM   #68
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Found out the culprit: it was a 330nF MKT mains rated caps connected across the primary for 'HF' filtering... grr...

I absolutely hate metallized polypropylene or MKP or MKT caps ... I seem to get gutless, reduced dynamic, congested, constipated sound - even cymbals sound thin with those wherever I happen to (use) them: mains filter , DAC PS bypass, amp PS bypass, speakers... they're totally for music.

Had far much more success with mylar caps for bypass/decoupling sonic-wise.
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Old 22nd May 2004, 02:34 PM   #69
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Eva,

You said, two 1000uF and some diodes, which diodes rating are you using and in what configuration?
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Old 22nd May 2004, 04:07 PM   #70
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How much DC on the line can cause a transformer to hum?

Mine hums, but I only measure -53mV with my DMM (yes, always -53mV even if I swap the wires)
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