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Old 25th November 2012, 08:32 PM   #331
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Well actually, you only want as much DC across a 'lytic as is necessary to keep it in good working order. At higher voltages, distortion actually increases, as Cyril Bateman found. Introducing some DC offset should be easy in the JLH, as it requires some offset trimming anyway.

Basically the largest disadvantage of using coupling caps is their size. Ideally you're looking at something like 1000F per channel.
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Old 30th November 2012, 06:29 PM   #332
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I have the blue PCB and has nothing to do with the green. The blue remains perfectly the offset about 10 mvolt or so.
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Old 1st December 2012, 01:30 PM   #333
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Blue PCB:

On a hour, the offset is constant, around 15 mVolt more less. The sound is good. I think that the board desing (the path of the track and its travel is totally different) and the quality component is the differece.

I think that the green board "JHL" its a c***p...
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Old 1st December 2012, 08:13 PM   #334
bkercso is offline bkercso  Hungary
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I built 2 blue ones and during warm up the offset changed ~100mV at both amp.
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Old 2nd December 2012, 12:02 PM   #335
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On Maxs unit, when start, the offset is ~180 mVolt and down to 10~30 Volt after 1 hour.
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Old 2nd December 2012, 07:55 PM   #336
bkercso is offline bkercso  Hungary
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I used 4x1N4148 per channel as recommended in this topic, and trimpot.
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Old 4th December 2012, 09:06 PM   #337
oz7aff is offline oz7aff  Denmark
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Is that instead of the 2V7 Zenerdiode ?
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Old 4th December 2012, 11:41 PM   #338
bkercso is offline bkercso  Hungary
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Yes.
Oh, sorry! Only 3x1N4148 per channel.
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Old 5th December 2012, 08:39 AM   #339
oz7aff is offline oz7aff  Denmark
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Ok, I think one could also try to use a LED instead.
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Old 5th December 2012, 09:18 AM   #340
bkercso is offline bkercso  Hungary
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LED has more noise than 4148. Red LEDs are less noisy than others.
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