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Old 14th July 2010, 12:53 AM   #1781
mdynac is offline mdynac  United States
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oh yeah
ima chuffin' baby,
ima chuffin'.......
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Old 14th July 2010, 10:13 AM   #1782
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Default hum

Quote:
Originally Posted by Salas View Post
We have no reports here about such an incident before. If your amplifier has capacitor input you can hardwire the relay signal points always on. Without info I can't guess your system. Do you use BC517 for driving the relay?
Sorry for late response.
I use BC546 for driving relay.
My System : Player<->DC B1-with shuntreg<->Gainclone 3886.
There is no hum when GC power ON and DC B1 still OFF, but after DC B1 ON and relay still OFF, i heard hum loudly.

tq
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Old 14th July 2010, 11:30 AM   #1783
Salas is offline Salas  Greece
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You need BC517 in case you hear any strange mechanical noises from the relay.

The solution for you is in the pages 177-178. Do that grounded cross mod and it will not interact again.

But the steady recommendation for any system from stadium PA to home, is we turn on the power amp last and we shut it down first. To turn on/off any device before it when power's on is risky anyway. So when you will do that Oenboek's mod don't forget and go on/off all the time with the power amp on just because there will be no tell tale noises.
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Old 14th July 2010, 05:20 PM   #1784
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Ok, so I dropped the output impedance of the DCB1 to 470R from the 1K as the 1K was just a little too flat (the amp input impedance is 7k). While I was at at I decided to put in the 3.5ohm resistors. I measured for current and got 177mA/215mA. Any idea why this would be? I checked last night and then again this morning. The resistors are definitely 3.5 Eagle...

One side of LEDs (negative) is definitely brighter than the other now.
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Old 14th July 2010, 07:39 PM   #1785
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Disregard idiot statement above. I was still dividing by the 10ohm value. The current is ~505/614mA. It pays to be awake when you do math.

It does get a bit hot, but since the whole enclosure is the heatsink I think it will be manageable. However, I will probably drill a hole and power a fan with a wall wart since the classdaudio amp also gets quite hot with its heatsink.

That said, based on listening last night and this morning, this is the best my DCB1 has sounded. Will evaluate further tonight, but with increased current beyond 250mA, perhaps the returns aren't quite as diminished after all...
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Old 15th July 2010, 07:19 AM   #1786
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Default hum

Quote:
Originally Posted by Salas View Post
You need BC517 in case you hear any strange mechanical noises from the relay.

The solution for you is in the pages 177-178. Do that grounded cross mod and it will not interact again.

But the steady recommendation for any system from stadium PA to home, is we turn on the power amp last and we shut it down first. To turn on/off any device before it when power's on is risky anyway. So when you will do that Oenboek's mod don't forget and go on/off all the time with the power amp on just because there will be no tell tale noises.
Thanks salas,
Last night i try upgrade grounding system of power source (line) and suddenly everything is quite just like "coffins ".
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Old 15th July 2010, 07:53 AM   #1787
Salas is offline Salas  Greece
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Whatever. I did not experience it myself either nor it was picked up by the numerous proto testers. Something in some systems must be exaggerating it. Maybe grounding too as you say. Keep in mind the solution mod if it appears again with some other partner equipment though. Thanks for reporting.
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Old 15th July 2010, 04:34 PM   #1788
Malka07 is offline Malka07  England
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Just want to report, that i have been runnning the dcb1 for a couple of days now since i did the grounded cross mod, and everything is fine, there are no problems to report with this mod, so if anyone is experiencing hum(buzz) when powering down the dcb1 while the poweramp is on, then as Salas say "The solution for you is in the pages 177-178" plus you get the advantage that it takes the relay out of the signal path
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Old 15th July 2010, 04:53 PM   #1789
Salas is offline Salas  Greece
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Cheers.
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Old 15th July 2010, 06:38 PM   #1790
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Quote:
Originally Posted by Malka07 View Post
... Salas say "The solution for you is in the pages 177-178" ...
Would it be too much to ask for Post #s instead of Page #s - some folks elect to have more posts per page.

Thanks,
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