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#159961 - 2012-02-03 20:19 556 Power-Amp Help
JamesBrennan4 Offline

Registered: 2010-01-21
Posts: 31
Loc: Florida, USA
I have just acquired a 556 power-amp, the amp is functioning fine, but heatsinks remain cold.

How do I remove the top cover?
Are there any bias current or output balance adjustments.
Is it possible to obtain a schematic?
508.20, 501, 541, 561, 505, 555, 556, 557, Allison IC-20

#160026 - 2012-02-05 05:58 Re: 556 Power-Amp Help [Re: JamesBrennan4]
ChrisLayerUK Online   content
President of the Imperial Galactic Government

Registered: 2004-12-09
Posts: 5368
Loc: Colchester, Essex, UK
Hi, if the heatsinks are cold and it is running well, I don't see a problem. The heatsinks are designed to dissipate heat generated so it looks like you are in a very well ventilated position or you are not driving the amp very hard.

Turn it up and see what happens.

You may want to list what speakers you are driving with it.

Just thoughts and a "Bump" for you. Enjoy, Chris smile
No 18 in the Hall of fame smile I have simple tastes; I am content to settle for the best: GIK monster bass panels, rear wall.
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#160070 - 2012-02-05 14:13 Re: 556 Power-Amp Help [Re: JamesBrennan4]
MarkS Offline

Registered: 2003-09-22
Posts: 397
Loc: Wiltshire, England
I used to have a 556, and the heat sinks on mine remained cool.

Mark S

#160081 - 2012-02-05 16:54 Re: 556 Power-Amp Help [Re: MarkS]
JamesBrennan4 Offline

Registered: 2010-01-21
Posts: 31
Loc: Florida, USA
Thank you Chris and Mark for your comments.

Amplifier is driving a pair of Definitive Technology Mythos ST SuperTower (Floor-standing ultra-performance loudspeaker with built-in powered subwoofers).

Sensitivity :93 dB
Internal Subwoofer Amplifier Power :300 watts

Room dimensions are ~ 20' x 22' x 12' high.

Since speakers include subwoofer amplifier, I would agree with both of you that I am not driving amplifier hard.

Rest of system is 508.20 and 541.

Would still like to remove top glass cover and take look at the beautiful craftsmanship. Any guidance or hints would be gladly appreciated.
508.20, 501, 541, 561, 505, 555, 556, 557, Allison IC-20


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