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Old 30th September 2002, 06:52 PM   #21
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Quote:
Originally posted by KaLok
4 pairs toshiba TO-3 per channel
Must different amp then, because schematic shows 5 pairs.
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Old 1st October 2002, 01:39 PM   #22
KaLok is offline KaLok  Hong Kong
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Hi Peter,

Is your circuit is 585? It is 5 pairs per channel and 250W each.
I only count 4 pair each channel????
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Old 1st October 2002, 02:28 PM   #23
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Here's the input stage
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Old 1st October 2002, 02:29 PM   #24
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Here's the output. It says 565 on manul.
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Old 1st October 2002, 04:29 PM   #25
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Peter,

Any idea what the IC is...labeled Adcom 3A?

Thank you,
rt
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Old 1st October 2002, 10:45 PM   #26
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Default Adcom 2A

This is the only marking it has in manual. But I wouldn't worry too much about it and use any other op amp that fits there. BTW, transformer an PS caps are also marked with Adcom code.
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Old 2nd October 2002, 04:10 AM   #27
Chad is offline Chad  United States
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I have An Adcom GFA 5500 does anyone know what the upgrades/downgrades are? Also are there any tweaks that can be done?
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Old 2nd October 2002, 05:47 AM   #28
mlloyd1 is offline mlloyd1  United States
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5500 is a whole different beastie. Can you say MOSFETs? I knew you could. There's some good related discussion in one of the designs on Nelson's site. Maybe it's the A75 amp I'm thinking of? My brain's getting foggy again.
By they way, Adcom sells service manuals that have schematics in them. Great for study. Gotta' have something fun to read when I'm old(er) and crotchety.

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I have An Adcom GFA 5500 does anyone know what the upgrades/downgrades are? Also are there any tweaks that can be done?
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Old 2nd October 2002, 09:52 AM   #29
djk is offline djk
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The GFA585 looks just like the 565, just half the number of outputs.

" I ran my 555II bridged @ 1ohm "

You're very lucky, mine have much heavier drivers and two 105CFM fans and the transformer cuts out when driving less than 8 ohms in mono.

What did you do about the fuses? The stock fuses will open up at 50W into 1 ohm.
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Old 2nd October 2002, 03:38 PM   #30
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--" I ran my 555II bridged @ 1ohm "

--You're very lucky, mine have much heavier drivers and two
--105CFM fans and the transformer cuts out when driving less
--than 8 ohms in mono.
--What did you do about the fuses? The stock fuses will open up
--at 50W into 1 ohm.

At 1 ohm, it was only driving tweeters, hardly any current draw.
I had an additional fuse at 3/4 amp to protect all the ribbons.

I didn't change the stock fuses. Recently I'm doing some listening tests with my Lambda 15" woofer, 4 ohm. The amplifier fins start
heating up after a long while but it works. I push it to mild
clipping. I've also connected another 8ohm midrange in parallel with the 15 when doing 200hz - 2.5khz tests.

So not all 555II can do this? I have the Voodo model ? heh

This is an Ebay amp, I don't know if the previous owner(s) did any mods, but looking inside it seems stock.
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