mods for the ADCOM 565 monoblocks

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K

K-amps

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Joined 2003
lopan said:
Any one out there tried modifying an Adcom 565 amp. Mine just drive the subs but been thinking of tearing them down. Wanted to hear if any one has tried this and would lend his expertise or tell his experience.

Thanks
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I have modded the 555II's with excellent results. But the 565 is too fussy. I'd say plan out carefully what you want to do. The 565 is pretty souped up as it is. However I have successfully bumped up the DC rails to +/- 90 vdc which gave me over 460 watts into 8E RMS. At 4 ohms, I got over 650 watts. I used dual 1kVA toroids (2kva per monoblock) to get that power rating.

I did need a small (noiseless) fan running over the VAS circuits and regulators to keep em cool.

However I did not mess with the topology in any other way.

"Tim the Toolman upgrade" :whazzat:

With the 565 having 20 of the 150w Toshiba OP devices, you could actually run the OP stage separately with +/- 100vdc @ 8 ohm loads with no problems. (Yes I know the TOS OP devices are rated for 180vce but they have been known to run with +/- 125vdc rails at low currents. ) but try this at your own peril! :hot: You will however get about 600watts RMS into 8 ohms if the circuits are kept cool enough.

I would like to point out, the amp will not be as reliable as before; you will be running all circuits closer to maximum, and you should engage in this with the knowledge that you could fry a decently working amp. ;-). I would do this just to play around, not as a permanent jig.

:D
 
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markp

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Joined 2003
You can also do a power supply film cap bypass. Put some good quality polyprop film caps in parallel with the main PS caps and accross the local electrolytic caps on the main pcb. This can give it clearer mids and highs. I've done it on 555mkIIs and liked what I got. It's a cheap upgrade too.
 
K

K-amps

Member
Joined 2003
markp said:
You can also do a power supply film cap bypass. Put some good quality polyprop film caps in parallel with the main PS caps and accross the local electrolytic caps on the main pcb. This can give it clearer mids and highs. I've done it on 555mkIIs and liked what I got. It's a cheap upgrade too.
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In that vein, Blackgate N types won't harm either will they?


:)
 
L

lopan

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Joined 2004
thanks

thanks -- some good information -- I don't think I ever run out of power as the clipping lights never blink. My load is a nominal 3 ohms 2 Dynaudio 30W-100 per side in parellel. And they're crossed overat 65 hertz so not much midrange here.

But I could definitly do some bypass caps and possibly upgrade/replace all the power supply caps. Maybe upgrade the bridge configuration and the power cord could be 12 gauge.

Probably should get the schematics and PCB layout first.
 
W

WithTarragon

Member
Joined 2007
markp said:
You can also do a power supply film cap bypass. Put some good quality polyprop film caps in parallel with the main PS caps and accross the local electrolytic caps on the main pcb. This can give it clearer mids and highs. I've done it on 555mkIIs and liked what I got. It's a cheap upgrade too.
Click to expand...

Mark, I believe this is already done on the 565s, 585s, and 555s (some of the mk 2 versions). I

t probably does not hurt to replace them since these bypass PS caps seem to have a short life.
 
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