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Denon POA 6600 Thread

Here is a KSA3503DS. This is what replaced TR502, 503, 507, 509 and 523.
KSC3503DS-0.JPGKSC3503DS-1.JPGKSC3503DS-2.JPGKSC3503DS-3.JPGKSC3503DS-4.JPGKSC3503DS-5.JPG

As I mentioned earlier all of the replacement trannys came in batches of 50 or more and were very consistent in hFE. So the entire sets are all matched.
While matching transistors that are not working in pairs most likely doesn't do a bit of good it was easy to do, I had the time and I'm sure that it can do no harm.

Besides, it made me feel good. I'm sure that that good feeling plus €1.50 will be enough to buy a bottle of beer the next time that I go shopping.

Cheers,
James
 
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We are getting close to the end for today, 2nd from the last is TR508, a 2SA1321.
TR508-0.JPGTR508-1.JPGTR508-2.JPGTR508-3.JPGTR508-4.JPGTR508-5.JPG

Cheers,
James
 
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Perhaps tomorrow I'll display some of the output section but for today I am just all used up.

Cheers,
James
 
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The first test run with music was a success.
DSC02520.JPG

The Marantz MA500 pair in the right channel have more gain, I had to turn off pure direct and turn the balance 2.5 points to the left. Not really a surprise with the MA500 bridged and effectively driving a 2 ohm load.

I only listened to one CD, John Mellencamp's Lonesome Jubilee.

First impression, the Denon is very clean, the Marantz has more midrange emphases. But the Denon didn't display any bad habits. Vocals and acoustic guitar are very clear and clean. I listened at a "spirited" volume. By the end of the CD the MA500's were starting to get a bit hot, the POA 6600 was lightly warm.

This motivates me greatly to get started on the next amp but I have a few things to do today and tomorrow, shooting for Wednesday to get the amp on the bench.

DSC02521.JPG

Cheers,
James
 
Before I closed up the amp yesterday I did one quick test.

Previously when I installed a TL082P in the IC501 position it pulled the supply voltages down to +/-14.9v. I interpret that as oscillation drawing too much power and pulling the rails down. (the NJM082BD has a fT of 3MHz & 13V/µs, the TL082P is 5.25MHz & 20V/µs)

So I stuck it in again and now the supply voltages hold steady at +/- 15.2v. So I'm thinking that things are looking better concerning using a better op-amp.

I looked through my stash and found a pair of OPA1656. They are a SOIC package so I'll have to mount them to adapters but that will only take a few minutes. They are FET input op-amps. 20MHz & 24V/µs might be pushing it.

Cheers,
James
 
Bratwurst7s said:
By the end of the CD the MA500's were starting to get a bit hot, the POA 6600 was lightly warm.
Click to expand...
Don't spill your brew on it
Bratwurst7s said:
I looked through my stash and found a pair of OPA1656. They are a SOIC package so I'll have to mount them to adapters but that will only take a few minutes. They are FET input op-amps. 20MHz & 24V/µs might be pushing it.
Click to expand...
Lot's of nice op amps on the market nowadays. I choose the one that sounds good & doesn't get hot.
Technical and stuff.
 
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I wish I had more to contribute than just, "good work", lol. I just sit back and watch people who actually know what they're doing show the work.

I've never actually had a power amplifier myself; it's always been integrateds or an odd receiver here or there. I'd like to one day, though. I know very little about them.
 
analogwisdom said:
I've never actually had a power amplifier myself; it's always been integrateds or an odd receiver here or there. I'd like to one day, though. I know very little about them
Click to expand...
I always thought power amps were the best to work on as a newbie. I won't claim pro status either. Usually 30ish caps on the models I 've serviced. Pre-amps & receivers though were alot more involved. 80+ caps makes for a long boring day.
 
analogwisdom said:
I wish I had more to contribute than just, "good work", lol. I just sit back and watch people who actually know what they're doing show the work.

I've never actually had a power amplifier myself; it's always been integrateds or an odd receiver here or there. I'd like to one day, though. I know very little about them.
Click to expand...
I started out with separates, a Yamaha C-50+M-50. Then went to an integrated for 20 years, an AX-1090. Then back to separates. And now even more separate.

I would not willingly go back to an integrated. Channel separation and sound quality is just better with a dedicated pre and power amp. Going to mono power amps has been a revelation. Trust me, it will give you a Chubby.

Receivers never interested me at all. Radio just takes me to that thread about being angry all the time.

:beerchug:,
James
 
Soundscape said:
Was this the Denon that had a two foot power cord on it? I'm still getting your Denons confused.
Click to expand...

That was one of the Marantz MA500. That tail was only 9" long. I'm getting confused too, I have 6 of the MA500 and 3 of the POA-6600.

I'm going to open up 2 of the MA500's in a few minutes and swap out the NJM2068DD in the signal inverters with LME49720's.

James
 
I am approaching this second amp a bit different from the first one.

I am going to rework the front panel board first, then the input selector board and third the power supply.
That will let me get all of the major dissasembly and re-assembly of the major portion of the amp rather quickly and let me concentrate on the amp board last. I have already replaced the speaker terminals.

As with the first amp I put a piece of tape on each connector with a not of the CD number and board that the plug inserts into.
DSC02528.JPGDSC02529.JPG

There are wire looms snaking all through the amp and it is easy to loose track of not only where they co but how they were routed. I take a lot of photos.

Cheers,
James
 
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