Monifying a Denon POA-800

[roibm]

Hello guys... great job you're doing here...

So, let's see...
I have bought a Denon POA-800(power amp) from ebay, I don't know exactly how old it is but I would expect 8 years. Compared to my Denon AVR-1802(receiver) it sounds much better(using Denon or the analog outputs of my Audiophile 2496 as a preamp), and I was wondering if I could make it even better...

Near the inputs I could see an opamp(6458D / 1F0). I searched the web and didn't find many things about it, so don't know about it's quality. I think it is built by Sanyo. Do you guys know anything about it? Do you think it is worth upgrading it to a better opamp?

Also, there are 2 caps 10000 uF at 50V made by Marcom, rated up to 85C(temperature). Considering the age of the amp do you think I could get any advantage upgrading them?

BTW, the amplification stage is using 2SA1302/2SC3281


Thank you so much...

 

[Jan Dupont]

I have had some POA's over the time, and I can say one thing for sure:
Put larger caps (2x22.000uF or more) in the supply if you want it to have a fair bass response

 

[roibm]

Hey Jan, thanks for your fast answer

So, I should be changing this caps... Good to know.
Any recommandations what to use? Brand? I suppose this change doesn't imply any other change... am I right?
What about that opamp? Do you think changing it for one of the best opamp these days, will this make any difference?

Thanks...


And for the mods now, if you can change the subject of the thread, it should read be like "Modifying a Denon POA-800". Thanks.

 

[Jan Dupont]

I don't recall the name of the new caps I used, but as I recall they where quite ordinary from the local cap-pusher ..
Before I changed these, I had the problem that the protection system got activated because the rail voltages dropped during high power peaks.. Afterwards there was no problems

I never changed any opamps in my POA's, however i recall that I have replaced some small capacitors in the input section to better types..........

Do you have the schematic for the POA-800???

 

[roibm]

No, I don't have the schematic
But I can take some pics if you would like...

Do you remember somehow the size of the caps you used? I am constrained to 30x60mm, not that much space over there...

 

[Jan Dupont]

You are right... Thats not much space, however if you do a searh at RS-Components or others component resellers you may come across some caps with more uF that fits

 

[roibm]

^bump^

anyone? please...

 

[JNTIT]

Morning, I just picked up a Denon POA 800 and was looking for some info. I have the same problem no room for larger caps. Could I mount them externally and solder the leads to the board? Thanks John

 

[Jan Dupont]

Morning, I just picked up a Denon POA 800 and was looking for some info. I have the same problem no room for larger caps. Could I mount them externally and solder the leads to the board? Thanks John

Yes you can. Leave the originals in and just add more capacistance internal or external......

 

[JNTIT]

Thanks for the info

. I'll start looking for some 22,000uf caps with a little more voltage. Thanks again John

 

[Jan Dupont]

As I don't know the 800, make sure that the rectification bridge can handle the inrush Current with the additional caps....... Or you could just add 10.000uF caps

 

[yakimaman1]

I have had some POA's over the time, and I can say one thing for sure:
Put larger caps (2x22.000uF or more) in the supply if you want it to have a fair bass response

Jan...the website that you gave for getting a service manual for the Denon POA-800 DOES NOT WORK. That particular service manual is NOT available from them in Denmark.
Dr.Doug