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Onkyo M504/P304....why can't I enjoy this??

I had an extremely nice/powerful Onkyo Integra Japanese release only Integrated amp. I wanted to like it, and I did in some ways, but it was too flat/dead/clinical/lifeless/insert description of dissatisfaction here. I finally traded it for a Sansui 8 (which turned out not to work) which I gave away. That Onkyo was so well built and it looked great. It was amazingly powerful but it just could not make the cut.
 
I looked over the schematic
http://www.eserviceinfo.com/downloadsm/49473/Onkyo_P304.html

And leestereo is right. These 'are' lower line amps as he noted and much better quality is avail these days. Might look at replacing the few caps in the tone circuit but I'd lay odds on the op-amps will make a big improvement. If you can't do the work wouldn't take long for a tech to replace them.

IC''s Q301,Q302 use NJM4558DBX note a & b i.e. 2x each 301a and 301b
IC's Q551,Q552 use NJM4558D note same as above.. a & b

=================
Lee I looked over your posts and very descriptive and the mods were pretty simple for your project.
 
Binkman said:
I looked over the schematic
http://www.eserviceinfo.com/downloadsm/49473/Onkyo_P304.html

And leestereo is right. These 'are' lower line amps as he noted and much better quality is avail these days. Might look at replacing the few caps in the tone circuit but I'd lay odds on the op-amps will make a big improvement. If you can't do the work wouldn't take long for a tech to replace them.

IC''s Q301,Q302 use NJM4558DBX note a & b i.e. 2x each 301a and 301b
IC's Q551,Q552 use NJM4558D note same as above.. a & b

=================
Lee I looked over your posts and very descriptive and the mods were pretty simple for your project.
Click to expand...

Leestereo and Binkman, Thank So Much!! I would LOVE to pay someone to do this. This piece is a cornerstone of my marriage....we joke about it, and while it would be easy to snag one of those good looking Yamahas (they have a LOUDNESS, which is what I think this onkyo SERIOUSLY needs) I'd much rather take it to the next level, if for no other reason than the lengths my wonderful wife took to procure it.

Any takers?? I've had AK jobs from Kansas City, recaps from Delaware, great bunch of very intelligent techs here. I, unfortunately, am not one of them. :no:
 
Those op-amps are for the servos. Replacing them will make a difference, but probably not as much as you want. There are also 2 back to back 22uf/25v caps in the servo circuit that could be replaced with a bipolar while you are at it.

I have a P308 hooked up to a POA-2400 right now. It sounds so-so compared to a Aleph P or Kyocera C-910.
 
As Binkman said, its a very simple upgrade; the op amps I used are readily available from Mouser and it should take no more than 1 hour of so of bench time with a decent tech. Resist the urge to use boutique op amps, you risk oscillation with these ultra high slewing op amps; the NJM2068 (line amp) and NJM4580 (phono amp) are excellent. Here's a link to a very good debunking of op amp myths: http://nwavguy.blogspot.ca/2011/08/op-amps-myths-facts.html
 
Leestereo, I'm going to keep this thread in my email, and have that done when I find a suitable tech. I'm finished with my usual repair center in Nashville, too many cases of tomfoolery, bad work, and generally unfinished jobs that cost as much as double what was quoted.

I keep promising Mattsd that I'm going to pay him a visit one day....but the work just keeps piling up (Pioneer SX1250 in need of full rebuild, Sansui AU-G99X needs work, and want a full recap of my beloved Sony 7065) and the money does not, haha.
 
Like others have stated, it may be your pre-amp; I've heard stories from several friends over the years that bought that combo and felt the pre-amp was lacking.

I'm currently running P-306RS pre to an M-506RS and M-504, and it sounds great. I've had the P-306RS/M-506RS since I bought them new in 1985 and added the M-504 earlier this year, bought from one of my friends I talked about above, when I added a second pair of speakers to my setup.

I play everything from Classical and Jazz to Metal, and it all sounds fine. Give the amp a chance if you can with another pre before thinking about getting rid of it.

Phil
 
So, I'm just wondering why I haven't done this sooner....

Hooked up the preamp part of my venerable Sony STR7065A to the M504. Put Norah Jones in my Playstation (1001) and pressed play...


There it is. Good, easy sound. Rich bass, warm highs.

Pre must just be effed up. Like I said, it says "remanufactured" on the bottom.

I had read, years ago, all these incredible comments regarding that pre. The P304 was as good as this, or better than that.

Do I just have a lemon, or is it just not that good?

Anyway, I'm elated. Until I can get the op-amps replaced, I'm eyeballing a yamaha C-2 on that site.

So much help. Thanks, everyone.
 
When I first got my 504 amp, it came with the p304 pre... That preamp lasted a few weeks, then I sold it... still have the 504. It has spent the majority of the years with me mated to a denon pma 1500 preamp. I too thought the p304 sounded shrill and edgey sounding.
 
onwardjames said:
So, I'm just wondering why I haven't done this sooner....

Hooked up the preamp part of my venerable Sony STR7065A to the M504. Put Norah Jones in my Playstation (1001) and pressed play...


There it is. Good, easy sound. Rich bass, warm highs.

Pre must just be effed up. Like I said, it says "remanufactured" on the bottom.

I had read, years ago, all these incredible comments regarding that pre. The P304 was as good as this, or better than that.

Do I just have a lemon, or is it just not that good?

Anyway, I'm elated. Until I can get the op-amps replaced, I'm eyeballing a yamaha C-2 on that site.

So much help. Thanks, everyone.
Click to expand...

Outstanding! I'm glad it's working as you expect it to now.

Phil
 
240sx4u said:
If you're gonna be playing with opamps, I'd have someone solder in sockets for you.
Click to expand...

A fine idea, but I'd prob go with whatever Cohibajoe recommended

bobinaz said:
When I first got my 504 amp, it came with the p304 pre... That preamp lasted a few weeks, then I sold it... still have the 504. It has spent the majority of the years with me mated to a denon pma 1500 preamp. I too thought the p304 sounded shrill and edgey sounding.
Click to expand...

Good knowing I'm not alone.

Spinning Abbey Road on vinyl with Technics Sl1301 I got for 30 bucks at a yard sale last week, m97xe cart, thru Sony7065A as a pre, into that lovely Green Monster. Pure bliss.

The kicker is, I have a spare 7065 that has amp issues, sitting in my building. I guess it has a new job, at least for the moment.

Cohibajoe, you think you could recreate that magic on mine?
If so, pm me. If not, its cool.

I wonder what I could get for under 300 for a pre that would really mate well?? The Sony sounds good, but its 40 years old, and I hear limitations (tho the 'color' is there, no dead sounding notes)
 
Thanks, Phil60.

Honestly, can't believe I didn't try a different pre for all these years. I got a pile of gear with pre ability. Yamaha CA810, the Sony, 9090db Sansui, Pioneer sx1250 (be a big ass pre, tho, haha)etc...
 
Buddy brought an M508 and M504 to me after he managed to blow them both up.

I didn't hear them before.

The main filter caps had vented on both.

I recapped the mains on the M508 and she was good.
I recapped the mains on the M504 and rebuilt the front end of them amp around the voltage divider, it was toasted.

Sounded good after that.

IIRC, we stepped up to 10000uf, 100v caps.
Some major surgery and knitting to fit them in (the originals are 4 post with 3/4 posts connected to traces, the traces don'ts connect. :gigglemad:).

Some major soldering involved too. Lots of copper plates. I had to customize new connections.

Flip the M504 over and pull the bottom off.
Look at the bottom of the main 8 caps.
There is a vent hole in the middle.
Do you see goo?

Outside of the caps puking. My money is on a lame pre-amp.
The only "good" vintage pre-amps I know (tried them) are either rare or spendy or both. But I haven't gone through a lot of pre-amps.
 
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