[bundee1]

I just got an onkyo a9555 and the mids are a little recessed and it lacks drive. The soundstage is huge but diffuse. A guy named bobwire on audioasylum modded his but didn't post pics.

I have a little experience with soldering and modding but I don't think I can do surface mount components. Any help would be greatly appreciated.

Anyone work on one of these? It has a lot of potential and I like the efficiency of digital amps.

[Ethan Winer]

The soundstage is huge but diffuse.

I would be remiss if I didn't point out that this is 100 percent a room acoustic issue, totally apart from the gear.

--Ethan

[Occam]

When your only tool is a hammer, one does tend to percieve everything as a nail.....

[bundee1]

I need real help, not vague comments please. I don't have any other rooms to put it in so I guess I'll have to live with the soundstage. My last digital amp had tighter bass, better rhythm and better imaging but it lacked power. Can anyone really help me with the attack and bass problem?

[JoshK]

I wouldn't expect much help without a schematic.

[Occam]

Bundee - My previous comment was directed at Ethan, not you....

Bobwire made 2 posts about modding your Onkyo
http://db.audioasylum.com/cgi/m.mpl?forum=tweaks&n=151071
http://db.audioasylum.com/cgi/m.mpl?forum=tweaks&n=151885

In both posts he mentioned he has pictures of the mods and would send them to folks who contacted him. Use AA's email facility and ask.

Bob mentioned the specific parts he replaced, by part #. If the part #s are not on the amplifier board itself it will be on the schematic in the service manual which you might be able to purchase from Onkyo.

[bundee1]

thanks and sorry about the misunderstanding occam. I found only one of bobwires posts and it does lists the parts to change, but I dont want to disable the phono stage. Ive contacted him for pictures but he hasnt responded. Thanks for the help and support guys.

[Ethan Winer]

I don't have any other rooms to put it in so I guess I'll have to live with the soundstage.

Even a couple of large bath towels folded over to be twice as thick, placed at the side-wall reflection points, will make a very large improvement in imaging. This may not be an acceptable permanent solution, but it's certainly useful to try as an experiment.

--Ethan

[bundee1]

Thanks for the suggestion. I know the room is a problem but my other amps were much better at imaging, so the room is only partly responsible and a much smaller part than you think. 

[bundee1]

"The first thing I did was to remove the IC?s from the tone control PCB and put in sockets. The IC?s were up-graded to LM4562?s. I first tried some OPA2132?s that I had on hand. They worked but showed there color. The 4562?s are much better in every way.
There are also eight capacitors to change on that PCB. The six 47uF coupling caps and were changed out for 220uF. Next, the two 470uF power filter caps were changed out for 2200uF/16V caps. There are two 33ohm resistors that I shorted with jumpers. This ties the caps closer to the power supply for more impact.
I don?t use the phono stage but decide to make use of it to help out the power supply rails. First, I jumpered out R?s 151, 152, 153, and 154 (33ohm) and then I changed out C?s 109, 110, 125, 126, 127, and 128 for 1000uF units.
On the main PCB there are 100pF caps at all input and output jacks. These are little red poly-prop caps. I clipped all of these right off the PCB, removing them all. They only dull the high end. These caps are numbered C201 to C216.
Last and most important, are the two pair of caps on the main PCB. These are C345-C346 and C975-C976. I could not un-solder them without taking the whole amp apart so, I clipped them off as CLOSE TO THE BODY as I could. This left me a little stub that I could solder the new cap leads to. It was very tight in there, so take great care not to melt anything else near by."

Can anyone recommend replacement caps and a place to buy them based on the changes recommended above

[BillB]

Panasonic makes highly regarded caps. I actually have about 50 of the 2200uf 16v caps.