2275 mods for better sound?

[ssouci]

I'm assembling the parts needed to re-cap my 2275

have heard rumors of some "part swaps" that can significantly improve the sound quality in a 2275 vs. the stock configuration (foil caps, special resistors, etc.)

seems like a great opportunity to get better sound just by swapping out some parts -- seeing as I will already have my unit apart and will be re-soldering every joint anyway

can anyone make some specific upgrade recommendations?

(with some regard to cost, as my budget is limited...)

would be greatly appreciated, thanks!

 

[airtime]

I would stick with the same circuits. If you change anything:

use audio grade electrolytics in the audio path.

consider using some WIMA film polypropylene coupling caps - bit this is clearly not a deal breaker!!!

if there are any of those 1/4 watt resistors in the audio path move on up to 1/2 radioshack carbon films of equal value. Again nice but not a deal breaker

Otherwise recap it from front to back, make sure it's up to spec and maybe LED the lights and enjoy!!!!

charles

 

[ssouci]

Airtime: thanks very much for the reply

yup, I'm doing full recap and resolder of PCBs, plus LED lamps

when you say: "use audio grade electrolytics in the audio path.... use audio grade electrolytics in the audio path... 1/4 watt resistors in the audio path... etc."

what exactly constitutes the audio path? the tone board only?

I'm not wanting to alter the great Marantz circuitry in any way, but rather just looking for straightforward "part swap" upgrades (eg. same value but a better-sounding component)... seems like a lost opportunity NOT to do it while I'm working on the boards

if you or anyone can suggest some part swap upgrades for a 2275 with specific component #s or locations, that would be ideal of course, since I don't really feel qualified to start deciding upon these specifics on my own

PS: I do have the service manual so can see the various PCB layouts and parts list

thx!

 

[PacificStereo]

If you simply recap that puppy with FC-series electrolytics, you just will not believe how much better it sounds. Yeah, perhaps a few special caps here and there if you really feel up to it, but the FCs are incredibly good.

 

[airtime]

Basically you will not be "changing" the sound if you replace a film with a film cap and an electrolytic with an eletrolytic. You can altering the sound if you start replacing polar caps in the signal path with film caps. From years of doing that I personally DON'T recommend it. No matter what the stereo guru gods may say. That amp was voiced to work at peak efficiency with what's in it.


The audio grade caps are usually Nichicon FW or KW series. If you use these on the amp and preamp boards you'll be fine. I'll see if I can post the flow chart from Nichicon.

http://www.audiokarma.org/forums/attachment.php?attachmentid=194037&d=1265566325
charles

 

[stahlhart]

Film capacitor bypass on the power supply filter?

 

[Markw]

Many people seem to think that change = improvement.

As has been stated, you may change the sound but not all changes are an improvement.

Now, if you have a specific goal in mind, well...

 

[ssouci]

thanks everyone!

I'm going with the FC caps all around, a few replacement transistors (phono + amp boards), and bypass caps across the 2 large cans

 

[airtime]

I would only replace transistors that are no longer any good. Don't start fixing working parts or you will get more than you bargained for. Electrolytic caps do age and degrade. Not much else in there does.

charles

 

[PacificStereo]

Yeah, I would be careful about replacing perfectly good semis. There's really no reason to do it unless you have (or suspect) a problem, or to fix a problem that is known to develop (like leaky 2SC458s, for example).

Airtime, I was unaware that Gromit was into that sort of thing!

 

[Markw]

A wise man once told me that when doing a rebuild, do a few parts at a time and play the unit. It's easier to go back a few steps to correct a "new" problem" rather than to have done the whole thing and then try to figure out where it went wrong.

That man is a well-respected tech in this area.