Marantz 16 80W - What to do?

[Jose Jimenez]

Helllo!

I have a Marantz Model 16 amplifier that looks like new, sounds like crap. Not a hint that it derived from the very listenable Model 15's. I figure the operational amps have something to do with this sonic presentation. Has anyone tried to change these for newer op-amps or done other modifications worth noting?

I really would appreciate the information. Jose

[Bone]

How does it sound like crap. Is it too bright, too dark, distorted or what?

[Jose Jimenez]

Total lack of detail. Sounded like a mp3 file. Also no low bass. It reminded me of some of output capacitor coupled amplifiers around 12-15 Watts in the 70's. I inserted some other amplifiers back into the system and my toes and fingers were tapping and snapping! You could not be involved with that amplifier at all.

[sgrossklass]

Got a link for a schematic?

EDIT:
No low bass probably means some dead 'lytics, either coupling caps or feedback. Even if it sucks, it should have bass. Probably hasn't had service since it was built. Idle current may well be off, too.

OK, so here's a Usenet post I found:

[...] As I recall it was 2 small
monoblocks bolted together to a single front panel. Very tight inside. Full
complementary outputs, with a first generation op amp IC at the front end.
Sounded awful. Filter caps were prone to failure and it wasn't very good
into low impedances. The OP is right. Not one of their better efforts.

Uh-oh. First-generation opamp, that could be a µA709 or somesuch. Thoroughly antiquated. That, in theory, would be replaceable with some creativity.
Not very good into low impedances - sounds like the output stage sucks, too. All in all, I bet the affair has some serious high-frequency (crossover) distortion.

I'd say pass it along to a collector who prefers looking at it. Any mods to improve its performance would be quite advanced stuff, and people typically aren't too keen on devices that have been tampered with save for repairs.

[Notanotherbox]

go to eserviceinfo.com

[Notanotherbox]

I don't have the schematic in front of me but the operational amplifiers used where slow as compared to a 741. No harmonic accuracy?

[Notanotherbox]

I have a note written down here and the op-amps are LM201AN's. I was looking at the specs for TL071, NE5572, LM74, NE5534An, etc.

I have a number of Marants Model 15's that is very similar after the differential amplifier and they all sound wonderful being period correct. Yes there are better but they amaze me how well they sound. The 15 uses a single pair of outputs, the 16 had two pairs. No big deal here.

I'd like to chat more...