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
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
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.
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:
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.
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:
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.
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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...
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...
Hi,
Sorry to drag up an old post, but I've got a model 16 and I found the thread. I downloaded the service manual from the guys referenced above, and wow, I'm amazed the thing even works. The early units had LH201 op amps and later ones had LM201 op amps. It would be possible, but probably not practical to upgrade the op amps. The LM201's were really fast, uncompensated early op amps. Besides the compensation on the op amps, there's a type 3 compensator on the feedback from the output. That will get maximum bandwidth possible for the amplifier. They probably had to measure the Bode plots by hand with an HP gain/phase meter. What a nightmare.
The thin lame sound will be from capacitors, not op amps. Recapping would be a huge hassle in the cramped insides of these things, but would probably be rewarding.
Mine has decent bass and sounds pretty good. The input common mode rejection is terrible though and my tube line stage hums like crazy through it. For an amplifier made in 1969, 100 watts out is amazing. I'll bet they were typically teamed up with JBL L100's which were rated at 100 watts too. I've got them on JBL 4311B's.
Marshall
Sorry to drag up an old post, but I've got a model 16 and I found the thread. I downloaded the service manual from the guys referenced above, and wow, I'm amazed the thing even works. The early units had LH201 op amps and later ones had LM201 op amps. It would be possible, but probably not practical to upgrade the op amps. The LM201's were really fast, uncompensated early op amps. Besides the compensation on the op amps, there's a type 3 compensator on the feedback from the output. That will get maximum bandwidth possible for the amplifier. They probably had to measure the Bode plots by hand with an HP gain/phase meter. What a nightmare.
The thin lame sound will be from capacitors, not op amps. Recapping would be a huge hassle in the cramped insides of these things, but would probably be rewarding.
Mine has decent bass and sounds pretty good. The input common mode rejection is terrible though and my tube line stage hums like crazy through it. For an amplifier made in 1969, 100 watts out is amazing. I'll bet they were typically teamed up with JBL L100's which were rated at 100 watts too. I've got them on JBL 4311B's.
Marshall
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