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Marantz PM-90 Review (Vintage Amplifier)
- Thread starter amirm
- Start date
@restorer-john do you have a service manual for this PM-90? I can't find one without giving my credit card info to some weird looking web site. I'm curious about that power supply arrangement with the dual transformers. Perhaps they use the transformer secondarys like that Denon amp we looked at ~month ago.
That is truly a classic visual and functional design that will never look dated, and a beautiful non-black finish. I wish manufacturers competed more on looks - I think it’s a big factor in purchasing.
Out of curiosity, who was Marantz' parent company at time of this amp's manufacture?
MakeMineVinyl
Major Contributor
I was also going to mention that it is not a good idea to run a component designed for 100V on 120V, but you beat me to it, and for all the same reasons I would have given.
Philips. This was 1991 and the very last amp BEFORE they started adding HDAM.
Thank you.
KEFCarver
Active Member
Like the review of Older Gear like this! It looks like you used the same signal levels for testing both the MM and MC- wouldn't the MC be less..?
Question for the technical experts here including @amirm since he brought up the "pattern" of distortion. If you cut off the distortion at -110dB and compare it to 3 other "interesting" amps tested here, it seems like the Marantz PM-90 has lower 1st and 2nd order distortion.
If you cut off the graph at -100dB, there is no distortion at all on PM-90, but on the other 3, which have lower overall THD, you actually have distortion above -100dB.
1) What does this mean if you're playing a source <100dB in dynamic range?
2) Would potentially cleaner AC power translate into better measured performance in this particular case where there are high AC harmonics?
If you cut off the graph at -100dB, there is no distortion at all on PM-90, but on the other 3, which have lower overall THD, you actually have distortion above -100dB.
1) What does this mean if you're playing a source <100dB in dynamic range?
2) Would potentially cleaner AC power translate into better measured performance in this particular case where there are high AC harmonics?
Upper left: Marantz PM-90, Upper right: Schiit Aegir, Lower Left: PS Audio M700, Lower Right: Accuphase E270
restorer-john
Grand Contributor
I've got it somplace in a printed version, but not easily accessible. The block diagram for the PSU is in the link above. I've got the PM-95 S/M (printed), but it is completely different is every respect, although they were both built on the same chassis and have somewhat similar looks.
restorer-john
Grand Contributor
One more question.
Here are two amps. The right one is mirrored, so you can look at 20W and down for easy comparison.
If I'm looking at the colors correctly, 500Hz is the top most which suggests that the amplifier on the right is worse in the 500 Hz range up to about 20W, even though the 1 kHz and 5kHz are clean?
Left is Marantz PM-90
Here are two amps. The right one is mirrored, so you can look at 20W and down for easy comparison.
If I'm looking at the colors correctly, 500Hz is the top most which suggests that the amplifier on the right is worse in the 500 Hz range up to about 20W, even though the 1 kHz and 5kHz are clean?
Left is Marantz PM-90
One of the Hypex NC252MP tested here.
OP
- Thread Starter
- #36
It is. I use 5 mv for MM and 0.5 mv for MC. The dashboard is showing the output, not input.
seaninbrisbane
Member
Very nice - particularly as it has the ability to work with three tape decks!
It's a neat unit. I especially like how there is a minimum of circuitry. The amp PCB are populated with a minimum of components and the rest of the unit is the same.
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