Plugging MC into a MM Phono amp

Hello everyone,

I’m using a Heed Quasar phono stage + SuperUniti (SU as preamp) + NAP 250DR. The tt is a modded GL78/audiomods arm(kit)/ Denon DL103r that has worked fine for the most part over the last 3 to 4 years, marred occasionally by hum. I live in an extremely hot and humid, sea salt laden environment, and visible tarnish is impossible to avoid. I’ve always been able to solve these problems using ‘analogue re-boot’, i.e. cleaning contacts, ensuring earth, continuity testing etc.

I’ve run into trouble with this phono part of the system and I think the Quasar + PSU is the offending unit - my question is whether it would be okay to plug the MC turntable/cartridge output to into another ‘MM only’ phono amp just for troubleshooting?


Can you do this safely? Yes.

Will it help troubleshooting? Doubtful. There is an order in magnitude difference in the output of a standard MC compared to MM. As such you are very unlikely to get audible output.

Worth noting the reverse is not true. It is generally not a good idea to connect MM cartridge to a MC phono stage. For the obvious reason that it is expecting a signal 1/10th the voltage and applying gain accordingly.

You could. However, obviously output will be well down, so it may not show you much if anything, and may just further confuse matters.

However, if you’re up for a little bit of online auction action, then you could look for a pair of little inline transformers - these were made by Ortofon (T5), but were also sold with Sony (HA-T10) and Empire badging - which will bring the low output of your Denon MC up to an output suitable for an MM stage. They should only cost you around £40, perform really well, and can be very useful…

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Actually… scratch that! I’ve done a quick search and I must be a bit out of date on my pricing. It wasn’t that long ago you could buy these things for a tenner…

I simply wanted to listen out as to whether some signal was reaching the speakers. I understand the requirement of gain being a couple of orders of magnitude higher for the MC, but is there danger of of an impedance mismatch causing damage to anything? I have a $40 MM phono stage lying around.

For the long. term I’m looking to repair the Quasar, or move towards a suitable NAIM phono stage.

I use a DL103. Used it to check if the phono stages of a few integrated amps are functioning without a problem.

Hi and thank you Richard,

Unfortunately I do not have much of a MM phono stage, it’s a ($30) Behringer, so I might as well go in for repair to my Quasar, or a suitable NAIM phono amp, or, replace my SU with a NAIM pre-amp with internal or external phono stage. (the SU display has faded a long time ago and the local service guys plead inability to fix).

The Quasar MM circuit hasn’t been working for a while now, but the MC circuit has been fine so far, though it maybe shot at the moment, and the logistics of getting it to HEED in Hungary are complex, more so during this pandemic.

BTW I read nice things about the Denon HA-50 MC head amp, but it’s a different price point and makes no sense given lack of a quality MM phono stage.

Exactly what I want to do - so you got a soft but audible sound from the speakers/headphone?

Yes. Quieter and duller, with very little treble if I remember correctly.

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