Denon DR-M20 Preliminary Measurements
I'm posting these quick measurements in case anyone is looking for an affordable, no-nonsense vintage tape deck that performs very well. This is a high quality 3-head Denon cassette deck from 1986 that goes for a lot less than better known Denon decks such as the DN-790R and even the DR-M22. I think it is a sleeper. It is still possible to get a good deal on these (I got it for $80 last year), but of course you want to be patient in order to get one in good condition. It is on queue for a full refurb so the measurements are of the deck as I got it, which I think is beneficial here. Additional measurements of the recording capabilities will come in the future. Retail was $400 ($1123 today with Covid-era inflation).
Picture from a random eBay listing.
You get Dolby B & C, bias adjustment, and an MPX filter in case you want to record FM broadcasts, lol. Not much, just the important stuff, but the cassette mechanism is high quality and silent as advertised. You should get better performance from these over the dual decks that took over in the 1990s.
Again, I used ABEX test tapes and my E1DA Scaler and Cosmos.
Speed and wow and flutter. I try my best to capture median results as there are slight swings with these. WRMS and weighted quasi peak.
Wow and flutter is superlative and still at spec nearly 40 years later!! (Though clearly use was minimal.) Speed has maintained well but could use the tiniest tweak. You will have to spend A LOT to do better but unless you see measurements its all hypothetical. My Nakamichi is spec'd at 0.04% but this one is there and that one isn't. The belt works perfectly. This is why I can't recommend Sonys unless you can fix them yourself AND have a good belt source. We seem to have come to expect goo and that shouldn't be the case. This is also why I recommend brands such as Realistic, which used high quality belts. You have a better chance of getting something that works close to spec this way and thus they are better options for modern buyers of vintage gear, IMHO.
Distortion measurements based on a 1kHz type I tape.
Again, the tape is limited in usability for noise results. We can see more harmonics than on the Nakamichi. I'd have to open it up to see if there is anything going on but in general these are pretty standard results. Maybe one dB or so less than what I have been averaging. That number could well be measurement error.
1kHz oscope and lissajous (phase).
12.5kHz oscope and lissajous.
The deck needs a bit of azimuth adjustment (super easy if you have a test tape). Let's see if it messes with the FR as is.
It could use some azimuth adjustment. Ironically the one with the left and right channels splintering off in the highs is the CD version. But as you can see the FR is not bad as is. It should be slightly warmer and even pleasing. We will see what happens after adjustment.
Basically this deck has very good bones. If you can find one in good condition, you might get a gem for peanuts.
