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Otari MX-5050 Review (Reel to Reel Tape Deck)

amirm

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Needed a change of pace so decided to go after a project I planned almost five years ago, namely measuring my Otari MX-5050 BIII-2 Reel to Reel take deck! Otari was the last company in the world making Reel to Reel tape recorders and sadly, ceased production a few years ago. I got my sample from the Reel to Reel master, Ki Choi. I think it cost something like $5,000 to $6,000 new. Used ones go from a range of prices from $2K to $4K from what I see. As always, it is a risky thing to buy one online as conditions of these decks is all over the place and service is not cheap. Mine is extremely clean and as the sub-model indicates, is a more recently sample

Here is a shot of the beast as best as I could fit it in my lightbox:

Otari MX-5050 MKII Review Reel to Reel Tape Recorder.jpg


What makes this model unique and valuable among tape heads these days is that it comes with both NAB and IEC equalization. The latter is what is used for a lot of tape production today (what little of it there is). A lot of consumer decks don't support it and require a hack or outboard equalization/amplifier. The fancy red spool is aftermarket which I bought at an audio show. Costs a couple hundred dollars just for that! Blank tapes are $60 from what I recall. And pre-recorded ones like the one on it are $290 but go way up to something like $600. Each! For some 30 minutes of music as these are recorded at 15 inches/second. So not a practical format for most people. But for those of us who wished we had such a nice unit when young and poor, it brings bag fond memories and good listening as you watch the spools turn and meters dance.

Being rather old, there is hardly an measurements of them by today's standards. There is also chicken and egg problem of how to get an accurate test tape. The de-factor ruler in that world is MRL and that is the tape I used for my testing. It has just a set of test tones and it too is very expensive. How good it is, I don't know. The measurements in the box come from a chart recorder! Let's say it is a few generations behind my Audio Precision analyzer. :)

Otari MX-5050III-2 Measurements
1 kHz tone has been the standard forever in audio and hence it naturally came on the MRL tape so I used it to run our usual dashboard:

Otari MX-5050 MKII Measurements Reel to Reel Tape Recorder.png


Distortion is at -57 dB or so but add a bunch of them and some noise and we land at SINAD of 46 dB. It is strange to see the elevated low frequency noise. Subtracting FFT measurement gain gives us a noise floor that is in the 40s! I wanted to see how much of it was the tape format and how much was the machine so I stopped the playback and measured the noise out of the unit:

Otari MX-5050 MKII Measurements Noise floor spectrum Reel to Reel Tape Recorder.png


Yuck. There is that rising low frequency noise floor but also a bunch of solid tones. What on earth is the 1 kHz and its harmonics coming from? No wonder folks get outboard electronics for these decks (although who knows how good they are).

BTW, the convention for measuring these older electronics is a-weighting so I thought I turn on that filter and see if SINAD gets better:

Otari MX-5050 MKII Measurements a-weighted Reel to Reel Tape Recorder.png


It goes up 3 dB so that low frequency noise is hurting it some. BTW, this is why I don't use a-weighting in my measurements. It really hides a lot of sins in equipment performance at lower frequencies.

There are skirts around the main tone if you look carefully which indicates jitter/speed variations. Watching the dashboard in real time showed a ton of variations. It is a jarring experience coming from today's systems. At 20 kHz, I measured 19.8 kHz frequency so we have about a 1% speed error.

There is not a whole lot more on the tape than a set of fixed frequencies to measure frequency response. My old Audio Precision analyzer could run a sweep against external sources like this by detecting the frequency and then plotting its level. The new APx555 I have now can't do that. It expect you to record its own sequence on the unit and play that to get asynchronous measurements. So I had to resort to the real-time recorder to plot the frequency on the right, and level on the left:

Otari MX-5050 MKII Measurements Frequency Response Reel to Reel Tape Recorder.png


The first frequency is 32 Hz and highest is 19.8 kHz. I set reference at 1 kHz to 0 dB. We see a bass boost at 32 Hz by 1.6 dB or so. And a massive droop at 16 and 20 kHz. Not sure if this is a fault of this unit or in general. It might be this unit as the other channel took a nose dive above 1 kHz! I had cleaned the heads and could see nothing obvious that could cause this externally. Worse yet, I don't know if the tape is bad this way (I assume not but it is possible). I loaned out my last blank tape so need to buy another to record and playback and see how that behaves.

Conclusions
I sort of assumed SINAD would land in 40s and it did. I didn't expect the rest of the garbage this deck produces, nor the one bad channel. Need to find the time to tear it open and see what could be done to improve it. I have not listened to it in months. When I did, my favorite second generation master tape from rock music of 1970s is superb. It easily outperforms the digital ones which have been remastered to death. It is eye and ear popping how much nicer they sound than digital. I often play that tape when people come over first and their jaw drops on the floor in how good it sounds. Tape hiss is there during gaps between tracks and the highs sound a bit distorted to me but neither takes away from enjoyment of that tape. It makes me grin thinking about it as I type this!

Tape gives me the experience of the analog recording without loudness wars and remastering without the limitations and aggravation of LP. I also find the format so much more gorgeous to look at as it plays than anything out there, digital or analog. It is a shame that its popularity has pushed the price of used decks so high.

Anyway, we have first super hard set of measurements of any tape deck now. Gives us some anchoring as far as objective results are concerned.

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respice finem

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Those were the days... I've had two reel-to-reels back in the 80s, not as fancy, but then it was "Polish high end".
Even soldered together a dbx compander, which worked well.
The main problem back then was to get a decent head, the built-in ones didn't last too long, and had audible crosstalk.
 

KEFCarver

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Thanks for the review of your reel to reel deck- a bit of a change of pace! It would be interesting to see how well it would record and then playback a few tones from the AP if you ever get a blank tape. Hopefully you will find the time to delve into the unit some more.
 

DavidMcRoy

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That‘s one of the many decks I used in radio and TV broadcasting for decades before digital audio workstations (DAWs) and digital servers made them obsolete. I seem to remember S/N being around 60dB, though. I also used Revox (budget Studer,) Sony Professional, MCI, Ampex, Scully and others.
 

Tks

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Lets give a round of applause for Amir getting the courage to test his own gear! Even though he says he doesn't because he's worried he'll fry his amps, or that they're too heavy to get setup up :p

Next up, the amps :D

Btw, this image and the tap deck itself looks great. Looks better than the stuff that's able to fit in the light box. Maybe the light is too bright in the lightbox normally? The drop shadow looks perfect.
 

da Choge

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Geez, I guess I'm staying up too late, just like you, Amir (2nd? [well, 5th by now] post to this thread)?

Loved your look back at one of these gorgeous pro-quality tape decks. My Dad bought a nice (well, what I thought was nice at the time) reel-to-reel Sony consumer tape deck in my very young years and us kids had a great time with it (as usual, we all hated how our voices sounded). Then, one day in my late teens, he came home with a pro Ampex tape deck from work (don't know why they had it at his work - he was a Chemical Engineer) -- but I couldn't believe the transformation in sound. This was no audiophile trick to my ears; it was truly transformative in its clarity and accuracy compared to the crap (sorry) we got out of that Sony. I had my own budding turntable-based beginner "audiophile" rig in those days and I didn't think I could ever come close to what that Ampex source was giving me. Haven't really had much experience with tape decks since, but that Ampex made a lasting impression on me.

I don't know what it is, but there seems to be something "magical" about pro-quality tape decks and recordings. Thanks for this audio nostalgia. And, yes, certain people spend great gobs of money to get these today, and then have to shell out $500.00 per recording to hear music through them - amazing!
 
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musicforcities

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That scene from pulp fiction with the reel to reel flashed in my minds eye ! Very cool to see occasional tests of “vintage” (or…obsolete…) gear. Even if the measurements present a puzzle and chuckle.

After all, like a turntable, the pleasure of using these old things derive from the ceremonial set up, the tactility and visuals aesthetics, as well as their sonic qualities ( not always including transparency).

I appreciated fir the same reason your review of the Douk VU meter/ switcher (too bad it was rubbish). I have an irrational attraction to old amps with giant meters and acres of thick stainless steel. Like the Luxman m4000. Any decent ncore based amp would likely run circles around it even at its original 120wpc at 108db s/n 0.05%THD for 1/10th the energy use and 1/20th the mass. But that Luxman would be great next to this reel to reel!

137F17C9-1775-442D-A6F4-408FCB6701BD.jpeg
 
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restorer-john

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@amirm what about a record to replay THD test using the AP's low distortion generator as the source? You have a blank tape (or a bit at the end unused)?

We really have no idea how much of the THD is on the test tape and how much the machine is producing. What level was the 1kHz test done at as the machine is only putting out ~1V. Was the output level pulled back?
 

GXAlan

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Imagine you are walking on a beach. You stumble across an old box of Kodak film. Turns out that there are two boxes.

The first, is a pristine sample with the classic gold and red colors, except there is a sprinkling of sand over it.

The second is a sun-faded sample where the gold and red colors aren’t as intense as they should be, but there isn’t even a single grain of sand on it.

When you measure the “average” color the presence of the sand will lighten and dilute the underlying color. The two boxes may quantify similarly.

But I believe that I would prefer the true gold and red colors with noise over the clean, faded one.

This analogy can be applied to the mixing/mastering.
 

musicforcities

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on
@amirm what about a record to replay THD test using the AP's low distortion generator as the source? You have a blank tape (or a bit at the end unused)?

We really have no idea how much of the THD is on the test tape and how much the machine is producing. What level was the 1kHz test done at as the machine is only putting out ~1V. Was the output level pulled back?
one would need good tape I suppose. I don’t know about reel to reel, but i hear from the cassette deck fetish crowd that even NOS (new old stock) cassettes are often way out of spec due to age.

Hmmm I wonder how those old mid 90s Zip drive disks I have somewhere filled with aac lossless cd rips are holding up…lol.
 
OP
amirm

amirm

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@amirm what about a record to replay THD test using the AP's low distortion generator as the source?
I had a spool of SM900 but loaned it out to a friend (and got his MRL tape I used in this review as exchange). Went to buy a new one just now and price has gone up from $60 to $90!!! :eek:
 

DualTriode

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Worth every dime.
I want to hear more. Dig in.

Thanks DT
 

restorer-john

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Went to buy a new one just now and price has gone up from $60 to $90!!!

Ouch!

Pulled out an Akai GX-625 recently to play with, but I'm not paying hundreds of dollars for blank tape when I have some. I have 4 Emtec/BASF SM (Studio Master) 468 NOS someplace in my storeroom and I can't find them. In a box with other 10.5" NAB reels, demags and splicing tape goodness knows where. :facepalm:

This model (internet pic)
1632722999452.png
 

restorer-john

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How is it possible with that data, please ?

Good open reel sounds fabulous. Just puts a smile on your face with its warm, fat sound. You can't turn it off- that is until the tape runs out... ;)
 

laudio

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Those measurements are god awful ugly. But it's a nice looking set of gear so much better than what we get now.

I have cassettes (not RTR) that I recorded almost 40 years ago when I did it that what I like to call "air and presence" to them (with a ton of hiss of course) and sound better to me than digital streaming. Most likely CD rips when I borrowed on a cheapy tape deck and it sounded good with whatever hot bias trick I was using at the time. They were "mastered" to sound good.

I still like them. Can't explain it in this day and age - they sound good to this day because I did it. That's all that matters. Nice review. Just shows that measurements are not everything.
 
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phoenixdogfan

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Wow, brings back memories. Used it to create tapes of LPs. Unfortunately, a young 19 yo didn't have access to studio master tapes in the early '70s.
 
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