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

[sarumbear]

Regarding digitising old recordings. I was told in the 90's by people who worked with said tapes that it was a race against time as many tapes from the 60's onewards were beginning to shed - and this is before the Ampex (and others) thing about tapes needing to be baked first before the one safe playing to digitise them...

That is known as the "Sticky-shed syndrome". The deterioration of the tape was caused due to the breakdown in the binder, which sticks the oxide particles on the tape. EMI tape that we used used a non hygroscopic binder unlike the Ampex & Scotch brands used in the US, which used an unstable binder. This is why The Beatles and later Pink Floyd masters are still in pristine condition.

By the time US and later Japanese manufacturers started manufacturing tape in mass for cassettes they were aware of the issue and stopped using unstable binders. This is why cassette tapes last longer than most master tapes in circulation.

 

[rj45]

Back in the mid-80s, I worked in a professional music studio - this was just before the first digital tape recorders.
So yeah, we used Ampex 440B two track decks to master.
Both Dolby and DBX noise reduction outboard units improved S/N by a huge amount.
But I sure didn't expect a .5% THD from the Otari. Yikes!

I got a Teac 2340 RTR about 20 years ago on Ebay for $100. Just had a stuck brake, then it worked perfectly!

 

[001]

Very enjoyable thread. Thank you all. Last century I was given a lowly Sony reel to reel as a teenager by an uncle. Teamed with an even cheaper FM tuner that would tune below standard Australian frequencies, I spent many late nights recording what I think were police comms in Melbourne on quite a few reels.
I thought it the height of excitement. I've no idea if this was legal.

 

[AndreaT]

It is a bit of a puzzle: poor distortion, lots of noise, lots of wow&flutter: why does it sound so good? Are we still missing some other measurements that might shed some light on this paradox?

 

[sergeauckland]

It is a bit of a puzzle: poor distortion, lots of noise, lots of wow&flutter: why does it sound so good? Are we still missing some other measurements that might shed some light on this paradox?

My view is that it's because all those 'poor' measurements are actually Good Enough for it to sound OK. It's as good as or perhaps even better than the tape machines that made many classic rock/pop and jazz recordings in the 1950s and 60s.
0.5% distortion and a +-3dB frequency response to 19kHz are both audibly fine. I didn't see any W&F figures, but would be surprised if they were worse than 0.1%, so again OK. Noise was a bit high, but what's that relative to, I don't know so may be fine relative to a fully modulated tape.

We don't need >-90dB SINADs for something to sound good, or frequency responses flat to -1dB @ 100kHz. We have them these days as it's hard not to and it is indicative of good design, but not necessary.

S.

 

[audio2design]

That seems like a ridiculous claim. I believe there's more to analog recoding than can be defined using a number of bits.

No not really except for the soft compression as the tape saturated. That can be simulated in digital.

 

[sarumbear]

Yes but that was at 3% total harmonic distortion!

Where do you see that value? @amirm measures -57dB which is around 0.14%. He hasn’t told at what level that was measured, but his figure is not much worse than a Studer. You have to remember that SINAD is a combined figure of distortion and noise. On an inherently noisy medium like tape, SINAD is not a good measure for comparing to modern devices where noise is often negligible.

 

[audio2design]

It is a bit of a puzzle: poor distortion, lots of noise, lots of wow&flutter: why does it sound so good? Are we still missing some other measurements that might shed some light on this paradox?

It sounds good, not "so good". The compression of saturation is a pleasing effect which can enhance low level detail by allowing effectively louder playback.


That and as noted, if you do hear one it is likely a top notch recording with little processing.

 

[sarumbear]

It sounds good, not "so good". The compression of saturation is a pleasing effect which can enhance low level detail by allowing effectively louder playback.

That and as noted, if you do hear one it is likely a top notch recording with little processing.

If you haven’t yet, listen Harry Belafonte Live at Carnegie Hall recorded in 1959 direct to 2-track tape. Neither Dolby nor multi-track tape was yet invented. Irrespective of their music taste no audiophile can argue with quality of the music and the effect of being there. Those recording engineers were alchemists. They retired and their knowledge had died.

 

[DSJR]

I seem to remember that 15IPS masters (1/4"?) offered something like 18dB over then accepted '0dB' which was often used as a gentle compressor. I apologise for not having precise figures (nWb/m I think the measurement was). This was used a lot in excess by some pop producers to give a good 'punch' to singles (that and a Fairchild-style compressor no doubt ).

Little tale - Decca Solti Mahler 6 from the 60's. The ending is full-on and 'distorted' so i put it down to mistracking on the MC cartridges which had come back into fashion in the later 70's. Thing is, the CD issue sounded the same, so put it down to tape saturation. My mastering engineer pal got the original tapes out of the archives (I think it was for work rather than pleasure here) and did some listening and measurement on his workstation. Turns out it was phase distortion in the recording session itself! Doesn't get in the way of the musical qualities though Bloody good job I never got a job in the recording industry, as I'd either have been sacked for wasting musician and producer's (expensive) time, or I'd have been sweeping the studio floor or similar!

 

[DSJR]

If you haven’t yet, listen Harry Belafonte Live at Carnegie Hall recorded in 1959 direct to 2-track tape. Neither Dolby nor multi-track tape was yet invented. Irrespective of their music taste no audiophile can argue with quality of the music and the effect of being there. Those recording engineers were alchemists. They retired and their knowledge had died.

You'd know far more, but I gather 30IPS and half inch two track tape is very quiet indeed and doesn't really need add-on noise reduction. My only reference for this is the first album by 'The Blue Nile' (Walk Across the Rooftops) which I heard and had a test acetate cut of most of a couple of tracks in front of me from an ATR 102 (which seems good for playback on a review I read not long ago). Also confirmed by the late Adrian Kerridge in his book - Boy, did they abuse the tape saturation available to get the effects they wanted...

"Tape's Rolling, Take One": The Recording life of Adrian Kerridge: Six Decades of Recording and Producing, from the Rock ‘n’ Roll Years to TV Scores & Blockbuster Movies!: Amazon.co.uk: Kerridge, Adrian: 9781911124221: Books

Buy "Tape's Rolling, Take One": The Recording life of Adrian Kerridge: Six Decades of Recording and Producing, from the Rock ‘n’ Roll Years to TV Scores & Blockbuster Movies! by Kerridge, Adrian (ISBN: 9781911124221) from Amazon's Book Store. Everyday low prices and free delivery on eligible orders.

www.amazon.co.uk

 

[sarumbear]

Turns out it was phase distortion in the recording session itself!

What is a phase distortion and what causes it?

 

[sarumbear]

You'd know far more, but I gather 30IPS and half inch two track tape is very quiet indeed and doesn't really need add-on noise reduction.

Possibly but by the time 1/2” 2-track machines have arrived we were using 2” 16-track which was noisy, hence needed Dolby.

 

[MakeMineVinyl]

Where do you see that value? @amirm measures -57dB which is around 0.14%. He hasn’t told at what level that was measured, but his figure is not much worse than a Studer. You have to remember that SINAD is a combined figure of distortion and noise. On an inherently noisy medium like tape, SINAD is not a good measure for comparing to modern devices where noise is often negligible.

The 3% distortion level was the standard used by Ampex (and probably others) for establishing 'maximum recording level', and that level was used as the reference point for determining signal to noise ratio. This level was typically 6dB above the level which was used as the standard operating level - that level was 185nWb/m in earlier years, and 'modern' tape formulations are classified as +3, +6 or +9 dB above this level.

The typical distortion level at operating level is 0.6% and is almost entirely composed of odd-order harmonics (the magnetic recording process cancels even order harmonic distortion). Somewhat disingenuously, distortion was stated in professional specifications as "x% 2nd harmonic distortion at 400Hz" - well, that's rich, considering the 2nd order distortion would normally be totally absent. That, and the 'fudging' of signal to noise specification by using maximum recording level shows that marketing was alive and well, even in professional circles back in the day.

 

[MakeMineVinyl]

But I sure didn't expect a .5% THD from the Otari. Yikes!

Why not - that's typical and this is limited by the tape, not the machine.

 

[sarumbear]

The 3% distortion level was the standard used by Ampex (and probably others) for establishing 'maximum recording level', and that level was used as the reference point for determining signal to noise ratio. This level was typically 6dB above the level which was used as the standard operating level - that level was 185nWb/m in earlier years, and 'modern' tape formulations are classified as +3, +6 or +9 dB above this level.

The typical distortion level at operating level is 0.6%.

What you are saying is not reflected on the ATR spec sheet. At 6dB above the operating level distortion was less than 0.1%. Where do you get your figure which is 30 times higher?

 

[sarumbear]

Why not - that's typical and this is limited by the tape, not the machine.

@amirm’s measurement of the electronics alone shows 0.4% distortion. Tape is not adding too much distortion.

 

[MakeMineVinyl]

@amirm’s measurement of the electronics alone shows 0.4% distortion. Tape is not adding too much distortion.

That sounds like a problem with the machine's electronics. It was not difficult to achieve better distortion levels in electronics of the period. The fact remains that in good, professional machines, the tape was the major contributor of distortion. I'd be curious to see an FFT of the complete record-playback distortion at a specified operating level. Just playing back a properly recorded tape of 1kHz, all one should see is odd-order harmonic distortion. If there is even order distortion present, it is not coming from the tape itself unless that tape had problems upstream.

Typically the presence of even order distortion means that the heads might be magnetized, or that there is a leaky coupling capacitor (when used) on the output of the constant current amplifier driving the recording head, or just simply something wrong with the electronics elsewhere.

 

[sarumbear]

That sounds like a problem with the machine's electronics.

Yes if you read the review you would see that there was.

 

[DSJR]

What is a phase distortion and what causes it?

The Decca Tree mic system I believe. Said pal had a 'scope' type display in his room which showed it I believe and it wasn't azimuth errors either. Long time back now that we discussed it, but we both heard the distortion on the vinyl and it went on from there as the CD appeared and he was then in a position to investigate further 'from the horses mouth' as it were and with the actual analogue masters used. (He was also able to see the slight? increasing errors on a well played digital master after repeated playing although back then, they were correctable). These days I believe it's much simpler and the engineer who stayed on in the premises after Polygram as-was fully absorbed the archive into an off-site location and th ebuilding reverted into mixed office facilities, changed to a commercially available workstation I seem to remember from an article I read years ago.