I purchased my Technics RS-TR333 new in 2004, for $199.
Amazing build quality, still on original belts and playing perfectly.
FYI here is the exact pinch roller washer for the MX-5050 BII at least. Not sure about other models. I successfully ordered 10 from them in 2020 and can confirm they seem identical.
https://us.misumi-ec.com/vona2/detail/221000715783/?HissuCode=PS/W-6.2-9.5-0.25
https://us.misumi-ec.com/vona2/detail/221000715783/?HissuCode=PS/W-6.2-9.5-0.25
It's a Facebook group called Only Otari and is free to join. Sorry for the very late reply, I did not see this until today.
Hello Kevin.
Long time no talk to - hope you and Amy are well. Guess/hope that there may be a Walterfest this summer so we can reconnect!
Saw this post and actually have some MX-5050 "news" to report. Was just down in Brooklyn a few weeks back visiting Rhapsody Audio. 6 years or so ago, the proprietor, Bob Visintanier bought my last Studer A812 (with the repro head wired out to my tape pre) to use in his old Manhattan showroom. Didn't use it much and sold it along with all of the tapes he accrued. Then he moved to new, much larger digs in Brooklyn and wanted to get back into tape. Found a gentleman in that borough who overhauls and maintains a "stock" of prosumer machines, from whom he ended up buying two 5050's. Sent him my remaining Nortronics pro playback heads and he had John French mount them in the headblocks and wire them out. Bought two of my pre's and has the results in two of his three listening rooms. 5050's seem to be very nice transports all tho the restorer said they have more W/F than other machines he is familiar with. Combo sound VERY nice driving various megabuck electronics / speakers. look up the "products" he reps if interested - mostly European - never heard of many of the brands before the trip.
Do agree that the Axxx series decks are VERY lacking in the sonics category - especially after being able to A/B the playback on the 812s I had (stock vs "outboard"). As you know from a perusal of the schematics, Studer "wrapped" digital around the analog circuitry including MANY A/D's to "easily" control signal levels and EQ boost/rolloff. These all take their "sonic toll".
Current project is coming out with a new "plug n play" repro module for the A80 - which also could use some sonic help. Initial listening results (by others) seem quite favorable. A redesign of the Axxx repro card could be in the works but you also then need to upgrade the little fixed-gain preamp in the headblock; so it's no longer a plugnplay installation. So much for retirement
Best and keep up your good work.
Charles
Long time no talk to - hope you and Amy are well. Guess/hope that there may be a Walterfest this summer so we can reconnect!
Saw this post and actually have some MX-5050 "news" to report. Was just down in Brooklyn a few weeks back visiting Rhapsody Audio. 6 years or so ago, the proprietor, Bob Visintanier bought my last Studer A812 (with the repro head wired out to my tape pre) to use in his old Manhattan showroom. Didn't use it much and sold it along with all of the tapes he accrued. Then he moved to new, much larger digs in Brooklyn and wanted to get back into tape. Found a gentleman in that borough who overhauls and maintains a "stock" of prosumer machines, from whom he ended up buying two 5050's. Sent him my remaining Nortronics pro playback heads and he had John French mount them in the headblocks and wire them out. Bought two of my pre's and has the results in two of his three listening rooms. 5050's seem to be very nice transports all tho the restorer said they have more W/F than other machines he is familiar with. Combo sound VERY nice driving various megabuck electronics / speakers. look up the "products" he reps if interested - mostly European - never heard of many of the brands before the trip.
Do agree that the Axxx series decks are VERY lacking in the sonics category - especially after being able to A/B the playback on the 812s I had (stock vs "outboard"). As you know from a perusal of the schematics, Studer "wrapped" digital around the analog circuitry including MANY A/D's to "easily" control signal levels and EQ boost/rolloff. These all take their "sonic toll".
Current project is coming out with a new "plug n play" repro module for the A80 - which also could use some sonic help. Initial listening results (by others) seem quite favorable. A redesign of the Axxx repro card could be in the works but you also then need to upgrade the little fixed-gain preamp in the headblock; so it's no longer a plugnplay installation. So much for retirement
Best and keep up your good work.
Charles
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Hi Charles,
Great to hear from you. I recently purchased a fully restored A810 from Dana, I'm pretty happy with its performance, and sold both of my 5050 to friends where they soldier on. The hot tip in Otari land is the MX-50 a grossly underappreciated machine that in most respects is a significant step up from the 5050. I have kept both of mine. I developed several high performance tape replay amps over the past couple of years - would be very interesting to compare notes and compare performance. My most recent design uses 4 discrete op-amps of my own design and sounds fairly good. (Better than the stock Otari electronics)
I am going to send a headblock with SAKI heads on it to be aligned by John sometime in the coming months and that will go on one of my two MX-50s.
Amy and I are doing well, and very busy with work. Walter's new listening room will be quite something to see and hear. Let's take this conversation to PM. I have other news.
Great to hear from you. I recently purchased a fully restored A810 from Dana, I'm pretty happy with its performance, and sold both of my 5050 to friends where they soldier on. The hot tip in Otari land is the MX-50 a grossly underappreciated machine that in most respects is a significant step up from the 5050. I have kept both of mine. I developed several high performance tape replay amps over the past couple of years - would be very interesting to compare notes and compare performance. My most recent design uses 4 discrete op-amps of my own design and sounds fairly good. (Better than the stock Otari electronics)
I am going to send a headblock with SAKI heads on it to be aligned by John sometime in the coming months and that will go on one of my two MX-50s.
Amy and I are doing well, and very busy with work. Walter's new listening room will be quite something to see and hear. Let's take this conversation to PM. I have other news.
stellavox: Studer "wrapped" digital around the analog circuitry including MANY A/D's to "easily" control signal levels and EQ boost/rolloff. These all take their "sonic toll".
Studer indeed used many AD7524s in the A810 audio circuitry. But these are not used in the typical analog-to-digital sense---such as 48 KHz (or higher) sampling converted to a 16 (or higher)-bit digital word, digitally processed in some way or another, and then converted back to an analog signal. Rather the AD7524 is used as a digitally-programmed attenuator in which the 8-bit data word is used to control combinations of resistors to control a specific audio parameter. This is not nearly as invasive as a total A-to-D, D-to-A conversion process would be.You are so correct: there is a big jump between consumer level stuff and studio-grade tape machines. I could never afford buying even a consumer-level tape deck in high school and college between 1970 and 1977, but I had opportunities to hear Ampex 350 (excellent), work with Scully (not that great), the consumer Revox A-77 (prone to mechanical break-down and parts took a long time to be shipped to us in Rhode Island), and finally the best deck I've heard and used: 3M M79 with the isoloop capstan system. Incredibly easy to thread (as the capstans tilted beneath the deck); wonderfully easy to razor blade edit on; great sound for the time. I think that 3M made a super M79 as a new model, before they ditched the tape machine business. I could be wrong, but many professionals and audiophiles prefer the 3M machines over the competing Studer, which I think is much more widely used and regarded as a top-of-the-line machine. Pity that our M79 was not outfitted with Dolby A.
I know the techs at my college radio station loved the 3M because they felt it was quite easy to service, compared to Ampex 350 or the Revox.
"I know the techs at my college radio station loved the 3M because they felt it was quite easy to service, compared to Ampex 350 or the Revox."
I beg to differ. I don't think that isoloop transport was easy to service nor reliable. It required perfect mechanical alignment to avoid wow, flutter, and tape skewing. This was much more evident on the 2" 24-track machines, for sure, but that stretch-the-tape-across-the-heads method of tape transport was a constant headache in my experience. The major advantage of the 3M-79 in the studios was its close proximity of the erase and record heads, making it the "tightest-punch-in" machine in the business. In addition, ALL of the audio electronics were on a single board for each channel, as opposed to the Ampex/Studer method of separate boards for bias, record, and reproduce. This made board-swapping quick and easy, with a minimum of realignment required to repair and continue the session.
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I beg to differ. I don't think that isoloop transport was easy to service nor reliable. It required perfect mechanical alignment to avoid wow, flutter, and tape skewing. This was much more evident on the 2" 24-track machines, for sure, but that stretch-the-tape-across-the-heads method of tape transport was a constant headache in my experience. The major advantage of the 3M-79 in the studios was its close proximity of the erase and record heads, making it the "tightest-punch-in" machine in the business. In addition, ALL of the audio electronics were on a single board for each channel, as opposed to the Ampex/Studer method of separate boards for bias, record, and reproduce. This made board-swapping quick and easy, with a minimum of realignment required to repair and continue the session.
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Dear Kevin,
Thanks a lot for this excellent and inspiring thread. It gave me enthousiasm to "attack" again my 5050IIb...I already started with some of the mods you posted at the beginning, with success so far.
Here, some of my exploits:
I purchased a non-working 5050IIb years ago and had it working both mechanically and electrically after some studying...I did not like the "stock sound", so I began "major surgery" (warn to the faint of heart here) which included:
I have a question for the wise after studying the schematics: is it not that the NAB/IECC selector only addresses the HF part of the EQ and NOT the Low Frequency differences on them???
Cheers and thanks again for your efforts.
M.
PS: I even made a cart fot it...
Thanks a lot for this excellent and inspiring thread. It gave me enthousiasm to "attack" again my 5050IIb...I already started with some of the mods you posted at the beginning, with success so far.
Here, some of my exploits:
I purchased a non-working 5050IIb years ago and had it working both mechanically and electrically after some studying...I did not like the "stock sound", so I began "major surgery" (warn to the faint of heart here) which included:
- Balun at AC power entry. I do it with all of my projects now.
- Independent double regulated power supply (28VDC to 20 to 14VDC) with TeddyRegs (small footprint) for the repro amp, which required some cutting to isolate that part of the PCB...watch that the PCB is rather odd and one might miss a link here and there.
- Replacing the stock ballanced outs (major contributor to heat) with THAT 1646 ballanced modules that I had on hand.
- Swapping signal coupling caps with Vishay Film (the green ones) 10uf which required some more cutting and drilling, and, you guessed it, some unwanted problems...
- Replacing stock opamps with OPA2604 in class A (with Rs) which IMHO sound very natural and "tape-like" ; I tried opa2132 and did not like it. I have a bunch of LM4562 but never had the courage nor the appetite to try them. I could not source op285 yet... as you may have guessed, 2604 at the first position (IC501) tends to oscillate (at least one channel did), even with rail-to-rail decoupling cap. So yesterday I did the power-pins-to-ground decoupling anf it is working fine until now...
with the stock opamp in that position it sounds rather dull... - I also did many DIY upgrades to the transport system as the ones here--> https://bottlehead.com/product/otari-mx-5050-bii-biii-tape-path-modification-kit/ bearings instead of fixed metal on the tape thread and structural "L" angled aluminium tension arms (instead of the proposed steel ones), everything very cheap and which works fine, after adjustments. Use uninportant tape to test these mods...
I have a question for the wise after studying the schematics: is it not that the NAB/IECC selector only addresses the HF part of the EQ and NOT the Low Frequency differences on them???
Cheers and thanks again for your efforts.
M.
PS: I even made a cart fot it...
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Hi Max,
Quite the odyssey there, a very determined and persistent modder.
I have confirmed that both NAB and IEC playback EQ in the BII-2 and MKIII-2 were accurate to at least the stated tolerances in the manual. The NAB LF EQ is accomplished by shunting the high value feedback resistor with a much lower value, that moves the LF pole to about 50Hz (3180us) and then it rolls off with a 90us time constant until it hits the knee at around 1770Hz.
I have a couple of MX-50s and external tape amp I use with one of them. (Based on discrete op-amps it's not quite where I want it to be yet.)
The MX-50 has significant transport improvements over the MX-5050 but is not nearly as common.
I replaced many parts and modded the MX-5050s, but the MX-50s are still stock except for the replacement parts. I am thinking that all of those terrible carbon/bakelite trimmers should go. I was having very erratic transport behavior in the older MX-50 and replaced all of the pots in the BLDC servo circuitry - night and day. I used Piher cermet, and am planning the same for the audio in that one - then maybe some op-amp upgrades. I may try the OPA2604 or my old standby the OPA1642 on an adaptor. I have a very limited number of THAT TH1646 and they are currently unobtanium so I am not sure whether I will use them, but the MX-50 has unbalanced outputs on XLR and real balanced would be nice. The voltages in the MX-50 are much higher than MX-50 which presents a challenge.
Thanks dear, for the info.
A dedicated low noise regulated supply is really worth it.
I swapped long ago the repro volume pot for a SMD resistor attenuator (only one shaft) which sounds identical to the SRL out. The original degraded/colored the sound quite a bit.
I replaced for now VR103/203 (71/2ips) for your typical "bourns" (3296?) variable resistor soldered to the bottom. I do not know if it sounds better or not but certainly it sounds way cleaner now. What would be the lowest noise pot we can use there?
I decided to bypass VR106/206 since my SMD resistor attenuator sounds so transparent (it can manage the volume on its own) and it turned out to be a good move.
With these mods, and several capacitor replacement that you recommended, now the machine is clean sounding. Lots of clicks and weird noises have disappeared... more importantly, no apparent oscillations with the decoupling caps from power pins-to-nearest-ground, for OPA2604 as IC501.
About external repro preamplifiers: indeed I was searching for them when I stumbled upon your thread. The previously quoted tesis about "transresistance preamp" showed a Crown discrete preamp and their siblings can be found on hifiengine, with Studer B62 which is also feasible. The hard part would be the several speeds and the bias circuit and adjustement...
https://www.hifiengine.com/manual_library/crown/pro-800-series.shtml
*The head pressure brushes seem like a good idea/mod...
I will try to take good pictures of the transport mods.
Cheers everybody,
M.
A dedicated low noise regulated supply is really worth it.
I swapped long ago the repro volume pot for a SMD resistor attenuator (only one shaft
) which sounds identical to the SRL out. The original degraded/colored the sound quite a bit.I replaced for now VR103/203 (71/2ips) for your typical "bourns" (3296?) variable resistor soldered to the bottom. I do not know if it sounds better or not but certainly it sounds way cleaner now. What would be the lowest noise pot we can use there?
I decided to bypass VR106/206 since my SMD resistor attenuator sounds so transparent (it can manage the volume on its own) and it turned out to be a good move.
With these mods, and several capacitor replacement that you recommended, now the machine is clean sounding. Lots of clicks and weird noises have disappeared... more importantly, no apparent oscillations with the decoupling caps from power pins-to-nearest-ground, for OPA2604 as IC501.
About external repro preamplifiers: indeed I was searching for them when I stumbled upon your thread. The previously quoted tesis about "transresistance preamp" showed a Crown discrete preamp and their siblings can be found on hifiengine, with Studer B62 which is also feasible. The hard part would be the several speeds and the bias circuit and adjustement...
https://www.hifiengine.com/manual_library/crown/pro-800-series.shtml
*The head pressure brushes seem like a good idea/mod...
I will try to take good pictures of the transport mods.
Cheers everybody,
M.
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I knew this existed, it is how the Germans started; but never seen a mention in the US.
Really odd: "...in bulk in varying widths..." While slitting machines were common for other paper products, recording grade slitting was usually considered a real specialty. And WTF is "varying widths"?? When we bought newsprint for the weekly shopper, we got the width we ordered. Any "varying" would jam the press (actually Tony would not even load ratty-size paper).
Really odd: "...in bulk in varying widths..." While slitting machines were common for other paper products, recording grade slitting was usually considered a real specialty. And WTF is "varying widths"?? When we bought newsprint for the weekly shopper, we got the width we ordered. Any "varying" would jam the press (actually Tony would not even load ratty-size paper).
Brush is offering to sell bulk lengths in different widths other than the standard 1/4" wide tape. What is so unusual about that? One presumes that Brush either operates its own paper tape slitter; or it can order a custom width special from the company that makes the paper tape for them (to Brush's specifications) - if the bulk minimum for that supplier is met.
WRT head re lapping discussion (some time ago), it can be a little more challenging on wider pro formats.
Shown here I use a flat ground glass surface plate, Toolmkaers ground parallels to build height and a Toolmakers cylinder square to check the heads perpendicular accuracy.
Wider tape formats such as 1" and especially 2" can take a little more time to get right. Also shown 1/2" repro head after re lapping.
Terry
Shown here I use a flat ground glass surface plate, Toolmkaers ground parallels to build height and a Toolmakers cylinder square to check the heads perpendicular accuracy.
Wider tape formats such as 1" and especially 2" can take a little more time to get right. Also shown 1/2" repro head after re lapping.
Terry
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HELP! Otari MX-50N-II Made in 1992
Help needed. I picked one of these up for $499.00 at a thrift store. I tested it and everything seemed to work however I neglected to check to the capstan! The item does not appear to be mistreated or over used. I have until this Saturday to return if I can not get it going.
The capstan moves very smoothly with my hand, other than that it is completely dead. It does not seem to be seized. I have used deoxit on all buttons with no response from the capstan motor, checked fuses and looked for soldier cracks on the boards. All looks good.
I know the MX-5050 has a switch (V-5-1A44 UND.LAB.INC) that often needs to be cleaned to turn on the capstan motor. I have not found a switch like that on the MX-50N.
The following video shows that switch.
I am a novice any suggestions would be greatly appreciated. Thanks.
Help needed. I picked one of these up for $499.00 at a thrift store. I tested it and everything seemed to work however I neglected to check to the capstan! The item does not appear to be mistreated or over used. I have until this Saturday to return if I can not get it going.
The capstan moves very smoothly with my hand, other than that it is completely dead. It does not seem to be seized. I have used deoxit on all buttons with no response from the capstan motor, checked fuses and looked for soldier cracks on the boards. All looks good.
I know the MX-5050 has a switch (V-5-1A44 UND.LAB.INC) that often needs to be cleaned to turn on the capstan motor. I have not found a switch like that on the MX-50N.
The following video shows that switch.
I am a novice any suggestions would be greatly appreciated. Thanks.
Did you load tape onto the machine? I have an MX-50N, and an MX-50NII both needed a complete recap.
Does the capstan pulley solenoid pull in? It does not run at either 7.5ips or 15ips? Does not respond to position of the tension arm?
I paid the same sort of money for each of mine in non-running condition, but was comfortable with the risk and was able to fix both of them. IMO they are better performers than the ubiquitous MX-5050 BII-2.
It has been a long time since I messed around with these machines, and they are quite complex and not easy to fix if you not know what you are doing.
If the capstan motor is actually nonfunctional it would be best to return for a refund, otherwise the price is reasonable for a project deck. (Good working ones sell for as much as $2K although some sellers ask more)
Does the capstan pulley solenoid pull in? It does not run at either 7.5ips or 15ips? Does not respond to position of the tension arm?
I paid the same sort of money for each of mine in non-running condition, but was comfortable with the risk and was able to fix both of them. IMO they are better performers than the ubiquitous MX-5050 BII-2.
It has been a long time since I messed around with these machines, and they are quite complex and not easy to fix if you not know what you are doing.
If the capstan motor is actually nonfunctional it would be best to return for a refund, otherwise the price is reasonable for a project deck. (Good working ones sell for as much as $2K although some sellers ask more)
Download the service/operators manual for the MX-50NII, and consult it for more details. The MX-5050 is a very different machine in a lot of respects.
Most of the circuitry in the N and NII is identical except in the headphone monitor circuitry. Make sure you are not in cue mode. (Capstan motor does not run in this mode.)
Most of the circuitry in the N and NII is identical except in the headphone monitor circuitry. Make sure you are not in cue mode. (Capstan motor does not run in this mode.)