TP-028, Nat Adderley's Work Song is now available

Author Topic: MX-5050B2HD on the bench today.  (Read 18781 times)

Offline docb

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Re: MX-5050B2HD on the bench today.
« Reply #15 on: November 15, 2008, 03:00:00 PM »
Your intuition is good, Ben - ball bearings on the tension arms is where we started and it was definitely an audible improvement, particularly on the supply reel side. Even if we only offered that as a mod I think folks would hear the improvement. Regarding the tape wandering, the guides are .250" wide just as they were in the stock config. I have the impression that it's a matter of the tape lifting on one edge rather than side to side wandering. But that's not for sure. And the head does have some wear, so maybe it is indeed climbing up over the edge of the wear groove, or maybe it is getting twisted off the head by some alignment issue.

Here's an interesting observation - if you grab the impedance roller and hold it so the tape drags over it without turning it the bobble seems to smooth out. So it may be a speed control issue.

Speaking of wear, we were so worn out from thrashing that and dealing with a couple of priority items for customers the past couple of days that we decided the best thing to do was stay away from it for a couple days and come back with a fresh outlook.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline ironbut

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Re: MX-5050B2HD on the bench today.
« Reply #16 on: November 15, 2008, 05:29:08 PM »
Speaking of wear, we were so worn out from thrashing that and dealing with a couple of priority items for customers the past couple of days that we decided the best thing to do was stay away from it for a couple days and come back with a fresh outlook.
Always a good idea IMHO! I don't know about Washington state, but the weather down here is glorious. Maybe it's a good weekend to take Ansel Schmalle out for a walk?
steve koto
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Offline docb

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MX-5050B2HD off the bench today and into a system
« Reply #17 on: November 20, 2008, 10:19:31 AM »
After two weeks of repairing, adjusting experimenting, listening, customizing, etc., Shawn got the once beat up old MX-5050B2HD ready for some listening yesterday. I must say it was most pleasant to hear how it came out! We compared against a stock Otari and the improvement was pretty dramatic.

First job was repairing a broken power transformer mounting saddle and some broken and corroded board connections. This work got the machine into basic functionality. Shawn spent some time learning the standard set of adjustments in the Otari service manual to get the machine squared away to their spec. And we did several mods. I have mentioned the installation of ball bearings on all of the fixed guides on the head block ( a real pain to do!) and adjustable ball bearing guides with ceramic edge guides on the lever arms. An Athan urethane pinch roller was installed. Also, the stock brake pads were terribly grabby and really messing up the way the machine pulled tape. After some thorough cleaning of the drums and failure to get the stock pads to quit grabbing, Shawn relined the brake shoes with some real wool felt that I had originally purchased for an unsuccessful attempt at upgrading Technics brakes. On the Otari this stuff is da' bomb, making for very smooth action. With these mods the machine needed a lot of fine adjustment from tweaking the brakes by using multiple springs (very finicky), to head wrap to experimenting with just the right number of shims on the new ball bearing guides to get the tape to run perfectly flat and smooth on the heads.

And of course the head cable connections to the internal electronics were bypassed so we could use an outboard repro amp. We did the same on a stock 5050 that had been thoroughly gone through, so that we could compare. Comparisons were done with the Tube Repro, a S.E.X. amp and Sennheiser HD 600s with Cardas cable.

The improvement in dynamics and clarity is really impressive. Much to my surprise the Otari lives up to its rep and begins to approach the sound of the "real" studio machines. It doesn't have the last bit of super stable tone and quick articulate sound of an ATR or my new Nagra T. But I would say that as a machine you can pick up for beans these days it makes into an awfully good transport once modded to get rid of all of the friction causing surfaces in the tape path.

I know that a lot of you were hoping for an inexpensive kit of parts for a DIY deal, and I had hoped that we could say, "OK, just buy these parts, install them and your machine will sound improved". But it turns out that between tapes guides held together with some truly nasty thread locker, brake pads that need to be relined and several tweaky adjustments that need to be made to get the tape to travel flat over the heads we have created another mod that requires a fair amount of work and specialized equipment to really dial in. So I think we will have to offer the same kind of mod service as we do with Technics machines to be able to ensure that the parts will work as intended. The Otari mod uses a lot more of the rather spendy ball bearings - 14 in the Otari vs. 6 in the Technics. But the labor may end up being a bit less so we will try to cook up a price that is in the ballpark of the Technics mod.

Some of you will ask "is it better than the modded Technics?" I would say it sounds different, like different styles of turntables have different strengths. The Technics has a very smooth and liquid quality to it with speed stability that is really great, and is certainly the winner for looks. The Otari has a sense of dynamics and liveliness as its strength, and the stock head may have a bit more output than the stock Technics head (after taking both of them apart I no longer think they are exactly the same head, though they are very similar). Both transports are good tape handlers, so it comes down to choosing the flavor you like. Neither transport is quite as good sounding as an ATR or Studer or Nagra T. These big machines just take the good qualities of both a bit higher. But in modded form both the Technics and the Otari get a lot closer.

Kudos to Shawn for staying in the fight with this machine. I was ready to give up about a week into the struggle but he hung in there and eventually ended up with something that really sings.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline xcortes

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Re: MX-5050B2HD on the bench today.
« Reply #18 on: November 20, 2008, 10:25:23 AM »
congrats!
Xavier Cortes

Offline ironbut

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Re: MX-5050B2HD on the bench today.
« Reply #19 on: November 20, 2008, 07:23:12 PM »
That's fantastic news! I really believe that it's a good idea for many of us, to take or send our machines in at least once, to someone with all the proper equipment and knowledge to really get it running right. If you've never owned a particular machine or haven't for a long time, you'll never know if it's living up to it's potential or even damaging your Tp tapes. I'm glad to hear that Xavier did and I'm sure that's he'll be stoked when I hears the improvements that you'll make on his Technics. I don't feel comfortable telling folks how to spend their hard earned cash so I feel like their having to send their Otaris to you is a good thing.
steve koto
 Sony scd 777es(R. Kern mods)> Vpi Aires>Dynavector XX-2mkll>Bent mu>CAT ultimate>CJ premeir 140>Magnepan 1.6qr(Jensen xover)Headphone Eddie Current Zana Deux>AT ad2000,HD800 ,Metric Halo ULN-2 (battery powered),
 HE Audio Jades