Otari under the knife

[kcin]

Not willing to let well enough alone and while I'm waiting for my tape path replacement parts ( pinch rollers, arms and bearings etc) to improve performance
I opened the MX5050 up and checked the ESR of the power supply caps and they were tired.

So, I ordered 6 low ESR high temperature caps and the intended RCA output jacks for my direct output plan from the heads & I replaced the caps and measured my voltages-- all good now.

I think i will put in a switch to toggle between the Otari pre and the intended direct out tube pre that I will put together. I'll use the mic in spots for the direct out and just heat shrink those wires and tie-wrap them off.

Its amazing whats in these machines the amount of work it was to put them together. Looking forward to the project. the Mechanical pieces should arrive next week, hopefully- I'll put those in and take it in to align the tape path set azimuth and levels etc as I don't have the test tapes to carry that part out.

[astrotoy]

Very impressive! I never had the courage to pull the cover off my Otari. I had a friend check the insides of mine, but thankfully he did it in his workshop, so I wouldn't faint.

Larry

[RoadDawgWest]

Looks fun. Which external tape preamplifier, Bottlehead Eros?

[jcmusic]

I would speak with John French about his opinion on the tape path mods, he told me it may not be the way to go.

[kcin]

I don't know who John French is ,unfortunately,... convenience & reversibility will have to be balanced with sound quality.. I will experiment with cables and routing. I'm OCD on that stuff.

[user510]

Thanks for documenting this process. I'll follow the project with interest. Partly because I've been 'under the hood' on mine but also need to go back under again sometime in the near future. So far, those internal organs look familiar.
-Steve

[kcin]

Looks fun. Which external tape preamplifier, Bottlehead Eros?

I am building my own tube design based on a phono pre I built - I'll add the requisite eq for the tape unit.

I also am going to pick up a deHavilland as I like that unit and I think it provides good value and sounds real nice based on my experience with others. I've ordered it this week .

I just hate the wooden box look and while I appreciate the Bottlehead efforts ------I didn't want to invest in an Eros- I don't like tape that much---between my own design & the deHavilland I'll keep the one I like best. The home brew phono pre sounds good and I shared some of these with the circle of audio nuts around here -I'm hoping my latest thoughts on it will transfer well to the tape.

I have a special need. Anything I do will have to drive my amp direct, as I won't go through another line stage to do this and I need 2 outputs as my Direct Drive amp for the Beveridges is bandwidth limited with a 1st order crossover at about 100Hz everything below that goes to my bass amp/subs. My design and the deHavilland will accommodate this.

This is all I'll do on tape it is a deep dive for me.... I am absolutely not interested in shifting my software to tape. If a Ampex or something lands on me for a $1 I'll go for it otherwise this a diversion. I like tinkering- keeps me out of the bars and such .... and I get to use my noodle & see if I can put what I learned in school back to some practical use.

Stay tuned.

[kcin]

Looks fun. Which external tape preamplifier, Bottlehead Eros?

My own design and a deHavilland 222 best man wins.

[RoadDawgWest]

I am building my own tube design based on a phono pre I built - I'll add the requisite eq for the tape unit.

I also am going to pick up a deHavilland as I like that unit and I think it provides good value and sounds real nice based on my experience with others. I've ordered it this week .

I just hate the wooden box look and while I appreciate the Bottlehead efforts ------I didn't want to invest in an Eros- I don't like tape that much---between my own design & the deHavilland I'll keep the one I like best. The home brew phono pre sounds good and I shared some of these with the circle of audio nuts around here -I'm hoping my latest thoughts on it will transfer well to the tape.

I have a special need. Anything I do will have to drive my amp direct, as I won't go through another line stage to do this and I need 2 outputs as my Direct Drive amp for the Beveridges is bandwidth limited with a 1st order crossover at about 100Hz everything below that goes to my bass amp/subs. My design and the deHavilland will accommodate this.

This is all I'll do on tape it is a deep dive for me.... I am absolutely not interested in shifting my software to tape. If a Ampex or something lands on me for a $1 I'll go for it otherwise this a diversion. I like tinkering- keeps me out of the bars and such .... and I get to use my noodle & see if I can put what I learned in school back to some practical use.

Stay tuned.

The reason I asked, was that I was thinking about doing the same, building my own. I now work in software, and felt it could be interesting to go back to my roots, and apply my education as well.

Good luck with the project. I'll be interested in reading how this progresses, and learning more about the deHavilland 222.

[jcmusic]

I would speak with John French about his opinion on the tape path mods, he told me it may not be the way to go.

John French is the owner of JRF Magnetics, I talked to him about the bearing mode last week and his story was not in favor of it!!!

[kcin]

Thanks I thought your reference was to the tape out direct mod. thanks.

[jcmusic]

I am building my own tube design based on a phono pre I built - I'll add the requisite eq for the tape unit.

I also am going to pick up a deHavilland as I like that unit and I think it provides good value and sounds real nice based on my experience with others. I've ordered it this week .

I just hate the wooden box look and while I appreciate the Bottlehead efforts ------I didn't want to invest in an Eros- I don't like tape that much---between my own design & the deHavilland I'll keep the one I like best. The home brew phono pre sounds good and I shared some of these with the circle of audio nuts around here -I'm hoping my latest thoughts on it will transfer well to the tape.

I have a special need. Anything I do will have to drive my amp direct, as I won't go through another line stage to do this and I need 2 outputs as my Direct Drive amp for the Beveridges is bandwidth limited with a 1st order crossover at about 100Hz everything below that goes to my bass amp/subs. My design and the deHavilland will accommodate this.

This is all I'll do on tape it is a deep dive for me.... I am absolutely not interested in shifting my software to tape. If a Ampex or something lands on me for a $1 I'll go for it otherwise this a diversion. I like tinkering- keeps me out of the bars and such .... and I get to use my noodle & see if I can put what I learned in school back to some practical use.

Stay tuned.

I have the Bottlehead Tube Repro and the deHavilland Model 222, I like both they sound very close in sound quality. The Tube Repro is on my Otari and the deHavilland was on my Studer. The tubes used in either unit will play a big roles in how it sounds, I used the best tubes I could find they were not cheap...

[kcin]

I have the Bottlehead Tube Repro and the deHavilland Model 222, I like both they sound very close in sound quality. The Tube Repro is on my Otari and the deHavilland was on my Studer. The tubes used in either unit will play a big roles in how it sounds, I used the best tubes I could find they were not cheap...

Good to know- I appreciate the comment-anything more specific contrasting the two would be appreciated. I have a huge inventory of tubes so I'm sure I will find something that works!

[Dr.Ears]

Stick with black plates, no gray plated tube ever made it into my reference system, neither has any GE or Sylvania NOS tube. I can't give you a reason as to why, but I stopped wasting my money a long time ago.

[kcin]

I guess I'll throw out my Amperex, Siemens, Telefunkens and Mullards

[Dr.Ears]

Telefunkens are the only tubes on your list that I have not seen in black plates. I had the Tele' combo of 12AU7 & 12AX7 in a pre-amp and found them to have a bloated mid-range. I preferred the Siemen's black plated combo and the Mazda chrome plated 12AX7's.

[kcin]

Further progress as I orient myself around this deck.

I have direct wired the heads out with pure silver conductor shielded cables 1m out of the deck and I passed them through some nylon sealtite connectors so you can't pull them out of the deck --these will go directly to my new pre-pro.

All of the inputs and outputs are converted to single ended as that is what I use in my system. The mic inputs got taken out and the corresponding wires were heat shrinked and tied off internally. I have a terrible singing voice and I'll never use the microphone input.

I used the mic input jack space to re-arrange the back panel inputs and outputs to allow for the direct outputs (above) and to align with the wire lengths available for the internal cables still used for the jacks.

I drilled for two new RCA input jacks that are connected to input of the internal pre- pro---- all I have to do is patch my cables from the direct out to these jacks and its back to normal use of the internal pre- pro. I was going to use a switch here to toggle but I decided to eliminate the contacts in the direct line path and have the extra jacks only (if) using the internal pre- pro-- makes more sense... so I am truly direct out and have flexibility.

I made a new cable assembly with new molex connector to connect the internal amp to the RCAs off the board out of the same pure silver shielded cable.

Everything is reversible except for the two drilled RCA holes... there were small 1/8" holes already there from the factory but I enlarged them. If someone ever wants to go back to stock a couple of black hole plugs and put back the XLRs and none is the worse for wear.

I continue to recap the electrolytics which is a PITA as the board is not great quality but the access and thought to servicing is second to none. Revox , TEAC , Technics, Pioneer and the like are horrid in comparison. This is really well thought out and semi- pro quality in terms of ease of service.

I'm not sure how DIY most are on this board ... but I find it relaxing with a bit of a challenge to set myself down on the bench and work through something like this.

More to come as I deal with the tape path and perhaps the heads.. I've got conflicting reports as to replace/relap the heads they are probably 1/2 worn-- we'll see

[Rob]

which tape preamp did you choose?

[kcin]

Building my own and I have the Dehavilland 222 on order. Best man wins. Thanks.

[dminches]

Looks great. Do you have an pictures of the wiring out of the playback head?

[kcin]

I could probably get a shot if you are interested in it. thanks.

[dminches]

I would be interested if it wasn't a hassle to take one.

[kcin]

New parts in for Otari.. I will try to get them in this week. This time tape path parts: new pinch roller and take up arms with some oil. The Bottle head kit still to arrive and the the heads are at JRF.

[audioguy1958]

I'm really interested in any mods you make to the Otari's tape path. I have an MX5050 B2 sitting in a corner and I've thought about modding it, including a recap. I've thought about replacing the studs on the tension arms with rollers like my Tascam decks use.