Single Head Repro Only Solution for External Tape Repro Preamp

Ron Resnick

Site Co-Owner, Administrator
Jan 24, 2015
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Fred, accepting our somewhat conflicting and somewhat non-technical audiophile objectives, please help us figure out an optimal external tape repro solution for us and, maybe, a new ATAE product for you.

1) We want to be able to use an external repro preamplifier of our choosing.

2) We understand that the tiny signal coming off the playback head is very low in voltage and very susceptible to loss in a wire of even short length.

3) We understand that the inductance and capacitance of that wire may screw up the signal coming off of the playback head.

4) It makes sense to me, for one, that that direct head out wire must be very carefully matched to the electrical characteristics of the playback head.

5) So maybe we are sympathetic to having a "pre-preamplifier" in the headblock itself. A pre-preamplifier allows a larger signal to flow into the direct head out wire and, presumably, takes some pressure off the need for that wire to be as short as possible, and to be as finely tuned to the electrical characteristics of the playback head as would be the case if we were not using a pre-preamplifier built in the playback head.

6) But being audiophiles we are suspicious of op-amps and ICs. (Yes, I am well aware that the first amplification stage of Nick Doshi's tape repro preamp is an op-amp. For whatever reason many fans of the Doshi preamp are willing to overlook this element.)

7) So can you make a "drop-in" SHRO headblock with a pre-preamplifier made of discrete components? If not truly "drop-in" then a configuration which a reasonably competent tape machine technician (meaning not only the former head of the engineering department at Studer!) can install successfully?

8) How do we get the direct head out wire and connection accomplished?

A) Should you select the wire yourself and include the wire by hard-wiring the signal wire into this SHRO headblock so there is a 1 meter interconnect terminated in XLR plugs coming out of the headblock which we simply plug into the external repro pre-amp after the headblock is installed?

B) Should there be XLR jacks on the back of the headblock or in a box which comes with your product and which we can place on the side of the machine and then use interconnects of our own choosing (and your approval) to send the signal from this connection block to the external tape repro preamp?​

9) If we use a pre-preamplifier in the headblock then does that vitiate our use of the generally available external tape repro preamplifiers? Would using a pre-preamplifier and an external tape repro preamp result in too much gain?

(Does anyone know if the op-amp gain stage in the Doshi pre-amp can be bypassed since a pre-preamplifier in the headblock would result in lower gain being needed in the external tape repro preamp?)


PS1: Fred, I stipulate that you are the world's leading technical authority on Studer machines. If this is to be a mutually productive discussion you have to accept that we audiophiles sometimes like what we like for reasons which do not make valid technical sense to you.

PS2: In my questions to Fred I use the collective tape enthusiast "we." If my point does not represent accurately your personal view, please don't worry about it. :)
 

Bruce B

WBF Founding Member, Pro Audio Production Member
Apr 25, 2010
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www.pugetsoundstudios.com
Fred has already solved this problem in the A80 with XLR output connections via the Repro cards. I believe this is what you are asking??


XLR.JPG
 

Ron Resnick

Site Co-Owner, Administrator
Jan 24, 2015
16,017
13,346
2,665
Beverly Hills, CA
That is one way to answer the question about how to achieve the direct head out connection, certainly.

But I believe Fred does not love the intermediate connection required by jacks.
 

Fred Thal

[Industry Expert]
Jul 15, 2016
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We want to be able to use an external repro preamplifier of our choosing.

Understood. To accommodate your wishes, we offer you five.

So maybe we are sympathetic to having a "pre-preamplifier" in the headblock itself.

Excellent. This is the technically best approach to correctly matching the first stage to any particular repro head.

So can you make a "drop-in" SHRO headblock with a pre-preamplifier made of discrete components?

Yes.

If not truly "drop-in" then a configuration which a reasonably competent tape machine technician (meaning not only the former head of the engineering department at Studer!) can install successfully?

Caution, please slow down. This and your remaining questions will drag us deep into the technical weeds.

Yet, they are certainly all very good questions. And all covered in depth, in a couple of ATAE white papers that are in the appendix of the manual you'll receive as a purchaser of a Model One or Model Two.

These topics are also covered in your four-day, Model One (or Model Two) operator training course.

By the way, almost the first thing you will do in class on day one, is completely take apart an old Studer A820.

That will very quickly help you understand why the Model One is not at all assembled like the Studer was.

Yes, I know, the prospect of spending four nights in a Holiday Inn near Sacramento for our training can be off-putting.

But thankfully, our Holiday Inn is co-located with what is a rather decent (San Francisco based) restaurant.

On day four, you may optionally tour the nearby Pass Labs factory. They would be happy to receive you.
 

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