Why not use a tape recorder for playback?

Fred Thal

[Industry Expert]
Jul 15, 2016
161
11
123
Using a three-head tape recorder (technically known as a recorder / reproducer) for playback remains a common practice. Yet tape playback through a recorder / reproducer can never provide optimum performance, in part due to the location of the playback head in the headblock.

Consider that the primary purpose of the playback head on a recorder / reproducer is to provide confidence recording capability. This feature allows an operator to monitor the signal coming back off the tape, assuring that a recording is taking place satisfactorily.

How to achieve the highest quality tape playback?

Analog tape machine designers have known since the 1960s that the solution for attaining highest quality playback is a specialized machine optimized for this purpose. Such playback machines are known as reproducers. Reproducers never have erase or record heads. The better reproducers (including those from ATAE) have only a single playback head that has been optimally positioned in a special headblock design.
 

topoxforddoc

Well-Known Member
Feb 20, 2015
67
6
138
Cheltenham, UK
Yup, I get it :)
 

Fred Thal

[Industry Expert]
Jul 15, 2016
161
11
123
Yup, I get it :)

Good. Thanks Charlie.

It needs to be emphasized that chasing down scrape flutter with improved headblock design has very limited application.

It won't be of much, if any benefit to most people.

And fitting a low-scrape flutter headblock design to conventional, force-guided transport is only an exercise in futility.

The reason is that time-base errors like flutter in an analog tape transport are additive and cumulative.

The flutter adds successively in layers and then convolves.

This fact of course is the huge technical challenge we face in analog audio tape replication.

If there is significant audible scrape flutter already "recorded-in" on a typical, low-quality tape copy (as is commonly the case), then why go to the trouble and expense of playing it back on a state-of-the-art reproducer having almost no flutter?

At best, all you can ever hear is the corrupted time-base of the low-quality tape copy. So why even care?

But let's imagine for a moment that we have real master tapes. (Remember, some people actually do.)

In this special case, one might cogently argue that the reproducer chosen for playback, indeed ought to be a state-of-the-art design.

Ideally, this state-of-the-art reproducer should have flutter that is lower, by an order of magnitude, than that of the recorder that originally made the master tape. That way, on playback we will hear only the artifacts of the original recording. We will not be adding any more.

For accomplishing that, you'd need to start with a precision guidance tape transport. The old Studer A80 and A820 machines are by far the most common surviving examples of such expensive to construct designs. These are the models we start with to build our reproducers. (Other Studer models, not being precision guidance, do not qualify.)

The elephant in the room is to never mention that the record labels and the top mastering houses, who are working with legacy analog master tapes, are still not using state-of-the-art reproducers having such vanishing low levels of flutter. Many of them are still using force-guided transports in their mastering suites today.

One might conclude that they must believe that the public would not (or could not) ever hear the benefit.

So they go on using the same old tape machines for master tape playback that they've always been using.
 

microstrip

VIP/Donor
May 30, 2010
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Portugal
Just one question - in what category fall the german made Telefunken M15 and M20? The M20 looks more like a precision guidance tape mechanism, but I have only seen pictures, I never watched one running.
 

Fred Thal

[Industry Expert]
Jul 15, 2016
161
11
123
The M20 looks more like a precision guidance tape mechanism, but I have only seen pictures, I never watched one running.

Hi microstrip,

You are correct to guess that the M20 transport itself was essentially a precision guidance design, but its headblock uses forced guidance.

That said, the forced guidance in the M20 headblock was one of the best ever designs of this type. (Vastly superior to the Ampex implementations, for example.)

M15s are disqualified for consideration as candidates for building into a s.o.t.a. transport, due to their primitive means of establishing constant tension.

In my opinion.
 

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