Shirley Laboratories TW/PA Tape amp information

[Goodizzy]

Does anyone have any further information on these tape amps? They seem like a very nice, semi-professional variant of the 60s Brenell/Ferrograph/Vortexion decks. Apparently, the TW/PA series of tape amps were designed for professional use, although I don't see input transformers on the input jacks. Shirley Laboratories was out of Worthing, Sussex I believe.

The article I found regarding one of these, the TW/PA4, appeared in The Tape Recorder magazine from Feb-Apr 1963.

Here are the links and page numbers:

http://www.americanradiohistory.com/...nd-1963-02.pdf (pg 20-23)

http://www.americanradiohistory.com/...nd-1963-03.pdf (pg 21-24)

http://www.americanradiohistory.com/...nd-1963-04.pdf (pg 23-26)

They intrigue me as they separate out the record and replay amps and use a dedicated valve for the bias oscillator. I am interested in building a rackmount version of this for a Brenell MK5 gold I am going to put in a custom rack.

Has anyone built this in the past? Thoughts on the circuit? Adding input and line transformers? Is the circuit worthwhile enough? I've been looking over Ferrograph tape amps, Sterns Type C as well as the Mullard variants and this looks to be the best of the lot.

Is it feasible to do without the specific inductor values?

I appreciate any insight!

[vidjoman]

Looks very similar to the circuit of the Brenell Mk5M. Separate record and replay amps and I think it also had mixing for Mic and Line inputs. Also had a separate erase/bias supply. Had one when new and it was excellent.