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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 17th Mar 2022, 7:59 am   #81
david freeman
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Just wondering how far we got with this thread?
Interested to find out the conclusions as to why the Transistorised Playmaster was so bad.
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Old 17th Mar 2022, 10:55 am   #82
Ted Kendall
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

I have this on the bench but it has been pushed aside by the merely urgent. What I can say is that the switching around TR2 claimed in the published circuit description doesn't happen. There is a spare way on the R/P switch but no frequency selective NFB to generate a replay curve. On this point, Tutchings was on the money. In trying to make this work, I may find why Fidelity didn't...
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Old 17th Mar 2022, 6:23 pm   #83
david freeman
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

The Alec Tutchings review has a footnote.
To the effect that, since the submission of the review sample, Fidelity had informed him that they had made substantial changes to the Transistorised Playmaster, resulting in improved frequency response, and reduced hum and noise.
One wonders whether the circuit description, which mentions top lift in the record circuit is in fact, the “revised” version.
I noted that in the specifications, “amplifier playback response to CCIR standards”, is given.
Perhaps this is the model they should have made in the first place?
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Old 17th Mar 2022, 8:29 pm   #84
Ted Kendall
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Who knows? The review of the revised version never appeared.
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Old 18th Mar 2022, 2:37 pm   #85
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Mr Tutchings was always fair as far as I can see. I remember reading a couple of reviews where the machine had a fault - a Uher and a Telefunken, ISTR. In the former case he disregarded a problem that was obviously a 'one off', and in the latter his remarks were taken on by the manufacturer and they modified the machine.
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Old 18th Mar 2022, 6:25 pm   #86
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Agreed, Tutchings' judgement was sound. He designed the Gramdeck and made language lab systems using TD2 decks, so he knew about things on the other side of the fence. When the Revox A77 Mk2 came out, his review was a masterpiece of thoroughness, chasing and quantifying odd cross track erase funnies.
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Old 19th Mar 2022, 8:15 am   #87
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Looking through 60s tape recorder magazines it's noticeable how few British machines were placed under Aec Tutchings' microscope. I suspect the manufacturers were too frightened to submit them!

Certainly your standard Grundig or Philips etc would a have a decent level of basic technical competence. With designs like the Fidelity under discussion you wonder if any technical testing was done before it was released to production!

Tutchings himself seems to have been a busy bee, his day job was apparently with Sanders Microwave (later part of Marconi Instruments), certainly somehow he persuaded them to build the Gramdeck.
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Old 22nd Mar 2022, 1:04 pm   #88
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

My school had a Tutchings Electronics language lab. It comprised two TD10s and a switch unit so the teacher could listen in to any pupil without them knowing. Each station had a small box housing a headphone and microphone jack socket, an input DIN and a wirewound volme control.
It was later replaced with a Tandberg system and I got some of the equipment to play with. Each wooden box contained a Newmarket amplifier PCB which came in very handy for all sorts of projects!
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Old 23rd Mar 2022, 7:07 am   #89
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

I'm a bit surprised that the transistorized circuit can provide enough drive voltage for the EM84; I would have thought a transistorized circuit and associated low impedance head would have resulted in a fairly small voltage swing from the amplifier output.
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Old 28th Mar 2022, 10:09 pm   #90
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Just stumbled across this, a 'Westminster' playmaster 4 track. Never seen one in the flesh, must be a fairly rare variant.
Was this also transistorised? The colour scheme looks similar to the transistorised Fidelity.
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Old 28th Mar 2022, 10:38 pm   #91
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

So is this Westminster actually also designated Playmaster ?

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Old 28th Mar 2022, 11:11 pm   #92
Ted Kendall
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Quote:
Originally Posted by ben View Post
Just stumbled across this, a 'Westminster' playmaster 4 track. Never seen one in the flesh, must be a fairly rare variant.
Was this also transistorised? The colour scheme looks similar to the transistorised Fidelity.
I'd say that's a valve job - the transistor deckplate doesn't have vents.
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Old 29th Mar 2022, 3:24 am   #93
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Recording indicator? Could that be a magic-eye valve just below front of the deck, tucked in above the handle?

Mike

Last edited by Boulevardier; 29th Mar 2022 at 3:36 am.
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Old 29th Mar 2022, 6:48 am   #94
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Quote:
Originally Posted by ben View Post
Just stumbled across this, a 'Westminster' playmaster 4 track. Never seen one in the flesh, must be a fairly rare variant.
Was this also transistorised? The colour scheme looks similar to the transistorised Fidelity.
Westminster was a Curry's brand name. As far as I know this is a valved version and the colour scheme was not specific to one or the other. Hard to tell externally but the Fidelity models have a sticker on the back with the info - I don't know whether the badge-engineered ones did.

There is a non-working Transistorised PM on Ebay at the moment, with a black deck moulding - with a "buy it now" of £45.99 it will probably be there for a while.

Tony.
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Old 29th Mar 2022, 8:40 am   #95
david freeman
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

The Westminster designated Playmaster was definitely a bog standard valve model, made to be sold in Curry’s stores.
The transistorised model was never sold as a Westminster badged model.
The casing of both valved and transistorised Playmasters was identical apart from the colour scheme, and the addition of a “transistorised” badge on the deck plate.
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Old 29th Mar 2022, 9:04 am   #96
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Quote:
Originally Posted by david freeman View Post
The casing of both valved and transistorised Playmasters was identical apart from the colour scheme, and the addition of a “transistorised” badge on the deck plate.
Hmm, yes, but I think I have seen both valve and transistor models with the beige/cream cabinet, but only transistor ones with the black or grey top panel! Of course the badge is only self-adhesive so it can go missing.

More to the point, it would be interesting to know whether the later transistorised model had a revised circuit and whether it was any better.

Tony.

Last edited by Borderer; 29th Mar 2022 at 9:15 am.
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Old 29th Mar 2022, 10:08 am   #97
david freeman
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Yes, I’m waiting for this information, too!
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Old 5th May 2022, 9:03 am   #98
david freeman
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Did we get any further with the enigma of the Transistorised Playmaster’s lack of equalisation and abysmal technical performance?
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Old 23rd Jun 2022, 9:40 am   #99
Borderer
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

May I give this thread a bump?

I know several people are interested in this. Are we any closer to a schematic, or a solution?

I have just acquired another of these devices. Not looked at it yet, but it has a higher serial number than any others I have seen. So I am hoping that it is a revised version, if indeed such a thing exists.

Tony.
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Old 23rd Jun 2022, 9:49 am   #100
Ted Kendall
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

The long and the short of it is this :

There is no EQ in the playback mode.

There is an unused way on the rec/rep switch.

It's a bit awkward to apply NFB around the first two transistors as the volume control sits between them.

And there the matter rests for now, because other things pushed it aside, It should be possible to re-jig the amplifier without increasing component cost beyond the NFB network, which was the original term of reference.
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