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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 23rd Jun 2022, 11:01 am   #101
Boulevardier
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Don't know if anyone has checked, but I wonder if there was any recording-mode equalisation used. Perhaps there was no equalisation for either mode. Maybe Tutchings covered this.
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Old 23rd Jun 2022, 1:16 pm   #102
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

The very concise review is in here. https://worldradiohistory.com/Archiv...nd-1966-08.pdf
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Old 23rd Jun 2022, 8:02 pm   #103
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Obviously a lot of interest going by the high number of Thread views, I find it interesting.

David
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Old 24th Jun 2022, 2:43 pm   #104
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

My new example is in better condition than the last one, clean and unmolested inside and seems substantially original. At first glance there are minor differences in the PCB, but will have to compare it carefully with earlier photos. It has HT, mains hum through the speaker, but no audio, so we will see.

Will upload some pictures asap.

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Old 24th Jun 2022, 4:55 pm   #105
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Photos attached
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Old 24th Jun 2022, 6:24 pm   #106
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Mine had a dead output stage, not even hum. Maybe next month I will take another look. Will upload pics for comparison.
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Old 24th Jun 2022, 7:53 pm   #107
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Looks the same to me. Does it have a spare way on the rec/rep switch? Random thought - did the transistor machine precede the valve version? It could just be that, faced with an intractable problem, Fidelity just "ran home to Mama" and used valves instead, After all, the later Braemar did, didn't it?
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Old 24th Jun 2022, 8:36 pm   #108
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Quote:
Originally Posted by Ted Kendall View Post
Looks the same to me. Does it have a spare way on the rec/rep switch? Random thought - did the transistor machine precede the valve version? It could just be that, faced with an intractable problem, Fidelity just "ran home to Mama" and used valves instead, After all, the later Braemar did, didn't it?
There is a spare position on the r/p switch. Haven't studied it all properly yet.

AFAIK the valve version came first in about 1964 and continued after the transistor one was dropped, then as you say the Braemar used valves. They do seem to have got cold feet about transistors although there was another model - Playmatic? which was a transistor/valve hybrid.
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Old 24th Jun 2022, 9:46 pm   #109
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

I still have my original TR5 (valve) version, and limitations of the transistor type shown
must surely be down to the early design - although Philips were making an all transistor
design by this time. Moving forward a few years a fully transistor design (based on a
Mullard circuit) used only 6 transistors e.g see p44 of this PW tape recorder project;

https://worldradiohistory.com/UK/Pra...PW-1971-12.pdf
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Old 24th Jun 2022, 9:47 pm   #110
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Given that the follow-up to the Tutchings review didn't appear and that other transistor examples don't differ much, if at all, I think Fidelity just gave it up as a bad job. Which isn't to say that it can't be improved, but the topology is awkward.
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Old 24th Jun 2022, 9:49 pm   #111
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Quote:
Originally Posted by Restoration73 View Post
I still have my original TR5 (valve) version, and limitations of the transistor type shown
must surely be down to the early design - although Philips were making an all transistor
design by this time.
Undoubtedly the components and knowledge existed, just not at Fidelity.
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Old 24th Jun 2022, 9:57 pm   #112
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

The footnote to the Tutchings review may perhaps have just been a bit of editorial diplomacy. I guess in production terms a revision would have meant a new pcb and it may not have been economic. But it doesn't explain how they got it so wrong in the first place.
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Old 24th Jun 2022, 10:35 pm   #113
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Quote:
Originally Posted by Borderer View Post
But it doesn't explain how they got it so wrong in the first place.

Nor why, given that they must have known it was rubbish, they let it out onto the market under the Fidelity brand name. That's what I find really baffling. Suggests a catastrophic breakdown in design, product development, and quality control systems.


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Old 24th Jun 2022, 11:00 pm   #114
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Depends on what you mean by "rubbish" - perhaps they thought they could get away with it at that price point, although the earlier Argylls and such were decent enough budget machines. Maybe it was the work of some bright young thing who left before he finished the design - who knows, after all this time?
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Old 24th Jun 2022, 11:02 pm   #115
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

Sometimes an external influence means you are forced down a path you know to be a problematic

Back in the early 90's we developed a product where HQ wanted to use a particular architecture. The engineering team thought the technology immature, and so it proved. It was a disaster, sales fell off a cliff and it put us on the back foot to replace it after a year where as typical product cycle was between 8 and 10 years.
The problems were immediate and at that time unsolvable with the existing hardware.
Our current products use very similar architecture but developed 15 years later when it was mature.

It did a lot of damage to our reputation.

The same may have been true at Fidelity.

The salesman all wanted to bandy around the title "transistor" when the development team had insufficient expertise and resource to succeed.

Such things are happening somewhere even now.

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Old 25th Jun 2022, 5:27 am   #116
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Default Re: Fidelity transistorised Playmaster - reverse engineering?

The situation may well have been something like Mike T describes.

The PW design referenced in post 173 makes interesting reading, to me at least, and I wonder how it would compare with the Fidelity in practice.
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