Hi guys,

I have come by a combined Radio/Amplifier which was manufactured by Classic Radio Sydney (which I believe used to be on Parramatta Road at Haberfield). It is a steel cased unit powder coated brown gold colour.

The unit doesn't have a model number unfortunately but on the front dial it has the wording 'Stereophon'.

The valve lineup that was in it when I got hold of it are 6BM8s (x4); 6N8 (x1); 12AU7A (x1); 6AN7A (x1); EM840 (x1)

I have scoured the net to find a schematic for it but nothing available that I can find.

Any assistance would be appreciated.

Cheers,
Bluedoggie

That company produced amplifier kits based on designs that were published in Radio Television & Hobbies and Electronics Australia.

The schematic you're after may well be in one of those publications.

To try to narrow things down, see if you can find any date evidence on the components. Capacitors often had year of manufacture coded on them. Transformers, too.

A good front-on photo may also be helpful. Send to Brad: https://vintage-radio.com.au/default.asp?id=image-submission-guidelines

Thanks for that GTC.......I figured it for early 60's looking at the style and the transformer is stamped April 1959 which supports that age. I will send some photos to Brad to post with this thread and hopefully someone might have a diagram for it.

I have already recapped it based on what was under the hood but just wanted to go through the circuit and double check all the values because I can see there have been many replacement parts and repairs made before I got hold of it.

GTC is right. These Classic Stereophon units are based on the Radio Television & Hobbies Playmaster series.

Going by the valve line-up it should be from the early 1960's. The later Stereophon's used 6GW8's for output valves. Myself or someone here should be able to easily find a schematic & possibly even an advertisement from the RTV&H

On the subject of Classic Radio here is something I posted on this site last year:

"Contrary to information on other vintage radio sites, there is no connection between Classic Radio (& TV) Pty., Ltd. of Melbourne and
Classic Radio Service of 245 Parramatta Rd., Haberfield, Sydney. Classic Radio (& TV) Pty., Ltd. did have a Sydney branch at 125 Botany Rd., Waterloo between 1949 & 1960."

Thanks Mono, I 'assumed' that Classic Radio that were in Malvern and the Haberfield Classic Radio were the same company!

I have sent Brad some images of the unit so hopefully will get posted to this thread at some stage.

Much appreciated if someone could help with the schematic for it.

I'm inclined to think it may be a relative of the 7 valve Playmaster 106 Tuner-Amp from RT&H December 1963.

Lineup: 4 x 6GW8, 12AU7, 6BA6, 6AE8 + semiconductor diode detector.

I checked that Playmaster 106 on the Radio Museum site and visually my amp is identical to the picture on that site and valves are the same except they have used the 6GW8s rather than the 6BM8s.......thanks heaps GTC.

Externally that series of Playmaster tuner/amps were similar, as designed by RT&H staff.

Your lineup, as stated, is 8 valves including a 6N8 (duo-diode + pentode for IF amplifier / detector / AGC), so it does not appear to be exactly the same model as the Playmaster 106 as published in RT&H, hence my saying it looks to be a 'relative' of the 106.

Photos uploaded.

I think we need go back a bit earlier than 1963. I reckon more like 1960 or 1961.

Are the output transformers ultra-linear & does the power supply use a voltage-doubler?

I've got something that looks like that... but it doesn't have any labels. It does have the same knobs though. I think the station dial is missing.

I'll dig it out and open it up next Wednesday and see what's inside.


It used to live in the garage here, connected to a Southern Cross (aka Dick Smith) FM tuner, and stereo speakers. About 6 months ago it was retired, still in working condition. Never needed to open it.

Thanks for the photos. Although the front panel of yours is quite similar to the Playmaster 106, it's not exactly the same. The selector switch on yours is leftmost position whereas the RT&H one has the selector switch second from right.

Monochrome has made mention of the 6GW8 which came into being circa April 1961. Prior to that RT&H used the 6BM8. RT&H started to use the 6GW8 in preference to the 6BM8 in their 3-valve Playmaster 3 of January 1962.

I am getting the impression that your tuner/amp may be some sort of Playmaster hybrid created by Classic Radio around 1960/1961.

RT&H produced their first Playmaster tuner-amp (the Playmaster 106) by adding a 2 valve AM tuner onto an existing Playmaster amp design, the Playmaster 4.

The Playmaster 106, and the Playmaster 4 have ultralinear outputs. It would be helpful to know the model number/code on your output transformers.

I'm thinking that you've may have a Playmaster 2 of August 1960 (4 x 6BM8) and a bespoke tuner.

I'm thinking that you've may have a Playmaster 2 of August 1960 (4 x 6BM8) and a bespoke tuner

I'm thinking you are correct. Here is the advertisement from RTV&H, December 1961.

Playmaster Unit Stereo Amplifier Circuit Diagram

Thanks for posting the photos Brad and also the responses GTC, Mono and Robbert.

Just away for the easter weekend now but will post some more specifics about the unit next week.

Thanks for the circuit Mono, that is it exactly and my unit does have the ultra-linear output transformers and the power supply uses the twin diode voltage-doubler arrangement.

Interestingly the RT&H article included with the circuit talks about the 'extra cost of using silicon diodes which should provide unlimited life' (as opposed to the standard valve rectification)! It's easy to forget that something as simple as a diode which we take for granted now was cutting edge back then.

Anyway, I look forward to giving this old unit a new lease on life and will post some photos and words once complete.

Thanks again to you and GTC and others with assistance with this, it is very much appreciated.