Playmaster Sixty-Sixty Stereo Amplifier SCHEMATIC

[glennb]

Playmaster Twin 25

Someone asked for Electronics Australia magazine articles on the Playmaster Twin 25 pre/power amplifier, the predecessor of the Playmaster 40-40 of 1976/77 and Playmaster 60-60 of 1986, so here they are:

http://dl.dropbox.com/u/44941643/Playmaster-Twin-25-v1.pdf
8.15 MB, 24 pages, scanned at 150 DPI, 256 greyscale
Copyright Federal Publishing 1976
Reproduced for the purposes of fair research non-commercial use

I built one of these from the Dick Smith kit when I was 17. It ran at maximum volume for hours at parties and never had any problems, although the rear panel was very hot.

 

[Ian Finch]

Thanks Glenn; a great addition to the record of Oz 2N3055 Quasi amplifiers. 'Just adding a comment that the 40-40 was a later revision (1977?) of this amplifier design with a larger transformer and higher power rails of 36V, IIRC. Both were cheap and I built several kits up for friends wanting amplifiers at the time, but I don't recall them as sounding anything special - just OK.

In comparison, the 60-60 had a "balanced VAS" design and 50V rails inspired by the earlier Hitachi power MOSFET application notes. It had higher rated complementary MJ15003/4 output transistors too. An early "Symasym" topology, in effect.

 

[masood]

dear all,
can any one send me the pcb image of twin twenty five amplifier hankst

 

[Ian Finch]

Hi Masood
I don't have artwork for those very old designs but you should be aware of the size of
Playmaster twin 25, 40/40 and 60/60 designs. They were integrated amplifiers. Their PCBs were quite large and laid out to include phono preamp. plus volume, balance and tone control circuits, in the basic style of ~ 40 years ago, using discrete, TL071 or later, NE5534A/AN OP-amps. The 60/60 for example, was a full rack case size, 42 x 24cm PCB IIRC, The others, about half the area but still substantial. Look at the pic. of the EA mosfet amp in Tiefbassuebertr's earlier post. That is the smallest board used by EA at the time.

If you are only seeking amplifier PCB designs, it would be better to do your own. Given the countless PCB designs you have been collecting on DIYaudio, this should be very simple for you and easy to improve on the originals at the same time.

 

[masood]

Hi Masood
I don't have artwork for those very old designs but you should be aware of the size of
Playmaster twin 25, 40/40 and 60/60 designs. They were integrated amplifiers. Their PCBs were quite large and laid out to include phono preamp. plus volume, balance and tone control circuits, in the basic style of ~ 40 years ago, using discrete, TL071 or later, NE5534A/AN OP-amps. The 60/60 for example, was a full rack case size, 42 x 24cm PCB IIRC, The others, about half the area but still substantial. Look at the pic. of the EA mosfet amp in Tiefbassuebertr's earlier post. That is the smallest board used by EA at the time.

If you are only seeking amplifier PCB designs, it would be better to do your own. Given the countless PCB designs you have been collecting on DIYaudio, this should be very simple for you and easy to improve on the originals at the same time.

dear thanks

 

[masood]

Here is the P.C.b. design i modified for playmaster 300 watts,Since 80's I am using them till date,4nos. 15" speaker per channel and never failed me

dear ved mitra ji,
plz.send me its circuit details .thanking u yours ever masood

 

[tekboy]

I love the internet!

Hi guys. I have a Playmaster 60/60 that I built in about 1987. I recently got it out of the garage in order to hook up my old Thorens TD165 to trouble shoot a problem. I went looking for info on the web and came across this thread (yay internet!).

I found that the amp was making a huge amount of hash/noise when I powered it up. Then I recalled that the reason I put it away in the first place was that I had repeated failures with the NE5534AN op amps.

Initially I thought they might have damaged in the process of soldering them to the pcb, so I put sockets in all around. This did seem to solve the problem but the amp was still seemed to be prone to destroying the NE5534s. Is this something that anyone has come across before or could it be a fault with my amp? It seems that the op amps in the line level preamp and tone control circuit are the most prone to this issue, while the phono stage seems pretty bomb proof.

Thanks glennb for the EA scan, this will make any trouble shooting much easier!

By the way, my amp was a 'blueprint special edition' which means it has 1% metal film resistors, polyethylene and polyester caps, uprated philips output caps and an uprated transformer (raising output to around 70 watts into 8 ohms stereo I believe) and a swanky special edition silk screened front panel!

Anyway, I always thought the old girl sounded pretty good with my Thorens and a pair of Kef speakers.

Thanks for the great thread and keep up the good work!

 

[Kenroy]

Hi glennb,
I'm Ken's son Graham doing some research for him on the Playmaster 60/60 "Blue Print limited edition" stereo amplifier. He says the tone circuits may have a fault and needs the schematics to fix it.
He's just turned 89 and would love to get this baby up and running again! He built bass speaker enclosures from a "folded horn" design and crafted mid-range horns from "Pinex" (chipboard!) in the late 80's. I can supply photos if you're interested.
We all remember the power it had! Gosh!!! The first time we heard "Time" from Pink Floyds "Dark Side of the Moon" cranked up was absolutely breath taking!
Anyway... I tried your dropbox link and its broken. Dad still has ALL his magazines and if I had the Issue and/or Volume reference, I'm sure I could find it!
We would appreciate your help.
Graham and Ken

 

[wintermute]

Was the "blue print edition" a re-do of the original design? I have the original schematic and have taken a photo of the preamp section if it is of help. It was in the June 1986 edition (part 2 of the article)

Since this is for a repair and this is only a partial of the full schematic I have attached.

Tony.

 

[Old'n'Cranky]

Pretty sure the blue print versions were jaycar/altronics 'premium' versions that had the new fangled metal film resistors, r core transformers, and better caps in certain spots.

 

[Ian Finch]

...new fangled metal film resistors...

Yes, Jaycar actually produced "blueprint" versions of a few EA and ETI magazine designs in the 1980s. The difference between these and standard versions of the 60-60 began as you say, in the supply of all 1/2W metal film resistors in lieu of 1/4W 5% carbon film types and the power supply caps which were Philips types - still working in my own amp, surprisingly.

I believe that the RIAA phono preamp resistors were also MF in the standard version which was supplied by a number of competing kit sellers. Other differences were in the supply of 'A' suffix opamps (guaranteed noise spec. versions of NE3334) which were otherwise skimped on to save a dollar, at the time. Oh yes, a thin blue surrounding line was also added to the front panel artwork. It looked OK if you then trimmed off the rack case ears to normal case dimensions for home use.

The transformer in blueprinted and also some standard kits, was a locally built "C core" type by Jones Transformers in Melbourne, I think. It was poorly assembled, had a strong enough stray magnetic field to cause the cover to sound like a screwdriver dropped on it when switched on and the bobbin required packing with shims to stop the vibrational hum/buzz on the several examples I either built or repaired over many years. I suspect that a standard EI type would have been a better choice, had there been a higher VA rated 35 +35VAC type available. Being imports, suitable toroids weren't competitive at the time.

A feature of the design is the simultaneous increase in dynamic range for transients and the SOA protection afforded by its poor transformer regulation. A stiff power supply would have meant SOA problems and this "sagging" supply rails technique was also exploited in a lot of Japanese products at the time. I think though, when a few niggles were ironed out of typical DIY kit builds, this probably stands as EA's best Hi-Fi production - noting its unusually good phono preamp, for the time.