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Playmaster amplifier - an update and thank you....

coylum

coylum

Well-Known Member
I have recently completed the rebuild of a Playmaster Twin 10 Stereo amplifier and Playmaster Control Unit no 10 - both of Australian design (John Moyle) from 1959 and 1960.

Over the last couple of months I have had help from many on this forum, particularly in respect of NFB adjustment and other matters.

The links below are a pictorial record of the renovation and may be of interest:

Playmaster Twin 10 Amplifier: http://imgur.com/a/W9LfK
Playmaster Control Unit No10: http://imgur.com/a/ctuEo


Thanks again
 
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Very nice resto job! where did you get the new labels for the trannies?
You can't beat those old transformers, outstanding quality in those.
 
primosounds said:
Very nice resto job! where did you get the new labels for the trannies?
You can't beat those old transformers, outstanding quality in those.
Click to expand...

Sorry for the late response but I have only just seen this! The transformer labels were made by photographing the original damaged labels, repairing them in Paint and then printing them with an inkjet printer onto white water slide transfer paper. They were cut to shape before application so as not to show the white substrate.

Thank you for your comments
 
Amazing job and attention to detail!

What type/brand of spray paint did you use? I've been searching for a copper color like that. Did you clear coat it?
 
Beautiful work! Interesting that you restored the preamp too. Many preamps from that era are written off sonically, even after restoration. Are you happy with yours?
 
Dandy said:
Beautiful work! Interesting that you restored the preamp too. Many preamps from that era are written off sonically, even after restoration. Are you happy with yours?
Click to expand...

This is the first preamp that I have renovated and I do admit to being a little disappointed - definitely the amplifier performance was better sonically than the combination. I think there are inherent limitations in valve preamplifiers paricularly when looking for high gain for MM cartridges; noise is certainly an issue.... and I think distortion is way higher than an equivalent solid state preamp.

I have tried using the preamp stages of a Leak Stereo 30 Plus (solid state) as the preamp and the result is far improved over the Playmaster preamp

Cheers,
 
Thanks for the reply coylum. What you report is not unusual for tube preamps of that period. But yours is still a beautiful rebuild.
 
Very nice work indeed.

Personally I suspect a lot of "blah" preamp performance is just the tone circuits in use. Those passive controls have a lot of loss, and I suspect they probably have a fair bit of phase shift going on. Checking the phasing might be an interesting test if you can do that. Frequency response looks pretty good but that doesn't always tell the whole story.

The Mullard 5-10 style amps I own had absolutely terrible tone circuits in them. Instead of bass and treble I got "head in a box" and "screeching ear bleed" controls. Making them not sound awful involved bypassing them, and then triode-strapping the EF86 to drop the gain down to sane levels. The stock 5-10 front end is basically from the second EF86 onward in your preamp fed straight into the 12AX7 of the power amp. Triode strapping the EF86 and bypassing the tone controls gives me something a whole lot closer to just your power amp now. I've been meaning to revisit those and try official Mullard 5-10 tone control circuit values to see if it helps any, but its on the long term list.
 
I have the Verdik preamps, based like their power amps, on the Mullard circuit. These mono pres use two EF86s. I've not bothered to rebuild them, though I sometimes wonder about it just for conservation sake. The power amps sound fantastic without the pres, and I don't see a reason to downgrade from nearly perfect (I have triode strapped the EF86) to dull.

For CDs, I bet the power amp sounds great with just a pot. BTW, I really like your diy 'can' caps. So elegant.
 
gadget73 said:
Very nice work indeed.

Personally I suspect a lot of "blah" preamp performance is just the tone circuits in use. Those passive controls have a lot of loss, and I suspect they probably have a fair bit of phase shift going on. Checking the phasing might be an interesting test if you can do that. Frequency response looks pretty good but that doesn't always tell the whole story.

The Mullard 5-10 style amps I own had absolutely terrible tone circuits in them. Instead of bass and treble I got "head in a box" and "screeching ear bleed" controls. Making them not sound awful involved bypassing them, and then triode-strapping the EF86 to drop the gain down to sane levels. The stock 5-10 front end is basically from the second EF86 onward in your preamp fed straight into the 12AX7 of the power amp. Triode strapping the EF86 and bypassing the tone controls gives me something a whole lot closer to just your power amp now. I've been meaning to revisit those and try official Mullard 5-10 tone control circuit values to see if it helps any, but its on the long term list.
Click to expand...

I renovated two Mullard 5-10's (Aegis brand) without tone controls and they perform superbly. They are fed usually from a cd player but I also have the facility to feed them via a Leak Stereo 30 preamp section when I require phono sensitivity and this is also a good combination. My Mullards EF86's are wired as pentodes and I just lower the sensitivity via a resistor network.

Cheers, Malcolm
 
Dandy said:
I have the Verdik preamps, based like their power amps, on the Mullard circuit. These mono pres use two EF86s. I've not bothered to rebuild them, though I sometimes wonder about it just for conservation sake. The power amps sound fantastic without the pres, and I don't see a reason to downgrade from nearly perfect (I have triode strapped the EF86) to dull.

For CDs, I bet the power amp sounds great with just a pot. BTW, I really like your diy 'can' caps. So elegant.
Click to expand...

I agree that the Mullard 5-10's sound great connected directly to CD - I haven't triode strapped the EF86's - just a divider network.
My DIY caps worked out really well and I will use this in future renovations - so simple and much easier than trying to re-stuff old cans!

Cheers, Malcolm
 
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