Mystery stereo valve amp and pre...

[spendorman]

Whilst it's irrelevant..... I have I believe identified them as kit amplifiers made to Mullard designs by Stern Radio Ltd around 1962.

Excellent, I remember Stern, then presumably later Stern-Clyne

[ff1d1l]

What is the name under the treble knob? Can't read it all because of the angle of the photograph.

Its "Dual Stereo"

Stern...excellent...any Pics anywhere, Jez?

Thanks all!

[Arkless Electronics]

Its "Dual Stereo"

Stern...excellent...any Pics anywhere, Jez?

Thanks all!

From an ad in a 1962 Practical Wireless. Pics are tiny, blurry and B&W but it appears to be the same as the control layout and positions of the 1/4" jacks on the front panel are the same. The power amp is as I guessed and the pre is two of the Mullard "Two valve pre amp" design, for stereo. if correct it would have had 2X EF86 per channel.

[BTH K10A]

..

[ff1d1l]

It would be a Stern Radio Ltd Dual 3 - 3 stereo amplifier then, with the 4 valve dual channel control unit which should contain 4 EF86 valves.

Both Mullard circuit designs

The input sensitivities are:
Aux 330mV
Mic 3mV
Pickup 5-15mV &70-220mV
Tape 4mV
Radio 330nV

Amp is obviously 3 Watts per channel with the single ended EL84
Frequency Response is 35 to 30kHz

Absolutely without a doubt. Just googled, and although the exact ringer for the power amp isn't there, the mono version is same gold chassis and same trafos with the same voltage selector on top. Well, now I know - thanks very much to everyone. If and when I get it going - probably the power rather than the pre - I'll report back. Cheers again guys!

[Barry]

Design and construction of the Mullard 3-3 amplifier: http://www.r-type.org/articles/art-003h.htm.

The 3-3 was a mediocre-sounding circuit and nowhere near as good as the later 5-10 and 5-20 designs.

[Firebottle]

If and when I get it going.....

When I rebuilt the Dulci into a stereo single ended amp I used the following driver stage circuit, with very good results as Martin will confirm.



Use a medium mu valve such as the ECC81 and don't forget the heater bias (2 resistors at the right).

Just a suggestion

[BTH K10A]

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[Macca]

When I rebuilt the Dulci into a stereo single ended amp I used the following driver stage circuit, with very good results as Martin will confirm.

[

I do confirm. One of the most beautiful sounding amplifiers I have ever heard. A bit limited on power which is the only reason it is not my daily driver (big room) but that is the nature of the beast.