Mystery Valve Amp

[alternativeroute]

Just as a point of interest. Maybe all you Valve/Tube gurus can tell me;

If you look at the top picture in the first post. The yellow wire that runs across the top and terminates in a pig tail coil on the top right.

Would there be an electronic reason for the coiling of the wire?     

[Steerpike]

Would there be an electronic reason for the coiling of the wire?     

Too few trns for it to have any significant electrical effect except at MHz frequencies

[Steerpike]

I didn't want a second post - i wanted to append to the above: Anyway...

It seems to have too few turns for it to have any significant electrical effect except at MHz frequencies.

On a transistor amp there's often an inductor in series with the speaker for stability with capacitive loads - but that valve  output transformer is of such high indctance, a tiny coil like that is almost insignificant.

I see no selector for speaker impedance. Maybe that yellow wire can be moved to other transformer taps for other speaker loads.

Pye became a subsidiary of Royal Dutch Philips at some stage.

[Viagara]

In town there was an electronic repair shop owned by a "traditional afrikaner omie" - he referred to valves/tubes as "lampies".

Or as Johan(Ampdog) calls them "Buisversterkers" which I also think is very descriptive

[ghostinthemachine]

Looks like we have a snap!!!!
Thanks Mr GITM.
Standalone or built into a radiogram? What modern use could the amp have given that it is mono? A pure mono setup?

No problem 

Well, if you inspect the pic I posted of the cream PYE then you will notice that the one outlet is labeled "MOTOR" - which powered the turntable's motor of course. Would be dandy in a pure mono setup.

[Shonver]

Or as Johan(Ampdog) calls them "Buisversterkers" which I also think is very descriptive

... and a bit misleading, as I think it is meant to do equally well with midrange and treble.  

[Viagara]

... and a bit misleading, as I think it is meant to do equally well with midrange and treble.  

Ag nee man, Shaun! Nie "Bas" nie, "Buis!"

[Ampdog]

Jeepers, this is ruddy confusing.

They are (were) using a 'that era' mains socket for the loudspeaker feed!! (See Quad II and many others.) Then the JAN marking on components of those days were common. It stands for "Joint Army Navy" and mostly denoted war surplus components or components suitable for military use; a whole lot being available after WWII. The number after JAN is a military catalogue number, but I may be mistaken there.

Also, this amplifier has been refurbished some 20 years later, judging by the several brands of capacitors present. The blue electrolytics might be 'Daly", the yellow coupling caps were Philips, the green resistors also came from a later date. I do not think PYE would have done the coarse enlarging of the square output transformer hole; that transformer appears to be a replacement, although resembling the original. Lacking the chassis markings, might this possibly have been a privately built clone of a PYE? (Although identical internal tagstrips etc. are too much of a coincidence.)

The wiring was typical of upper class equipment of the day (see Leak, Quad, and others) before we were treated to the 'bundled' messes from the East.

.... and '78 rpm' on record players remained until much later. My Thorens 135 from 1970 still featured it, also including 16 rpm.

[Ampdog]

Correction - my eyes are up my .....

This is a home-made clone of the PYE shown, at least as far as chassis layout is concerned, and probably built in the UK. The screwed-together chassis is typical of what was available there, and most of the original resistors were available in the UK but not really over here - but someone else might correct me on this. As said, the variation in component brands suggests a later refurbishing, probably locally.

The circuit is readily traceable as a 6SL7 input stage (both triodes in parallel), capacitor-coupled to a 6SN7/6SL7 ltp (long-tailed pair or Schmitt), feeding output KT66s triode-connected. Most of the component values are evident from the clear underside picture; I found those to be commendable.

As said by others, to find a second equivalent is probably a no-go, unless someone wants one badly enough to have it built.

F_D, as an aside, my amplifiers usually have 10-0-220-240V power transformers, seeing as how practical mains voltages can vary over the country. (... and vary over 24 hours in some places, in which case such an arrangement is useless).