cinema amps

[exurbia]

and another

[exurbia]

Many thanks to everyone who has replied to my query about these amps.

The beer midget (my lovely other half) has said either they go or she does. I told her how much i'd miss her and that i respected her decision.

What to do ??

[audiousername]

Originally posted by exurbia
The beer midget (my lovely other half) has said either they go or she does. I told her how much i'd miss her and that i respected her decision.

Originally posted by exurbia
What to do ??

Send this way for safe disposal! (the amps, not the wife )

But seriously, they look like they may really be worth saving. The big, heavy transformers alone indicate that they may well have been high quality amps in their day. Can nothing be done to dress them up to increase the spousal acceptance factor?

[exurbia]

the one i forgot.

[exurbia]

Spousal acceptance is not too difficult, she already lives with speaker baffles that are floor hungry. The amps may be worth saving but rejuvenating them is too time consuming for me. My original plan went something like this.

1 Find someone willing to do a rebuild/repair
2 Pay them for their services
3 Pay them either with money or kind ( i have a vast collection of valves etc,etc.

As we live in the nor west, freight cost would kill the transport of the whole lot.

Plan 2 is

1 find someone who can test and configure the output trafos then i could cajole my son into doing the rebuilds.

[EC8010]

That last photograph shows that the amplifiers were built quite nicely. They definitely need to be refurbished. I have eight NOS GEC KT66.

[audiousername]

It may be possible for you to determine the connections of the output transformer yourself.

Looking at the last picture you posted, pin 4 (the screen grid) on all valves is connected to the solder tag in the middle - this suggests they're configured in fixed screen mode, rather than ultralinear. The yellow wire on the left sockets, and the blue wire on the right sockets are the anodes of the valves, and these would be going to each end of the primary winding of the output transformer. The connection between the output transformer and the power supply will be the centre tap of the primary.

Determining the secondary connections won't be quite so easy. Sections of the transformer which measure <1W DCR with a multimeter are likely to be secondary connections. Applying a known AC voltage across the primary and measuring the resultant voltage across the secondary will allow measurement of the turns ratio, and the derivation of the impedance ratio as the square of the turns ratio.

Sorry I can't be more helpful, it's a little hard trying to explain these things in words.

[audiousername]

Oh, if you're just going to restore them like EC is suggesting, it shouldn't be necessary to get all the specifications for the OPTs since they should have been designed for that service.

[exurbia]

Thanks everyone



Restoring these t the original condition is not what i had in mind.

Plan 3

1 use the amps but set up for class a operation
2 put the chassis into a nice frame/plinth
3 listen
4 become a convert to valve power amps
5 stick with my HE setup

At the moment i use a valve pre with big big solid state amps the whole set up is active using a behringer ultradrive pro and 2496 ultracurve. The system has plenty of headroom as it uses pro audio drivers .

[audiousername]

It would have been nice to see them restored. Oh well.

Trying to describe how to redesign these amps is probably a bit much to try and explain on a forum. I could try, but I don't think I'd be very successful...

The ideal situation is where you'd be able to do it yourself after reading a book or two, but that's going to take up quite a bit of whatever spare time you have...

Hmm...