** German products once used an odd IEC like connector with two pins and
ground via the casing.
Interesting, could be that they were German imports since Im in Sweden. Or they picked up the same specs here. All I know is that they were at least not used in broadcasting studios since they would have had a special cutout part of the chassis then.
Same panel cut out I think, see them on old "Dynacord" amps and " Echolette"
tape units from the 1960s.
And Leitz Focomat photo enlargers from the 60's
Im in two minds about the Jones connector.
On one hand it looks retro funky.
** Huh ? Looks appalling to me.
The think is, the Jones plug does not look hifi at all, just sort of vintage industrial. I think it fits to the general design of the Quads. But I thought of changing it to a phono anyway to make it more usable for future users (and yes I hope these amps will last another 50 years)...
The only giveaway that the amps have been modified is that I placed AC
switches where the fuse holders were. But they are old British chromed
switches and look contemporary. The fuses are now inside the enclosures.
** You have just given me an idea....
.... Phil
Old Bulgin switches have nicely ribbed chrome rings. But I have seen different fuse hole sizes in Quads. Im mine they fit precisely.
To conclude, I did finally find some 5V4GA and those behave very much like GZ32. Dropped the B+ voltage back to around 360v and this seems to work well. Great sound. The transformers and choke get warm but not hot.
I am still trying to find out why Peter Walker's drawings say 340v. Perhaps this was measured with the original QCII preamp drawing current. I dont have one of those (yet).
For other readers coming by, I can try to sum up my Quad II rectifier experiences so far:
5AR4/GZ34 are great but can result in excessive voltage! Do measure your amps if you are running these. I had around 385v at the first cap, which could be bad in longtime use depending on ones tubes, caps and resistors. They need just 1.9A heater current which is good, though. I had installed new computer grade caps of 33uF and 47uF @ 450v which may have given different results than using the original TCC 16uF caps in the grey box.
GZ32 and 5V4G/GA seem to make it just right at 360v. Especially 5V4 has a 2..0A heater which is better than GZ32. Indirectly heated. The closest approach to the original specs
5R4GYA is a directly heated rectifier, and the B+ voltage comes on instantly and can peak at over 400V. Was not a problem for me, no arcing or anything, but I dont think the output tubes will like such treatment forever. Best would be to have standby switch. B+ after warmup became 340v just as in the original drawings. This tube also has a 2.0A heater and worked well otherwise. The coolest running Quad II rectifier combination: My amps did not get very hot even after hours of use.
I almost accidentally tried a 5U4G at first, until I checked my old RCA manual. 3A heater! Using this in a Quad would NOT be good for the transformer.
Also note that I was only using vintage tubes. I dont know how the new Chinese or Russian ones will behave.
I hope I got all the numbers right.
/Martin