GK-71 amp in triode mode.

[pre65]

This is my latest amp project, a Russian GK-71 connected as a triode.

The driver valve is a 12GN7 (12HG7a) with a DC heater supply and a CCS on top (Ixys 10M45s) as I was out of stock of anode chokes.

The PSU has a single mains transformer and hybrid bridge with 6D22s valves. After that it splits into two with choke input and a Mike Holmes "E-choke" per channel.

Sounds pretty good at the moment, a bit better than my old GM-70 amp if memory is anything to go by.

[pre65]

The anode connection was by croc clip, not very professional.

So this morning, I've adapted some 832a type anode connectors and they are now in place.

[Richard]

Neat, they also look like NGK plug caps Is this your regular amp now Philip or do you swap around, you must have so many or do you break them down to try new ones?

[pre65]

At the moment I'm using my KT66 (as a triode) monoblocks. They also double up as driving amps for the mighty 833a TV trolley monoblocks.

The GK-71 will be my regular amp soon. When it was on the floor it was very good, but on putting it all on a rack (for domestic reasons ) I gained some hum, which has yet to be sorted.

Yes, amps come and go, very good ones are kept, others recycled into the parts centre for future projects.

[pre65]

I've been converting the amp PSU for the last six months.

The new supply is dual mono (like the amps), and will be too big to put on a rack, so hopefully the hum problem will vanish.

The existing amps will sit atop each PSU, so will take up less floor space.

[bob orbell]

Always like reading and seeing your lash-ups, sorry, projects Philip, lets have some more pictures of the power supply's. BOB

[Richard]

Me too form follows function eh

[pre65]

Here is one from last week. I'll post a later one showing the white finish and bun feet later.

[pre65]

The mains transformer (360-0-360), and the diode plate were removed from the 833a amp, which is in the queue for upgraded transformers.

The rectifier is a hybrid bridge using two 6D22s damper diodes and the said diode plate.

I was hoping to have a good few hours work on these today but I now have a bowls match this afternoon.

When I've sorted out how the main amps will sit on the PSU I'll post a picture.

[pre65]

Got them both back into action this afternoon.