Loctal Single Ended Amp

[TomMcNally]

I built this over the last two evenings. It's a single ended Loctal amp, using 7C5's which are functionally equivalent to 6V6's and a 7F7, which works like a 6SL7. The circuit is pretty simple, kind of like a Clementine. I used an Edcor XPWR106 and a pair of diodes and a Hammond 156R choke in the power supply. The outputs are Edcor GXSE15-16-10K which act like 5K transformers with 8 ohm speakers. The pinout of the 7F7 is symmetrical, which makes for a nice neat build.
Sounds pretty nice, I played one CD before I fell asleep, didn't crank loud yet though.

[DeathRex]

I thought you would get hum if you have the power transformer oriented the same as the output transformers?

I wish Edcor would have a cover so you can mount the power transformer horizontal.

[TomMcNally]

I actually mounted the transformer that way accidently, and was relieved when there was no hum. Holes are hard to un-drill! There is a pretty good air gap between the PT and OPT's, so that must help.

[Geek]

I wish Edcor would have a cover so you can mount the power transformer horizontal.

They've had quite a few requests for a "Z"-mount, but aparently the endbell costs are phenomenal (maybe Brian has to buy a million at a time?)

Cheers!

[Hotsauce]

It would make too much sense if trafo mfg used square pattern of mounting holes, so we could turn them.

John

[EWBrown]

Very nice design and build, Tom... I'll have to extricate my loctals from the tube stash and put them to some gainful purpose.
I sold off all of the "radio" type (pentodes, etc) loctals last year, but I did keep all of the useful audio tubes for future projects.

/ed B in NC

[rock4016]

I used these vertical end bells on my Edcor GXSE transformers and they worked great.
http://www.ebay.com/itm/EI87-Transforme ... 233439e798

[vvelt]

Nice job, Tom. Your wiring is so clear I can visualize this even though I'm a relative newbie. Triode strapped with split supply rails to the driver? Do you have a parts list/schematic for this?

[TomMcNally]

I looked around for the schematic I used, but didn't find it. Basically, any Single Ended 6V6/6SL7 circuit with the pin numbers swapped for the Loctal equivalents will work just fine. You could go with a tube rectifier if you can find a Loctal version (and a spare!) This is a pretty simple circuit, and it sounds real nice. Sockets are available from various tube dealers or on eBay.

... tom