Help selecting a DIY schematic

[bamadawg]

Hello All...

I have recently gotten into DIY tubes, working on some older EICO gear. I have to admit, I am not an expert by no means. I have a vintage HH Scott LK72 (kit) integrated - and was interested in using the iron off it to do another DIY integrated amp with.

The amp has 1 power tranny and 2 output trannys. I am not sure where to look to get the specs for these, as I am sure their specs will determine the tubes it can drive. It is rated @ 35wpc.

I would like like recommendations on some published schematics to build a integrated on a new chassis - like the Hammond chassis'. I am very interested in using the 6sn7 preamp tubes - like was used in some of the Williamson amps. I am not sure what power-tubes are candidates for the iron I have. Any help on tracking down the specs for the trannys I have (power + output) would be very greatful. I would like something rather simple, as I am rather new at this. I do not need a phono-section - if that helps narrow it down any.

I am open to any suggestions - I am jus not sure what this iron is best suited to drive that is rather simple to build with tubes that are relatively easy to roll.

Any is help is greaty accepted.

Nate

[tubelab.com]

If I remember correctly the LH72 used EL-34's it was a pretty good amp, and might be worth rebuilding if it is in good shape. If you are determined to use the iron to build your own, there are zillions of EL-34 schematics on the net that make about 35 watts per channel. Pick one that fits your needs that uses parts or tubes that you have, or want to use.

[navin]

Originally posted by bamadawg

I am very interested in using the 6sn7 preamp tubes - like was used in some of the Williamson amps.

There are atleast a few ckts using 6SL7 and 6SN7 out there on the net.

Steve Bench has a triode 6SL7-EL34 ckt on his website, Wayne has posted a ckt that uses a 6SL7 and 2 6SN7 for stereo EL34 amp, Raymoth and Sy have posted full diffrential ckts that use 2 6SL7 and 2 SN7 per stereo amp.

see this thread. it might help...

EL34 schematic confusion

[bamadawg]

These are the tubes the LK72 use:

(4) 12AX7
(2) 7199
(Split-load phase inverter)
(4) 7591
(1)5AR4/GZ34

Nate

[Eli Duttman]

Scott LK72B schematic here. The LK72B uses 7591s as the "finals". IMO, there are no good reasons for using the O/P "iron" with any other type.

Scott, like Fisher, used a discrete winding for a negative supply that biases the "finals" and powers 12AX7 heaters. The bridge rectified supply in the LK72B is approx. 50 V. If you use a voltage doubler instead of a bridge, there are plenty of Volts available for series regulated bias and CCSes in the tails of differential phase splitters.

Take a look at dhaen's PP 7591 thread. A fair amount of that project is relevant, although the Scott power trafo will have to be paired with a cap. I/P PSU filter. There are all sorts of nice 12AT7s that can be "rolled".