Need info on Knight Model 30-B Tube Amp

[bluesman]

I just picked up a Knight Model 30-B Tube Amplifier on eBay. It is a PA/Phono amplifier that uses (1)5Z3, (2) 6L6, (2) SN7, and (2) 6J7. I have not been able to find a schematic anywhere. Does anyone have any info on this amp? It looks to be in pretty good shape, and I plan to try to get it working as my first amp project for guitar and/or harp.

This is the item:
http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA:IT&ih=005

Thanks!

Tom Muck

[J Martin]

That looks pretty clean and simple inside. You can probably work on it without a schematic. I think those tubes are 6N7 not SN7. I rebuilt an old amp a few years ago with the same tube line up. It sounded really good. My customer used it for everything and its on almost every track on his CD.

[bluesman]

Yes, it is pretty clean. I was going to recap it, but there is one electrolytic can that has been replaced already. I was hoping to check a schematic to make sure this was a correct substitution -- I'm new at this, and the substitution looks suspect. :-)

Also, there are two leads clipped off. I'm 99% sure they go to the pilot light that was removed. Other than that, I can proceed and give it a try.

Tom Muck

[J Martin]

The cap value isn't critical. Often when replacing can caps, I'll use the newer JJ cans. Maybe a 32/32 for the plate and screen nodes and a couple of 20uf axials down the line. No need to load it up with a whole lot of filter capacitance in my experiance.

As far as renewing tubes there are options. If you want to get rid of the grid caps on the 6J7 tubes the socket can be rewired for a 6SJ7. You can rewire the 6N7 sockets for 6SN7 or with socket adapter, a 6CG7, 12BH7, or 12AU7. For the 6L6 tubes the new Tung Sol 6L6G would sound good and look like a tube from the time the amp was made. The 5Z3 is the same as a 5U4 except for the pin out. Use the online tube manuals!

[bluesman]

Thanks, that is good information. I'm a newbie at this, so I think I'll start with recapping and see how it goes and see how it sounds, if at all.

I also picked up a Heathkit A7 that I had planned to do the same thing with, but the darn thing sounds great as is. A recapping may be in order, though.

Tom Muck