Old Kay tube amp

Rsolinski · Guest

Hi all,
I am new to this forum and I have a question..I recently purchased an old Kay model 703 tube amp (GREAT tone) and I would like to use some different speakers with it (the alnico 6 is okay but breaks up a little)...The leads to the speaker are connected to a transformer that is mounted on the speaker? Can I connect some other speakers? I have never seen this configuration before...thanks!

Ray

TimC · Posted: Mon Aug 11, 2003 9:20 am Post subject:

Ray I'll try this again. I posted an answer once but it didn't go through. The output trans on the speaker is a very old way of doing it. You can use a different speaker, but you still need that transformer. Find a place to mount it, then extend the wires to reach the new speaker. If the impedance isn't marked on the old speaker, measure through it with your multimeter set to ohms. The next higher common impedance (4,8,16) is what your new speaker needs to be. The schematic shows both the transformer and the speaker basket with a safety ground back to the amp chassis. It would be a good idea to keep this ground intact. Hope this helps, Tim

Guest · Posted: Mon Aug 11, 2003 11:36 am Post subject:

thanks Tim!

Ray

TimC · Posted: Mon Aug 11, 2003 5:33 pm Post subject:

Ray, I meant to warn you. The juice going through the primary side of that transformer is the B+ voltage. It's the highest in the amp, and can kill you even when the amps unplugged. The filter caps store this. You need to un-plug the amp, turn it on, and then let it sit a few minutes. Then short the primary side of the output transformer to the chassis to make sure it's safe. ( Wish he'd left an e-mail address. )

Guest · Posted: Tue Aug 12, 2003 7:13 am Post subject:

Thanks again Tim,
I want to mount the transformer somewhere inside the amp (and keep it well grounded)..this may require a new tranny since the current on is permanently mounted on the
speaker....Thanks for the headsup on the current..I knew it was on the high side (hence the step down transformer)...seems like a dangerous configuration to have that kind of flow in an open backed cabinet...any reason why they mounted the tranny right on the speaker?
Any thoughts on a new/old tranny? My schematic is intact but very old and yellow...

Ray

rsolinski@yahoo.com

TimC · Posted: Tue Aug 12, 2003 10:52 am Post subject:

Ray, you need a small, single ended output transformer for a Class A amplifier. About 5 to 8 watts. http://www.tubesandmore.com/images/AES2003p021.pdf Here is a link. Look at the P-TF 22905. 8 watt, 4 ohm and $27.95. There are several other sources for your trans. Antique Electronic Supply is another one.