View Full Version : Altec 1566A Preamp

08-27-2006, 08:03 AM
How can I wire this up as a guitar preamp. It came with a 4722 Microphone Transformer and a 15095 Line Transformer.

08-27-2006, 12:28 PM
Connect it just like you would a hi-z mic, tip (hot) to input barrier terminal 2, and sleeve (ground) to #4. Remove any transformer modules from the octal socket immediately to the left of the barrier strip, and insert a jumper (bend a short piece of 12guage solid copper to make a jumper) from pin 5 to pin 7 of the socket. For safety sake, double check the 1566 grounding, including making sure that input term #4 is actually earth grounded. If you need help with the 1566 output connection, I'll need to know exactly what you're connecting it to, including impedance and sensitivity.

08-27-2006, 03:26 PM
I'm doing to install it on a Peavey Supreme Solid State Guitar Amplifier Exfects loop for boost during solos.

08-27-2006, 03:54 PM
Whoa! Big difference!

Ignore the last info then, which was for a direct connection from the guitar, to actually function as a preamp.

Not sure how well the 1566 will interface in an fx loop, as I expect the fx out will already be way hotter than anything the 1566 wants to see as input. If I can find an online manual with your PV model's specs, I'll get back to you, but I have a feeling it won't be with good news.

08-27-2006, 06:07 PM
OK thanks. How about to input straight into the amplifier?

Thanks Again.

08-27-2006, 09:10 PM
Didn't find a manual, but assume the PV fx loop is ~line-level, lo-z.

To run the 1566 into the PV guitar input's not likely a good idea either, just the thought of highly-overdriven SS sets my teeth on edge. However.....

If you used the 1566 to effectively replace the SS pre section of the PV, you'd have a tube pre with a SS main, which will likely sound much better than what you're used to, with a little tube growl and still not blowing anything up.

To do this, connect your guitar to the 1566 input as I first suggested, then go from the 1566 out (try the 600 ohm connection shown below first) to the fx loop input. This should work without risking damage to anything, but you might lose the use of some of the PV controls (just not sure without a schematic).

As with any tube gear, make sure the 1566 output is connected to a load before power up.

08-28-2006, 12:28 PM
Thanks so much for the help. I'll let you know how it works.

08-30-2006, 06:21 AM
Hooked it up as directed. Even changed the 12AX7's. Tried it with the guitar into the input of the PV and also in the effects loop. Removed and jumped the pins on the transformer base. and tried both output configurations with the line transformer in the circuit. Do you or anyone have any literature (operators and or service) on this device?

08-30-2006, 06:30 AM

There's an online manual at;


click on manuals, then sound equipment.

08-31-2006, 06:44 AM
Thanks for all the help. It works great. I'm using the input just like you told me to do and using the direct output. Sounds great considering he's (my son) going through a 100 watt and a Carvin 4 X 12 bottom. I removed the junk Celestion speakers and installed 4 Altec 417-8C 12" guitar speakers. Crunch and punch to the Max. Thanks again.

08-31-2006, 07:46 AM
Duuhh...my fault for choosing the balanced out setup, just what I'm used to on boards with balanced fx loops. Should have known direct for a guitar amp. Glad you figured it out! Having a 4x12 full of 417s can make any amp sound better. Keep that kid makin' music! When he gets really good, help him find a good old Fender or Marshall all-tube amp to replace the SS PV (but keep the 417s!), you won't regret it.