Different EH-150 Schematic?

[mumford]

Does anyone have a schematic for the version of the EH-150 that had 3 6c5 tubes?

I love my buddy's and was thinking about trying to clone it. I had a different model that didn't sound anywhere near as good, so I'm going to go for the model he has.

[Phil_S]

Does this help? It's EH-160.
http://www.harpamps.com/gibson/pg_0026.jpg

[David Root]

If you do that one DON"T use that power supply, it's obsolete and dangerous. That is the AC/DC version. This one is the one to use.

[mumford]

Thanks, fellas!

[Structo]

Those old amps used a field coil speaker.
The speaker doesn't have a permanent magnet so they use an electromagnet.

The strange thing about that amp is that it also uses a choke.
The old Hammond organ amps used field coil speakers and they used the coil as a choke in the PS.

So on this amp they are relying a lot on the inductance to smooth the DC ripple current.
Since it only uses four 10uF caps.

In the specs for a 5U4 rectifier I believe that the first cap should not be over 32uF.
And I believe a 10H choke is max as well.

I have an amp with a 5U4GB which has a little higher specs such as you can use a 40uF first cap.

Figuring out the power transformer for that amp will dictate how you build the power supply.

If at all possible, crack your friends amp open and measure all the pertinent voltages to get the specs.

Remember also that that amp was built when the wall voltage was 110v.
Although on the schematic it shows 110-125v.

I would measure the secondary taps of the PT and remember that a 5U4 rectifier drops around 40-50v from the secondary voltage.

Also notice that it uses a transformer for part of the phase inverter.
But on the schematic I show below, it doesn't.

[Structo]

Here is another EH-150 schem

http://www.schematicheaven.com/gibsonamps/eh150.pdf

This guy goes through one of these and gets it going.

Wow, 1936.
Check out the components in this antique.

http://www.timeelect.com/eh-150.htm

[Structo]

Check out this clean example.

[img:570:855]http://www.gryphonstrings.com/instpix/29600/296004.jpg[/img]
[img:855:570]http://www.gryphonstrings.com/instpix/29600/2960010.jpg[/img]
[img:855:570]http://www.gryphonstrings.com/instpix/29600/2960022.jpg[/img]
http://www.gryphonstrings.com/instpix/29600/29600.html

[Andy Le Blanc]

I like how the interstage is used to also provide feedback to the cathode of the 6c5.

[M Fowler]

Here is a version I am building right now PTP.