Mark IIA?

mkVplayer · Aug 28, 2015

I just got an amp dated 5/19/80 on the underside of the chassis, not sure if it's a IIA or IIB. 100/60, reverb and EQ. S/N 5206

The underside of the chassis has a metal plug where the FET switch by V1 is that I saw in a thread here about an amp from january of 1980 (http://forum.grailtone.com/viewtopic.php?f=3&t=70285#p478176). Mine also has two jacks one marked Send the other SW, on either side of the 2 reverb jacks. Not sure if the labels were added later or not but they are in red and everything else is in black marker.

In addition to wondering the model I'm wondering how to use the loop (if it has one) and how I connect the volume pedal to the back panel pre out/pwr in jack that they mention in the IIB manual, if it is a IIB that is.

I assume SW is a TRS footswitch jack for Reverb and Graphic? Since the other one says Send I assume it's not a stereo plug so should that go to effects and then the effects out goes to the jack on the back panel that says Pre amp out/Power amp In? If not, how is it done?

Thanks in advance!

lovetoboogie · Aug 29, 2015

Hi...

It is squarely a IIA...

The send jack under the chassis is a dedicated post-master "preamp out" that breaks contact with the power section. You can use it as an effects "send". The effects "return" is the pre/power jack on the back...

Depending on if you have reverb and/or eq, then the "switch" jack will either function to turn the eq, reverb and/or both on and off using either a 1/4" mono or 1/4" stereo run out to a 1 or 2 button footswitch depending on if you have one or both add-ons...(most early IIA's only have an EQ on/off wired to that switch jack)

That dummy plug in place of the fetron switch is not something i have seen. it was either modded or dressed out like that from Boogie per customer request...

mkVplayer · Aug 29, 2015

Thanks!
Is there any difference between the back panel send and the one under the chassis?

Also is the "last" master before the power amp the "lead master" or "master 1"?

I guess putting a vol pedal or any pot between the underside send and back panel return would be a true amp-wide MV? Or is one of the front panel MVs post power amp?