New MKIIa.....couple ?'s

[6br]

I recently picked up a nice IIa to run as a clean amp with my 2204 Marshall. Pretty much no frills....60w, reverb, fan and modded for an fx loop and MV. After replaceing the broken reverb with a MOD tank and cleaning all the pots, jacks, sockets, I have to say this is a thumping little amp. Cleans sound pretty close to my old Twin....a bit tighter but has the same punch, clarity, depth ect.

I have heard that IIA's and some B's have a trim pot to set the bias. There is a blue trim pot next to the large filter caps. Is this for adjusting the bias? I have it circled in the pic.

http://imageshack.us/photo/my-images/802/0381.jpg/

EDIT-----> FWIW The IIA's blue trim pot is for adjusting the bias. Nice feature to have if you want to use something other than Mesa tubes.

 

[lerxst88]

I would guess thats a bias pot. Also the Celestion speaker makes me think that mark was modded along the way.

Super cool amp though!

 

[6br]

Thanks......its no beauty queen but the price was right. :wink: I'll have to keep a eye out for a matching 1x12 cab.(JBL / EV)

 

[igfraso]

I would guess thats a bias pot. Also the Celestion speaker makes me think that mark was modded along the way.

Super cool amp though!

Being the Mark II-A a dark amplifier, I understand the original speaker was the Eminence MS-12 (150 Watt) and the optional (upgrades) speakers were the Altec 417-8H Series II, the JBL K-120 and the Electro-Voice EVM 12L.