Recent content by timv

my coliseum 2B has the same logo in the same place so I'm pretty sure that is stock.

I just got a 3 channel triple rec serial number is 27xxx, just looked at pics I took and it is a rev c+ and the board doesn't have a spot for that cap anymore. I'll update with full serial number when I can.

The way I've always seen bias adjustments setup would have been adding a pot to that empty resistor spot labeled R311. The resistor you replaced is the front end of the voltage divider and usually the adjusted value is the one that goes to ground. I suppose how you did it does work but if the...

If you've worked on Mesa amps before it is very easy to follow the layout and figure out which resistors need to be replaced. It will be two of them. The power transformer is shared but each side has its own complete circuit after the main voltage. Look for the pairs of 47uF 100 volt...

Without power to the relay it will latch to its normally off state whatever way that is. When the relay receives power, when you turn on the preamp, the relay clicks to whatever state it needs to be in for what channel and mode is chosen. Relays do not stay in whatever state they were in when...

Relays make audible noise when they switch. There are parts moving inside to open and close the connections. Makes sense that in different modes when turned on/off that different relays click.

That would be nice but no. Two completely different styles of circuit boards. I am probably going to copy the reversed schematics posted on here for a 2b with fx loop mod and make it like that. My studio preamps distortion sounds great but the 2b stock is lacking a bit.

R117 is the spot for another bias resistor if needed. That is where a tech would install a resistor or potentiometer to adjust the bias for another set of power tubes. Do a search for R117 on this site and you can find plenty of reading on it.

Hello, I just received my new to me Coliseum 2B. EQ, Reverb. Bought off ebay. Made the seller a low but decent offer and he accepted. It is serial # K110 dated 9-14-81 and several things about it seem like it may be a very early one to me. The back panel doesn't have the 3A marking blacked...

Hey, I know the extremely informative site known as the boogie files has been gone for a while now. I was curious if anyone had all the info off of it saved and wouldn't mind sharing it? I'm starting a blog documenting the amps I work on, owned, etc and want to share any information I can on it...

i believe that is a mitchell amp... I had a pro 100 that looked just like that. i believe they were sued for them.......

This whole package was sold. Thanks dominick9998.

I'm guessing shipping to california should only be 20 maybe 30..... $25 would be fine....

Not taken yet.... I believe you can get new knobs from mesa. The ones for the pots are the same as newer mark series amps and those can still be bought, and the eq sliders knobs are available. I was going to send it to mesa and have the footswitch mod done and have them put the knobs etc...

This was sold. Thanks dominick9998 for the quick local deal. This is an older Mesa Boogie Quad preamp with some cosmetic issues(missing knobs, power light) but functions 100%. This preamp sounds great the only real issue is no footswitch. I bought a fu2-a off ebay but it doesn't work...