Hi Madkeys,
There are 5 opamps, they are the little rectangular black chips. Pry between the black chip and the socket very gently, and then you should be able to just pull the chip straight up. Make sure you put the burr browns in with the same orientation as the original chips; the op amps have a little dimple or notch on one side, just be sure to put them in with the dimple on the same side. Easy does it, you may need to squeeze the pins on the new chips in just slightly, to get them in the sockets. Which chips did you get? Let us know what you think of the results Smile
I've modded the mod again, and now have BB 2134's in the 1st, 3rd, 4th and 5th sockets, and a LT1469 in the 2nd (compressor) socket. I think it improved the compressor a bit over the 2134 or 2604. The cool thing is that just by replacing the opamps, the unit can change it's sound character. The AD275 in the compressor has a totally different sound than any of the other chips I've tried. You can change the smoothness of the compressor by boosting or cutting the pre Gain knob. With the 2134's it is very clean, while the 2604's will have a small amount of noise.
mrc



But then...

Matt over at Black Lion Audio discovered this quick mod. Suddenly you have something that is noisy, but actually sounds pretty nice and thick and balanced.

The Bellari MP105 modification
http://www.blacklionaudio.com/roundsound.htm

The Bellari MP105 is the little blue and white single channel mic/line preamp that Bellari produced a few years ago. They might not even be available new anymore, but they are easily found used on Ebay for around $50 USD. The MP105 isn't a starved-plate design, so it's not as dull-sounding as other low-dollar hybrid preamps.

Black Lion Audio has designed a quick and simple modification to these that'll give you a really nice sounding preamp and DI. It's based on a more comprehensive mod that was done for a friend's MP105.

Here's what to do:

Replace U1 and U2 (BA4560 opamps) with a pair of Analog Devices AD826 dual opamps. They are socketed, so you don't even have to do any soldering.

Replace V1 with the 12AX7 of your choice. Black Lion Audio has long been a fan of the EI ECC83, which is an inexpensive reproduction of Telefunken.s long-plate 12AX7, and the Electro-Harmonix EH12AX7.

Now you're finished, simple as that! You'll enjoy it--it sounds wonderful on LD condensors, and it makes a great secret weapon on bass guitar!

Parts list:

(2) Analog Devices AD826AN, available from Analog Devices

(1) EI ECC83 tube or Electro-Harmonix EH12AX7, available from Triode Electronics