This is a mod that David Allen of www.allenamps.com offers on his website. I got in touch with him to see if he still does these mods and he's backed up through the summer with orders for his own Allen amps, so he's suspended any mods or repairs on Fender amps until further notice. Does anyone else besides Allen do a similar Bassman mod such as this? ______________________________________________________________ Here's the info from the Allen website: "Bassman® Head conversion - there are lots of 65-70 Bassman® heads with the odd AB165 circuit which was quite a departure from traditional Fender circuits. The BASS channel is not really voiced well for guitar and is often not used. This conversion rebuilds the entire circuit board so the NORMAL channel is the more desirable AA864 circuit (about like the NORMAL channel of a Super Reverb) and the BASS channel becomes a really cool lead channel with a tweed/Plexi flavor to it. The DEEP switch goes between the huge cathode bypass capacitor associated with the 5F6A Bassman to the much smaller capacitor used with the Marshalls. This channel has an extra gain stage, is more aggressive and has more harmonics for a great lead channel. You can use an A-B switch to switch between the two channels with each having its own volume and tone controls. It makes a much more usable amp for guitar. Many end up preferring the BASS channel to the classic tone of the NORMAL channel. The conversion is $199 plus anything else that might be needed as part of normal service such as new filter capacitors, tubes, grounded power cord etc. I have done several of these and they are very popular. The modifications are reversible and there are no holes drilled or controls not properly labeled."