OK this info comes from the ampgarage.com forum -

   Quick user's Guide to the Overdrive Special.

***********Front Panel:****************
FET: This input is for an acoustic guitar pickup.
NOR: This input is for an electric guitar

Volume: Sets the amount of gain for the preamp section. Use the "Master" to set overall amp volume. Higher levels of the Volume will distort the 'Overdrive' channel more.

Bright Switch: Adds a treble boost to both channels Mid Boost: (similar to the bright switch) Functions in both channels; adds some extra kick, especially in the overdrive channel.

Jazz/Rock: The Jazz setting is a quieter, lower gain setting.

Treble/Mid/Bass: These self-explanitory controls function in both channels. They are bypassed with the "PAB" (preamp-boost)

Drive/Ratio: These function only in the "overdrive" channel. The Drive, works in conjuction wth the "Volume" to control the overall gain or distortion. The Ratio is a seperate master volume. To set the Ratio control, go to the clean channel and set the overal clean loudness of the amp with the Master control. Then engage the "overdrive" channel and adjust the Ratio control to get an appropriate loudness of the overdrive channel.

Master: sets the overall loudness of the amp. Raises and lowers the loudness of both channels together.

Presence: Controls the amount of negative feedback. Higher settings reduce negative feedback and give more distortion. Lower settings increase the negative feedback on the power supply and reduce distortion.

********Back Panel ************

Ground Switch: Places a capacitor between one of leads from the mains to the ground. May eliminate hum in certain situations.

ON/OFF; Controls power to the amplifier. Make sure the standby is "off" before switching on. If the tubes get fed full plate voltage (about 450v) without being warmed up first, there can be damage to the cathode of the tubes.

Standby: controls the high voltage power to the tubes. Has the effect of silencing the amp. Let the tubes heat up a few moments before disengaging the standby when first powering up.

Fuse: Should be a slow blow 3A. Used to protect the circuitry from shorts.

Effects sent and return: This is a passive effects loop, There may be gain mismatch between the input of this jack and that of an effects pedal. Try it and see how it works. If you are serious about having an active loop, you can buy or build a Dumbelator which will plug in here and will have its own input/output into which the effects will plug.

There is a filter incorporated into the send/return jacks that is activated when a cord is plugged in. One can produce an overdrive smoothing effect by placing a patch cord in the send/return jacks.

PAB and OVERDRIVE switches on back panel: With the foot pedal unplugged, these switches control the preamp boost (which disengages the tone controls for some extra gain) and the Overdrive channel (which adds gain and distortion to the clean channel). So, they would be "ON" when set to "Manual". When the foot pedal switch is plugged in, keep these switches on "Pedal" for correct function with the foot pedal.

**********Inner Potentiometers (trimmers)***************

FET INPUT TRIMMER: located on the board near the FET input. Adjust this to change the gain of your acoustic guitar plugged into the FET input.

OD TRimmer: Located closest to the guitar inputs on the rectangular board. Adjust for the lowest setting that will produce a good overdrive tone.

Phase input trimmer. Located closest to the power tubes. Used to balance the two sides of the phase inverter tube.


It is a lot to take in, but I hope that it works.

Best Regards

Well Here's Mine!
I ordered the cab from Gabkits.com. Had minor fit problems, but made sure that they knew about them, otherwise a nice cab.

I had the faceplate made by Amplates.com (great place to work with)

The Speaker cab is a Lopoline.com closed back 2 x 12 loaded with Eminence Governors.

The Amp.... For tubes I am using the Groove tubes Marshal High Gain kit, which consists of hand picked V1 and V2 Preamp tubes and a matched/ Balanced Phase Inverter. For Power Tubes I am using the Groove Tubes E34LS.

I have Modified the amp with London powers Power Scaling Kit - http://www.londonpower.com/catalog/product_info.php?cPath=7&products_id=27 (warning: install this kit only if you know what you are doing, if you do not and you want the kit, then order and find a good amp tech to install it for you.)

It works amazing!!! I get full cranked tone at bedroom levels, it operates buy interrupting and adjusting 3 power supplies and can turn your beast into a 2 watt amp with all the tone!!

I have also recently added a Mercury Magnetics Choke and Output Transformer. The addition of the OT has really brought this amp to life. There is so much more clarity in the individual notes and the amp is so much more responsive to picking dynamics. I am waiting for my new Mercury Magnetics Power Transformer expecting it in about a week!! That will be the end of the mods to the amp. Well here are a couple pictures.