TUBE TIP: This amp really brings out the bad sound of old tubes. Keep your tubes fresh, and always remember to follow the power up/down rules for tube amplifiers. I recently switched to Groove Tube 12ax7 ECC83 pre-amp tubes and EL34L power tubes (RATING 6). So far these are the best tubes I've used with the amp.   CABLE TIP: Use a GOOD cable from your amp head to the speaker cabinet. It can improve the clarity of your clean channel while eliminating some of the muddiness of your distortion tone. Give it a try; you'll be surprised at the change in tone!   CONVERT TO 50 WATT HEAD: You can convert your M-1000 100 watt head to a 50 watt head by removing the two center power tubes. This will cut your impedance by half (example: 16 ohms will now equal 8 ohms, 8 ohms will equal 4 ohms) so be sure to adjust your speaker settings accordingly. DO NOT RUN THE AMP SET AT 4 OHMS WHILE IN THE 50 WATT MODE. THIS WILL CUT THE IMPEDANCE DOWN TO 2 OHMS, WHICH IS NOT SUGGESTED BY THE MANUFACTURER. Download the M-1000 manual for more information.   PERFECT CONNECTION GP-1000 PRE-AMP MODIFICATION: Change the cathode circuit on the first gain stage from 1.5k ohm/22uF to 825 ohm/.68uF. This mod gives a little extra gain and reduces the scratchy character of the distortion timbre.   NEW! PERFECT CONNECTION GP-1000 PRE-AMP MODIFICATION #2:Remove small 470 pF (mid-brown)caps from 1st and 3rd tube tubebase, or near the base at circuit board. These caps are between tube pins 1 to 3 and pins 6 to 9. This will increase high frequency overall and this way clean channel has a clarity of Fender twin.   Tube no 2 belongs to overdrive circuit and caps should be left original. Because GP-100 doesn´t have any high voltage bleed resistor, there might (should ;-) ) be a high voltage up to 300V at these tube pins, so be careful. It can be dischaged via 100 kohm resistor @ 3 minutes anyway.     This page features reader suggestions on how to modify your Lee Jackson/Metaltronix gear. The suggestions on this page are just that, SUGGESTIONS, and should be done only by those experienced with modifying electronic equipment. Metaltronix.net does not assume responsibility for damage to equipment or injury due to following the above suggestions. As with anything dangerous, if you don't understand it...don't do it!