1985 Marshall JCM 800 2210

This is the Switch-Channel 100 watt Reverb version of the famous JCM 800. It has the ability to switch between a piggy-backed boost circuit or the cleaner and more straight forward “clean” circuit. The clean channel is differentiated with the more concise Treble/Bass tone stack. The reverb is definitely a different vibe than the Fender style circuit being darker with a shorter decay and far more subtle. As this customer already owned another JCM 800 (the original 2203 version) we decided to go with a different tube lineup consisting of EHX and TAD preamp tubes and JJ KT77’s in the power section - this was also done to reduce noise in what can be considered a noisy amp. KT77’s are a drop in replacement for EL34’s, but they have higher headroom and a gutsier sound in the low to low-mid’s. A lot of people into hard rock love the sound of the KT77 and don’t look back after hearing them. This amp came in just needing a full workup, having had some not so stellar but minor work done in the past - along with a few choice mistakes made by a previous tech resulting the the phase inverter having resistors of wrong and interchanged values.

The amp was given a full restoration. All the axial lead electrolytic capacitors were replaced with upgraded temperature rated Vishay/MOD/CE brand electrolytic’s. The multi-section cap can’s were replaced with new German made F&T 50/50uf 500v type units. The power dropping resistors were upgraded to 3 watt Metal Film type. This was done for better noise floor and reliability. A new Cliff 1/4" Jack was installed to replace the incorrect replacement that was present.

The amp was completely re-tubed with the following compliment. V1 = EHX 12AX7 GOLD, V2/V3/V4 = TAD ECC83-cz, V5 = EHX 12AX7, V6-V9 = JJ KT77 Matched Quad. I picked out this lineup specifically for this amp to give the best balance of tone, reliability, and low noise. The adjustable Fixed Bias was set to %58 Class AB Plate Dissipation with a B+ of 442 VDC. All pots were cleaned and hardware tightened.