MC30 Type A-116-B Monoblock 30 watt pair. This is an excellent pair of MC 30 amps. My wife says i have to sell some of my toys... I plan on keeping last set (whichever ones are last to sell). About 12 years ago i started looking for the best examples of McIntosh tube amplifiers.
It took me years of searching to find best examples. The chrome on these units has almost no pitting, intact lettering, good paint, etc. The electronics have been blueprinted, all voltages are correct, the current balance is 1%, the electrolytic caps are new, the signal caps are matched to 1% or better, NOS tubes have balanced elements.
One early reversible upgrade i did was to change the P/S to the MC60 design. I replaced the 10 ohm /10 watt resister between the first and second B+ filter caps to a 2uH choke. This lowered the IMD dramatically. Back in 1948 when the MC30 was designed music had very little low freq (bass) energy.
On modern music (1960's to present) has much increased bass. In the stock MC30, bass cross-modulates into the mid and upper freq.
The ear is very sensitive to IMD (much more than Harmonic distortion). Compared to the MC40, MC60, MC75 the stock MC30 sounds like MUD. After studying the schematics of the MC30 & MC60's. And testing units on my Audio Precession, FFT Spectrum analyzer, and watching the B+ bounce on a Oscilloscope.I determined the issue was the poor B+ regulation. It is unbelievable how much clearer these MC30's sound. If you wish to have the stock B+, I will remove the filter choke and replace it with stock 10 watt resistor. The 12AX7, 12AU7 & 12BH7 tubes are NOS. Hand selected with balanced elements (very critical in a push pull amp).
They have SUPER RARE Mullard GZ34 / 5AR4 "4 notch" rectifier tubes. Due to lower IMD, the 5AR4 sounds much nicer than the old 5U4's. The reduced 5AU4 filament current is less stress on the power xformer (it runs much cooler). If you want the original 5U4 i will change out for you.Pictured is TAD 6L6 matched set. I may send a pair of Original, current matched, Sylvania 6L6's. Depends on sale of MC40 & MC30, which ever sells first will get their choice of tubes. The item "Mcintosh MC30 pair, excellent, near mint, Monoblock tube, 6L6, K66" is in sale since Thursday, December 12, 2019. This item is in the category "Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Amplifiers & Tube Amps". The seller is "65vettemap" and is located in Barrigada, Guam. This item can be shipped to United States.