Rare pair Quad Macmod 405 (Steve McCormack/ Mod Squad) Monoblocks – rebuilt and updated
This is a rare pair of Macmod Quad 405 monoblocks – the product that made Steve McCormack famous and let to the creation of the Mod Squad.
Steve McCormack took a pair of Quad 405 stereo amps, and made the ultimate version of these current dumping amps – 2 monoblocks – by removing a lot of the protection and limiting circuitry and upgrading the components.
Quoting from quad405 (dot) com:
“MAC MOD 405
The respected audio designer Steve McCormack (USA) soon realized that the basic concept of the Quad 405 ("Current-Dumping") was great, but the idea was destroyed by crummy parts and a drastic protection circuitry. In consequence he offered a modification kit for the 405. The ultimate Mac Mod were mono amps. The modification contained the following changes :
•Current Limiting removed
•Improved IC fitted (LM 318)
•Faster Drivers ( Motorola MJE 15031 )
•Faster Output Devices ( Motorola 2N3773 )
•Improved Resistors (metal-film 1% by Resista Mk3 or Corning RN-60 )
•Improved Capacitors (Wonder Caps, Wima, dipped mica)
•Improved Wiring (Audioquest) and Plugs (Tiffany)
The Mac Mod 405 surpasses the original 405 in every respect : It was a great sounding amp which could compete with the most advanced high end amps in these days. Harry Pearson of the "Absolute Sound" magazine wrote an enthusiastic review about it. I still regard it a pity that Quad-UK did not overtake the Mac Mod as standard, because the improved 405 is an exceptional amplifier. The only caveat about the complete Mac Mod is, that the ultimate version (= mono amps) has too much power for the delicate ESL-57 (protection circuitry mandatory !), though power output is quite right for the ESL-63.”
A few years ago, I opened up my Macmods to inspect them, and discovered that the power supply caps were leaking. As a result, I rebuilt them, and they should now be ready for a few more decades of service.
There are a few more details that are not mentioned in the list above. McCormack had installed a + and - voltage regulator on the board, quite a few bypass caps, ferrite beads. IEC plugs, and probably other mods as well.
None of changes I made are drastic: I replaced the power supply caps with 40,000uf (4x10k uf) Nichicon caps, the LM318 was replaced with a chip holder (so you can roll opamps) and OPA604APs, the diodes were replaced by ultrafast soft recovery diodes, and the caps were replaced by Panasonic FM low ESR caps. I did not change any of the cap values from what Steve McCormack had used.
This amp has never sounded better!
I have the original Macmod "manual".
Due to age, physical condition is 5/10.
PLEASE DO NOT BUY THIS IF YOU CANNOT PAY IMMEDIATELY WITH PAYPAL. I WILL NOT ACCEPT ANY OTHER FORM OF PAYMENT. PLEASE DON'T BOTHER OFFERING TO WIRE ME THE MONEY, ETC.
THEY ARE HEAVY. SHIPPING WILL BE VIA INSURED FEDEX GROUND. PLEASE ADD ANOTHER 3% FOR PAYPAL.