mwl168

Cannot tell from the pic which terminal is for what, but maybe keep the tranny and PSU where they are and orient the amp boards and place the input XLRs so the signal wires are as far away from the tranny as possible.

Limited to 180 sets worldwide...

Ditto!

Maybe Tyll will come out of retirement and do a review and compare it with the Focal Utopia.

I have spare BH, GRHV and GRLV boards. PM me if you are interested.

Can KSA1156 be used in place of the 2SA1486 here?

Kevin has noted that KSC5026 is a substitute for KSC2752. Last I checked it was BO at Mouser but in stock at Digikey!

What's the amp on the left side of the Limited?

Or you can build the relay-based, full-balanced, true ladder attenuator that Kevin designed and there was a board-run for it a few months ago so there may still be PCBs available for it.

I compared the resistors to my board and, without seeing the trace, they look right. This amp runs much hotter than I expected so make sure you have ample heatsink. The 500K bias resistors set the output current.

@ vvega: check Craig Sawyer's Dec. 16, 2010 post on the KGSSHV thread. His rationale why a thin insulation pad, no matter the voltage rating, would result in arcing in high voltage application makes perfect sense to me.

My bad. I gave Jose bad information. The drop resistor is R19 which is marked 21K on the PCB. I got those two numbers mixed up...

Yes, and, as JimL stated, may also want to increase R12 to maintain (R11 + R12) close to 13.3K to maintain the gain and bandwidth as originally designed . EDIT: attached Megatron schema for reference. megatron.PDF

Jose's mod sets the CCS at 1mA instead of .85mA. This is likely the reason why the 12X7 plate voltage is quite a bit higher than the 245VDC I am seeing on my amp.

It may worth mentioning that, based on the plate characteristic chart of the 12AX7, this higher plate current also puts the tube in the more linear operation zone. Whether the effect is audible is debatable as always.