kevin gilmore

for the 100mm heatsinks whats the real maximum distance between the bottom of the board and the top of the sicfet package

if that is what people want. what clearance do you want? I would think 30th minimum any ground plane on the top of the amp board is going to be problematic due to all the surface mount

the fat power supply boards do say "up to 680uf /550v" i'm going to update the power supply boards today so that the power caps exactly line up when done mirror image. currently there is 30th of difference which might be noticeable if you punch holes in the top of the case

I would mount the caps on the board, and punch holes in the top panel.

those tubes are really designed for lower voltages and much higher currents. So for a push pull speaker amp, great for lots of power, a single pair is probably good for almost 200 watts with the right transformer. But for a BH, where you really need 800 volts or more (can actually go to 900 these days) not a great idea

kt120 and kt150 would work great in the megatron circuit, possibly at higher currents. a kgst would need an additional buffer to drive the grid correctly, and a much bigger current source.

the price for those 2 boards is not really out of line.

increasing the current resistors on the 900V supplies only.

those are the right thing. and the ebay clones, all did circuit modifications, some have half the output transistors, some messed with the bias etc. None are exactly the right thing

those are designed for cs3310 and not for anything else that i'm aware of

washers near the tubes are too close, use smaller washers

tree in the forest behind me cracked and totaled 1 section of fence. can't even get back there to take a picture

i have built a prototype from cfa2 boards and the ubaltobal board, so i know the design works. it sure is a lot of parts, all attempts to shrink the parts count usually ends up with something with very poor performance

nope and definitely nope one of them has one of the two words (well sorta)

version 6 of the lv boards posted, same as previous version except added the optional pot and resistors version 7 of the boards posted, 4.1 inches long, because one person wanted bigger power supply caps dual version 6 as previous version with the optional pots and resistors version 6 singles are 3.725 x 2.4 version 7 singles are 4.1 x 2.4 dual version is 3.67 x 4.32 with respect to the 2 singles in series, you really need 1 of each of the 2 boards, not 2 of 1 of them for lowest noise. (not that its really measurable on any dvm < about $5k)

Nope, not even close

actually a while ago, and I have not found it yet, I did a hybrid, because the cavalli supply blew up with no load. so what it actually did was lower the current under no load conditions so that the shunt transistors did not overheat. But in the end the performance was no better than the power supply at the time. And the golden reference HV versions are substantially less noise than any of the previous supplies. And probably not any more complicated.

the suspense is killing me

the polarization of the diaphram is something that changes on the order of minutes or longer, no way are they changing that. What they probably did is something similar to shure, shrink the distance beteen the diaphram and the stators and then run a lower voltage amplifier. There are p-channel fets that would allow a push pull amp with a very small class A bias that would run on +/-300v

you can be sure that the amp inside the headphones is a version of the hev70. that is, mosfet current source, mosfet driver. likely gain of 5 to 10. gain will have to be fixed because no feedback on the cable. and no room for output capacitors so the power supply is likely +/-300v or so because anything more would be very unsafe. (like +600 and 0) could i drive this headphone with a better front end, you bet. 8 tubes, how can you possibly use 8 tubes unless 4 of them are for the dac.

amazing, what kind of wood?

what you should do is schiit style. mount the things on the bottom panel.

one other thing, i went to bigger heatsinks since that picture when i'm driving both boards. the heatsinks are the ones from the blackhole amp driver

i had a variac on the power transformer and lowered the voltage to about 3 volts above the regulation minimum.So it really depends on how much voltage is on those transistors. With a total of about .5 amp, they can get warm.

At +/-200V power supplies and 200V bias, its super easy to do a real push pull electrostatic amplifier. All surface mount. You can be sure that there will be more iem electrostatics.