this was supposed to be kept quiet. i should have said that in the pm. ah well. need a working filament to test new filament circuit. don't care if the grid is shorted or the plate has holes in it. and i will neither confirm nor deny the existence of the megatron2.

so short answer is no. the apex opamps already have enough gain and don't need any tubes in front of them. using the right apex opamps will result in a fairly decent amp, but it will not be portable. it will need heatsinks. minimum would be 5 watts per chip, 20 watts total. 4 times that of a...

the felista had a much heavier chassis. and a tube rectifier power supply. and the extra power transformers to go with all of that. And a tube regulated 300v supply and the transformers that go with that. so its has to be heavier. 30 lbs does seem reasonable.

some people are using the cfa3 to drive raal headphones, so i would expect it to drive the lcd-r just fine. but i have not tested this.

25 lbs with the transformer box? not sure how that is possible. the felista megatron was 70+ lbs. the problem with kgsshv and some of the other designs is that the parts are obsolete. So you need to find someone that has real parts in stock. or you need to find someone that upgraded and has an...

more output transistors. transistors are higher power dual chip. more voltage. lots more current. otherwise identical. wonderful for high efficiency horns.

no difference in the circuit. thru-hole transistors replaced with surface mount versions because the thru-hole are discontinued. split into 2 pieces to reduce cubic inches. the high voltage version requires a 3U chassis.

with 30v rails that would be 8 watts balanced into 200 ohms. with the 97db efficiency, that should blow your brains out. and probably set the headphones on fire. if not you can always build the newest version with 45v rails.

closeup of carbon cc with some expensive resistors https://drive.google.com/file/d/1fZLzzK3y1fsEMtAuo4Vni479GFOPETOt/view?usp=share_link felista audio megatron before https://drive.google.com/file/d/1w0toxF82xzemQt5dvpHiTADJYn1F4Tb9/view?usp=share_link...

some people may recognize this guy https://drive.google.com/file/d/1qbNrQ3eFbPUBZpZgnlN2AMELV9ZKXJuN/view?usp=share_link

I finally got my C8 convertible, $99k (plus 7k for winter wheels and tires). The matching porsche was $230k. I have driven both extensively. The C8 is an infinitely better car with mag ride and eLSD differential. No comparison. porsche has a slightly nicer interior and better leather. There is...

there is an error in the linked post. power supply is +/-400v definitely NOT +/-1400v

the manley is not balanced, but otherwise exactly correct. and the d10 has less voltage swing than the 3es. can save a bunch of money and build it yourself. https://www.transcendentsound.com/masterpiece.html $699 plus tubes + chinese d10 clone evidently a 6sn7 driving a 300b as a cathode...

definitely a piece of mica some of which got getter on it when the getter was flashed. its possible to shake the other piece down to the other mica where it won't be able to short out anything. so the tube might still be usable. but i would never use that tube again. as it is looks like the...

that is way to thick to be getter material. also looks to be the wrong color. likely a piece of mica insulator.

SRPP is not constant current. For SRPP the output is taken off the cathode of the top tube. For constant current the output is taken from the plate of the bottom tube. big difference in performance. Especially true because the electrostatic load is not a constant impedance.

that particular design is a dual opamp, so you have to make an adapter for that, otherwise correct.

a fully balanced version of this is easy to do. also no feedback. IF you can get the parts. The +/-15 supplies can be eliminated if you use high voltage servo opamps. One of a number of projects i am working on, waiting for the parts situation to at least stabilize. a much higher power CFA3...

1/((r15+tvr1)*2)

the jfet input stage is not pulling enough current to turn on the second stage.

no idea. change q1 first.

i would probably swap the fets first since you can't test them with a voltmeter. yes they run at 200 microamps each. part numbers are BL grade on most amps i have seen. measure to ground the connection between r5 and r6. check value of r26

real 2sj74 replacements available here https://diyaudiostore.com/collections/frontpage/products/matched-jfets?variant=39335246954569

if d4 on my schematic is not lit, then q1,q9,q10 are a problem. 2sa1413 are easy to get (to252 version required) OR... input fet is toast. i apologize for the misunderstanding on which led is out. very different problems. you should probably do a schematic that matches your board. the blown...

flip the leads and try again. open output transistors will influence the feedback to the jfet source. otherwise pull the resistor and measure out of circuit. if its really open, you are going to want to replace that first. if the resistor is open likely the jfet is toast.