kevin gilmore

No reason for an extra buffer

I am sure that the design is a version of his current source feeding a buffer output stage. Possibly ac coupled. With a fair bit of feedback.

it may have been cute when schiit came out with its original batch of cheap shit. all sorts of compromises necessary to produce something for $149 But now we have schiit competing with massdrop competing with monoprice, producing seriously compromised product for prices approaching $700. All sorts of issues including virtually no class A output power, split rail power supplies, low component life due to some really high chassis temperatures, noisy external switching power supplies and flyback switchers internally. Throw away product for sure. When you can buy real products from real companies for $500 or less.

the cfa input is a diamond buffer and is biased thru the base currents of the input pair.

I think it may screw up the first stage bias currents, but you can certainly try it.

It's the complex impedance of the cables that can cause oscillations if driven from a zero impedance output. input impedance of the amp does not matter. this is why a buf634 can oscillate and it always has a gain less than 1

you can always add the protection circuit board.

If you are driving 20ft or more cables, 50 ohms is a good match for the cables. For headphones no resistance necessary

there is a difference in voltage gain. 6db.

8M$ total sales based on serial numbers.

Even with the grossly inflated prices cavalli eventually went under due to too many hands in the cookie jar and shit quality requiring a lot of repairs, especially the liquid carbon. when there was only one standard for measuring distortion it was easy. Now that there are a number of adc based distortion devices each with different firmware and software, and digital filters you can generate impossibly low distortion numbers that are meaningless. jude might want to look at how measurements were done many moons ago and emulate that. Far more useful information. i think a reasonable number on sales exceed 8M$ over the 8 year life of cavalli. Lots of people are going to take a bath, just like singlepower

the thd+N is .0075%, and although it does not specify, its likely at 1khz. look at the schematic posted above. about 15db of feedback around the grid of the tube. Lowering the input impedance to bipolar levels or lower and kind of negating any possible use of an input tube. Also the plate current source. spice indicates a second harmonic distortion of -74db at 1khz (.02%) and a 3rd harmonic distortion of -109db (.0003%) at 1khz however at 10khz the second harmonic is -60db (.1%) and the third harmonic is -96db (.002%) you can work out the summation on your own. plus of course the messed up soundstage due to the inverse phase. Something the plankton experts seem to ignore. In reality, with an old school analog thd meter, the numbers are going to be much much higher. and of course this is all measured with a 300 ohm resistor. Use a real load especially low impedance, and the numbers go way up.

2nd harmonic and 3rd harmonic vs frequency is what influences sound signature the most. bipolar vs mosfet outputs makes the most difference. there is no cavalli house sound. This amp is bipolar outputs, the LCX is mosfet.

because i'm lazy, taobao links for liquid gold clone and LL please. approximate schematic here. too lazy to finish the plate servo. some resistor values obviously wrong, probing from here with voltmeter to Iceland seems unreliable. (and kinda slow) .1% thd at 10khz 2nd harmonic. which is not that horrible cth2.PDF

Going thru the schematic its kind of obvious that for the 1/4 jack, this amplifier inverts phase. Not sure about whether the wiring on the 4 pin is flipped to fix this problem. people sensitive to phase, or at least notice the difference, and this amp is going to sound different.

8significant areas on both units have circuit board heatsink area. Still you could easily attach real heatsinks to those areas and put more holes in the case to let the heat out. And then bias up the output a bit more. This one uses a 28V power supply. So output rails are +/-14v, pretty low voltage swing. Outputs are MJD243/MJD253 and are bipolar. tube is current source plate load, capacitor coupled to a virtually identical copy of the liquid carbon output stage (current feedback/bipolar) with a different servo.

If the new LCX sounds worse than the original, its probably because of the rail splitter, otherwise the circuitry and parts are identical. I have never seen a rail splitter test well. The original squarewaves all burned up due to heat and other stupidity, but otherwise sounded really nice, still the only headphone amp I know of that is both current feedback and all of the voltage gain in the output stage. The re-done version is still a sweet but low powered amp. dynalo and supersymmetry dynalo still out perform everything else in their power class and as far as I know, no one has ever been able to burn one up.

massdrop and schiit seem to be trying to out cheap each other. clearly this thing is much better built than the original for less than half the price. whether the protection circuit will prevent it from blowing up if you insert unbalanced and balanced headphones is currently unknown. but cost cutting is evident everywhere. external switcher removes the need for line power inside the chassis (joutenheim) and the AC rated power switch. But rail splitter causes all sorts of issues. Virtually no heatsinking so the amp runs pretty much class B. etc the CTH is the same thing. More rail splitter because its single ended.

I wonder if amb knows that alex is using his protection circuit?

well at least it has a dc protection circuit which the original did not have, and its sure going to need it, absolutely no heatsinking of any kind. OH look, a rail splitter that's necessary because of the ultra cheap single output switching brick. At least its actually built better than the original at less than half the cost. i'll bet that plugging in both unbalanced and balanced headphones is going to cause it to blow up. just like the original

it is one board per channel for the tube. your choice of tube front or tube back (different layouts)

don't build the DHT one unless you plan on spending piles of cash on tubes

I really like that knob

845 in a megatron configuration is what you want

so the options for the new woo amp 1) plate resistors, they already said its not this 2) inductors, they already said its not this 3) center tapped inductor, you get about 6db of gain with this. 3a) push pull output transformer. all sorts of issues with gain and power with this 4) solid state current source maximum voltage gain of 6sn7 is about 20, maximum voltage gain of 300b is less than 4 somewhere there are likely to be input/interstage transformers and then you are still going to have trouble getting to a voltage gain of 500 or more if you want some feedback to reduce the distortion. the viva evidently is also low on gain, and uses and output transformer. why people produce shit like this I do not know