kevin gilmore

very nice

yep 10:1 or 100:1 with an impedance of R1 = 500K or more

second row, second and 4th are pictures of the real item if it does not have the slits in the plastic by the pins it is not real

you need a 120pf dummy load, and a minimum of a 10x high impedance attenuator otherwise one accident and you blow the crap out of the AP

so remember ZENITH... The quality goes in before the name goes on. (ok you have to be at least my age to remember this) (and between 1965 and about 1980 compared to everything else it was actually true) well cavalli is the reverse of that The quality never goes in, but sure is a pretty box It would have been so much easier to add terminal blocks on one end of each board

that looks good to me, but I would never attempt to build something that small

so alex released his latest $4700 piece of crud http://cavalliaudio.com/index.php?p=morestuff&stuffId=13 notice the LDR volume attenuator. notice the distortion of the LDR http://www.diyaudio.com/forums/analog-line-level/80194-lightspeed-attenuator-new-passive-preamp-134.html#post1520243 notice the pile of soldered in jumpers tying the 3 boards together making it absolutely impossible to ever fix the thing. at least the load for the tubes/mosfet is now more rational on a single heatsink kind of feel sorry for all those llmk1 and llmk2 owners whose amps are now worth nothing...

its been posted already. since rkv is not a sponsor there, they probably don't give a shit. clone board now available, usual place. if you read the French forum, the manufacturer has already decided that 1:5 transformers cause all sorts of grief, and now they are making 1:14 and 1:20 transformers. Between a rock and a hard place they are. The amp may be just ok, and only for high impedance dynamic headphones. The transformer box is a clusterfuck for electrostatics.

because if you clip the output like you would do with testing with scope and signal generator, the top fets blow due to reverse bias on the gate. mosfets on the output are a bad idea, but some people want them.

2sa1831 is only an 800V part. So you would have to cut the power supply voltages down to +/-400

very nice job. you are ready to do the T2.

so I did some playing around with a lundahl ll9202 transformer. setup to drive electrostatics. Using all the lundahl specifications, and what I get on the scope looks almost identical to this simulation. top graph is frequency and phase 20hz to 20khz, the bottom graph is 1khz square wave. Using a full synthesis of the rkv amplifer. synthesis by the way of the rkv indicates a real impedance of about 800 ohms. http://gilmore.chem.northwestern.edu/rkv.jpg while not exactly the same transformers that are in the verto, my guess is that the verto looks like this or worse. this is not a minor aberration to the frequency response. This is a complete fucking of everything. The graphs on the rkv website as well as everything out of eric65's mouth seem to be a complete fabrication.

half of the differential gain comes at the output stage. there is a offset and balance control. This takes care of everything. Really!

won't matter as long as you use all the same of each part in an amp

no, absolutely not. Output stage is a differential amplifier.

when using the rca inputs you have to have a switch that shorts xlr input minus to ground.

So any otl tube amp with a capacitor coupled output is going to have one very large turn on thump. except for Mikhail's disasters that left the output cap charged forever (black gates stay charged for months) That turn on thump can be 50 volts or more. Not a good idea. And the original cap coupled square wave probably had a 10 volt or more turn on thump to charge the 2 x blackgates on the output.

servo is taken from the output. can't possibly stabilize when the output is shorted to ground. in fact, probably makes it much worse.

1) of course not. and it is usually a bad idea to short out any amp to ground 2) idss 3) both of those should work.

charge them up for a week discharge them discharge them again measure

whether it has a loop output makes no difference unless you have installed extra switching relays etc. So if the pot is 50K and turned to zero, then the impedance is 50k from the headphone amp. If the speaker amp and sub amp are also 50k then the dac see's about 16.6k. But some amps may short the input, or open the input when not powered. build a set of loop thru cables.

http://www.jogis-roehrenbude.de/Verstaerker/PCL805-KH-Amp/Schaltung.jpg by the way there is a cap in series with the grid that is missing on the bottom output tube its a futterman design with a lf351 solid state front end. would be much better if you build it with 6as7

so take a look at the 2 scope graphs here http://www.head-fi.org/t/439657/headamp-blue-hawaii-special-edition/5685#post_10741753 First one has no vertical scale. My guess is that it is no more than 20 volts peak to peak. And look at the very rounded edges of the triangle wave. If you did the first one at 100vpp it would look absolutely grim with lots of ringing. And really horrible slew rates. I pulled some lundhall transformers, and a few other things this morning, drove them with a krell ksa50 and got nothing even close to acceptable. Same with a srd7 and srd5. Serious amounts of deliberate fudging of the specs here. But the worst one is the Ri of .01 ohm. Not even the biggest of the atmaspheres can come close to this number. Off by at least a factor of 20. Adding transformers just fucks things up. Same with the electra. Now if you were gaku-on and were able to wind the transformers correctly (like quad does for its esl63) then things would be different. And the price would be more than building a solid state amp. No free lunch.

5pf is 3db down at 278Khz 3pf is 3db down at 500khz

10k input resistor, 55k feedback resistor should work fine. 4 volt peak to peak balanced input results in 22 volts peak to peak balanced output. 110k feedback resistor results in 44 volts peak to peak balanced output