kevin gilmore

i've been saying that the switches in a r2r dac were a real problem for many years now. especially the ttl versions. the teac ud-701n is the cheapest ($4k) of the esoteric dacs that use custom and hand matched switches. I expect that better switches will be the new big deal in the next couple of years.

amir using his AP measured the koss amp directly which promptly went into power supply overload at about 100 volts into the 100k input impedance of the AP. then he measured one of the stax tube amps and came up with equally useless graphs. refusing to build an input attenuator he continues to believe in his measurements. if he had tried to measure a kgsshv-carbon without an input attenuator he would have blown the AP to crap, as the kgsshv-carbon is more than happy to put 900 volts peak to peak stator to ground into a 100k load. amir is as i have said before is just another idiot with an AP. and continues to find a way to represent an amplifier as 1 single number. which purrin has correctly labeled as amirNAD. simmconn on the other hand did correctly build a 10x attenuator and has been measuring and posting graphs. and knows what he is doing.

the original larger boards were compatible with amb's lcduino with no software changes. the smaller board i did with the color touch screen programming thing from australia.

probably not. glich is too fast. try it and let us know.

you get a dc glitch in the output. not enough to cause damage to the headphones.

i have bigtime problems with their cables. for cables with a cable shield the shield has to be at ground potential, not 580vdc. with 2 wires on each stator, the cable is double the capacitance that it needs to be. really messes with the frequency response and high frequency load presented to the amplifier. 6aq5 output tubes paralleled, so maybe 5 watts into 8 ohm speaker tap. e180cc as input tube. medium gain. circuit highly similar to early dynaco, pentodes driven as tetrodes with ultra linear transformer taps. unregulated power supply is a bad joke.

that person is a moron. the orpheus has 3 capacitor coupled stages. the BH is completely dc coupled.

surface mount version of the 47uf cap

opa551 is a cheaper opamp that is good to 60 volts opa445 is good to 90v. at least that is what the pricing used to be

As many of you know i have been searching high and low for the world's best headphones. I have finally found them.

well it was designed for 450v power. but really we are talking about only a couple db of difference. a minimum of -100db thd+noise. if you swap the transformer then you have to go with higher voltage rated power caps.

ttc004 might now be a better replacement, different package.

simmcon, first graph not shown. are you measuring balanced? and what additional attenuator are you using?

those resistors are output stage bias set.

no idea, have to look where those resistors go. if those are the input resistors, anything over 50 ohms is fine.

there are gerbers for the k489/j689 and the 2sc3381/2sa1349 pretty sure the 2sj109/2sk389 is compatable with the 2sc3381/2sa1349 board you are looking for that340.zip

the inductance is going to be really low in any case.

your first link definitely works. But i have an extremely old version of this Precise Universal Hand Tapper, Assures Straight Perpendicular Tapped Holes - 265-110 - Penn Tool Co., Inc and this is definitely works, hard to use in volume applications Precise Mini E-Z Hand Tapper, Assures Straight Perpendicular Tapped Holes - 390-252 - Penn Tool Co., Inc

thats a great way to break a tap and ruin the heatsink. get a tapping jig.

that is one of the ways of building it.

if you can't copy it now...

well there are 2 ways to do this. instrumentation amp and inverting/non inverting. pick one, they are roughly equivalent.

posted for the owner who will comment much further. (for some reason he cannot publish high res pictures)

there is no way this is going to be a diy product.

lazy huh? ubaltobaltubeschem2 - cadcam.zip ubaltobaltubeschem2flip - cadcam.zip