kevin gilmore

been working on this one a while, with all the popular transistors disappearing, I hope that this one won't go obsolete before the boards are out. I don't think so because Fairchild has said that the bc parts should be available for at least 5 years but onsemi said the same thing. This one is a diamond transistor input set, used as a voltage to current converter. A pair of Wilson current mirrors with input and output cascade as the VAS and a triple darlington output stage. http://gilmore.chem.northwestern.edu/cfa2.pdf if someone knows of better surface mount parts to replace the bc series, I might as well do that from the start. ft >150mhz, hfe >100 Vceo >50 etc

how do you drive bipolar single coil relay with single switch to ground?

Birgir will be building the T2's. I am just going to watch. smaller version of my attenuator board, definitely want to see this. if you make it surface mount only, then you can shrink it a fair amount. The one knob control is definitely one of the better ideas.

new board uses 1 x 2n7000 http://gilmore.chem.northwestern.edu/protector3.pdf

no bjt's on that circuit board anywhere

servo has a limited range and is slow

high powered DC amplifier. More than capable of frying headphones if you put dc in the input. Protection circuits always a good idea

not sure where the schematic is, will look later 1n914 or similar 47uf non-polarized ceramic

sure, but that costs almost as much as the rest of the amp especially if you go for the 47 position model

input pot? dual alps 10k (mouser does not sell this) or anything else you can get that is 10k.

those can be replaced with a couple of different parts all of which are fully isolated

definitely like how the diy stuff seems to be outpacing a lot of the commercial stuff.

6db unbalanced 12db balanced

looking very good

not sure those are real, the price is way to cheap. I paid about $1 each for the real ones from mouser.

yes the 4686A parts would be in place of the 3675. And since they are isolated, they are easier to mount. The only parts that would not be isolated are the j29 and k216. In a couple of places the 1486 can be replaced with the ksa1156 because they are used at only 250v. And those are fully isolated too.

microsoft iis i don't think so and i'm way to lazy to do a web page if someone knows a way, i can certainly can do it what i can do is sort the directory by date and put it into info.txt file which i will do later

actually 400V - (-110V) == 510v of bias (which is close) but the negative voltage swing is -110v to -400v (less the voltage of the tube) which means real nasty and early clipping

kgdynalobal7 is the all surface mount transistor version of the ss dynalo balanced. yep, lots more surface mount in the future

you do know that the wood is conductive... you need a ground wire for the wood. (no kidding, granite audio puts a ground wire on their faux granite case)

switcher is completely open loop. double the input voltage, and it will try and make +/-500 or so. And parts will start flying.

never had a schematic of the power supply in that unit but i'm pretty sure its the filter resistor and should be the same as r41 i think the srm212 is very similar, will look later trace out the power suppy from the transformer, should be a couple of diodes directly to a pair of caps, then resistors from those caps to the second set of caps

6V filaments are AC the 300V comes from the 450V thru a resistor. no need for extra power supply

plate voltage with respect to the cathode is about 340 volts

no current source in the input stage of the exstata just resistors