kevin gilmore

Not exactly. In fact mikhails amplifier was a fully dc coupled amplifer with a HUGE amount of dc drift over time and temperature. And the drift was not necessarily positive or negative, and it was well over 1 volt or more. So mikhail had to put in an output cap, and since he did not know the direction of the drift, he had to put in 2 caps back to back in series. But then because of the caps he picked, and the time it took them to actually charge up, he biased up the center pin, so that it did not suck so bad (meaning no bass for the first hour or so) and then told people to keep it turned on all the time. Serious clusterfuck, every part of the amp. http://gilmore.chem.northwestern.edu/dinglepower2.jpg

well i have some of the connex teflon ones, but those are very hole size specific and don't match any standard pattern. Also have a couple of the old ceramic ones for the original kgbh, similar to the ones used in your amp...

a stax of staxjacks http://gilmore.chem.northwestern.edu/staxjacks.jpg i wanted to make 40, but friday got in the way... this is enough for a while, the 4 people getting chassis this month, let me know whether you want low bias or high bias jacks. If the material comes in today, i will start on more angle pieces. All of the parts for the 4 are done, so they will ship as soon as the stuff gets back from anodizing.

mikhail used this technique in the squarewave... all poly/teflon caps exhibit some piezo electric effect. and electrolytics just don't belong in the audio chain.

2 inch long #4-40 nylon screw and a few nylon nuts. holds the diodes in place, no chance of a short.

somebody please find me something with heatsinks for the sides. 13 x 13 inch inside dimensions.

Mine already gets 29 mpg on the highway, and 21 in the city. No joke. Beats the crap out of the jaguar which could only do 14 in the city. The C7 with the 440hp direct injection engine should do 35 on the highway. (being 150 lbs lighter, and the efficiencies of direct inject) Maybe even better depending on the aero-dynamics. When i was growing up in high school, one of the people on the block had a very rare XKE with a V12 engine, and 4 x 2 barrel carbs. he was adjusting it weekly. Maybe even more often. Had floating things with ping pong balls in it to do the adjustments. I'm likely to cut up the wood with a diamond saw.

trying to decide which direction to cut the knobs from. paging Dr. Wood... http://gilmore.chem.northwestern.edu/lv1.jpg http://gilmore.chem.northwestern.edu/lv2.jpg http://gilmore.chem.northwestern.edu/lv3.jpg http://gilmore.chem.northwestern.edu/lv4.jpg

I got the michelins at discount tire. I needed to deal with the problem immediately. tire rack is useless. the tires won't fit in the trunk (what trunk) and they won't deliver to anywhere convenient. I'm now good for another 40k miles. By then i will have a C7. (or else) Jaguars are beautiful cars. I owned one. I will never EVER own another one. At least it never left me stranded. But the every single month service repairs were really abnoxious. Got to love the impossible to adjust dual throttle linkage on the V12.

2007 corvette. My daily driver. Including the winter. Which is why i need all season run flats.

Inu has a listenable unit. YEAH. I'll let him describe the sound. In less than 2 weeks he will have the knob and custom piece... Then he will be the first with a finished FINISHED T2 Better than my version of "i've died and gone to heaven" Birgir, stop being a slaggard and get yours done... Just got a raw piece of OUTSTANDING wood from craig in GB... Lets see what kind of knob(s) i can turn this into...

yep, that is what i'm looking for. the other ones make noises as they turn.

So the transformer is going to be 4 inches in diameter. Which means that the inside of the box is going to have to be 13 x 13 inches for a single chassis thing. Heatsinks both sides.

here are some pictures, don't read too much into them. high impedance is 300 ohms, low impedance is 32 ohms, you can figure out which is which. This is before changing the CCS currents http://gilmore.chem.northwestern.edu/dsav1.jpg http://gilmore.chem.northwestern.edu/dsav2.jpg http://gilmore.chem.northwestern.edu/dsav3.jpg http://gilmore.chem.northwestern.edu/dsav4.jpg http://gilmore.chem.northwestern.edu/dsav5.jpg http://gilmore.chem.northwestern.edu/dsav6.jpg http://gilmore.chem.northwestern.edu/dsav7.jpg http://gilmore.chem.northwestern.edu/dsav8.jpg http://gilmore.chem.northwestern.edu/dsav9.jpg http://gilmore.chem.northwestern.edu/dsav10.jpg http://gilmore.chem.northwestern.edu/dsav11.jpg http://gilmore.chem.northwestern.edu/dsav12.jpg more pictures friday or saturday after i change the ccs resistors. thd measurements from above, well over 1%, IM approaching 2%

I think you actually need to measure that resistor. I know what it looks like, but i've been told that it supposed to be brown black violet which would be 100 meg, resulting in a lowering of the bias by about 9%. There is no way you can safely do 300 volt bias when you have the amplifier doing +/- 600 volts. That or someone did the modification wrong. With koss, you can never be sure. Clearly koss has some manufacturing issues.

OK, absolutely positively i should never rely on anyone who thinks they know what they are talking about. The bias on the koss headphones is absolutely close to 600 volts. Here is the proof http://gilmore.chem.northwestern.edu/kesp1.jpg So the tan resistor has absolutely no markings. The 10 meg resistor is in series with the +630 volt power supply (plus or minus a bit, on batteries, about +600) The unknown resistor is to ground in parallel with the cap. You just can't measure that resistor with it in circuit, which is the failings of everyone else. http://gilmore.chem.northwestern.edu/kesp2.jpg and this meter measures to 200 meg. http://gilmore.chem.northwestern.edu/kesp3.jpg Now usually when i see resistors like this, they are 1 gigohm. But even if that resistor is as little as 250 meg ohms, the bias is still (referenced to 600v) a minimum of 575 volts. I could bring the thing to work where i have meters that measure into the gigohms, but there is no reason. THE KOSS ESP950's ARE HIGH BIAS HEADPHONES!

Do not assume that i paid anything even close to retail for the stack of test equipment i personally own. I've been collecting stuff for 35 years. 4 oscilliscopes at home, all solid state, one portable and one transportable. signal generators, tdr's, spectrum analyzers,... The pile is probably worth more than the house that contains the stuff. 4 years at zenith during the beginning of the solidstate tv days gave me a lot of knowledge in messing with high voltage stuff without killing myself. An art that is clearly long gone.

my bad... 75 mhz these are the new ones with silicone inside them instead. TEKTRONIX|P6015A|1000X High-Voltage Passive Test | Newark.com Tektronix P6015A/2R 25 MHz High Voltage Probe - eBay (item 320511121758 end time Jul-30-10 16:09:08 PDT) eventually you will probably find it on ebay for about $500

Insulating version of 8n80c definitely a good idea. I did not even know it was available. Someone needs to verify that it can dissipate enough heat though... Definitely do not hook up both the 100 volt and 120 volt windings on the filament transformer at the same time, pick one or the other. You can hook up all the wires on the high voltage transformers if you wish. This error has been corrected on the layout so that if there is another board run, this won't happen again. Doh.

Lots of problem with the capacitive dividers too... matching over frequency very miserable. What you want is the old tektronix 1000x probe thats filled with freon. Good for 30kv. And a frequency response up to about 10mhz. Its about 1.5 inches in diameter, and two different colors of blue. I have one, i keep it locked away so that no one drops it which would trash it. The 100x scope probe should do it if you are careful. Here is what absolutely everyone including me does...when they don't want to blow up something expensive. Little pomona box with a male bnc on one end, and a female on the other. Add two series back to back zeners from center to ground. 100 volts. Insert in the line between the scope probe and the scope. Ignore the readout pin if you have a scope that uses that. I'll verify the koss bias voltage tomorrow, but mine certainly does and has worked at 600 volts... For a very long time. Need to put the L'espresso on the bench and test for distortion and rise times...

Oops, thats definitely a bug... Will figure out how i messed that one up... My transformers don't have 100 volt taps. I hate messing up the simple stuff. DEFINITELY DO NOT HOOK UP THE 100V transformer windings if your transformers have these windings!!! Thats what happens when i try to make it goof proof

Morphsci is today's winner... That went fast.

Actually you have it backwards. Because of the circuit lands on both sides of the board, chassis ground is pretty much connected to circuit ground anyway. Using a cheater cord (same as cutting the earth ground to circuit ground) is definitely not a good idea.

One person has just canceled, so there is one more set of boards/chassis available. First person to PM me gets it. But it still will be a few months and it will ship as a complete set. (figure about $1500 plus shipping)