kevin gilmore

try this, but the sizes are in the one extra file http://gilmore.chem.northwestern.edu/doug.zip

Newest version of the blackhole amp is 3.45 x 3.67 inches http://gilmore.chem....u/blackhole.zip not done in eagle however.

Very Nice

Fully loaded, on the 20v lines about 500ma On the 15v lines about 250 ma 12v line peaks of 30 ma 5v line I gotta look up

Have not even thought about the power supply yet. In the simplest version the smallest power one tripple works great. If you go with the outboard amplifier modules then you need something that does +/-20, then you can regulate that down to +/-15 with simple 3 terminal regulators, and +12 to drive the relays.

I modified the kgsshv power supply and batepower boards for the next board run. Bias is now a 3 pin connector, TST which is the 580v direct, 580V which is after the 5M resistor and the ADJ which is the center of a resistor divider for any other voltage. If you have a 10 meg input resistance dvm, then the correct voltage measured after the 5M resistor would be 386V.

Each balanced board should pull 600ma on each of the power supply lines.

courtesy the stax mafia http://gilmore.chem....sr1_sm_sony.pdf

This is what we do

can't seem to find the schematic for free, but a few places are selling it for $5 to $10. If you get desperate, buy it and post... If its actually a bad solder joint to the big black cap, pulling up on the relay end of it may temporarily cure the problem, in which case soldering just that pin should do it.

next time it cuts out, tap the relay first. If you can be certain that it is the relay and can't find a replacement, you can always short across the relay. On second thought it does look like a bad solder joint on C334. third thought bb204 is a grounding bar likely, so the relay may short the audio to ground, so shorting across the relay would actually make the sound disappear. They sure don't build them like this anymore. Going to try and find a schematic.

you are doing a single ended input right?? unbalanced to balanced is never absolutely perfect and the input tube matching side to side is the most important.

although i think that this is a bit expensive compared to everything else, it would be a complete plug and play stack. http://www.liquidware.com/shop/show/TSL/TouchShield+Slide plus and arduino uno and the ethernet board. as long as there are enough pins left over to drive the i2s bus and a rotary encoder with buttons, should be ok.

Anything is ok by me. Just has to write to the pcf8574 chips and write to a color display. We already have some of the code for arudino for this,it's minimal. I don't know if the linux for the raspberry pi does real time or not, an interrupt in the middle of programming the volume control could lead to interesting noises. The video output or the hdmi is probably not suitable for our uses unless someone knows of a really small display that takes composite or hdmi. Touch screen also a real sweet idea for local control.

disconnect all wires to the transformer and measure the transformer for shorts between the windings.

They should be 4700uf/25v caps, and the unregulated voltage should be 21 volts.

It should be clear by now that all of us are nuts. Some of us are VERY nuts. At least a couple of the members of the stax mafia are criminally insane. My dream is to make the all dht direct coupled triode thing in a machined non magnetic damascus steel chassis. I'm trying to find a suitable piece of lapis now.

I certainly have not built one yet. Don't have enough time.

I'm almost done. Going to order different opamps for the servo's today. And i've redone the output using the audio quality opamp for that purpose and now a different opamp for the servo. Currently the input stage dc offset is 200 microvolts which is perfectly fine, but i'll get it down more. Without the servo its actually 4mv which is known to most people that use ths part, but evidently not others. The output stage with the audio opamp as the servo comes in at about 5mv, and while fine for headphones, driving monster power amps is not a great idea. I got to listen to it over the weekend, and compared it to a number of the most expensive preamps out there, and it holds its own just fine. Kerry is testing the multiamp outboard amplifier. Sure seems that for control the way to go is an arduino with the ethernet board, a ethernet to wireless converter, and then your favorite ipad like device talking to the preamp via a webpage. And then an oled display on the preamp to show levels. The biggest mess up with this was the fact that the discontinued omron relays had a different pinout than the panasonic relays i'm now using.

You want +/-500 volt power supplys, you have to give a little. Both the 10m90s and the 2sa1968 are much more thermally stable with respect to current, but are only 900 volt parts. The 10m90s is designed to be a sharp cutoff device and 50ppm. The ixtp01n100d is not designed this way. Stacked current sources don't perform as well in a standard configuration and have to be bootstrapped to perform at low Thd levels.

I just for fun finished testing the new balanced dynahi into 8 ohms, and it actually works and works well. Unfortunately the power supply limits to about 1.5 amps, which ends up about 18 watts into the load, of which about 3 watts is pure class A. Everything gets very hot doing this. So if you put monster heatsinks on everything and beef up the power supply you can probably get more. The other thing is going to also run at +/-30 volts, but will put out 20 watts pure class A into 8 ohms. The power supply for this is going to be substantial.

sigma22's will work fine. Probably you want one power supply per channel. I never tried to drive speakers with the balanced board, that would be the equivalent of a 4 ohm load per side. Should work, might get very hot. Probably something like 18 watts. Birgir and I are working on a pure class A speaker amp (or lcd2/3,hf6) thing that is 20 watts into 8 ohms. Its a krell ksa50 clone down graded a bit but way more bias. All the new modern onsemi transistors.

1) i can do a board for 7189a's. But its going to be bigger because its now 8 tubes instead of 6. Also don't know what a 7189 is going to do at 800 volts. And its not a triode. 3) The bias pots take care of any differences. Self bias for these tubes rarely work, same as 6ca7 which mikhail tried to use with self bias. 4) bias pots are between -430 and -400 volts.

And you have the nice benefit that the supply won't blow up if one of the amp boards goes south. (or north if you live on the other side of the world) And its also current limited, so if one of the amp boards decides to short, no flying parts. I might be able to squeeze another .25 inch on the width if its that close.

AH yes, the age old question. About 12 volts. So an unreg of 412 volts. So if you pick the transformer correctly you want about 440 volts with the load. The 450v caps are rated 450v, 500v surge. If your AC line is 10% high, then you are pushing it. and if your AC line is 10% low, then you drop out of regulation. Better is to go with the 500 volt caps which are 550 volt surge. For a while the 500 volt caps were not available, but it seems people are making them again. Otherwise you have to go with the kgsshv supply which puts 2 x 450v caps in series, for lots of headroom. This also increases the physical size a fair amount. For the exstata you really want +/-300, so you set the zener strings for 300v and then you have plenty of headroom with the 450v caps.