GrindingThud

^^ like he said.... I use these: http://www.mouser.com/ProductDetail/ON-Semiconductor/MPSA56RLRMG/?qs=sGAEpiMZZMshyDBzk1%2fWi%2fPUgtclNldl2ZkToUCMhk0%3d

Mmmm, bacon Oreo:

Like this: http://gilmore.chem.northwestern.edu/kgdynalobalssproduction.pdf

Chambord oxidizes pretty quickly after being open and will eventually turn a nasty brown. Cognac will oxidize also. Scotch is somewhere around 6 months or so after opening. Unopened they last indefinitely.

Its running happily in my SuSy Dynalo with no issues that I've noticed. Provides a nice little startup delay and cuts out if I induce DC on the output.

Doh...I Must have been dazed by staring at purple on purple for too long.

Better batteries than lipstick, Chapstick, or that God forsaken silly putty. Nothing effing worse than silly putty in the dryer! The batteries won't hurt anything, even if they leaked all over, just throw them away even if they work. The could leak later on. If it makes you feel better, wash them again (the sheets not the batteries).

Hand traced and it looks ok to me. Subtle differences in the schematic vs the board: C2 is 100uf in schematic vs 47uf on board. C1 is 4uf in schematic vs 4.7uf on board. The top two tiers of the triple darlington emitter resistors float in the schematic and are output referenced on the board. Also noticed the ground in and out connections, the 100uf and .1uf cap grounds don't have thermals...not sure if you typically use them there or not. What's the gain set to on this one? I having trouble figuring that out. I plan to get a proto board spun when I have time...much more compact than the KSA5.

I have those for my pinball machine boards. I might try those on my next build.

Have the files been posted for this one yet?

Foo! Mistakenly swapped +/- on one of my boards... Fortunately I caught it quick and only the opamp and 7915 smoked. Was a slow day so I decided to do some chassis work and biasing.

Still have not finished installing the balanced input jacks, but the protector circuit fits nicely in there.

Ready for test. 1st install will be in my SuSy Dynalo.

Bummed I missed it live...thanks for the link. Would not want to miss a really good one.

As a kid in New England, once a year everyone would put "large stuff" at the edge of the road by their driveway for the town to pick up and bring to the dump. We'd run around before the town would do pickup and rummage through everything and grab what we thought was the good stuff. Tubes, speakers, and tube amps were my favorites. I'd pull every tube out of everything I could find. What makes me sad now is how many desireable tubes we popped with BB guns. For a long time as a kid I had the coolest Leslie 251 organ amplifiers and cabinet speaker.....they had the schematic on the side and I learned how to solder while fixing them up. Why my parents put up with it, I'll never know.

Aphex Twin posted a bunch of previously unreleased and demo material....been listening to this all day: http://104.236.16.63 https://soundcloud.com/user48736353001

Did more testing today and built up the second board, but used MPSA and the THAT on perfboard instead of the Chinese fooo I have in the other. Board came up ok and tweaked easily to a couple mV all around prior to installing the servo. This was a little easier to troubleshoot on the big heatsinks. Seems the balanced output is dead quiet with low gain (20K feedback) and either SE or balanced input, but SE output hisses loudly between either side and ground regardless of input. I think I'm missing something obvious.....where's captain obvious when you need him. Anyone have any ideas or experience using the amp with single ended output?

No, but now I plan to!

Get a cheap one from Amazon with a USB port: http://www.amazon.com/Sony-PS-LX300USB-Stereo-Turntable-Black/dp/B0015HOFZI/ref=sr_1_1?s=electronics&ie=UTF8&qid=1422485763&sr=1-1&keywords=usb+turntable http://www.amazon.com/PLTTB3U-Turntable-Recording-Digital-Software/dp/B002PF4YKU/ref=sr_1_7?s=electronics&ie=UTF8&qid=1422485906&sr=1-7&keywords=usb+turntable

Kewl

I'll need to double check gain values and position and try again. I tried dropping the 200K to 20K to get I think 3:1 (kept the original cap) and it did not seem to change the noise any....so I assumed I dorked something up along the way or have a noisy part somewhere in the front end. I'm assuming weird symmetric noise because it's much much quieter on the balanced output than from either leg to ground. I may try singles for the 2sa1349/2sc3381 before I tear it down too far. What is the recommended singles for those and are they unobtanium too? I'm liking the THAT340 more and more but come this far on this boad and determined to figure it out. I appreciate your help on all these amps and for making them available, I'm having a blast building them up.

As I wait for the enclosure, I tried hooking headphones up and running some sound through it. Seems I may have a problem with noise (hiss)...huge hiss. The hiss is much quieter listening across the balanced output than a single side to ground, but still hissy. When listening to a side, the noise is less if I short the same side input to ground directly. Input grounded through the pot makes no change in noise. Thoughts? One thought I had was that my input sand is crap. I may try to spin a small mezzanine board to drop that340 in place of the jfets and use mpsa in the associated input leg like in the new board.

Ok, I've got power (one board assembled). The smoke did get out the 1st time though. Q22 (BC556B) died on power up and the Negative rail sat at ~-5V. Powerup was in the dual track config. I swapped to the untracked config and changed the transistor and it came up with some mystery smoke but otherwise ok. Then swapped back to tracking config and it still works. I looked all over the board and can't figure out where the mystery smoke came from.....but it did smell transistory. The 1K resistors are not on this board either...should those be spliced in? or only necessary if the current limit transistors are in (not installed now and no plans to put them in). Nice strong +/- 30.0. ---- Edit: had the time and went and did a quick amp board checkout. I don't have full sized heatsinks yet, so these were short tests. I was able to tweak the offset across positive and ground and negative and ground to be symmetric and about 12mV. After I put the servo in it brought it to around 1mV balanced and each side to ground. Very nice. When I went and measured the bias current (voltage across the 10R output resistors) I was getting a pretty consistent match for all N and P devices in the same channel (6mA device to device), but across channels overall (O+ to O-) there is about 150ma difference. Right now one side is 550mA and the other is 400mA. Is there a way (or is it even necessary if output DC is nil) to get the sides the same?

This one? http://gilmore.chem.northwestern.edu/boards/dynahibal9.zip

JB is 300V/mil