kevin gilmore

If you ever have to remove a smt device for repairs you risk damaging The board. On the preamp board I have turned the opa1632 into a dip On a smt adapter because some of the chips don't meet dc specs. Nothing wrong with smt to to220 adapters these are the future for stuff like this An all smt stax amp will never happen because the resistors can't handle the voltages.

surface mount. But sooner or later we are going to have to make adapter boards to use these parts.

BD139

this is the mouser part number 532-CLP212G

Buy the ohmite clip that is designed for the heatsink You also need a thermal insulator because the tab is Electrically hot. Will post the part number later.

it should come as no surprise that only the 2sa1968 actually performs perfectly at 450 microamps. http://gilmore.chem.northwestern.edu/megatron.jpg place for the 330k resistors also left there.

Inu must be playing with spice yes it would have to be a 2sa1968, because nothing else is stable at 500 microamps. or a 2sa1486. The 10m90s won't work. Actually the real number is 450 microamps. Neither of these are in current production. Could probably get away with ksa1156. dn2540 also won't work because leakage at likely temperatures is more than 500 microamps. and with the 12ax7 in the first stage, the gain is a bit high at 65db. so i'm playing with a 12au7 at the moment. brings the gain down to 52db. removing the pot probably does not help with the space needed for the current sources. We will see...

not unless people let me make the board bigger.

Biirgir is going to do the prototype run very soon

27 ma per tube is exactly correct. The teflon octal sockets on ebay are about $10 each the teflon 9 pin sockets seem to be about $12 each likely way cheaper overseas. Not sure how much the capacitors are. maybe about $600 in parts total including the power supply, not including the transformer or the tubes.

Does more than 1 count? 3 of the 4 units that were built by the one guy (i forgot already) work, i'm not sure who owns them. The 4th unit is erico, and his should be fixed soon. I know there are a few units overseas already, don't know those people either. i get a bunch of thankyou's in emails, but usually can't put the avatars and names together.

Moved the 7912 a bit. All of the heatsinks are grounded. It may not show up well. I made the thermal's thicker so that they can be seen now. I've never had any trouble with a regular soldering iron soldering solid ground pads. It makes a significant difference in the performance of the amplifier, those little crosses add a fair amount of resistance and increase noise. So i like to keep everything in the signal path with the lowest resistance to ground.

updated files http://gilmore.chem....du/megatron.jpg http://gilmore.chem....versalpower.jpg someone please check that i did not flip the feedback, or other stupids

Yep, i was planning on that.

The pattern for the bridge rectifier, i'm aware of, but since the printing never shows up... but i will fix it anyway. How i missed the diode on the tl783 i'm not sure, i know where it cut and pasted it from, and the original has the diode ?? Thanks Inu.

universal power supply with option for C- supply and time delay for tube high voltage http://gilmore.chem....versalpower.jpg updated amplifier board http://gilmore.chem.northwestern.edu/megatron.jpg

all of these, roll forever shortest distance socket to socket is 2.3 inches i can make the board bigger if it needs to. 6L6G (and A,B,C versions) 5881 5932 7027 EL34 6CA7 KT77 WE350B Compatible with an adapter 6550 KT88 KT90 Compatible with stupid adapter EL360,3D21 and every other thing mikhail made for the esx

i like this idea.

There must be 20+ original designs. I'm going to give away all the board files, and nothing prevents people from building whatever they want. But a compact monster amp can't be a bad thing. The thing with the 5687's is that they behave very badly if you push them over +/-300. And given the Rp of the tube, the most you can get is 1150 vppss. Since there are no 1kv triodes unless you use really expensive dht's you have to use el34's strapped as triodes.

Perfect. Sometimes the web is not cooperative. Will check the fit later.

actually someone suggested a name over there for another product. But i like that name for this one. http://gilmore.chem....du/megatron.jpg Only the RK27 will fit, both the RK50 and the dact are both much bigger. i'm having trouble finding the datasheet for the quad, so if someone can find it. otherwise the board has to get longer. The pot is at the back near the inputs, and a shaft goes to the front. Same as the T2.

The Quality goes in before the Name Goes On. (i've been waiting 35 years to use that one now that it is no longer trademarked) And you really only have to match pairs.

.15% for a tube amp? Pretty low... (notice the . ) what i may do later is flip around the input stage and put a pot in the middle. Rk50/dact is easy. Board is going to get bigger.

This is absolutely at the T2/BHSE level. Remember that 50% of the output tube heat is filament heat, only 10 watts per tube goes actually goes to make audio. (ONLY) Because of the feedback, the prototype actually does .15% thd, and slew rates of over 100 volts per microsecond. The power supply is the kgsshv power supply at +/-450 volts. Or the simpler one. The auto dc balance requires very stable power supplies, so if you build the simpler one, the output dc will drift over temperature. A triple kgsshv power supply, +300, +/-500 would give this thing even more output swing. I can do that later. I suppose that you can go completely unregulated if you want to do really simple.

board size with the attenuators on board would be 11.5 x 10.4 rotated input section, board is 9 x 9 inches http://gilmore.chem..../beacssmall.jpg total tube power with filaments 180 watts. going to be perfect for winter.