FrankCooter Posted March 16, 2012 Report Posted March 16, 2012 So what do people think of this http://gilmore.chem....rn.edu/bate.pdf Looks interesting. Why not substitute dirt cheap Russian 6N1P-EV for the 12AX7 in the first two stages? More linear, and if you used CCS plate loads probably wouldn't loose that much gain. Probably require less feedback as well. Any reason for not connecting the "tail" of the LTP to the neg. HV rail? Use Russian k40 PIO coupling caps, and if you used 6P14P output tubes you'd have an amp built mostly of Soviet era military surplus. Ton of this stuff around. You could call it the T-34 (a cheap, simple, but very effective WW2 tank).
Pars Posted March 16, 2012 Report Posted March 16, 2012 You could call it the T-34 (a cheap, simple, but very effective WW2 tank). Hehe... like!
kevin gilmore Posted March 16, 2012 Report Posted March 16, 2012 (edited) layout updated to support 12ax7,6dj8,6n1p ... http://gilmore.chem....rn.edu/bate.jpg yeah i know working on a low-res screen is a bitch. will update with higher resolution later. Could add current sources everywhere. Including the output tubes. That is going to increase the size and require heatsinks. As far as the resistor to the negative rail, Lots of people do that, but i see no reason to, and besides unless you are going to use a delay relay to turn on the high voltage, you would end up with 800 volts across a cold 12ax7. Which can't be a good thing. This is great sounding, about as simple as possible, and something anyone could build and get to work. Birgir can voice the thing by picking the capacitors, or anyone else can add comments. The only ones that need to be >800v are the ones between the 2nd and 3rd stages. Picture will be updated soon. Edited March 16, 2012 by kevin gilmore
spritzer Posted March 16, 2012 Author Report Posted March 16, 2012 800V across a cold ECC83 would certainly not be a good idea. I for one see no reason not to use ECC83's in this amp and please stick with the new JJ's as they are simply better than anything else out there, new or nos. For caps the layout will fit Wima MKP10's but given their rather large size, most other standard polyprop caps should fit. The double wound Mundorfs will probably not but most other boutique caps should also fit. We could go with a full CCS madness for this but the whole point of this amp is something simple that truly anybody can build.
Beefy Posted March 16, 2012 Report Posted March 16, 2012 We could go with a full CCS madness for this but the whole point of this amp is something simple that truly anybody can build. Would a CCS on just the first and second stages be possible? I can't imagine that they are running a lot of current, so shouldn't need huge heatsinks or board space......
spritzer Posted March 16, 2012 Author Report Posted March 16, 2012 Possible, yes, but I just don't see the point of doing it.
kevin gilmore Posted March 16, 2012 Report Posted March 16, 2012 Another electrostatic release by the stax mafia 2 just this week http://gilmore.chem.northwestern.edu/bate.zip this needs checking, for errors, but all the sizes of the components have been checked with mouser.
FrankCooter Posted March 16, 2012 Report Posted March 16, 2012 I like it a lot. If you built it pt/pt , it's a weekend "junk-box" project within easy reach of a 2nd semester electronics student. Looks like you're going to have about 50W of heat coming off this board. Enclosure will be an issue, especially if you're trying to make it small. I assume some sort of simple but regulated power supply? More heat? I still like the CCS plate loads, at least on the first two stages. The IXYS devices are small, cheap. and easy to use, On the first two stages you wouldn't even need heat sinks.
kevin gilmore Posted March 16, 2012 Report Posted March 16, 2012 (edited) The plate resistors will be on the top side of the board with the tubes. All the rest of the stuff is going to be on the bottom of the board. Would mount the same way the T2 amp board does. Edited March 16, 2012 by kevin gilmore
arnaud Posted March 17, 2012 Report Posted March 17, 2012 (edited) When I see how prolific you guys are, I am just wondering if the amp makers like Stax are doing anywhere near the same amount of R&D? For one, it seems like there's a large collective brainstorming going on constantly in such threads. Can't someone just bring these solutions to the masses (e.g. non E.E. / soldering beware people like me) for a profit or this just spoils the fun? Edited March 17, 2012 by arnaud
n3rdling Posted March 17, 2012 Report Posted March 17, 2012 The PA89 looks really interesting. For the levels we'd run it at, wouldn't there be about 10% THD at 20kHz or am I looking at the wrong line?
kevin gilmore Posted March 17, 2012 Report Posted March 17, 2012 Measured power on the amp channel is 15 watts, so the 2 amp channels are 30 watts. i'm going to do a smaller simple regulation power supply board to go with it, basically an updated version of the original BH board with ixys as the current sources for the zeners. No one is really seriously going to build a 4 x pa89 thing. I've used them a lot in the past, and any mistake, and they blow up real easy. While an ultra simple design this would be a bad idea, and perform like ray's darkstar. No one really wants that.
Beefy Posted March 17, 2012 Report Posted March 17, 2012 Measured power on the amp channel is 15 watts, so the 2 amp channels are 30 watts. i'm going to do a smaller simple regulation power supply board to go with it, basically an updated version of the original BH board with ixys as the current sources for the zeners. I'm throwing money at the screen, but nothing is happening
spritzer Posted March 17, 2012 Author Report Posted March 17, 2012 The PA89 is more a joke but it certainly would work. File it with my tiny transformers and other such novelties. When I see how prolific you guys are, I am just wondering if the amp makers like Stax are doing anywhere near the same amount of R&D? For one, it seems like there's a large collective brainstorming going on constantly in such threads. Can't someone just bring these solutions to the masses (e.g. non E.E. / soldering beware people like me) for a profit or this just spoils the fun? Doing anything for money spoils it IMO but with Stax you have a limited number of employees who are probably not building amps in their spare time. In the late 60's Hayashi-san was very prolific and published numerous designs, some very much of team overkill. Then they diversified into other markets but I have no doubt that there are some truly inspired designs lurking in some backroom. Producing those might be problematic at best though... We on the other hand aren't bound by such concerns and can come up with truly crazy stuff using rare parts at will. Amps like the Bate aim to bring this to the masses but without somebody selling the PCB's and other necessary parts it is always a bit out of reach.
kevin gilmore Posted March 17, 2012 Report Posted March 17, 2012 (edited) power supply done, suitable for BATE and LL 7.8 x 6.12 inches, probably as small as i can get it. http://gilmore.chem....u/batepower.jpg This power supply also works if you are retrofitting an ESX, or want to build a point to point ESX. Finally finished the preamp board, tested all the audio stuff, and it measures below the noise level of my equipment. Will listen to it later, but that one seems now done too. Edited March 17, 2012 by kevin gilmore
n_maher Posted March 17, 2012 Report Posted March 17, 2012 Hmmm this thread is now of great interest to me.
morphsci Posted March 17, 2012 Report Posted March 17, 2012 Yep, I thought of you when I read Kevin's post .
guzziguy Posted March 17, 2012 Report Posted March 17, 2012 Kevin, I have a layout question. The anodes of the two large (in diameter) electrolytic capacitors have square pads whereas the anodes or all smaller electrolytic capacitors have round pads. Is there a reason for this or is it just an oversight in the layout?
spritzer Posted March 17, 2012 Author Report Posted March 17, 2012 While the design works perfectly in a ES-1, I doubt it will fit any of them. Max 10cm or so on either side of those massive transformers and that's the only space available in the psu box.
kevin gilmore Posted March 17, 2012 Report Posted March 17, 2012 (edited) It should certainly fit in neilvg's unit Its about time he got that thing fixed, he paid enough for it. All the ESX things have completely unregulated power supplies and no bias supply for the output tubes plus the electrostatic bias is the wrong voltage. You could always mount the power supply on the top of the box... The heatsinks are grounded. The square pads were that way on the kgsshv power supply, and this is just a cut and paste from it. Only took me about 1.5 hours to do this one. I can make the other ones square... wait a minute or two. I'm doubling up on the unreg and reg load resistors to cut the power and decrease the voltage across them to keep them within spec. The pappy van-winkle and the cuban are certainly helping. minute is over Edited March 17, 2012 by kevin gilmore
guzziguy Posted March 17, 2012 Report Posted March 17, 2012 (edited) You missed one. I just wanted to know if there was a technical reason. I wasn't trying to point out errors. Edited March 17, 2012 by guzziguy
kevin gilmore Posted March 17, 2012 Report Posted March 17, 2012 (edited) OK, now you are getting picky. Seriously, i want this one perfect before we make boards, and the more eyes (i.e group think) the better. Birgir is the "thought leader" on the project. I did make one mistake on the preamp board... But it works anyway And it works mighty well too. At least prototype runs are cheap these days. schematic http://gilmore.chem....u/batepower.pdf (yep more cut and paste) There are some 680uf/500V caps in stock at mouser, a little extra headroom always a good idea. not cheap though. http://www.mouser.com/ProductDetail/Kemet/ALC10A681DL500/?qs=sGAEpiMZZMukHu%252bjC5l7YSuaTY1g5Qh1YkGGiaJm46w%3d Edited March 17, 2012 by kevin gilmore
spritzer Posted March 17, 2012 Author Report Posted March 17, 2012 Hmmm... now I need to look for a robe and start leading people in earnest...
guzziguy Posted March 17, 2012 Report Posted March 17, 2012 Don't forget a pointed hat to go with the robe.
spritzer Posted March 17, 2012 Author Report Posted March 17, 2012 But... but... then I can't use my Stax....
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