Erik Mandaville Posted December 28, 2003 Share Posted December 28, 2003 I'm pretty sure they are finished, now. What I have made is a monoblock pair of parallel-feed DRD 2A3s. I'm not sure if they should be called DRD Horus 2A3s, or parallel-feed DRDs, but guess it doesn't really matter. The only things left of the original Horus, are parts of the PSU, as well as the 12 ohm resistor on the AC ground lug to the chassis ground. I had accidentally left that out on one amp, and it was the source of the hum I was getting this evening. It is a very cheap and effective cure JFL used on his Horus amps. It's interesting to note that about 500VDC B+ is about what is needed to do this circuit;however, there is just about 265 volts across the tube. Fine for both NOS 2A3s and current production. I wish I could call this my own design, but I couldn't have arrived here without the hard work of JFL (and Doc B and others experimenting with parafeed outputs), and Jack Eliano. I posted some few hundred posts ago about how curious it might be to combine parafeeding with the DRD/Ultrapath circuit, and so far things sound good to me. Any thoughts on what it should be called? Honestly, I'm trying to think of something that gives credit to those who brought this circuit together. Maybe something as simple as DRD Horus 2A3 would work... Whatever, I guess that will get worked out later on. Just thought I would share this. It's been a bit of work to get things balanced out, and this circuit really seems better, clearer, and more transparent without the Horus grid choke on the 2A3. 'night. Quote Link to comment Share on other sites More sharing options...
Parrot Posted December 28, 2003 Share Posted December 28, 2003 I'd think of some nice name and skip the descriptive nomenclature. The details and circuit credits can be kept for a lengthier description elsewhere; they would bog down the name itself. Moondog doesn't mean anything, but it has a nice ring to it. Quote Link to comment Share on other sites More sharing options...
3dzapper Posted December 28, 2003 Share Posted December 28, 2003 Mandaville 2A3. Most of these circuits are reworks of other circuits named after the modifier. Like Welburn etc. So take credit where it is due. Rick Quote Link to comment Share on other sites More sharing options...
jt1stcav Posted December 28, 2003 Share Posted December 28, 2003 Ditto what Rick said. You can always credit the original designers in your reworked circuits of "your" amp, but you alone came up with this one design. Call it what it deserves to be called, the "Mandaville 2A3". Has a nice ring to it, doesn't it? Quote Link to comment Share on other sites More sharing options...
neo33 Posted December 28, 2003 Share Posted December 28, 2003 How about Mandaville EM 2A3! P.S. EM is short for Erik-Marie. Quote Link to comment Share on other sites More sharing options...
Tubinhard Posted December 28, 2003 Share Posted December 28, 2003 Mandeville PFDRD Quote Link to comment Share on other sites More sharing options...
NOSValves Posted December 29, 2003 Share Posted December 29, 2003 Eric, forget all the catch phrase name and just call them YOUR AMPS !! Craig Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 29, 2003 Share Posted December 29, 2003 Yeah, Eric Mandeville amps....or is it Erik Mandaville amps? Manda-amps, Mandahorus, Direct Mandaville Drive, Mandadogs..... Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted December 29, 2003 Share Posted December 29, 2003 XtremeDoggamandes Strong commercial possibilities here..... Tom Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted December 29, 2003 Author Share Posted December 29, 2003 These responses made me laugh!!! Thanks both for that and for the comments. I agree, Paul, Neo, Rick, Mike (LOL!),Tom, Dean (that 47 Labs Gaincard is cool!) --all of you. I tend to get wordy, sometimes to a fault, I think. I remember one time in Grad school, a fellow art student who was suppposed to provide an explanation of his sculpture during a formal Master's critique said, "I don't have say anthing about my work -- or call it anything. It all speaks for itself." Both Profs, present looked at one another, and then both said almsot at the same time, "Well you better say something or call it something, 'cuz right now we don't hear a damn thing!" God, that was funny at the time! As far as commercial possibilities, I don't know. Eliano shared the DRD/Ultrpath circuit in VTV, but indicated it isn't for commercial production. It was intended for interested DIYer types, only. But what's different, is of course the parallel feed output, so who knows. Somebody sure as heck should do this, though! 'Mandeville' with an 'e' after the 'd' was the original spelling, and changed when the old folks came to this country -- first from France, then Holland, I think. Thanks for the input. Maybe this is the amp I mentioned I wanted to make about 6 months ago -- and did it without really trying to do it. A few things just sort of fell into place and it happened. It works and sounds pretty good. Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted December 29, 2003 Share Posted December 29, 2003 Erik, Post a schematic, maybe I'll try to build a pale imitation. Leo has expressed a willingness to sell me his original Electra-print trannies from his 'dogs. It's not a para-feed deal, I know, but I might be able to get part-way there while I save up pennies for later. Which front-end tubes are you using. Tom Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted December 29, 2003 Author Share Posted December 29, 2003 Tom: The schematic wouldn't be a problem, but do you have the original one I did of my own version of the Horus? Substitute the entire DRD front end for that, as well as the series cathode resistors on the 2A3...take out the grid choke, etc. Maybe I should just redraw another schematic, right?! I think a DRD with Leo's transformers would be a great SET amp! Certainly would be cheaper than parafeed, which was quite a bit even without the cobalt on the OPTs. Yours most certainly wouldn't be a pale imitation, Mike. It would be a slightly different amplifier, and a very good one at that! Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 29, 2003 Share Posted December 29, 2003 "Yours most certainly wouldn't be a pale imitation, Mike. It would be a slightly different amplifier, and a very good one at that!" Uh...I think you mean Tom. My SET amp ain't even close, it uses a 6EA7 for a driver. Oh yes, the infamous write-up required for one's art project. Color and Design I hated the worst, she always wanted more damn paperwork than artwork. Art History it was expected. And at 18, it was rather boring. At 39, it's pretty interesting now! I could never put on paper that would corelate with the project, I hated that sh*t! Sculpture class. I hate people hoverin' over me when I do work, and the Teacher asked me about it. He said quite a bit of Artist's are the same way. He liked me, he gave a B for a semester that I only went to for about a week. Let's say I wasn't ready to go to community college yet. Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted December 29, 2003 Author Share Posted December 29, 2003 Thanks Mike, I mean Tom! I know, I know Mike -- I've done this once or twice with Kudret and Wolfram I think, too. Sheesh, only 41 and already going senile and (Marie says) deaf! Quote Link to comment Share on other sites More sharing options...
leok Posted December 29, 2003 Share Posted December 29, 2003 Erik, I'm catching up. Do you use one gain stage? What tube? Good to have someone do a DRD parafeed .. make the audio path as clean as possible. Nice going. Leo Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted December 29, 2003 Author Share Posted December 29, 2003 Leo: The driver is a single 6N1P with grids, plates, and cathodes paralleled. This front end is virtually identical (minus input cathode bypass capacitor)to the DRD, and the rest is essentially a DRD with parafeed output. The main work was getting the bias balanced out on the 2A3, which also functions as a voltage divider for the 6N1P plate choke. With 500VDC B+, all voltages are in series, and I'm running the 2A3s at about 265V, anode to cathode. The Welborne/Eliano DRD uses a bit more HT filtering than I have, and I may add another filter cap in the power supply. I also worked out things within the chassis in order to accommodate a large Ultrapath oil capacitor down the road... Tomorrow I want to try the NOS 2A3 Blackplates Marie got me for Christmas. The Golden Dragons that were in the Horus before these changes were made were truly much quieter than the Sovteks, which I think are great tubes. Mine just make quite a bit of noise, for some reason... Quote Link to comment Share on other sites More sharing options...
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