wink Posted January 20, 2013 Report Share Posted January 20, 2013 (edited) "I don't think there ever was any Germanium sand that could handle 1500V..."That's why you need to run about 10 devices in series.......":) My plan is for a spud electrostatic amp with just two triodes and DHT's at that. I know ETF.12 had a competition along these lines but I'm going to be far stricter to myself. No push-pull, current sources, parallel tubes etc. Just transformer, triode and transformer... "Team Overkill lives.....An instance when less is moar.. Edited January 20, 2013 by wink Quote Link to comment Share on other sites More sharing options...
spritzer Posted January 20, 2013 Author Report Share Posted January 20, 2013 We are indeed alive and well, just sidetracked by some other projects. I might also add a TVC to it for MOAR transformers... Quote Link to comment Share on other sites More sharing options...
Victor Chew Posted January 21, 2013 Report Share Posted January 21, 2013 (edited) I'm interested why you guys have decided to do a 300B electrostat amp after all. From reading old posts on Headfi I got the impression that it would be a poor idea.I have always loved the sound from the 300Bs. With an external transformer box it didn't sound quite as clear (Border patrol pre/power with my illsions); but there is to still something about it that encapsulates me even after it was sold. Edited January 21, 2013 by Victor Chew Quote Link to comment Share on other sites More sharing options...
Pirx Posted January 21, 2013 Report Share Posted January 21, 2013 I have always loved the sound from the 300Bs. With an external transformer box it didn't sound quite as clear (Border patrol pre/power with my illsions); but there is to still something about it that encapsulates me even after it was sold. That is the reason I am testing 4x6BG4 (6C4C) in my new project for STAX. It is doable, it can play loud enough with magic of DHT's. But work is still in progress. Quote Link to comment Share on other sites More sharing options...
Victor Chew Posted January 21, 2013 Report Share Posted January 21, 2013 What is the hv voltage you intend to use to feed the output tubes? Assuming you are using output trans, what ratio would you be using? Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted January 21, 2013 Report Share Posted January 21, 2013 I might also add a TVC to it for MOAR transformers... I might have one for sale if you are interested... Quote Link to comment Share on other sites More sharing options...
Pirx Posted January 21, 2013 Report Share Posted January 21, 2013 What is the hv voltage you intend to use to feed the output tubes? Assuming you are using output trans, what ratio would you be using? Tubes are choke loaded and Uak=300 V, Ia= 30-40 mA. Quote Link to comment Share on other sites More sharing options...
spritzer Posted January 21, 2013 Author Report Share Posted January 21, 2013 The 6C4C is at least cheap so the voltage limitation is less of an issue.I might have one for sale if you are interested...You know me, I have very little willpower when it comes to buying parts... Do these have a 6db gain tap on the primary? Quote Link to comment Share on other sites More sharing options...
Pirx Posted January 21, 2013 Report Share Posted January 21, 2013 The 6C4C is at least cheap so the voltage limitation is less of an issue. What do you mean? Choke loaded triode doesn't need HV over 300 V, so low max Uak of 6C4C (360 V) is not limitation if you want to drive STAX. That is my opinion. But I am not sure if I have understood you correctly (my English suffer, sorry). Quote Link to comment Share on other sites More sharing options...
spritzer Posted January 21, 2013 Author Report Share Posted January 21, 2013 Not a whole lot of headroom with 300V. Quote Link to comment Share on other sites More sharing options...
Pirx Posted January 21, 2013 Report Share Posted January 21, 2013 Not a whole lot of headroom with 300V. My old T1 plays enough loud, power stage with 6C4C choke loaded plays louder. I don't need more voltage swing. I think many of us don't need as long as they have healthy hearing. Of course it is my opinion Quote Link to comment Share on other sites More sharing options...
spritzer Posted January 21, 2013 Author Report Share Posted January 21, 2013 It's not really about listening at insane levels. We were well aware that an amp like the KGSSHV and T2DIY can and will burn up a Stax transducer if it were ever to see the full force of the output. Not likely to happen unless somebody were to feed it from a high gain preamp but it is something to think about. That said the amp is then just idling at normal levels so there are clear benefits to using crazy voltage levels. Quote Link to comment Share on other sites More sharing options...
Pirx Posted January 21, 2013 Report Share Posted January 21, 2013 It's not really about listening at insane levels. We were well aware that an amp like the KGSSHV and T2DIY can and will burn up a Stax transducer if it were ever to see the full force of the output. Not likely to happen unless somebody were to feed it from a high gain preamp but it is something to think about. That said the amp is then just idling at normal levels so there are clear benefits to using crazy voltage levels. True, true, I agree, but what is normal levels? I am going to make some measurements of max swing from 6C4C with chokes, when I finish prototype (testing different types of drivers). Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted January 21, 2013 Report Share Posted January 21, 2013 You know me, I have very little willpower when it comes to buying parts... Do these have a 6db gain tap on the primary? Â I think so. It's not an off-the-shelf part, so I'll have to check. Always up for trades as well Quote Link to comment Share on other sites More sharing options...
spritzer Posted January 21, 2013 Author Report Share Posted January 21, 2013 Why am I not surprised it is custom. I'm always up for some trading as well.True, true, I agree, but what is normal levels? I am going to make some measurements of max swing from 6C4C with chokes, when I finish prototype (testing different types of drivers).Well that's where it gets tricky as this varies quite a bit. The spec for Stax states the 100Vrms point but how they get that figure is unknown. Quote Link to comment Share on other sites More sharing options...
dennis h Posted March 9, 2013 Report Share Posted March 9, 2013 So how is the Volksamp project coming ? dennis h Quote Link to comment Share on other sites More sharing options...
spritzer Posted March 9, 2013 Author Report Share Posted March 9, 2013 We are working on other things but I've built a prototype that I'm quite happy with. I just need to sit down and draw up a PCB and find a suitable transformer. Quote Link to comment Share on other sites More sharing options...
dennis h Posted March 10, 2013 Report Share Posted March 10, 2013 Thanks for the progress report. I am not ready yet, am building jigs to make own phones and don't have a driver to test yet, let alone a matched pair.. dennis h Quote Link to comment Share on other sites More sharing options...
spritzer Posted May 14, 2013 Author Report Share Posted May 14, 2013 Now here is something really different I got in the post today, a 12V-260V DC-DC switcher.   Very small and no problem going bipolar or even stacked for super small electrostatic amps. There is one I've already drawn up that will be rather cool.. Quote Link to comment Share on other sites More sharing options...
n3rdling Posted May 14, 2013 Report Share Posted May 14, 2013 Bias line for NB Stax Quote Link to comment Share on other sites More sharing options...
spritzer Posted May 15, 2013 Author Report Share Posted May 15, 2013 That would work but 20W is a bit too much for that use.  What about two of these stacked (+260/+520V) driving a fully balanced GES. The tubes are run off the 12Vdc supply so the amp could be tiny, 10" by 10" and 1U tall. Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 6, 2013 Author Report Share Posted June 6, 2013 Now something to use with the mini switcher above, a subminiature tube electrostatic amp.   The pcb is less than 120*90mm for both channels and it is fully balanced from input to output. Only one B+ for both given the voltage constraints of these tubes so limited voltage swing but who cares... it will look cool. Quote Link to comment Share on other sites More sharing options...
Torpedo Posted June 6, 2013 Report Share Posted June 6, 2013 You may wish to change the "All Tiode..." inscription in the center of the board Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 6, 2013 Author Report Share Posted June 6, 2013 (edited) Crap!!!!  Nahhh... just kidding. The production version is a bit different. Edited June 6, 2013 by spritzer Quote Link to comment Share on other sites More sharing options...
Torpedo Posted June 6, 2013 Report Share Posted June 6, 2013 Hehehehe, I was going to say that "Triode" would be more adequate than "crap", but it would make for a funny motto. Quote Link to comment Share on other sites More sharing options...
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