"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, 201313 yr by wink

We are indeed alive and well, just sidetracked by some other projects. I might also add a TVC to it for MOAR transformers...

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, 201313 yr by Victor Chew

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.

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? 

I might also add a TVC to it for MOAR transformers...

I might have one for sale if you are interested...

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.

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?

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).

Not a whole lot of headroom with 300V.

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

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.

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).

You know me, I have very little willpower when it comes to buying parts... Do these have a 6db gain tap on the primary?

 

I think so. It's not an off-the-shelf part, so I'll have to check. Always up for trades as well

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.

So how is the Volksamp project coming ?

dennis h

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. 

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

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.. 

Bias line for NB Stax

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. 

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. 

You may wish to change the "All Tiode..." inscription in the center of the board

Crap!!!!

 

Nahhh... just kidding.  The production version is a bit different. 

Edited June 6, 201313 yr by spritzer

Hehehehe, I was going to say that "Triode" would be more adequate than "crap", but it would make for a funny motto.