Pirx

JimL, Spritzer - I can't agree with you about chokes and electrostatic headphones. I build an amp with 6C4C as a power stage with big 100 H chokes. It worked very well. I couldn't measure any resonance in audio spectrum. I didn't finish it only because it was too big and heavy. It was build only as a prototype, so I can't prove now anything else.

JimL - thanks for explanations. My future projects will be something with DHT with chokes as a power stage. I have build one like this, but it was too big and heavy. I needed small small amp so changed topology and build small. Here is a pic of the last stage with DHT:

Dear Kevin The only thing I am saying is that my project is mine, I don't know what you have done and when and how. The second and the third stage is multiply by 4 in my amplifier and if you look at this, there is nothing special. Just two stages with CCS and simply NFB. The first stage is also simply and known. Is there anything hard to develop and design what could be called it is mine, yours, theirs etc ... ? I would not call this NFB "dual". Just four simply amplifier, each with its own NFB.

That amp had to be small and stronger tubes and higher voltages with CCS meant more temperature. Sometimes you need to make decision - to make amp that folks on forum will call "awesome" or amp that you need but it won't impress the others :-) I like listening with low volume level but I know that many people like high levels. My amp is not good for everyone but it is perfect for me and Lambda Pro. The others of my Stax'a headphones will have stronger and bigger amp in the future.

Thanks JimL, DefQon and wink for your posts. It is not state of art to make amplifiers with tubes like everyone around I know 6CG7/6FQ7 are better in last stage, but I have about 40 pieces of E80CC and lot's of 6H1P-EB. I love the way Tungsram E80CC looks like, only Tungsram's E80CC have holes in anode. You are right about limitations of voltage swing and deliver current to headphones. This helps me to keep volume on healthy levels I designed this amp to drive my Lambda Pro while I am working on my PC, and Lambda Pro are easy headphones to drive. With Lambda Pro max volume levels are still above levels I like listening to the music with pleasure. Stax SR-007 are harder to drive and volume level is to low then. I am going to build bigger amp for SR-007 in the near future. E80CC won't be in the last stage But 6CG7/6FQ7 and 6S4A won't be there too :-) JimL - I have absolutely no idea about Kevin Gilmore's topology, but in my opinion 3 stages like this can't be called anyone's topology. I ended in topology like this after many tries, it seems obvious to me, that many people could end their research with similar schematics.

I am afraid you can't drive your Beats with this amplifier. It was designed only to drive electrostatic headphones.

Hello My little amplifier for my Stax headphones. First stage is based on ECC82. One triode per channel as cathodyne phase inverter. The second stage is 6N1P-EW with CCS, and power stage is with E80CC with CCS too. It was designed to work with my PC to drive Lambda Pro. So output voltage is not so big 308 V peak-peak, but it is enough for Lambda Pro.

Sad true I had luck and bought two pairs with one Power Suply PS2. One pair plays bright and light with bass, and the other plays with more bass and impact, but little less highs. Sound signature is far away from my Stax earspeakers, and this is fantastic. My wife said "there is more music in them" (in Jecklin she meant). Good news is there are spares for them at: http://www.quad-musik.de/html/spares.html New foams are for 38 €, and one new driver is about 170 € (pair for 340 €). But there is none new cables, plugs or sockets for this old Electrostat Try to search www.ebay.de for Jecklin Float. Price is almost always too high http://www.ebay.de/itm/FLOAT-JECKLIN-PS2-BOX-HEADPHONES-HEADPHONE-ECLECTROSTAT-/171594963370?pt=FR_Image_son_Ecouteurs&hash=item27f3db59aa

Hello Chinsettawong I am your big fan since your first electrostatic headphones on http://www.diyaudio.com/ The whole driver is 9,32 mm thick and dimensions are 119x105 mm. The window with visible stator is 74x85 mm. The are dust covers, but different from those in Stax drivers. It is smooth and looks like mylar, but it is not. It is different plastic foil, very thin and delicate. It is very easy to damage them.

... and driver:

My "new" old way to look strange during listening to the music ... ;-) I have also made some mod, it helps with the reproduction of lower bass. It is nice that new set of foams is still produced, but still waiting for delivery. Energizer is model PS2 with four transformers inside.

I've also restored drivers from Gamma Pro. Only coating was lost, and now they work great but I have no idea how long they will do. New diaphragm in SR-3 sounds better than Gamma Pro with only new coating. I wonder if in 1968 year in SR-3 Stax used mylar or something else?

Hello I bought pair of SR-3 year ago. I knew they had failure, left driver was quiet, right driver was only little louder. After year I've decided to give them new life this spring. At the first I've discovered holes in diaphragm of the left driver as you can see in the picture. I decided to use 2um mylar to make new diaphragm for both drivers and self made coating with some antistatic spray+isopropanol. Now I am sitting with them and writing this post, they sound great, with good bass, with sweet and not sharp highs.

I wasn't sure how large should be this "ballast" resistor. Thanks Spritzer, I can always count on you

Hi I am going to build energizer for Orpheus and Stax with LL9202AM. For Stax I will copy PSU Bias from T1. I wonder if I can use the same kind of PSU from T1 for Orpheus (with lower voltage of course)? I think so, but it could be very expensive mistake if I am wrong ... Any advice? http://farm3.staticflickr.com/2891/9135996783_0911380a26_o.jpg

What about case when you charge stators coated with something high conductive and signal is put to graphene diaphragm? This could work, I think.

Nice build and it should sound very warm I guess Arctic version?

Forget it, LM2596 doesn't stabilizied very well under 600 mA, so I didn't even try 6C4C. Voltage in from 6,5 V to 7,5 V gave voltage out from 5,5 V to 5,8 V.

I am going to try LM2596 - 150 kHz DC-DC converter with 6C4C. I will let you know how it works (if it works at all).

I would like to know more about it Would you be so kind and tell us details?

I've bought about 12 audio class transformers from www.toroidy.pl and everything is fine - cold, quiet, efficient. I recommend.

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).

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

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).

Tubes are choke loaded and Uak=300 V, Ia= 30-40 mA.