Pirx

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.

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.

Looks very hot and nice, give us some night shots, please

I was using moded 727 with 507 and it also worked very well. Thank Spritzer for this mod

I realized you are making very nice sounding oven Which schematic, from hundreds in this thread, is the right for your Megatron?

OMG, looks crazy Don't you think that eight EL34 with no holes around them are going to be too hot? Even when you put them on the top of the case there will be no air from bottom. I would worry about temp. of PCB inside the case, temp of capacitors etc ...

True. I got this amp for two weeks. I can always replace this trafo in the future. Thank you All for help and suggestions. P.S. Perfect reason to build my own amplifier

Yes, it is possible. Who knows what history is behind this amp.

Sorry, I wasn't clear. Every triode has two 33k resistors in series. 150 V is on one of them, that gives 150/33000 - more less 4,5 mA. Output is close to 0 V (flows around zero). I suspect, this is the way my amp should work. It is very strange to me but everything seems to be ok but temperature of trafo. I need to look around for another T1 and check it.

Measurements shows about 4,5 mA/triode (probing voltage drop on anode resistors = about 150 V). But I have discovered this time there was not +320 V but only +308 V. That amp drives me crazy ;-)

Thank you Spritzer, the schematic helps a lot Voltages in my T1 are very close to those from schematic. Schematic my T1 320 V 319 V 350 V 344 V 48 V 48 V I have no idea why this trafo is so hot, everything seems to be ok

Thank you for your interest, Kevin. After one hour of working I can read AC voltages: 251 V, 268 V and 6,25 V. I have no idea if it's right for T1. But I have SRM-006 schematic and there are very similar voltages: 250 V, 270 V, 6,3 V.