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Pirx

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Posts posted by Pirx

  1. A thin sheet of graphene is highly conductive so it wouldn't work as an electrostatic.  Plenty of other ways to do it though. 

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

  2. 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).

    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.

  3. 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).

  4. 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).

  5. 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.

    post-3957-0-74688900-1358756203_thumb.jp

  6. Just finished the resistor mod on the 727. Spritzer was right; those little glued-on surface mount resistors were a pain; however, I was able to get them off without lifting a pad or burning anything.

    Pared with SR-407s, so far (really just buttoned up), less fatiguing at higher volumes, less euphoric-leaning, more focused; better layering. Still slightly rolled off up top, which I attribute (at least in part) to the Opus 21. Otherwise, detail out the wahzoo; clean and resolving; nicely musical.

     

    Running balanced out of Opus, more for the 5v out. Amp pot disabled, more for remote control. Still need to try other volume configurations. Good+ paring with the 407; smaller amp profile better fits my desktop space, which is why I went this route. Happy happy with the rig.

    K and B, really couldn't have done it without you guys.

    I was using moded 727 with 507 and it also worked very well.

    Thank Spritzer for this mod :dan:

  7. output dc on the tubes should be close to 0. 150v is not right

    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 undecided.gif but everything seems to be ok but temperature of trafo.

    I need to look around for another T1 and check it.

  8. That transformer should not look like that so first things first, change the tubes as they are a likely culprit. Second, check the actual socket wiring on the Stax voltage selector as it might be wrong.

    The SRM-006t is pretty much identical to the SRM-T1 but here is the schematic since I have it. Not the best scan but it will do.

    Thank you Spritzer, the schematic helps a lot beer.gif

    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 huh.png

  9. Thank you for your interest, Kevin.

    You need to measure the high voltage rails to know more.

    After one hour of working I can read AC voltages: 251 V, 268 V and 6,25 V.

    If they are 20% high, then what you really have is

    the transformer wired for 200v running on 240v.

    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.

  10. .

    Were these on ebay from wiktor or rotkiw ?

    Yes, from Wiktor rolleyes.gif

    There is some disturbing discoloration on that transformer, in my non-professional opinion. I would make sure that the amp is setup for the proper line voltage (assuming it's adjustable like other Stax amps) and after that get a known good set of cheap tubes to try in there. Could be that one of the 4 tubes is going bad and drawing more current than it should be. Otherwise, I don't know enough about that amp to be really helpful.

    There are only 2 tubes. Trafo is set to 240 V. In my opinion discoloration and temperature doesn't look good.

    I have schematic from SRM-006 only, but I am not sure if it is the same or similar to T1 rolleyes.gif

    There is no hum or noise in headphones, amplifier seems to work good.

  11. Hello Everyone rolleyes.gif

    This is my first post here. I have done some research about T1 troubles here and didn't find any topic about hot trafo.

    In my opinion this trafo is too hot but I don't have another SRM-T1 to check.

    I have removed tubes and then trafo is only warm - seems ok.

    Picture shows where I put temp sensor (blue wire).

    Did anyone had similar problems?

    P.S. I have just bought SR-Omega with Mk1 driver and SRM-T1 - amazing sound rolleyes.gif My previous system was SRM-727 and SR-507 and it wasn't so good.

    post-3957-0-92857400-1352883009_thumb.jp

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