-
Posts
91 -
Joined
-
Last visited
Content Type
Profiles
Forums
Events
Posts posted by Pirx
-
-
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.
-
...and it's pretty much done.
......Runs very hot, front panel at 60°C after an hour. Hardly surprising given 0.8A@12V times four plus the regulators. I need some new resistors...
Nice build and it should sound very warm I guess Arctic version?
-
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.
-
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'm working on a few Stax DHT amps ....
I would like to know more about it Would you be so kind and tell us details?
-
I've bought 14 transformers (at different times) to www.toroidy.pl and I am happy with their performance.
I've bought about 12 audio class transformers from www.toroidy.pl and everything is fine - cold, quiet, efficient. I recommend.
-
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).
-
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
-
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).
-
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.
-
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.
-
My latest DIY electrostatic amplifier. It is built entirely on information in this and “Now for something different...” topics.
Looks very hot and nice, give us some night shots, please
-
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
-
Heat will be an issues but all the hot bits are on top of the chassis and I'm in Iceland after all...
I realized you are making very nice sounding oven
Which schematic, from hundreds in this thread, is the right for your Megatron?
-
Here is something indeed a bit different...
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.4mA seems about right but I'm with Nate here, the terminals on these transformers are open so they are easy to short. If something like that occurred then who knows what happened internally.
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.I wonder if some past event didn't cause damage to the trafo (before the current ownership) and it's now no longer capable of performing properly even under the best of circumstances?
-
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).output dc on the tubes should be close to 0. 150v is not right
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).Too much current through the tubes would be my guess.
But I have discovered this time there was not +320 V but only +308 V. That amp drives me crazy ;-)
-
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
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.
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.
I have no idea if it's right for T1.If they are 20% high, then what you really have isthe transformer wired for 200v running on 240v.
But I have SRM-006 schematic and there are very similar voltages: 250 V, 270 V, 6,3 V.
-
Yes, from Wiktor.
Were these on ebay from wiktor or rotkiw ?
There are only 2 tubes. Trafo is set to 240 V. In my opinion discoloration and temperature doesn't look good.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.
I have schematic from SRM-006 only, but I am not sure if it is the same or similar to T1
There is no hum or noise in headphones, amplifier seems to work good.
-
Hello Everyone
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 My previous system was SRM-727 and SR-507 and it wasn't so good.
BIAS for Sennheiser Orpheus
in Headphone Amplification
Posted · Edited by Pirx
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