[macm75]

I just built an amp for a pair of Stax SR-303's that I'm still waiting for.
In the meantime, I'd like to test the amp with a pair of old SR-30's (electret) I have laying around.
Will the pinouts to the SR-30 match the SR-303's and will the SR-30 accept 580VDC bias?
The SR-30 is 5 pin so I assume all Stax 5 pinners are "pro bias" 580V but I want to check so I do not blow the stuffins out the the SR-30's.
Thank You.

 

[MaloS]

You...built....one? You are a genius.

Although I am quite certain that 5 pins imply pro bias.

 

[Carl]

The electrets are 100% intercompatible with both 6 pin (230v bias) and 5 pin (580v bias) outputs. The bias pin is just a dummy, its not connected to anything. My SR50s work a treat with my electrostatic rig.


Tell me more about your amp. I'm [slowly] designing my own 'stat amp, so it's always good to hear other people's experiences.

 

[macm75]

Quote:

Originally Posted by Carl /img/forum/go_quote.gif Tell me more about your amp. I'm [slowly] designing my own 'stat amp, so it's always good to hear other people's experiences.

I chose the Andrea Ciuffoli design 6SL7-6BX7 amp simply because I had all the parts except for OPT's. I'm also a big SE fan so it fits my tastes.
http://www.audiodesignguide.com/my/stax_amp2.html
I bought the Lundahl 25mA LL1660 version so I can try other tubes like 45's and 2A3's. It's built it per Andrea's spec to start out.
I'm not a designer - I do build lots of tube amps though. When I get the 303's and the connector, I will certainly post the work in the DIY section. Unfortunately, I have never heard Stax electrostatics and have no access to a Stax mfg'd amp so I have no "Stax basis for comparison".

 

[Carl]

Quote:

Originally Posted by macm75 /img/forum/go_quote.gif I chose the Andrea Ciuffoli design 6SL7-6BX7 amp simply because I had all the parts except for OPT's. I'm also a big SE fan so it fits my tastes. http://www.audiodesignguide.com/my/stax_amp2.html

Ah yes, I know that design. I'm quite fond of his choice of 6BX7s, although if it was me, I'd have gone for a pair of 6AH4s instead. It's a good first amp for electrostatics, anyway.

Quote:

I bought the Lundahl 25mA LL1660 version so I can try other tubes like 45's and 2A3's. It's built it per Andrea's spec to start out.

The 10/801A/841 would be a better choice for electrostatics than than 24/2A3 are. On top of the higher peak voltage handling, they also have that 'thoriated glow' that oxide cathode tubes lack. Too late now though, I guess.

Quote:

I'm not a designer - I do build lots of tube amps though. When I get the 303's and the connector, I will certainly post the work in the DIY section. Unfortunately, I have never heard Stax electrostatics and have no access to a Stax mfg'd amp so I have no "Stax basis for comparison".

Well, Stax hasn't made all-tube amps for electrostatic headphones since the late 60s, so your design will sound different from their current offerings no matter what you do.

I'll give you a tip though, the Lambda series of headphones (of which the 303 is one) are very demanding of the bass performance of the power supply. I fear that the LCLC filter in Andrea's amp isn't really suited for the job, not that it will sound bad, just that the lower regesters will lack the control and authority they could potentially have. My designs all use super-shunts.

 

[macm75]

Quote:

Originally Posted by Carl /img/forum/go_quote.gif The 10/801A/841 would be a better choice for electrostatics than than 24/2A3 are. On top of the higher peak voltage handling, they also have that 'thoriated glow' that oxide cathode tubes lack. Too late now though, I guess. I'll give you a tip though, the Lambda series of headphones (of which the 303 is one) are very demanding of the bass performance of the power supply. I fear that the LCLC filter in Andrea's amp isn't really suited for the job, not that it will sound bad, just that the lower regesters will lack the control and authority they could potentially have. My designs all use super-shunts.

Carl, concerning the 10's, I have them to try - globes and ST's I obviously just have to be more concerned with heater DC regulation here.
All is possible with the amp at this stage - it's layed out on a huge piece of plywood. I'll be playing with tubes, caps, PS until I get my fav sound.
Thanks for the advise, I'll most likely come back for more