For the moment, I will have to enter the KGSShv unbalanced (DAC asymetrical outputs only). Is there à way to go balanced before the quad pot : there are some active module with opamps but I'm à bit afraid of quality lost. Is there any advice ?

Yes, DRV134. http://sjostromaudio.com/pages/ . At unbalanced in my B22, I was not able to get the DC offset down to zero. Infact it was way off. These days, I believe you can get many other alterative devices.

That sounds like a pain. I would just leave the balanced XLR connectors. Why don't you just use an XLR to SE cable?

The DRV134 is a POS and causes far more issues than the slight loss you get with the natural phase splitting in the HV.  Just make a RCA-XLR cable with the - grounded. 

Justin, any news on the 2SA1486's you were selling?

By the way, thank you for the SR-009

Edited January 10, 201313 yr by eggil

Justin, any news on the 2SA1486's you were selling?

By the way, thank you for the SR-009

 

i posted in the T2 thread.  i can get a good price on 'real' ones and i can get a better price on 'possibly real' ones.  i'm checking them out first.  most likely they will be fakes and i'll move on.

Thank you Justin.

Spritzer, did you use a latching switch in your build?

Edited January 14, 201313 yr by eggil

Yup, I always use latching switches on my amps. I like the simplicity of mechanical things...

Are you still using the latching switches from that computer case place Birgir? If not, what?

Amp board #1 powered on without any problems.

Now to stuff board #2.

Edited January 14, 201313 yr by eggil

Good job.

Congrats!

I really wish more people would try doing this instead of describing how liquid their amplifier sounds

I am doing my build while living in the UK, but will move back to the US in a few years.  I am finalizing my transformer order (Sumr) and was considering getting a dual primary winding.  Is there any downside to having the dual windings?

Not that I am aware of. I always order dual primaries for any transformer (custom or other).

Edited January 15, 201313 yr by Pars

I always get dual windings as well. I can't see any downside to it.

Are you still using the latching switches from that computer case place Birgir? If not, what?

Well I bought a pile from them so I still have some but I also bought 50 more from Alibaba. I might have a problem with stockpiling stuff.... I also just ordered some PCB's for these switches to make them easier to use. Built in spot for a resistor to drop DC voltage higher than 12V etc.

Now I'll get back to designing the PSU for the single ended Stax amp...

Edited January 15, 201313 yr by spritzer

Thanks.  That makes it easy...

I always order dual primaries for any transformer (custom or other).

I do that as well. Gives us the flexibility to change voltages. Perhaps 115v for the US and 230v for the UK.

Edited January 15, 201313 yr by Victor Chew

The only downside to dual primaries is cost.

Birgir, how are you implementing the latching switches? I thought that most of these weren't capable of switching the voltage and/or current levels that we need them to. Or am I just over thinking this?

[edit]I just looked at the specs of one of the 22mm Bulgin latching switches, clearly I'm wrong since they're rated for 250VAC/5A which should be sufficient on the primary side of most headphone amps.

Spritzer, will you any boards for sale for the latching switches?

Most of these switches can indeed handle 5A/250VAC but sometimes you have to track down the manufacturer and the actual spec sheets.

 

Spritzer, will you any boards for sale for the latching switches?

Sure, I bought 100 of them...    They were on the expensive side due to the routing required but it wasn't too bad.  I also have pcb's for the Alpha pot, pots too and the teflon Stax sockets should anybody need them. 

I'd like to buy 3 of each (PCB's) if you don't mind.

Edited January 15, 201313 yr by eggil

Is the NTE2588 an acceptable substitute for the Toshiba 2SC4686A, which is near impossible to track down now....

 

I compared data sheets and they are very close, but there are some subtle differences, but it seems like the major specs match and physically they should fit... I think.

Example, the continuous collector current on the NTE is 30mA, the Toshiba is 50.

 

NTE2588 Data Sheet http://www.nteinc.com/specs/2500to2599/pdf/nte2588.pdf

2SC4686A Data Sheet http://www.mouser.com/ds/2/408/7834-30958.pdf

 

Of course if there is another alternative, this is the first I've found and investigated.

 

I'll be doing the same for the 2SA970 and 2SC1815 next...

I guess it was only a matter of time before Mouser sold out of their stock of 4000 4686a, shame it's been obsoleted by Toshiba

The best alternative would be the 2SC4686 which is the same part with a lower voltage rating.  Still in production last I heard. 

 

I'd like to buy 3 of each (PCB's) if you don't mind.

 

No problem.  The switch PCB's should be here in a week or two so drop me a line then.