BA3 preamp hiss

fwt1712

Member
2012-07-22 10:02 am
I have got my BA3 preamp up and running (into peter daniels gainclone and then original spendor sa1 speakers) and am very happy with the music it is producing - way better than anything else I have used (audio synthesis passion passive mainly). It has added way more clarity, depth, power, precision but it is a bit hissy(er) than I would like. Basically I can hear a hiss/whooshy sound from a meter when not playing music and occasionally on very quiet sections. I have followed the build guide and used what I think are good bits i.e. all dale rn60s, mundorf evo oil output caps etc, alps blue 50k pot and tubecad input selector and ps19 bipolar supply. It powers up nicely with no thumps or bumps etc. and is biased pretty much bang on 1v as specced. I am just a bit perplexed at what I think is just a bit too much hiss. It doesn't vary with change of volume control from min to max (with no music of course) and even at max volume there is only the slightest hint of hum - and none below it. Any ideas on where to look - or even confirmation that this is to be expected with a no feedback design would be appreciated.

thanks in advance,
Nigel.
 
I used that PS in my second BA3 pre. VERY worthy, mine is dead silent. 6L6 used the previous model in his build. Sorry guys, problem is elsewhere.

Russellc

worth trying , in case that any of LM chips is dude

and believe me , plenty of them around

regarding LM vs. decent shunt reg .......... to each his own

as always , YMMAMV
 
worth trying , in case that any of LM chips is dude

and believe me , plenty of them around

regarding LM vs. decent shunt reg .......... to each his own

as always , YMMAMV

Oh no, you would be right as to superiority of shunt reg...well known fact. I'm just saying that particular power supply isnt doomed out of the box.

I have a populated mezmorize and hyponotize board I would like to use as such...also your shunty which is my next project. ( will try to get it working before tackling the Pumpkin, all in good time ) May be missing the smarts to implement in BA3, but for now the 317 power supply works fine. Maybe he should try different pieces of those parts.

My other BA3 FE has a power supply built on Peter Daniels board, I forget which regulator it uses...

Russellc