The BA-3 as preamp build guide

It all is becoming very commercial and tourist oriented and as such to find the "gem" is a little harder now, say pizza for example, as said above they are all good but for us in the area and of a certain age there are some which are just meh and to find the right one sometimes takes to go through long queues if not for like pilgrimage, there is the worldwide famous "Da Michele", the line is unbelievable, once you get through you have two options (unless something changed since I last managed to get there), Margherita and Marinara, sit, order, eat and leave, maybe 10-15 euros at the most for pizza and a beer or another beverage.

Now the new trend is "contemporary pizza", very long raising times like 48 hours, dough very light, the border looks like lips of average MILF Mrs Suzy, needless to say it is a little boring, I suffer from acid reflux and as such I appreciate food which is easier onto my digestive system but if I go for a pizza I am ready for the beating so to find a "classic" one is becoming a challenge, not that contemporary isn't good, anzi, it is very good, just different, let's say JBL off the '90s vs modern speakers ;-)

Coffee is like pizza, a science, the experienced coffee maker knows how much pressure to apply on the powder before stuffing it into the machine, he knows how to handle the mixture depending on temperature and humidity and, last but no least, they say the quality of the water in Napoli (which comes off a specific basin) contributes to both the taste of pizza dough and coffee and I do believe that because as much as you can use same recipe and workflow for both coffee and pizza at your own place you won't get the same thing.

Ok, such a sproloquio to state you have to come to here to have the real thing!!!
 
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Oh well, it is what it is, after a comparison with the F4 driven by the Audio Research SP9, an Adcom GFP-345 and the BA3 I can tell that BA3 is maybe maybe marginally louder than the SP9 so I left the combo SP9 + F4 whose sound is amazingly clean and to whom my ears have to bet used after listening to KT88, I have the BA3 open, thinking of checking voltages before and after the PSUs just for the sake of it and, on the mid term, to have it modded to balanced (gonna order another PCB and the MosFets if my guy feels like working onto it again).

To make up for it I got a bottle of Gin Mare and tonic water, somehow it will help swallow the pill...
 
Hello everybody, today I wanna dedicate some time at trying and figure if my BA3 works as it should, I removed the top lid and took some measures off the PSU board, on the output it started with 33VDC and after 10 minutes dropping to 31.x

Would you help me and tell where should I take voltage measures so I can eventually figure if it is working as it should and then move on?

Grazie


On the Sigma22 PSU I read about 45VAC on the input RED-RED/BLACK and 31.xVDC on the outputs both positive and negative and still slowly dropping.

What should I read and where on the BA3 board?


Sigma22-7954.jpg
BA3-7955.jpg
 
heck, I simply like everything Italian, except 2 things:

  • all sorts of Lilliput size brews disguised as coffee
  • wiring on old Fiats and Guzzis
  • French Inquisition

I'm allowing that coffee is matter of things personal - upbringing, habit and taste, but - well, only ZM's taste is Absolute

:clown:
...and SERIOUS RUST on 70s & 80s Lancia's, Alfa 2L coupe. Had one of each totally beyond economic repair when less than 3 years old.

:bomb::bomb::bomb:
 
Hi all, finally got around to doing the P3 adjustment on my BA-3 front end and it appears I have a problem in one channel. I'm not getting the same distortion pattern in the two channels.

In my left channel, P3 adjustments can not null out the H3 distortion, but can do so in my right channel... creating a pure H2 pattern if I wish (all performed in ARTA with a -9db 1k test signal). I've got screen shots of my two channels at what I believe are identical P3 positions attached...

Any thoughts?

I'm presuming its either a MOSFET or JFET matching problem?

Right Channel P3 Adjust 4.2.24.jpg Left Channel P3 adjust 4.2.24.jpg
 
Unfortunately I did the build in 2020 and then put the stereo (and all of my belongings) in storage to move out of the United States, so the details are hazy. I just got everything set back up in December and am getting the stereo in shape again. I'm pretty confident they're from the DIYaudio store, praxis or punkydawgs... I did some digging in the mailbox and found every part receipt except the JFETS. MOSFETS are indeed from praxis and I did order JFETS from punkydawgs, but a month before my other parts for the BA3.
 
Unfortunately I did the build in 2020 and then put the stereo (and all of my belongings) in storage to move out of the United States, so the details are hazy. I just got everything set back up in December and am getting the stereo in shape again. I'm pretty confident they're from the DIYaudio store, praxis or punkydawgs... I did some digging in the mailbox and found every part receipt except the JFETS. MOSFETS are indeed from praxis and I did order JFETS from punkydawgs, but a month before my other parts for the BA3.
Just wanted to correct my spelling/memory error... the MOSFETS are from prakit.
 
it can, at least partially, be difference in output mosfets xconductance, even if they're heavily degenerated

anyhow- listen for hour or two in mono and only if you can hear difference between channels, do something

if not, chill
And thanks ZM. I'll follow the advice... I was listening last night and liked the sound post P3 adjustment regardless. Didn't think to do the mono test. My mind wanted to hear a difference, but who knows in a stereo recording.

And I presume the "do something" part of that would just be to order and install a new pair of matched MOSFETS?