I agree having built the BA-3 as a preamplifier and the LSK J-fet linestage. I much prefer the LSK. It just has more dynamics and quickness. I tend to use my B1 V2 mostly with my Firstwatt clones though. Nothing particular wrong using the BA-3 front end as a pre though, just there are better out there.
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Thanks, this is my first preamp build and i've set my sights on BA-3 for now, but i will probably come back and want to build one of the others in the future...
I've got a couple more questions for the wizards:
- In the original post of this thread, i notice you (6L6) tie the center taps of the secondaries to ground on the regulator. Is finding the correct ones just a matter of tying to together and checking whether the remaining give 40V or 0V?
- Whats a good alternative to the ps-12? I was looking at the ps-19 at glassware audio, but its out of stock. Is any old Ebay regulator using LM317/337 fine?
- Is 3A enough current rating for the AC switch? (i found a nice looking lighted one which didnt break the bank but its only 3A rated at 230V).
- Is anyone here able to convert the .dwg files for the galaxy 388 to sketchup format (and possibly back to dwg again once i've done the panel designs). I tried downloading freeCAD but got to the conclusion i would spend more time learning how to draw three holes in the front than actually building the preamp...
Thanks in advance!
I've got a couple more questions for the wizards:
- In the original post of this thread, i notice you (6L6) tie the center taps of the secondaries to ground on the regulator. Is finding the correct ones just a matter of tying to together and checking whether the remaining give 40V or 0V?
- Whats a good alternative to the ps-12? I was looking at the ps-19 at glassware audio, but its out of stock. Is any old Ebay regulator using LM317/337 fine?
- Is 3A enough current rating for the AC switch? (i found a nice looking lighted one which didnt break the bank but its only 3A rated at 230V).
- Is anyone here able to convert the .dwg files for the galaxy 388 to sketchup format (and possibly back to dwg again once i've done the panel designs). I tried downloading freeCAD but got to the conclusion i would spend more time learning how to draw three holes in the front than actually building the preamp...
Thanks in advance!
- see attachment and think a little
-LM317/337 is good enough as temporary solution , if you ask me ; later find some better drek (possibly shunt , which is my preference)
-probably yes , considering that you're going to make preamp , not something of Godzilla size
Attachments
well , try to formulate question little better .... I'm easy to be confused .. .... 
regarding xformer - , when you have two windings , which you want to make one center-tapped from , there are really just two successful options ( and two wrong ones)
choose right one , then connect CT to PSU GND , remaining two wires to diode bridge
it's certainly easier/more productive to read and look at adequate schematics and think , then to ask pretty trivial things
catch is - some trivial things are harder to explain than to understand
go here : Basic Car Audio Electronics , menu on right , chapter 89
regarding xformer - , when you have two windings , which you want to make one center-tapped from , there are really just two successful options ( and two wrong ones)
choose right one , then connect CT to PSU GND , remaining two wires to diode bridge
it's certainly easier/more productive to read and look at adequate schematics and think , then to ask pretty trivial things
catch is - some trivial things are harder to explain than to understand
go here : Basic Car Audio Electronics , menu on right , chapter 89
I have the BA-3 fed by a Jung supereg at 24V. Also have the Salas DCG3 and Jfet box and have built a B1.
My favorite is the Salas although the BA-3 is probably my 2nd favorite. BA-3 lacks a little in the dynamics department and the bass is a bit loose and the top end a bit soft. It's not super clean either. But it throws a big, diffuse soundstage. And the ability to play with P3 makes it very interesting. Also, it has far less gain than advertised.
I would say it's better suited to small scale music. Probably the price you pay for no feedback.
well , try to formulate question little better .... I'm easy to be confused .. ....
regarding xformer - , when you have two windings , which you want to make one center-tapped from , there are really just two successful options ( and two wrong ones)
choose right one , then connect CT to PSU GND , remaining two wires to diode bridge
it's certainly easier/more productive to read and look at adequate schematics and think , then to ask pretty trivial things
catch is - some trivial things are harder to explain than to understand
go here : Basic Car Audio Electronics , menu on right , chapter 89
Thanks ZM, that does answer the question, point duly noted and i will keep reading!
Well, i am happy for another build project, and it being my first preamp build i don't yet need to get the best of the best (who knows, it may actually be _my_ best), but overall it sounds like a pretty awesome little thing! I will just have to build the others later to compare... Plus all the fancy regulators - for now i will go with the twisted pear low voltage regulator and then i can upgrade later, as per suggestions.
In any case, i am sure it will blow my cambridge stream magic (yes thats currently my pre) out of the water.
Weekend work seems to be bearing fruits...magic smoke still inside...phew!!!...started biasing right channel...took about 30 turns on the 1K turnpots before the first digit moved on the MultiM...heart pounded like anything...but that was a good sight...started biasing on R10..R11... slowly and gradually set that up at 0.75V on both the resistors...funny thing is the reading across R12 reads 0V no matter whatever bias I set...either I have done everything amazingly correct or messed up something...The MOSFET's are warming up just fine..close to 41 degrees C....went through the forum that need to ensure there is DC offset before C3...I tried moving around a places...except if I out MultiM across C3, is when I see some reading...Need suggestion which is the best point to pick for DC offset setting...
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Picked them from RS delivers, will share the part numbers in evening once I am back at my desk
True.
But we don't want dc offset to dance with all those precious ac signals.
I think..