Can I used power BJTs in a BA-2 configuration? I would just adjust the TL431 for @1.4 volts for biasing into class B and use the BA-3 as the driver.
naah ......... for class B bjt you need different biasing methods ; in short - sensing htsnk temperature , to avoid gray smoke
OK, I've given the superreg 24hrs with the BA-3. Here's what I think:
Superreg has more detail than the LM317/337 psu. This is the most obvious difference. With the volume control maxed out on the BA-3/F5 I could hear a bit of noise from a few feet away from my 91DB efficient speakers. Quiet but there. With the Superreg I have to put my ear up to tweeter to hear anything. So perhaps the noise floor has dropped a bit.
Overall it is an improvement...small but noticeable. Makes the system a little more lively and imaging seems locked in a bit better. It seems to have lost a little tonal density...sounds a little thinner, just a little. This may be due to tighter bass or less bass bloom. "Clean" is the word I would use. Seems like some of the bass and "slam" is returning as it runs in. It seems to be loosening up a little.
Also, I was running 30V rails w/the LM317/337 combo. Now I am running 25V rails due to the greater dropout of the superreg (5V or greater is recommended). I am guessing this is kind of a step backwards (I assume more rail voltage is better) then a step forwards with the superreg.
Should all you guys w/LM317/337 regs on your BA-3 ditch them for the superreg? It's your call. I am happy, glad I did it.
If I swap a transformer from one project to another I could have enough overhead voltage to try a shunt in the BA-3... I wonder, that would be interesting... 🙂
http://www.diyaudio.com/forums/pass...more-boring-making-thread-21.html#post1466712
while we are there .........
......
(talking about ........ once I mounted watering can instead of TV antenna on the roof , naturally with antenna cable connected to it ........ just to tease my neighbors .......... they have strange look few days ............)
With preamp off, should I be able to turn P1 P2 resistance to zero?
Negative rail, lowest on trimmer measures 100ohms. I ran into issue, neg rail
On power up measures -24v the becomes -5v. I pulled the board out and going through
All the part vaues and shorts.
P1 and P2 are 1K, Im using fairchild for Q3 Q4
Negative rail, lowest on trimmer measures 100ohms. I ran into issue, neg rail
On power up measures -24v the becomes -5v. I pulled the board out and going through
All the part vaues and shorts.
P1 and P2 are 1K, Im using fairchild for Q3 Q4
Sorry, measured wrong end of resistor
What resistance should I measure at R3 if P3 100ohm is set midway?
What resistance should I measure at R3 if P3 100ohm is set midway?
R3 and r4 should have same resistance across them when p3 is midway.
What are you using for a psu? If you dont have 24v positive and 24v neg out of the psu you have issues. Dont hook it up to the board.
yes, picked up a shunt type dual psu board on ebay
Its working now, still not sure what the problem was on the negative rail
Reason I was asking about P3, I accidently adjusted it thinking it was P2
and wanted to get it back to mid point
Thx
Its working now, still not sure what the problem was on the negative rail
Reason I was asking about P3, I accidently adjusted it thinking it was P2
and wanted to get it back to mid point
Thx
How many turn pot is it? Turn it all the way in one direction and the go back 12.5 turns if it's a 25-turn pot. It will be close enough to make no difference.
Butter fingers, I shorted R10 while power on, would that kill Q3 or Q4?
I measure Q3 Q4 2 pins measure 560ohms and other 2 infinite resistance
Doesnt seem shorted
I measure Q3 Q4 2 pins measure 560ohms and other 2 infinite resistance
Doesnt seem shorted
Iam no expert but I would look at the mosfets first...then jfets then trimpots. The electro caps could be damaged too. Resistors should be ok. I shorted a thermistor on my f5. Everything was fine but the trimpots...took me forever to figure out. Test the trimpots by locating the resistor effected by them and seeing if the resistance across the trimpot changes when the pot is turned.
I borrowed dual psu bench supply, circuit survived, each channel draws about 56mA at 24V
The psu board I have is messed up on the neg. Rail
Will get another psu board going
Thx
The psu board I have is messed up on the neg. Rail
Will get another psu board going
Thx
What shunt reg did you get off ebay? Ive heard some bad things about the ebay shunt regs.
What voltage transformer are you using? A lm317/337 setup works, is hard to mess up and is cheap. Iam using a superreg in mine, sounds good but is a little more complicated to set up. And more expensive.
This one, only because you asked 🙂
I know many dont like to use ebay stuff.
http://www.ebay.com/itm/Class-A-Par..._Audio_Amplifiers_Preamps&hash=item4610fcc9d8
This was cheap enough to give a try. The schematic is not same as
Parts on the pcb, neg. Rail uses lm337 and some other parts,
Different from schematic. Problem with this board, they use hard to find
Toshiba parts.
yup, I have a twisted pear 317/337 probably will stuff and and use
$15 shipped! Too good to be true. Probably full of fake mosfets and bad caps. Ive got nothing against chinese ebay stuff...as long as its not ripping off someone elses design. But this thing is too cheap to make any sense at all.
Ive read good things about the Salas shunt. But shunts can be bad or good depending on the design.