Disregard last question about shorting the inputs. I found the answer in a previous post (893 or so).
My favorite vendor doesn't have 22R for R10 and R11, but 20R. Is there an issue using this value in my BA-3 as a preamp only?
It will be fine. Bias will be slightly higher, so be sure to calculate with the actual resistor value (voltage across resistor divided by resistor value).
You mean bias voltage? 1V across r10/11 would give you about 50ma. Which is good. How high you can bias will depend on your heat sinking. But 45-60ma is probably a good place to start.
Okay, I need some help with biasing. I have P1 and P2 dialed all the way CCW until they click. P3 is set at it's midpoint (12.5 turns).
Without doing anything to P1/P2, R11 and R10 are measuring just shy of 1.1V. The lowest I've been able to get the offset with a little bit of turning P1 and P2 is 0.5V. Thoughts?
I'm getting about 23.5V from the power supply board...
Without doing anything to P1/P2, R11 and R10 are measuring just shy of 1.1V. The lowest I've been able to get the offset with a little bit of turning P1 and P2 is 0.5V. Thoughts?
I'm getting about 23.5V from the power supply board...
Ugh. Never mind. I posted that last comment and then it occurred to me that the pots are probably like faucets and maybe I should start with them dialed all the way clockwise. Okay, trying again...
The target is 1.0v, so you've got some room to dial down the offset.
Tweak, twist, and frammus the pots until you have zero offset with the maximum bias. If that boas is, say, 0.9v or more, and the offset before the capacitor is close to zero, you are good to go.
Tweak, twist, and frammus the pots until you have zero offset with the maximum bias. If that boas is, say, 0.9v or more, and the offset before the capacitor is close to zero, you are good to go.
No, I mean the voltage (+/-) rail. It says something between 20 - 30 volts in the F5, but what's the ideal as a preamp/ gainstage?
Well, I'm thrilled to report that my BA3FE is up, running, and putting out sweet, sweet, music! Thanks to the good and patient guidance from all of you here on this thread, plus a healthy dose of luck, everything went smoothly once I managed to get the wiring figured out.
I must say that turning up the volume for the first time and hearing music come through the speakers via the BA3FE and the ACAs - components I had built myself - was a really special thrill. And it continues to be as I work my way through my vinyl collection, hearing old favorites again for the first time with this new setup.
Here are a couple pics - from the work bench to the system. Next project is the power supply upgrade for the ACAs, then to work toward replacing that Bellari with the Pearl 2, and then, eventually, the Aleph J 😀 which is to say you can consider another newbie hooked!
Special thanks to 6L6 for the build guide, McQuaide for helping me figure out how to wire the volume pot, and to the rest of you for encouragement and help along the way!
I must say that turning up the volume for the first time and hearing music come through the speakers via the BA3FE and the ACAs - components I had built myself - was a really special thrill. And it continues to be as I work my way through my vinyl collection, hearing old favorites again for the first time with this new setup.
Here are a couple pics - from the work bench to the system. Next project is the power supply upgrade for the ACAs, then to work toward replacing that Bellari with the Pearl 2, and then, eventually, the Aleph J 😀 which is to say you can consider another newbie hooked!
Special thanks to 6L6 for the build guide, McQuaide for helping me figure out how to wire the volume pot, and to the rest of you for encouragement and help along the way!
Attachments
Outstanding! Well done!! 
It's a great sounding circuit, I'm sure you'll love it for a long time.
It's a great sounding circuit, I'm sure you'll love it for a long time.
Beautiful! I know what you mean, hearing great sounds through something you built with your own hands.
Outstanding! Well done!!
It's a great sounding circuit, I'm sure you'll love it for a long time.
Thanks, guys!
first pre amp build. Is this the preamp build for the ACA ?
I finished my ACA mono's last year. I remember reading all the different recommendations for pre amps.
If I remember correctly the BA-3 was one of them. I just started another electronic class at our collage, This Instructor list of final projects to pass the class listed a PreAmp and a power supply as qualifying projects. 🙂
Thinking ahead for my Alfa J and F5 or F5 T on my bucket list. I remember reading the BA-3 and power supply in one big chassis and then switch boards as I move up the food chain. A little confusion to chose voltage to use reading (BA-3 Ampilfier Illustrater buid guide) 20v-32v. The illustrater guide said it will focus on the 32V
But then i read this in ( The BA-3 as a preamp build guide)
Any project needs to start with a good PSU - this is an Antek 20+20V shielded transformer, and 317/337 linear regulator PSU from Tubecad.com. (Model PS-12) Of course you could use the Super Regulator V2.2 from the diyAudio store. Super Regulator V2.2 - Power Supplies and Accessories - Circuit Boards Look to the support thread to see the changes for 24V operation. (I didn’t use the Super Reg as that particular PCB wasn’t available when I ordered all my stuff…)
So do I pick the 24v24V to get 32V for the amps that use the BA-3 Or pick the 20+20V mentioned above that I read in this build?
Putting together parts list. the transformer is a pricey item. If i need to buy two different ones then I wiil when that day comes. I found this trans former at Mouser it will be good all the way up to the F5 TURBO
1182U24 Hammond Manufacturing | Mouser
or do I get the ( Antek 20+20V shielded transformer, ) mentioned above ?.
can't wait to get back to building again, life happens it's been a long break.
I finished my ACA mono's last year. I remember reading all the different recommendations for pre amps.
If I remember correctly the BA-3 was one of them. I just started another electronic class at our collage, This Instructor list of final projects to pass the class listed a PreAmp and a power supply as qualifying projects. 🙂
Thinking ahead for my Alfa J and F5 or F5 T on my bucket list. I remember reading the BA-3 and power supply in one big chassis and then switch boards as I move up the food chain. A little confusion to chose voltage to use reading (BA-3 Ampilfier Illustrater buid guide) 20v-32v. The illustrater guide said it will focus on the 32V
But then i read this in ( The BA-3 as a preamp build guide)
Any project needs to start with a good PSU - this is an Antek 20+20V shielded transformer, and 317/337 linear regulator PSU from Tubecad.com. (Model PS-12) Of course you could use the Super Regulator V2.2 from the diyAudio store. Super Regulator V2.2 - Power Supplies and Accessories - Circuit Boards Look to the support thread to see the changes for 24V operation. (I didn’t use the Super Reg as that particular PCB wasn’t available when I ordered all my stuff…)
So do I pick the 24v24V to get 32V for the amps that use the BA-3 Or pick the 20+20V mentioned above that I read in this build?
Putting together parts list. the transformer is a pricey item. If i need to buy two different ones then I wiil when that day comes. I found this trans former at Mouser it will be good all the way up to the F5 TURBO
1182U24 Hammond Manufacturing | Mouser
or do I get the ( Antek 20+20V shielded transformer, ) mentioned above ?.
can't wait to get back to building again, life happens it's been a long break.
The BA-3 is a power amp. You can use the front-end topology of it for a preamp, which is (somewhat confusingly) known as the "BA-3 as a preamp".
The Aleph J and F5 will be happier on 24V-ish rails. That's usually done with a 18+18V transformer, but a 20+20V should work fine.
The BA-3 and F5-T will also be happy with 24V-ish rails -- but they can take advantage of higher rails.
I'm not as familiar with the BA-3 as a preamp, but I can't imagine it needs more than 24V-ish rails.
So you could certainly start with 24V-ish and build all the amps (and the preamp), and then move up to 32V-ish if you find you need more oomph from one of the "big boys" (BA-3 or F5-T).
The Aleph J and F5 will be happier on 24V-ish rails. That's usually done with a 18+18V transformer, but a 20+20V should work fine.
The BA-3 and F5-T will also be happy with 24V-ish rails -- but they can take advantage of higher rails.
I'm not as familiar with the BA-3 as a preamp, but I can't imagine it needs more than 24V-ish rails.
So you could certainly start with 24V-ish and build all the amps (and the preamp), and then move up to 32V-ish if you find you need more oomph from one of the "big boys" (BA-3 or F5-T).