Question: I'm trying out adjustments to P3. I noticed that adjusting P3 has brough up my bias 10% Should I adjust P1 and P2 down to bring down the bias or will it be OK while I experiment?
Question: I'm trying out adjustments to P3. I noticed that adjusting P3 has brough up my bias 10% Should I adjust P1 and P2 down to bring down the bias or will it be OK while I experiment?
I haven't touched P3 yet. I noticed that BIAS is quite tricky to adjust - every time I lift up the cover temperature is going down and BIAS is going down. I probably should have used a bit bigger heatsinks...
A bit confused here. You say you are going unbalanced to balanced input and I see a 4 deck attenuator but I only see one BA3 FE board.? Nice and neat build.
nash
Question: I'm trying out adjustments to P3. I noticed that adjusting P3 has brough up my bias 10% Should I adjust P1 and P2 down to bring down the bias or will it be OK while I experiment?
If the Bias has moved then quite probably the offset has also shifted.
Re-set bias and offset for safety.
Thats the funny thing, changing P3 does Not change the offset. It stays fine until I try to adjust P1 or P2 to bring down the bias...then all goes wonky.
I ran it for an hour last night with elevated bias (10%). It seems OK. I'm going back to my original settings tonight for a taste test because a very good friend of mine has sold me on the idea that all tests should be A-B-A.
As it stands, I have to say the difference is pretty small having gone from center position on P3 to one half way to full "forward". I thought I'd hear a big shift...
Amazing
Just wanted to show my new BA-3😀
Thanks to 6L6 for all his help.
Have played on it a couple of days with my Aleph J, just wonderful🙂
Merry Xmas to all from Thomas, Denmark
Just wanted to show my new BA-3😀
Thanks to 6L6 for all his help.
Have played on it a couple of days with my Aleph J, just wonderful🙂
Merry Xmas to all from Thomas, Denmark
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Hi Thomas,
we are a few affectionados here en Denmark, dont know if I spelled it correctly.
But I am using a BA3 and a F5 also, in Horsens.
Best regards
Arthur.
we are a few affectionados here en Denmark, dont know if I spelled it correctly.
But I am using a BA3 and a F5 also, in Horsens.
Best regards
Arthur.
Congratulations and beautiful casework!
I'm going to use that same power switch on my F-6 power amp and BA-3 preamp.
Where did you source your input selector? I like it!
I'm going to use that same power switch on my F-6 power amp and BA-3 preamp.
Where did you source your input selector? I like it!
Just wanted to show my new BA-3😀
Thanks to 6L6 for all his help.
Have played on it a couple of days with my Aleph J, just wonderful🙂
Merry Xmas to all from Thomas, Denmark
Last edited:
Just wanted to show my new BA-3😀
Thanks to 6L6 for all his help.
.......
Have played on it a couple of days with my Aleph J, just wonderful🙂
Merry Xmas to all from Thomas, Denmark
Do not wire anything to toroid central bolt !!
that's most probably short circuit , you have there
Oversized images corrected. Please see this thread:http://www.diyaudio.com/forums/everything-else/183084-pictures-why-not-attach-them.html
After successfully building F6 amp I decided to build a BA-3 preamp to go along with it.
However on powering up to bias one fully built channel of the board (no output cap yet as I wanted make sure board biased up correctly before soldered 10 uf cap as it takes all the real estate) using variac, I am running into trouble.
I am measuring about 8 v at full voltage across both R 11 and R 10 with no effect of P1 and P2 pots whatsoever. I had to lower voltage as R11 and R10 became brown but still measure 22 r.
I am using fairchild parts from mouser Fqp3N30 at Q3 and Fqp3p20 at Q4.
P1 and P2 are 2k pots and I made sure they are zeroed out before powering with a variac.
Jfets tightly matched Sk170 idss 7.1 and SJ74 Idss 7.09
V+ at 24 v, V- at negative 24 v Ground at G on PCB.
What I am doing wrong? Double checked the value of all resistors. All check out fine. Picture attached.
Please help.
However on powering up to bias one fully built channel of the board (no output cap yet as I wanted make sure board biased up correctly before soldered 10 uf cap as it takes all the real estate) using variac, I am running into trouble.
I am measuring about 8 v at full voltage across both R 11 and R 10 with no effect of P1 and P2 pots whatsoever. I had to lower voltage as R11 and R10 became brown but still measure 22 r.
I am using fairchild parts from mouser Fqp3N30 at Q3 and Fqp3p20 at Q4.
P1 and P2 are 2k pots and I made sure they are zeroed out before powering with a variac.
Jfets tightly matched Sk170 idss 7.1 and SJ74 Idss 7.09
V+ at 24 v, V- at negative 24 v Ground at G on PCB.
What I am doing wrong? Double checked the value of all resistors. All check out fine. Picture attached.
Please help.
