I have regretted selling my BA-803 ever since. I never really knew just HOW good that amp was until it was gone! I talked to john and he told me the BA series was a single ended amp with sliding bias and heavy class A. He still rebuilds them and will not give out schematics. which is a bummer.
Zc
Zc
Thanks all for your submissions. I'll have to finely tune my sense on some of those key points. Maybe I'm missing something. I've decided to tackle it tomorrow.
I have this 100/100 MEG in my possession, and also a Bedini 10/10 which I'm considering selling. So ahem, let me know if any of you are interested in that piece.
Any further help will also be greatly accepted and appreciated.
I have this 100/100 MEG in my possession, and also a Bedini 10/10 which I'm considering selling. So ahem, let me know if any of you are interested in that piece.
Any further help will also be greatly accepted and appreciated.
bit of an update
Well I know I keep bumping this thread, but I'm pretty sure my problem no longer lies with the bias. I did a break down of it today. Heres a laundry list of what I did manage to do on this monster.
-Checked all semi-conductors
-Checked all caps
-Swapped power supply from the other channel to see if that would clear up the hum. Offset is reading at 147mv. Still a slight hum coming out of that channel. Unit appears to power.
I did want to go back maybe tomorrow and check the zoner diodes, as I was getting a bit of a low reading on one of them.
Anything else I should check or look for?
I went ahead and touched up the jack grounds too, as that thing was hanging by a thread. The original solders on these units scare me.
Well I know I keep bumping this thread, but I'm pretty sure my problem no longer lies with the bias. I did a break down of it today. Heres a laundry list of what I did manage to do on this monster.
-Checked all semi-conductors
-Checked all caps
-Swapped power supply from the other channel to see if that would clear up the hum. Offset is reading at 147mv. Still a slight hum coming out of that channel. Unit appears to power.
I did want to go back maybe tomorrow and check the zoner diodes, as I was getting a bit of a low reading on one of them.
Anything else I should check or look for?
I went ahead and touched up the jack grounds too, as that thing was hanging by a thread. The original solders on these units scare me.
does it amplify properly - do you have a 'scope?
Is the ~0.6vdc between base and emitter present on all devices?
You say "checked" how did you check??
Is this a dual mono unit? You say you swapped power supplies??
How about a jpeg of the unit and the innards?
What happens when you short the input?
_-_-bear
PS. if ur careful not to slip and short things out, you can compare voltages at the same points between the two channels.
Is the ~0.6vdc between base and emitter present on all devices?
You say "checked" how did you check??
Is this a dual mono unit? You say you swapped power supplies??
How about a jpeg of the unit and the innards?
What happens when you short the input?
_-_-bear
PS. if ur careful not to slip and short things out, you can compare voltages at the same points between the two channels.
An externally hosted image should be here but it was not working when we last tested it.
There's a picture of this beast.
I believe it would be a dual mono.
I checked all the Zeners, and had one reading 28v. I replaced it with a corrective 30v one. The offset then went from 142mv to 180mv. What?!
Still has that slight hum too.
I've also measured the ripple on the main caps. It's definitely a bit higher on the defective channel than the other.
Last edited:
the only thing I really am unsure of is the power boards on this unit. There's so many damn connectors on it, that I'm not too excited to start pulling those off, just to check a longshot.
I may have to do it however. Just wish I had the schematics to do a full sweep of that board without being blind.
I may have to do it however. Just wish I had the schematics to do a full sweep of that board without being blind.
Bedini BA-803
Now I understand why this amp weighs in a 68 lbs.
I'm in the progress of acquiring a BA-803.
How good are these amps compared to let's say Krell. Threshold, Rowland & Levinson?
I already understand it can drive my Acoustats probably.
Never saw a review in TAS or Stereophile or any German periodical.
Do John or Gary Bedini supply any schematics like Nelson Pass with Threshold amps does?
Now I understand why this amp weighs in a 68 lbs.
I'm in the progress of acquiring a BA-803.
How good are these amps compared to let's say Krell. Threshold, Rowland & Levinson?
I already understand it can drive my Acoustats probably.
Never saw a review in TAS or Stereophile or any German periodical.
Do John or Gary Bedini supply any schematics like Nelson Pass with Threshold amps does?
Attachments
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.