BOSOZ Problem

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
vdi_nenna

vdi_nenna

Member
Joined 2000
Paid Member
I have yellow connected to "A".
Black is not connected.
Red is in "D".

Are freakin' kidding me!!!

JJ, you saw the key at APEX Jr, right? I connected it based the instructions Steve sent me when I bought the transformers.

Now I have to order new rectifiers!:hot:

I'll try what Raoul suggested.

thanks.
 
R

Raoul

Member
Joined 2003
I checked the ApexJr site and looked at the wiring diagram Steve had listed. Warranting a second look, I pulled my dusty BoSoZ off the shelf and took some measurements of the transformers. The wiring diagram ApexJr lists is, not suprisingly, CORRECT. Sorry about any confusion or raised hopes. The red and yellow secondaries on my transformers measured 30.5VAC unloaded, and the black is the centertap. Sorry to throw you off track. I messed around with a few different configurations and obviously soldered the secondaries back incorrectly before I put it back on the shelf for a long winter's nap...

Sorry again. I guess the hunt continues.
 
vdi_nenna

vdi_nenna

Member
Joined 2000
Paid Member
I tried switching the secondaries and it fried the rectifiers or whatever was left of them.

I checked the secondaries w/ no load and I got 31.5 v on the red and yellow. I should have checked this first. :eek:

I'm thinking of scrapping this project for something else. I really don't trust those broads from AudioXpress. The traces and pads are weak.

I'm thinking of maybe an Aleph P or 1.7. One of then is almost the same as the BOSOZ.

Any suggestions?

Thanks,

Vince
 
J

jupiterjune

Member
Joined 2006
Vince-

I would work out the problems with the BOSOZ first before ditching them. The Aleph P 1.7 is a much more complicated version of the basic BOSOZ circuit.

You can run the main boards off of any power supply available, all you need is +V, -V, and ground. Anything from 20V to 60V should work, and it doesn't need to be regulated.

Anyway, the problem seems to be in your power supply, and you will need a power supply for any other preamp. Ditching PS boards might be worthwhile, but you still have to find another set of boards for a PS.

Like I said, I never got past the burning bridges. I can post a picture tonight of what I did.

JJ
 
vdi_nenna

vdi_nenna

Member
Joined 2000
Paid Member
Circuit's Up!

I made a small power supply just to power up the main circuit and the voltages look good. The PS is +-41.5 volts. I get 21-22 volts at the drain, -3.5 at the sources, 0 volts at the gate. Nothing smoked.

I'm going to plug it in to my system and see what I get out of it.

I'm still not sure what was wrong with regulators.

thanks for your advice,

Vince
:D
 
J

jupiterjune

Member
Joined 2006
JJ
Mostly it reminds me of 'Good Times'

I wasn't all that happy with the imaging I got with the stock BOSOZ. So I put 100K resistors from the output of capacitors to the gates of the input fets.

It made a big difference (to my ears), but if you are happy with the BOSOZ, then there is no need.

My gear runs really quiet with the BOSOZ as well.

JJ
 
vdi_nenna

vdi_nenna

Member
Joined 2000
Paid Member
Listened to it again tonight and it sounded even better than yesterday. I'm really blown away. The image is big! It's a whole other level of sound. It's running unbalanced too. :cool:

I wonder how much better the X'ed version sounds, or the CCSXBOSOZ or a JFET... :rolleyes: I'll live with this for a while. I want to finish the Mini XA now. I have a 6' heat sink I'm dying to chop up!!

Now using a 4 deck, 10k stepped attenuator and it makes a huge difference in the imaging. With the BOZ, the image with a resistive wafer pot drifted all over the place. The step attenu. was a pain to build, but now I see why they are so coveted.

Do you think the regulator helps or hinders the sound? Do you think it makes the image more stable or focused?

V~
 
vdi_nenna

vdi_nenna

Member
Joined 2000
Paid Member
have you excellent non-reg variant?
Click to expand...

No, it is not excellent in the least. The only thing good
about it is that it can produce over 2.5 amps of current. Other
than this capability, it is the simplest of power supplies.

After building 2 regulated supplies and neither functioned for me, I'm reluctant to build another one. :bawling:
I emailed passdiy.com. Desmond recommended rebuilding, but I don't know.

I made a 2 chassis setup, so there's room for both types of PS.
It would be cool to test both. We'll see, but for now I'm happy.

V~
 
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
vdi_nenna said:


No, it is not excellent in the least. The only thing good
about it is that it can produce over 2.5 amps of current. Other
than this capability, it is the simplest of power supplies.

After building 2 regulated supplies and neither functioned for me, I'm reluctant to build another one. :bawling:
I emailed passdiy.com. Desmond recommended rebuilding, but I don't know.

I made a 2 chassis setup, so there's room for both types of PS.
It would be cool to test both. We'll see, but for now I'm happy.

V~
Click to expand...


if you stay with unreg variant,just toss in every cap you have in house

:clown:

edit:

later- when you learn thing or two , you can always put reg in box
 
R

Raoul

Member
Joined 2003
BOSOZ PS

Hi Vince,

I have a single built, but untested, BOSOZ power supply board kicking around in a parts box somewhere. I had planned on making a dual supply pre, but ended up just using one board in a stereo configuration. I can try to dig it out this weekend if you want to give it a whirl.
 
R

Raoul

Member
Joined 2003
Sorry I didn't get to you sonner. I almost forgot that I had that board. I will set it aside next time I am digging around in the garage in case you may need it. The audioXpress boards experience trace fatigue very quickly, as I am sure you have noticed. I used lead free solder when I first built the boards, and had a helluva time swapping components.
 
vdi_nenna

vdi_nenna

Member
Joined 2000
Paid Member
R~

The parts should arrive today. The traces are not good. They are like gold leave, but without the gold.

I have a solder sucker, and I hope it can clear most of the solder without tearing up the pads on the board.

I'll let you guys know what happens.

V~

P.S.
If for some strange reason I have some sort of mental blockage when I come to building regulators, can you hold on to that reg board? If this rebuild fails, make me an offer for it?

Thx,

v~
 
R

Raoul

Member
Joined 2003
Yeah, I know. The audioXpress boards are pretty ridiculous. The traces actually seem to lift a bit and allow solder to flow underneath the traces. I used Pb free solder, and as a consequence I had to add a bit more heat. It was pretty unnerving to see the traces develop a crinkled look in the immediate vacinity of the pad, but all the connections seem solid and tight. Maybe audioXpress intended it that way. You actually solder both sides of the pad to the component lead, doubling the contact area. :rolleyes:

The experience turned me off to both Pb free solder and audioXpress boards. It seems like you only get one solid shot at the thing. Anything beyond that and you are taking your chances. To complicate matters, it is extremely difficult to solder with your fingers crossed. That said, I have managed to swap parts on the main board successfully, it just took a lot of care.

Anyway, I found the spare board, so if you need it just let me know.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom