BA BA2 BA4 BAD Dual99v Build Thread

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Sylvain
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Location: QC, Canada

Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Sylvain »

Hi Joe,

You're right it's not quite a short. (I was checking with continuity setting on my meter, with a "beep")

I have 15R accross tranny primary and 30R accross XLR pins 2 and 3...

Sylvain
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Sylvain »

Hi Joe,

Can the DI or it's ribbon cable have something to do with it?
I looked at the ribbon and it seems kind of tight in there between the VTX and the back of the DI pcb...

There seamed to be a tiny tiny hole pierced in the ribbon by the slightly protruding capacitor legs at the back of the DI pcb.

That's all I can find... I don't know.... :? I am at a loss at this point.

But the BA does work (after a change of 99V). I just hpoe it keeps working.

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Joe Malone
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

Sylvain wrote:Hi Joe,

Can the DI or it's ribbon cable have something to do with it?
I looked at the ribbon and it seems kind of tight in there between the VTX and the back of the DI pcb...

There seamed to be a tiny tiny hole pierced in the ribbon by the slightly protruding capacitor legs at the back of the DI pcb.

That's all I can find... I don't know.... :? I am at a loss at this point.

But the BA does work (after a change of 99V). I just hpoe it keeps working.
Any short in the system could do something so always best to have none.
Joe :-)
JLM Audio
Capturing Audio without Injury

Sylvain
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Sylvain »

That's for sure.

Thanks again Joe.

audioboog
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by audioboog »

Hi Joe
I´ve just bought two BAD pcb:s. They look superb. I´m planning to use Yamaha-parts. GA8027 as input trafo, 80100 opamp and GA80281 as output trafo. Now to my question. Is there a possibility to get some tips for a BOM. Just to avoid problems.
Thanks in advance.
Bye Audioboog from Sweden

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Joe Malone
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

audioboog wrote:Hi Joe
I´ve just bought two BAD pcb:s. They look superb. I´m planning to use Yamaha-parts. GA8027 as input trafo, 80100 opamp and GA80281 as output trafo. Now to my question. Is there a possibility to get some tips for a BOM. Just to avoid problems.
Thanks in advance.
Bye Audioboog from Sweden
These will work fine on the BA, BAD pcb normally with no changes.

I don't recognize that input transformer number but if is is the usual 300:2.7k transformer from PM2000 (usually GA80980) Rload fixed = 27k or Rload variable = 100k log in series with 10k, RZobel = 2.7k CZobel = 470pF
Joe :-)
JLM Audio
Capturing Audio without Injury

audioboog
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by audioboog »

Hi Joe

Thanks for your answer. Sending a picture of the input trafo. I think its a smaller kind then in the PM2000.
Bye Audioboog
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Joe Malone
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

audioboog wrote:Hi Joe

Thanks for your answer. Sending a picture of the input trafo. I think its a smaller kind then in the PM2000.
Bye Audioboog
bild.JPG
What is the Yamaha module that the transformer is mounted on?

As the circuit for that module will give use the info needed for the transformer loading.
Joe :-)
JLM Audio
Capturing Audio without Injury

VersaMusic
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by VersaMusic »

Hi,

I'm having a problem with my pair of BADs. With the left BAD connected, no problems. With the right BAD connected, also no problems. With both BADs connected, *and* with a microphone plugged in, there's what sounds like a ground hum - if the mic is unplugged the hum goes away, or if I disconnect *one* of the BADs (doesn't matter which one) the hum goes away.

I've tried disconnected the DIs, moving the opamps around, checking things over to make sure nothing's shorting and everything looks fine. Does anyone have a suggestion for where this hum might be coming from, and how I might get rid of it?


Here's a high resolution PNG - I've removed the ribbons connecting the DIs for the photo. (medium resolution JPG embedded below): http://dl.dropbox.com/u/5380438/Preamps.png

Image


Thanks for your help!

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Joe Malone
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

VersaMusic wrote:Hi,

I'm having a problem with my pair of BADs. With the left BAD connected, no problems. With the right BAD connected, also no problems. With both BADs connected, *and* with a microphone plugged in, there's what sounds like a ground hum - if the mic is unplugged the hum goes away, or if I disconnect *one* of the BADs (doesn't matter which one) the hum goes away.

I've tried disconnected the DIs, moving the opamps around, checking things over to make sure nothing's shorting and everything looks fine. Does anyone have a suggestion for where this hum might be coming from, and how I might get rid of it?

Here's a high resolution PNG - I've removed the ribbons connecting the DIs for the photo. (medium resolution JPG embedded below): http://dl.dropbox.com/u/5380438/Preamps.png

Thanks for your help!
You have the input XLRs wired backwards with pin 1 and 2 swapped. Swap the red and white wires on the input XLR's and you will be working properly. Always remember in and out XLR's are mirror images of each other. There is usually a large chassis lug on the XLR back above pin 1 to help identify it.
Joe :-)
JLM Audio
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VersaMusic
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by VersaMusic »

Ah ha! Thanks so much! I'll give that a shot.

theaterguy
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by theaterguy »

Hi Joe!

Almost there, but I want be sure of some details before booting this thing (BA with JML14 + Hybrid + 315mA SMPS).

- #10k fitted and extra wire
- #BD681
- a small brown cap, reading "281". Where is this supposed to go? On a CLFixed I have "221".
- There was not a RG (68 ohm resistor) on the package, but I can get a substitute.
- one 27K resistor not found it's place.

thanks

sonicwarrior
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by sonicwarrior »

Did anyone already use the Haufe ST8456 as an input transformer? (1+1:5)
I have one with an LL1538 adapter PCB and I'm wondering if I can use it with a BA. I guess I can use the same settings as with the LL1538 in the 1:5 configuration, right?

I still need a second BA to fill a Dual Mic Pre case and I'm still not sure what configuration to choose. My first uses a JLM14 and OPA604 opamp. I'd like to use a different xformer and a DOA (as I have so many and the BAs are one of the few PCBs where the DOA pins I have fit).

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Joe Malone
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

theaterguy wrote:Hi Joe!

Almost there, but I want be sure of some details before booting this thing (BA with JML14 + Hybrid + 315mA SMPS).

- #10k fitted and extra wire
- #BD681
- a small brown cap, reading "281". Where is this supposed to go? On a CLFixed I have "221".
- There was not a RG (68 ohm resistor) on the package, but I can get a substitute.
- one 27K resistor not found it's place.

thanks
Doesn't matter if #10k is fitted or not. BD681 not needed. Jumper C to E on both BD681 positions. Only 2 values of ceramic caps in the kit 47pF and 220pF so will be the 221 as 281 is not a standard value. The second 220pF is added to C Zobel and link to R Zobel only when using variable impedance. Extra 220pF not used with fixed 10k Rload. 27k is only used with OEP input transformer.
Joe :-)
JLM Audio
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Joe Malone
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

sonicwarrior wrote:Did anyone already use the Haufe ST8456 as an input transformer? (1+1:5)
I have one with an LL1538 adapter PCB and I'm wondering if I can use it with a BA. I guess I can use the same settings as with the LL1538 in the 1:5 configuration, right?

I still need a second BA to fill a Dual Mic Pre case and I'm still not sure what configuration to choose. My first uses a JLM14 and OPA604 opamp. I'd like to use a different xformer and a DOA (as I have so many and the BAs are one of the few PCBs where the DOA pins I have fit).
Should work fine with adaptor on the BA PCB. Probably will work best like the LL1538 set to 1:2.5 with both primaries in series. (Use low ratio jumper on BA PCB). But easy to try both ways with the ratio jumpers on the BA PCB.
Joe :-)
JLM Audio
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