BA BA2 BA4 BAD Dual99v Build Thread

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

MichaelGNunn wrote:
Sat Apr 17, 2021 5:03 am
Post Mon Apr 12, 2021 1:18 am

MichaelGNunn wrote: ↑
Hi Joe, I got everything together on my dual 99V and it sounds great aside from some noise issues! I looked through the forum, and it seems someone else has had this issue. It sounds like some electrical interference or grounding issue. can this be fixed by getting a power conditioner that separates my analog equipment from digital equipment computer, or do I need to open it up?

Thanks,
MN
HI Michael
Do you have a sample of the noise you can send me with nothing connected to the input of the mic pre?


Hey Joe,

I posted a broken link. This one should work! This is with all three knobs turned all the way right

https://soundcloud.app.goo.gl/nN99k1SjcBRZNMuW7
HI Michael
What A/D are you running this into ? Is it setup for pro level +18dBu to +24dBu clip level?
Joe :-)
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MichaelGNunn
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by MichaelGNunn »

Joe Malone wrote:
Mon Apr 19, 2021 9:21 am
MichaelGNunn wrote:
Sat Apr 17, 2021 5:03 am
Post Mon Apr 12, 2021 1:18 am

MichaelGNunn wrote: ↑
Hi Joe, I got everything together on my dual 99V and it sounds great aside from some noise issues! I looked through the forum, and it seems someone else has had this issue. It sounds like some electrical interference or grounding issue. can this be fixed by getting a power conditioner that separates my analog equipment from digital equipment computer, or do I need to open it up?

Thanks,
MN
HI Michael
Do you have a sample of the noise you can send me with nothing connected to the input of the mic pre?


Hey Joe,

I posted a broken link. This one should work! This is with all three knobs turned all the way right

https://soundcloud.app.goo.gl/nN99k1SjcBRZNMuW7
HI Michael
What A/D are you running this into ? Is it setup for pro level +18dBu to +24dBu clip level?
I’m running an apollo x8p, It was on +20 dBu, I can change it to +24 dBu

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

Ok +20dBu is perfect. Is the noise the exactly the same in both channels?

Does the noise stop instantly when the power switch is turned off?

Can you email me internal photos and power supply photo so I can check the build over.
Joe :-)
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mhelin59
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by mhelin59 »

Is it OK to have another op amp soldered under the DOA if the IC1/A (pins 1,2 and 3) are lifted and connected appropriately when using the BA (basic) PCB? That way you could for an example drive a balanced transformer like LL1539 (though without mixed feedback). Obviously with the output caps as the output has "some" DC (the LL1539 datasheet shows DC connected circuit meant for dual supplies).

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

mhelin59 wrote:
Thu Jun 17, 2021 6:11 am
Is it OK to have another op amp soldered under the DOA if the IC1/A (pins 1,2 and 3) are lifted and connected appropriately when using the BA (basic) PCB? That way you could for an example drive a balanced transformer like LL1539 (though without mixed feedback). Obviously with the output caps as the output has "some" DC (the LL1539 datasheet shows DC connected circuit meant for dual supplies).
It could be done but the drive between discrete and the dip8 half running inverted wouldn't be even so there is no benefit.

I would just run both primaries in parallel from the +out and return to 0v as with discrete opamp this will be easy to drive and give max headroom
Joe :-)
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mhelin59
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by mhelin59 »

Joe Malone wrote:
Thu Jun 17, 2021 11:58 am
It could be done but the drive between discrete and the dip8 half running inverted wouldn't be even so there is no benefit.

I would just run both primaries in parallel from the +out and return to 0v as with discrete opamp this will be easy to drive and give max headroom
Ok, that's also what I was afraid of, that the two outputs wouldn't be symmetric enough, will use just the DOA output, thanks.

Sam
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Sam »

Hi I've just finished one half of my BA2 2 CH Rack Kit

I'm just doing some testing and all seems well except when I wind up the gain, I'm getting a fair amount of power supply noise, more when the phantom power is engaged. I'm just not sure if I've missed something or my lead dressing is just bad. I've attached a photo.

Thanks

Sam
20210827_141106.jpg
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

Sam wrote:
Fri Aug 27, 2021 3:25 pm
Hi I've just finished one half of my BA2 2 CH Rack Kit

I'm just doing some testing and all seems well except when I wind up the gain, I'm getting a fair amount of power supply noise, more when the phantom power is engaged. I'm just not sure if I've missed something or my lead dressing is just bad. I've attached a photo.

Thanks

Sam

20210827_141106.jpg
HI Sam

The new black pcbs are supposed to be fully built and should have BD681 and trimpot fitted. We adjust the trimpot so you have about 44v at +v of the opamp as this forms a linear smoothing regulator for each mic pre which I think is the main problem here.

Build looks very neat but you need to keep your gain and impedance wiring as short a possible so I would shorten them down so they only have a bit of slack especially the impedance wiring. Also twist the ribbon cable so it forms a tight tube between the IDC headers.
Joe :-)
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Sam
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Sam »

Joe Malone wrote:
Fri Aug 27, 2021 3:47 pm
Sam wrote:
Fri Aug 27, 2021 3:25 pm
Hi I've just finished one half of my BA2 2 CH Rack Kit

I'm just doing some testing and all seems well except when I wind up the gain, I'm getting a fair amount of power supply noise, more when the phantom power is engaged. I'm just not sure if I've missed something or my lead dressing is just bad. I've attached a photo.

Thanks

Sam

20210827_141106.jpg
HI Sam

The new black pcbs are supposed to be fully built and should have BD681 and trimpot fitted. We adjust the trimpot so you have about 44v at +v of the opamp as this forms a linear smoothing regulator for each mic pre which I think is the main problem here.

Build looks very neat but you need to keep your gain and impedance wiring as short a possible so I would shorten them down so they only have a bit of slack especially the impedance wiring. Also twist the ribbon cable so it forms a tight tube between the IDC headers.

Hey Joe, thanks for the quick response. Right, I took the wrong approach when referencing the tables at the start of the thread.

Will fit them and make the adjustments and report back.

Thanks!

Sam
Posts: 4
Joined: Fri Aug 27, 2021 2:17 pm

Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Sam »

Sam wrote:
Fri Aug 27, 2021 4:06 pm
Joe Malone wrote:
Fri Aug 27, 2021 3:47 pm
Sam wrote:
Fri Aug 27, 2021 3:25 pm
Hi I've just finished one half of my BA2 2 CH Rack Kit

I'm just doing some testing and all seems well except when I wind up the gain, I'm getting a fair amount of power supply noise, more when the phantom power is engaged. I'm just not sure if I've missed something or my lead dressing is just bad. I've attached a photo.

Thanks

Sam

20210827_141106.jpg
HI Sam

The new black pcbs are supposed to be fully built and should have BD681 and trimpot fitted. We adjust the trimpot so you have about 44v at +v of the opamp as this forms a linear smoothing regulator for each mic pre which I think is the main problem here.

Build looks very neat but you need to keep your gain and impedance wiring as short a possible so I would shorten them down so they only have a bit of slack especially the impedance wiring. Also twist the ribbon cable so it forms a tight tube between the IDC headers.

Hey Joe, thanks for the quick response. Right, I took the wrong approach when referencing the tables at the start of the thread.

Will fit them and make the adjustments and report back.

Thanks!
Fitted and adjustments made. It has made a huge improvement. There's still a little power supply noise when the gain is wound up past 3 o'clock but I'm probably not being too fair to it considering I'm just running to a line in on a basic amp while testing.
20210827_170118.jpg
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

Sam wrote:
Fri Aug 27, 2021 5:03 pm
Sam wrote:
Fri Aug 27, 2021 4:06 pm
Joe Malone wrote:
Fri Aug 27, 2021 3:47 pm


HI Sam

The new black pcbs are supposed to be fully built and should have BD681 and trimpot fitted. We adjust the trimpot so you have about 44v at +v of the opamp as this forms a linear smoothing regulator for each mic pre which I think is the main problem here.

Build looks very neat but you need to keep your gain and impedance wiring as short a possible so I would shorten them down so they only have a bit of slack especially the impedance wiring. Also twist the ribbon cable so it forms a tight tube between the IDC headers.

Hey Joe, thanks for the quick response. Right, I took the wrong approach when referencing the tables at the start of the thread.

Will fit them and make the adjustments and report back.

Thanks!
Fitted and adjustments made. It has made a huge improvement. There's still a little power supply noise when the gain is wound up past 3 o'clock but I'm probably not being too fair to it considering I'm just running to a line in on a basic amp while testing.

20210827_170118.jpg
Remember with nothing plugged into the input transformer it will pick up noise. So the best test is with nothing plugged into the input and pad on. Do the second channel and see how they both work with a mic input.
Joe :-)
JLM Audio
Capturing Audio without Injury

Sam
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Joined: Fri Aug 27, 2021 2:17 pm

Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Sam »

Joe Malone wrote:
Sat Aug 28, 2021 2:55 pm
Sam wrote:
Fri Aug 27, 2021 5:03 pm
Sam wrote:
Fri Aug 27, 2021 4:06 pm



Hey Joe, thanks for the quick response. Right, I took the wrong approach when referencing the tables at the start of the thread.

Will fit them and make the adjustments and report back.

Thanks!
Fitted and adjustments made. It has made a huge improvement. There's still a little power supply noise when the gain is wound up past 3 o'clock but I'm probably not being too fair to it considering I'm just running to a line in on a basic amp while testing.

20210827_170118.jpg
Remember with nothing plugged into the input transformer it will pick up noise. So the best test is with nothing plugged into the input and pad on. Do the second channel and see how they both work with a mic input.
Hey Joe, I had a chance to get back to it today, I finished off the other side, tested and compared. It has a pretty low noise floor, the power supply noise seems to not be an issue so long as the unit is always on and since it's connected via my patchbay, it stays quiet. So I'd say I probably built it OK

I gave it a quick run with some mics and ran a couple tests, the channels seem to be matched well enough for stereo recording straight up and playing bass DI and adjusting the impedance sounds great.

Now that I've got it in my rack, I'll start tracking through it tomorrow. Just out of curiosity, would it be possible to fit an output trim to the BA2? it would be nice to really drive that input transformer! - I could always pad it after the output if I needed to though.

Great kit - simple to build and sounds great! great bang for the buck! Thanks!

Sam

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

Sam wrote:
Sun Aug 29, 2021 8:27 pm
Joe Malone wrote:
Sat Aug 28, 2021 2:55 pm
Sam wrote:
Fri Aug 27, 2021 5:03 pm


Fitted and adjustments made. It has made a huge improvement. There's still a little power supply noise when the gain is wound up past 3 o'clock but I'm probably not being too fair to it considering I'm just running to a line in on a basic amp while testing.

20210827_170118.jpg
Remember with nothing plugged into the input transformer it will pick up noise. So the best test is with nothing plugged into the input and pad on. Do the second channel and see how they both work with a mic input.
Hey Joe, I had a chance to get back to it today, I finished off the other side, tested and compared. It has a pretty low noise floor, the power supply noise seems to not be an issue so long as the unit is always on and since it's connected via my patchbay, it stays quiet. So I'd say I probably built it OK

I gave it a quick run with some mics and ran a couple tests, the channels seem to be matched well enough for stereo recording straight up and playing bass DI and adjusting the impedance sounds great.

Now that I've got it in my rack, I'll start tracking through it tomorrow. Just out of curiosity, would it be possible to fit an output trim to the BA2? it would be nice to really drive that input transformer! - I could always pad it after the output if I needed to though.

Great kit - simple to build and sounds great! great bang for the buck! Thanks!

Sam
Cool great to hear :-)

Adding an output pad only allows you to overdrive the output transformer if you have them fitted which is not as nice as just driving the input without the pad on.
Joe :-)
JLM Audio
Capturing Audio without Injury

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