BA BA2 BA4 BAD Dual99v Build Thread

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Joe Malone
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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.

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