BA BA2 BA4 BAD Dual99v Build Thread

[papiblu]

More photos

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Cheers!

[Joe Malone]

Dear Joe,
cause Im a lazy bastard , I leave this unfinished Baby Animal in my garage for a couple of years.

It doesnt sound and I have no clue why.

Im sending you some photos, and maybe you find the problem

IM feeding it with the 48v of one of my powerplants that works perfect with other Pres.

Please let me know if you need some more photos
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Thanks in advance.

All the best

p.

With link over BD681, the trimpot shouldn't be fitted. The standard setup on black pcb is trimpot and BD681 for extra smooth reg but since you are using 48v from power plant it will be smooth. Remove trimpot.

Output transformer should be wired to +out and 0v not -out so that may stop any sound from getting out. So move wire from -out to 0v.

If still no sound check voltages at opamp sockets to 0v with no opamp fitted and with opamp fitted and let me know the voltages you get.

[MichaelGNunn]

Hey Joe,

I am putting together a Dual99v, and have a quick question on the transformers. The transformers in the pictures seem to be wired differently than the overlay, I assume I follow the overlay. In other words, should I connect the number on the transformers to the corresponding point on each pcb?

thanks,
MN

[Joe Malone]

Hey Joe,

I am putting together a Dual99v, and have a quick question on the transformers. The transformers in the pictures seem to be wired differently than the overlay, I assume I follow the overlay. In other words, should I connect the number on the transformers to the corresponding point on each pcb?

thanks,
MN

Yes the output transformers has 3 identical winding so can be wired in several correct ways.

Best to always follow the overlay and make sure you fit the wire link to the transformer which several people miss.

[MichaelGNunn]

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

[Joe Malone]

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?

[MichaelGNunn]

Joe,

Sorry for the delay, here’s a link to a sound sample:

https://soundcloud.app.goo.gl/Qtga4fhyBNJzr2ah7

[MichaelGNunn]

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

[Joe Malone]

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?

[MichaelGNunn]

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

[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.

[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).

[Joe Malone]

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

[mhelin59]

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]

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

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