BA BA2 BA4 BAD Dual99v Build Thread

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ixox
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby ixox » Sun Feb 14, 2016 12:24 am

I found people who have the same digital noise problem on groupdiy, it really sounds like RF to which the jlm99v must be sensitive.
I realise my KRK monitor has exactly the same noise.

I replace RGain with a 22ohm resistor, rewire the output transfo, and use an opa2604.
It works and sounds good, i'm happy :D

Xavier

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby Joe Malone » Mon Feb 15, 2016 12:03 pm

ixox wrote:Hi Joe,

Unfortunately no good news : still the electronic/digital noise with the jlm99v.
I tried in another audio interface.. No success.
I added an output transfo... same thing.
(As i read somewhere 0v and +out from the BA to the input of the transfo...)

Reminder : The noise is only present when i use my jlm99v in my BA.
when used with an opa2604, i don't have this noise at all.
My BAD (2 * opa2604) does not have this noise neither.

I attached some pictures.
A sample of the noise sound is here :
https://www.dropbox.com/s/koeaklrt3y754ch/BA.mp3?dl=0

Let me know if you have any idea, else i'll go back with the OPA2604 and enjoy the few additional DB :wink:

Edited, additional info :
. Turning the gain pot modifies at the same time the volume of the noise.
. Modifying the inpug stage (phantom power, PAD, or unplug the mic) has NO impact.

Thanks,

Xavier


HI Xavier
Which one of our 48v SMPS power supply are you running these with?
Joe :-)
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby ixox » Mon Feb 15, 2016 6:10 pm

This one :
powerSupply.jpg
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby Joe Malone » Mon Feb 15, 2016 8:02 pm

ixox wrote:I found people who have the same digital noise problem on groupdiy, it really sounds like RF to which the jlm99v must be sensitive.
I realise my KRK monitor has exactly the same noise.

I replace RGain with a 22ohm resistor, rewire the output transfo, and use an opa2604.
It works and sounds good, i'm happy :D

Xavier


HI Xavier missed this post
The JLM99v must have a CLoad of 440pF. 220pF in CL position and 220pF in CZ position with RZ 0ohm link. Otherwise JLM99v will oscillate
Joe :-)

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby ixox » Tue Feb 16, 2016 12:05 am

Joe Malone wrote:HI Xavier missed this post
The JLM99v must have a CLoad of 440pF. 220pF in CL position and 220pF in CZ position with RZ 0ohm link. Otherwise JLM99v will oscillate


Really ? Even when wired with Fixed Impedance ?

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby Joe Malone » Tue Feb 16, 2016 10:42 am

ixox wrote:
Joe Malone wrote:HI Xavier missed this post
The JLM99v must have a CLoad of 440pF. 220pF in CL position and 220pF in CZ position with RZ 0ohm link. Otherwise JLM99v will oscillate


Really ? Even when wired with Fixed Impedance ?


Yes it can sometimes depending on the JLM99v. I listened to the mp3 file and that just sounds like digital hash due to a ground loop with a mains grounded computer system.

If you feed the transformer output to the XLR/TRS without the ground wire does that make a difference in noise level?

As long as 10R is on the BA PCB it forms a filter for the SMPS with 2 x 470uF caps which will not let in any SMPS noise if the SMPS is not overloaded or faulty. What else is the 48v SMPS running?
Joe :-)

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby ixox » Tue Feb 16, 2016 8:02 pm

Thanks for you help Joe.
I'll give it a try.

My 48v SMPS is running one BAD and one BA in the same box.

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby tphardisty » Wed Feb 17, 2016 4:58 pm

Hello, first time poster!

I am a highly amateur electronic builder (emphasis on *highly*!) and am attempting a build of the dual 99v.

I am fumbling my way through and have so far built 1 of the preamps and am hoping I haven't messed anything up and/or fried the PCB with my dodgy soldering.

I have one question at the moment, which is just to clarify whether, with the dual 99v, I need to install parts marked with a * or a #?

There are a few resistors on the preamp and a few more on the DI that I have come across so far.

Also, there is no zener diode in the kit, so I am assuming that doesn't need installation?

Thanks!

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby Joe Malone » Thu Feb 18, 2016 11:49 am

tphardisty wrote:Hello, first time poster!

I am a highly amateur electronic builder (emphasis on *highly*!) and am attempting a build of the dual 99v.

I am fumbling my way through and have so far built 1 of the preamps and am hoping I haven't messed anything up and/or fried the PCB with my dodgy soldering.

I have one question at the moment, which is just to clarify whether, with the dual 99v, I need to install parts marked with a * or a #?

There are a few resistors on the preamp and a few more on the DI that I have come across so far.

Also, there is no zener diode in the kit, so I am assuming that doesn't need installation?

Thanks!


HI BAD PCB in Dual99v kit doesn't need any of the * or # parts fitted. If you have the 10k resistors fitted it doesn't matter either way. No zeners or BD681 transistors are fitted. Zener positions are left blank and BD681 positions both has wire link between C & E as shown by white line on overlay. Also feel free to email me clear well lit large photo of the top and bottom of any of the PCBs if you want them checked over before powering up. Or ask any questions you have here while you are building :-)
Joe :-)

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby tphardisty » Sat Feb 20, 2016 3:01 pm

Thanks so much for your help, Joe. I will definitely send you those pictures when I'm ready, if that's cool!

I have a couple of new questions! Ha.

If I have the *10k resistors installed on one of the preamps, but not the other - will that cause any issues? Should I snip them off the one?

I'm also wondering if the 6k8 resistors need installation on the XLR PCB? They don't seem to be in the pack (although I haven't trawled through every single bag yet)

Lastly - how is the red LED for the 48k switch connected? I can see it in some of the pictures but not clearly enough to emulate, and I can't see it on the overlay. Apologies if it's on there and I'm just missing it!

Cheers, I really appreciate the help!

-Tom

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby Joe Malone » Sun Feb 21, 2016 10:11 pm

tphardisty wrote:Thanks so much for your help, Joe. I will definitely send you those pictures when I'm ready, if that's cool!

I have a couple of new questions! Ha.

If I have the *10k resistors installed on one of the preamps, but not the other - will that cause any issues? Should I snip them off the one?

No either way will make no difference.

I'm also wondering if the 6k8 resistors need installation on the XLR PCB? They don't seem to be in the pack (although I haven't trawled through every single bag yet)

NO only the XLR's and terminal block and IDC10 pin header.

Lastly - how is the red LED for the 48k switch connected? I can see it in some of the pictures but not clearly enough to emulate, and I can't see it on the overlay. Apologies if it's on there and I'm just missing it!

Cheers, I really appreciate the help!

-Tom


The led legs solder to the top 2 legs of the 48v switch. Long LED leg goes to the switch leg closest to the edge of the PCB. See Go between kit build thread for photos.
Joe :-)

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby tphardisty » Tue Feb 23, 2016 7:02 pm

Thanks again Joe, that's so helpful.

Okay, last question, I think - nearly ready to go!

I've attached a terrible paint drawing of my interpretation of the wiring from the terminal blocks of the 99vs. Have I understood correctly?
I am confident my wiring of the pots and the XLR IO is fine, so I have left them off. I have only really detailed the connection of the two 99vs and where they are going cause that's what is kind of confusing me. I hope it makes sense. Have I interpreted it correctly?

Again, sorry for the terrible pic. And thanks for the help.

-tom.
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby Joe Malone » Wed Feb 24, 2016 8:02 am

tphardisty wrote:Thanks again Joe, that's so helpful.

Okay, last question, I think - nearly ready to go!

I've attached a terrible paint drawing of my interpretation of the wiring from the terminal blocks of the 99vs. Have I understood correctly?
I am confident my wiring of the pots and the XLR IO is fine, so I have left them off. I have only really detailed the connection of the two 99vs and where they are going cause that's what is kind of confusing me. I hope it makes sense. Have I interpreted it correctly?

Again, sorry for the terrible pic. And thanks for the help.

-tom.


HI Tom
Yes that is correct :-)
Joe :-)

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby tphardisty » Sat Feb 27, 2016 4:02 pm

Thanks Joe!

I've got it finished and switched it on - the lefthand (when looking at the front) doesn't pass audio at all, but the one on the right works perfectly, haha!
One out of two ain't bad! The one that doesn't work was the first one I worked on and there is some dodgy soldering that I can't seem to smooth out after the fact, and some parts where I was worried I had fried the PCB - it looks a bit discoloured.

Does this sound like the sort of thing that would cause it to not pass anythign? I get nothing at all (ie. not even noise) from the XLR input and the DI input. I've tried all combinations of switches on and off and it doesn't help. The 48v LED does come on when you flip the switch. I'll try get some pics to you ASAP if that'll help. Thanks for any clues! I'm guessing it'll be a case of rebuying the BAD sans transformer and opamps...?

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Postby Joe Malone » Sun Feb 28, 2016 10:17 am

tphardisty wrote:Thanks Joe!

I've got it finished and switched it on - the lefthand (when looking at the front) doesn't pass audio at all, but the one on the right works perfectly, haha!
One out of two ain't bad! The one that doesn't work was the first one I worked on and there is some dodgy soldering that I can't seem to smooth out after the fact, and some parts where I was worried I had fried the PCB - it looks a bit discoloured.

Does this sound like the sort of thing that would cause it to not pass anythign? I get nothing at all (ie. not even noise) from the XLR input and the DI input. I've tried all combinations of switches on and off and it doesn't help. The 48v LED does come on when you flip the switch. I'll try get some pics to you ASAP if that'll help. Thanks for any clues! I'm guessing it'll be a case of rebuying the BAD sans transformer and opamps...?


Email me some clear well lit in focus photos of the faulty channel wiring etc and top and bottom of the PCB that is not working removed from the case to joe@jlmaudio.com some I can check it over for you.
Joe :-)

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