Dual99v Rack kit build thread 2024

[Joe Malone]

Dual99v is built on the BAD PCB which is designed for easy mounting by it 3 front edge toggle switches like the GO between and GO between plus kits share and are powered direct from one 48v rail supplied usually by our external 48v built MEPS Green SMPS which can run on any mains voltage in the world with out switching. This 48v supplies phantom power and +/-24v for the opamps to run on so makes building many types of transformer input single and dual opamp types of mic pre much easier to build.

Notes and Errata
FIt BD681 at back of the BAD pcb (black plastic side closest to pcb edge)
Fit 100uF 50v to C16 instead of 470uF 50v cap to help new power supply start the Dual99v easier.

BAD PCB


Complete circuit of JLM Baby Animal Dual PCB here

The BAD PCB is easy to assemble with all parts with there value marked on the PCB needing to be fitted. Parts marked with * or # and zener diodes are only needed if running on higher than 48v or running opamps that need less then the +/-24v to run on. Parts with a name like Rload, CLoad, Rzobel, CZobel, RPad, RGain need to be selected to match the input transformer and opamp used. Their values for projects like the Dual99v can be found on the overlay sheet for the project.

NEW Dual99v, BAD Overlay wiring Larger copy here

Dual99v 240818.png

OLD Dual99v, BAD Overlay wiring PDF Larger PDF copy here


Some helpful photo's (If there is some detail you need a photo off let me know and I will add it here)

BAD PCB fully assembled except for 2 x 270R for RGain, input transformer and opamps Larger photo here
Notes & Errata#BD681 jumper is wrong in the photo below. Should be E-C. Also Dual99v does not use a Cload cap any more. So leave blank.


BAD PCB fully assembled as Dual99v (Note 2 links needed between centre pin and E on each BD681 position and 1mm gap under transformer)
Notes & Errata#BD681 jumper is wrong in the photo below. Should be E-C. Also Dual99v does not use a Cload cap any more. So leave blank.


Sit toggle hard against the PCB and solder one front support leg on each toggle to hold in place.


Check toggles level and square to each other and solder all legs and support pins


Dis-guard flat washer and fit the rear nut (should be a few mm gapped from the end of the thread) and washer to all three toggles


Nuts should just screw on an tighten with minimum thread sticking out if the rear nut is set correctly


Nuts and washer order for Power switch


Same again space the rear nut up so the minimum of thread sticks out past front nut.


DC connector and Fuse wiring


All Pot wiring for BAD Dual99v PCB


Gain pot wiring (Photo shows BAD/Dual99v dual pot)
Note BA is the same but only a single pot


Output Pot wiring


Z pot wiring
OEP/VTX = 10k in series with 100k log pot. (As shown in photo below for Dual99v)
JLM14 = 2k2 in series with 50k log pot (2k2 resistor solders to both pins on the left and red wire solders to all 4 pins on the right)


Output transformer to IOXLR PCB (Note link wire between -2 and +3 is hidden in this photo)


Full Dual99v internal wiring Larger photo here

[seeker]

Hi, I am firing up my Dual 99v rack kit for the first time and I'm getting blinking power light, and when checking power coming in its pulsating in between roughly 15v and 30v. Clearly I must have missed something on the assembly... can you give me a suggestion of what to check?

Thanks,

Jason

[Joe Malone]

Hi, I am firing up my Dual 99v rack kit for the first time and I'm getting blinking power light, and when checking power coming in its pulsating in between roughly 15v and 30v. Clearly I must have missed something on the assembly... can you give me a suggestion of what to check?

Thanks,

Jason

HI Jason
This is the SMPS power supply going into hiccup mode protection mode. Modern green high efficiently SMPS go into this mode almost too easily. Especially if charging some large capacitors when powering up. Did you happen to do the Notes and Errata changes at the top of this thread? C16 should be 100uF and BD681 at back fitted to give soft start.

Also always best to power one channel at a time in case there are any problems or shorts with one channel. Just removing the +48v from the BAD pcb one one side is all that is needed.

If stuck send me some clear large in focus photos of the top and bottom of the PCBs to check for you.

[seeker]

Thank you for the quick reply! I did not fit the 100uf or bd681. Does this mean I should also fit R21 as well?


Thank you,

Jason

[Joe Malone]

Thank you for the quick reply! I did not fit the 100uf or bd681. Does this mean I should also fit R21 as well?


Thank you,

Jason

Yes correct R21 10k is needed

[seeker]

Hey Joe, so I installed c16 = 100uf and bd681and R21 = 10k. When the two channels are both hooked to 48v, I get the same pulsing power light, and you can hear the relays flicking on and off. So I detached the 48v from one channel at a time and no pulsing lights... Then I checked each channel individually with a dynamic mic and a guitar through the DI. Both channels seem to be perfect on their own...


Thanks!

Jason

[Joe Malone]

Hey Joe, so I installed c16 = 100uf and bd681and R21 = 10k. When the two channels are both hooked to 48v, I get the same pulsing power light, and you can hear the relays flicking on and off. So I detached the 48v from one channel at a time and no pulsing lights... Then I checked each channel individually with a dynamic mic and a guitar through the DI. Both channels seem to be perfect on their own...


Thanks!

Jason

If you unplug 1 or 2 of the FETDI 10-pin plugs does the 2 preamps power up ok?

[seeker]

So if I unplug Channel A DI, I get two pulses from the power supply then it seems to be fine (though I did not listen to output) however if I instead unplug channel B DI and leave A plugged in i get the same pulsing as before.

Unplugging both DIs the power light seems to pulse once or so and then stay steady.


Thanks,

Jason

[Joe Malone]

So if I unplug Channel A DI, I get two pulses from the power supply then it seems to be fine (though I did not listen to output) however if I instead unplug channel B DI and leave A plugged in i get the same pulsing as before.

Unplugging both DIs the power light seems to pulse once or so and then stay steady.


Thanks,

Jason

Sorry I was away for the day. Testing just now with this new batch of 25w smps on 115vac it seems we have to go back to the original soft start mod.

Cut track and add wire as shown and mic pre should power up. Let me know how this goes.

[seeker]

Thanks for the help Joe, both channels now power up and sound great! Ive only played with it for a few min but I'm very impressed.

I've occasionally gone down the rabbit hole of power supplies, If I was to power this from a linear PSU at some point in the future, should I remove the soft start mod, or would that be ok to leave it?

Thanks,

Jason

[seeker]

Here’s a few pics… the lighting is bad, but I’m pretty happy with the build….

And I’m very thankful for your quick replies!


If you need a beta builder in the US, let me know!

[seeker]

Hi Joe, I was using my Dual 99v with an sm7B which eats gain... and opened it up fully.... i noticed that when completely turned up the preamp clicked into a weird thin, kind of harsh sound... one notch down sounds fine. Is this normal? did I miss something in my build?


Thanks a lot,

Jason

[seeker]

Hi Joe, I know its been a while since I completed this build, but life got in the way of me getting much use out of these, and recently I did some tests based on things I was hearing. It seems the gain on my build is low, and seems light in the bass, I compared these to the TG preamp BC both have 75 db gain, and the TG is definitely louder and fuller in the bass. I've been over the build and I cant find any errors, but I must have done something wrong. Some help would be very much appreciated! Also, the only odd thing i can say is that when the gain is opened fully there is a change in timbre.

Thanks.


Jason

[Joe Malone]

Hi Joe, I know its been a while since I completed this build, but life got in the way of me getting much use out of these, and recently I did some tests based on things I was hearing. It seems the gain on my build is low, and seems light in the bass, I compared these to the TG preamp BC both have 75 db gain, and the TG is definitely louder and fuller in the bass. I've been over the build and I cant find any errors, but I must have done something wrong. Some help would be very much appreciated! Also, the only odd thing i can say is that when the gain is opened fully there is a change in timbre.

Thanks.


Jason

If you can do a loop test with free RMAA rightmark or Plugin doctor and send me the sav file for RMAA or image for plugin doctor and can check if it looks to be working correctly or not. Set minimum CCW gain and pad on and level on fully CW.

Any change at full gain will be oscillation so make sure the ribbon wire is twisted tightly and in and out wires and Z pot wires spaced apart from each other.