BA BA2 BA4 BAD Dual99v Build Thread

[kolchek]

An ignorant question: I’m guessing that if i wanted to pad more than 20db the solution isn’t just increasing the value of rpad? Thanks.

[Joe Malone]

An ignorant question: I’m guessing that if i wanted to pad more than 20db the solution isn’t just increasing the value of rpad? Thanks.

If you want to pad more dB make RPad value smaller. Like in Dual99v on BAD PCB we use RPad = 51R to make 26dB pad.

[kolchek]

An ignorant question: I’m guessing that if i wanted to pad more than 20db the solution isn’t just increasing the value of rpad? Thanks.

If you want to pad more dB make RPad value smaller. Like in Dual99v on BAD PCB we use RPad = 51R to make 26dB pad.

Great. Thanks Joe.

[pkuchar]

Hi folks, got a question about the 111dc circuit boards, do any of the resisters need to be fitted? I built a BA4 with jlm 14 inputs 99v opamps and 111dc output transformers. with the 48v 25 watt power supply. They are all working but I'm getting a pulsing from the power supply. The leds get dimmer then brighter and I get an audible click. Should I upgrade the power supply to the 40 watt version?
thanks,
Peter Kuchar

[Joe Malone]

Hi folks, got a question about the 111dc circuit boards, do any of the resisters need to be fitted? I built a BA4 with jlm 14 inputs 99v opamps and 111dc output transformers. with the 48v 25 watt power supply. They are all working but I'm getting a pulsing from the power supply. The leds get dimmer then brighter and I get an audible click. Should I upgrade the power supply to the 40 watt version?
thanks,
Peter Kuchar

HI Peter
No resistors need to be fitted to the 111dc pcbs. Only 10 pin header, terminals, transformer, and XLRs

The 25w with modern black BA pcbs should boot up fine and run with a better noise floor than a 40w as long as the BD681 soft start transistor was fitted to each pcb. The hiccup mode is the protection mode for the power supply.

A good idea is to test each BA pcb one at a time on power by removing the 48v wire from the other 3 pcbs. Just to be sure they all power and work fine. Then power a second and then a third and four pcb.

Feel free to put up or email some photos for me to check over

[pkuchar]

I did fit transistors, trim pot and wired the transformer correct. I'll try to power them one at a time like you suggest.
thanks,
Peter

[pkuchar]

My voltage was running a bit high. 47.5 volts in and 24.75 out or so on all 4 pres', So I dialed the volts back to about 46.5 in and around 24.33 out and that was enough to get the power supply out of hiccup mode. now all 4 preamps are running smoothly and sounding great! I was going to use them on my 4 toms, now the highs are so smooth they sound great on overheads and guitars. Love the impedence pot, cymbals sound great! One thing is I don't have continuity with zero volts and the case, no noise, should I scratch off some paint where the dc jack connects?
Peter Kuchar

[Joe Malone]

My voltage was running a bit high. 47.5 volts in and 24.75 out or so on all 4 pres', So I dialed the volts back to about 46.5 in and around 24.33 out and that was enough to get the power supply out of hiccup mode. now all 4 preamps are running smoothly and sounding great! I was going to use them on my 4 toms, now the highs are so smooth they sound great on overheads and guitars. Love the impedence pot, cymbals sound great! One thing is I don't have continuity with zero volts and the case, no noise, should I scratch off some paint where the dc jack connects?
Peter Kuchar

Cool great to hear you got them all going and like them

If you are having trouble with the dc barrel linking the chassis to 0v. We just add a wire from the dc connector 0v to where the side bolts onto the back panel next to it so the 2 screws there link it to the chassis. If the BA4 rack is bolted into a rack frame then it will also get chassis ground from the other gear in the rack so usually it doesn't matter as look as the audio has good quiet noise floor

[caoimhin]

Building a pair of BAD with JLM14 and JLM2503, and I want to add a 'ratio switch' for the output transformer for 1:1, 1:2, 1:3.

Can I do an idiot check that it's o.k. to just use a 3 position rotary switch like this?:

RatioSwitch.jpg

[Joe Malone]

Building a pair of BAD with JLM14 and JLM2503, and I want to add a 'ratio switch' for the output transformer for 1:1, 1:2, 1:3.

Can I do an idiot check that it's o.k. to just use a 3 position rotary switch like this?:
RatioSwitch.jpg

Yes that is correct

[caoimhin]

Photos or it didn't happen, isn't that what they say? Delighted with how this turned out, thank you so much Joe!

[caoimhin]

up close

[Joe Malone]

Photos or it didn't happen, isn't that what they say? Delighted with how this turned out, thank you so much Joe!

Wow that looks great Nice knobs and layout.
Great to hear you got it all working