JLM AUDIO

I can get any combination of 3 boards working with the GS25A48-P1J 25W PSU as well as the GSM40B48-P1J 40W PSU. Whenever I add a fourth board (any board, I've tried different combination) it goes into protection mode. Voltages across the 10R are 0.350, 0.361, 0.284, and 0.285. All boards have been a...

I got the 48v 40w SMPS power supply but it did not help at all. The unit has been going into protection mode (cycling green power LED) with any more than 2 PCB's attached. It doesn't matter which PCB combination I used, with 3 or 4 attached it would go into protection mode. This is true with the 40w...

First thing make sure the 4th module is working and powers up fine by itself and is not just faulty and causing this problem? Otherwise best is just remove red cap and nothing else if you are using a 48v 25w SMPS to run 4 x BAN. If using 48v 40w SMPS nothing should need to be done. Thanks, Joe. I'l...

Yeah you're right Joe. My mistake. I had read a couple times we probably didn't need the soft start mod for the new PSU's so I didn't recognize the hickup protection for what it was. To confirm, do you mean remove the cap I crossed off in red, or the one circled in blue? Would I need to put a jumper...

Looks like my challenges with this build aren't quite done yet. I finished the fourth channel (using 2SA1804 transistors - accommodating for their different pin configuration appropriately). Somewhere along the line testing this fourth channel, I started developing a bizarre fluctuation in the volta...

To summarize, my problems appear solved after corresponding with Joe via e-mail, and the explanations are as follows: 1) Fluctuating noise floor - This has resolved to normal limits after adding a third channel to the build. It appears this was a shortcoming of the 48V adaptor that causes it to prod...

Can you please check your IC pinout as pin 4 should be at 0v on both IC's and pin 8 should 48v one IC and about 40v on the next? Otherwise you have the ICs in backwards Sorry Joe, you're right. I rechecked and I have my ICs oriented correctly, but I reversed the pin numbers when I was writing down ...

Do not add 0.1 across the opamp power pins as this will increase high freq SMPS noise by injecting SMPS noise into the half rail in the BAN. Okay. Thanks. I've taken them off. It was a problem before I added those though anyway. Does the BAN case have 0ohms to 0vdc on all panels of the case? I'm re...

Further testing: I just completed a second channel. This one is measuring normal ~25 V at TP3. But it's still got the fluctuating noise floor. I'm starting wonder if I have two problems. 1) First channel measuring abnormal ~38 V at TP3 when trimmer turned half way (for unknown reasons) 2) Faulty pow...

Here is a screencap of what the waveform looks like when the noise bumps up to around -32 dB every so often.

Here are some pics of the board as it is. The only "mods" are now that I am using a SSM2212 mounted on a SOIC8 to DIP8 board via the underside (which seem to be passing sound and should be a straight substitution so I presume they're working fine). And I now added 0.1 uF bypass capacitors to the opa...

I added 0.1 uF bypass capacitors from Pins 4 to 8 on both opamps with no improvement.

It's a BAN4 project in the case you sent to me, with the 48V 0.52 amp 25W max output adapter you provided. So far I've only mounted one card. With no input xlr cable, and the pad switched on, the noise floor idles around -50-60 dB, but it constantly fluctuates up and down by around 5 db in either di...

Another thing: With the gain of the preamp to max and no mic attached (just a loose XLR cable), I'm getting some pretty good hum which is reading at -51 dB in my DAW. Is this normal? 2 MB WAV recording: http://www.filedropper.com/nomiclidlooselyon The chassis is currently still grounded via the lead...

Hey Joe,

My kit is the BAN with no transformers and two OPA2604's. Can you please explain what these two trimmers are doing so I can better understand the need to get them right?