JLM AUDIO

Hi Joe, I CHanged the Regs and everything works fine now. Thank you for your help. I have a question too. In the power plant page, its written that can feed 4 modules. Even those telefunken or neumann cards with 2 channels per module?? Thank you! Cool great to hear you got it working ok. As long as...

I think i worked it out by myself. There's a huge pad on the input, 40db. It's extremely hard to read from the schematics. What i ended up doing is this. A new pad in front of the input transformer (Lundahl LL2603 1:1) thats attenuating 25dB.The secondary of the 2603 is terminated via 2k plus 1,6nf...

Hello Joe, Oh ! Then I have decalibrate my new VUPPM :oops: I'm not in my studio this week so I can't recalibrate it now but when I try the first time, my problem was that the VU/PPM trimpots had no action. (The green VU level didn't move) Is it possible ? I will try again ASAP and tell you ! Thank...

Hello Joe, I just received your wonderful VUPPM 500 Meter, thank you very much ! I have tried to calibrate the VUPPM as describe : Send in 1k tone at 0dFS or +18dBu to 500 Input for left and Output for right. Set mode to VUPPM mode RED PPM with GREEN VU over the top. Adjust Left and Right level tri...

Hi thanks for your reply. I cleaned the pcb with isopropilic, but is dificult to take a picture showing the traces, cause it shines with the light I hope you can see something. So I have to change one of the regs, or better both? one or both The trim for the 24v now doesn't works, I dont know if I ...

Oh, I thought I sent it attached. Let me try again The bottom of the pcb needs a good clean with isocol or iso prop and toothbrush to see properly but I can see that one centre leg on the trimpot has never been soldered so will not work. Since the 3 x 120R burnt the 48v reg is likely to be dead sho...

Hi! Im having some problems with my second power plant. Some 120r resistors got burned and I changed them with new ones. Now the 48v rail marks 24v And 24v. Rail marks 35,6 v. Im sending you a photo if hepls. Thank you very much! Ok yes attach some photos of the top and bottom of the pcb here or em...

Hi Joe, Here is my sad tale: I built a v3 AC/DC with 48v and +/- 28v and it worked great for many months powering a DIY mic pre. Then one day it blew a mains fuse, I disconnected from the mic pre, replaced the fuse, and 48v had turned into 5v. I then replaced R7 because it was blown up and D10 beca...

Hi Joe, Here is my sad tale: I built a v3 AC/DC with 48v and +/- 28v and it worked great for many months powering a DIY mic pre. Then one day it blew a mains fuse, I disconnected from the mic pre, replaced the fuse, and 48v had turned into 5v. I then replaced R7 because it was blown up and D10 beca...

Perfect. This inductor should be as close to the -in as physically possible. Yes, that's where I put it. 8) Do you have a copy of this sections schematic? Sure: ACA_Booster.jpg Everything, including the dotted part, is actually there. As in the summing section I have used bipolar caps and will remo...

Thanks Joe. I thought offset might be the problem. Since adding output caps is not really an option I guess I'll use modern op amps after all... Audio path Cap is 1uF MKT polyester not ceramic. If lower input impedance is need then cap needs to be increased to 10uF etc so Non Polar electro will be ...

Thanks Joe. I use a 20uH inductor at the moment. Self-wound with a ferrite bead. I couldn't detect a change of the frequency response in the audio band. Perfect. This inductor should be as close to the -in as physically possible. BTW, what about the buffer stage after the fader? In the feedback pat...

Hi Joe, looks like this is exactly what I need as balancing/output driving stage for my discrete multichannel DAC! :D I'd like to use NE5532 (got old Signetics ones that I consider the best sounding op amp out there), any reason why they wouldn't work here? What can you expect WRT to SNR and THD? T...

Cool, thanks! I forgot to add an inductor to the schematics. I added it between the input cap and the op amp's inverting input to reduce RF reaching the summing amp and increase stability. This shouldn't make a difference WRT to implimentation, I think. Yes inductor is good idea as long as it is sm...

Thanks Joe! I had a JLM99V in one of my BAs but it got destroyed accidentally. I remember it sounded better than all the other op amps I've tried... The console has 32 channels + 8 returns, so 40 get summed to each side of the master bus in total. Ok so a gain of 27 max which is easy. Also C15 will...