Search found 31 matches

by living sounds
Sun Jun 05, 2022 6:23 am
Forum: JLM Audio Kits
Topic: BA BA2 BA4 BAD Dual99v Build Thread
Replies: 376
Views: 862298

Re: BA BA2 BA4 BAD Dual99v Build Thread

Thanks Joe, but that wouldn't explain my measurements. The signal is reversed at the primary, at the trafo input. So trafos don't even come into play here.
by living sounds
Mon May 30, 2022 9:04 pm
Forum: JLM Audio Kits
Topic: BA BA2 BA4 BAD Dual99v Build Thread
Replies: 376
Views: 862298

Re: BA BA2 BA4 BAD Dual99v Build Thread

Was the phase flipped between BA revisions? I've got two revisions of the BA board. All wiring was done correctly, but the signal is inverted at the trafo input on one channel. Can you let me know or send me a photo of the 2 pcb versions as there are many. And what input transformers are fitted? An...
by living sounds
Sat May 28, 2022 7:07 pm
Forum: JLM Audio Kits
Topic: BA BA2 BA4 BAD Dual99v Build Thread
Replies: 376
Views: 862298

Re: BA BA2 BA4 BAD Dual99v Build Thread

Was the phase flipped between BA revisions? I've got two revisions of the BA board. All wiring was done correctly, but the signal is inverted at the trafo input on one channel.
by living sounds
Fri May 06, 2022 2:39 am
Forum: JLM Audio Kits
Topic: Correct grounding procedure Baby Animal
Replies: 1
Views: 1746

Correct grounding procedure Baby Animal

Hello, I had pin 1 connected directly to audio ground before, but now have rewired my unit to followed the Rane way of doing things in my build. Meaning, pin 1 of the input goes directly to chassis and connects to PSU ground (48V inlet) through the chassis. Same for Pin 1 of the output connector. Th...
by living sounds
Wed Oct 30, 2019 7:03 pm
Forum: JLM Audio Kits
Topic: JLM99V as summing amp
Replies: 12
Views: 19809

Re: JLM99V as summing amp

Yes will work fine. But I wonder why no one has recalculated all the resistor values in this whole design as the noise floor and crosstalk could be much improved without any real change to the circuit. It's an exact copy of old API circuitry, so authenticity is the paradigm. :D But I only care for ...
by living sounds
Tue Oct 29, 2019 11:31 am
Forum: JLM Audio Kits
Topic: JLM99V as summing amp
Replies: 12
Views: 19809

Re: JLM99V as summing amp

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...
by living sounds
Tue Oct 29, 2019 11:22 am
Forum: JLM Audio Kits
Topic: Tardigrade Build Thread
Replies: 9
Views: 28605

Re: Tardigrade Build Thread

Joe Malone wrote:
The 1uF mono cost about the same as the 0.1uF mono in bulk so we use them as you can get super low esr much closer to opamp power pins and few 1uF add up to electro size uF. So makes most unstable opamps super stable.

Very interesting, thanks!
by living sounds
Tue Oct 29, 2019 12:27 am
Forum: JLM Audio Kits
Topic: Tardigrade Build Thread
Replies: 9
Views: 28605

Re: Tardigrade Build Thread

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 b...
by living sounds
Tue Oct 29, 2019 12:18 am
Forum: JLM Audio Kits
Topic: JLM99V as summing amp
Replies: 12
Views: 19809

Re: JLM99V as summing amp

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. BTW, what about the buffer stage after the fader? In the feedback path it has a 47k resistor with a 47pf cap on top. Would this be a good candidate...
by living sounds
Sat Oct 26, 2019 12:20 am
Forum: JLM Audio Kits
Topic: Tardigrade Build Thread
Replies: 9
Views: 28605

Re: Tardigrade Build Thread

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? Al...
by living sounds
Fri Oct 25, 2019 11:29 pm
Forum: JLM Audio Kits
Topic: JLM99V as summing amp
Replies: 12
Views: 19809

Re: JLM99V as summing amp

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.
by living sounds
Fri Oct 25, 2019 11:05 am
Forum: JLM Audio Kits
Topic: JLM99V as summing amp
Replies: 12
Views: 19809

Re: JLM99V as summing amp

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.
by living sounds
Fri Oct 25, 2019 3:08 am
Forum: JLM Audio Kits
Topic: JLM99V as summing amp
Replies: 12
Views: 19809

Re: JLM99V as summing amp

Thanks Joe, here are the schematics. The channels are summed through 22k resistors. Consolesumming.png I would remove R14 to account for the DC offset at the output of the JLM99V. Signal path / DC blocking caps are bipolars, so no need to change anything there. How would you describe the sound of th...
by living sounds
Thu Oct 17, 2019 11:29 pm
Forum: JLM Audio Kits
Topic: JLM99V as summing amp
Replies: 12
Views: 19809

JLM99V as summing amp

Hi Joe,

does the JLM99V make a good summing amp? I'd like to use it in the CAPI 2-ACA for this purpose. I would remove the resistor following the op amp, so there is a cap in place to prevent DC from magnetizing the transformer.

Thanks!
by living sounds
Sat Oct 18, 2014 3:45 am
Forum: JLM Audio Kits
Topic: A2D
Replies: 43
Views: 169640

Re: A2D

Thanks Joe! I'll report back when I've got the JLM14 installed.