JLM AUDIO

Can sum several balanced inputs into AMP HEAD with 10k resistors. (I will do a drawing of this ASAP) Is this just a typical passive resistive summing network in front of the audio inputs, or are we talking an ACN somehow? Each balanced in is a H pad made from R1 to R4 10k and VR 10k log pot to the ...

Holger wrote:Regarding R1 on the little PCB: what value goes where (lots of holes)?

V8 PCB takes 1 x 9 pin 47R SIP 8 buss resistor pack. Pin 1 has a dot on the side of the ressistor pack and is the square pad on the PCB which is the common end of the 8 buss resistors.

Why not completely overdo it? I see a JLM channelstrip before me!!! Like this: first stage of the dual99v - passive EQ network - second half of the 99v - MAC opto comp - Dingo kit - output. Maybe I could even take a 1:1+1 output transformer, pop it in between the 99v out and the opto input and have...

Mono and mute options can be added with one center off toggle switch and no other parts wired across the 4 outside pot terminals. (I will do a drawing of this ASAP) Hi Joe, any news on this or a schemo maybe? I guess by using a center off toggle switch it must be connected after the de-balancing ci...

Add below info to the first post on this thread. The VUPPM has all parts values on the PCB overlay and is a normal build from the lowest to tallest height component. Only component changes that need to be done depending on power supply voltages are listed in the table below. R13 & R14 changes are to...

Brilliant! :D Ok, so now I am measuring 48 volts on the center pin of the BD681 but 46 on the Emitter pin (pin1). All pins that should read 48 read 46. Except the Phantom power, that reads 48. All the locations that should read 24 read 23 volts. The other BA without the soft mod, readings are fine....

A little update: both of my dual99v are working fine and sound good - better than my vintage Telefunken V672, even though I have the best version they built back then. As long as both have headroom, they are good, when the V672 hits it can get ugly soon. The dual99v just handles it like a champ. If...

HI Scott From the big photos you sent there seems to be a solder short between the 2 pads in the red circle below. The plated via hole that has solder in it shouldn't but must have happened when soldering the opamp socket next to it. The via is +48v and the bottom pad of the zener is 0v. This would ...

My BA JLM99V with JLM14 is causing the power supply to go into protection mode. I'm using the 48v 25w 520mA SMPS and have applied the soft start mod. One thing I was not sure about was the BD681, the front (of the bd681 the side with the markings) should be facing out from the pcb? Hope the pics ex...

Hi Joe- I've got a funny little issue I can't figure out on my Powerstation. It's set up to run 3x 24v lines, with C1 and C2 removed. When testing outside of it's case, it's working perfectly with no issues whatsoever. OK However, in it's case, it's blowing fuses instantly on start up. I initially ...

Yes, I have no doubt your circuit is good! 8) I just wanted to throw one together quickly to play with, and thought/hoped you may know off hand what I did wrong based on my symptoms. Yep that is fine. But since it is not working at all it is hard to work out what is wrong as there are to many optio...

I have breadboarded this circuit, twice, but cannot seem to get any meter movement unless I place my audio line source (line output of a tape deck/also tried headphone output of mp3 player) directly into the +/- inputs of the opamp. I am using a 34mm meter (I beleive it to be 500uA). Anyways, not s...

Would there be enough parts and traces easy enough to cut / re-route on this board to convert to a dual unbalanced in to dual unbalanced output unity (or some small amount like +6) gain buffer? Yes simple to do and you do not need to cut any tracks BUT it would be nicer and easier done with 2 x Reg...

Can the variable gain range be changed to a more full range selection, such as a swap from 5K to 20 or 25K value? Gain range can be changed by changing the 1k8 and 15k resistor to different values but this is a gain function so it no going to be a like a volume pot with full off position. If turnin...

Joe I will be using OPA2604 .Should I also run the rails at +- 18v or bump up to +- 24 v(raise elec cap volts to 50) +/-24v is good with the OPA2604AP. Caps still only need to be 25v types. The kits have 35v electros in them Also anything else I should know about using this circuit with the OPA2604...