JLM99v opamp

 New JLM99v +/-16v version

 JLM Go Between & DI PCBs &  Kits

 JLM1:4 Mic Input

 JLM1:1:1DC output


 JLM Dual 16mm 10k Reverse log pot with 41 detents.


JLM99V Opamp and PCB & Kit

  • New Dual99V front panels have variable impedance control between gain and output controls.
  • Kit is now built on the BAD PCB to make it much quicker and easier to build. See New 2009 overlay further down this page.

Links to some of the full Forum threads

JLM99*MB is 5.45" (139mm) x 2.3" (59mm).

Above is the JLM99*MB PCB for the JLM99V which can take several transformers from manufacturers like OEP, Lundahl & Jensen. The board also has NE5534A DIP8 sockets so it can be fully tested with cheap IC's before installing the 99V. The PCB can be used for building the simplest NE5534A or 99V circuit or all the way up to dual 99V with dual DC servo. PCB has provision for 3 pushbuttons switches or relays for 48v, PAD & Phase on one edge. The relays run from a constant current source so more relays can be easily wired in series for extra features without making noise on the audio power rails. The small PCB is the JLMSWMB which takes three toggles and LED's to control the relays if used by 4 wires.

JLMSWPCB is for controlling the JLM99*MB 5v relays if fitted. The relays all run in series from a constant 35mA current source to stop power rail spikes . Two of these PCB's can be run in series to control up to 6 functions.

JLMSW PCB is 1" (25.4mm) x 1.3" (32.7mm) with toggle holes spaced at 0.5" (12.7mm). 





The terminal blocks have tongue and grooves which lock them together on there sides. So 2 x 2 way can make the 4way and 3 x 3 way can make the 9way. If you don't join them together they will sit uneven on the PCB. 

Normal 8 pin DIP IC sockets and comp cap for NE5534A etc can be left on the PCB if PCB pins are used for the JLM99V

If you can not open the PDF's below you will need Acrobat reader 7.0.


Input Transformers the PCB can take directly are

  • JLM1:4 (comes with 2 x 3mm bolts and 2 x plastic bushes which hold the transformer 1mm off the PCB)
  • OEP A262A2E, A262A3E, A262A6E, A262A7E
  • Lundahl LL1538, LL1538XL, LL1576, LL1577, LL1578XL.
  • Jensen JT-11K8-APC, JT-110K-HPC, JT-115-EPC, JT-MB-CPCA
  • Remember to mount all transformers with a gap of about 1mm under them so any metal shields do NOT short out any of the PCB Pads.

Just for clarity
The only thing the Deane Jensen 990 Design and mine share is the pinout configuration. The JLM99V is more like a Neve Class A Preamp on major Steroids. It is a pure path device with the signal path only travelling through three transistor junctions. It has gain limited to about 60dB with no feedback applied. When setup right the THD with feedback is 0.005% at normal operating levels heading up to 0.5% 2nd Harmonic as its output swing reaches closer to the power rails. It has a 1v DC offset on the output due to the -input of the opamp being an emitter input. It runs best on +/-34v but can run on +/-24v.

200 x JLM99V's just before being epoxy potted and final testing.

New JLM111DC Output transformer. Can be used for Neve LO1166 or API 2503 type DIY projects. The transformer is DC gapped and has 3 identical 150ohm windings that are trifilar wound. So can use as 1:1:1 or 1:2 or 2:1 applications. It is physically the same size as the LO1166 except the the top terminal plate is narrower so it will fit on its side in 1 unit high racks which have a 38mm internal height. Each winding has its connections opposite each other and one side is marked Red+ and the other Yellow-. 

  • For 1:1 use any winding for primary and any other winding for secondary.
  • For 1:2 you could use winding 1 for primary and wire +2 to -3 and take  +3 & -2 as the secondary.