Langevin AM4a Vintage Recording Console Mixer Electrodyne Quad Eight

One of a kind, fully operational and exceptionally rare 1968 Langevin AM4a. Class A circuitry. 12x channels, 4x bus outputs, 8x line inputs. A total of 20 inputs and 4 aux returns for mixdown.

Console dimensions: 46”w x 30”d x 8”h

Console weight: 150 lbs

12 rotary fader channels w/ mic pre,EQ and reverb send

8 ch line level mixer with Cinemag input transformers

4 bus outputs

4 reverb send and return

2 ch  Bus line input

This restored and modified Langevin is the result of years of work between the mods and additions. All work was done by Rob Harvey at World Pro Audio in Los Angeles. Over $10,000 of work and mods done to this unit which was working when purchased, but needed a lot of TLC. No shortcuts where taken and at all stages, only the best and most sonically pleasing components where used after testing. Pages and pages of notes and photos are available to show and explain all mods and upgrades thru the whole process. 

The EQ is mil-spec stepped switches, 2 band, +/-12db for each band, 3db increments. The high frequency selection points are 3K, 5K, 10K - or the middle frequency between two points (if you select both switches). The low frequency points are 50, 100 and 1K - or again, the middle frequency between two points. For example - if you select both 5K and 10K you will boost at 7.5K. All the EQ points are shelving with the exception of the 1K EQ which is a peak

A short list of some of the work from WPA for this Langevin AM4a console:

- All pots and switches and connectors given deep cleaning: WPA Brown Stuff (oxidation remover), CRC QD Electronic Cleaner, compressed air, MS Contact ReNu and Lube

- Xlr rear panel fabricated for all inputs and outputs replacing a messy XLR snake.

- Additional power supply decoupling resistor and capacitors added to each module to reduce crosstalk via power supply rails.

- All repairs as needed, for instance faulty transistors replaced, broken connectors replaced. Everything gone over with a fine tooth comb.

- All electrolytic capacitors replaced.

- Incandescent lamps in each channels circuit replaced and installed in those missing them.

- 8 Line input transformers added ahead of already existing line input pots (upgrade of existing passive mixer). Replaced mute toggle switches on all 8x mixer channels

- 4 bus modules modified for lower hiss and hum: first gain stage changed to Jensen JE16A transformer followed by Hardy 990.

-Switch added on 4 bus modules allowing bypass 1 gain stage and pot in Master module. When bypassed, Board Master (4 ganged master) still works. Sonic difference when bypasses is slight improvement in tightness of bottom and noticeably brighter, yet frequency response remains the same, so that transient handling is improved.

- Some changes to chassis and summing bus grounding to lower hum

- Transformer balanced and switchable stereo bus input (bus 1&2) to accommodate any 2 channel input, such as output from another mixer.

- VU meters calibrated so that +12 db = 0vu (8db hotter than normal studio level of +4db). Console sounds best at hotter level. Best not to let meters go over 0vu… meters dancing around straight up is a pretty good rule of thumb that keeps signal hot while allowing for moments when signal is a bit hotter.

* End result: Better than a new AM4, better sounding than almost anything in terms of pro audio class A warmth.
Couple things I'd like to mention for transparency: 
- On channels 1,4 & 11 there is a little green light above the main fader knob that will need replacement. Everything else on these channels functioning.
- Some of the functions that were probably original to the console when it first came out were not in use when I purchased it. This includes SOLO, 8x AUX/NORM selection switches in alcove near VU meters... and whatever the switches and buttons on the thin panel at the far righthand side were for. Room for more mods for sure- I kept it simple and straightforward.