Neotek Series Early Channel Strip DIY

[alexc]

Hi All

Just doing some maintenance on a channel strip racking I did a couple of years back of a Neotek Series 3  (it could be a series 1 or 2) channel.

It was an early one - no connector, just a bunch of flying solid core leads.

I REALLY like solid core leads! I wish I had more of them.

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I racked in with a JLM psu and added a bunch of cheap'n'cheerful 'repurposed' stuff, as is my wont

At the front end, I added :

- jensen mic traffo specifically for putting in front of pre-existing chip mic preamps
- haufe line in traffo
- Igor 'universal preamp' DI  module

At the back end I added :

- beefed up the girly strength post-eq direct output with a Lawo DOA and Haufe 1:2 traffo
- added 2x balanced line amps to the stereo bus outs : transistor driver and Altronics 1:1 traffos
- added 4x balanced line amps to the aux bus outs : AKM 5532+1:2 traffo modules

As well as adding :

- led VU meter
- JLM 'Mac' Opto compressor  (full wave recitified dual vactrol side chain/blend module)

Now this channel strip was an 'inline' architecture, with some overly complex select logic which was all burned up, so I untangled all the routing and added a 'sum amp' for the 'tape return' and whichever of the 'mic/DI' or 'line' is selected by Neotek switch.

It also had a 'record out' which I kept - a piss weak chip output.

I put the compressor just on the 'input' signal, and then summed that with the 'tape return'.
It uses the 'post fader amp' as the vactrol's 'shunt resistance coupled make up amp'

(the JLM mac is just a sidechain/blend unit - you need some amp to drive with it)

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WHY I hear you exclaim?

First and foremost for the hell of it, and second because I wanted to use this as a 'guitar distro box'

ie. plug in a guitar to the DI (or mic or line!), and send to an effects box via the 'rec out'

Main signal goes to AWESOME eq, 4x full strength balanced aux outs for distribution purposes
Then to compressor for very nice limiting, LA4 style

Take the effects box as 'tape return' and mix it with the Neotek pot with the above

Of course, there is a 'flip' switch to .. flip .. the main and tape return inputs!

Finally,  summed signal goes to :

- full strength mono  output  for desk/daw
- full strength stereo outputs for tube monitoring stereo (low input sensitivity) 7W SE 6L6 amp + speakers

Here's an inside pic

 

[alexc]

Now when I got the thing, is was serious borked, burning psu regs etc and all the logic was completely nfg.

I *did not* have a schematic - the nice boys who handle legacy Neotek wanted a bomb for it so - no go.

I had to reverse engineer this thing, untangle all the logic, which used a truck load of fet gates and analog switch/mux.

It also has the weirest eq routing, aux routing and just about everything else!

After all that, I re-routed/crochet'd it back again  the way I wanted and added all the stuff!

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At the conclusion of all that - it works great as a guitar hub, able to handle direct, mic and feeds from other gear, as well as driving a universe of sources. 

 

[alexc]

The mic pre is nothing much to sing about - the usual couple of front end 'low noise' (hah!) transistors coupled to a mc______ opamp

The line in has a diff opamp on the same quad package, seperate and selectable which works OK.

The rest is more of those mc___ opamps, a few tl074s and 5532s.

EQ is stonking - great for acoustic guitars especially and taming recalcitrant electrics.
It really is like a 'cheap and sh**ty neve' But with 5 deck pots 

Even Mr Porter shied away from that implementation!

Limiter is really, really fine - very transparent but very satisfying - especially on acoustic git.
A bit too small - continuing JLM Audio's fascination with everything .. small.

I do love it actually - at the end of the day it's quite transparent if the front end is not pushed too hard and the beefy line amps take care of the rest!

I think the whole thing ended up around 550aud of which nearly 200 was shipping.
And it weighs  a mere 5kg or so. Almost 'not there'!

Next I have some more time, I plan to rework the fixed limiter 'blend' ratio to be more like the 'What' comp.

When I did this in 2009, I didn't really understand that aspect, but since I did the 'What' comps with it's 'april resistor' blend thing I follow it much better. I would like more and less .. smash!

Cheers