Neve 2254, limiter section usefull or not?

[Spencerleehorton]

well so far no limiting? i was mistaken before, it wasnt working, im obviously missing something as dont get any limiting, just compression?

 

[Rob Flinn]

If the limiter is working you should be able to set the threshold to say +4dB and then wind a very much larger signal into it and the output will remain at +4dB. i.e it holds the signal output at the level the threshold is set to.

 

[Spencerleehorton]

I’m not getting hardly any level drop when dialling in the limiter threshold?
Need to look at the b192 as the waveform ain’t right

 

[Rob Flinn]

I’m not getting hardly any level drop when dialling in the limiter threshold?
Need to look at the b192 as the waveform ain’t right.

Maybe this is obvious but if you set the threshold to +4dB, which I believe is it's lowest setting, you will need to put a signal greater than +4dB into the box for it to start limiting.

 

[Spencerleehorton]

Ok no problem, I’ll get a good level into it and test but at the minute when probing I can’t see it keeping level at the same level.
I’ve changed the threshold to just a 1k pot but works just the same. Wasn’t clear that I had the threshold control wired correctly with the lorlin? Will post drawing just to check I got this right!!

 

[Spencerleehorton]

Putting 5v @ 1k in from gen and not getting any output drop?

 

[Rob Flinn]

You should meter/scope the side chain signal to see if it increases when you ind more signal level into it.

 

[Spencerleehorton]

i can see a drop on the meter when i set it to output and i probe on the output of the transformer into the limiter sidechain but when i scope on output there is no affect to signal at all? on the 2254/E schematic there does show a connection from BA283 on F to P? is P a connector on the case or should F connect to P on BA283?

 

[Rob Flinn]

i can see a drop on the meter when i set it to output and i probe on the output of the transformer into the limiter sidechain but when i scope on output there is no affect to signal at all? on the 2254/E schematic there does show a connection from BA283 on F to P? is P a connector on the case or should F connect to P on BA283?

You need to trace the sidechain signal from the transformer through the sidechain circuit.

 

[Spencerleehorton]

Tracing waveform through side chain waveform looks cut in half

 

[Spencerleehorton]

Both channels now act the same so i must be missing something obvious!!!

 

[Spencerleehorton]

only signal i see on b185 limiter section is J and K, everywhere else voltage is rather than signal?

 

[Spencerleehorton]

Not knowing this compressors limiting section very well, should I see a normal waveform present on J and K of b185?

 

[Rob Flinn]

You need to trace the sidechain signal from the transformer through the sidechain circuit.

The waveform for the sidechain should be rectified, only going positive (I think in this case). If you input a sine wave at some point the side chain should flip the neg going peaks to be positive.

 

[Spencerleehorton]

Well, waveform on J and K look like wavetable waveforms!!
So something ain’t right with b185
Will check all connections and voltages and see if I can spot the problem as I’m pretty sure I’ve made all connections.

 

[Spencerleehorton]

I also try another transformer as it could be these transformers I’ve wound which are a problem!!

 

[Spencerleehorton]

Tracing the signal through the amp stage of the b192 the signal gets to square wave at R4 / C6 / base of TR2.
Probe on P and waveform looks distorted so could be txf which is effecting it or possibly TR3?
S output looks inverted but clean rectified waveform.
Will disconnect P connection and see if waveform is not distorted

 

[Spencerleehorton]

Here is the inverted waveform when txf attached, no compression , no threshold to compressor. Limiter controls do nothing?

 

[Spencerleehorton]

this is how I wired the limiter threshold lorlin

 

[Spencerleehorton]

And this is how I e wired the 3 way switch to get fast/slow and off for the limiter