SSL 4000 G Bus Compressor


#1

SSL 4000 G Bus Compressor

INTRODUCTION
Making mixes sound bigger, with more power, punch, and drive, the SSL G brings cohesion and strength to your mix without compromising clarity. To this day it remains a key element of the SSL sound and has been featured on countless classic recordings. With simple, intuitive controls and transparent compression characteristics.

HARMONIC ANALYSIS
To analyse the non-linear behaviours of the SSL 4000 G Bus, I ran a 100 Hz sine wave through the plug-in at various settings.

100 Hz sine wave at -12 dB passed through G Bus at Unity

100 Hz sine wave at -12 dB passed through G Bus Output +12 dB

100 Hz sine wave at -12 dB passed through G Bus +15 dB

The G Bus has strong third order harmonics, which are associated with richness and depth.

The second and forth harmonics are boosted slightly when driving the output; DC is also reduced, perhaps due to hitting the output transformer a little harder?

SATURATION CHARACTERISTICS
For this test I ran drum and synth loops through the G Bus at various settings. I have compensated for level so that the loops peak at -1 dBFS for maximum resolution of the waveform in Pro-L.

Dry Drum Loop

Drum Loop passed through G Bus at Unity

Drum Loop passed through G Bus Output +12 dB

Dry Synth Loop

Synth Loop passed through G Bus at Unity

Synth Loop passed through G Bus Output +12 dB

Very smooth and subtle saturation characteristics; driving the output has a slightly more agressive tone.

AUDIO EXAMPLES
SSL G Bus Drums 4dB Compression 300HzSC Mix50%.aif (1.3 MB)
SSL G Bus Drums Dry.aif (1.3 MB)
SSL G Bus Drums 4dB Compression.aif (1.3 MB)
SSL G Bus Drums 4dB Compression 300HzSC.aif (1.3 MB)
SSL G Bus Drums Unity.aif (1.3 MB)
SSL G Bus Drums Output12.aif (1.3 MB)
SSL G Bus Synth Dry.aif (1.3 MB)
SSL G Bus Synth Unity.aif (1.3 MB)
SSL G Bus Synth Output12.aif (1.3 MB)

FREQUENCY AND PHASE RESPONSE
Lets take a look at the G Bus frequency and phase response at various settings
What I am looking for is the frequency and phase response of the plug-in at unity and if driving the output circuit changes this relationship.
Spectrum Colours
Yellow - noise generated by the plug-in analysis software to analyse the plug-in
White - frequency response of the plug-in at that particular setting
Red - phase shift of the plug-in at that particular setting

G Bus at Unity

G Bus Output +15 dB

The G Bus has a very linear frequency and phase response.

At unity, frequencys below 20 Hz are rolled off; when the output is driven, frequencies below 30 Hz are boosted a couple of dB. This does add a little bit of power in the low end.


#2

Thanks Paul! Very nice explanation!


#3

Amazing again, Paul. Thank you for this! What is that little bump of energy in the sub range in the screenshot?


#4

Thanks guys

The mkii sounds tight, punchy and open sounding, when compared with the legacy version, the legacy version sounds dull and lifeless, although I do like the sound of the legacy, the mkii is far superior. I could still see uses for the legacy on extremely bright mixes.


#5

Used this today, one word… WOW!


#6

Paul, awesome post. I was about to delve into similar research, nowhere near as deep as what you did. Absolutely wonderful job.


#7

hey there!

you missed the HR knob. i believe that would change something also on pictures :slight_smile:

and i found this plug to reduce some HF content from my tracks when used as buss compressor. pleasantly, but too much for my taste…

…still little puzzled about it :slight_smile: as with almost all uad plugins, haha… (will that ever change? :slight_smile:


#8

I would have had the HR set to 0 when doing the analysis.

I know what you mean, I had some issues with high frequencies at times. M/S configuration alleviates this.