X-treme Multi-Band Compression  

"The Multi-Band X-Factor!"

Multi-Band Compression, what the hell is that??

Well simply, Multi-Band Compression (also known as Split-Band Compression)
is the best way to control the dynamics of a mix by separating the frequency spectrum
into 3 or more bands, individually compressing those bands,
then recombining the separated bands into one mix.

The're allot of benefits to using this method over Single-Band (aka Broadband) Compression.
With a Broadband Compressor, you can really only choose to change the dynamics
of a target area of frequencies by using the Threshold, Attack, and Release controls.
That´s ok if you are targeting the high frequencies for de-essing as the Attack and
Release controls can usually be set to affect just those frequencies and
pass the Lows and Mids virtually untouched.

Well, what if you need to change the dynamics of the Lows and Mids as well?
If you slow down the Attack and Release controls to allow the
Low Frequencies to be processed, you are now also affecting the Mid and High Frequencies
which could take out some of the brightness, clarity, and detail of the mix.

With a Multi-Band Compressor, you can adjust the compressor settings to
optimize each band without affecting the others. For example, with Voice you are
able to adjust the Low Frequencies to remove boominess and add a nice smoothing affect,
the Mids for more density with clarity, and the Highs for sibilance control and de-essing.
This creates a mix that has deep, well-defined low frequencies, a powerful midrange,
and crystal clear highs. This type of mix will also have what we call
frequency separation, which Sonically sounds like the Sound Stage is
opened up with immaculate detail, kind of 3-dimensional.

Sounds too good to be true? Well, the learning curve is a bit steep and
takes a while to develop an ear for this type of processing.
Most Recording Masters know the potential for these units, but still don´t
implement them unless they are trying to "fix" an already Mastered mix.
You have to be careful with it because you can "kill" a good sound by over processing.

In the Radio Broadcasting realm, this type of processing has been used for
a long time in some of the best AM Audio Broadcast Processors like the Orban Optimod AM.
Their performance is legendary and can be adjusted by the engineer to maximize the
signal for the best reception in all conditions for a wide range of program material.

We have taken this theory and are applying it to SSB, actually eSSB.
If set up correctly, you can and will have a spectacular full and
well balanced sound with enough density to sound terrific even if the
receiving station is listening in a narrower filter then the bandwidth your transmitting in.


There are some affordable digital units out there that perform very well,
and some unaffordable units that perform extremely well.

At the top of our affordable list is the TC Electronic Triple-C.
These can usually be picked up for around $200.00 - $300.00.
They were over $1000.00 when they were new. The only thing to look out for on
these units is that the Display has a tendency to go partially blank on them.
The Behringer DEQ-2496 is also a good unit, although they call there
Multi-Band Compressor a Dynamic EQ (DEQ) which is basically the same exact thing.
The only difference is in the way the frequency and gain structure is configured.
The Behringer DSP9024 is an oldie but can be gotten for a pretty good price when available.
They are adjustable up to 6 bands with this unit.
The only thing we don´t like about this unit is the Latency. When you listen real time to
your TX Monitor there is a slight delay through this unit.

On the higher end of the food chain are the Analog Tube Multi-Band Compressors.
There are only 2, the TubeTech SMC-2BM, and the Drawmer S3.
Now get ready for the price, are you sitting down? Well you better because the
TubeTech is about $6000.00 and the Drawmer about $5000.00.
These were just a little out of budget for us to use on amateur radio.

We had to have an Analog unit, and it had to have tubes.
While searching on the web one day trying to find an alternative, we came across
the Drawmer Three-Sum Multi-Band Interface. This was the answer!!!
It was totally Analog, and you used outboard compressors.
If we could find one of these units then we could use any tube compressor we wanted for
the compression function. As fortune would have it, the Drawmer was found and purchased.

We have had the Drawmer Three-Sum Multi-Band Interface in the rack since July of 2011.
Two of the Bellari RP-583 Tube Compressors are being used with the Drawmer.
This Analog combination took the place of the digital TC Electronic Triple-C that we
have been using for the past 5 years. Make no mistake, the Triple-C is a fine piece of
equipment and performed exquisitely in its muti-band functions.
We were just looking for something to bring us to that next level.

How do you hook it up??

We have the Drawmer located as the last compressor in the rack.
It is directly after the Behringer EX3200. The signal leaves the EX3200 and
enters the Drawmer where it is split into 3 bands, Low, Med, and High.
Each one of these bands goes to a separate channel on the 2ea RP583 compressors.
The signals then leave the compressors and are fed back into the Drawmer where
they are Summed (re-combined) into one mix again. The signal goes thru a
Peak Limiter in the Drawmer then proceeds to the MX882 mixer.

Here is a visual of how it is connected in the Studio-X Rack,
click on it to make it big:

Studio-X Voodoo Audio Rack!

What are the settings??

We knew that question was coming! Unfortunately, The settings for you
are not going to be any where close to the settings we have.
Even if you had the same exact equipment piece for piece as what is in Studio "X",
the settings would be completely different. This is due to the different voice
and equipment characteristics. Analog Audio is not an exact measure and
no 2 pieces of equipment are the same, so no 2 pieces will adjust the same.
You have to learn your equipment, and know how it reacts to the mix under certain adjustments.
In other words, you have to "train" your ears to listen and adjust accordingly.
You cannot just look at a display or meters and expect to be able to fine-tune this animal.
We have been playing with it for 3 months now and are still learning its nuances.
This is one of the reasons why we stated earlier that the learning curve is a
bit steep and takes a while to develop an ear for this type of processing.
We will not go into the basics such as proper Gain Structure and
other topics as this is already well documented.

Here are a few articles that explain all about compression.
They are penned by one of my favorite authors, Michael Cooper.

The Big Squeeze

Let´s Split

Basically, the first thing you need to do is set the Crossover Points
on the Low and High Split Frequencies. Mine wound up being set to
around 160cps on the Low and 2.5kc on the High. Our Input Gain and
Output Gains are set to around –3dB. The Peak Limiter is set to around +2dB.
The Gain reduction lights just occasionally show –1dB gain reduction with
a –3dB on overshoot peaks.

The next thing is to set the compressors.
The Low Band Compressor is set up to smooth the lows.
This is accomplished by using a slow Attack of about 50ms,
a very slow Release of about 2 seconds, a Ratio of about 4:1,
and by tuning the Threshold to achieve about 2dB – 3dB of Gain Reduction.
The Make up gain is set to achieve a tonal Mix balance along with the Mids and Highs.

The Mid Band Compressor is set up to give the Mids some density.
This is accomplished by using a moderate Attack of about 20ms to 30ms,
a Release of about 1/2 second, a Ratio of about 4:1 to 5:1,
and by tuning the Threshold to achieve about 3dB – 5dB of Gain Reduction.
The Make Up Gain is set to achieve a tonal Mix balance along with the Lows and Highs.

The High Band is set up for de-essing and sibilance.
This is accomplished by using a very fast Attack of about .5ms,
a very fast Release of about .1 second, a Ratio of about 4:1 to 5:1, a
nd by tuning the Threshold to achieve about 6dB of Gain Reduction on peaks while
talking normally, and about 20dB on a hard "ssss".
The Make up gain is set to achieve a tonal Mix balance along with the Lows and Mids.

Now that this setting is close, you have to listen to the
TX Monitor (Off Air Monitor) and adjust for effect.
While listening, tweak the Low Split Frequency control back and forth to
find the best sounding setting. Now tweak the Threshold settings on the
Low and Mid compressors along with the Make Up gains to get the best balanced sound.
Do the same thing with the High Split Frequency control and the
Mid and High Thresholds and Make Up Gains. Readjust the Lows,
then back to the Highs. The closer you get, the more of a
difference a small adjustment will make. When you think your close enough,
now you can start to fine tune the Ratio, Attack and Release timings on the different compressors.

As you can see, this is a very touchy operation.
You must be able to hear what you are doing.
We say to listen the the TX Monitor or an Off Air Monitor while you adjust
as that is actually your "Final Mix" and you are tuning for that to sound the best.

How does it Perform?

Fabulous!! Terrific!! Phenomenal!! Awesomely!! Brilliantly!!
These are just some of the words that jump to mind. This unit is incredible.
It is exactly what we were looking for.

The Drawmer Three-Sum is built very well; there was no skimping on
the inside as it was well designed both structurally and electrically.
We have only had one problem with it. There was a substantial amount of
RFI getting into the Peak Limiter Circuit when it was engaged and
operating on 40 meters. None of the normal RFI abatement procedures would
put a dent in it. This could have been just site specific to this location as
Drawmer said they have never had any other complaints.
After talking to the engineer, we decided to put in some extra RF Bypassing in
the Peak Limiter Circuit and that fixed the problem permanently.

I must say that it was a pure pleasure to work with the Drawmer Tech Department.
I have never had such a pleasurable experience with a major company before.
These guys know their stuff and are not scared to help you out.
Thanks Drawmer!!

We spent allot of time on the air comparing the Drawmer 3-Sum to the Triple-C.
This was mostly done on 80 meters with Eddie, W5NVI making the
recordings with his TS-950VMSDX. There are a few of me on an
off air receiver, and one recording on 20 meters from NA1A.
Here are some of the Sound Bites:

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