[nebulax]

Just found this profound statement on a data sheet for a dbx 166xs
compressor. I don't know offhand who should get credit for 'inventing
the
compressor', but they existed way before the dbx company was even
founded, right?

-Neb

[Adrian Tuddenham[_2_]]

nebulax wrote:

Just found this profound statement on a data sheet for a dbx 166xs
compressor. I don't know offhand who should get credit for 'inventing
the
compressor', but they existed way before the dbx company was even
founded, right?

I believe A.D. Blumlein was using an experimantal system of automatic
volume control on wax recorders in the late 1920s. The BBC were
certainly using very effective compressors/limiters on their
transmitters and recording lathes in the 1940s.

How old is the dbx company?


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

[PenaL]

Adrian Tuddenham wrote:
nebulax wrote:

Just found this profound statement on a data sheet for a dbx 166xs
compressor. I don't know offhand who should get credit for 'inventing
the
compressor', but they existed way before the dbx company was even
founded, right?

I believe A.D. Blumlein was using an experimantal system of automatic
volume control on wax recorders in the late 1920s. The BBC were
certainly using very effective compressors/limiters on their
transmitters and recording lathes in the 1940s.

How old is the dbx company?



....was founded in 1971.

http://en.wikipedia.org/wiki/Dbx,_Inc.

-Pentti

[Scott Dorsey]

nebulax wrote:
Just found this profound statement on a data sheet for a dbx 166xs
compressor. I don't know offhand who should get credit for 'inventing
the
compressor', but they existed way before the dbx company was even
founded, right?

Yeah, BUT David Blackmer at dbx did come up with the standard VCA design
that everyone today uses. It was an absolute and total revolution in
compressor design.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Trevor]

"Scott Dorsey" wrote in message
...
nebulax wrote:
Just found this profound statement on a data sheet for a dbx 166xs
compressor. I don't know offhand who should get credit for 'inventing
the
compressor', but they existed way before the dbx company was even
founded, right?

Yeah, BUT David Blackmer at dbx did come up with the standard VCA design
that everyone today uses. It was an absolute and total revolution in
compressor design.

Well not "everyone" since many people think anything "retro" must be better.

Trevor.

[nebulax]

On Jan 17, 4:18*pm, (Scott Dorsey) wrote:
nebulax wrote:
Just found this profound statement on a data sheet for a dbx 166xs
compressor. I don't know offhand who should get credit for 'inventing
the
compressor', but they existed way before the dbx company was even
founded, right?

Yeah, BUT David Blackmer at dbx did come up with the standard VCA design
that everyone today uses. *It was an absolute and total revolution in
compressor design.
--scott



Well then, I guess it would be more accurate to say "dbx knows VCA
compressors...", tho' that would be somewhat less impressive sounding.
Now if they said "We also traveled back into history with our magical
time machine, and came up with the original designs for the Fairchild
660 limiter", then I'd be impressed!

-Neb

-Neb

[MG[_4_]]

"nebulax" wrote in message
...
On Jan 17, 4:18 pm, (Scott Dorsey) wrote:
nebulax wrote:
Just found this profound statement on a data sheet for a dbx 166xs
compressor. I don't know offhand who should get credit for 'inventing
the
compressor', but they existed way before the dbx company was even
founded, right?

Yeah, BUT David Blackmer at dbx did come up with the standard VCA design
that everyone today uses. It was an absolute and total revolution in
compressor design.
--scott



Well then, I guess it would be more accurate to say "dbx knows VCA
compressors...", tho' that would be somewhat less impressive sounding.
Now if they said "We also traveled back into history with our magical
time machine, and came up with the original designs for the Fairchild
660 limiter", then I'd be impressed!

-Neb

-Neb

The folks at CBS Labs who developed the Audimax will be surprised to hear
this.

[Scott Dorsey]

MG wrote:
"nebulax" wrote in message
Scott wrote:

Yeah, BUT David Blackmer at dbx did come up with the standard VCA design
that everyone today uses. It was an absolute and total revolution in
compressor design.

Well then, I guess it would be more accurate to say "dbx knows VCA
compressors...", tho' that would be somewhat less impressive sounding.
Now if they said "We also traveled back into history with our magical
time machine, and came up with the original designs for the Fairchild
660 limiter", then I'd be impressed!

The folks at CBS Labs who developed the Audimax will be surprised to hear
this.

I don't recall the original tube Audimax, but the solid state 400-series
used a bipolar transistor with the bias point changed by a control
voltage. Linearity was orders of magnitude poorer than you could get
with the Blackmer VCA.

The Blackmer circuit could get you distortion levels that were impossible
to obtain without an optical LCR, but with a response time hundreds of
times faster than the Lumiten or Vactrol. On top of that, it gave you
much wider usable gain range.

It really was a total revolution, it's really what made VCA automation
and companding for noise reduction possible.

Mind you, the control circuit on the Audimax which locked the gain on
silent passages was a revolution in itself, and the same design is
showing up in a lot of dsp broadcast compressors today....
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Robert Orban[_2_]]

In article , says...


The Blackmer circuit could get you distortion levels that were impossible
to obtain without an optical LCR, but with a response time hundreds of
times faster than the Lumiten or Vactrol. On top of that, it gave you
much wider usable gain range.

It really was a total revolution, it's really what made VCA automation
and companding for noise reduction possible.


Properly linearized FET compressors can be very clean too. IIRC, the harmonic
distortion caused by the FET attenuator in an Optimod 8000 was in the order
of 0.025%, which was achieved by limiting the audio level across the FET to
about 20 mv. It was followed by a low-noise amplifier.

The main problem with FET gain control elements, which was solved in the
Blackmer VCA, is that their resistance vs. control voltage curve is quite
unpredictable, making them suitable only for feedback compressors. In the
8000, we addressed the L/R stereo tracking problem by using a monolithic IC
with four FETs. These tended to match quite well.

A FET attenuator is pure "class A" in the sense that it has no crossover
distortion, which is actually a big advantage. This was a problem in the
original Blackmer designs.

Bob Orban

[MarkK]

Properly linearized FET compressors can be very clean too. IIRC, the
harmonic
distortion caused by the FET attenuator in an Optimod 8000 was in the
order
of 0.025%, which was achieved by limiting the audio level across the FET
to
about 20 mv. It was followed by a low-noise amplifier.

.

Bob Orban


Bob,
also besides keeping the audio level on the drain low, as I'm sure you
already know, the trick of feeding 1/2 of the audio into the gate, greatly
reduces the distortion as well..

http://www.eecg.toronto.edu/~kphang/...martin_AGC.pdf



Mark

[Robert Orban[_2_]]

In article , says...

Properly linearized FET compressors can be very clean too. IIRC, the
harmonic
distortion caused by the FET attenuator in an Optimod 8000 was in the
order
of 0.025%, which was achieved by limiting the audio level across the FET
to
about 20 mv. It was followed by a low-noise amplifier.

.

Bob Orban


Bob,
also besides keeping the audio level on the drain low, as I'm sure you
already know, the trick of feeding 1/2 of the audio into the gate, greatly
reduces the distortion as well..

http://www.eecg.toronto.edu/~kphang/...martin_AGC.pdf

Indeed. We used this technique in the design of the 8000. I don't know who
invented it, but it was already known ca. 1968.

Bob Orban