Behringer - DC9 Dynamics Compressor

lubeto · Post by **lubeto** » 21 Oct 2008, 01:23

Behringer DC9

PCB photos
Top Layer

Bottom Layer

Circuitry close up

It is using surface mount BC846 transistors, CoolAudio V13700 absolutelly identical to LM13700.

I will post the schematic tomorow.

analogguru · Post by **analogguru** » 21 Oct 2008, 05:19

Wait... before you post it..... let me guess:
Is it a DynaComp-clone or is it (nearly) identical to the Ibanez CP9 schematic

which can be found here:
https://www.freestompboxes.org/viewtopic.php?f=1&t=2671
or a mixture of both ?

analogguru

lubeto · Post by **lubeto** » 21 Oct 2008, 10:00

It is almost identical to Dynacom.

Well this is the schematic

Behringer_DC9.pdf: (95.01 KiB) Downloaded 625 times

Looking at the ic there is some room for upgrades. There are nice FET buffers available. The differential inputs of the opamp could be DC clamped which should reduce the noise a lot.

It is going to be a nice weekend project.

Cheers everybody

analogguru · Post by **analogguru** » 21 Oct 2008, 12:41

Sadly the schematic is a bit incomplete. At least R7, R12, C9 are missing.

analogguru

BJF · Post by **BJF** » 21 Oct 2008, 13:05

Hi,

Right the LM13700 is a better OTA than CA3080, but yes there will be noise and MXR combatted that via a pre emphasis at the input and deemphasis at output, but curves do not align and there is then a loss of treble yet wideband noise.Also maximum input before distortion is something like 20mV's.....oh well

Indeed the schematic looks like its missing some components, mainly the pre emphasis and DC -bias

Have fun
BJ

lubeto · Post by **lubeto** » 22 Oct 2008, 00:43

The corrected schematic is here.

Behringer_DC9.pdf: (43.68 KiB) Downloaded 600 times

-Cheers-

lubeto · Post by **lubeto** » 22 Oct 2008, 01:18

BJF wrote:Hi,

Right the LM13700 is a better OTA than CA3080, but yes there will be noise and MXR combatted that via a pre emphasis at the input and deemphasis at output, but curves do not align and there is then a loss of treble yet wideband noise.Also maximum input before distortion is something like 20mV's.....oh well

Indeed the schematic looks like its missing some components, mainly the pre emphasis and DC -bias

Have fun
BJ

If we bias the linearizing diodes on through the positive power supply voltage we scan extend the max input swing before distortion. We can open the a bit the high pass filters before the OTA. This way may be we can get thicker sound without an increase in the noise level. We can also buffer the output of the amp.
Am I right?

toneman · Post by **toneman** » 22 Oct 2008, 04:24

so what's the other half of the 13700 doing?

BJF · Post by **BJF** » 22 Oct 2008, 11:17

Hi,

The other OTA can just hang an do nothing, but it could be a good idea to hook up inputs of the unsued OTA to supply midpoint.

Yes you can increase input range by utilizing the linearization diodes. You'll have to try that, I have not done that personally.
There would be an example of that in the datasheet of LM13600/LM13700

To increase inputvoltage handling put a resistor in series with C5- and that's the recommended way from National Semiconductors. The input is controlled by current and a resistor here makes the input voltage controlled as the current develops a voltage over the resistor. Further read on that can be found in IC OP Amp Cookbook by Jung.

On the filter sections further thoughts here
viewtopic.php?f=7&p=37338#p37338

Have fun
BJ

ShortScaleMike · Post by **ShortScaleMike** » 22 Oct 2008, 11:47

If it's a clone of the Dyna Comp it doesn't do a very good job. I made this video comparing them, the Dyna Comp sounded a lot better.

The Behringer is a lot more toppy and less musical.

wildschwein · Post by **wildschwein** » 23 Oct 2008, 11:55

ShortScaleMike wrote:If it's a clone of the Dyna Comp it doesn't do a very good job. I made this video comparing them, the Dyna Comp sounded a lot better.

The Behringer is a lot more toppy and less musical.

Yeah I agree; it has quite a large bass cut. I stuffed mine up trying to tamper with it - but I don't really miss it since I got an even cheaper Daphon E10CS as a replacement which has a much fuller and a more natural sounding frequency response. The DC9 has a nice housing though which is a perfect size for a Distortion + clone.

snyder80 · Post by **snyder80** » 22 Nov 2008, 22:15

Hello there!

Well i got the dc9 as a birthday present some weeks ago.
i compared the posted pics above with my pcb and there i maybe found an assembly "mistake" on mine:

R 11 (false noted as R47 in posted schematic ) seems to be a capacitor in smd-type on mine, although the pcbprint says 150k !!!

I havent got my measurement tools by my side, but it isnt the typical "black with some numbercode".INstead its a white and ceramic-type square-piece like the other caps on my pcb.No numbers.

Can maybe wildschwein verify a faulty factory-assembling ?! Or wouldnt the pedal work without the 150k on IC-pin5 at all ???

Greetings,

snyder80

fws · Post by **fws** » 15 Feb 2011, 00:35

Is that trim for signal mix? Ive got one, but its loosing output if I turn compression down.

bassetrox · Post by **bassetrox** » 21 Sep 2014, 17:31

Hi all,

Sorry for bumping a long dead thread.

I've been looking at the characteristics of the DC9 recently, frequency response etc.

Here's a compression performance graph:

It takes quite a lot of signal level to acheive compression here - I don't think the pedal is quite sensitive enough.

And here's a graph of frequency response in and out of compression.

It does tend to suggest that people who were hearing a perceived bass cut with this pedal were perhaps hearing it when it wasn't compressing.To me, in ShortScaleMike's great comparison video, the MXR appears compress the signal significantly more.

Hopefully you guys will find the info interesting, if not useful!

More info on:
http://ampworks.co.uk/experiments/behri ... ervations/

LesPaulMan · Post by **LesPaulMan** » 25 Sep 2014, 06:56

snyder80 wrote:Hello there!

Well i got the dc9 as a birthday present some weeks ago.
i compared the posted pics above with my pcb and there i maybe found an assembly "mistake" on mine:

R 11 (false noted as R47 in posted schematic ) seems to be a capacitor in smd-type on mine, although the pcbprint says 150k !!!

I havent got my measurement tools by my side, but it isnt the typical "black with some numbercode".INstead its a white and ceramic-type square-piece like the other caps on my pcb.No numbers.

Can maybe wildschwein verify a faulty factory-assembling ?! Or wouldnt the pedal work without the 150k on IC-pin5 at all ???

Greetings,

snyder80

Any chance the resistor is placed upside down? They have white ceramic undersides. Sometimes happens in the assembly process, but it wouldnt affect functionality.

rsasgtr · Post by **rsasgtr** » 11 Apr 2023, 16:13

This post is probably a bit late, but I think it might be worth for people who still own this compressor.
I compared the schematic with Dyna Comp's and noticed that the most significant differences were the 47k R11 resistor (incorrectly marked in the attached pdf as 150k R47) vs 150k, and 47n C5 vs 10n. Actually, on my version of the PCB, the spots were marked as 150k and 10n, but the actual components were different.

So I replaced R11 and C5 with the Dyna Comp values.
Replacing R11 brought back the low-end, and also enabled higher compression.
Replacing C5 cut the low-end back again, but not as drastically, and the compression level stayed high.

I don't have a Dyna Comp to compare against, so I'm attaching the sound samples.
The setup is a Strat bridge pickup into the DC9, then a DI box and an interface. No amp sims.
DC9 compression is set to maximum, and the volumes were matched after the recording.

Behringer - DC9 Dynamics Compressor [schematic]