dbx 160vu clone

[onlymeeee]

Has anybody thought about DIYing the dbx 160vu.
It's my favourite compressor for kicks and basses and wonder how hard it'd be to DIY one.

It uses a dbx 202 right?

Any thoughts?

 

[shabtek]

how does this differ from current production 160 compressors?


pico comp is said to be as good as dbx comps(?)
and it is legit, and supported and DIY and all the ward work has been done for you.

 

[drpat]

...

 

[SSLtech]

[quote author="drpat"]...the 160s or sl. If so, please disregard all of the above, as I've never used those units...[/quote]

You're not missing much, Pat!

I despise the fact that dbx used the model number "160" to refer to so many different and extremely differently-charactered units. -Even the NUMBER of front panel controls is incomparable between the 160S/160SL and the 160X for example. -With the later S and SL versions having INTERNAL switches for program dependent release, which most people don't even KNOW about. -They ended up putting so many controls on the blessed thing that they didn't even have enough front panel space to put them all on there!

I once got a failure report from Eddie Kramer about a 160X which was distorting. -It turned out that he didn't know how to use it, and didn't know that "peak stop" on the 160 is a waveform distortion function. -Nor did he know which way to turn the control, as it happens...

Keith

 

[Electrobumps]

I completely agree with SSL Tech I was fortunate to work in studios with the dBX 160vu's for several years.

I love them on Bass guitars. When I'm working on a Neve and don't have an SSL channel Compressor free they great on kicks too.

I've been told by a tech they use a similar VCA to an SSL E/G channel which would make sense. They also told me that the way the VCA distorts is also the reason they sound great on bass and drums.

When I went freelance and went into to other studios with the new versions of the 160, like the xt and SL just didn't cut the mustard.

The 160Vu is so easy to use and grabs hold of your audio just the way you want it too. I know its always going to be a longer job to get my bass to sit in the mix without one the 160vu

If I walk in to a studio with these new models I just think what a waste of money.

I've tried so many times to get the new versions to work in a mix, I just thought it would be impossible for dBX to get the new versions so wrong, but they did. I don't even bother plugging them up any more.

The 160vu is an expensive beast to buy. At the moment having one of these isn't justifiable in costs for me, as a lot of places I work have them. However if the PCB's where out there for these I wouldn't think twice about building one.

They look pretty simple inside, so if someone is clever enough to reverse Engineer this. PLEASE DO IT.

 

[onlymeeee]

I agree, none of the current dbxs are even close to the 160vu.
Would be good to get a DIY one going. Any volunteers?!

I have found the schematic here
ftp://ftp.dbxpro.com/pub/PDFs/discontinued/Schematics/160-161-162 Schematic.pdf

 

[tomelectro]

The 160VUs used the original "Black Can" 202 VCAs, which had a -6mv/dB control voltage constant. All subsequent DBX 202 models (202C and up) used a 50mV/dB constant. So unless you can source some original 202s (hens teeth) or find some THAT corp 202Rs or 2002Rs (later replacements for the original 202, but also discontinued I believe), some minor circuit re-engineering will be required. See the THAT corp design note #127 "Upgrading Modular VCAs" for some excellent reading.

The 160VU is a great sounding compressor! Would make a nice clone project, but I suspect the 202 is a significant part of it's sound.

Another challenge would be the RMS detector potted modules!

 

[CJ]

Hi Res-backside:
http://vacuumbr.ipower.com//The_Lab/DBX/dbx_board2.jpg

 

[matthias]

there's no 202 vca in the dbx 160 (vu)

but the 200 vca module and the 208 or 209 rms module

you could rip exactly these modules from a dbx 119
or clone the 208 module (easy job) and use "that 218x" for the vca.
they have a constant of 6,1db/V . that's very close.
I also think that most of the 160-sound comes from the rms detector and not from the vca....

considering a clone of the 160 you would also have to modify the metering part. dbx used a special meter that centers in the middle...



get some more info about the 160 circuit here: http://www.uaudio.com/webzine/2008/march/index2.html

 

[juniorhifikit]

While searching for some diy DBX info, I came across this thread - wow.  Has anyone made a 208 detector from these drawings?  I was originally looking for info on how to change DBX 903's (160x on a card) from over easy to "normal" knee.  Now I'm thinking about the possibility of making a few 160vu's on cards for my 900 rack.

Sorry to dig up old crud.  I was especially impressed with CJ's diy excavation on the potted detector circuit!

 

[abbey road d enfer]

I don't really agree with the notion that the specific sound of the 160 lies in the potted VCA and RMS detector. I'm not saying either they don't have their own sonic signature, but there are essential differences in the side chain that are surely accountable for most of the differences.
In the 160VU, the RMS detector charges a single cap, where in most other incarnations of the 160 (and other compressors), the RMS is loaded with an active variable Time Constant cap, in order to present a large value to small level changes, and a smaller value to large level changes. One of the criticisms to the first 160 was that the attack time wasn't fast enough for some instruments (in particular kick and snare), although it has some kind of accelerating circuit in the side-chain (two diodes and a cap). This also gave it a soft knee. The dbx engineers worked out this variable TC detection in response to the criticism. Then they had to implement the soft knee in a slightly different way. This and a few other differences may account for a large part of the sound difference.
The control voltage is not an issue, since it is obtained with a voltage divider in the 50mV/dB and 100mV/dB types. The control voltage is scaled accordingly.
I had the opportunity to make a comparison between two issues of a broadcast mixer, one with a very early 202, and one with a 202XT. I must say there was not much difference, except for the higher noise of the latter, due to the fact that the designer had chosen too high resistor values around the VCA, which was ok with the early 202, with its FET input, and not right for the modern 202, with its 8 paralleled bipolar devices.

 

[iangomes]

thread revival, I'm messing around with athe dbx schematic, but I can't find any info (schematic?) on the rms208.... Does anyone have a source?
Thanks
Ian

 

[QUEEF BAG]

langomes-

tryin' to upload some info
it might take a time or two

 

[iangomes]

wow! I didn't expect to actually get something! thanks queefbag!! (that sounds like an insult, haha)
Thank you so so much!  ;D ;D

 

[Tekay]

Look around for old DBX154 noisereductions units, I bought one for a couple of dollars at ebay and it contained EIGHT 200VCA's and EIGHT 208RMA moduls. 

 

[ChrioN]

http://cgi.ebay.com/DBX-4-channel-154-Noise-Reduction_W0QQitemZ250516905206QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3a53f89cf6

 

[Tekay]

There should be four of each in that unit! The one I bought was a double unit.

 

[matthias]

you can also find the 200 (vca) and 208 (rms) modules in the dbx 117 and dbx 119

I bought a 117 and a 119 some time ago, and there are modules that are potted and some, that are not...
I had 4 potted modules and 3 of them were not working
the unpotted modules from the 119 and my dbx 160 were all ok.

I did some research on the vca module....  here's a schematic/layout

dbx model200 vca module.pdf

btw: does anyone have a good readable schematic of the 160 ?

 

[Biasrocks]

btw: does anyone have a good readable schematic of the 160 ?

DBX has services manuals, calibration procedures and schematics for many of the older dbx products on their website.

http://www.dbxpro.com/product_downloads/Schematics/160%20Schematic.pdf

http://www.dbxpro.com/vintage_download.php?product=160

Mark

 

[Morning_Star]

Anyone make any headway on a pcb layout for this project?