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Dbx 128 Mods
Old 18th March 2013
  #1
Lives for gear
 

Dbx 128 Mods

just a few pics of a dbx128 I recapped & modded





Im running LME49710NA opamps on the singles and ne5532s on the duals pretty clean beefed up the psu caps from 470uf to 1000uf as well.
Old 25th March 2013
  #2
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I noticed a low level hum in the unit and decided to keep modding it




pulled the transformer out and made my own diy wall wart supply now its very quiet with a self noise of -108db at -6db on the meters
Old 10th June 2013
  #3
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Where did you used the LME Opamps? Did you bypassed them?

How and which Powersupply did you used?

I have a Problem with my DBX, one of these boards is defective. One of the boards with the red caps next to the transformer. I cross changed them and so i know that one of them is defective. But i dont know what is defective. There is no Signal coming from board. Any Ideas? I thought that one of the transistors or maybe the tba331 could be defective. Any tip how i could find it out?
Old 14th June 2013
  #4
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id check the tantalum caps first. I had to change every one in mine. The opamp I picked is pretty mild and unity stable so it didn't need bypassing. I also pulled the noise reduction cards from mine which made it a dbx 118 in all reality.
Old 14th June 2013
  #5
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mine had some issues. the tantalumns were fu**ed up. changed them with panasonic fc series. Recapped the PSU. Then there was an defective Transistor Array on one of the cards. Now it works. Only problem is when i switch between linear and above threshold... the linear sounds **** on the first hit of the basedrum... dont know if this is normal or if there is something ****ed up. I changed 2 of the opamps for ne5532. I was thinking for swapping them with opa2134 which i like soundwise. LME49710NA they sound very clean and accurate, i like them but maybe not the right choice for a coloring box...

From what i can say after a few tries, this box makes a fatter sound. Nice for Drums and also for Bass and Musical Material. The good thing is i can switch to -10dbv on my interface so i can sent the right signal to it....

How do you use it?

Thanks for your help.
Old 15th June 2013
  #6
Lives for gear
 

parallel processing on the drum bus and on the bass, but most of the time I'm using the dbx 163x for the bass.
Old 7th January 2019
  #7
Here for the gear
 

This is my modded DBX 128 project. It has true bypass, 1/4 jacks, input and output gain control, attack and release control, an upgraded power supply, and a side chain input.

This is my modded DBX 128 project. It has true bypass, 1/4 jacks, input and output gain control, attack and release control, an upgraded power supply, and a side chain input.
Attached Thumbnails
Dbx 128 Mods-20190106_161732.jpg   Dbx 128 Mods-20190106_161759.jpg   Dbx 128 Mods-20190106_161717.jpg   Dbx 128 Mods-20190106_161759.jpg   Dbx 128 Mods-20190106_161717.jpg  

Dbx 128 Mods-20190106_161732.jpg  

Last edited by Synth Guru; 13th January 2019 at 09:06 PM.. Reason: Same thread
Old 8th January 2020 | Show parent
  #8
Here for the gear
 

This looks amazing! I have a couple 128's and I love them, but they're a bit noisy (one more than the other). I'd love to have this kind of functionality

Quote:
Originally Posted by ColoradoSynthDoc View Post
This is my modded DBX 128 project. It has true bypass, 1/4 jacks, input and output gain control, attack and release control, an upgraded power supply, and a side chain input.

This is my modded DBX 128 project. It has true bypass, 1/4 jacks, input and output gain control, attack and release control, an upgraded power supply, and a side chain input.
Old 11th July 2020
  #9
Here for the gear
 

Troubleshoot help

Hey guys!

I have a non working unit that I'm trying to get up and running. I've seen the issue described a few times on here but no one has mentioned the fix.

Here's what is going on: It powers on, will let the bypassed signal but won't do anything else. No signal comes out of the unit if any function is engaged. The threshold lights (above and below) won't light. I guess there might be trouble in the power section.

Got the unit a few years ago on eBay as a broken box. It used to have the yellow below threshold light on and you could not get it to go above the threshold. I don't remember if it passed any signal (I believe it did but the signal was unprocessed).

Now neither below nor above will light up. It will only pass signal in bypass.

Nothing looks blown up inside. I do not have a scope, unfortunately.


Anyone have any ideas?
Old 12th July 2020
  #10
Here for the gear
 

FIXED

Almost as soon as I posted this, I found the problem and my DBX 128 which was non functioning is now WORKING.

Problem was NOT in the power section as I had suspected. I tried pulling out the VCA and RMS cards one at a time. When I pulled the RMS card, the Red "Above Threshold" LED lit up.

After poking around with a multimeter on the RMS card, I found C3 was shot. So those who were mentioning issues probably resulting from a tantalum cap were spot on.

I swapped a working one from one of the NR cards and BOOM. DBX 128 lives again. Guess I didn't need to buy those CA3046 replacements.

(I never post on these forums when I get stuff to work so I figured it's time to start giving back.)

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