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Modifying a DBX 163X
Old 17th November 2009
  #1
Modifying a DBX 163X

I found a couple old post by Jim Williams on how he modifies the dbx 163X. Some stuff is fairly simple, like replacing all the electrolytic caps, removing the HF roll-offs, replacing op amps and the VCA, and replacing the main caps.

However, there are some things that are over my head because I only have a very basic understanding of electronics.

For example:
"The power supply is rebuilt with large caps and a polyprop film bypass. Audio cap gets a polyprop bypass"

I'm not sure what caps are part of the power supply because it doesn't have it's own circuit. I understand what a capacitor bypass is, but in an audio circuit is it important to use several capacitors in parallel?

"The input impedance is lowered to 100k ohms."

How is this done?

"Phase compensation added."

Don't know about this either.

Also, for replacement electrolytic I was going to order Nichicon VZ series capacitors...good choice? I ordered some Elna for the audio caps but they were too big so I need to exchange them at digikey.
Old 25th December 2011
  #2
Gear Maniac
 
Doctor Rockter's Avatar
 
🎧 10 years
Yeah, would be cool if Jim could give us some info on this or even inform us about the $$ he charges for doing these mods..

Interested as well !!
Old 25th December 2011
  #3
Lives for gear
 
memphisindie's Avatar
 
🎧 10 years
Quote:
Originally Posted by Sean Sullivan ➑️
I found a couple old post by Jim Williams on how he modifies the dbx 163X. Some stuff is fairly simple, like replacing all the electrolytic caps, removing the HF roll-offs, replacing op amps and the VCA, and replacing the main caps.

However, there are some things that are over my head because I only have a very basic understanding of electronics.

For example:
"The power supply is rebuilt with large caps and a polyprop film bypass. Audio cap gets a polyprop bypass"

I'm not sure what caps are part of the power supply because it doesn't have it's own circuit. I understand what a capacitor bypass is, but in an audio circuit is it important to use several capacitors in parallel?

"The input impedance is lowered to 100k ohms."

How is this done?

"Phase compensation added."

Don't know about this either.

Also, for replacement electrolytic I was going to order Nichicon VZ series capacitors...good choice? I ordered some Elna for the audio caps but they were too big so I need to exchange them at digikey.
β€’ UTSF β€’
It's all in there.
I did it. You need a schematic to show you the circuits, the power supply is separate but not on a separate board.
I was easy once I got the right schematic. You need to read about electronics a bit before you start doing your own mods to components, but, once you do it comes easy to mod. "Designing" new stuff takes a lot more reading and modding. It's fun, you can do it.
Old 26th December 2011 | Show parent
  #4
Lives for gear
 
🎧 15 years
Just playing devil's advocate...

Why do you want to change it? Is it malfunctioning? It may be fun, educational, and make the sound more "hi-fi", but one of the things people like about this compressor is the midrangey distorted sound. I have three of them that get used on almost every mix, and their midrange "knock" is what I like about them. If they were clean and transparent, they'd be useless to me.

What you hide in a mix is just as important as what you reveal.

YMMV
Old 26th December 2011 | Show parent
  #5
Lives for gear
 
memphisindie's Avatar
 
🎧 10 years
Quote:
Originally Posted by juniorhifikit ➑️
Just playing devil's advocate...

Why do you want to change it? Is it malfunctioning? It may be fun, educational, and make the sound more "hi-fi", but one of the things people like about this compressor is the midrangey distorted sound. I have three of them that get used on almost every mix, and their midrange "knock" is what I like about them. If they were clean and transparent, they'd be useless to me.

What you hide in a mix is just as important as what you reveal.

YMMV
It will still have that midrange, it just gets smoother extended but not hyped top end and tighter low end.
Old 26th December 2011
  #6
Gear Guru
More distortion, please?

Add a couple of diodes across the audio path. That works in my fuzz tone.
Old 27th December 2011 | Show parent
  #7
Lives for gear
 
mjrippe's Avatar
 
🎧 10 years
Quote:
Originally Posted by Jim Williams ➑️
More distortion, please?

Add a couple of diodes across the audio path. That works in my fuzz tone.
What is that supposed to mean?
Old 28th December 2011
  #8
Lives for gear
 
memphisindie's Avatar
 
🎧 10 years
You new?
Jim (who was here before records of time) is a clean freak. He likee the clean audio and he is correct, as usual, diodes across the path will make the fuzzzzz noise.
It's Jim humor. get to know him, you'll love him, everyone does.
Old 28th December 2011 | Show parent
  #9
Lives for gear
 
Ike Zimbel's Avatar
 
🎧 10 years
Quote:
Quote:
Quote:
Originally Posted by juniorhifikit View Post
Just playing devil's advocate...

Why do you want to change it? Is it malfunctioning? It may be fun, educational, and make the sound more "hi-fi", but one of the things people like about this compressor is the midrangey distorted sound. I have three of them that get used on almost every mix, and their midrange "knock" is what I like about them. If they were clean and transparent, they'd be useless to me.

What you hide in a mix is just as important as what you reveal.

YMMV
Quote:
"It will still have that midrange, it just gets smoother extended but not hyped top end and tighter low end."
And less noise. I have upgraded several 160 VU's and I often see a lot of reluctance to have the work done because people "like what it does". Well, when it's done, it still compresses like a 160, but it's cleaner, more open, better transient response and less noisy. They sound killer on drums, but work well on other things as well.
Old 28th December 2011
  #10
Lives for gear
 
🎧 10 years
Look in tape op message board. You can google dbx 163x mods and It's like the second thing that comes up. There is 7 pages worth of stuff. I just swapped out the 1000uf cap, swapped the op amp for the one suggested in that thread, and cut out one resistor for the op amp swamp and It sounds incredible after that. They said that is the important stuff but also list like 30 cap changes just a bunch of info.

Normally the first thing I do when I want to mod something is do a google search there are a few other forums with info on modding and just a wealth of information on the internet.
Old 29th December 2011 | Show parent
  #11
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mjrippe's Avatar
 
🎧 10 years
Quote:
Originally Posted by memphisindie ➑️
You new?
Jim (who was here before records of time) is a clean freak. He likee the clean audio and he is correct, as usual, diodes across the path will make the fuzzzzz noise.
It's Jim humor. get to know him, you'll love him, everyone does.
Yes, I know about Jim. Not everyone agrees with him, but all respect him. My point was that nobody was asking about adding distortion so his comment was out of left field and not helpful to the OP.
Old 29th December 2011 | Show parent
  #12
Gear Guru
Quote:
Originally Posted by juniorhifikit ➑️
one of the things people like about this compressor is the midrangey distorted sound.
Sometimes I feel like the comic that needs to explain the joke, I guess I need to work on that.

Love/hate/respect/loath, it's all the same to me. As long as you're entertained...
Old 30th December 2011 | Show parent
  #13
Lives for gear
 
memphisindie's Avatar
 
🎧 10 years
Quote:
Originally Posted by Jim Williams ➑️
Sometimes I feel like the comic that needs to explain the joke, I guess I need to work on that.

Love/hate/respect/loath, it's all the same to me. As long as you're entertained...
Ah, he was just havin fun with post #4.
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