CLX-VU Build Thread (DBX 160VU ) UPDATE: REV 3

[Spencerleehorton]

Vu meters seem to be responding now, and  I have the distortion software so I can test and setup.

Spence.

 

[Spencerleehorton]

Getting hum on one unit no output apart from hum sound, going to replace TL082 IC's for TL072 or OPA2604.
Other unit passes audio to output, unit compresses but output gain when turned CW cuts out signal.
So need to get to the bottom of that?

Spence.

 

[Bowie]

Getting hum on one unit no output apart from hum sound, going to replace TL082 IC's for TL072 or OPA2604.
Other unit passes audio to output, unit compresses but output gain when turned CW cuts out signal.
So need to get to the bottom of that?

Spence.

I'd check my wiring on the pots.  Also, move the PT around to see if that affects the hum.  I was able to get pretty much zero hum by situating the torroid just right, though that may or may not help your specific problem.

 

[Spencerleehorton]

I'm pretty sure the hum is the fact that I have blown the TL082 IC's, once I change them I will hopefully get output rather than hum.

Spence.

 

[Spencerleehorton]

The power txf is in a separate box so it won't interfere.
Changing the TL082 for the OPA2604 hasn't improved the problem, need to put a signal in and start tracing the signal to find out why it's making this hum.
On the other unit I had the output pot wired wrong, but now wired Correctly it works but I only get a beep out of it at about 3/4 CW, so also need to trace signal and see what it doing.

Spence.

 

[Deepdark]

Hi guys

Is anybody know what happened to AC sounds? I just came through their Facebook and things don't quiet looks god

 

[Spencerleehorton]

I think he has been having some quite serious personal issues.

Spence.

 

[Bowie]

Hi guys

Is anybody know what happened to AC sounds? I just came through their Facebook and things don't quiet looks god

You can get the boards and cases through Dan Deurloo @ CollectiveCases.com.  He's 100% reliable in my experience so you don't have to worry about the issues AC sound had.

 

[Spencerleehorton]

Why did no one tell me I wired the switch wrong!,
Hopefully this is right now.

Spence.

 

[Spencerleehorton]

i'm totally foxed by this switch now!!! can anyone suggest a way to wire it using a 3 gang 3 position switch please?

regards

spence.

 

[Spencerleehorton]

the only thing i can think of to come up with is this:

IN position seems to feed pins 1,2,3,5,6
GR positions seems to feed pins 1,2,5,6,7
OUT position seems to feed pins 2,3,4,5,6,7

so i'm trying to figure out how i can do this with only 3 gangs?

 

[Spencerleehorton]

using the 3 gang i've opted just to use IN and GR as i can accommodate this on there.
need to run through the setup procedure again.

Spence.

 

[Spencerleehorton]

Matt Nolan very kindly drew this out, thanks Matt.

Spence.

 

[Spencerleehorton]

switches wired correctly now, have found the problem with one of the units.
TL071 pin 2 is 5.52v and needs to be around 0.552v also pin 1 of 4558 is 0.817v and should be around - 0.177v
both led light are on with all IC taken out.
any ideas anyone?

regards

Spence.

 

[Spencerleehorton]

missing diode fixed the 4558, still looking for why pin 2 of Tl071 is 5.51v?

Spence.

 

[Deepdark]

wrong resistor value? A short/bridge around?

 

[Spencerleehorton]

Swapped the TL071 and the unit works perfectly!!
Now to set them both up!!!

Regards

spence.

 

[Spencerleehorton]

Also a little note to everyone, the 3 gang switch arrangement works perfectly!!! Thanks again Matt Nolan, another great idea of his!!!

Spence.

 

[critterkllr]

Has anybody compared this with an original DBX 160? One thing that caught my attention was that the power supply circuit has been updated and improved. I'm wondering how much this affects the sound.

Who knows if this has any merit, but I did find this quote on gearslutz:

"The 160VU enhances the attack of snare and kick by expanding 15 to 20 milliseconds before the onset of compression..(as revealed to me by LesTyler its' designer)...as a product of its poor powersupply..which also can be seen in the slight dimming of the lamps on every beat "

https://www.gearslutz.com/board/high-end/17460-dbx-160-vu-compressor-best.html - post 15

 

[critterkllr]

I could use some help calibrating this. This is the most confusing calibration I've gone through on any of my compressors.  I've searched, but everything is hidden in stacks of math and I have no clue what applies to me. I have a signal generator, an oscilloscope and a DMM. There is no RMS setting on my DMM.

1) How do I measure to know the signal is -60dB? My signal generator has an attenuators that goes to -50dB along with an amplitude pot. There is probably some AC voltage I could read on my DMM right?

2) How do I set my oscillator to 100 Hz 1.228 VRMS? My oscope has an Cyc RMS measurement, but it just jumps from 1.1V to 1.4V constantly.