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

[jplebre]

@late, these guys a very different beast when compressing kicks. shall we do the same?

 

[late]

@late, these guys a very different beast when compressing kicks. shall we do the same?

Sure. Post tracks and i do same things with your kick track?

 

[jplebre]

@late, these guys a very different beast when compressing kicks. shall we do the same?

Sure. Post tracks and i do same things with your kick track?

Game on! edited my previous post with BD samples.
Some spill, but that's the way I roll

 

[late]

Edited my old post too. What you prefer 2180 or silver can?

 

[jplebre]

on snare I have to say there's a difference. I feel it's the difference I heard yesterday with the originals
the extra distortion does give it a cool character.

On kick I'm not sure if I would go through the trouble or the extra £ for the slightly softer difference

All in all pretty close. Even to the originals. the original seemed to be a "tad" faster maybe because it would have an old cap and it could be off callibration (trim) or leaky due to age?

 

[abechap024]

Someone should build one with all the original resistor values, completely bypassing the Ne5534 CV buffer and go straight into the THAT 2180 chip...I've wondered about doing this and think it might lead to some interesting results (I might do it soon when I get some time!)

I know the THAT2180 likes to be driven from a low impedance source, hence the ne5534, but the original RMS unit is driving from a 200ohm impedance, which isn't horrible and we aren't exactly looking for pristine anyway...hmmm, I bet the 2 resistors that set the impedance could even be modded some what too....been on my mind to try..something to think about...

great audio samples guys, I've been meaning to build up some with the silver cans too. I'm getting my hands on an original 160vu here in the next month or so, and I should run some in depth tests on it. Last time I had one, I only had time for quick audio analysis.

But I've found, that the CLX has been our studios go to snare and kick compressor, but we can only use it when the lights are blinking and meter twitching, it adds a really nice controlled snap to everything. The times I haven't used it during tracking, the drums never sounded as impressive. Also it is VERY easy to destroy drums during tracking if used like a regular compressor (having the meter move more than a twitch) because the meter has such a huge GR range, anything more than a twitch on a transient, your digging into -15 to 20db on aggressive peaks.

On bass and vocals and guitar, digging in is fun

 

[nuclues]

Is C 39 (100pf) omitted or should I put a 100 pf in there?
Just to be sure, those resistors marked with a (T) on the pcb :

Should I use the value at the right side,when I use the That vca,right?

Best regards from Nick

 

[abechap024]

Is C 39 (100pf) omitted or should I put a 100 pf in there?
Just to be sure, those resistors marked with a (T) on the pcb :

Should I use the value at the right side,when I use the That vca,right?

Best regards from Nick

On C39 you want to put the 100pf in there.  And yes you got it, use the value on the right side, next to the (T).
Good Luck!

 

[nuclues]

Thanks Abe

 

[Trench Recordings]

I just want to verify my above below led circuit is working correctly. When I input a +4dBu signal, threshold above lights up when fully CCW and turns off at about ".03" or a quarter of the way up. After that I cant get the below to light up. Not even fully CW.

If I have no signal the below led turns on from half to fully CW.

Does that sound right ? Also between the two dual units the led above and below set points are slightly off compared to each other. Anyway to adjust that in the circuit ?

 

[jplebre]

something is wrong. The anode of one and the cathode of the other go to ground, and the other leads follow the PCB writing.

With +4dBu the above light should be lit untill 1 (slightly above 1, technically, both LED will be off as this is the treshold +4dBu=1.23v). After that, the below light would take over

 

[Trench Recordings]

oops, pin 1 and pin 2 reversed on pcb connection. Led's working great now thanks jplebre

the threshold between the two units are slight off. I adjusted it with the knobs to match but is there an adjustment for this ?

 

[jplebre]

Nope that's it! shoot 1.23v (+4dbu) turn treshold until both lights go off, unscrew the knob and screw it back so it points slightly above 1 on the faceplate

 

[Trench Recordings]

Ha, can someone help me troubleshoot. I was having an intermittent distortion on one dbx, only when I flexed the case or grabbed a knob a certain way. So I figured it was a cold solder somewhere. I first swapped all wiring from one board to the next. Problem stayed. Then swaps all chips, problem stayed. So it must be in the board. I pulled the board and reflowed all the joints. Now the problem is constant.

I have a scope and signal generator. I don't really know where to probe in the schematic ?

Right now I input a 1.22v sinewave and get out a lower volume square.

 

[Trench Recordings]

R92 looks good sine, R83 good. R84 and R89 Squarewave

Readinng 2.6Vdc on one end of R85, and 27Vdc on the other end of R85. If i pull lm301 it goes back up to 21Vdc

voltages low on R86 and R87 too

 

[abechap024]

R92 looks good sine, R83 good. R84 and R89 Squarewave

Readinng 2.6Vdc on one end of R85, and 27Vdc on the other end of R85. If i pull lm301 it goes back up to 21Vdc

voltages low on R86 and R87 too

Seems like your on the right track...If its the output stage, double check R85, and R95, make sure they are 2k2, measure at the LM301 opamp that the voltages are correct, you should see some voltage drop but not that much.

Also you can try to trace the signal on a leg of C21 see if its distorted there...if it isn't then you can rule everything before the output stage out...

 

[jplebre]

Hi
I had distortion on the O/p stage because I was using metal stand offs. Was bugging the hell out of me because as soon as I lifted the board to make it easy to probe the distortion would be gone.
I ran it for a few hours w/ electrical tape under the O/p standoff hole and it was fine, just I just stuck a nylon washer there and good to go!

Abe, if you ever do a revision, can you give more space from the O/p, I/p and Power molex terminals? was very tight to use 1-4 nut sets to tighten it (in fact I don't think I managed to put it on the power hole.

Cheers!

 

[Trench Recordings]

the metal standoff was grounding something?

 

[Trench Recordings]

Bingo! that little TP that goes to C25 by the output standoff must have been grounding out. Thank you so much Jplebre. I would never have thought to test the board off the standoffs like that. I spent hours troubleshooting last night

 

[abechap024]

Bingo! that little TP that goes to C25 by the output standoff must have been grounding out. Thank you so much Jplebre. I would never have thought to test the board off the standoffs like that. I spent hours troubleshooting last night

Glad you got it figured out. I always use nylon spacers so I never would've thought about it. Good call for next revision.