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

[jplebre]

Hi, sorry for the delay i've ben away.
Yes I use metal standoffs most of the time. I guess because it's what I've seen in a bunch of things and I just got used to it.
I had the exact same problem as the standoff/nut was touching the "via" pad and shorting it out through the standoff.

Thanks abe

 

[EmptyMusicBox1]

hi everybody

i just finish to made a CLX circuit the audio have a lot of High frequence ( 8KHz) andi have some problems ...

1-  the THRESOLD pot not working
2- the ratio pot work as a Volum pots
3 - I heard no compression

And i have a question : if i have no Switwhes wire the compressor is engaged ?

 

[berkleystudios]

hi everybody

i just finish to made a CLX circuit the audio have a lot of High frequence ( 8KHz) andi have some problems ...

1-  the THRESOLD pot not working
2- the ratio pot work as a Volum pots
3 - I heard no compression

And i have a question : if i have no Switwhes wire the compressor is engaged ?

double and triple check your wiring against the wiring guide... and then check it again for good measure.  if it  doesnt get better its probably staring you right in the face, thats what it always does to me haha

 

[ilfungo]

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

has anyone tried?
I would like to try but do not know how to do...
Thanks

 

[abechap024]

I did some more testing, and decided that as is, is the best 2180 chip implementation. The subtle differences between the 2180 and the 200 series vca I'm pretty sure I've narrowed that down to the VCA themselves and not how they are driven (I had a day of tweaking the circuits side by side an original 160vu a month or so back)

I am planning on somehow making 200 series VCAs again...maybe using THAT series npn/pnp transistor packages...stay tuned.....

I love the THAT VCA on stuff, but then the 200 series VCAs do have a certain charm for sure.

 

[sr1200]

Dumb question time.  I finally got my dual channel unit up and running, and was actually able to calibrate the meters and everything (WOO HOO!) 
1) i wasn't able to get down to the 0.011v in the calibration, any way around this or to remedy this?
2) i used spectra when dialing down the distortion, I got it down pretty low, but i notice a bit of bottom end missing when i start hitting the compressor harder than 2 to 1... is it possible I OVER did the dialing down?

 

[Trench Recordings]

I did some more testing, and decided that as is, is the best 2180 chip implementation. The subtle differences between the 2180 and the 200 series vca I'm pretty sure I've narrowed that down to the VCA themselves and not how they are driven (I had a day of tweaking the circuits side by side an original 160vu a month or so back)

I am planning on somehow making 200 series VCAs again...maybe using THAT series npn/pnp transistor packages...stay tuned.....

I love the THAT VCA on stuff, but then the 200 series VCAs do have a certain charm for sure.

did you remove the 5532 buffer circuit in your test  ?

 

[EmptyMusicBox1]

hi evererybody !

after many check i don't find my problem ...

the audio cross the Clx with no problem but i have no compression

-The GAIN pot is ok !
-The Threshold pot not working
- The Ratio Pot work as a "reverse" Gain
-i can't test the Switch because the Vu meter is alway to 0 ....

I have check the voltage on the Pin of the Led (Above) and i have 3v it's Normal ?

i think i have ICE dead but i can't find it

do you have "Voltage" point for check it ?

thanks for your help

My channel strip project is soon finished !

 

[shot]

Ok... I've hit a bump!
I've populated the pcb for CLX-VU Rev3 and everything is cool.
Now it's calibration. Dh...

I calibrated PSU and went without problems with RMS offset (used cubase as signal generator and it's multiscope for visualizing waveform). That went ok.

Than I probably did the distortion calibration done. I didn't understand it completely. I tried with RightMark, got varying numbers for THD. It all depends on what is the position of treshold. At 20db compression (max ratio and adjusted treshold to reach it) when I turn R34 trimmer I get gain change. When looking at FFT representation (used Smaart7 software to look and Cubase as sine generator) I see no difference in harmonic structure. 2nd and 3rd harmonic go up and down in relation with original signal (1rd harmonic) when I trim this resistor. Obviously, when I turn the R34 completely on the CCW i get lower THD measurements in RightMark, but also the signal is quieter. We're talking 10db range from CCW to CW on this trimmer. In RightMark I get like 3 or 4 value for THD. I assumed this was okay. But I don't know. Am I missing something here?

And the next step is really killing me. Level calibration.
Meter on input, 1.224vrms on input (balanced signal from my soundcard, measuring TIP signal on the input connector). At first I was getting random results on the right leg of R79 (usually too big values), but then I figured that if I set treshold CCW and R63 also CCW that it's allways -0.004vdc. So when I have treshold maxed high I can trim it to have -0.011vdc on R79. But as soon as treshold is lowered this value changes. It obviously depends on the treshold. And how can that be? Isn't it supposed to be independent of treshold position since we're calibrating INPUT voltage here? My switches are wired on 4x3 lorlin based on diagram posted by sr1200 on page 4 of this thread. And I double checked them. They seem ok.

Now when I want to proceed to treshold adjustment it makes no sense anymore! Since I had my treshold all the way CCW when adjusting (or trying to adjust!) level, I ended up with treshold point (both leds off) in that position. Makes no sense to put the treshold knob in this position since it cannot be turned more to the right. It's already CCW!

I stopped here. Didn't go through 1:4 ratio calibration and meter calibration. I wanted to ask first since it must have been my mistake in some step.

Any help?

Other than that, I think it performs great. Audio passes through, all controls respond, leds lit, it's clean (until extreme compression settings), noise floor sounds acceptable (didn't measure it yet). In all - super cool!



Luka

 

[abechap024]

Ok... I've hit a bump!
I've populated the pcb for CLX-VU Rev3 and everything is cool.
Now it's calibration. Dh...

I calibrated PSU and went without problems with RMS offset (used cubase as signal generator and it's multiscope for visualizing waveform). That went ok.

Than I probably did the distortion calibration done. I didn't understand it completely. I tried with RightMark, got varying numbers for THD. It all depends on what is the position of treshold. At 20db compression (max ratio and adjusted treshold to reach it) when I turn R34 trimmer I get gain change. When looking at FFT representation (used Smaart7 software to look and Cubase as sine generator) I see no difference in harmonic structure. 2nd and 3rd harmonic go up and down in relation with original signal (1rd harmonic) when I trim this resistor. Obviously, when I turn the R34 completely on the CCW i get lower THD measurements in RightMark, but also the signal is quieter. We're talking 10db range from CCW to CW on this trimmer. In RightMark I get like 3 or 4 value for THD. I assumed this was okay. But I don't know. Am I missing something here?

Yes...you just want to look at the screem with the 1k...the spectrum analyzer before you do any tests...you look at the 2nd harmonic of the bik 1k spike and adjust to lowest distortion. NOT A HUGE DEAL if you don't do this, I usually makes the 2nd harmonic go down a little bit.

And the next step is really killing me. Level calibration.
Meter on input, 1.224vrms on input (balanced signal from my soundcard, measuring TIP signal on the input connector). At first I was getting random results on the right leg of R79 (usually too big values), but then I figured that if I set treshold CCW and R63 also CCW that it's allways -0.004vdc. So when I have treshold maxed high I can trim it to have -0.011vdc on R79. But as soon as treshold is lowered this value changes. It obviously depends on the treshold. And how can that be? Isn't it supposed to be independent of treshold position since we're calibrating INPUT voltage here? My switches are wired on 4x3 lorlin based on diagram posted by sr1200 on page 4 of this thread. And I double checked them. They seem ok.

Ok, with this one, I only have luck with the meter on "INPUT" mode. Level should not fluctuate depending on how you have the controls. Make sure you are actually probing r79 and not the other one close to it, and the leg towards the output transistors.

Now when I want to proceed to treshold adjustment it makes no sense anymore! Since I had my treshold all the way CCW when adjusting (or trying to adjust!) level, I ended up with treshold point (both leds off) in that position. Makes no sense to put the treshold knob in this position since it cannot be turned more to the right. It's already CCW!

yea...something isn't right. Go back to your threshold adjustment... Also don't worry about it too much. If you can't get an EXACT reading of -0.011v for whatever reason, put a 0db signal on the comp turn the threshold knob like 1/8th of the way counterclockwise and set the trimmer so the GR lights go out.


Good luck!!

 

[shot]

Huh! I'll try it.
Thanks Abe!
I'll keep you posted after I try again.

 

[shot]

DAMN! I just had a disaster!
Two caps in the PSU section (C42 & C43) blew like firecrackers!

I went to try to calibrate the thing. It was working on a bench for few minutes, passing signal. All seemed ok. I don't know what precisely happened. In a moment, without me touching anything signal I was playing through the unit became very loud. And then those two caps exploded. One by one. I quickly unplug the main, and started visually inspecting whole board. Everything seemed ok. No solderleaks or anything. The board was on the wooden table with a piece of paper underneath it. No small metallic dust or debris under it. Very clean non conductive surface. So I guess it wasn't a short caused by something outside the board.

I cleaned out those two caps (what was left of them) and pulled out all the ICs. Then I replaced those caps and slowly visually checked the board for any obvious error. It seemed ok, so I plugged it again into mains power. Again one cap blew. This time only C42. I guess I unplugged the whole thing before it had time to blow the other cap.

What should I do now?
I tried continuity check with a DMM and as far as I can beep there are no shorts in the PSU section.
I guess I'll try to replace the positive regulator (both caps that went ka-booom are in the positive rail)... Is there a way to test if it is actually a regulator issue?
But what else!
Guys please help me out!

 

[abechap024]

DAMN! I just had a disaster!
Two caps in the PSU section (C42 & C43) blew like firecrackers!

I went to try to calibrate the thing. It was working on a bench for few minutes, passing signal. All seemed ok. I don't know what precisely happened. In a moment, without me touching anything signal I was playing through the unit became very loud. And then those two caps exploded. One by one. I quickly unplug the main, and started visually inspecting whole board. Everything seemed ok. No solderleaks or anything. The board was on the wooden table with a piece of paper underneath it. No small metallic dust or debris under it. Very clean non conductive surface. So I guess it wasn't a short caused by something outside the board.

I cleaned out those two caps (what was left of them) and pulled out all the ICs. Then I replaced those caps and slowly visually checked the board for any obvious error. It seemed ok, so I plugged it again into mains power. Again one cap blew. This time only C42. I guess I unplugged the whole thing before it had time to blow the other cap.

What should I do now?
I tried continuity check with a DMM and as far as I can beep there are no shorts in the PSU section.
I guess I'll try to replace the positive regulator (both caps that went ka-booom are in the positive rail)... Is there a way to test if it is actually a regulator issue?
But what else!
Guys please help me out!

Caps will only blow if they have over-voltage or reverse voltage. I'll state the obvious and see if they are installed backwards?

 

[shot]

Yeah. I know. But I'm 100% sure I didn't insert caps backwards!
I still didn't get to debugging this situation. I work slow since I don't have a lot of spare time, so please bear with me

I haven't replaced regulator yet. I just tested power transformer and it's output is ok.
But what if regulator turns out okay? There are those diodes that are supposed to protect regulators (CR20 & CR21 on positive rail).
Thinking ahead - if regulator proves not faulty, my next step would be to isolate the PSU section and test it individually. Is there a way to do this? Cutting traces or just removing a component or two?

 

[abechap024]

Yeah. I know. But I'm 100% sure I didn't insert caps backwards!
I still didn't get to debugging this situation. I work slow since I don't have a lot of spare time, so please bear with me

I haven't replaced regulator yet. I just tested power transformer and it's output is ok.
But what if regulator turns out okay? There are those diodes that are supposed to protect regulators (CR20 & CR21 on positive rail).
Thinking ahead - if regulator proves not faulty, my next step would be to isolate the PSU section and test it individually. Is there a way to do this? Cutting traces or just removing a component or two?

Well....you shouldn't need to isolate it if you pull all the chips out...I would measure the voltage were the caps are blowing...very strange problem that can only be caused by over voltage, bad caps, or put in backwards. You aren't putting them in backwards. So maybe measure the voltage...see if somehow its over, or somehow the voltage is inverted??

 

[shot]

It's always human error!!
(Abe is not to be considered human...he's from space! )

I found what was the fault. I've put two heatsinks on regulators and forgot to install the isolator between regulator and heatsink.
When two heatsinks made contact that's when caps started popping.

Ok, I fixed that.
Now I have to fix the aftermaths. Unit is not passing audio and I don't have offset signal on RMS detector. Also, THAT IC is having -2v supply on pin 5 when inserted. When out, voltage is ok (-15v).
One of the IC went dead. I'll try to replace all ICs in RMS and see if it's one of them and if it is affecting THAT's v- supply.
Keeping my fingers crossed it's not THAT IC since they are hard to obtain in my country...

Keep you posted.

 

[abechap024]

It's always human error!!
(Abe is not to be considered human...he's from space! )

I found what was the fault. I've put two heatsinks on regulators and forgot to install the isolator between regulator and heatsink.
When two heatsinks made contact that's when caps started popping.

Ok, I fixed that.
Now I have to fix the aftermaths. Unit is not passing audio and I don't have offset signal on RMS detector. Also, THAT IC is having -2v supply on pin 5 when inserted. When out, voltage is ok (-15v).
One of the IC went dead. I'll try to replace all ICs in RMS and see if it's one of them and if it is affecting THAT's v- supply.
Keeping my fingers crossed it's not THAT IC since they are hard to obtain in my country...

Keep you posted.

Glad you figured it out. Now that you have all the voltages correct, you could take all the chips from your working board and put them into your other board and double check its working. Then one by one switch out the chips to see which one(s) are fried. In my experience THAT chips are pretty sensitive to over-voltage/wrong voltage....but if you need one let me know I am ordering some and could send you some and any chips you need at cost, if that makes it easier. Also the CA3083 chip might have been blown.

 

[shot]

Thanks Abe!

I only have one board so I'm unable to do the swap test.
Today I bought all the chips except THAT but it's late night now, too late to test. I'll do that tomorrow.

Thanks for your offer on ICs! I hope it won't come to that. I'll let you know!

 

[tfp]

Hi Guys,

Some pictures of my finished 160. What a compressor...!!!!

Thx very much Abe!

 

[tfp]

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