CLX-VU Build Thread (DBX 160VU ) UPDATE: REV 3
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plektra
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- Joined
- Feb 26, 2012
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- 6
I finally finished debugging, fixing and calibrating the first unit (I also had broken TL071s). Sound is pretty fantastic 
I'm still having some issues with the another channel, input signal becomes too hot at some point. No matter how do i turn the knobs, above threshold led is always lit. I've swapped all ICs between the two units and gone through basicly all solderings but the problem persists. I also tried isolating the board from metal riser pads, but no bonus. Any tips where I could find the point of failure?
I'm still having some issues with the another channel, input signal becomes too hot at some point. No matter how do i turn the knobs, above threshold led is always lit. I've swapped all ICs between the two units and gone through basicly all solderings but the problem persists. I also tried isolating the board from metal riser pads, but no bonus. Any tips where I could find the point of failure?
abechap024
Well-known member
plektra said:I finally finished debugging, fixing and calibrating the first unit (I also had broken TL071s). Sound is pretty fantastic
I'm still having some issues with the another channel, input signal becomes too hot at some point. No matter how do i turn the knobs, above threshold led is always lit. I've swapped all ICs between the two units and gone through basicly all solderings but the problem persists. I also tried isolating the board from metal riser pads, but no bonus. Any tips where I could find the point of failure?
Try calibrating the threshold...
Hi all
I have the same problem as plektra, one board no problems other board even with following the calibration procedure I cant get the above and below led to the off position, the above led is always on.
Any suggestions would be much appreciated.
Trampo
I have the same problem as plektra, one board no problems other board even with following the calibration procedure I cant get the above and below led to the off position, the above led is always on.
Any suggestions would be much appreciated.
Trampo
sr1200
Well-known member
Hey, ive been using my dual CLX for a few projects recently, and i started to notice a weird buzz (the paz meter shows it as a small spike at 70hz and from 10K up theres a weird wavy signal happening) ITS VERY minute, but would love a way to kill it if possible. Any thoughts?
abechap024
Well-known member
trampo said:
I would look at the RMS unit section. Try switching around the chips and see if that helps...
abechap024
Well-known member
sr1200 said:
Interesting. How do you have the grounding? Also what is very minute? -60db? -80db? -100db? that will help. Does it change with output gain?
sr1200
Well-known member
Followed the build manual to a tee, so however the grounding is there. It DOES increase with output gain. When set at 0 its gotta be below -60fs. But if i put a limiter on my mix bus it becomes pretty noticeable. (first i thought my monitors were humming since i recently re-located my power amp to the next room, thought maybe the cable run was too long) Again, not a huge deal since it is REALLY low (but i tend to mix pretty low which brings my noise floor into play). Has become a go-to comp on kick drum lately. I've been told to use it on snare which i've gotta try soon, but its gonna take a lot to convert me from my 1176 revD's.
plektra
Member
- Joined
- Feb 26, 2012
- Messages
- 6
We debugged this unit yesterday and there seems to be something strangely wrong with the another board. By an accident we discovered that the channel works well when following connections exist: oscilloscope measuring both input and output voltages between hot and cold wires and there is something connected to the output (in this case, output of CLX-VU was connected to a mixer input). When anyone of these is removed, signal is multiplied at an early stage so that above led is always lit. Odd is also that when one of the connections is removed, manipulating the output signal by turning threshold or ratio pots, it also affects the input signal measured straight from the input XLR connector...
The other channel is working and can be calibrated, so we swapped the boards (and also tried with one channel powered at a time), but the problem goes along the board, so this eliminates the possibility of broken/shorting wiring. Also it is not a grounding issue, because the another board works well with the same grounding schema. All chips have also been swapped between the units, problem persists.
I think next I'll go through the solderings once again and search for any possible solder bridges or dry joints. Any other ideas?
The other channel is working and can be calibrated, so we swapped the boards (and also tried with one channel powered at a time), but the problem goes along the board, so this eliminates the possibility of broken/shorting wiring. Also it is not a grounding issue, because the another board works well with the same grounding schema. All chips have also been swapped between the units, problem persists.
I think next I'll go through the solderings once again and search for any possible solder bridges or dry joints. Any other ideas?
abechap024
Well-known member
plektra said:
Super strange....hmmm so the problem follows the board? I would look for any solder problems/shorts, like you mentioned.
abechap024
Well-known member
sr1200 said:
Hmm -60fs seems pretty high. Does it do it with no input connected?
sr1200
Well-known member
I could certainly try tonight. It's currently hooked up to the patch bay.
abechap024
Well-known member
plektra said:
The parts numbers correspond to the original schematic if you find mine hard to read.
sr1200
Well-known member
Input in or not, buzz remains. At unity in protools, and the gain maxed on the CLX, im getting a peak signal at around -80. If i crank the gain in PT its clearly audible, and depending on the situation, it's noticable in the mix. I've put a link to the "noise" its not a normal 60cycle hum.
https://soundcloud.com/meistudio/line PS (dunno what that sound is at the end. it's never done that before it didn't go out thru the compressor or come FROM the compressor though)
https://soundcloud.com/meistudio/line PS (dunno what that sound is at the end. it's never done that before it didn't go out thru the compressor or come FROM the compressor though)
Ok, so the problem seems to be with the calibration. I used a more accurate tone generator, followed the calibration procedure and every thing lined up great with both sides. I did not change any components nor did i have any solder problems, just something to do with the calibration caused the output to be increased on one channel, must have just got lucky on one side and unlucky on the other.
The unit sounds great across a whole mix, drum bus and individual drums.
Many thanks Abe for a great product!
The unit sounds great across a whole mix, drum bus and individual drums.
Many thanks Abe for a great product!
shot
Well-known member
I have a problem with pin3 on the output.
There's almost no signal on it.
Output pin2 is ok, has full signal, but pin3 has signal so weak that it's almost non-existent.
I went tracing signal with probe around the output and found out that on the input leg of the R92 signal is full, but on it's output leg there's a big drop. Replaced R92 (22K1) in case it is somehow wrong, but that didn't fix the problem.
I then checked values of R103, R92, C35 and C32 and they all seem ok.
No cold solder joints also...
I don't understand...
help!
There's almost no signal on it.
Output pin2 is ok, has full signal, but pin3 has signal so weak that it's almost non-existent.
I went tracing signal with probe around the output and found out that on the input leg of the R92 signal is full, but on it's output leg there's a big drop. Replaced R92 (22K1) in case it is somehow wrong, but that didn't fix the problem.
I then checked values of R103, R92, C35 and C32 and they all seem ok.
No cold solder joints also...
I don't understand...
help!
