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

[Songguy]

Thanks Abe,
I notice that in both of my board kits I have an extra 150pf ceramic after populating C22, C82 and C14 with the designated 150pf's.

 

[abechap024]

Okay, I must of added 1 more to your kits without realizing I already added them. Sorry for the confusion. Maybe they will come in handy someday?
Cheers,
Abe

 

[Songguy]

One last capacitor question.

optional capacitors: C39  NEEDED FOR THIS BUILD 100pf OPTIONAL

Can you tell me why this may be optional? It reads a bit ambiguous to me.

Thanks for taking the time to answer my noob questions.

Chris

 

[abechap024]

The original didn't use one but I found it necessary when interfacing with the THAT chip.

 

[abechap024]

I have mine working now, but I still can't get the scaling on the meter to work properly.  I would be interested to know from anyone else whether this lines up properly for them ?  R56 & R59 trimmers seem to do nothing.  Is anyone else experiencing this ?


Apart from that it's great, thanks Abe for a nice project, I appreciate the amount of work you have put in on this.

Okay Updates! :


To get the level calibration to work correctly (measuring 0.011v or 11mv on the inside leg of R79 with 1.228v input sig)  I found you need the meter reading "input".

Also if using the hairball 1ma Meter you need to put in a 3.3k resistor in the resistor spot instead of 1k.

Annnnndddd more to come I imagine...

 

[Songguy]

hi all,

can you tell me if i have the right idea for the parallel wiring. Ive never wired 2 boards to one trafo before.
check the pic.

cheers,
Chris

 

[abechap024]

Yep thats correct!
They look like they are in parallel which is what you want.

Cheers

 

[Songguy]

here is a pic of the trafo/switch wiring using the antek audio trafo. thanks for checking my work Abe 

 

[slowbass]

Hello,

I've finished my dual clx and it works fine but I have three questions :
- is the 3k3 resistor with the hairball meter really important + the calibration in input mode ? how does it affect the meter ? because I don't feel like deracking, opening and desoldering the compressor !
- how do you wire two units for the stereo mode ? it's not in the instruction manual
- while calibrating the ratio, R43 almost didn't change anything on both units...

Thanks again for this very cool project !

 

[abechap024]

Ah Cool!

Well the 3k3 resistor is necessary for more accurate meter functionality. I found with the 1k meter doesn't scale correctly. BUT that being said if you just plan on leaving your METER in GR mode then leaving in the 1k shows you more of whats going on.

For stereo mode you want to wire the switch to connect both timing capacitors together (22uf tantalum caps) connect the pins that aren't connected to ground.

R43.....yea now that you mention it, it didn't change much on mine either, but my 4:1 was pretty close, so I didn't think about it too much. why it doesn't work is a mystery it is all hooked up correctly

Well I take that back!!
Just looking at the PCB board, looks like the center wiper isn't connected to the 7.5k resistor correctly. I don't know how that happened because its correct on the schematic. So if your looking at the board Straight on with the writing up, solder blob the left pin and the wiper pin together of r43

Weird! It doesn't seem to effect the sound and calibration of the unit that much. But glad we caught it.

 

[abechap024]

Also seems like 500ma fuses aren't enough for repeated power cycles. Even Slow-Blow are randomly tripping on power up.

I am now using 1A fast-acting.

No problems

 

[nebula]

Abe, one of the first things I did when I started building is put a 150 pF cap in C39, following the instruction on page 18 of the build guide.  As I am finishing up on populating the board, I noticed the BOM (and discussions here) say it should be 100 pF.

I'm still puttering through getting the boards done, but should I plan to leave the 150 pF in place, or should I swap it out for a 100 pF?

 

[abechap024]

Hello, 150pf for c39 is perfectly fine. That opamp buffers the DC voltage, so its bandwidth does not have to be very large at all!

(thanks for pointing that out I'll fix it on the build manual)

Thanks,
Abe

 

[nebula]

Abe,

C13 is marked on the board as a 22uF electrolytic, but not mentioned in the BOM.  In the hi-res pic of a completed unit posted elsewhere, the capacitor is present.  Is it necessary?

Thanks

 

[abechap024]

Hi, Nope not necessary. Its for the discrete VCA and just goes between the power rails.

-Abe

 

[Winetree]

I'm using the 4 gang meter switches from Hairball.
If you use the first one for power, then every time you press another switch,
it releases the first one turning the power off.
The first switch doesn't have it's own latch and uses the release bar to keep it engaged. This is the big black switch.
It  also says you can use the channel 2 one for a stereo link switch, having the same problem.
What to do?

 

[abechap024]

You need to wire the power switch like on the 1176, when you push the power button when you want to turn it off, and selecting a meter mode will turn the unit on. All you have to do is switch whatever pins you have the AC power on.


For the Stereo link, you have to press both the link and the meter function you want, I wish there was a more elegant solution than this, but it works.

 

[Winetree]

OK, Went out into the studio and turned on an 1176.
Any meter select turns it on and the power button turns it off.
My idea was to  unlatch the power switch from the latching bar and make it latch independantly.
The switch has provisions for the little plastic latching bar inside, it's just not there.
That way the power switch would latch off and on and not be effected by the others. Same for Link.
So much for practial thinking.
Is there a diagram for what your talking about. I haven't found any of this in the manual.
Thanks.

 

[abechap024]

Hi sorry,
I misunderstood you. If your using hairballs switches there is no way to unlatch them and if you could they would just be momentary switches.

The simplest was to do it, is make sure the power button is the OUT position and with DMM find 2 lugs that show no resistance, then push the switch IN and then make sure the resistance goes to infinite.

Then solder your power to those.

I think thats what your asking right?

Cheers,
Abe


PS Check out Chris's drawing just a few posts above this ^^^

 

[abechap024]

Hi All,
Well got REV 3 done, easier to build, new manual is up.

Thanks!

Abe