dbx 160vu clone

[Biasrocks]

Mark,
if you still have the board and VCA on your bench could I get some measurements on the VCA to tighten up the pin spacings?
Thanks
AC

Sure thing

Module size is the same as the RMS detector

Pin width

(PO to OUT) 2.55cm, same as 208 RMS detector.

V- to V+: 1.5cm
V- to No: 1.5cm
No to Out: .7cm

In to Gnd: 1cm (*Shield (COMP) is bent inwards and soldered to the case inside
                        but pin spacing would be .5cm if used)
Gnd to Px (P1): .5cm
Px to Nz (N1): .5cm
Nz to Po(SYM): .7cm

Also sent you the 160/161/162 service manual.

Mark

 

[abechap024]

Hi,
Just making a list on here that I will edit periodically as peoples opinions keep coming in. That being said if you have any suggestions please make yourself heard.
These are the planned revisions for PCB Rev.2:

1) option for bigger power supply caps. (bigger foot print with the smaller footprint inside)

2) Via holes further away from Solder holes ( some of the vias get close to solder pins and possible solder bridges could cause headaches)

3) 4.7uf Bi-Polar output coupling cap have option for a Film cap

4) Make Mounting Holes Bigger!

5) Option for Matched transistor array in Discrete VCA for easier discrete VCA building (circuit has yet needs to be tested with whatever transistor array people think might work)

6) also depending on pending listening tests / opinions - might opt for lm317 style on-board power supply

7) Fix pin spacings for original DBX rms/vca units (done thnx baisrocks)

8) Make board size compatible with 119 case.

Thanks!

Abe

 

[Biasrocks]

I'll add to the list Abe,

It would be super cool if the board size stayed small enough to be mounted in a 119 (or similar) enclosure since I happen to have a carcass sitting here next to me.

I can verify the measurements if you're interested.

I actually think that you're pretty close right now, with maybe slightly different mounting holes.

Mark

 

[abechap024]

I'll add to the list Abe...

...I can get verify the measurements if you're interested.

Yes, thats a good thought. Talk about a 119 "upgrade" ;-)!! Probably has all the right controls on front too?? If you could send me the measurements and mounting hole placements I'll shoot for it.

And we might have to scratch that Old powersupply (with the 4x Transistors that are relatively expensive! and bulky!) But wanted to prototype the original power supply just to not take anything for granted...at least once!

- Updated List
AC

 

[Biasrocks]

119

PCB size: 20cm x 12.5cm (already in the ball park)

Back mounting holes: 5.5cm & 10.1cm looking at the bottom of the board, from back to front. It's 60mm from the back panel.

Front is mounted to the back of the control pots, so we'll have to devise a way to support the front, perhaps from underneath as there's a 80mm flange that sticks out from the front panel, about 1cm below the pcb.

I'll take some photo's so that you can get a good visual of how it's situated.

Mark

 

[damnyankee]

The 200VCA module from my 119 fit the board, albeit with a bit of stretching of the pins, definitely not a comfortable fit but doable.

The 208RMS module on the other hand didn't fit at all, in fact it appears that the pinout is slightly different between the 208 and 209 modules.

How the hell did you manage to fit it into the current footprint, do you have a 209 or a 208?

208RMS Mod measurements:

Module Width: 3.7cm
Module Length: 4.8cm

Pin spread width (Pin 1 to Pin 9 / Pin 4 to Pin 5): 2.5cm

Pin seperations

Pins

1 to 2: 2.5cm Actually this is 2.55cm, verified on the board
2 to 3: .5cm
3 to 4: .7cm
5 to 6: .7cm
6 to NC: .5cm (*Sits over R44 on PCB)
NC to 7: .7cm (*Sits over Q2)
7 to 8: 1cm
9 to 10: .7cm

Mark

Mark,

My 208 did not fit right away - it had 5 legs on each side of the can.  When you look at your pins on your 208 RMS, do you have 5 pins coming out on the bottom of each side? 

DY

 

[Biasrocks]

My 208 did not fit right away - it had 5 legs on each side of the can.  When you look at your pins on your 208 RMS, do you have 5 pins coming out on the bottom of each side? 

No, I have 6 pins on one side and 4 pins on the other.

Mark

 

[damnyankee]

I'll add to the list Abe,

It would be super cool if the board size stayed small enough to be mounted in a 119 (or similar) enclosure since I happen to have a carcass sitting here next to me.

I can verify the measurements if you're interested.

I actually think that you're pretty close right now, with maybe slightly different mounting holes.

Mark

I thought about this and decided not to go down that road because of space.  It's just easier to get one transformer to power two boards in 1 rack and VOILA!  Dual mono 160VUs.

My issue was, "how am I going to get the knobs to fit???"  As I was thinking thru it, I would have to take off a 1/2" off the left side and 1/2" off the right side. That would leave me 4" of workspace.  If I subtracted 2" to accommodate the VU meter, I discovered I'd be left with 2" to place my Threshold, Compression, Gain, Power, and Switches controls.  I did a quick image and looked at it and went, nah...nice thought, but it's not going to work for me purely from an asthetics standpoint.  I have an image for you so I'll send it to AC for him to upload.

DY

 

[damnyankee]

My 208 did not fit right away - it had 5 legs on each side of the can.  When you look at your pins on your 208 RMS, do you have 5 pins coming out on the bottom of each side?  

No, I have 6 pins on one side and 4 pins on the other.

Mark

Oh that's right - it was 6 pins and 4 pins.  When you flip the can upside down and look down on the pins onto the component, the row of 6 pins is on the bottom.  Reading across the pins from left to right, the 4th pin from the LEFT has to be snipped...like this one: (see image on top right of page)

http://www.cmaudio.net/forum/dbx160%20208-209%20rms%20module.pdf

Now, AC helped me trace where this goes on the 119 pcb.  If you notice, the tracer to the pin comes from a resistor.  The tracer that leaves the pin goes to a hole in the pcb that goes to nothing.  Check it out.  Once you snip that pin or bend it in half to get it out of the way, you'll have no problems bending the other pins so the 208 RMS will fit.  Piece 'o cake!

;D

 

[abechap024]

The pin in question goes to the "+" input on one of the op amps and on the schematic the "+" input only goes from a 1k resistor to ground, The Schematic shows no purpose for this pin.

Yes, there was one pin that we figured must be for a trim or something...


I feel I'm not being very fluent on conveying that thought but if you look at the link DY posted it should make sense

AC

 

[damnyankee]

Mark,

Did you resolve your 208 RMS pin issue so it would fit on the board?

DY

 

[abechap024]

Hey Danderloo just had an Idea.... What If we just build a blend control right into the circuit board? I'll look into it, but for people that don't want a blend they would just install a jumper or something.

I'm a big fan of what paralleling thing does for sound.

Thoughts?

AC

edit: been emailing back and forth...a HPF side-chain option would also be nice. If there can be an easy way of implementing it without making the board cumbersome for people that don't want to use the MIX/HPF I want to add it. and getting rid of the old power supply will leave plenty of room with out changing the size of the PCB too much

 

[damnyankee]

AC,

Personally, I'm fine with your faithful reproduction of the 160VU.  Plus you've have added an option for THAT chips to avoid the hassle of matching transistors for the VCA and you've included space for an alternate power supply.  I believe for Rev 2 that you planned on making the pcb a little larger like the original 160VU - so space between components isn't as cramped so those who want to do mods, there's some space to do it.  For me? I'm good with Rev 1 and the upcoming Rev 2.  Either/or is fine with me.

Be aware you can continue to do board revisions to add high pass filters, blend controls, trafo ins/outs, etc etc etc but then you'd end up with a modded 160VU which probably isn't what you started out to do: create a faithful reproduction of the 160VU.  

DY

 

[Biasrocks]

Be aware you can continue to do board revisions to add high pass filters, blend controls, trafo ins/outs, etc etc etc but then you'd end up with a modded 160VU which probably isn't what you started out to do: create a faithful reproduction of the 160VU.  

+1

 

[abechap024]

Ok,

I spent the last 15 minutes writing out a reply that was basically just me debating back and forth adding the different options.

I for one don't have a lot of extra buses on my console for I really LIKE the idea of a mix knob built right into the compressor. But on the other hand, if the diy1176 would've had a mix knob built right into it, it would just complicate the build and everything else THAT much more.

So, for now it still is DIY. I'll make the PCB and THEN whoever wants (me) can work out different mods. I love mods so this is a hard choice, but I always tell myself to try and KEEP IT SIMPLE. (hard sometimes!)

-Plus just found this awesome place has an internal crush/blend thread http://www.groupdiy.com/index.php?topic=31246.0

 

[abechap024]

....So anyone building this unit?? I sent out 10+ units...I'm not in the position to work on my unit right now (dorms)
I'm extremely interested if someone builds one....

Keep us Posted!

p.s. On the PCBRESDEF.jpg I fixed an error on the "ALt. Power in" molex desinations. I had the +/- pins labeled wrong. The correct one was posted yesterday, but if someone downloaded the old drawing and then used an off board power supply and then didn't catch the in that drawing the +/- are labeled wrong then bad things could happen!

Thanks
AC

 

[damnyankee]

....So anyone building this unit?? I sent out 10+ units...I'm not in the position to work on my unit right now (dorms)
I'm extremely interested if someone builds one....

Keep us Posted!

p.s. On the PCBRESDEF.jpg I fixed an error on the "ALt. Power in" molex desinations. I had the +/- pins labeled wrong. The correct one was posted yesterday, but if someone downloaded the old drawing and then used an off board power supply and then didn't catch the in that drawing the +/- are labeled wrong then bad things could happen!

Thanks
AC

Hi AC,

I d/l'ed the corrected pcb board layout - thank you!  I just got my parts in from Mouser about a 1/2 hour ago.  So tonight I'm going to solder in the sockets and check the diodes & resistors.  Tomorrow, I'll start soldering those in.  The VCA & RMS cans need some friends on that board!!!

DY

 

[damnyankee]

Ok, started to populate the power supply section on the board...

For Rev 2, you will probably want to provide some more space between D13-D16.  They are crammed together (side by side) and the leads into the board from the diode bodies look similar to a magnetic field. *LOL*  It's doable, but you'll definitely want more space.

Also, the 25V 4700uF Panny FM filter cap mods at C36, C37 is common for all these early dbx compressors (including dbx 117, 118, 119, etc)...you will need more space to accommodate that mod.  I have to think about how to accommodate those caps.  
QUESTION: I can insert a 4700uF at C36, but for C37, can I have 1/2" long lead legs (25V 4700uF cap mod) coming out of the board and bend C37's cap body sideways over Q7 & Q11?

Speaking of Q7 & Q11: the solder joint holes to accommodate the NTE159's are extremely small...it's a very tight fit.  In fact, I had to use needlenose pliers to pull the leads through the pcb.  I prefer solder to go through the other side of the board and this clearly isn't going to happen.  So I soldered from up top as well but I'm going to identify these solder joints a potential troublespot for solder joint weakness.

One last thing: I noticed another typo on the board (other than the two R-18's): D18 is labeled 1N9608 and the part is 1N960B.

Other than those minor issues, populating the power supply sections is going well.  Nice job, AC!!!

 

[envelope]

please use 35V minimum. 25V is not enough
...please use 35V minimum,  (for +/-24V supply)

 

[damnyankee]

please use 35V minimum. 25V is not enough.

This is my first non-9V pedal build.  So I'm trying to understand "why" as I step thru the process.  Ok, the stock filter caps are 25V 470uF.  I thought filter caps should be minimum 1.5x the voltage, so 15V x 1.5 = 22.5V minimum for the filter caps.  Is that calculation wrong???

Thanks!

DY