dbx 160vu clone

[damnyankee]

AC, you may be right about the "sag" in the power supply. From another poster from another board:

"...I love the DBX 160VU set so that the light just barely flicks on during the transients. The sound you get is a subtle but incredibly effective "sticky" snap to the attack. Its just an assumption but I think what is happening is that the power supply is under designed and when the transient hits it causes a slight sag just after the transient comes through which causes the audio to duck just slightly giving that 'sticky' sound. In reality it doesn't compress much of anything so it is more of an effect..."

 

[abechap024]

damn damn. ok well power supply looks like its back on the chopping block...

well then I say we leave the stock 470uf in there instead of the 4700uf upgrade. Adding more capacitance would increase that Stability and power reserve of the unit.
Can anyone verify this claim that the attack "stickyness" comes from power supply sag and not the compression itself?
AC

 

[damnyankee]

AC,

I created an image file consisting of the top & bottom 160VU pcb that Matthias kindly provided.  It's actually pretty slick.  We should be able to determine where those 10 leads go. 

The issue is, I don't know how to upload an image for this board.  I don't think using

is going to work.  And, the Help section wasn't exactly help.

Please advise.

DY

 

[abechap024]

You have to upload it to some soft or image hosting
google free image hosting
I'm ordering some prototype PCBs right now.

 

[damnyankee]

That was fast!  By chance, did you incorporate the original power supply or did you insert jumpers?

 

[damnyankee]

Let's see if this works...

 

[abechap024]

Actually changed mind on the prototypes just yet. Still want to double check. Finished power supply...After looking at the info for the 723 I am almost positive of the pin locations...

www.imageshack.com <--they should host your images. or just email them to me abe(at)acsoundstudio(dot)com I'll post them
Thanks guys
Ac

 

[damnyankee]

AC, it's in your email.  After 20 years of being on the net, I've found posting an image on this board has stumped me.  I ftp'ed to imageshack but can't get the link to work.  Thanks for posting it.

 

[abechap024]

Thanks DY I'll be able to double check my assumptions which is fantastic. I need to do that to the RMS and VCA circuit. Arska said that the circuits weren't right - but no answer so far on what is wrong with them? So I will send out the prototypes and then build one. Hopefully it works then I can order some PCBs and make them available.

 

[Biasrocks]

Arska said that the circuits weren't right - but no answer so far on what is wrong with them?

Look at the PDF's that Matthias posted here

http://www.groupdiy.com/index.php?topic=30006.msg494187#msg494187

Those schematics are drawn from actual dissected modules.

Mark

 

[damnyankee]

Hey Abe...

Matthias already dissected his 200 VCA & 209 RMS cans - he's even made the pcb boards ready for etching.  check out the links below...

http://www.cmaudio.net/forum/dbx%20model200%20vca%20module.pdf

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

If you have the main pcb done, then we're on our way.

By chance, does Eagle create a parts list as you created the pcb board?

DY

 

[abechap024]

Hi Guys,
thank you for the obvious - I knew they were there but didn't think to look at them again. I did and found that in the first left hand picture the Ca3083 unit is upside down. But we're still good. if those schematics are right (its of an actual model! so it should be- I can be a little faithless I guess)
So now its just double checking...everything
I'll send out a BOM and it needs to be checked against:

http://www.dbxpro.com/product_downloads/Calibration_Procedure/160-161%20Calibration%20Procedure.pdf

its more than likely that I typed a part in wrong. Also the parts #s are not going to match the original schematic, I don't for see this a problem as I'll have a nice new schematic one everything is double triple, and then checked again

 

[damnyankee]

YES!!!!!  Thank you, Abe!

As you've pretty much finished off the board, what are your thoughts for layout?  Since the pcb appear smaller than the original, do you think we could stuff (2) in a single, 19" rack or (4) in a double, 19" rack?  

And for the LEDs, could we use (2) of these stereo LEDs for the single, 19" rack: http://www.arcade-electronics.com/detail.aspx?ID=17695 in place of the VU meters.

And for the 3.5" tall, 19" rack with (4) units, we could use these: http://www.arcade-electronics.com/detail.aspx?ID=17696 in place of the VU meters.

Then for the rack/front panel, we'd have to ask purusha to do one up for us.

Thoughts???

DY

 

[arska]

Here is RMS208 tested schematics, original and modified.

 

[arska]

RMS208 modified

 

[arska]

More vca info, correct schematic for vca200

 

[arska]

Gain reduction meter, analog and ledbar version

 

[tmuikku]

Gain reduction meter, analog and ledbar version

The meter PDF seems to cut top of the schemo out...
Wow, alot of info pouring in

 

[damnyankee]

More vca info, correct schematic for vca200

I might be wrong, arska, but won't there be a need for some component changes on the main board if the swap is made for the 202 series VCAs???  

I have gold-canned 202's in my 903 compressors.  I can't find ANY documentation from dbx stating 202 VCAs were placed in the 117, 119, or 160VU...only silver & black canned 200 VCAs.

Your expertise would be most appreciated.

 

[arska]

There is vca200 and vca202 in the schematic file what I posted, theres no 202:s in the "oldies" .