dbx 160vu clone

[bovox]

Hey , when can we expect those new badges of pcb;s?
Cheers Bo

 

[abechap024]

Yes, anyone with a real dbx 160vu would be much loved if they could compress the files I uploaded so we could hear what a real unit sounds like on this material.

At this point even if it sounded completely off I still find this version very useful. I think they will sound pretty close though.

Or alternatively someone could compress some stuff with their "real" 160vu  unit and then send the uncompressed stuff to me (along with some settings) and I willl be happy to compress it this weekend.

Also if you look at the files it looks like the RMS detector is compressing one side of the waveform more than the other. I think Im beginning to understand the calibration document a bet better. We set r36 so a symmetrical 100hz wave form is observed on the comp pin. That way the rms unit sends info to vca of a symmetrical waveform. So this weekend I'm going to mess with that a bit...also for 2nd rev I put a trim pot in there so we don't need to try to mess with a resistor sub box.

Also next batch of PCBs are almost ready. Look for that other thread .

Abe

 

[tomcat]

Dont like to fill up the order thread

Did you do a comparsion between discrete and Thats21xx on the dbx?

 

[abechap024]

I found some files online of a authentic 160vu compressing and the plain files; so this weekend I'll compress them so we can compare!


Also the meter circuit is working fine! I overlooked that the meter is on a different scale. -40 to +20 BAHAH! I was trying to get the meter to match my VU meters in my console! hahah no wonder it would match up at zero then seem to stick around the middle. just goes to show sometimes problems aren't even problems.

So options:
I'm talking to Mike from Hairball if he can get some made up with correct scale, otherwise I'm going to see how hard it is to take my hairball meter apart and put in correct scale :
http://www.cmaudio.de/forum/160scale.jpg

 

[haima]

Good news on all fronts! Thanks AC! If only I could find some time to put my rev1 proto together... 

 

[abechap024]

Some more Good News. Hairball is going to stock the Correct meters for our DBX build. That is great news.

 

[dandeurloo]

my case isn't far behind either.  Abe already confirmed that everything fits now I am just getting the front panel silkscreened and they should be good to go.  Hopefully next week I will have that back!

 

[damnyankee]

Wait until you guys see the front panel...!  KILLER!!!

 

[Neil]

One of these is definitely on my build list. So Rev 2 should be a pretty painless build? Sounds like things have really come together!

 

[haima]

In case anyone wants one, there's one on ebay:

http://cgi.ebay.com/RARE-ORIGINAL-dbx-VU-Compressor-Limiter-Beede-Meter-/280620195591?pt=LH_DefaultDomain_0&hash=item4156445f07

Probably best to leave it to someone with a broken original unit!

 

[damnyankee]

One of these is definitely on my build list. So Rev 2 should be a pretty painless build? Sounds like things have really come together!

Abe emailed me and said he used it in a session (vocals) and he said it sounded great!  He said it smoothed the vocal out just right and added a nice chunkiness. 

I'm still piddling around troubleshooting my power supply (trafo, actually).  With some luck, I'll have a working power supply this evening and tomorrow evening, a functional unit.  This is my first build of this magnitude and I'm am learning so much!  It's alot more complex than 9V battery powered geetar pedals, lemme tell ya! 

DY

 

[damnyankee]

Guys,

I'm having a difficult time wiring this torroidal up for our board: http://www.antekinc.com/pdf/AN-0225.pdf

I have two of these and we're blowing fuses like candy.

I'm wiring red/red to Neutral on the IEC socket.  Black to black to Live/Hot on the IEC socket.

I check resistance to ensure I have the correct pair of blue/green combos and check for each pair for voltage (each pair gives me 26V):
One pair goes to the outside pins of AC In molex pins, correct?
The other pair is for centertap, correct?

The problem is, when I wire the other pair for the centertap, the fuse blows.  The fuse blows regardless if the centertap is or isn't installed in the center molex pin (ground) connector.

What am I doing wrong?

Thanks in advance,

DY

 

[Rob Flinn]

The centre tap should be a blue & green pair, the other blue & green should go one each to the other 2 psu inputs.

 

[damnyankee]

The centre tap should be a blue & green pair, the other blue & green should go one each to the other 2 psu inputs.

That's what I'm doing.  And I'm blowing fuses.  With both trafos.

Now get this: if I desolder both red and black primaries and resolder only one red and one black to the IEC socket then insert the "other blue & green" to the 2 psu inputs (no centertap), I get voltage on the pcb: +/-23V and +/-9.6V (I need +/-15V).  While this combination gives me power to the board, I measured the voltages across each diode in the diode bridge (D16, D13, D14, D15) and they run about 15V.  I follow the trace to C36 (first filter cap) and it measures 9.6V; the second filter cap measures -23V.  Thinking C36 was bad, I replaced it with another cap and I get the same 9.6V.  All solder connections have been triple checked and there are no shorts.

So I hook both red and black primaries back up, put the blue & green pair to the 2 psu inputs (no centertap), fire it up and POOF! goes another fuse.  I hook the centertap pair together, fire it up and POOF! goes another fuse.

With both primaries, blue & green pair to the 2 psu inputs and the centertap pair together in the center psu input (ground), fire it up and and POOF! goes another fuse.

Four nights and 20 fuses later, I can't figure this out.  It's maddening!  ANY suggestions would be most welcome!

Thank you in advance,

DY

 

[Rob Flinn]

If you live in the states then you should connect the primary taps in parallel.  i.e 2 blacks together & 2 reds together. Connect the blacks to 1 pole of your i.e.c mains socket, & the reds to the other.

I don't have a 160vu board but because there are so many op amps it must need a bipolar psu.  Normally your mains transformer secondary will have 3 connections.  Looking at the pic of the board overlay they are marked A  G & A.  Connect a blue & green pair to G, & the other blue & green connect individually 1 each to on of the A's.

Also I would check that you have the diodes orientated correctly, if they are wrong you may be creating a direct(ish) path across the transformer secondary.

 

[damnyankee]

Hi Rob,

If you live in the states then you should connect the primary taps in parallel.  i.e 2 blacks together & 2 reds together. Connect the blacks to 1 pole of your i.e.c mains socket, & the reds to the other.

Check.  Both Black primaries are going to L(ive), both Red primaries are going to N(eutral) on the back of the IEC socket.

I don't have a 160vu board but because there are so many op amps it must need a bipolar psu.   Normally your mains transformer secondary will have 3 connections.  Looking at the pic of the board overlay they are marked A  G & A.  Connect a blue & green pair to G, & the other blue & green connect individually 1 each to on of the A's.

Check. To ensure I had the correct pairing of blue & green, I did a resistance test: DMM set to 200 ohms, one clip to blue, the other clip to green.  If I can measure resistance between the two leads, then the blue & green is paired up.  One blue goes to "A", the corresponding green goes to "A" on the other pin.  The other pair are wired together to create the center tap.  I still pop fuses when both Red primaries and both Black primaries are soldered to the IEC socket with the blue to green lead wired together to create center tap (and I haven't inserted the centertap to the middle pin "G" yet!).

Also I would check that you have the diodes orientated correctly, if they are wrong you may be creating a direct(ish) path across the transformer secondary.

I have checked the diodes and they are orientated correctly.  The issue is, I pop fuses BEFORE inserting the centertap to the "G" pin on the board.  This has to be something simple - and thank you for your valued advice, Rob!

DY

 

[Rob Flinn]

when you connect a green & blue together for the centre tap, make sure they are not both on the same winding.  They should be from different secondary windings.  If they're not you are shorting one of the windings.... a definite fuse popper.....

 

[damnyankee]

when you connect a green & blue together for the centre tap, make sure they are not both on the same winding.  They should be from different secondary windings.   If they're not you are shorting one of the windings.... a definite fuse popper.....

So here's my question (I'm a simple man with a simple mind):

The secondary leads are Blue A, Blue B, Green A, Green B (I'm just giving them a label as I don't know which winding they are in).

1. I test for resistance for Blue A and Green B.  The ohm reading on my DMM is "1" (not 1 ohm but as in no ohm measurement.

2. I test for resistance for Blue A and Green A.  The ohm reading on my DMM is actually 3.8 to 4 ohms.

So I would use Blue A and Green A for the power supply and Blue B and Green B for the centertap, correct?

DY

 

[j.frad]

We have original 160VUs here, if you have drums, basses and vocals, I can run them through.
The behaviour is most noticable on kick, snare, voices.
jules.

 

[Rob Flinn]

use Green A & Blue B for the centre tap & connect to the middle pin marked G on the board, & the other green B & blue A indiviudally to the points marked A on the board either side of the point marked G