SB4000 Support Thread

[daal]

For the ext IN let me put my question more simply. Regardless of the face lettering, when electrical contact is made by the switch, should we be in EXT in mode or in In mode ? That's what I was never sure of

Ok so here is where I am after fixing the ribbon cable :
- All knobs seem to work.
- I was able to pass step 3 correctly.
- The bargraph still shows no life at all ...

 

[wave]

When the switch is closed ext in is engaged.

Dave

 

[daal]

Ok thanks, so I indeed did put it backward

Everything looks good, LED working, silly silly me, I did put the bargraph backward  ??? I spent 5 minutes when mounting to find its pin 1 and didn't find it so I assumed it can go either way ... BUT this mistake make me see I didn't put JMP7 neither, so I did that at the same time.

Will finish the calibration... A big thanks to Mike for the amazing job !!! Very nice kit !!

 

[sr1200]

Speaking of Mike, has anyone hear from him recently?  Emails to his site are going unanswered.  I saw his ad for the 4001 in tape op in the last issue, wanted to let him know.

 

[daal]

sr1200, only thing I know I ordered my kit 3 weeks ago and it was posted in 48hr, so he must be somewhere

Wow Everything works fine !!!! It's very impressive on drums with T2 setting !!

Even the sidechain send / return seems to work great ! Just some finish and that will be my default mixbus beast

On the blog side, everything is up to date :

http://stereodramadiy.blogspot.fr/2012/07/sb4000-quad-vca-recap-post.html

I made a SB4000 Quad VCA Google Docs BOM with everything I needed exactly for my build (the 2 original BOMs are compiled and I added some details like sockets/pins for mounting quad boards, I used same reference as bandmaster, thanks to him)

Here it is : SB4000 Quad VCA BOM

More infos in this post : SB4000 Quad VCA BOM related blog post

 

[band_master]

hey guys,
I have an extra par-metal case for this project i don't need. if anyone is interested send me a PM. thanks!

BD

 

[dryman]

Today i fire up the power-supply of my new build SB4000. +/-15V is OK, +12V is also OK. But instead of -12V i get -20V. I try three different VRs, but no one show me the -12V, everytime i get -20V. The input-voltage of the regulator is 28V. Should i change the 2*18V Transformer to an 2*15V type?
I read in the thread, that there are problems with 7912 from STM. Two of the VRs i tried, were from STM (L7912CV), but one was an old used one.

-12V needs a load. After i connect a load, -12V are OK. SB4000 is running now and sounds good.

 

[whomper]

Hi,

Getting back to debugging my unit after several months pf focusing on other projects.

My problem is still in place, unfortunately:

Am getting distortion on compression. Unit is on, signal is great. As soon as I move the threshold pot and the meter starts to show gain reduction, distortion is added to the sound. I traced it to the two TL074 in the side chain section. Pin14 for example produces the distortion signal (on a 1K sine wave input, TL074 pin 14 produces sine at 2K, 4K, 8K in decreasing levels) which is then added to the main signal.

What could cause the side chain to create that distortion? The signal is reduced in volume as it should, but harmonic distortion is added to the  signal.

Everything else worked. All power rails are as they should, calibration procedure executed to its fullest and this is the only thing left :-(

 

[sr1200]

quick question for anyone thats built the unit and a send n blend.  Is it possible to fit the send n blend in the case with the SB board (obviously have to get a longer case) But a buddy of mine is interested in gettin a 4000+SNB and taking the ext in switch out and putting in a SNB mix pot.

 

[sr1200]

Mike, if youre still readin this thread... placed the order for the SNB and another 4000 this past week. Would like to know if its possible to throw a mod in to add a 20:1 ratio on this bad boy.

 

[kml23956]

I too would like hear from him about my purchase from his website over a week ago. So far no response to emails.

 

[kepeb]

...
Maybe in the sales/shipping thread would be better?


started on this a few weeks back, looked through the thread and files and most questions have been addressed.

has anyone made an FPD file with the front panel text/layout etc. ?

 

[sr1200]

Spoke to mike last night, Hes having some back issues again and said that orders should be getting shipped out in the next couple days.

 

[kepeb]

DUDE?!

And guys, don't wanna sound like a crotchidy crotch but friendly request, PLEASE refer all purchasing/kit questions to the white market.  Do not post these questions here, this thread is BUILD SUPPORT.  Otherwise this thread becomes useless and we end we'll end up with a 100 pages with only 1 actual page of useful build information, and the same questions just keep getting asked over and over because nobody can find the answers.

Anyway. until i decide how to finish the panel,
I made a start on one (attached- rename to .fpd) so I can just use decals.
you will want to add the bargraph if you use it

edit/print a rough one and line it up how you want etc.
but the switch positions should be right.

It would be nice to see some proper ones, I have no idea what i'm doing with fpd!!

 

[whomper]

Am getting distortion on compression. Unit is on, signal is great. As soon as I move the threshold pot and the meter starts to show gain reduction, distortion is added to the sound. I traced it to the two TL074 in the side chain section. Pin14 for example produces the distortion signal (on a 1K sine wave input, TL074 pin 14 produces sine at 2K, 4K, 8K in decreasing levels) which is then added to the main signal.

Perhaps someone can post TL074 voltages or even frequency screenshots for for a sine wave with some DB of reduction on the output (10db?). Comparing with a working unit while compressing might shed some light on the matter.

 

[sr1200]

kepeb i thought ruck posted a FPD on the first page.  Only thing is it doesnt have any markings (silk screen or engraved).

 

[imo]

Hello,
I have an up and running SB4000, sounds great! All calibration has gone smooth, bar for the T1 calibration. I cannot get the meter to reflect 10db compression within the trimpots span. I have checked all components(R46, R40, VR5, R3, R4. R7, C47, C53, C82, C11, C15, C28, C36) I replaced the 5532, checked for solder bridges, reflowed solder on all components.
I can get the T1 to reflect at most 5db when all other positions reflect 10db. At this setting TP11 is about .979Vac(TP12 goes from around 1.5Vac-3Vac depending on trimpot position). T2 is around 2.65Vac, which seems right, and the second Tilt function works correctly.
My DAW is showing even output levels on Left and Right, but the bargraph meter shows uneven output level between Left and right. Are these 2 issues related? Any ideas on obvious problems or places to look further?
Thanks
Ian

 

[imo]

doing some poking around the output stage. It seems that that on my right channel all of the signal is going to hot(pin2), whereas on the left the signal is equally split(balanced). I have tried replacing the 5532 in the right channel. I have also measured all of the resistors in both left and right, and everything seems to measure out. Both channel VCA's are spitting out the same signal level, so it must be in that 1st 5532 stage. All the 10k's measure out correctly. What else could be causing the 1 5532 to not be rebalancing the signal? Possibly a bad comp cap(100p)? they are all marked right(100p), but i have no way to measure caps that small
thanks
Ian

 

[sr1200]

There should be markings on the cap that tell you the value (albeit in code)

 

[imo]

yes, the caps are correctly marked at 100p. I should have been more specific. It is possible that one of them is bad or out of spec, but it would have to be pretty significant to change the AC voltage at stage 1 of the 5532. Just trying to figure out what could be happening other than that with the 1st stage to change the voltage