SB4000 Support Thread

[wave]

You might have to bite the bullet and get a meter that can test for the small value capacitance.
I've noticed more and more that a nice capacitance meter is pretty crucial for doing most projects.

Dave

 

[imo]

Agreed on the cap tester. I replaced the 100p on the right side and am getting a balanced load on the right output.
The tilt section is still a mystery however. I am only able to get about 1/2 the voltage i need to get the right reading for the calibration procedure.
Coming out of U2A the voltage is fine, and I am getting correct voltage at the Tilt 2 calibration spot, it is right around the U7A where its iffy. ANy ideas would be quite welcome! I can't seem to run it down

 

[imo]

OK, cap checker will be had.
Success! GOt the T1 circuit going with subbing in new 22pF caps. All is groovy! Thanks to Ruckus for the PCB and well detailed build docs.
Curious on a couple of things
1. Any comments on the quad VCA board verses the standard layout?
2. Anyone want to explain how the tilt circuit works? I stared at that part of the schematic for much too long and can't get a grasp on it
Thanks
Ian

 

[sr1200]

how it works electronically or how it works practically.  For the latter, there have been a couple of brief descriptions and explanations of this wonderful little option.  Best way to describe it is to hear it in action.  Take a drum bus (whole kit) and pop the 4000 on it.  set it to compress pretty heavily with the tilt OFF.  Then switch it over to T2.... notice the change in the way the comp handles the high end.

 

[jonathanmorbin]

Hi,

I wander if anyone can shed any light.

I built this compressor, it all functions correctly and is calibrated correctly. Sounds great by the way! best and easiest build ive done so far.

However i cannot get the bargraph to show the correct levels. When im using it it is always in the red. When i try to calibrate it i cant turn the variable resistors down any more to show the correct value. I come out of my DAW at -12 1khz and the lowest i can get on my input meter is 0. when i turn the level down the bargraph does go down all the way to the bottom but its just the values are not correct with my daw.

My only thought really is to change the TL074?

I presume other people have been able to get this calibrated fairly accuratley?

 

[pablobolche]

I just finished my sb4000 build and same as jonathanmorbin.. the bargraph is way too hot although it seems pretty clos to the marks on the faceplate... Seems to me the the issue has to do with r167 and r157.. these set the reference level for the led meter.. although I don't get the maths behind this yet .. there is a note on the schematic - led meter section.. might want to chek it out..
I am going to try some different values for these to see how they relate and try to work it out..

great project.. I am truely greatful to have this compressor in my hands now...after a year of looking at the kit and kind of scared..
thanks

 

[sr1200]

Keep in mind your daw is full scale and the meter on the SB is NOT, so -12 on your DAW should read about 0 on the SB.

 

[Statherian]

Hello

just started my build with the kit from Serpent, right now im at the resistor stage, got some noob issues hehe

The R76 and R96 say 680k on the board (there was no 680k in the kit)
but on the BOM list it says that there should be 220k in R76 and R96 ( i got two of those left)

got two big resistors on at 10R for the power PCB
but the other one 100R at R163 (stand vertically on board) where is this?

in the kit there was two 1.33K but nowhere to place them?!
also missing a 91k but thats not important, can but that in a store here.
and most of my 1k resistors are at 0.760 isnt that a bit low?

Thanks for all the help!

 

[druu]

Sounds like you might need to replace the battery in your multimeter. Or you've been given the wrong values for those.

 

[dryman]

Hello

just started my build with the kit from Serpent, right now im at the resistor stage, got some noob issues hehe

The R76 and R96 say 680k on the board (there was no 680k in the kit)
but on the BOM list it says that there should be 220k in R76 and R96 ( i got two of those left)

Schematics say 680k, so i think it should be correct. For QuadVCA it has to be a quarter of that.

got two big resistors on at 10R for the power PCB
but the other one 100R at R163 (stand vertically on board) where is this?

It is near the VU-Meter on the controlboard.

in the kit there was two 1.33K but nowhere to place them?!

they can be used in the powersupply instead of the 2k-pots to adjust the voltage.

also missing a 91k but thats not important, can but that in a store here.
and most of my 1k resistors are at 0.760 isnt that a bit low?

Yes, that is much to low. I am using 1% resistors, 1% is 10R

 

[seva]

Hi,

I have the same Problem like mica on Page 45 with the smoked resistor on psu.

All Vortages are correct if the Main Board is Not connected. When i connect the psu to the maiboard there is smoke at the psu near the Big resistor.

I disconnected And tested again. Everything is Fine with the psu.

There are no Ic,s And Vca,s populated on Main Board yet because i dont want damage theese. Could this the Problem be.

I dont understand because everything is Double checked And Looks right.

Greetings

Seva

 

[ruckus328]

Hi,

I have the same Problem like mica on Page 45 with the smoked resistor on psu.

All Vortages are correct if the Main Board is Not connected. When i connect the psu to the maiboard there is smoke at the psu near the Big resistor.

I disconnected And tested again. Everything is Fine with the psu.

There are no Ic,s And Vca,s populated on Main Board yet because i dont want damage theese. Could this the Problem be.

I dont understand because everything is Double checked And Looks right.

Greetings

Seva

If you mean R184 (10R) then you have something shorted or wired wrong on the +12V_ISO rail, causing U24 to draw too much current and blow the resistor.  +12V_ISO powers all of the relays, LED's, & bargraph section (On the control board it's referred to as +12V_VU).  Look on schematic for the specific reference designators in question, therein lies your problem.

 

[ruckus328]

Sounds like you might need to replace the battery in your multimeter. Or you've been given the wrong values for those.

Second this notion.... there are no 0.760K resistors here that could have been sent

 

[ruckus328]

Hi,

I wander if anyone can shed any light.

I built this compressor, it all functions correctly and is calibrated correctly. Sounds great by the way! best and easiest build ive done so far.

However i cannot get the bargraph to show the correct levels. When im using it it is always in the red. When i try to calibrate it i cant turn the variable resistors down any more to show the correct value. I come out of my DAW at -12 1khz and the lowest i can get on my input meter is 0. when i turn the level down the bargraph does go down all the way to the bottom but its just the values are not correct with my daw.

My only thought really is to change the TL074?

I presume other people have been able to get this calibrated fairly accuratley?

Welcome to the analog world

Like SR1200 mentioned, 0 in your daw has nothing to do with 0 in the analog world.  0 on the bargraph is 0VU.  0VU = +4dbu = 1.223V RMS.  0 in your daw is 0dbfs.  dbfs has no direct correlation to anything in analog as there is no standard.  A "general" rule of thumb though is 0dbu will usually translate to somewhere between -15dbfs to -19dbfs in your daw, depending on your converters.

 

[Statherian]

hey ruckus!

in the kit there was no 680k resistors, is this right?
can i use the two 220k resistors on r76 and r96?

um and i cant seem to get the THAT`s in the sockets, wont fit...

and no CAP, 10uF, 50V, 20%, ALUMINUM ELECTROLYTIC, LOW ESR

thanks in advance


My first build ever, down there, pretty cool! only thing ive done in the past is soldering XLR and EDAC stuff.

 

[seva]

Thanks a Lot ruckus.

I Shorted a wire to the Control Board while it was Not connected to the mainboard.

Now everything is Fine. So i starting the calibration.

Have someone experience with Film caps in the Audio path for couloration???

Which parts is ssl using in the original Bus comp in the console?

Greetings

 

[imo]

My board has been running great, sounds great!
Still having a minor problem with the bargraph. I am getting more level reported on the left side then the right when the whole unit is calibrated. I am doing the cailibration balanced instead of to ground as per the instructions. If i do it to ground then the meter is balanced but my signal is unblanced into my DAW. Any thoughts?

 

[ilvassa]

Hi, I have a problem with power supply, r182 and r183 gets hot and I don't get the correct voltages. I read of a similar problem, due to a reversed ic.
In my case I have problems in 15v rails as soon as I put in yust one ic, no matter in what position, nor what tipe of ic I do put in.
Anyone have some suggestion? Where should i search for some problems/mistakes?

 

[Harpo]

...as soon as I put in yust one ic, no matter in what position, nor what tipe of ic I do put in.

Expect every opamp you tried in a wrong socket or with reversed orientation to be blown.
For usual there is no 2nd chance after powering on with parts fitted wrong.
You have to put the correct opamp in its correct position with its correct parts orientation.
In this build you have 3 different types of opamps comming in a DIL8 housing, - single bipolar NE5534, dual bipolar NE5532 and dual JFET TL072 - and the chips pinout and function is not interchangable.

 

[whomper]

Hi,

After several good months of trying to debug my SB4000 on and off, I asked my good friend Igor Kapelevich to have a look.

Sure thing, after quick debugging time, the culprit was found!

On the control board board, all tantalum caps do not have a trace between the outer and center holes. As I connected all caps with the two outer holes, there was not cap connected back to the main board part of the release section for every release step.

This created the heavy distortion I was getting on the outputs.

Not sure whether there are several board revisions, but I would advise people that are building the board to inspect the control board caps for this issue.

Have enclosed a picture of Igor's trace modification.

Thanks Igor! I couldn't have done it without you