SB4000 Support Thread

[David R.]

Great, hope to see you at AES!  Do you have a booth?  I will look for you.

 

[romplex]

Hi, i just started doing the sb4000 project  , and im missing a 330PF ceramic capacitor @ c101, can i get any replacement or does it have to be a certain kind?

 

[Harpo]

Hi, i just started doing the sb4000 project  , and im missing a 330PF ceramic capacitor @ c101, can i get any replacement or does it have to be a certain kind?

Might not be needed at all. (LPF set for 48kHz in 1st. inverting 2.5dB gain stage of the VU-driver) Not a critical part and not in audio path. Any cap in range 100pF-330pF with 0.1" pin spacing will do, if this stage doubtfully should oscillate.

 

[fazeka]

Hi all,

Finished my build. Fired up on the second time (the first time I rushed to put in the 8-pin ICs, got some mixed up in my haste...  ???).

Sounds pretty damn good.  ;D

Thanks Mike for making this project a no-brainer.

Chris

Here are a few quick pics:

 

[ilvassa]

...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.

Thanks man. I have worked on Trident consoles, repaired and modified some channels, It still works apparently, so I do have some knowledge on op amps.
If I put an ic in the correct position there is no way to blow it unless there are some problems in the power section, which appear to work correctly if no load is applied. Power supply that has problems with just one ic (corret type and pinout, tested and working correctly) i'ts preatty strange, so I guess problems are in the power section..
My question is, does anybody had similar problems?

 

[fazeka]

See my post above, I mixed up the 8-pin ICs and after figuring out my error, put them in the correct sockets and now everything is working... so I agree that if they were in the wrong sockets but with the right orientation they will not blow (unless as you say there's a problem in the power supply).

 

[sage]

Hi there

i am having an issue with the trip pots for VR5-7-8-10 the 10k variable

I am pre-trimmed all the other pots but 3 of them don't get to 10k - they measure 9.1 and 8.9 when at the max turn

I have double checked the part number for the manufacture and they are supposed to be 10k but as I said onle 1 of the 4 provided in the kit get to 10k.

Can I still use them or shall I get other ones?

sage

 

[Harpo]

i am having an issue with the trip pots for VR5-7-8-10 the 10k variable
I am pre-trimmed all the other pots but 3 of them don't get to 10k - they measure 9.1 and 8.9 when at the max turn

funny counting: 'VR5-7-8-10 ',  'but 3 of them', 'measure 9.1 and 8.9'

I have double checked the part number for the manufacture and they are supposed to be 10k

so they are within specs (25% tolerance)

Can I still use them or shall I get other ones?

You can use them

 

[sage]

Thank you very appreciated -

sage

 

[sage]

HELP! Could anyone please tell me if this wiring diagram is correct?
I wanna be 100% sure before we proceed and from the info I gather on the Switch specs this is the way but I rather be safe than sorry...

sage

 

[sage]

OK I will reply to MYSELF with this info....

ON post #868 this has been answered and solved and here is the answer in the picture:

 

[sage]

Finally DONE ! WE will get to test it on Sunday after calibration with our buddy Gary over at Henson's cause we don't have the proper tools here - I will post a couple of pictures -

sage

 

[sage]

one more

 

[sage]

here it is

 

[sage]

I am having a problem with the VU Meter - I bought the Hairball Audio 1mA model 8027

the meter works but when i connect the lamp it just loads everything down...

I have 12 volts out of A from PCB and i have K ground -

We feel that the meter might be shorting inside cause even connecting one cable of the LED it loads down the whole system.
No matter if + or - so basically the meter works well but NO LIGHT !

Is there a possibility this migth be a bad meter or is there any suggestion on how to solve this issue?

sage

 

[gyancey]

Hello - first post on GroupDIY.  I just finished my SB4000 and it worked perfectly on the first try.  Thanks! 

One question though:  I'm using the Quad VCA's and I find that the multi-turn pots have very little effect on the THD except on the extreme far end of one side of the adjustment.  Why use a pot with so many turns?  Am I missing something?

 

[Bo.b]

Hi all,

I need a bit of help please. I'm most definitely a noob, but I've got a dozen or so quite complex builds under my belt, I'm pretty meticulous. I've read through everything and checked everything but can't figure this one out. It's probably something simple - more than likely some dumb slip up - but I'm stumped.

I've got Quad VCA's with all vca's 2181b's. All components as per the Quad VCA xls bom.

I finished hooking everything up yesterday. All clean and solid in terms of wiring. All front panel controls seem to be working correctly.

I'm having trouble with step two of the calibration(!). I can't get less than a 6db(on DAW meter) jump LOUDER when the compressor is switched in. 0.35v jumps to 0.80v across pins 2&3 of my output xlr!

It seems like the kind of thing which upping the the unity gain VR's on the board(VR1 & VR2) would solve as I'm running out of turn to get the level low enough, but I don't think that's the proper way to do this, and my gut tells me that this issue denotes a mistake elsewhere.

My power rails at the main board are reading:

-15.14
-11.92
11.87
14.91

isolated 12v: 11.87

I don't have VR's on the psu board - should I swap out the fixed resistors for variable resistors and trim my voltages to clean +/-15 & +/-12? Could this be the source of the unity gain issue?

Unit has been powered on for hours, nothing had smoked and nothing feels hot to touch - though I haven't touched anything on the PSU board!!

Any help would be massively appreciated. Thanks,

Rob

EDIT: I never populated r77, r83, r121, r125 on the back side of the main board. Should these be populated, if so what with? Main BOM says 1k for r77 & r121, 120R for r83 & r125. Might this be the issue?

EDIT 2: Populated r77, r83, r121, r125... seems to be behaving better, but still got a discrepancy. I'm starting to wonder about those vr1 & vr2 trimmers...

EDIT 3: Ok... tail-between-the-legs moment. I installed the resistors as per above(edit1) on the backside of the board.
I also swapped VR1 & VR2 out for 50k pots which allowed me to set unity gain correctly
I also jumped R169 - the 47k resistor which gives the threshold a lot more throw. All calibrated and working fine.
Earlier today I'd had trouble also getting the THAT chips to seat in the sockets. I widened them with a trimmed off capacitor leg and a pair of pliers.

I was considering deleting this whole post to myself, but figured it might help someone coming across the same stuff.

COMPRESSOR NOW WORKING 100% AND SOUNDS BRILLIANT! DOES EXACTLY WHAT IT SAYS ON THE BOX. THANKS MIKE

 

[romplex]

Hi guys, ok ive finnaly gotten to the stage of wiring this thing up, im gonna order some wire online but i need an idea as to what types to get as there are so many, like gauge size and so on, if some one could  give me a rough idea would be fantastic

 

[druu]

For the usual hookup cable, I normally just buy some 6-core security cable (stuff used in home alarm systems) from your local electronics store.

 

[ruckus328]

Is there a possibility this migth be a bad meter or is there any suggestion on how to solve this issue?

Possibly.  R142 is current limiting resistor for meter backlight, what value resistor do you have here?  Sounds like you have a dead short from your description.