SB4001 Support / Build Thread

[xjazzwreck]

guess i missed that.. thanks!

 

[canidoit]

If anyone accidently or forgets to pretrim the ratio trimpot, heres a thread that you might find useful in getting your unit back up to spec.
http://www.groupdiy.com/index.php?topic=944.0

Finished the build finally and calibrated!

 

[emrr]

I opted to cut pin 4 out of the socket itself for the two THAT2180C, rather than cut the IC's.  It is well elevated and can't touch anything. 

 

[mylesgm]

seem to have a problem with the ribbon cable mounting as when I put the boards side by side the ribbon connectors or too large and so the boards don't sit flush with each other. 

in the build description at the start of the thread you say:

"Plug in the ribbon cable before you mount the two boards together, you'll need to remove the strain relief from one end of the ribbon cable (either end, doesn't matter), otherwise it will nto fit."

but I don't know what this means, can you clarify or give a pic?

Thanks

 

[mulletchuck]

the piece of plastic that traps the ribbon so it folds back on itself.  remove that from one side.

 

[mylesgm]

ah. got it.

 

[SKJGProject]

hmmm i didn't remove any of them and it fits

 

[mylesgm]

Ok plugged it in and it fires up after a little late night stupidity...

Left channel seems to operate correctly as far as my initial tests go but the right hand side does not engage the compressor when the comp in button is depressed.  Left channel output alters exactly as expected but there is no change in the right hand audio and I would assume that this means that the relay is not operating correctly.  Any thoughts as to why that might be?  The relays are all seated and soldered correctly and I can't see any errors.

 

[ruckus328]

Ok plugged it in and it fires up after a little late night stupidity...

Left channel seems to operate correctly as far as my initial tests go but the right hand side does not engage the compressor when the comp in button is depressed.  Left channel output alters exactly as expected but there is no change in the right hand audio and I would assume that this means that the relay is not operating correctly.  Any thoughts as to why that might be?  The relays are all seated and soldered correctly and I can't see any errors.

Did you check that there's voltage at the relay coil when it's engaged?  That's step 1.  Report back, go from there.

 

[mylesgm]

working!  just reflowed the solder around the switch, relays and the ribbon cable, then reseated all opamps and now all is good.  now to attempt calibration without an extender set.  This might be fiddly.  Initial sound is pretty impressive already, smooth and punchy.

 

[gandhalf3]

I post here my issue with 2 on 3 of my SB4001 build.

After I backwarded the TL074 the 10r resistor blown up. As ruckus told me, i changed the 10r resistor and put some new TL074 and changed the 12v regulaotor.

Now the 10r don't blown up, but the Ratio seem to be backwarded (1.5 seems to compress much more than 10). and on one unit the right channel level is at -70dB than the other...

So should i changed everything ? (VCA, NE5534...)

Any idea ?

thanks

My 3rd unit works great !!!

 

[ruckus328]

I post here my issue with 2 on 3 of my SB4001 build.

After I backwarded the TL074 the 10r resistor blown up. As ruckus told me, i changed the 10r resistor and put some new TL074 and changed the 12v regulaotor.

Now the 10r don't blown up, but the Ratio seem to be backwarded (1.5 seems to compress much more than 10). and on one unit the right channel level is at -70dB than the other...

So should i changed everything ? (VCA, NE5534...)

Any idea ?

thanks

My 3rd unit works great !!!

Just to confirm, you replaced all TL074's and both the +12V and -12V regulators, correct?  Confirm you have +12V at TP201 and -12V at TP203.  TP202 is ground.

Do both units have the ratio issue?  Possible a blown diode in the rectifier/ratio section, result of the backwards TL074's, but honestly don't see this as likely.  Don't really see anything else that could've been damaged form the backwards TL074, there's nothing else there except the regulators, caps and resistors).  Caps should be fine, they're rated at 35V.  Could just be bad solder joint, something like that, would be my suspect, or maybe wrong resistor values installed.  Make sure the tantalum caps are not in backwards.  Honestly I'm really at a loss on this one, going to take some time to narrow it down.  Luckily you have a working unit that you can take measurements from if necessarry.

First thing I would do is this:  Send the unit a signal on the left channel only and compress.  See if the ratio issue is present.  Then repeat for the right channel and see if the ratio issue is still there.  This will help us determine if the issue is in the left or right sidechain, or after the summing point in the attack/release network.  At least this will help for me to give you an idea of which areas to inspect.

For the unit with the level problem, remove the audio VCA's (4 on each channel).  Be careful removing them, it's going to be tricky if you don't have an IC extractor tool.

Jumper Pins 1 & 8 on just one of the 4 VCA's (U2L for example) on the left channel, and do the same thing for the right channel (U2R).  The unit should now pass audio (you'll have 12db loss of gain, this is normal).  If the unit doesn't pass audio then the problem is in the audio section.  If it does pass audio then problem is in the sidechain.

Do all of this, report back.

 

[gandhalf3]

thanks a lot, that will be my next homework. I'm waiting the 51X proto board from silent art. This way i could measure voltage inside the unit.

 

[sonic02]

Hi ruckus, a question about the greyhills. I turned the shaft so the flat side faced left, inserted pins at 12 & 6 positions, I could then turn the switch 3 positions clockwise and then 5 positions counter cw, it then left the flat side of the shaft facing down, is this ok?

 

[emrr]

Finished, calibrated, all working.  Took my time, probably 20 hours total.  Did a test drive with various sources, comparing against some other comps.  Should be interesting to see where it fits in over time. 

Note on the build info; it's not fun to put the IC's in after it's fully assembled, the pics never show them in, and it never says where you choose to do so. 

Out of curiosity, is there any sort of PDF manual provided with the commercial pieces, that we DIY'ers might get for our files? 

 

[gandhalf3]

Hey its me again.

First thing I would do is this:  Send the unit a signal on the left channel only and compress.  See if the ratio issue is present.  Then repeat for the right channel and see if the ratio issue is still there.  This will help us determine if the issue is in the left or right sidechain, or after the summing point in the attack/release network.  At least this will help for me to give you an idea of which areas to inspect.

To follow that's what i can measure feeding the units with a 440 test tone. the levels are in Dbfs and can't be compared between the units because the Gain make up were not really at the same level. The Final calibration hasnt been done yet :

UNIT 1 (the one who seems to work well , and where the TL074 were not back warded):

Ratio	1,5	2	4	6	8	10
channel 1	-4,1	-5,8	-4,9	-5,4	-5	-4
channel 2	-4,1	-5,8	-4,9	-5,4	-5	-4

UNIT 2 : [/size]

Ratio	1,5	2	4	6	8	10
channel 1	-28	-74	-53	-74	-74	-53
channel 2	-4	-5,8	-5,6	-6,2	-6,1	-5,5

UNIT 3 : [/size]

Ratio	1,5	2	4	6	8	10
channel 1	-14,9	-4,4	-3,7	-4,2	-3,9	-3,2
channel 2	-2,8	-4,5	-3,8	-4,3	-4	-3,3

The 3rd unit hase a werd problem : when feed with a test tone, the ratio at 1.5, and when i unplug the channel 2, the channel 1 has a 12dB boost. this problem doesnt appear at others ratio.




I hope to check TP 202 and TP201 tomorrow.

 

[gandhalf3]

The voltage on TP201 and 203 :


+12,02 at 201  -14,81 at 203 for unit 1.
+12 at 201 et –11,89 at 203 for unit 2.
+11,84 at 201 –11,92 at 203 for unit 3.

 

[gandhalf3]

After calibration :

Unit 1 seems to work well.

Unit 2 is impossible to calibrate because of the 80dB drop on the Left channel when comp is in. (channel 1)

Unit 3 apart from the 1.5 ratio problem seems to work well. (A bad solder join on the ratio switch caused the problem )
(The ratio seems not the be always the same, depend on the threshold. I mean, at 1.5/1 ratio, and - 8dB of reduction,  4/1 reduce less than 2/1. And at -12dB they seem to work as they should......)

 

[xjazzwreck]

So I finally got around to finishing the SB4001! Beautiful unit and it powered up fine...

BUT!

Somehow I skipped the pretrimming of all trimpots. Duh, not sure how I missed that.

So I have desoldered VR4L/R & VR203 pretrimmer, and put back on the board (took forever...). Can I get the other trimpots calibrated without desoldering and pretrimming?

Thanks and sorry I have to ask such a stupid question.

Take care,
Keith

 

[ruckus328]

The voltage on TP201 and 203 :


+12,02 at 201  -14,81 at 203 for unit 1.
+12 at 201 et –11,89 at 203 for unit 2.
+11,84 at 201 –11,92 at 203 for unit 3.

-14 at TP203 is not correct, it means your -12V regulator isn't regulating - either isn't soldered correctly or is blown.  Unit may seem to work, but some things will be off.  Best to replace it.