MixBuzz500 build/support tHread

[bkbirge]

Anyone able to help? The sidechain filters and ratio knobs don't seem to behave as expected, at least if they do it is a lot more subtle than I expected, to the point I can't really hear it. The other stuff works, audio passes nice and clean, compresses nicely, attack/release work well, metering seems to work, each side is reasonably balanced.

 

[Igor]

Question about the bypass caps on the vca boards, the BOM says 220uf but that is different compared with the other boards' BOM, seems it should be 220pf ? Which is correct, thanks!

Also, any plans to finish up the crush & blend w/MS expansion?

Typo. The byp caps should be 47nF....0.22uF.

Ohho. It is drawn, layed out and waiting. One good day.

 

[Igor]

All built! Now I just need to calibrate. I've put 2180A's in the build, the pre-trimmed vca's, how does this change the calibration procedure, if at all? I do have all the trimmers installed, figured I'd do that in case I swapped out for 2181's at some point.

In case of use 2180 instead of 2181, throw these 50k trimmers out.

 

[Igor]

Anyone able to help? The sidechain filters and ratio knobs don't seem to behave as expected, at least if they do it is a lot more subtle than I expected, to the point I can't really hear it. The other stuff works, audio passes nice and clean, compresses nicely, attack/release work well, metering seems to work, each side is reasonably balanced.

Check for mistakes. I have same eyes, hands and mathematics as you, but have no your compressor at my workbench.
Feed 50 Hz, adj threshold for 20 db of compression w/o filters; GR should be less with filters.

Ratio:
http://www.groupdiy.com/index.php?action=post;msg=487554;topic=39459.0
(R60)

Test pro for MixBuzz1 can be applied to small bro predessor.
http://www.groupdiy.com/index.php?topic=41654.msg517391#msg517391

 

[bkbirge]

Thanks Igor I'll check that out. At this point everything seems to be working but not calibrated very well. The ratio switch performs different for each board, one side slight gain reduction on increasing ratio, the other side the opposite so I know it's a calibration issue. I will dump the 50k trimmer and see if that helps. Using it in mono so far sounds really nice, tames my upright bass resonances much more musically than my other gear, far more transparent sounding than what I remember from using the official SSL boxes years ago. I did blow a bank of 2180's at first somehow during my initial calibration, annoying. Gotta work on the steady hands when power applied. Thanks for a great project, I will post pics and clips when it is truly running to spec.

Anyone able to help? The sidechain filters and ratio knobs don't seem to behave as expected, at least if they do it is a lot more subtle than I expected, to the point I can't really hear it. The other stuff works, audio passes nice and clean, compresses nicely, attack/release work well, metering seems to work, each side is reasonably balanced.

Check for mistakes. I have same eyes, hands and mathematics as you, but have no your compressor at my workbench.
Feed 50 Hz, adj threshold for 20 db of compression w/o filters; GR should be less with filters.

Ratio:
http://www.groupdiy.com/index.php?action=post;msg=487554;topic=39459.0
(R60)

Test pro for MixBuzz1 can be applied to small bro predessor.
http://www.groupdiy.com/index.php?topic=41654.msg517391#msg517391

 

[Igor]

OK, cool than, calm my curiosity what was the issue when fixed!

 

[bkbirge]

Finally had some time away from the fam to work on this... took out the 50k trimmer since I'm using 2180's and set RV1 for 5.1k. Clumsy fingers effed something up, one channel is mega distorted now, and the 5532 on the vca gets too hot to touch, swapped it out for new and same thing. Other channel sounds wonderful. Looked for solder bridges, etc nothing found, so I'll start swapping ic's from the other channel.

 

[bkbirge]

All works great, latest and last issue was the 5532 on the vca board is actually supposed to be a 5534, lol duh. As usual my brain and sensory organs are conspiring against me daily. Anyway, this was my first 51x module build and a huge thanks to those of you that built it and documented before me, as well as to Igor of course for developing the project.

 

[Igor]

Great! Have a fun.

 

[rascalseven]

What is this resistor?  It's on the back of the front panel sub pcb.  Can't find a reference to it.

http://s251.photobucket.com/albums/gg291/diy33609/mixbuzz500/?action=view&current=P1040233.jpg

I'm about to assemble the populated pcb's now and check the thing out, and I'm not using a resistor here, so just making sure I'm not missing something.

Thanks!

JC

 

[Igor]

R60, ratios...
In this one, I got lower than should be ratios, and connected this resitor in parallel to R60 instead of replacing R60 to lower value.

 

[timmygrimm]

Hey All,

I got the test boards with my Mixbuzz... Where do I get the edge connectors for these?

Thanks!

Tim

 

[culteousness1]

See reply #237.

Volker's WM-thread

Cheers,
Carsten

 

[[silent:arts]]

I got the test boards with my Mixbuzz... Where do I get the edge connectors for these?

http://classicapi.com/catalog/index.php?cPath=84_86

 

[culteousness1]

Yes. Of course.

Didn't see his location...

 

[fazeka]

Hi Igor,

Have a problem with my MixBuzz500 build, similar to kibadachi:

http://www.groupdiy.com/index.php?topic=39459.msg532896#msg532896

On my build, audio passes through in standby and audio passes in 4000 and gssl mode. I think I can hear it compressing, but make up does not seem to increase level and other controls seemingly not working. Like kibadachi, I hear the relays when switching from bypass to 4k and gssl. Meter is not moving as well.

Then I looked at your post:

http://www.groupdiy.com/index.php?topic=39459.msg532916#msg532916

"First, let's check the voltage beween gnd and wiper of threshold pot, it should change from approx. +6.5 to -6.5 Volt when rotating the THRESHOLD pot."

But when I measure from outer lug of threshold pot to center lug 2 of same, I get ~-13.33 V to zero when rotating threshold. If I measure other outer lug to center lug, I get zero to ~+13.33 V while rotating.

Suspicious as ~13.33/2 = ~6.67, which is close to 6.5 as stated in post above (actually, range should be +/- 6.5 V).

Any ideas on troubleshooting?

Best,
Chris

 

[Harpo]

'...beween gnd and wiper of threshold pot...'
the pins at the pots outer lugs are not at gnd/0V, but your measurements look OK.
Double check resistor values, especially R55, R59, R60, R70, R74 and R75.

 

[fazeka]

'...beween gnd and wiper of threshold pot...'
the pins at the pots outer lugs are not at gnd/0V, but your measurements look OK.
Double check resistor values, especially R55, R59, R60, R70, R74 and R75.

Oops... :-[ ...feel stupid... Don't know why I thought that...

Let me check again.

 

[fazeka]

Hmmm...

Double-checked everything. Resistors, etc.

Regarding specifics to my build: R60 = 100R, R75 = 49R9

Voltages while sweeping threshold pot are still strange:

-7.01 to -6.93 on one leg
+6.39 to 6.46 on the other leg

Threshold pot bad, maybe?

 

[Harpo]

Voltages while sweeping threshold pot are still strange:
-7.01 to -6.93 on one leg
+6.39 to 6.46 on the other leg
Threshold pot bad, maybe?

No. Your pot seems close to perfect.
Your 50K law bending trimmer TR_TRM seems a little off center, loading down one side a little more or your 3K9 resistors R68+R76 are a little off their stated value.
Measuring threshold between wiper and 0V will give a +/-6.7415 VDC reading with all parts and +/-12 voltage rails being perfect (usually these come with tolerances).
Double check resistor values in the sidechain section again for the most likely reason of misbehaviour.