MixBuzz500 build/support tHread

[mnats]

Thanks Igor - Works great!

I've posted some notes here: http://mnats.net/mixbuzz_500_build.html

 

[reanimatorstudio]

Congrats mnats!! Your notes are really great too. I'm going to put a link in my "How to build a Mixbuzz 500 step by step" if you don't mind :http://www.groupdiy.com/index.php?topic=40493.msg553174#msg553174



I need some help with the SYM trimmers. I have no distortion meter so I used the method Igor suggested 0 volts on the output pins of IC 11 (opa2604). The thing is that it is constant drifting. In the beginning much more and after 30 minutes some millivolts. The other thing is that the trimmers are at there end position and I'm using 4x 2181A's on the VCA boards and also 2181A in the sidechain. (It was cheaper to order 10 x 2181 of the same model)


Is there some freeware distortion meter?

Do I leave out R33 and SC_SYM and forget the DC on pin 1  of IC11?

Is there another way?

 

[noulou]

brilliant kit as usual, thanks Igor!

 

[wowi]

One more 500 Mixbus ready here, but ... a little bug has survived:

The left channel has 3db more output than the right. This occurs, even if the threshold is turned up, so that there is no compression.
When i go on bypass, everything is ok. Both channels compress and sound as they should.

Any idea where to look ?

Wolfgang

 

[Igor]

Which VCA's used?
Wrong resistor in audio path, maybe... Wrong resistor at VCA PCB...
Or, 5534 at VCA PCB has too much offset....almost impossible.
Other-vice, IF the CV at one side was not correct... But the control voltages are tied together.
As usual, CHECK EVERY PART, and you'll find the mistake.

@Mnats: awesome!!!! I just reading
http://mnats.net/mixbuzz_500_build.html.
Man, I have to learn from you how to give REAL build support!!!!
I wish to have bit more time, as well))

 

[Marcocet]

Okay, here's where I'm at

I finished putting the unit together. It powers up, and I can hear the relays clicking as I go in and out of bypass. The meter is showing gain reduction as I turn the threshold knob. However the audio doesn't seem to be effected at all, and the make up gain doesn't change the output either.

Any thoughts? I can't seem to track it down... Thanks

 

[culteousness1]

Is there some freeware distortion meter?

You may check RightMark Audio Analyzer:

http://audio.rightmark.org/index_new.shtml

It's abled to measure the Total Harmonic Distortion and there is a free version.

Cheers,
Carsten

 

[Igor]

Strange... Did you connected the power supply of small (control) pcb?

 

[Marcocet]

Yes. The bypass LED is functioning perfectly, and the meter appears to be showing gain reduction although the output is not being effected. I can hear the relays clicking when I flick the bypass so I assume that's not the issue. Any other thoughts?

I'll take some pictures when I get a chance to put my hands on it again. Thanks

 

[Igor]

Great. Let's check:

When turning MAKEUP and THRESHOLD pots, at the pin 7 and 8 of IC7b the voltage should change within range of couple of volts,
(without getting deep into precision mathematic)

If yes, check resistors R60=100r, R75=49r next.
Than, go to audio board and check if there's voltage change when rotating the trimpots at CTL connector, pins 1 and 3
(or, check at R100, R45). Check R100=909R. Maybe, bad contact at pin 1 of CTL connector.
If this does not helps, check on VCA adaptor PCB: R101=732R, R102=100r, check if IC9 (NE5534) installed correct as well.

 

[Marcocet]

Found it. I'd done the calculations for R100 right (using a 202C) but somehow put the wrong value in! The makeup not working was just a bad contact.

It's totally awesome. Thanks for all the help and for your hard work Igor.

 

[Igor]

Cool, enjoy!

 

[timmygrimm]

I'm trying to put together Mouser part numbers for everything.

https://www.mouser.com:443/ProjectManager/ProjectDetail.aspx?AccessID=d986302f5e

I think I got everything with the following exceptions:

- 6.8uf audio grade caps (C38) arent available through Mouser. Don't know if I can sub in a value or just find a different source.

- Mouser seems to have no 5mm LEDs...

- I'm not sure what to order for the PCB INTERCONNECT SOCKET/RAW CONNECTORS.

- Got the 10 pin male headers, but couldn't find any female sockets with horizontal wire mount like I see in people's photos. I put this http://www.mouser.com/Search/ProductDetail.aspx?R=M80-8881005virtualkey57420000virtualkey855-M80-8881005 in the project, but not sure if it will fit / work.

- I put these ferrite beads on the order but not sure if they will fit. http://www.mouser.com/Search/ProductDetail.aspx?R=4212-2virtualkey51820000virtualkey807-4212-2

- I ordered 2181A(s) as per BOM, but others say 2180A is best choice? Confused...

- Not sure which 10 connector wire to order (gauge, etc). Options here: http://www.mouser.com/Wire-Cable/Flat-Cable/_/N-5ggm?P=1z0vl9dZ1z0vt0b


If people wouldn't mind double checking my work... I spent quite a bit of time trying to get things right (cross-referencing Farnell parts), but I have have had some completely unusable parts show up on my doorstep before, so any help would be greatly appreciated and hopefully other US people can benefit from this. Tried to put Igors ref #s on things, but alas some are missing.

Best,

Tim

 

[Igor]

Hi, I am not very familiar with Mouser, BTW, scroll this thread, there was an alternative BOM with all p/nr's from Digikey or Mouser IIRC.
Will try to help...

- 6.8uf audio grade caps (C38)

Tantalum, 16-25V

- Mouser seems to have no 5mm LEDs...

No way

- I'm not sure what to order for the PCB INTERCONNECT SOCKET/RAW CONNECTORS.

Check Farnell 7991967 and  1022262 ; Mouser should have similar products.

- I ordered 2181A(s) as per BOM, but others say 2180A is best choice? Confused...

Others, aye!

2181A will work absolutely fine. 2180 is pre-trimmed, the only difference

10 pin male headers,

HEADER, STRAIGHT, 10WAY

http://il.farnell.com/avx-interconnect/008380010000010/header-straight-10way/dp/636332?Ntt=636332

- Not sure which 10 connector wire to order (gauge, etc).

Socket, IDC, 10 way

http://il.farnell.com/avx-interconnect/008290010000011/socket-idc-10way/dp/636034?Ntt=636034

Hope this helps.

 

[timmygrimm]

Thanks Igor!

I scrolled through the whole thread again and didn't see an alternative BOM, but I looked through your suggestions and think I have everything covered.

https://www.mouser.com:443/ProjectManager/ProjectDetail.aspx?AccessID=d986302f5e

I'm wondering if cut dip-16 sockets will work for the 2181s since the spacing is pretty tight, but it seems like the only option.

Anyway, I'll order this and update the thread if there are issues.

Best,

Tim

 

[Igor]

Mouser: haven't passed one-by-one, but looks allrighty. The ferrite beads are bigger than I used, but will fit.
More inductance won't be worse here.

I'm wondering if cut dip-16 sockets will work for the 2181s since the spacing is pretty tight, but it seems like the only option.

This is exactly what I did too.

BTW. Helpful info from people who built MB500:

http://mnats.net/mixbuzz_500_build.html

http://www.groupdiy.com/index.php?topic=40493.0

 

[bkbirge]

Man, that's a great timesaver, thanks for sharing. Just finished my 51x rack and gearing up to start this project finally after having the PCB's for over a year.

Thanks Igor!

I scrolled through the whole thread again and didn't see an alternative BOM, but I looked through your suggestions and think I have everything covered.

https://www.mouser.com:443/ProjectManager/ProjectDetail.aspx?AccessID=d986302f5e

I'm wondering if cut dip-16 sockets will work for the 2181s since the spacing is pretty tight, but it seems like the only option.

Anyway, I'll order this and update the thread if there are issues.

Best,

Tim

 

[bkbirge]

Build in progress pic. Almost done, missing some parts from the BOM and some mismatches etc.

 

[bkbirge]

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?

 

[bkbirge]

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.