MixBuzz1 Build/Support thread

[chefducuisine]

Excellent Work Bastrika !!!

Mine is finished, too and working fine. I added the analog meter and made a new LED Meter board containing all the rocker switches - really tight fit.
Currently I am working on the VU Meter illumination which is a bit tough to integrate in a Sifam PPM14... will post pictures of the unit when finished.

Can somebody please check if the 12V Regulator on the Power Supply board is running hot. Mine is getting hot after 5 min but still touchable. Perhaps because it has to burn >6 Volts...


Regards,


Chris

 

[tomcat]

Did it for a sifam ppm14. Its easy if you use rectangular leds with just 2mm thickness. 3mm is too much.

 

[Igor]

@jandoste: please check the wiring and components values.... If everything is OK, should work.
1m5 instead of 1m2... should work, I think.
BTW, are you checking the level with or without MIX?

 

[Igor]

@briomusic:

Still trying to get to the bottom of my metering problem
(meter only showing right hand signal on both bargraphs).
On the link from the meter driver to the led pcb there are two connections named LEDVU-7 and LEDVU-9.
Both of these have voltages that change according to the level of the input signal.
However, LEDVU-7 has a positive voltage and LEDVU-9 has a negative voltage. I guess they should both be positive?

(Just trying to isolate the problem to either the driver or led board...)

That's strange...Please check patiently the voltages at IC202C, IC203C, IC202B, IC203B.
Yes, the voltages should be positive, more signal more voltage.
In gain reduction, there should be positive voltage going down with more db gain reduction.


BTW, if both meters shows same, there can be a prob as well in LED meter board.
Check for oscillation at IC1 (4011), pins 10/11, etc. Check all IC's are in right way in their sockets etc.

@marcfrom:

I building two DBX202X REPLACEMENT BOARDS.

If i understand well for CBP20, CBP21, CBP22, CBP23 i can use any value between 47N and 220UF.

Someone can confirm and what the best value for this caps?

X7R, ceramic caps, 50V, pitch 2.5mm, 47....220 nF.


@bastrika:


WOA!!!!

Great build! Hehe, I can recognize Sontec at the pic, right?

DIY front panel, as well?

All thumbs up!!!!!

@chefducuisine:

Can somebody please check if the 12V Regulator on the Power Supply board is running hot.
Mine is getting hot after 5 min but still touchable. Perhaps because it has to burn >6 Volts...

Depending on relays resistance and LED's or incandescent lamps used.....
Mine running arround 40 degC, it is OK, when I have +23 at room, yes, the Israeli winter, haha!

 

[briomusic]

@briomusic:

That's strange...Please check patiently the voltages at IC202C, IC203C, IC202B, IC203B.
Yes, the voltages should be positive, more signal more voltage.
In gain reduction, there should be positive voltage going down with more db gain reduction.

Have just done this and ended up finding a reversed diode in the left side rectifier...  :-[
So now I have positive voltages proportional to input level on both channels

but.....

BTW, if both meters shows same, there can be a prob as well in LED meter board.
Check for oscillation at IC1 (4011), pins 10/11, etc. Check all IC's are in right way in their sockets etc.

yes it seems I get no multiplexing, just both (L+R) signals summed before they go into the LM3914s.
I will have another look at the LED_front_PCB, thanks.

 

[Igor]

I had a little mind this was F@@@ng diode!!! Hurray! Yes, just check if there's multiplexing, 4011 and 4016 are alive....
you should find it quickly.

 

[briomusic]

Hey Igor, I set the metering problem aside for the moment (it's not really mission-critical if the level meter is in stereo...) and tried to adjust the SYM trims for minimum distortion. The only analyzer I have available is a software based frequency analyzer. I think I could see the distortion, in bypass there was only one spike at 1khz, with some gain reduction applied there were additional spikes at other, higher frequencies (harmonics). I tried turning the little SYML/SYMR-trimpots, but the level of these harmonics didn't change at all, along the whole range of the pot. Am I doing something wrong? Do I need better measuring equipment? Cheers Briomusic

PS: this was the SYM trims on the audio section, not sidechain. I only have one VCA installed each channel.

 

[chefducuisine]

Guys,

as promised: Here are the pictures of my version.
I have added all options including the Att/Rel. Mod Igor suggested.
Because I like the look of the original there is also the Sifam Meter. To fit everything to the frontplate I had to make a new LED Meter PCB. All switches have been mounted to this new meter board, too.
Many thanks to Frank for the Frontplate and the assistance he gave me in the design phase as this was the first time I used FP Designer... result is pretty stunning.

Up until now I did not receive the soundpath upgrade - but had a few 2181 lying around and decided to buy the few missing bits to get this thingy running.
I still have to redo the meter calibration with more precision. At the moment it is only set up roughly.

Regards,

Chris

http://twin-x.com/groupdiy/albums/userpics/MixBuzz_Front.jpg

http://twin-x.com/groupdiy/albums/userpics/MixBuzz_innen.jpg

 

[zayance]

Very Nice  8), Cool idea for the LED Meter PCB....

 

[tomcat]

Beautifull!! Good that i didnt order my cases already

 

[Igor]

@chefducuisine:

Man!!!! I am jealous in a good sence!!!!!

This looks SOOO good, and the inside work is awesome!!!!

Regarding the soundpath upgrade, please mail, you had to receive it about a month and half ago with others.
BTW, where did you found these ALPS pots used on attack/release?

 

[Igor]

Hey Igor, I set the metering problem aside for the moment (it's not really mission-critical if the level meter is in stereo...) and tried to adjust the SYM trims for minimum distortion. The only analyzer I have available is a software based frequency analyzer. I think I could see the distortion, in bypass there was only one spike at 1khz, with some gain reduction applied there were additional spikes at other, higher frequencies (harmonics). I tried turning the little SYML/SYMR-trimpots, but the level of these harmonics didn't change at all, along the whole range of the pot. Am I doing something wrong? Do I need better measuring equipment? Cheers Briomusic

PS: this was the SYM trims on the audio section, not sidechain. I only have one VCA installed each channel.

Brio: don't measure the distortion with compression!
Compression IS kinda distortion

Adjust the soundpath distortion without compression first, than adjust the ratios etc,
just go with the test procedure. Let us know what was the prob with the meter, or give me more info to help fix it.

 

[briomusic]

Hi Igor, thanks so much for your help! I have a very busy session at the studio, so my thinking was "good sound now, good looks (metering) later"  
I will try again with the SYM adjustment today, as I would like to use the mixbuzz in the current session.
As for the metering, I have narrowed the problem down to the multiplexing, but might have to borrow a friends scope to investigate further. I haven't given up on it just delayed. I will get back to you about it!
Cheers, Briomusic

ETA: managed to do the THD calibration according to instructions, and indeed, an additional 2kHz spike (with a 1kHz test tone), appears and disappears when turning the SYML/R trims 

 

[chefducuisine]

Many thanks for the kind words!!!

Because of the high number of requests  :

- Supplier for the Sifiam Meter as well as the Sifam Knobs was RS-Online (Allied Electronics in the US)
- All Meter and Switch LEDs are of 1,8mm type from Farnell, but most suppliers carry them (see Farnell No 1142455 for reference)
- The Mini Rocker-Switches are from APEM. I had them on stock, but I think I ordered from RS-Online, too. However, there are a number of manufacturers for those type of switches (e.g. CK, Tyco, Omron, Knitter)
  For reference please see http://at.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0664200

@ zayance & tomcat: Drop me a line if you need the fpd file for the frontplate or the LED Meter PCB Layout.

@ Igor:
Many, many thanks for the kind words. No need to be jealous - at least you are the 'father' of this baby. ;D ;D ;D
Currently I am trying to calibrate both meters for GR. Can you please tell which trace to cut according your suggestion a few pages before?!

I've sent a mail as requested for the Soundpath upgrade.

The Alps RK Pots are from 'Reichelt' (unfortunately german / stereo versions only available):
- Attack - 100k log
  http://www.reichelt.de/6mm-Potis-stereo/RK27112-LOG100K/index.html?;ACTION=3;LA=2;ARTICLE=73835;GROUPID=3136;SID=31rTUtMqwQAR8AAGWhXk04cd640906b14695a377dc44213736265
- Release - 1 Meg lin
  http://www.reichelt.de/6mm-Potis-stereo/RK27112-LIN1M/index.html?;ACTION=3;LA=2;ARTICLE=73831;GROUPID=3136;SID=31rTUtMqwQAR8AAGWhXk04cd640906b14695a377dc44213736265
- Mix 10k log
  http://www.reichelt.de/6mm-Potis-stereo/RK27112-LIN10K/index.html?;ACTION=3;LA=2;ARTICLE=73827;GROUPID=3136;SID=31rTUtMqwQAR8AAGWhXk04cd640906b14695a377dc44213736265

Regards,


Chris

 

[Igor]

"good sound now, good looks (metering) later"

O! Dats cool))) Well, it SHOULD sound good!  ;D ;D ;D

and indeed, an additional 2kHz spike (with a 1kHz test tone), appears and disappears when turning the SYML/R trims

2nd harmonic, aye!!!!!

BTW. Who saw the "Six Shooter" movie?
I watched 10 times at least. "A great source of amusement!"  ;D ;D ;D ;D

Interestingly. I usually choose for MixBuzz as right amount 0.04-0.07% of second harmonic,
when adjusting while listening (Lynx2, Adam S3a, my passive CRM).
Source...Mixes before mastering in 24/96, and, as great test source,
I like Metheny/Jopek, Upoenie, song nr3 in album, or... Morph The Cat.

What will be the right amount for other people here?

No need to be jealous - at least you are the 'father' of this baby.

As true Addams, I have to say something, right?  
Of course, in good sense. It looks really gorgeous. Tell us about sound etc.
And thanx for links to components!

Here is the guide how-to run 2 meters, LED and analog together.

Check the picture. Cut the trace at top layer.
Solder one leg of 1K resistor to point A, second leg to wire, wire to point B.
(1K is anti-oscillating resistor which should be at opamp's out).

Connect your analog meter to 4-pin terminal, with 2k trimpot in series to meter's coil - for xample,
trimpot goes between pin4 and meter's coil +.
Done.
Now you have 2 separate trimpots to calibrate both LED and analog meter.

 

[piano]

HELP! Trim pots for meter. I have two

BOATER POTS that say 123T W503 on them; (in the picture it has a 134C W103 on it - can I use 123T W503?)

 

[mata_haze]

Hello Everybody,
my unit is nearly finished I only have one problem and I hope someone who has finished the unit could give me some read-out.
unit passes audio,makeup works but no compression.
I have checked the Threshold pot is wired properly (I get a swing of + and - 12V at the wiper) and the RAtio and attack-release pots are ok.

I have carried out the following measurements:
on IC3 on both PIN 8 and PIN 14 I have the following: (DC)

RATIO          Voltage Swing
1.5                                3 - 17 mV
2                               203 - 216 mV
4                           no swing 156 mV (fixed)
6                               361 - 362 mV              
8                               380 - 381 mV
10                             391 - 392 mV

on the same Chip (Ic3) I have a swing of 5 to 150 mV on PIN 1 and 7. (DC)

I am trying to figure out were my mistake lies I can see that the DC voltage runs all the way from the wiper of the threshold pot to PIN 1 and PIN 7 of IC3 and then it gets "messy" on PIN 8 and 14, also no DC after the diodes D6L and D6R.
also the makeup works fine so IC5B it's ok.
I am using IGOR's mod to implement a continuos pot for attack and release, so I am not using the stepped lorlin.

any help (and/or measurements from working units) will be VERY much appreciated!

Best,
Mattia.

 

[mata_haze]

Sfter further investigations I have found out that the sidechain signal stops before hitting the detector.
I can trace the a sinewave (1V RMS) up until the left side (looking at schematics) of R14L and R14R and then it disappears.

by checking TP1 and TP2 I found out there is no sinewave there either.
I am assuming the VCA works in a "current fashion" rather than voltage and then IC1A and IC5A then convert the current into voltage again hence the TP1 and TP2 afterwards.

can anyone comment on this?

I am not sure what the " - CONTROL " and " + CONTROL" means on pins 5 and 7 of the VCA, are they not just supply +-15 VDC? or should I expect some signal there too?

EDIT: I have +15 VDC on pin 7 and -15VDC on the 5k1 resistor attached to pin5. there is -2.85 Vcc on pin 5 of the VCA.

Best,
Mattia

 

[piano]

What is the silver strip use for and where in the kit?

Are the strip of pins for stacking the PCB on top of each other?

 

[zayance]

Left is the molex crimp connectors, picture is no good but looks like it, and yes right is for stacking the PCB's of the front panel i believe...