MixBuzz500 build/support tHread

[zayance]

Everything working good and sounding great, My bad eyes couldn't even see the the power cord i made for powering up the Time constant board was not good! :-[ :-[ : :
Its R40 that had burned, nothing to do with the rest everything was fine, thanks to your 10R resistors acting as fuses, and i had some minor contact in one of the ribbon cables...

I really need to go see the doc for visual check....

 

[dandeurloo]

Ok, I'm really close to powering this up!  Just a few small questions. I think I'm gonna try the 2181C mis adjusted for harmonics. Any tips on how far to mis adjust?

Also, C1. I read it can be lowered to 22pf. Any reason to want to lower it?  I have a few 330PG3 (33pf) silver mica's laying around I was hoping I could use those there. Any reason I can't use those?

 

[dbeeson]

Well, looks like I have a little problem.  The unit powers up fine but I only get one channel working.  I've checked over both cards and they are identical, I couldn't find any solder bridges.  I switched the ctl and SC cables around to make sure it wasn't a cable issue.  When I run audio through the non-working channel there's no sound at all, but the vu meter is working, the needle is jumping with the transients.  I'm wondering if there's a concentrated area (s) I should be looking at to solve this.  I'm assuming that the VCA is working if the VU is showing compression.  Any help would be greatly appreciated. 

 

[Igor]

Thanx! Will be happy when it works and makes a records!

A little correction, IC11 can have small dc offset (in case of tl074 for xample), so than please calibrate
with op-amp Not sure there will be difference more than 1-2 mv...anyway, let's be at safe side

Any reason not to use these epco caps in the sidechain?

No reason

Sidechain caps: just use regular poly'...nothing freaky, they don't affect the sound quality.
Of course, ceramic no good here, but poly, or film, 50-63V, enough....

Thanks, I can't believe how much cheaper those caps are then the other brands.    

Also, while at it is an AD713 a good chip for IC3 or no reason to use anything special here?

How are these sounding?  I can't wait to try it on some drums and subgroups.  

AD713 not "sounding" here. They are in sidechain. AD713 is fast, perfect dc-vise opamp.
To make very precision tracking, best imho. But hey, I used them by reason I bought
some hundreds for few bucks at surplus. Sidechain quad opamps; use LF347, enough!

Some confusion when installing the VCA boards and looking at Igor's prototype:
http://www.groupdiy.com/index.php?topic=39459.msg487509#msg487509
just to make shure expencive VCA's are not blown away.
In the new kits/PCB's the VCA boards should not be mounted up side down like in Igor's picture but they should be mounted like in my picture, correct?
At least that is what I measure

For THAT2181's, "1" is printed at pcb silkscreen.
You correct.
VCA "replacement" board can fit only one way.

Everything working good and sounding great, My bad eyes couldn't even see the the power cord i made for powering up the Time constant board was not good! Embarrassed Embarrassed Roll Eyes Roll Eyes
Its R40 that had burned, nothing to do with the rest everything was fine, thanks to your 10R resistors acting as fuses, and i had some minor contact in one of the ribbon cables...

Tony, happy about healthy baby, wish to make many platina's and good sound!!!!!

Ok, I'm really close to powering this up!  Just a few small questions. I think I'm gonna try the 2181C mis adjusted for harmonics. Any tips on how far to mis adjust?

Also, C1. I read it can be lowered to 22pf. Any reason to want to lower it?  I have a few 330PG3 (33pf) silver mica's laying around I was hoping I could use those there. Any reason I can't use those?

33pf is fine. Lowering...maybe, possible to hear the effect on ultraclean ribbon-twitter monitors...what VCA's do you use?

Harmonics. First, adjust for 0V DC. With op-amp in socket (it matters).
Than, listen after ratios check, when adjusted.
Than, use good soundcard and kinda RMAA. Or: one turn of 24-turn pot will do the job.
Listen again after mis-trimming. Up to your taste, more compression "dirt"
but more "size" cab be better or worse
In general, I prefer analyzer for distortion calibration.
Difference between 0.02% and 0.07%THD calibrated at 0dbV, unity gain,
can be heard with Adam S3a, Lynx2, my CRM as level control setup.
(mind, I don't have acoustic treatment at workshop

Well, looks like I have a little problem.  The unit powers up fine but I only get one channel working.  I've checked over both cards and they are identical, I couldn't find any solder bridges.  I switched the ctl and SC cables around to make sure it wasn't a cable issue.  When I run audio through the non-working channel there's no sound at all, but the vu meter is working, the needle is jumping with the transients.  I'm wondering if there's a concentrated area (s) I should be looking at to solve this.  I'm assuming that the VCA is working if the VU is showing compression.  Any help would be greatly appreciated.  

That's strange. Does unit passing audio in bypass? I.e. when only audio pcb is inside the slot,
it should pass audio because bypas relays connecting in and out.
If bypass is OK, switch comp IN by connecting the ribbons, front panel pcb,
its power supply and control pcb; it can be good idea to trace the signal with scope....
For now, please let know about bypass. Visual check can help as well.

 

[dbeeson]

Thanks for the quick reply Igor.  The audio pcb is passing audio in bypass but not when the compressor is engaged.  But the meter does show compression.  I'm only running audio through one side at a time.  When the compressor is engaged, there is no hiss or a sound of any kind.  The signal is not getting to the output.  I've been meaning to take some pictures but my camera is having issues. All ribbons are where they should be.  Thanks again for the help. 

For the IC11 calibrating trick, I do leave IC11 in place, I just stick a small lead in the hole of pin 7 before I replace the IC. The IC wedges the lead in the socket nice and tight. 

 

[dandeurloo]

AD713 not "sounding" here. They are in sidechain. AD713 is fast, perfect dc-vise opamp.
To make very precision tracking, best imho. But hey, I used them by reason I bought
some hundreds for few bucks at surplus. Sidechain quad opamps; use LF347, enough!


33pf is fine. Lowering...maybe, possible to hear the effect on ultraclean ribbon-twitter monitors...what VCA's do you use?

Harmonics. First, adjust for 0V DC. With op-amp in socket (it matters).
Than, listen after ratios check, when adjusted.
Than, use good soundcard and kinda RMAA. Or: one turn of 24-turn pot will do the job.
Listen again after mis-trimming. Up to your taste, more compression "dirt"
but more "size" cab be better or worse
In general, I prefer analyzer for distortion calibration.
Difference between 0.02% and 0.07%THD calibrated at 0dbV, unity gain,
can be heard with Adam S3a, Lynx2, my CRM as level control setup.
(mind, I don't have acoustic treatment at workshop

Igor Thanks

So C1 probably effects the highend clarity a little.  If I am right the lower the cap value the more the high end may roll of a little?

Thanks for tips on mis adjusting for Harmonics!

 

[dbeeson]

I used the old patch cord (w/ .1uf on the tip) into an amp to probe the audio path and it seems that the dbx 202xt is faulty  :-[  I get a signal at I_in but nothing at I_out.  I measured +17.3 at +E and -17.3 at -E with the meter.  Could there be anything else to check?  If I desolder and remove the vca from the circuit and install the 1k25 resistor between I_in and I_out, should there be signal at the output if I switch in the circuit?  So close...

 

[reanimatorstudio]

Could there be anything else to check?  If I desolder and remove the vca from the circuit and install the 1k25 resistor between I_in and I_out, should there be signal at the output if I switch in the circuit?  So close...

What do you measure on the vca control port? Does it change if you change the make-up gain pot?
Did you put a drop of solder on SJ1?

 

[oceres]

first I've to say this project has been pure joy to assemble! two thumbs up

so the thing is I have all of the pcb's stuffed and ready to go but found out that I was missing TL072 (IC10)

Can it be replaced with something else without any mods atleast until I get some TL072's? I have OPA2604 and NE5532

...It's almost finished and I'm anxious to fire it up  ;D

 

[Igor]

So C1 probably effects the highend clarity a little.  
If I am right the lower the cap value the more the high end may roll of a little?

Don't think the audio effect will be hearable...anyway.

I used the old patch cord (w/ .1uf on the tip) into an amp
to probe the audio path and it seems that the dbx 202xt is faulty  
Embarrassed  I get a signal at I_in but nothing at I_out.  

Inverting input of opamp in inverting connection is virtually 0 ohm to ground, nothing supposed to
be here till it starts to clip (this is the trick of op-amp, nothing at inverting input but yes,
there's an output
In other words, opamp tries to maintain same signal at - input as it see at + input. + input is grounded.
Try at op-amp's out, IC11B, pin7. Another opt: like Reanimator wrote, check what happens at control port-
maybe somehow VCA cuts the signal.

I measured +17.3 at +E and -17.3 at -E with the meter.  
Could there be anything else to check?  
If I desolder and remove the vca from the circuit and install the
1k25 resistor between I_in and I_out,
should there be signal at the output if I switch in the circuit?

If 1k25 installedbetween I_in and I_out, yes, signal supposed to be at the OP-AMP OUTPUT,
but don't de-solder VCA yet....
Seems, solder jumper is not installled or something simple.

Can it be replaced with something else without any mods atleast until I get some TL072's?
I have OPA2604 and NE5532

5532 not very precision dc-vise, and not like high impedances; ratios can be slightly fubarooed; try opa2604, it is jfet opamp; than replace it with tl072 or another jfet opamp,
dc precision and speed (at least 10v/usec) this is what means here.

 

[dandeurloo]

Hey guys,  these are my relays.

http://www.citrelay.com/Relay%20Products.htm

I can't figure out what resistance they are because I don't know what watts it will be running at?  Seems to me running at 12vdc and .15w they have a coil resistance of 960r.  But I'm not sure if .15w is the correct value? 

If so then 960 divide by 6 = 160r.  So both R98 and R87 should be 160r .5w resistors. 

Thanks for any help clarifying in advance.

 

[Igor]

Hey guys,  these are my relays.

http://www.citrelay.com/Relay%20Products.htm

I can't figure out what resistance they are because I don't know what watts it will be running at?  Seems to me running at 12vdc and .15w they have a coil resistance of 960r.  But I'm not sure if .15w is the correct value? 

If so then 960 divide by 6 = 160r.  So both R98 and R87 should be 160r .5w resistors. 

Thanks for any help clarifying in advance.

Dan, easy way: just measure the coil resistance with multimeter. 160r can be 150r, carbon cracked, 1/2w, 20%.

 

[dandeurloo]

Got it!

One more question then I am ready to test I think. 

Quote
and don't forget to link the 3 point on the side of switch on off on if not the relay could not work and the unit stay in bypass
That's right Smiley
This jumper is for people who will use the unit in GSSL or Gyraf mode only,
but... just put a solder joint here to have both options.


Do I just need to do a solder bridge over all these points as well?  Like SJ1 and SJ2?

Thanks

 

[zayance]

Do I just need to do a solder bridge over all these points as well?  Like SJ1 and SJ2?

Yep

 

[oceres]

5532 not very precision dc-vise, and not like high impedances; ratios can be slightly fubarooed; try opa2604, it is jfet opamp; than replace it with tl072 or another jfet opamp,
dc precision and speed (at least 10v/usec) this is what means here.

thanks Igor! I tried it with opa2604 in IC10 and it worked yay! Calibration was a breeze and the unit sounds absolutely wonderful. It's my first buss compressor so I'm blown away how good it sounds. I have 4x that2181A with LME49710 and compression is so clean and smooth it's like hitting transients with white pillows... if that makes any sense ;D

ps. Do I need to re-calibrate SYM 50k if I swap out IC11 (ne5532) for opa2604 too?

 

[dbeeson]

Thanks for the help Igor.  I switched all dips on each board and found the faulty board to be working when I did so.  So I narrowed it down to the DRV134.  Just ordered a new one.  Thanks again.

 

[Igor]

thanks Igor! I tried it with opa2604 in IC10 and it worked yay!

HURRAY!!!!!!!!!!!!!!!!!!

Calibration was a breeze and the unit sounds absolutely wonderful. It's my first buss compressor so I'm blown away how good it sounds. I have 4x that2181A with LME49710 and compression is so clean and smooth it's like hitting transients with white pillows... if that makes any sense.

I feel happy Now, do a great track with MB500!!!

Yes, 2181A+LME49710 combo should work great.
My personal opinion, 2181A don't worth additiional $3 per VCA, soundwise.
Neither it is tooooo sterile, no, it still has some VCA sound if you listen it
in hi-res monitoring setup, and the diffrence between perfectly adjusted
for minimum distortion A or B grade is almost negligible.
For me, quartet of 2181B after trimming sounds more "alive".
Anyway, it is just my opinion...
Paralleling VCA's does not lowers minimum possible distortion;
but, it increases the dynamic range, what is important IMHO.

Smooth transient response is matter of timing capacitor and PCB layout, as well.
I did not used tantalums here by this reason; one 0.47uf poly cap used for
all release settings except A, with a little rearranging the release switch if
you guys noticed. Time constants remains same, anyway.

ps. Do I need to re-calibrate SYM 50k if I swap out IC11 (ne5532) for opa2604 too?

Maybe. 5532 is not best dc precision opamp.

I switched all dips on each board and found the faulty board to be working when I did so.  So I narrowed it down to the DRV134.  Just ordered a new one.  Thanks again.

Yes, DRV134 is good chip.
In general, if we got to "balancers", line receivers/drivers, here is what I think.
Using even best opamps for "re' and 'balancing" the line not worth this
neither cost nor quality-wise.
It never will sound better or cleaner than TI or THAT chips, without
talking about harmonic content.
I avoided capacitors in soundpath at every possible places, to get
minimum unwanted sonic artefacts, thanx to these chips.
And, another thing. Try to feed 1khz 5V P-P squarewave into GSSL's output balancer,
sum the + and - output with pair of 2k resistors and 100R trimpot and adjust for less possible signal;
than, see on scope what you get here.
As well, GSSL output balancer does not likes when - is connected to ground.

These are the reasons why I used "balancing" chips.
INA137, DRV134, THAT1646, THAT1246, can be used in MixBuzz500.
Beware of SSM2142, it is not best line driver. However, SSM2143 can be used at the input.

 

[kibadachi]

Can someone who already built the mixbuzz500 recommend part numbers for

CAPACITOR-CERAMIC/NPO/COG 2.5MM PITCH  22P      and for

CAPACITOR-NPO/COG/SILVER MICA  33P      C2,5-3 
                                                56P      C5/2.5  C1

Preferable Mouser, or Farnell.
 
Thanks

 

[zayance]

Can someone who already built the mixbuzz500 recommend part numbers for

CAPACITOR-CERAMIC/NPO/COG 2.5MM PITCH  22P      and for

CAPACITOR-NPO/COG/SILVER MICA  33P      C2,5-3  
                                                56P      C5/2.5   C1

Preferable Mouser, or Farnell.
 
Thanks

22P
http://fr.mouser.com/Murata/Passive-Components/Capacitors/Ceramic-Capacitors/Multilayer-Ceramic-Capacitors-MLCC-Leaded/_/N-4gzxjZ1z0zlft?P=1z0x4jpZ1z0y7ye
33P
http://fr.mouser.com/Murata/Passive-Components/Capacitors/Ceramic-Capacitors/Multilayer-Ceramic-Capacitors-MLCC-Leaded/_/N-4gzxjZ1z0zlft?P=1z0x6f9Z1z0y7ye
56P
http://fr.mouser.com/Murata/Passive-Components/Capacitors/Ceramic-Capacitors/Multilayer-Ceramic-Capacitors-MLCC-Leaded/_/N-4gzxjZ1z0zlft?P=1z0x638Z1z0y7ye

Pick your choice 

 

[kibadachi]

Thanks.

You guys respond faster than i can ask ;D