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I already ran some drums thru it, doing an A/B test with a buddy who has the Glue plugin.  the results were identical according to him on his listening setup (waaaaaaaayyyyyyyy better than mine).  We tested a bunch of different settings too.  it all sounded amazing.    Just need to learn what all the controls do now...  ::) ::)
 
mulletchuck said:
I already ran some drums thru it, doing an A/B test with a buddy who has the Glue plugin.  the results were identical according to him on his listening setup (waaaaaaaayyyyyyyy better than mine).  We tested a bunch of different settings too.  it all sounded amazing.    Just need to learn what all the controls do now...  ::) ::)

Have you done any of the calibration or just the pre trimming of the trimpots?
 
just pretrimmed it.  Since Ruckus hasn't posted the calibration info yet past the pretrimming, and it has been requested a couple times, i'm guessing he's still assembling the correct info for calibration.  It is thanksgiving weekend, after all.  He did say that if you don't clip that 4th leg on the VCAs that the unit will explode like the drummers in the Spinal Tap movies. 

Suffice it to say, the Pre-trimmed version with no calibration still sounds AWESOME!!
 
emrr said:
Since you mentioned it, wondering why the 4th leg has to be clipped.  I haven't studied the boards to see if there's a connection on that pin, only reason I can think it would need it.

Yes, my only goof in copper, Pin 4 on the board accidentally tied to ground.  Pretrimmed VCA's used in the sidechain, so Pin 4 should not be connected to anything.  If Pin 4 were to be connected to ground, would result in THD in excess of 1% in the sidechain.  Some would claim this doesn't matter, but I disagree.

Calibration will be up in couple hours.  I tried to hop on to write it up yesterday before thanksgiving dinner, but looked over at wife...and.... well you guys ever seen that scene in excorcist?  The one with the head spinning and pea soup?  Well it was kind of like that....only scarier......
 
Calibration, the quick quick quick version.  Assuming you've pretrimmed all of the pots as instructed, there will be little to do.  This was an exercise in gross overkill, and I'm actually removing half of the pots on my production version, majority are not needed.  Anyways:

Engage the "External In" Button.  This acts as a soft bypass, and makes compression impossible (unless of course you have something plugged into the TRS that's providing an external signal".  Put Blend knob full counterclockwise (Fully Dry).  Put threshold fully clockwise.  Set Gain to 0.  Set filters to "off".  Set attack to "30".  Set release to ".3"  Leave everything like this until instucted otherwise:

Now, feed the compressor a 1K signal at about +4dbu (probably somewhere around -15dbfs in your daw) and route it back into your daw.  Actual signal level isn't critical, just make sure it's somewhere around there.

Unity Gain (VR1L/R) - Toggle between bypass and comp in.  Adjust VR1L/R for unity gain (ie - same levels when the compressor is engaged as it is when it is in bypass)

DTrim & Magic - Now put the blend knob to fully clockwise (wet).  Look at the 1Khz signal coming back into your DAW with a frequency analyzer (I recommed blue cat's as it goes down to -120dbfs & it's free):

http://www.bluecataudio.com/Products/Product_FreqAnalyst/

You'll see the 2nd harmonic distortion node at 2Khz.  Adjust DTRIM (VR3L/R) for minimal distortion at 2Khz.  (While you're here, this would be a good time to hit the grind button so you can see/hear it working, just don't forget to turn it off before continuing with the calibration)

Now you need to crank the gain on the compressor to max (+18db).  So turn down the input signal going to the compressor a little so you don't clip your A/D when you do this.  I usually turn it down so my DAW meters read -22dbfs or so.  So anyways, crank the gain to max, adjust magic pots (VR2L/R) so there is minimal peak at 2K (you'll probably need to turn it counterclockwise quite a bit).  Repeat these 2 steps (DTRIM and MAGIC) until distortion won't go any lower.

Meter - With "external in" still engaged, look at the signal level coming back into your DAW and take not of it.  Now disengage "external in", and turn the thrshold knob until your level is 8db lower than the level I just said to take note of.  Adjust meter pot (VR201) until the analog meter says 8db.

Gain Knob - VR203(+Gain) & VR204(-Gain) allow to trim the gain knob to for accurate gain levels.  In other words, they will allow you to make sure when gain is at max (+18db), that you get exactly 18db of gain, and when gain is at minimal (-6db), that you get exactly 6db of attenuation.  Tread carefully here, as one will affect the other, and turning either of these pots will move your 0db point, so it is recommended that neither of these pots be turned more than a couple rotations. 

Export a 1Khz test tone and make sure that the level is low enough (usually -22dbfs or so here) that it will not clip your A/D coming back in when you crank the gain to max 18db.  Make sure blend is in wet position, engage "external in" button so compression isn't possible.

VR203 (+Gain) - The amount of gain at max should already be pretty accurate (typically 17.7db - 18.3db), so there will be very little adjustment to do on this one.  With the compressor hard bypassed, look at the level coming back into your DAW.  Now engage the compressor and crank the gain to max.  Adjust VR203 so that there is exactly 18db of gain.

VR204 (-Gain) - The "what" here is up to you, but I will tell you the "how".  Because of variance of linearity of the pot, tolerance of the pot (this is why I said to use the one closest to 10K here) as well as numerous other factors, if you trim VR204 so that you have exactly 6db of attenuation with gain full counterclockwise, then when you put the knob to "0" on the silkscreen, you will likely not have exactly 0db of gain.  For this reason I will usually put the gain knob at "0" on the silkscreen, and adjust VR204 so that I have exactly 0db (unity gain) when toggling the compressor in & out of hard bypass.  This however means that when you put the knob fully counterclockwise, it will likely read anywhere between 5-6db of attenuation, not exactly -6db.  It's a compromise here, but I would much rather have "0" be "0", and any gain above "0" to be accurate (for makeup purposes), then have exactly 6db of attenuation when knob is at "-6" on the silkscreen.

That's it for calibration.  Assuming you have pretrimmed VR4L/R & VR203 then there are no adjustments to be made for the sidechain or ratios.  Ratio's should be accurate worst case within 0.3 : 1 tolerance, (example 4:1 may be anywhere form 3.7:1 to 4.3:1).  This is normal.  There are too many outside variables here for all of them to ever be exact, and any attempt to adjust one will affect the other.
 
ruckus328 said:
emrr said:
Since you mentioned it, wondering why the 4th leg has to be clipped.  I haven't studied the boards to see if there's a connection on that pin, only reason I can think it would need it.

Yes, my only goof in copper, Pin 4 on the board accidentally tied to ground.  Pretrimmed VCA's used in the sidechain, so Pin 4 should not be connected to anything.  If Pin 4 were to be connected to ground, would result in THD in excess of 1% in the sidechain.  Some would claim this doesn't matter, but I disagree.

Calibration will be up in couple hours.  I tried to hop on to write it up yesterday before thanksgiving dinner, but looked over at wife...and.... well you guys ever seen that scene in excorcist?  The one with the head spinning and pea soup?  Well it was kind of like that....only scarier......

I know that look. It's the same look my wife has been giving me while work on this through Thanksgiving. Take your time...please don't take my eagerness as being pushy. You know how when you get a new toy you just want to play? :)

Edit: I'm a fool. I sold my interface a few months ago with the intention of replacing it, but never got around to it. Just an unbalanced Behringer  USB interface. DAMN! I need to swing by the studio and hopefully there is something there I can bring home.
 
Great, so I'm the first to have a problem :( when I power up my bottom board my power supply drops down to +/-4V, Do I have a short somewhere or is this a symptom of me using a 15V 100mA power supply? does it need more amperage?
 
benlindell said:
Great, so I'm the first to have a problem :( when I power up my bottom board my power supply drops down to +/-4V,

You can't power up a single board, the two boards are intertwined into one complete system, one won't work without the other.

benlindell said:
does it need more amperage?

Yes, 15V/100mA is not a sufficient supply and way below 500/51X spec, which is 133mA per channel (266mA for 2 channels).  Unit draws 180mA idle, 230mA if driving a 600R load, your supply will only provide half of what is needed.

benlindell said:
Do I have a short somewhere.

It's possible.  Check every IC is oriented correctly and then check again.  Ensure TL074's are not in backlwards ("U" indent on the IC body represents Pin 1 side). 10R resistors at very bottom right hand side of each board (4 on one board, 2 on the other) act as fuses on the +/-15V & +/-12V rails, verify they are not toast.  Check for bad/missed solder joints.  Fix power supply issues and then try to bring it up.
 
I feel like such a n00b, I had one TL074 backwards AND the 2180C :( now the power isn't getting pulled down so I gotta assemble it and try again with a bigger power supply.
 
TL074 might be shot.  2180C almost guaranteed is shot, they don't like being installed backwards.

Better double check your diodes and caps why'll you're at it.
 
Seems like they're all good, got everything back together and it seems to be working fine. Just calibrated it and it's working great!

Would you mind discussing the Grind circuit a bit, I have pretty good ears and I hear just the slightest difference between in and out, is it adding a touch of 2nd harmonic?

I'm excited to start working with this bad boy it's probably going to be sitting on my drum stem for a while, I still love my stereo pico compressor on the mixbus for the time being. only downside is that I now need to buy another lunchbox cause I have too many modules ;)
 
Ok, finished calibrating this guy tonight.    My gain knob gives me close to a range of 26db instead of 24db (-6 to +18 ).    It's a shame you can't get these as kits anymore.  I know a few guys who are very upset they couldn't pick up a kit for this module!!

 
Mine is up and running, what a sweet project!!!

I got it all calibrated, and it's VERY close to what was specified in the calibration notes. Ran a mix through it and it sounds good, I can tell it's going to be fun mixing through it!
I have a couple questions, and a problem:

#1- When you say "minimal peak" at 2k while calibrating the dtrim and magic, does that mean "NO" peak, or how low? I've only managed to get it below 90dB. If it's just secondary harmonics, I don't mind that so much, but if it's some kind of electrical problem, I'm not sure how to get it any lower, I've tweaked and tweaked those pots to the point of diminishing return.

#2- My Meter is not working at all. the LEDs light up, but I have turned the MET pot every way from Sunday A LOT, and the needle never budges. Is there any way to meter it or directly apply some voltage to see if the meter itself is just hosed?? (I'm also sending an email about this, Mike)

#3- Is there any way to turn the LED brightness DOWN? It's really cool, just a little bright and too distracting for my studio, compared to everything else in my rack. I assume this is just a matter of the correct value resistor? If I want it about 1/2-3/4 of the brightness it is now, what value would I start with, and where would be the best place to install it??

Thanks, and thank you for this project, it was a very fun and painless build!!

Eric
 
johnnyscotch said:
#2- My Meter is not working at all. the LEDs light up, but I have turned the MET pot every way from Sunday A LOT, and the needle never budges. Is there any way to meter it or directly apply some voltage to see if the meter itself is just hosed?? (I'm also sending an email about this, Mike)
Do you have it wired backwards? This meter has + and - terminals, and the silkscreen on the PCB has a tiny + to denote how to hook it up.
 
johnnyscotch said:
#1- When you say "minimal peak" at 2k while calibrating the dtrim and magic, does that mean "NO" peak, or how low? I've only managed to get it below 90dB. If it's just secondary harmonics, I don't mind that so much, but if it's some kind of electrical problem, I'm not sure how to get it any lower, I've tweaked and tweaked those pots to the point of diminishing return.
With external In engaged (control port held at ground) and mix at fully Dry harmonic node at 2K should drop off the charts when calibrated correctly.  You'll have to turn the magic pot counterclockwise (possibly all the way or close to it).  When external in is not engaged and mix at wet yes of course some hamonic distortion is to be expected, 90-100db sounds right.

johnnyscotch said:
#2- My Meter is not working at all. the LEDs light up, but I have turned the MET pot every way from Sunday A LOT, and the needle never budges. Is there any way to meter it or directly apply some voltage to see if the meter itself is just hosed?? (I'm also sending an email about this, Mike)
Check flyback diodes (two 1n4148's directly below the meter connector) are oriented correctly.  When you turn the unit on/off (with bypass button pressed in), do you see the needle move a tiny bit?  If so, issue is probably not the meter.  To be certain whether it is or isn't though put some voltage across the meter with a resistor in series to limit the current.  It's a 1mA at full throw, so halfway point (about 500uA) will be what you want to size the resistor to, just simple ohms law with whatever supply you're using to power the meter.  So for a 16V supply you'd have 16V / 0.0005A = 32K.

johnnyscotch said:
#3- Is there any way to turn the LED brightness DOWN? It's really cool, just a little bright and too distracting for my studio, compared to everything else in my rack. I assume this is just a matter of the correct value resistor? If I want it about 1/2-3/4 of the brightness it is now, what value would I start with, and where would be the best place to install it??

Yes, this is the 1K5 1W (R159) that has been frequently discussed.  This sets the current limit to the LED's.  So double its value will half the current and (more or less) half its brightness.
 

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