Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1840 on: August 20, 2020, 12:39:31 AM »
JMan check your attack/release PCB super closely.  Make sure the values are good and everything is soldered well and the release legs are ok.

Make sure those 6.8 tantalums are in correctly.

Make sure all your wire headers are in correctly.

Make sure you release and output pots are not swapped.  Release is blue, output is grey.

Mike
Hairball Audio, LLC
DIY Parts and Kits
https://hairballaudio.com

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio


JMan

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1841 on: August 20, 2020, 02:29:16 AM »
Oh brother, I totally have the output and release pots swapped!

I’ll switch them tomorrow and try again.  Will report back!

JMan

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1842 on: August 21, 2020, 09:30:32 PM »
Okay, so I got the pots in the correct places.  I also found that R57 on the attack/release board was the wrong value by several orders of magnitude, so I put in the correct value.  I went through the entire circuit and triple checked my resistor color codes and other component values, and everything else checks out, including ratio and meter boards and now the attack/release board.

This mostly fixed the issue.  However...

In step 3 of calibration (where I was having trouble), turning on the attack pot does drop the voltage from 2.44v now that I've corrected those components, but not all the way back down to 0.775 -- only to 1.025.  If I adjust that down with the output control, then the "attack off" voltage drops accordingly.  In other words, I'm not getting the full 10dBu attenuation. 

Additionally, my voltages at TP22, Q7-10, and CR2 went further out of whack.  Most everything there shot high, particularly at the higher ratios (which it was already doing, but more so now -- for example, I've got 0.450v at Q7 as opposed to the expected 0.377v).  I've also still got a higher-than-expected voltage at Q5.

Having said all that, the unit does pass audio and compresses, and on a fun little test running bass guitar through it and then some drums, it sounds fabulous!  I'm just wondering what I'm still missing to get it all the way to where it's supposed to be.

Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1843 on: August 23, 2020, 11:46:59 AM »
Okay, so I got the pots in the correct places.  I also found that R57 on the attack/release board was the wrong value by several orders of magnitude, so I put in the correct value.  I went through the entire circuit and triple checked my resistor color codes and other component values, and everything else checks out, including ratio and meter boards and now the attack/release board.

This mostly fixed the issue.  However...

In step 3 of calibration (where I was having trouble), turning on the attack pot does drop the voltage from 2.44v now that I've corrected those components, but not all the way back down to 0.775 -- only to 1.025.  If I adjust that down with the output control, then the "attack off" voltage drops accordingly.  In other words, I'm not getting the full 10dBu attenuation. 

Additionally, my voltages at TP22, Q7-10, and CR2 went further out of whack.  Most everything there shot high, particularly at the higher ratios (which it was already doing, but more so now -- for example, I've got 0.450v at Q7 as opposed to the expected 0.377v).  I've also still got a higher-than-expected voltage at Q5.

Having said all that, the unit does pass audio and compresses, and on a fun little test running bass guitar through it and then some drums, it sounds fabulous!  I'm just wondering what I'm still missing to get it all the way to where it's supposed to be.

Those voltages are not crazy out.  They seem fine.

Not sure what's happening with your calibration step.  Have you looked at some of the calibration videos on you tube?  You might be doing it wrong?

Mike
Hairball Audio, LLC
DIY Parts and Kits
https://hairballaudio.com

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio

JMan

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1844 on: August 23, 2020, 09:05:23 PM »
Well, whatever I was doing wrong before, I got it right this time.  Unit is fully calibrated and racked up, and it looks and sounds fabulous!  Thanks Mike for such a fun build.  I look forward to doing a few more of these units in the near future.