[BUILD] 1176 Rev A - Back to the beginning...

[Echo North]

Thanks. Here's where I'm at:

I built a signal tracer. I printed out the schems and have the exact signal path. with the power off, i traced the circuit. my problem is that the signal stops at the input transformer on BOTH of my units. (building a pair). i get a sort of loud hum with no signal from there on out.

i have quadruple or quintuple checked my wiring against the instructions. it all appears to be EXACTLY per the hairball site instructions. input xlr pin 1 is tied to chassis pin on xlr, ground continuity follows thru to the shielding on the cable between input tranny OUT and PCB IN.

here's the part that is stumping me: i unscrewed the input tranny from the chassis, and for one 5 minute stretch, the signal passed thru the input tranny. i traced it all the way thru the circuit to the output xlr, and it was all continuous. when i reassembled, it went back to no signal.

i can't tell, but it SEEMS as though there is maybe a short from ground to the signal outputs at the input tranny? since both units behave the exact same way, i have to assume there is some user error going on here. but for the life of me, i can't figure out what it could be.

with power not running to the unit, should i be able to trace signal past the input transformer? thanks for the help, really want to wrap this project up, it's kicking my ass!

How are you coming a long with your issue?

 

[hymentoptera]

Thanks. Here's where I'm at:

I built a signal tracer. I printed out the schems and have the exact signal path. with the power off, i traced the circuit. my problem is that the signal stops at the input transformer on BOTH of my units. (building a pair). i get a sort of loud hum with no signal from there on out.

...

here's the part that is stumping me: i unscrewed the input tranny from the chassis, and for one 5 minute stretch, the signal passed thru the input tranny. i traced it all the way thru the circuit to the output xlr, and it was all continuous. when i reassembled, it went back to no signal.

i can't tell, but it SEEMS as though there is maybe a short from ground to the signal outputs at the input tranny? since both units behave the exact same way, i have to assume there is some user error...

sounds like signal shorting to ground to me too. If you're still having problems can you post detailed pics of the soldering/wiring?

 

[dbonin]

Quick RATIO button test to make sure you are getting the right values from your ratios before you wire everything up.
ratio button resistence test
After placing resistors and soldering the radio buttons to the board, test the resistance between pads 6 and 4 while cycling through the four radio buttons
REV  A
ratio Ohms
20:1 47.2k
12:1 115.5k
8:1 171.4k
4:1 227.3k

http://youtu.be/YyR4vZIDNb8

 

[blackbird]

Hi everyone...

Im having an issue with my 2nd Blue stripe build.

The level going through the unit drops off a great deal.. I have to have output pot on full, and input pot pretty close to full to have the level stay the same when i put the Rev A in the chain...
Compression functions all seem to work, but calibrating it is impossible with insufficient level coming out of the unit..

The level drop seems to be related to the input, as pushing it up full lets me get to the threshold.

Anyone had this before? Got any clues?

Thanks!
Dave

 

[mikerl]

Hey all!

i have a 1176 Rev A that goes into Gain Reduction VERY early.. like 8-9 Oclock is where i have to leave it in order to get acceptable GR.  I also have to leave the output control very low to not clip my recorder (pro tools)

i have gathered that there is a way to adjust the internal threshold so that this thing goes into GR later, and i have more "sweep" out of the input pot, can anyone help with this?  i have searched around, and found a few bits of info, mostly mentioning that others have had similar issues, but i cant seem to find a solution... i am pretty green.. thanks in advance.

 

[hymentoptera]

Hi everyone...

Im having an issue with my 2nd Blue stripe build.

The level going through the unit drops off a great deal.. I have to have output pot on full, and input pot pretty close to full to have the level stay the same when i put the Rev A in the chain...
Compression functions all seem to work, but calibrating it is impossible with insufficient level coming out of the unit..

The level drop seems to be related to the input, as pushing it up full lets me get to the threshold.

Anyone had this before? Got any clues?

Thanks!
Dave

Recommend tracing input with a signal tracer or oscilloscope to find where the signal drops off at. Once you know what's happening, and where, we can start trouble shooting with you.

Off the top of my head I'm guessing the QBias adjustment has not been set up correctly and too much signal is dumping to ground at Q1. Perform step one of calibration if possible. If not, it's likely an issue with wiring, soldering, input transformer, or input attenuator.

 

[blackbird]

Hi everyone...

Im having an issue with my 2nd Blue stripe build.

The level going through the unit drops off a great deal.. I have to have output pot on full, and input pot pretty close to full to have the level stay the same when i put the Rev A in the chain...
Compression functions all seem to work, but calibrating it is impossible with insufficient level coming out of the unit..

The level drop seems to be related to the input, as pushing it up full lets me get to the threshold.

Anyone had this before? Got any clues?

Thanks!
Dave

Recommend tracing input with a signal tracer or oscilloscope to find where the signal drops off at. Once you know what's happening, and where, we can start trouble shooting with you.

Off the top of my head I'm guessing the QBias adjustment has not been set up correctly and too much signal is dumping to ground at Q1. Perform step one of calibration if possible. If not, it's likely an issue with wiring, soldering, input transformer, or input attenuator.

Thank you sir! Indeed the q bias seems to have been my problem here... My midway starting point must have been way off first go.. Before I began calibrating anything..

I adjusted the q bias while running audio through it before the actual calibration this time, and indeed now I have a better understanding of what the q bias actually is.. Hearing and seeing the level change and tone change whilst adjusting q bias was enlightening..

Thanks for ya help...!

Cheers
Dave

 

[hymentoptera]

Hey all!

i have a 1176 Rev A that goes into Gain Reduction VERY early.. like 8-9 Oclock is where i have to leave it in order to get acceptable GR.  I also have to leave the output control very low to not clip my recorder (pro tools)

i have gathered that there is a way to adjust the internal threshold so that this thing goes into GR later, and i have more "sweep" out of the input pot, can anyone help with this?  i have searched around, and found a few bits of info, mostly mentioning that others have had similar issues, but i cant seem to find a solution... i am pretty green.. thanks in advance.

Have you:
*Successfully performed first calibration step "Q bias adjustment"? DBonin video at youtube & mnats.net
*Checked voltages against  1176REVA_125_VOLTAGES.pdf? mnats.net

 

[Scheff]

Hello everybody!
Firstoff thanks to Mike and mnats for offering these awsome kits and to everyone contributing to this thread. It's a great ressource for someone who wants to get seriously into the DIY-thing like me.
I've built two Bluestripes and the build process was pretty smooth. I got a little release-pot issue which I think I'll be able to sort out by myself. If not I'll get back to it later...
Where I would need your help is an issue I don't have any explanation for. In two of the three studios I tested the comps in they sounded as great as you would expect. But in the third the output was really low and distorted and I couldn't get the output meter go beyond -20 or something. The GR meter seemed to behave normal. Since it was the last room I went to I suspected something was broken. But as soon as I got back to my own room everything was back to normal.
I read somewhere in this thread that you, Mike, said that these things are very sensitive to grounding issues. Could it be that the third room I went to hasn't proper grounding on their main line? All the other gear works fine though...
Since I'll be working in that room next week and would like to use my new tools for tracking it would be great if someone could help me track down that problem!
Thanks in advance! As stated earlier the help offered here is highly appreciated!
Cheers
Tobi

 

[hymentoptera]

Hello everybody!
Firstoff thanks to Mike and mnats for offering these awsome kits and to everyone contributing to this thread. It's a great ressource for someone who wants to get seriously into the DIY-thing like me.
I've built two Bluestripes and the build process was pretty smooth. I got a little release-pot issue which I think I'll be able to sort out by myself. If not I'll get back to it later...
Where I would need your help is an issue I don't have any explanation for. In two of the three studios I tested the comps in they sounded as great as you would expect. But in the third the output was really low and distorted and I couldn't get the output meter go beyond -20 or something. The GR meter seemed to behave normal. Since it was the last room I went to I suspected something was broken. But as soon as I got back to my own room everything was back to normal.
I read somewhere in this thread that you, Mike, said that these things are very sensitive to grounding issues. Could it be that the third room I went to hasn't proper grounding on their main line? All the other gear works fine though...
Since I'll be working in that room next week and would like to use my new tools for tracking it would be great if someone could help me track down that problem!
Thanks in advance! As stated earlier the help offered here is highly appreciated!
Cheers
Tobi

I want to suspect it's not the mains wiring in the 3rd studio, but instead whatever device you were going into next. Did you try multiple inputs for the 1176 output? Try going through other processors or channels that are known to work. Mixer channels, straight into the ADCs, etc.

To rule out mains, pick up one of those outlet testers link, they're like $5 and they show if an outlet is wired correctly depending on which of the 3 lights light up. Assume you're in the US.

 

[Scheff]

Thanks for the reply! I tried it in 3 different ways. Directly after the Mic-Pre and with two different ADC's (Apollo and Motu for the record) going stright into it. Unfortunately that room has no console to test it on an insert.
In the other rooms I tested it on inserts of consoles and directly patched into ADC's and everything was alright. 
I was also thinking about an impedance problem, but the effect was really extreme.
I'm in Germany, but will try to get one of those outlet testers.

 

[hymentoptera]

Thanks for the reply! I tried it in 3 different ways. Directly after the Mic-Pre and with two different ADC's (Apollo and Motu for the record) going stright into it. Unfortunately that room has no console to test it on an insert.
In the other rooms I tested it on inserts of consoles and directly patched into ADC's and everything was alright. 
I was also thinking about an impedance problem, but the effect was really extreme.
I'm in Germany, but will try to get one of those outlet testers.

Right. And with the tons of gain available I wouldn't think it was a balanced/unbalanced issue, as the console's inserts are likely unbalanced, but that should only constitute 6 decibels of difference anyways.

Have you had a chance to go back and try again at the third studio? Maybe bring some of your own cables, mic pre, etc?

 

[Scheff]

Problem solved. Just tried it again as a starting point to fix the problem. Nothing changed but the problem was gone. I really don't get it. Broken cable or something is highly unlikely, since GR metering showed a normal behaviour when I first tried it but I couldn't get the output up to a normal level. Really weird, but hey: it works!
Thanks for your input hymentoptera!
Now back to the bench! Building the third one! I love these things!  ;D

 

[remsouille]

Hey there!

I just finished my second rev A, it worked first try... at least I thought! After 20 minutes of use today, it went apeshit, buzzing and  making funny bird noises  ;D.
I did some minimal troubleshooting this afternoon, and it seems to happen after the unit gets hot. I cut the power, let it cool down for some time and it went back to normal, except for something I failed to notice earlier: when I crank the output up about 80%, it makes a pop and the meter's needle gets stuck at the right.
When it went crazy, dialing the output pot would get you into gremlin territory, and the needle would pop right much much much earlier, about 20% of the output range. Dialing the other controls didn't make any difference, only the output. Moving my hand over and in the box would also make the hum go crazy.
I'll do some more advanced troubleshooting tomorrow, but until then, does anyone have an idea where I should look into?

Thanks guys!!

 

[mnats]

I cut the power, let it cool down for some time and it went back to normal, except for something I failed to notice earlier: when I crank the output up about 80%, it makes a pop and the meter's needle gets stuck at the right.
I'll do some more advanced troubleshooting tomorrow, but until then, does anyone have an idea where I should look into?

Absolutely. The first line of the first post of this thread and the page linked from it.

 

[remsouille]

I really do feel stupid, sorry for not checking the faq the first....
The problem came from the 0,15uf cap in the input stage. I used very large orange drop caps so a big part of the leads were exposed, which picked up interferences from the meter wires.
Solved, thank you and sorry!!

 

[hymentoptera]

I wonder why we don't use shielded wire (same as elsewhere in the input and output) from XLR out to V meter? Tie shield to pin 1 of XLR out. Can't hurt, right? Afterall, it IS technically the output leads...

 

[evilcat]

Hey all!

i have a 1176 Rev A that goes into Gain Reduction VERY early.. like 8-9 Oclock is where i have to leave it in order to get acceptable GR.  I also have to leave the output control very low to not clip my recorder (pro tools)

i have gathered that there is a way to adjust the internal threshold so that this thing goes into GR later, and i have more "sweep" out of the input pot, can anyone help with this?  i have searched around, and found a few bits of info, mostly mentioning that others have had similar issues, but i cant seem to find a solution... i am pretty green.. thanks in advance.

Hi Mike,
You have to put a resistor in serie at the input of the sidechain, it's the pad 22 if I remember correctly, on the main board. For the value you'll have to make some test to find the one you like. I think I had put something like 250k, it creats 6dB less compression on sources like vocals (the difference would be less on percussive instruments). On my builds I've put the resistor on a toggle switch to have the choice between the standard version ("cool") and the new one ("hot") : for achieving the same amount of GR you'll have to push the input harder and reducing the output. It make the sound more coloured and the compressor less noisy.
Good luck

ben

 

[wimmy7986]

Hey all!

I'm starting to troubleshoot one of my units that is not compressing.  I've built a signal tracer, and believe I have found a problem.  Am I supposed to be seeing signal on both leads coming out of the input transformer?  Or just one of the leads?  Thanks

 

[Scheff]

I finished building the third one last week. I again have a problem concerning the release pot, but just can't find the mistake.
With short release everything sounds ok, but as i lengthen the release time the amount of compression is reducing.
Calibration worked out fine. I checked attack-release-pot wiring and cap/resistor values several times. I also checked all voltages I could find in other troubleshootings in this thread. Evertything appears to be up to spec. Any hints where to continue trouble shooting? I could definetely need some advice!
Thanks!