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

[Echo North]

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

Just one.  The one side is grounded at the sec side of the input.

 

[Echo North]

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!

If you apply a constant signal and adjust the release how much does the GR change in dB?

 

[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

Just one.  The one side is grounded at the sec side of the input.

Thanks so much! That's going to save me a lot of time.
One more question... Does ANY audio pass through the gain reduction section?  I'm not seeing any audio with the signal tracer.

 

[blackbird]

Hi Guys!..

Just after a bit of help...

Got a Hairball/Mnats Rev A build done..
All works, sounds great, Although after its been on a couple of hours, the sound thins out and gets weird.. To fix it, i turn the unit off then on again, and all is well..

Because the thinning is a gradual thing, i dont trust the unit ATM. If it was either thin or ok, it wouldnt be so bad, as u just turn off then on again when it goes bad..

Any ideas?
Thanks!
Dave

 

[Countrymetalguy]

So Ive built 2 of the REV D 1176 Hairball kits and just ordered a Blue Strip Rev A. After reading though, Is it safe to say the REV A wires up the same as a REV D? I know the PCBs are different , but other than that, the unit looks like all the controls and the trannys wire the same. Is this correct? or are there specifics to the Rev A that I need to be aware of? Thanks!

 

[Echo North]

So Ive built 2 of the REV D 1176 Hairball kits and just ordered a Blue Strip Rev A. After reading though, Is it safe to say the REV A wires up the same as a REV D? I know the PCBs are different , but other than that, the unit looks like all the controls and the trannys wire the same. Is this correct? or are there specifics to the Rev A that I need to be aware of? Thanks!

Same.

Attack cap/r are a different value.  Null adjust calibration a little different.  Will be covered in a Rev A specific guide that will be done soon.

 

[Countrymetalguy]

Cool! I'm looking forward to getting my rev A kit. Looking forward to the Rev A guide... And thanks for the smoking cyber Monday deal on those kits! I see you sold though em all. hairball stuff rocks..

 

[la2a4life]

Hey everyone, I've built my rev A power supply and I'm finding the readings a little low.

I'm at 29.3v at the 1.1k leg and -9.68v at CR6.
The in leg of VR1 is 40.5v and the out is at 29.3v.

I'm using a Sperry DM-6400 I bought at home depot to test so I'm wondering if its the dm.

Just wanted people opinions on whether this is a safe range to continue or if I should change out the voltage regulator to see if a different one will bump me up to +30v.

I double checked all my resistors and they're in the proper ranges, diodes and caps are all facing the right way.
I'm also getting around 30.5v at both ac inputs instead of the noted 25v. I also measured and my input power at L is at 122 AC.

This might be a dumb question but most of the threads I've found have had peoples readings be way to high instead of slightly low. If nothing else maybe this will help others in the future as well.

Thanks in advance!

 

[mnats]

Hey everyone, I've built my rev A power supply and I'm finding the readings a little low.

I'm at 29.3v at the 1.1k leg and -9.68v at CR6.
The in leg of VR1 is 40.5v and the out is at 29.3v.

Have you looked at the measured voltages from the FAQ linked from the first post?

 

[la2a4life]

Yeah, I checked all the build docs (hairball and mnats) and even went hunting on the forums before deciding to post here. Thanks

 

[Echo North]

I think a +/- 5% is acceptable.

 

[la2a4life]

Thanks!

 

[Spencerleehorton]

Hi Guys,

Im getting a boost in volume and more hum and hiss when i switch in slam mode, is this normal?

regards

Spence.

 

[blackbird]

Hi guys..

Just bumping my question with hope.

Cheers!
Dave

Hi Guys!..

Just after a bit of help...

Got a Hairball/Mnats Rev A build done..
All works, sounds great, Although after its been on a couple of hours, the sound thins out and gets weird.. To fix it, i turn the unit off then on again, and all is well..

Because the thinning is a gradual thing, i dont trust the unit ATM. If it was either thin or ok, it wouldnt be so bad, as u just turn off then on again when it goes bad..

Any ideas?
Thanks!
Dave

 

[Echo North]

That's wacky.

I'd start by checking the MNATs schematic w/ voltages when you turn the item on.

http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

Check yours against the voltages in red.

Then when she "thins" re-check the voltages for changes.  Let's start there.

Mike

 

[blackbird]

Hi mate..

Wacky indeed!

Ill do that asap.
Will report back

Thanks!
Dave

That's wacky.

I'd start by checking the MNATs schematic w/ voltages when you turn the item on.

http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

Check yours against the voltages in red.

Then when she "thins" re-check the voltages for changes.  Let's start there.

Mike

 

[Spadehead]

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

Have you got any pics of how ydid this? I am having similar issues with my RevA and 2 Rev D units where the input seems too high so I always need the I/o pots at or around 9am....

 

[Mr.Franky]

Hey everyone,

So I just finished building a rev. A kit. I had already built a rev. D kit once without any issues. With this one I do have an issue tough.
So I started calibrating the new rev A kit. Measured 0.775VAC at the input XLR. Then I moved on to the output XLR, setting the compressor to the settings as shown in the assembly guide;

Input = “24″ mid rotation
Output = “24″ mid rotation
Attack = full CCW (switched to off position)
Release = full CW
Compression ratio = 20:1
Meter mode = “GR”
Q-bias adjustment = full CCW
Shorting pin in “normal position”  connecting the two pins closest to Q13

But no matter what I do, I can't seem to get any volts going between the output XLR pin 2 & 3. So I went back and visually checked the entire kit on bad wiring, solder joints, making sure everything is connected correctly and I can't seem to find anything wrong in there. I also practically checked every resistor before soldering them into place. Caps all seem to be in the correct polarity as well. Couldn't guess what's wrong here. I find it very weird I'm getting no AC signal at all between pin 2 & 3 of the output XLR..

Any ideas?


Anyway, happy new year all!
Cheers!

 

[Echo North]

Hey everyone,

So I just finished building a rev. A kit. I had already built a rev. D kit once without any issues. With this one I do have an issue tough.
So I started calibrating the new rev A kit. Measured 0.775VAC at the input XLR. Then I moved on to the output XLR, setting the compressor to the settings as shown in the assembly guide;

Input = “24″ mid rotation
Output = “24″ mid rotation
Attack = full CCW (switched to off position)
Release = full CW
Compression ratio = 20:1
Meter mode = “GR”
Q-bias adjustment = full CCW
Shorting pin in “normal position”  connecting the two pins closest to Q13

But no matter what I do, I can't seem to get any volts going between the output XLR pin 2 & 3. So I went back and visually checked the entire kit on bad wiring, solder joints, making sure everything is connected correctly and I can't seem to find anything wrong in there. I also practically checked every resistor before soldering them into place. Caps all seem to be in the correct polarity as well. Couldn't guess what's wrong here. I find it very weird I'm getting no AC signal at all between pin 2 & 3 of the output XLR..

Any ideas?


Anyway, happy new year all!
Cheers!

You need to trace the signal to see where is stops.

Feed a 1K 0dB signal into the input.  Set your controls mid way, no GR, and test the signal referenced to ground at the XLR pin 2, + in t-pad, +out tpad, + either side of the input transformer, + at PCB input, - side of C7, and positive of out XLR.

Don't worry too much about the AC value they'll go down then back up.  Just look for the point where you get no reading (less than say 0.050 VAC).

Mike

 

[Echo North]

You need to trace the signal to see where is stops.

Feed a 1K 0dB signal into the input.  Set your controls mid way, no GR, and test the signal referenced to ground at the XLR pin 2, + in t-pad, +out tpad, + either side of the input transformer, + at PCB input, - side of C7, and positive of out XLR.

Don't worry too much about the AC value they'll go down then back up.  Just look for the point where you get no reading (less than say 0.050 VAC).

Mike

Hey,

The signal seems to stop at the output of the input transformer. It is installed correctly though. How could this be broken?



Regards,

Damaged winding if anything.  Check it at the output side + pin to confirm it's not a lifted trace.  Check the DC R  (ohms) between the + and - out put pin.