Hairball 1176 tpad and output pot problem

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darkus

Well-known member
Joined
Feb 16, 2014
Messages
108
Location
Vantaa, Finland
Hi, i just finished my second Rev D build. I was going to add stereo link boards to this and my excisting 1176 but i noticed the new units input and output are off.

Both units are calibrated on their own with the same signal to perfection. They measure the same but the controls are wayyy different.

This is the unit ive had a while
https://www.dropbox.com/s/b09s9ntwlzutpqo/Photo%2023.10.2014%2022.56.07.jpg?dl=0

And this is the new one
https://www.dropbox.com/s/9rll0tei2v5qj6e/Photo%2023.10.2014%2022.57.02.jpg?dl=0

I took these pics right after the 3rd calibration step.  I calibrated them at the same time and i did it few times as well to get it right and i couldnt believe how hard the 2nd unit was to set up.

I dont know where to look for with this issue. Help? :-[

EDIT: To me this doesnt seem the normal tolerance of Bourns T-pad or the ouput pot. Everyone says that for the 3rd calibration step you have to crank your input but on this second unit i had to set the controls to the opposite of what everyone says....i started the final calibration step by adjusting output xlr pins to read 0.775V with output pot, then flick the attack switch and set the output to read 2.44V with the input knob. I have checked my input wiring if im just unbalancing somewhere and my wiring is exactly like in the other unit that works.
 
i don't remember measuring the output for .775v.. I do remember measuring the input signal at the xlr to .775v.

Did you follow Mnats calibration from youtube? I wouldn't expect the knobs would be more than 20% off from one another.
 
I followed the hairball guide as with my first build.

Turns out i had Q5 backwards.....stupid me. This thread can be removed and ill go shoot myself meanwhile.

Unit works as meant now
 
Anyone have a hairball t-pad that chatters or crackles as you turn it? If so how did you shut them up? This noise makes it impossible to ride the fader on the fly. Should the 3 pins in the center be grounded?
 
Bobby Baird said:
Anyone have a hairball t-pad that chatters or crackles as you turn it? If so how did you shut them up? This noise makes it impossible to ride the fader on the fly. Should the 3 pins in the center be grounded?

I have a similar problem with both of my 1176 but its the output pot that is scratchy. I might try some CRC on them.... If I listen to the 1176´s outputs while no audio fed in I can hear the pot scrathing when i turn it. I also see it in the VU meters.
 
I've read that people like a product called Deoxit  for pots. CRC might be to harsh for pots and could cause problems. After deoxit use appropriately called faderlube. These products are sold by Caig company.
 
Bobby Baird said:
Anyone have a hairball t-pad that chatters or crackles as you turn it? If so how did you shut them up? This noise makes it impossible to ride the fader on the fly. Should the 3 pins in the center be grounded?

Could have been poorly constructed.  It happens.  Email me and let's get you a new one.

Mike
 
No worries Mike. T-pad on the 1176 works as should when feeding signal from the interface, but only seem to have a chatter problem when feeding it from my bass amp 600 ohm out for some reason. As I can't really ride the fader as I play my bass guitar it shouldn't be an issue. I only hear it as I dial in my input level to the compressor while playing bass. Once it is set signal is fine. It seems to be source specific.
 
Anyone have a hairball t-pad that chatters or crackles as you turn it? If so how did you shut them up? This noise makes it impossible to ride the fader on the fly.


Yes I am having this issue with one now and it hasn't gone away.  Attempting a clean won't be easy since the pads are sealed.    Maybe that's just the way it will be with these?  Anybody have one that doesn't crackle?
 
Bobby Baird said:
T-pad on the 1176 works as should when feeding signal from the interface, but only seem to have a chatter problem when feeding it from my bass amp 600 ohm out for some reason. As I can't really ride the fader as I play my bass guitar it shouldn't be an issue. I only hear it as I dial in my input level to the compressor while playing bass. Once it is set signal is fine. It seems to be source specific.

That sounds like there's DC on it.
 
emrr said:
Bobby Baird said:
T-pad on the 1176 works as should when feeding signal from the interface, but only seem to have a chatter problem when feeding it from my bass amp 600 ohm out for some reason. As I can't really ride the fader as I play my bass guitar it shouldn't be an issue. I only hear it as I dial in my input level to the compressor while playing bass. Once it is set signal is fine. It seems to be source specific.

That sounds like there's DC on it.

Agreed.  Easily checked with a decent multimeter.
 
I'm having the issue with the T-Pad across the OT secondary of a tube preamp.  Not a DC problem in this case.
 
I was able to solve the noise problem.  Apparently it was due to non soldered, mechanical only connections.  I had hand twisted a splice of the wires coming from the T-Pad going to a set of binding posts on the output panel as a temporary connection until the TRS panel jacks arrived.  The connection was adequate and passed signal fine but apparently the T-Pad didn't like it.  After installing the TRS jack and getting everything soldered the rotation noise went away.

Let me repeat that the nature of the noise was - It made lots of small crackling sounds only when rotated and was fine when in place.  Also know that there was no DC present - the T-Pad was connected to the secondary of a transformer so DC is impossible.

So the T-Pad output was seeing a mechanical, non soldered connection downstream and acting up when rotated.  When that downstream connection was soldered in place properly the noise went away.  Again, note that the mechanical connection was twisted tightly and was considered plenty good for checking signal - just like an alligator clip - or like an edge connector card. So it was non faulty for one condition but apparently problematic for another.  Nothing else had changed since the noise was observed.  Mechanical vs soldered contact was the only variable between noisy operation and quiet operation.
 
lassoharp said:
I was able to solve the noise problem.  Apparently it was due to non soldered, mechanical only connections.  I had hand twisted a splice of the wires coming from the T-Pad going to a set of binding posts on the output panel as a temporary connection until the TRS panel jacks arrived.  The connection was adequate and passed signal fine but apparently the T-Pad didn't like it.  After installing the TRS jack and getting everything soldered the rotation noise went away.

Let me repeat that the nature of the noise was - It made lots of small crackling sounds only when rotated and was fine when in place.  Also know that there was no DC present - the T-Pad was connected to the secondary of a transformer so DC is impossible.

So the T-Pad output was seeing a mechanical, non soldered connection downstream and acting up when rotated.  When that downstream connection was soldered in place properly the noise went away.  Again, note that the mechanical connection was twisted tightly and was considered plenty good for checking signal - just like an alligator clip - or like an edge connector card. So it was non faulty for one condition but apparently problematic for another.  Nothing else had changed since the noise was observed.  Mechanical vs soldered contact was the only variable between noisy operation and quiet operation.

You saved me a pile of grief. I removed the noisy comp, removed the top, removed the tinned wire tips and reinstalled the connections downstream to the tranny and then to the board, reassembled and tested good. To know I would have ordered a new pot desoldered and re-soldered to have the same noise would have been frustrating to say the least.
 
You saved me a pile of grief. I removed the noisy comp, removed the top, removed the tinned wire tips and reinstalled the connections downstream to the tranny and then to the board, reassembled and tested good. To know I would have ordered a new pot desoldered and re-soldered to have the same noise would have been frustrating to say the least

Glad to hear it!  Sometimes those little things are the hardest to catch
 

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