[BUILD] 1176LN Rev D DIY

[TreyDay]

Hi,

I'm having problems with this part.

Apply a 1 KHz O dBu signal to the input and confirm with your DMM between pin 2 and 3 of the input XLR.  Now move your DMM to the output XLR and measure AC between pin 2 and 3.  Adjust the output control to read +11dBu (2.75 VAC) on your DMM at the output. Slowly turn the Q-bias adjust (R59) CW until a drop of 1 dB occurs, and your DMM reads +10 dBu (2.44 VAC).  This places your gain reduction FET Q1 slightly into conduction.

Im not getting any measuring out the XLR output.

I  hope anyone could help me.

Regards,
TreyDay

 

[dbonin]

Start at the input before you go any further - do you have an input signal making it to the PCB?  ie signal through the t-pad and through the input transformer?

Thanks!
-Don

Hi,

I'm having problems with this part.

Apply a 1 KHz O dBu signal to the input and confirm with your DMM between pin 2 and 3 of the input XLR.  Now move your DMM to the output XLR and measure AC between pin 2 and 3.  Adjust the output control to read +11dBu (2.75 VAC) on your DMM at the output. Slowly turn the Q-bias adjust (R59) CW until a drop of 1 dB occurs, and your DMM reads +10 dBu (2.44 VAC).  This places your gain reduction FET Q1 slightly into conduction.

Im not getting any measuring out the XLR output.

I  hope anyone could help me.

Regards,
TreyDay

 

[Unit7]

for resistors only

 

[rosestudios]

Hi all, first post here,

I've already searched through here and on the internet, but I'm having trouble with the last step of calibration.  I am using the complete Hairball 1176 Rev D kit and as such I was only given two FETs which I were to assume were matched by hairball.  All other transistors have been tested for appropriate hFEs and the meter transistors are within 5% of each other.

I have already successfully performed the Q-bias and Null set, and I can pass audio through and have audible compression.  However when I am trying to do the gain reduction tracking meter adjustments I can never get more than -6 dB of a difference when engaging gain reduction mode.  I'm applying a 1 kHz signal at 0 dB, I start with my input at 12 and then using +4 mode on the meter I bring the output up to 0 dB and begin my adjustments.  I have seen both the MNATS and DBonin videos for calibration but neither is really pointing me in the right direction and both seem to be able to more effortless perform this calibration then I've been able to.  R44 is in and at nearly no resistance. 

Help would be greatly appreciated, if it's easier to privately message me that's fine too.  Thanks.

 

[AErige]

Hi all, first post here,

I've already searched through here and on the internet, but I'm having trouble with the last step of calibration.  I am using the complete Hairball 1176 Rev D kit and as such I was only given two FETs which I were to assume were matched by hairball.  All other transistors have been tested for appropriate hFEs and the meter transistors are within 5% of each other.

I have already successfully performed the Q-bias and Null set, and I can pass audio through and have audible compression.  However when I am trying to do the gain reduction tracking meter adjustments I can never get more than -6 dB of a difference when engaging gain reduction mode.  I'm applying a 1 kHz signal at 0 dB, I start with my input at 12 and then using +4 mode on the meter I bring the output up to 0 dB and begin my adjustments.  I have seen both the MNATS and DBonin videos for calibration but neither is really pointing me in the right direction and both seem to be able to more effortless perform this calibration then I've been able to.  R44 is in and at nearly no resistance. 

Help would be greatly appreciated, if it's easier to privately message me that's fine too.  Thanks.

Lots of people got the same issue.....try a 5k trimpot for q bias instead of 2k
http://groupdiy.com/index.php?topic=50547.0

 

[dbonin]

Hi all, first post here,

I've already searched through here and on the internet, but I'm having trouble with the last step of calibration.  I am using the complete Hairball 1176 Rev D kit and as such I was only given two FETs which I were to assume were matched by hairball.  All other transistors have been tested for appropriate hFEs and the meter transistors are within 5% of each other.

I have already successfully performed the Q-bias and Null set, and I can pass audio through and have audible compression.

Can you do this for me please and confirm what readings you get:

1.) Apply a 1 KHz, 0dBu signal, confirmed with your DMM at pin 2 and 3 of the input XLR (0.775 VAC).
2.) Move your DMM to pin 2 and 3 of the output XLR.
3.) Set output control for 0dBu (0.775 VAC) at the output.        <----      (My input sits now at 24 and my ouput at the dot between 48 & 36)
4.) Set attack full CCW (off position) set release to 7 or full CW for fast release. Set the Meter to GR mode.
5.) Set input control for +10dBu (2.44 VAC) at your output XLR.        <---------------- NOTE THAT NOW THE ATTACK IS OFF!! (My input sits now at the dot between 24 & 18, and my ouput knob sits between 48 & 36) (Measuring 2.44VAC on my DMM on the output xlr, pins 2/3)

6.) Turn the attack control ON (full CW) and observer the voltage drop at each of the ratio settings

For each of the ratios, on a rev D, you should be seeing something close to this, shown with attack on:
Ratio:
20 (Att On .788VAC)
12 (Att On .679VAC
8 (Att On .642VAC)
4 (Att on .585VAC)

 

[rosestudios]

Will do the above, and thanks for the 5k suggestion I've already requested to receive one just in case.  Will get back to you dbonin, thanks!

 

[Unit7]

I'm building the complete rev D kit. Ready except for HFE matching/soldering the 3708s and calibration of the unit. My only concern so far is that the physical range of the pots (all except the release pot) doesn't match the markings on the face plate. Is this normal?

BTW, Unbelievably nice experience building this kit! Packaging, labeling, build manual all top notch.

Edit: The attack pot is not perfect, but ok, but the input and output knobs only goes up to just past the '6' mark. Am I missing somerthing really silly here?! 

 

[mnats]

I've already searched through here and on the internet, but I'm having trouble with the last step of calibration.

Hmmm...you must have missed the troubleshooting FAQ linked from the first line of the first post of this thread...

 

[Unit7]

Sorry for my eagerness... Just wanted to check if anyone else has the problem I described above - that the physical range of the input/ouput potentiometers don't match the markings on the face plate? Mine stops at just past the '6' mark. I've spent hours searching this thread and the rev A thread and only found one person having this problem, and I couldn't see any replies to his post, so...

 

[dmnieto]

Sorry for my eagerness... Just wanted to check if anyone else has the problem I described above - that the physical range of the input/ouput potentiometers don't match the markings on the face plate? Mine stops at just past the '6' mark. I've spent hours searching this thread and the rev A thread and only found one person having this problem, and I couldn't see any replies to his post, so...

Yes, they do that...

 

[rosestudios]

So update, I've followed hairball's more advanced instructions and properly calibrated the unit and doing the first part of the meter adjustment went perfectly, however when doing the second part in regards to R44, I find that changing the trimpot value is not leading to any results (in regards to having the meter in GR mode).  I hope this doesn't mean the trimpot may have malfunctioned?

 

[Echo North]

So update, I've followed hairball's more advanced instructions and properly calibrated the unit and doing the first part of the meter adjustment went perfectly, however when doing the second part in regards to R44, I find that changing the trimpot value is not leading to any results (in regards to having the meter in GR mode).  I hope this doesn't mean the trimpot may have malfunctioned?

Did you move the shorting plug back?

It's more likely that there is an error elsewhere in the GR meter section.

 

[leitrim_lad]

Hey there, i seem to be having the same problem as treyday.. not getting readings at output..

Getting 0.092v after the transformer.. this normal?

Any help would be greatly appreciated..


leitrim_lad

Hi,

I'm having problems with this part.

Apply a 1 KHz O dBu signal to the input and confirm with your DMM between pin 2 and 3 of the input XLR.  Now move your DMM to the output XLR and measure AC between pin 2 and 3.  Adjust the output control to read +11dBu (2.75 VAC) on your DMM at the output. Slowly turn the Q-bias adjust (R59) CW until a drop of 1 dB occurs, and your DMM reads +10 dBu (2.44 VAC).  This places your gain reduction FET Q1 slightly into conduction.

Im not getting any measuring out the XLR output.

I  hope anyone could help me.

Regards,
TreyDay

 

[leitrim_lad]

Also i seem to be getting a short across R4.. is this normal? Dont seem to be getting any voltage after that point..

Regards

 

[leitrim_lad]

Has anyone else had this problem before? any halp at all would be greatly appreciated.. pulling my hair out checking all res values and everything seems to be good..

 

[dbonin]

Has anyone else had this problem before? any halp at all would be greatly appreciated.. pulling my hair out checking all res values and everything seems to be good..

Hi leitrim_lad,

Can you give a quick rundown on where you're at with the three calibration steps, please?
Am I correct in thinking you are not passing any audio?

Thanks,
-Don

 

[mnats]

Has anyone else had this problem before? any halp at all would be greatly appreciated.. pulling my hair out checking all res values and everything seems to be good..

Checking resistor values is but one thing to try. Of the things listed on the troubleshooting FAQ, what have you tried? The FAQ is meant to be helpful to you, but also gives us a clue as to where the problem may lie.

 

[leitrim_lad]

Hey don thanks fpr getting back to me.. Im on calibration step 1.. iv put on my 1k tone, getting 0.775v on pin 2 and 3 on the input xlr, followed the instructions to a tee (tried both methods) but not getting any voltage on the output pins 2 and 3. my voltage seems to drop to about 0.095v at the point where it connects to the pcb after the input transformer.. I havent passed any audio through it.. havent connected it to the mains yet as i was waiting to calibrate it before i plugged it in.. is this correct?

Thanks

Leitrim_lad

Has anyone else had this problem before? any halp at all would be greatly appreciated.. pulling my hair out checking all res values and everything seems to be good..

Hi leitrim_lad,

Can you give a quick rundown on where you're at with the three calibration steps, please?
Am I correct in thinking you are not passing any audio?

Thanks,
-Don

 

[Harpo]

.. iv put on my 1k tone, getting 0.775v on pin 2 and 3 on the input xlr, followed the instructions to a tee (tried both methods) but not getting any voltage on the output pins 2 and 3.

Between XLR-pins 2/3, not between pin2/0V and pin3/0V.

.. havent connected it to the mains yet as i was waiting to calibrate it before i plugged it in.. is this correct?

??? you can not calibrate/operate it when the unit is not powered. A complaining analogy would be, my car doesn't move though I have not started its engine yet ...