[BUILD] New FET/RACK Official Help Thread - Please read first post!

[Spaceyjb]

That's impedance loss.  Just boost your signal till you see 0dBu.

Funny thing. I had to push my generator to about 3,4 dBu and now when i try to set output knob in step 3 calibration to read 0dB/0.775V it is really hard to do as output oscilates in between 0.775-.774V (-0.03 and -0.11dBu)

EDIT: Fully calibrated and does not oscilates...

EDIT: checked voltages at TP21/22/CR2+  about the same...

 

[Echo North]

Funny thing. I had to push my generator to about 3,4 dBu and now when i try to set output knob in step 3 calibration to read 0dB/0.775V it is really hard to do as output oscilates in between 0.775-.774V (-0.03 and -0.11dBu)

EDIT: Fully calibrated and does not oscilates...

EDIT: checked voltages at TP21/22/CR2+  about the same...

Same issues?

 

[Spaceyjb]

Same issues?

EDIT: After studio test: unfortunately the problem is persisting. What has definitely change for better is character of the distortion. It is much more pleasant, but as soon as I set input knob so to compression start level it starts to distort. it seems attack / release knobs has not any influence with exception of bypass, so the time is super super fast at all circumstances and maybe that is the reason of distortion... I will check there.

Jan



audibly it is much better... lesson made.  I would not say I shouldn't use professional generator/analyzer gear to calibrate... I still feel there is something weird with transients, but i need to do preper tests in the studio.
Do you think it would make sanse to set qbias just slightly softer: not for 1dB loss but maybe 0.7 and the beast would be a bit softer on these transients. Or should I have a look on attack/release and ratio boards?

But what I do not get is, how the hell it just drifted to the distorted state after couple weeks of normal operation... there must be something wrong with my soldering job. I mean these ground points are pretty hard to solder. even with paste and a bit higher temperatures i had really hard time to solder them to board properly. Could it be the reason? I checked them all and measured resistance and they seem ok. I just love your builds as I really learn so much

anyways thanks a million for your help. I will let you know the final resume.

Jan

 

[Jacob123588]

ok so got the input to read .775, now getting nothing on the output. I'm getting a 0.000 reading. and to get sound I have to crank the input of my returning input al the way! what could be the issue? Thanks

 

[Spaceyjb]

Hi Mike,

could it be faulty R56 (Release pot?). I found out one of its legs is broken. I soldered it out and now I am looking for subtitute as mouser doesn't have them stocked. And I have quite hard time. Is there any chance you can sell me one?

Thanks

Jan

 

[mrbobbailey]

Greetings

I've finished 2 FET/Rack Bluestripes and calibrated to what I thought was success.  Q Bias set, and the GR Meter measuring properly at 0 and a 20db drop when loaded with signal.  When I put the top plate on and packed it into the rack, however, both VU meters read roughly +1db. 

When I took one back out of the rack and removed the top plate, I discovered my VU meter on that read 0db again.  What is causing this?

Thanks in advance,

Bob B

 

[Echo North]

Hi Mike,

could it be faulty R56 (Release pot?). I found out one of its legs is broken. I soldered it out and now I am looking for subtitute as mouser doesn't have them stocked. And I have quite hard time. Is there any chance you can sell me one?

Thanks

Jan

Absolutely could be your issue. Send us an email.

 

[Echo North]

ok so got the input to read .775, now getting nothing on the output. I'm getting a 0.000 reading. and to get sound I have to crank the input of my returning input al the way! what could be the issue? Thanks

Ya your signal isn't making it through the circuit.

Set your unit to:
Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR OFF
Release: Full CW
Ratio: 20:1
Meter: GR
Signal: Sine 1kHz @ 0dBu

With your DMM measure your AC at the following test points using the chassis as you reference (black probe).

-Input XLR +
-TP1
-TP15
-TP17
-Output Transformer BRN
-Output XLR +

 

[Echo North]

Greetings

I've finished 2 FET/Rack Bluestripes and calibrated to what I thought was success.  Q Bias set, and the GR Meter measuring properly at 0 and a 20db drop when loaded with signal.  When I put the top plate on and packed it into the rack, however, both VU meters read roughly +1db. 

When I took one back out of the rack and removed the top plate, I discovered my VU meter on that read 0db again.  What is causing this?

Thanks in advance,

Bob B

The VUs are prone to drift with heat, that why the have the 0 adjustment on the front panel. But what you're describing sounds weird. I could see popping the panel on would cause heat to build faster and change the meter.

Do the units work and sound good?

Maybe pop it in with the lid on, let it sit for a while and set the zero. See how it sounds. Keep in mind when you tuen it off and cool it down, when you restart the meter will probably start at -1dB, then over an hour or 2 of use will creep back to 0.

Mike

 

[Jacob123588]

Ya your signal isn't making it through the circuit.

Set your unit to:
Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR OFF
Release: Full CW
Ratio: 20:1
Meter: GR
Signal: Sine 1kHz @ 0dBu

With your DMM measure your AC at the following test points using the chassis as you reference (black probe).

-Input XLR +
-TP1
-TP15
-TP17
-Output Transformer BRN
-Output XLR +

-Input XLR + -- 0.775
- TP1 -- 0.137
- TP15 -- 0.010
- TP17 -- 0.000
- Output Transformer BRN -- 0.033
- Output XLR -- 0.000

 

[exfakto]

Hi There,

I just finished building a FET Rack Revision A and everything went pretty smooth. During calibration, the meter was working perfectly. When I was almost done with the calibration, all of a sudden the meter stopped reading in GR mode. It works fine on +8 and +4 but just drops completely to the left and does not move on GR more. I can hear the signal being compressed but to the gauge. I've spent a good 4 hours yesterday trying to figure it out with no success. Please help.

Thanks

 

[Echo North]

-Input XLR + -- 0.775
- TP1 -- 0.137
- TP15 -- 0.010
- TP17 -- 0.000
- Output Transformer BRN -- 0.033
- Output XLR -- 0.000

Your signal is dying  between TP1 and TP15.

This stuff is in the box labeled "Signal Preamp" in the lower corner. Check all of your components and soldering there including the output pot soldering.

Mike

 

[Echo North]

Hi There,

I just finished building a FET Rack Revision A and everything went pretty smooth. During calibration, the meter was working perfectly. When I was almost done with the calibration, all of a sudden the meter stopped reading in GR mode. It works fine on +8 and +4 but just drops completely to the left and does not move on GR more. I can hear the signal being compressed but to the gauge. I've spent a good 4 hours yesterday trying to figure it out with no success. Please help.

Thanks

You might have a wonky solder joint in your GR control amp section or on your meter switch. Try reflowing those parts.

If that fails, check your DC voltages in the GR control amp:
http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

It's called GR Meter Driver in that PDF.

Mike

 

[Diamondj421]

Hey Mike
So both 1176s that I have have been up and running for a few weeks now. They sound so good. Only issue I'm having still is with the stereo links. I've been having to run them in dual mono mode because they don't seem to work when I switch them to stereo. I'm turning both stereo links on, setting one to send and one to receive but at that point one units  suffers from a fairly drastic signal reduction.  So if they're set up as L/R in Mono mode, they're reading at the same level on my DAW's meter but once I activate the link, the left channel drops by about 7dB. The left unit's meter while set to GR maxes out while the right continues to function as expected. That being said, I'm getting the left unit is applying more compression. Is this user error or is there something going on here? I've tried changing the settings as described on the link build page but nothing seems to change. Thanks!

 

[Echo North]

Hey Mike
So both 1176s that I have have been up and running for a few weeks now. They sound so good. Only issue I'm having still is with the stereo links. I've been having to run them in dual mono mode because they don't seem to work when I switch them to stereo. I'm turning both stereo links on, setting one to send and one to receive but at that point one units  suffers from a fairly drastic signal reduction.  So if they're set up as L/R in Mono mode, they're reading at the same level on my DAW's meter but once I activate the link, the left channel drops by about 7dB. The left unit's meter while set to GR maxes out while the right continues to function as expected. That being said, I'm getting the left unit is applying more compression. Is this user error or is there something going on here? I can't seem to find anything posted about the links on here. Thanks!

Did you read the link user guide at the end of the link build guide?  Also are you FETs reasonably matched? Did you buy the units at the same time?

 

[Diamondj421]

Did you read the link user guide at the end of the link build guide?  Also are you FETs reasonably matched? Did you buy the units at the same time?

Not sure about the FETs being matched. I actually damaged my PCB trying to correct the FETs on my second build and had to send it in to you to fix if you recall. They were not both purchased at the same time.

 

[Diamondj421]

Not sure about the FETs being matched. I actually damaged my PCB trying to correct the FETs on my second build and had to send it in to you to fix if you recall. They were not both purchased at the same time.

But yes, did read the end of the build guide. Changing the four settings don't seem to make a difference.

 

[Echo North]

Not sure about the FETs being matched. I actually damaged my PCB trying to correct the FETs on my second build and had to send it in to you to fix if you recall. They were not both purchased at the same time.

Your FET's don't need to be stereo matched, but they need to be reasonably matched.

Think you could get 2 new sets in if we sent them to you?

 

[Diamondj421]

Your FET's don't need to be stereo matched, but they need to be reasonably matched.

Think you could get 2 new sets in if we sent them to you?

While mildly terrified, I feel up to the task! Should I just shoot you guys an email?

 

[Echo North]

While mildly terrified, I feel up to the task! Should I just shoot you guys an email?

Yup.