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

Help Support GroupDIY:

Deejsirois

Well-known member
Joined
Jun 26, 2018
Messages
50
Okay, I found a hole in my testing regime. The XLR Input +/- terminals ARE shorting to chassis ground when and only when where is a cable inserted and that cable is connected to any other device. I'm going to try removing the jack and making an XLR F pigtail cable to attach to the board, and see what I get.

EDIT: I tried that, and it made no difference, so the issue is definitely somewhere on the board that's beyond. Shipped it to Mike at Hairball today, and I absolutely cannot wait to find out what happened here.
Any word on what you found out? I have the exact same issue.
 

Deejsirois

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Joined
Jun 26, 2018
Messages
50
Does anyone know where to find the voltage chart for the Rev F?

In the absence of a response, I created my own.
 
Last edited:

nbnb

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Jul 10, 2021
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United States
Finished a rack-Rev A and it sounds glorious; however, it seems to be out of phase.

I have checked all the connections from transformers etc - and the input/output XLR's are basically soldered straight to the board (leaving no chance to swap a hot/cold wire). Has anyone else had this issue? If I "Ping" the unit from Logic, it usually gives me a +1 sample latency, but using it as an insert, I have to put a "gain" plugin on the channel to reverse the phase as it comes back in. It's a real bummer.

Any ideas on what to trace, or should I just live with having to flip the phase every time I use the unit? (I hope this isn't the case).
 

Deejsirois

Well-known member
Joined
Jun 26, 2018
Messages
50
Finished a rack-Rev A and it sounds glorious; however, it seems to be out of phase.

I have checked all the connections from transformers etc - and the input/output XLR's are basically soldered straight to the board (leaving no chance to swap a hot/cold wire). Has anyone else had this issue? If I "Ping" the unit from Logic, it usually gives me a +1 sample latency, but using it as an insert, I have to put a "gain" plugin on the channel to reverse the phase as it comes back in. It's a real bummer.

Any ideas on what to trace, or should I just live with having to flip the phase every time I use the unit? (I hope this isn't the case).
swap your cables...been shocked how many times cables have been wired improperly. The other thing to check would be to check to make sure your audio interface doesn't have polarity switched.

And now I am wondering what exactly you mean by "out of phase". How do you know it is out of phase?
 

nbnb

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Jul 10, 2021
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Location
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Thanks for the advice - pretty sure it's not the cables since I used the same two cables on several other outboard units and they have no issues.

And yes, what I meant was polarity (not phase).

If I send a tone to the unit, record the returning signal, and zoom in it's very obvious that the wave forms are opposite each other (polarity). The interface is a UA Apollo and I made sure the polarity switch is off.

Any other ideas? I appreciate any thoughts.
 

dying_star

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Joined
Jan 6, 2022
Messages
1
Location
Nashville, TN
Hey there! I just finished a REV A build and everything seems to be working great except the 4:1 ratio setting. I have to absolutely crank the input to 6+ to get any movement of the meter and audible compression, and by then I've had to turn the preamp down so much and the input on the 1176 up so loud it's got an unusable amount of hiss and noise, or the signal becomes distorted.

Every other ratio works as expected and has been measured to be reducing db as indicated by the meter.

I have checked all of the components on the ratio sub-board and believe them to be correct. I am about 99% sure I installed the 1M R input drop mod, but I can't remember (I tried it with and without when it was still on my bench), and the unit is currently installed in my desk. I've been getting along pretty well at 8:1 but it bugs me the unit isn't working 100%.

Thanks in advance for any strategies to solve this one!
 

Josuebeaucage

New Member
Joined
Apr 28, 2021
Messages
2
Hey there! I just finished a REV A build and everything seems to be working great except the 4:1 ratio setting. I have to absolutely crank the input to 6+ to get any movement of the meter and audible compression, and by then I've had to turn the preamp down so much and the input on the 1176 up so loud it's got an unusable amount of hiss and noise, or the signal becomes distorted.

Every other ratio works as expected and has been measured to be reducing db as indicated by the meter.

I have checked all of the components on the ratio sub-board and believe them to be correct. I am about 99% sure I installed the 1M R input drop mod, but I can't remember (I tried it with and without when it was still on my bench), and the unit is currently installed in my desk. I've been getting along pretty well at 8:1 but it bugs me the unit isn't working 100%.

Thanks in advance for any strategies to solve this one!
You should also check all soldering on the 4:1 resistors circuit (look them up on the diagram), check for continuity and bad solder joints. Also test the all buttons in mode to see how it behaves (I think this mode bypasses all resistors directly to the fet)
Cheers !
 

Bart_J86

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Joined
Jul 13, 2020
Messages
10
Location
Nijmegen
Hi all,

I've build a 1176 Rev D V2 some time ago and the unit is working fine. I would actually really like to add a (true) bypass switch, preferably on the front panel. Since I'm not good at electronics I'm in doubt whether to use a relay based switcht, or just an ordinary switch for this purpose. Which option would you choose and what are the pros/cons for either? I can't seem to find any substantive info on this topic on here.

If the choice would be to use a relay based switch, are there any pre made PCB's for this purpose, or some kind of schematic, as I'm not smart enough to come up with this stuff myself..

If the choice would be to use a non-relay switch, would it be wise to add wire just for this switch to be mounted on the front panel or would this introduce noise/hum or even degrade the overall quality of the signal?

Cheers!
 

surtronomer

New Member
Joined
Jan 16, 2022
Messages
1
Location
Los Angeles
Hello Everyone. Building my first 1176 Rev A. It’s been a blast so far.
Finished the power section build and started to test.
I’m Very happy with the build so far, it’s coming together nicely.

i had one mishap and installed the wrong diode for CR9. After realizing my mistake I pulled it out and replaced it with the one I believe is the correct one. I had a horrible time getting the first diode out and the new one in. Wasn’t able to completely clear the old solder from the through hole… Looks shitty compared to how clean everything else is.

I powered up the unit and began to test. No sparks, or smoke when turned on. I did get some sparks when metering CR8.
30VDC at CR8
-40VDC at CR9!!

Anyone have any idea what it could be? Fried CR9 diode? I don’t have a meter that tests diodes unfortunately but will order one. Something not making contact. Checked grounding at the right side of CR9 and it’s fine.

please help!
thanks in advance!!
Jeremy
 

Deejsirois

Well-known member
Joined
Jun 26, 2018
Messages
50
Hello Everyone. Building my first 1176 Rev A. It’s been a blast so far.
Finished the power section build and started to test.
I’m Very happy with the build so far, it’s coming together nicely.

i had one mishap and installed the wrong diode for CR9. After realizing my mistake I pulled it out and replaced it with the one I believe is the correct one. I had a horrible time getting the first diode out and the new one in. Wasn’t able to completely clear the old solder from the through hole… Looks shitty compared to how clean everything else is.

I powered up the unit and began to test. No sparks, or smoke when turned on. I did get some sparks when metering CR8.
30VDC at CR8
-40VDC at CR9!!

Anyone have any idea what it could be? Fried CR9 diode? I don’t have a meter that tests diodes unfortunately but will order one. Something not making contact. Checked grounding at the right side of CR9 and it’s fine.

please help!
thanks in advance!!
Jeremy
R81 and R82 are responsible for dropping that voltage down to -10, so I would assume that is the issue. Are they properly soldered?
 

Deejsirois

Well-known member
Joined
Jun 26, 2018
Messages
50
I have discovered that on the Rev F, the nuts that hold the output transformer in place if tightened too much can actually cause a short. Hopefully this saves others some time.
 
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