[BUILD] 1176LN Rev D DIY

[canidoit]

Good question. I have never tried it with an unbalanced connection before. Maybe I have the same problem as well.

Have you got a pre-amp with balanced outs? For the meantime, you could plug your synths into a preamp to convert it into a balanced signal for your 1176.

 

[Futureman]

Good question. I have never tried it with an unbalanced connection before. Maybe I have the same problem as well.

Have you got a pre-amp with balanced outs? For the meantime, you could plug your synths into a preamp to convert it into a balanced signal for your 1176.

It seems to work fine with unbalanced inputs. It's when I connect the output of the 1176 to something using an unbalanced jack lead from my patch bay is when the weirdness happens. (Effectively shorting the Cold to Ground)

I remember reading someone saying that their 1176 did not like unbalanced inserts etc.

Thanks for your input!

Regards
Mike

 

[canidoit]

Good question. I have never tried it with an unbalanced connection before. Maybe I have the same problem as well.

Have you got a pre-amp with balanced outs? For the meantime, you could plug your synths into a preamp to convert it into a balanced signal for your 1176.

It seems to work fine with unbalanced inputs. It's when I connect the output of the 1176 to something using an unbalanced jack lead from my patch bay is when the weirdness happens. (Effectively shorting the Cold to Ground)

I remember reading someone saying that their 1176 did not like unbalanced inserts etc.

Thanks for your input!

Regards
Mike

OIC, so its the balanced outs. Maybe the output transformers need to be wired differently for unbalanced connections. I have gear that has separate xlr balanced outs and separate jacks unbalanced outs. Maybe you have to do it with these units. Have a separate unbalanced outs at the back of your unit that is wired differently from the balanced outs.

 

[emrr]

It's not that it's unbalanced; it's transformer isolated so that in of itself doesn't matter.  It's indicative of a grounding issue with either input or output, likely output.  I have seen this with various limiters, tube and SS, and it never really makes sense on the surface.  Experiment with your in/out grounding and see if you lose the problem. 

 

[Futureman]

It's not that it's unbalanced; it's transformer isolated so that in of itself doesn't matter.  It's indicative of a grounding issue with either input or output, likely output.   I have seen this with various limiters, tube and SS, and it never really makes sense on the surface.  Experiment with your in/out grounding and see if you lose the problem.   

So, does that mean that I have made some fault in my wiring (Grounding) of my 1176? Or is this just how the 1176 does behave in my scenario? (Cold output tied to ground)

Thanking you for your insight.
Regards
Mike

 

[emrr]

It's not normal for the 1176.  It could be any of your grounds, and they way they interact with one another, or the outside world.  Something about the act of grounding one side of the output transformer is creating an oscillation that shouldn't be there, and ground is the path.  Somewhere.  Try everything; even reverse both your input AND your output xlr pins 2 and 3 and see if it behaves better. 

 

[Kamel]

as emrr says the ground inside the 1176 is needed to be carefully tied, and use unbalanced input or output short the ground circuit with the outside world, another issue is the input of the 1176 is 600 Z due to the T-Pad, maybe your unbalanced gear can't drive such a low Z.

 

[fallout]

* removed dumb question * 

 

[Futureman]

It's not normal for the 1176.  It could be any of your grounds, and they way they interact with one another, or the outside world.  Something about the act of grounding one side of the output transformer is creating an oscillation that shouldn't be there, and ground is the path.  Somewhere.  Try everything; even reverse both your input AND your output xlr pins 2 and 3 and see if it behaves better.   

Cheers! I'll re-check my earthing. (And swap the polarity of the output)

I thought I was being very careful about my grounding, All shields are grounded to the chassis from one point, as is the Earth.

I'll report back with my findings.

Your help is appreciated!
Regards
Mike

 

[Futureman]

AH!

I have built 3 units so far an believe or not they all behave the same.

Then today I tried to swap pin 2 and 3 at the output transformer (IE= pin 2 is Blue and pin 3 is red) and at the input (for phase consistency).
guess what?

oscillation is gone.
now questions:

-how many people in EUROPE have built this unit, I mean how many have used the "standard european configuration" pin 2 being hot and pin 3 being cold using hairball 5002 trafo? Am I the only one?

-why did it mis-behave like that?If I understand correctly there is a form of negative feedback going back into (or from) the transformer in the output stage, what could happend if the output polarity is reversed?Would that become POSITIVE feedback and therefore generate instability?


I will conduct more tests tomorrow just to make sure I haven't foreseen anything but the baby seemed stable.


Best,
Mattia.

BING!

same problem!

This looks promising!

 

[dmp]

I noticed that the rev D schematic on the Waltzing Bear site does not have R10, the resistor in series with the FET. It looks like that resistor sets a max gain reduction in the FET voltage divider.  So, with R10 the max gain reduction is ~10dB, without ~30dB. Does anyone know when this resistor was added and why? To limit max GR? The Purple Audio & G1176 have this resistor also.

 

[mnats]

I noticed that the rev D schematic on the Waltzing Bear site does not have R10, the resistor in series with the FET.

That schematic posted at Waltzing Bear and listed as "Urei 1176LN series D, "Black face", single ended class A output" isn't what it says it is and the difference isn't just R10. The two BJT first stage and lack of the LN circuitry suggests it is the weird Revision B model and the only major revision I haven't attempted.

Why not give it a try and tell us what you think?

 

[pacemaker]

Hi guys,
i have rechecked my grounding,
changed output transformer polarity,
but i still have oscillations,
i am in the painfull situation of being stucked
any leads to start troubleshooting
would be greatly appreciated.
Regards,
Francois

 

[dmp]

Thanks mnats, the waltzing bear schematics had me confused yesterday. The UREI-1176LNmanual.pdf has the most historically correct, I take it.
I was observing yesterday that the compression in my rev D returns to 1:1 after about 10-15dB of reduction, after the FET divider is maxed out. Might be that this returns some dynamics to peaks under heavy compression. I'd like to build a revA and compare, since the rev A just has the FET as the leg of the divider.

 

[guitarguy12387]

Hey guys,

So i wired up my first pushbutton rev. d today (built a few rev js) and i get some pretty loud distortion. Using altran and Ed andersen trannys.

Basically everything is distorted... speech is inaudible. Even with GR bypassed, i get distortion. Any ideas?

A few questions that i made assumptions about and i wanna make sure i am right:

The input pad on the main board (mnats rev. 2) has a + and Gnd pads. Going from skylar's wiring image/guide thingy, it says '+' and '-' ... i assumed gnd is '-' correct?

Also, there appears to be other GND pads on the board near wires that require shielded wire that, according to skylar's guide, are N.C. I assumed that i am supposed to take the shield to those gnd pads, right?! For example, pad 7, i have a 1 conductor shielded wire going from pad seven and i take the shield to the gnd pad next to pad 7 on the main board and the other end of the shield (at the release knob) is not connected to anything. Is this correct?! (sorry if this is an unclear description).

Lastly, i have found that Q6 (2n3053) gets very hot. I saw this mentioned before, but couldn't find any conclusions... do i need a heatsink? If i do need a heatsink, how do you attach heatsinks to TO39 package?? Will i need to replace Q6?

Thanks in advance!!

 

[fallout]

The input pads on the main PCB would be connected to the +/- coming from the input transformer's secondaries. So - from the transformer would go to the input pad marked gnd.

The shield on the wire going to pad 7 is not connected on either end on Skylar's diagram although connecting it on just one end shouldnt mess anything up.

http://www.mouser.com/ProductDetail/Aavid-Thermalloy/578305B00000G/?qs=2v7q0MSBcBMVIGpeoAPVAQ%3d%3d

The heatsink above just slips over Q6.

Hope this helps..

-jay

 

[guitarguy12387]

Okay thanks!

Hmmm so i wonder where the distortion is coming from...

I'll check all my wiring/connections again.

 

[SaMpLeGoD]

Hello all, I builded 2 RevD, 1 Rev F and 1 Rev A, and I was just wondering why especially in Rev Ds, the Vu's needle never stay at the 0 on GR. I regulate that once, use the comp that works fantastic and the needle stops at 0, but after a while without using it, the needle goes slightly to the left and after that, pass by 0 again and stay slightly to the right, and vice versa... never stays still at 0 for like a session. That doesn't occur on the Rev A. It stays still all the time since regulated...
I thought that it happens when you have some dirt around the Fets, but at this moment I have some doubts... any idea?

Cheers,

Eddie

 

[canidoit]

Hello all, I builded 2 RevD, 1 Rev F and 1 Rev A, and I was just wondering why especially in Rev Ds, the Vu's needle never stay at the 0 on GR. I regulate that once, use the comp that works fantastic and the needle stops at 0, but after a while without using it, the needle goes slightly to the left and after that, pass by 0 again and stay slightly to the right, and vice versa... never stays still at 0 for like a session. That doesn't occur on the Rev A. It stays still all the time since regulated...
I thought that it happens when you have some dirt around the Fets, but at this moment I have some doubts... any idea?

Cheers,

Eddie

I asked the same question as well. But someone informed me that it is natural with the Rev D and even occurs on the original Rev Ds, like the Urei. I don't know if this is true though.

I don't know if the UA 1176 re-issues have this problem, but I now that the UA LA3a does not have any wandering VU needles issues.

 

[SaMpLeGoD]

I asked the same question as well. But someone informed me that it is natural with the Rev D and even occurs on the original Rev Ds, like the Urei. I don't know if this is true though.

I don't know if the UA 1176 re-issues have this problem, but I now that the UA LA3a does not have any wandering VU needles issues.

Ok, I don't know about the original too... but if it seems to be a known problem, that's ok the important is that the Rev D sounds great! forget the needle
Thanks for replying
Cheers,

Eddie