Blog Pages

6/29/13

1176 CLONE COMPLETE

FIRST POWER UP

Meter glowing with no smoke showing, looks like we are good to go!

With no obvious way to connect power to the meter lamp I used a large value power resistor to drop the voltage down from the unregulated voltage to 12V.

The resistor gets a bit warm but I don't care. The heat reminds me of vacuum tubes so that's o.k....


REFERENCE SCHEMATIC

When you build any type of kit you should always have an accurate schematic to reference.

I used a copy of the original UREI Rev D that I downloaded from the JBL Pro Audio site.

It's a huge reference manual filled with 1176 information. Thank you JBL!

 




CIRCUIT BOARD CARNAGE

I cut and I jumped and I blew this board apart. I dug into this circuit board so much that it looked like a hurricane hit it after I was done!
 
My goal was to make real AC and DC measurements during the build process.
 
Everything will be posted here eventually so keep checking back. I will be documenting my next 1176 build as well. I am planning that build for 2014.
 
 

GAIN REDUCTION RECTIFIERS

Measuring the output of the rectifier stage definitely surprised me.
 
It is not even close to what SPICE had predicted.
 
I need to go back and see what's going on. Either my model is crap or my circuit build is crap but most likely not both.
 
 

MAXIMUM OUTPUT

Measuring the output showed about a 20 volt peak output before clipping.
 
That's 40Vpk-pk ! You're not going to be slamming that into your DAW.
 
We'll, not without extreme converter clipping....
 
 

1176 KIT FIT & FINISH

Overall the Hairball Audio Revision D kit totally rocks. It is definitely not a kit for absolute beginners but those with some build experience should be able to push through it.
 
There were a couple of issues that could have been better though: For example, the output transformer wires didn't reach the XLR jack and the power transformer wires wouldn't reach the PCB if it was located at the other side of the enclosure.
 
Not huge issues, but rather final touches that would have made the build go a bit smoother.
 
Again, this kit is a great deal. I think the total build cost for me was around $600.
Remember though, these kits aren't going to perform like the real deal. So don't expect it to!
 
 

TEST CONNECTORS

Both inputs and output connections on an 1176 are balanced. This is the way Pro Audio gear is designed!
 
However, balanced XLR connectors make it very difficult to connect to standard electronics test equipment which is typically un-balanced.
 
What makes testing a breeze are XLR to 1/4" adapters. I picked these up at a local San Diego electronics supply store.
 
They cost about $10 ea. But, they make testing so much easier that it is totally worth the investment. You will need one XLR-M and one XLR-F type adapters.
 

 
That's it for now. As I go through my images of the build I will post them here.
 
There's a lot more to come so please stay tuned.
 
Thanks for reading!
Trenton