[BUILD] 1176LN Rev D DIY

[kato]

I never tire of seeing finished units.
Beautiful work echo north!

 

[onlymeeee]

Nice build Mike.
What pot did you use for the zero adjust? Did you make the case yourself? How did you do the writing? Lazer engraved?

 

[orangerec]

Nice pair Echo North  ;D
Also, thanks for the JB Weld tip, I can't believe how strong that stuff is. I used it on mounting the pushbuttons and purposely tried to break them but I think you would destroy the switches before breaking the cold weld. Nice meters, are they the Modutecs floating around here or Sifams?

 

[Neeno]

Hi Skylar !
Thank for the nice diagram...

NOTE: there is something I don't get on the attenuator wiring. Double check it.

The input (hot) wire is connected to the wrong spot. In fact following puple schematic it should go to the wiper of the 1st deck, connected to the 620R resistor and not where the two resistor are connected togheter.

 

[Echo North]

[quote author=onlymeeee]
Nice build Mike.
What pot did you use for the zero adjust? Did you make the case yourself? How did you do the writing? Lazer engraved?
[/quote]
Thanks!

Zero adjust: Digikey #SP534-2.0K-ND
I just used the cheapest panel mount multi turn pot I could find.  This one was $13.  Works nice.

Case:
Front Panel Express.  Spendy but high quality.  They are also just down the street so no shipping charges

[quote author=orangerec]
Also, thanks for the JB Weld tip, I can't believe how strong that stuff is. I used it on mounting the pushbuttons and purposely tried to break them but I think you would destroy the switches before breaking the cold weld. Nice meters, are they the Modutecs floating around here or Sifams?
[/quote]

Ha!  I did the same thing!  I was convinced the switches would fly out of their chassis before the weld let go.  I think the key is to not use more then you need and let it dry for a good 48 hours.

It's a Sifam meter but I would have used Modutec if I hadn't already had the hole cut when I saw them.  The original uses Modutec (I think) and they are true VU (I think) so less lag than the Sifams.

Mike

 

[onlymeeee]

13 dollars is a bit more than I'd like to spend really!
How do you think a regular (linear?) pot would work?

As far as I know, it's the other way round. The sifams have less overshoot than the modutecs sold on here.

 

[Echo North]

A regular linear pot would work fine, it would just be harder to dial in "0".  Having 10 turns gives you a lot more accuracy...but at 10X the price...so I understand where you are coming from.

Never used a Modutec,  I'm just interested because they should be like the originals.  I'm also interested in the Hoyt's that Purple uses.

Although the Sifams are a nice meter. 

I'm far from an expert on meters.

Mke

 

[onlymeeee]

Yeh I think I'll try the normal pot and see if it works well enough.  Just thinking off the top my head, maybe there's a way of making a pot less sensitive by putting a resistor in parallel? eg. a 5k pot with a 3k resistor in parallel?)

 

[Skylar]

Hi Skylar !
Thank for the nice diagram...

NOTE: there is something I don't get on the attenuator wiring. Double check it.

The input (hot) wire is connected to the wrong spot. In fact following puple schematic it should go to the wiper of the 1st deck, connected to the 620R resistor and not where the two resistor are connected togheter.

HA! you're right. I think I remember changing this, but I guess I did not update the diagram.

I'll fix this in the PDF. Thanks!

 

[Skylar]

EDIT: duplicate information deleted

 

[Neeno]

You're fast !
But it's still wrong... the wire goes to the wiper (connected to the resistor leg)

 

[Skylar]

!!!!!!!!!!!!!!!!!!!!!!!!!

That's what happens when you work too fast.

But it's still wrong... the wire goes to the wiper (connected to the resistor leg)

Exactly what I meant to do, but somehow that's not what I did!
I'm as confused as you are on why I flubbed it again.

Okay, one more try--thanks for being my editor Neeno!

 

[Skylar]

Okay, it's updated again...see original update post.

 

[Neeno]

Hahahaha !
Now it's right.

Cheers

 

[Stagefright13]

I tried loading Skylar's wiring document and it says the file is damaged and cannot be repaired. Anyone else having a problem?

John

 

[Echo North]

No sir.  Fine here.

Mike

 

[Skylar]

Have you tried right-clicking > save as...
Then save to desktop and open in Acrobat (not your browser)?

If it gives you that error when opening in Acrobat, I would suggest updating Acrobat if possible.

 

[Stagefright13]

OOps that was it. I noticed it worked fine on my other station... Thanks Guys!!

John

 

[JdJ]

Hey all-

Just had to recalibrate my D's (rev1) as the meters (Sifam AL19) had drifted way up to +3 on both channels of my dual mono and on one channel, occasionally didn't seem to be registering GR at all.  No big deal really, set out to re-calibrate but I was using in-the-box metering for the gain reduction measurements etc, and I can not for the life of me get the on-board meters to read 10db of gain reduction?!  I really had to futz with the 0 adjust and the tracking to even get it close.  (I think I recall it being normal for the meter to drop away from zero once the R44 trimmer is re-inserted (after Q Bias & Null adjust)).  I'm getting about -6db on the Sifam with -10db on my Rosetta meters and -10db in the box...  Is there a scale issue with this project on the Sifam meters?  It's not really a BIG deal really,  would just be nice if they were more accurate...

Cheers

J

 

[Stagefright13]

There is no problem with the meter scales. The meter CAN drift up somewhat after extended use as said in the original 1176 manual. That is normal. I calibrate after the unit has been on a few hours. Just follow the video calibration procedures. Then insert R44. then trim the meter as follows:

(This was posted earlier in the thread by Bri but explains it better than I can)

So when you're sure about your Qbias, and have then done the Zero meter, 0volts across R74 step....
Here's an outline of my tracking adjust method...maybe it will help:


R44 in
GRmode(20:1)
Your controls set for the 10db swing(10db of GR)
Your source signal coming through...being compressed.

Now, adjust your meter needle to -10VU using the R44 "tracking adjust" trimmer(reflecting the 10db of reduction).

Now, mute your source signal(or short pad 22 to ground), and adjust the needle back up to 0VU using the "0 Set"(R71) trimmer.

Now un-mute your source signal again(or un-short pad 22), and readjust R44 trimmer so the meter needle again shows the 10db of gain reduction(-10VU).

Mute the source signal(or short the 22 pad), and again use the "0 Set"(R71) trimmer to adjust the meter needle back to 0VU.


You should see a slight bit of change(for the better) after each adjustment cycle.

So, repeat this back and forth adjustment procedure until the meter finally holds it's adjustments...
i.e., the meter needle will eventually hold at -10VU when you have the source signal present, and then go back to 0VU when you mute the source signal(or short pad 22 to ground).
Getting to this point usually requires many repetitions of that adjustment cycle.