[BUILD] 1176LN Rev D DIY

[audiophreak]

Note: it's usually better to put something aside when frustration starts to get the better of you. Come back to it later with a clear head and things will go more smoothly.

  I'm out more than home these days and my work bench is a total mess ... gonna put this one aside for now , clean the work bench and my head.
  My OCD wont let me give up , I will continue , as stated above  ... I'll live to fight another day  \m/

 

[studiostuff]

Received my Rev. D with a Blue Stripe enclosure in five days from Mike. Fast!! Everything looks great, thanks.

Someone explain how come it takes five days for the PCBs from MNATS in OZ to get to Dallas and five days for the enclosures and whatnot from Mike to get to Dallas...?

Are they the same distance? Should we redraw maps from a delivery time POV...? 

 

[kiopo]

From the schematic I think it's fine too but it's a little hard to follow with the switch pinouts etc. I

For anyone else interested, here's an idiots guide to DPDT wiring  : http://www.diystompboxes.com/pedals/articles/elbypass.html

Didn't realise it was that simple, makes troubleshooting those parts of the circuits a lot easier.

Also, top tip, don't leave putting the meter in until near the end  . Pretty fiddly.

 

[LHS]

Just finished my wiring everything and now I'm moving on to calibration. I don't want to twist the Q bias trim pot into breaking. Before installing all the trim pots I used the DMM to roughly "center" the wiper. In the mnats Q Bias calibration video he says to move the wiper all the way to the side allowing the maximum sound through.

How can I make sure I've gone as far as the pot will go without breaking it? I twisted it until it seemed to respond less to adjustment and seemed as if I might have been close to breaking but I'm sure there must be a more exact way to confirm this?

Also, regarding video three (gain reduction meter adjustment), I'm confused about when to use the R44 jumper vs. when to use the attack off. I looked at previous posts and it seems some people have said to be sure the jumper is in place for this step while mnats video says to use the attack knob instead of the jumper. Which is it?

 

[dbonin]

Just finished my wiring everything and now I'm moving on to calibration. I don't want to twist the Q bias trim pot into breaking. Before installing all the trim pots I used the DMM to roughly "center" the wiper. In the mnats Q Bias calibration video he says to move the wiper all the way to the side allowing the maximum sound through.

How can I make sure I've gone as far as the pot will go without breaking it? I twisted it until it seemed to respond less to adjustment and seemed as if I might have been close to breaking but I'm sure there must be a more exact way to confirm this?

Also, regarding video three (gain reduction meter adjustment), I'm confused about when to use the R44 jumper vs. when to use the attack off. I looked at previous posts and it seems some people have said to be sure the jumper is in place for this step while mnats video says to use the attack knob instead of the jumper. Which is it?

Watch my videos - I cover your questions in video 1 and 3 - as for the r44 jumper, that's the three pin header on the board - it has to be in place to complete the third calibration.

http://www.youtube.com/watch?v=0Uuk1Y7M2D8
http://www.youtube.com/watch?v=lRStwXwmBUw
http://www.youtube.com/watch?v=pgSWfsEzU40

Cheers!
-Don

 

[kiopo]

Just finished my wiring everything and now I'm moving on to calibration. I don't want to twist the Q bias trim pot into breaking. Before installing all the trim pots I used the DMM to roughly "center" the wiper. In the mnats Q Bias calibration video he says to move the wiper all the way to the side allowing the maximum sound through.

How can I make sure I've gone as far as the pot will go without breaking it? I twisted it until it seemed to respond less to adjustment and seemed as if I might have been close to breaking but I'm sure there must be a more exact way to confirm this?

Also, regarding video three (gain reduction meter adjustment), I'm confused about when to use the R44 jumper vs. when to use the attack off. I looked at previous posts and it seems some people have said to be sure the jumper is in place for this step while mnats video says to use the attack knob instead of the jumper. Which is it?

Watch my videos - I cover your questions in video 1 and 3 - as for the r44 jumper, that's the three pin header on the board - it has to be in place to complete the third calibration.

http://www.youtube.com/watch?v=0Uuk1Y7M2D8
http://www.youtube.com/watch?v=lRStwXwmBUw
http://www.youtube.com/watch?v=pgSWfsEzU40

Cheers!
-Don

Great videos, thanks, I'll definitely reference these when I get up to calibrating mine too. So basically, you just turn the wiper until it gets stiff?

 

[kiopo]

Hello everyone,

I got my potentiometers today (thank you Mike!) and finished my build, all working great . Calibration wasn't as awkward as I expected!

Sounds lovely, exactly what you want from an 1176 and reacts almost identically to how I remember the ones that I've used. Such low noise as well, kudos for all the wiring tips.

What is the best way to verify the ratios are working as they should? It all sounds right to me but wouldn't mind having a look. My DMM is useless at low VAC, but I can work with test tones and record them back in etc..

Thanks again to Mike, mnats and everyone else involved in putting this together. Was a lot of fun to build and learnt a lot.

What to build next?  8)

 

[Trench Recordings]

Careful kiopo. You're in danger of becoming addicted to DIY. There is no cure...

 

[sr1200]

bankruptcy helps....  ;D ;D ;D

 

[ln76d]

bankruptcy helps....  ;D ;D ;D

;D ;D ;D ;D

Yeap, you are right. Right now i'm on the way of it  ;D ;D ;D

 

[LHS]

I'm using a signal generator out of pro tools out of my lynx DA converter. At -20.3db on the signal generator I can get .777V from pin 2 and 3 of my input. Is that close enough to .775V?

Also, when I move my front panel input knob up from off to all the way up I measure a voltage drop of around .030V at pin 2 and 3 of my input. Normal?

 

[dbonin]

I'm using a signal generator out of pro tools out of my lynx DA converter. At -20.3db on the signal generator I can get .777V from pin 2 and 3 of my input. Is that close enough to .775V?

Also, when I move my front panel input knob up from off to all the way up I measure a voltage drop of around .030V at pin 2 and 3 of my input. Normal?

That's plenty close.  The voltage drop is normal.

 

[LHS]

Huge thanks to mnats hairball and dbonin. Unit is fully calibrated and works beautifully. Looking forward to a rev A in the future.  8)

 

[kiopo]

One basic thing I forgot to do was wait until the unit was fully warmed up to calibrate it, around 30 mins. GR meter 0 position will raise if you do it earlier than that!

 

[morls]

Hello,
I'd like to ask for some advice please...
I'm building my second 1176 rev. D, and have run into a problem. When I turn the unit on, set to GR, the VU meter goes off the scale to the right. There is also no signal passing through. When in +4 or +8 mode the meter is fine, i.e. no signal reading.

I've checked all the transistors and caps to make sure I haven't put anything in the wrong way. I've also gone back and re-wired the ratio, attack and release pots and meter board connections, but no joy as yet.

I also checked the voltages, and there is something weird happening at the transistors. From the rev. D schematic with voltage there are 3 readings for each transistor - (I'm unsure of the technical terms for each leg, so I'll refer to them as top, middle and bottom, as per the circuit diagram). Here's what I get:
At Q9 - top leg = 2.78V; middle leg = 16.36V; bottom leg = 3.37V
At Q7 - top leg = 4.35V; middle leg = 14.58V; bottom leg = 3.8V
It seems to me that the voltages for the top and middle legs are somehow crossed, or swapped. This is consistent across transistors Q7, Q8, Q9, Q10, Q12, Q13.
The voltage at R87 = 27.07V; at CR6 it's -9.7V

Can anybody offer any advice please?

Thanks

Stephen

 

[morls]

Hello,
I appear to have solved the issue. After much head scratching and testing I built Mark Burnley's DIY signal tracer via the link on the excellent mnats FAQ page. It turns out the problem was in the Input Transformer, a bad connection via the 2-pin headers. After removing these and connecting directly to the PCB the signal passed nicely.
Thanks mnats for the great FAQ.
Stephen

 

[kiopo]

Hello,
I appear to have solved the issue. After much head scratching and testing I built Mark Burnley's DIY signal tracer via the link on the excellent mnats FAQ page. It turns out the problem was in the Input Transformer, a bad connection via the 2-pin headers. After removing these and connecting directly to the PCB the signal passed nicely.
Thanks mnats for the great FAQ.
Stephen

Interesting, hopefully the headers don't present a problem with bad connections over time.

And by the way, my meter does a little dance on turn-on as well (but not in GR mode). I assume it's normal.

 

[morls]

Interesting, hopefully the headers don't present a problem with bad connections over time.

I think it's more likely to have been a fault of my wiring than of the header. I was having trouble getting good contact with a few others as well...

 

[mrtomcat]

Question:
I just finished the Rev A and am working on a Rev D now, but there is an additional trimmer in the Preamp Section that the Rev A does not have nor is that mentioned in any of the Rev D Calibration videos...
What is that one for? and is there any more info on this?
I did a search on here but not much luck

 

[Echo North]

Question:
I just finished the Rev A and am working on a Rev D now, but there is an additional trimmer in the Preamp Section that the Rev A does not have nor is that mentioned in any of the Rev D Calibration videos...
What is that one for? and is there any more info on this?
I did a search on here but not much luck

Distortion trimmer.  You need something that measures THD which most people don't.  I have something that measures THD and this trimmer doesn't do a whole lot.  Set it in the middle.

You might be able to find some free THD measuring software.  If so feed a 500Hz signal @ -30dB in bypass.  Set your input/outptut 3/4 max and trim for lowest THD.