All things G1176 - the new "repost" thread.

[gswan]

Can someone please explain what the "CP" stands for on my IC's and if it will be OK to use these TL071CP instead of TLO71?

C = commercial temperature range
P = plastic DIP package

A TL071CP is a TL071

 

[jrfred453]

Hey guys I'm a little stuck on my dual G1176 build. First channel is working great. Second channel passes audio but no compression.
I checked the voltages and it gets way off at Q12-Q15. I get 5.43, 5.87, and 20.41 at Q12 and it gets worse from there on.
These are in the gain reduction amp right? I could really use some help finding my problem. Thanks.

 

[gswan]

If your DC bias conditions are off it's time to check resistor values and transistor orientation.
Check R60, 61, 62 first, around Q12.

 

[mac]

Apologies if this has been dealt with, (i am only up to page 75 in reading this rather long thread). I am about to commence my dual 1176 build on Mnats boards, Rev J.

I am planning on going Ne5532 input and OEP output for starters, but might want to change to Lundahl input later. How involved is the change over? Is it as simple as just changing my inputs on the two boards and installing the Lundahl LL1540? Or is there some components that I would need to remove from the board to take the input section out of the circuit?

Thanks, Mac.

 

[Biasrocks]

I am planning on going Ne5532 input and OEP output for starters, but might want to change to Lundahl input later. How involved is the change over? Is it as simple as just changing my inputs on the two boards and installing the Lundahl LL1540? Or is there some components that I would need to remove from the board to take the input section out of the circuit?

http://mnats.net/1176-wiring.html

Mark

 

[casrec]

Hey all,
    I just finished my own 1176 rev F Using OEP's on the input and output with hairballs 3deck input attenuator. Works and sounds great. Ohh, and wiring series compared to parallel makes a huge difference in sound and I eventually ended up with 2:1 in series on the input and 1:2 Parallel on the output. Any who, the only problem that I am having and can not figure out is that the meter drifts from slightly under 0db to slightly over 0db in GR mode. It drifts back and forth and so on in a couple minute period. And it is not hairballs meter because it did the same thing when I built Mnat's version using a sifam. I also opted to use a TL071 in the Meter driver amp. Is C16 in the schematic vital? Mnat's version said it was optional as pin 8 is not connected on the TL071. I am curious to know if this might be used to stabilize the meter. I have know idea and would love some input on this matter. Also, the OEP doesn't call for a terminating resistor like the lundhals, would there be any adverse reaction to use this resistor if the trannie doesn't call for one. Thanks for all the help guys!

Brandon

P.S. I'll put pics up soon. Purple heart Laminated to aluminum and front panel express is amazing and the only company that would even attempt to mill this material. They also did an amazing job and I highly recommend them.       

 

[danjpiscina]

Hi Guys. I'm wiring mnats rev F with Hairball i/p and o/p transformers. is there an official wiring guide around here? lots of wires on the output one and it's kind of freaking me out! Don't want to get something wrong and fry the board! Thanks for listening.

DP.

 

[mnats]

Hi Guys. I'm wiring mnats rev F with Hairball i/p and o/p transformers. is there an official wiring guide around here? lots of wires on the output one and it's kind of freaking me out! Don't want to get something wrong and fry the board! Thanks for listening.

DP.

Hey Dan - I sent you the link of the Rev F thread so you could ask questions there - did you get it? This thread is for the G1176 which is very different visually so if you're looking for a drawing a G1176 one won't help you much...

 

[casrec]

  Don't know if anyone is reading this, but since i got no answer i soldered a 33pf cap directly to the legs of the TL071(pin 1 and 8 ) and haven't had any drift what so ever. Been about 30 minutes and the meter hasn't budged from zero. I would say that you need this cap.

Brandon


sorry, that wasn't supposed to be a smiley face

 

[gswan]

Pin 1 and 5 of the TL071 are the offset nulling pins. If you look at the TL071 circuit you can see that  they connect across the 1080 ohm emitter resitors in the current mirror.

 

[casrec]

Pin 1 and 5 of the TL071 are the offset nulling pins. If you look at the TL071 circuit you can see that  they connect across the 1080 ohm emitter resitors in the current mirror.

sorry, it put a smiley face in my post. It was supposed to say pin 1 and 8, which pin 8 is not connected. I was having drift of up to 1bd + and - and since i put the 33pf cap in place as in the schematic, across pins 1 and 8 there has been none.

 

[gswan]

Not sure what the NC pin is internally connected to. Sometimes nothing, sometimes the substrate. It could also be different between brands of op amp too.
I would not recommend connecting anything to this pin, you don't know what other effects you may be having on the op amp by connecting to it. It would be safer to simply add a small capacitor between pin 1 and GND to bypass the current mirror resistor (as an experiment). If this does the same thing then it's a more consistent approach.

 

[casrec]

Not sure what the NC pin is internally connected to. Sometimes nothing, sometimes the substrate. It could also be different between brands of op amp too.
I would not recommend connecting anything to this pin, you don't know what other effects you may be having on the op amp by connecting to it. It would be safer to simply add a small capacitor between pin 1 and GND to bypass the current mirror resistor (as an experiment). If this does the same thing then it's a more consistent approach.

 
The Rev K schematic shows C16 being connected to pins 1 and 8 of the TL071. It Did stop the drifting. Saying that I will give wiring it to the ground a go. Also I used A TI Chip. Thanks!

Brandon

 

[mac]

Hello All,

I recieved my box of goodies from Mike this week and have set about understanding the wiring for the output transformers (B11148's) for my dual build on Mnats Rev J boards. From my reading here and reviewing the Urei schematics I understand in the Urei 1176LN manual schematic for REV "F", four pairs are made from Red/Yellow, Brown/Orange, Green/Violet and Blue/Grey.

Mako's boards provide a number of options in terms of transformer choice, orientation and connectivity, but it was fairly straightforward to see that one option to make these trafos work, is to put the Red/Yellow pair into position (1) and the Brown/Orange pair into position (3).

My question (and I know you were thinking - does he have one?)....is concerning R84, the x & y pads and impacts upon metering. From how I understand these boards, and the original schematic, R84 is possibly not required when using the B11148, so theoretically I could take my Green/Violet and Blue/Gray pairs straight to pins 2 and 3 of my XLR - However, if I did this, doesnt this also impact upon my metering and switching?

Perhaps the best is to remove R84 and wire these to X and Y pads - and take the outputs from the standard pin positions Bal Output + 0 -.??

thanks,
Mac.

 

[onlymeeee]

Isn't it easier to put the secondaries from the transformer where the secondary goes on the PCB?
ie. opposite where you put the red/yellow and brn/orang.

Haven't got the schematic in front of me but if you went in (1) and (3) then put the secondaries somewhere between (6) to (10)

 

[mac]

Yes,
in essence this is my question, whilst the Rev "F" schematic shows the secondaries going straight to the output, for these boards do I need to return them?

Or is it just a case as you say of being "easier", in terms of hooking up. If i do wire the secondaries back to the board, should I remove R84?

Thanks,
Mac.

 

[adrian]

hello,
since last time i checked my 1176 with a generator and an oscilloscope, i used this website  to compare my results:
http://www.axtsystems.com/index.php?view=article&catid=34%3A1176ln&id=57%3A1176lnproblems&option=com_content&Itemid=62

i found some problem on transistor values:
i have to much gain on Q5 ( 1,6V instead of 0,5V )
and to much gain on Q8 and Q9 ( 5V in place of 2V )
but Q6 ans Q7 seemed to be ok,

i tried to replace Q5 but it doesn't change anything!
what else could i try ?

thanks!

 

[casrec]

Yes,
in essence this is my question, whilst the Rev "F" schematic shows the secondaries going straight to the output, for these boards do I need to return them?

Or is it just a case as you say of being "easier", in terms of hooking up. If i do wire the secondaries back to the board, should I remove R84?

Thanks,
Mac.

Hey Mac,
  I have asked this question many times with no clear results. The only answer that I got was that R84 is a terminating resistor that the output trannie may or may not need. I know that the B11148 doesn't call to be terminated. I removed it using the OEP trannie and instantly i could hear a difference. OEP's also do not call for this resistor either and removing it brought a lot more life to the high end. Hope this helped.

Brandon

 

[onlymeeee]

The only way to know for sure whether R84 is needed is to use a scope really.
Obviously as it's not used on the F rev (B11148), I'd try it like that first.
Of course you may like the sound of a transformer ringing but that is a different discussion.

I'd return the secondaries to the board for ease really.  ie. you can use a header for the - 0 +. You can try different value R84 or none at all. You've X and Y all connected.  If you go secondaries straight to the XLR you will not have these things, however you can still make it work. So up to you really.

 

[mac]

Hey thanks for the responses guys,

Mac.