All things G1176 - the new "repost" thread.

[audiophreak]

Hi All,
        Well, it looks like I stopped this thread in its tracks ... again  :     

    Just wanted to send a great big  THANK YOU to mnats, gswan, Echo North, gemini86, PRR, Jakob, axtsystems , and all who posted and contributed and to this wonderful forum. such a wealth of knowledge .

  I have finished my mnats Dual 1176 - finally - and could not be happier , after all was said and done , my main problem was I had installed c16 , that's why I couldn't get the meter to drop during the calibration , and also I used LOG pots on IN and OUT  and they get very touchy 3/4s on CW rotation.

  I ended up putting a master power dwitch on the back to power the PSU , wired the 0v directly to the Rev.J boards and sent the +30v and -10v to the push button ON/OFF switched then to the Rev.J boards .

Here is a link to some pix -  I have learned so much ... but have so much more to learn.


https://picasaweb.google.com/audiophreeek/DualMnats1176LN?authuser=0&feat=directlink

Thanks again,
                    Chip

 

[simonsez]

Hi guys,

When we do "Q" bias adjustment, some says that the trimmer start from CW position, some says at CCW posistion,  but which one is right one? When the wiper connect to ground or the other side?

Thanks...

 

[mnats]

Hi guys,

When we do "Q" bias adjustment, some says that the trimmer start from CW position, some says at CCW posistion,  but which one is right one? When the wiper connect to ground or the other side?

Thanks...

CW or CCW? Depends on the construction of the trimmer, orientation etc.
Start at the position that produces the least gain reduction. Turn until the output drops  1 dB. Make sense?

 

[simonsez]

Hi guys,

When we do "Q" bias adjustment, some says that the trimmer start from CW position, some says at CCW posistion,  but which one is right one? When the wiper connect to ground or the other side?

Thanks...

CW or CCW? Depends on the construction of the trimmer, orientation etc.
Start at the position that produces the least gain reduction. Turn until the output drops  1 dB. Make sense?

Yes, mine that would be fully turn CW, then turn back CCW untill the meter drops 1dB, just to make sure...

I have weird problem with ratio push buttons, i did check many times that the wiring is right (i hope), but the ratio buttons seems respond reverse/backward. At ratio 4 that the largest compression occur, at ratio 20 that the smallest compression, but the AC voltage came into sidechain amp seems right, the higher ratio, the higher AC voltage...

All DC voltage seems ok..( i hope  )

Any clue?

Many thanks,

Simon

 

[gyraf]

you should really try reading some of this thread before asking new questions. threshold changes with ratio.

Jakob E.

 

[simonsez]

you should really try reading some of this thread before asking new questions. threshold changes with ratio.

Jakob E.

Jakob, you just save my days. I spend the hole 2 days trying to figure out whats wrong.... :-[ :-[

So, it's normal.....thanks for the keywords...

http://www.groupdiy.com/index.php?topic=46112.0
http://www.gearslutz.com/board/so-much-gear-so-little-time/64308-my-1176-f-d.html
http://www.gearslutz.com/board/so-much-gear-so-little-time/538492-1176-ratio-problem.html


Simon

 

[JW]

I'm curious if anybody has tried Carnhill transformers with the G1176? Looks like the CA-18-VTB2290 could be wired 2:1 or 1:2 of course by reversing it.

Any comments?

I currently have the recommended OEP's on the in and the outs (w/ a switch to change the input to electronically balanced which I always prefer over the OEP input)

 

[drumminkiger]

Greetings all,

I have a quick question about lamp wiring on a Dual 1176 with hairball LED meters and a pilot light jewel in the middle of the unit. If I take the voltage from the secondary to wire up the lights, I will need a resistor to cut the voltage. Now, If i wire this in parallel, will I need to figure the voltage for about 6 volts and then .270 MA or should I run it in series and figure for 18 volts (6 for each light) and .270 MA. I'm using the equation off of mnats site to figure this, so it looks something like:

30.4-18= 12.4v or 30.4-6= 24.4v

12.4/.270= 45.92 Ohm's or 24.4/.270= 90.37 Ohm's

I would round these up to the nearest standard 5w value obviously. so either a 50 or 100 Ohm resistor. I initially tried a 220 ohm in parallel going off of the jewel lugs and it wont light up the LED's in the meters because the voltage is too low I imagine, but it does light up the incandescent jewel a little bit. 

- Kiger

 

[mac]

ok ...
    have now calibrated both channels , I think I will eventually change out the in and out  pots to LIN , with LOG they get very touchy . 

  need some advice / suggestions
                                                I am using Haiball push button meter switches , and planed on using them for power too , however now that I have everything in the case , not sure I want mains power going to and from two places on the front panel - sooooo , was thinking about using a main power switch on the rear panel to  power mnats PSU board, permanently  wiring the 0v to the Rev.J boards and switching the +30v / -10v with the Hairball switches from the PSU board to the REv.J boards.
 
  Is this advisable ??  any problems with doing it this way ??

  Thanks,
              Chip

Hey Chip.
Nothing wrong with running mains to the front panel, (thats how thw original is wired) and switching mains at the rear as well if u wanted to.
Just saw your last post, and glad to see that switching the DC on the front panel works for you.

One thing to consider however, is that you may get in the habit of simply switching "off" at the front panel, and not the mains switch at the rear.

Whilst this will power down your main boards, and front panel VU etc, your PSU remains powered up.
Possibility of early PSU cap failure, etc there. I am careful about any equipment left running in my studio, in case of fire etc.....

Good job on your successful build!

Mac

 

[audiophreak]

Hi Mac  ,
  Just saw this ,  I dont have a problem with running mains power to the front panel but as you can see from my pix that I have a bit of a  rats nest of wires between the main PCBs , push button PCBs , Pots and ratio switchs - I didnt want to run mains power through all the signal cabling - ( I should have thought this part  through better )  ;D

  .. and yes , I  definitely need to remember to turn off master mains switch - dont want to leave the PSU idle.

  Thanks Mac 

 

 

[mac]

Hey chip,
I have done way worse spaghetti bowls than yours .... Just had another look at your pics and I actually think for a dual 76 on J boards ......it is actually quite neat!!

Hey ,... I meant to say last time too....Really beautiful front panel Mate... Well done.!!!

If you do decide to run mains to the front, just use nice fat cable and twist it up....cross any audio at 90deg and you should be fine. I strip down twin and earth cable (mains house cable) for my psu cabling and haven't had any issues ..... Most of your noise will come from the trafo ....

Mac

 

[audiophreak]

Hey chip,
I have done way worse spaghetti bowls than yours .... Just had another look at your pics and I actually think for a dual 76 on J boards ......it is actually quite neat!!

Hey ,... I meant to say last time too....Really beautiful front panel Mate... Well done.!!!

If you do decide to run mains to the front, just use nice fat cable and twist it up....cross any audio at 90deg and you should be fine. I strip down twin and earth cable (mains house cable) for my psu cabling and haven't had any issues ..... Most of your noise will come from the trafo ....

Mac

    Thanks Mac ,
                          nice trick with stripping the house mains cable , I think I might try that !!  I did the front panel in Illustrator and had Chae at Prodigy Engineering laser engrave it.

  Thanks so much 
                                  Chip

     

 

[dryman]

I have some small problems, with my dual 1176(mnats Rev J) build. One of the is, that the input-transformer (LL1540) is not working on both of the boards. I cannot find a suitable schematic for the Rev J. All of the schematics, i found, doesn't show the input transformer. Is there any schematic for the Rev J out there?

 

[s2udio]

Yup ...all you will need to know

http://www.axtsystems.com/index.php?option=com_content&view=article&id=76:1176project&catid=45rojdownloads&Itemid=78

As Gyraf quoted....search

Took less than 10 parsecs of search time

 

[mokkinger]

Hi guys,

I noticed last week that the right chn. of my dual 1176 (rev J mnats with lundahls, have build it 2-3 years ago) only passes very little and somewhat distorted audio anymore, in compressed- as well as in bypass-mode, and the meter doesnt go up to 0db when powered, instead moving around or just stays at -20; however one day it came back and worked like before, but then again the meter began moving weird (without any input signal) and now the channel is dead again; the left channel works like allways;

so next, besides checking for obvious loose cables and that, what should I suspect first and where on the channel should I search for the problem? some months ago I noticed some clicks and pops on this channel while in use, but then again all was fine so I didnt bother by that time...

thanks for any hints,
mark



 

 

[gyraf]

check your +30/-10V power supplies on the faulty board?

 

[RyanB]

Hey Guys,

it's me again 

Long long time ago I have built the 1176LN rev#F from Gyraf without the input
transformer and it never works right.

Now I have check it again with the troubleshooting from axtsystems.

I measured all the Voltages of each transitor and it looks ok. Some values are a little bit lower.
For example:
Q        B        C          E
2        0,97    1,7      0,43
3        1,7      10,05  1,08
4        10,05  29,43  9,45

Then I have check the input amp with 1kHz 1Vpp sine wave at the input.
At the output I measure 0,78Vpp, at the input pot 1Vpp and the output pot 0,46Vpp.
At the base of Q2 22mVpp, Q3 0Vpp (or something very low) and at Q3 500mVpp.

I have checked several times the parts, looks all good.

Please help me !?!?

 

[RyanB]

Hey Guys,

after reading some posts here I checked all the resistors again and I found a wrong one. R11 was a 560Ohm and not a 560kOhm.

After I changed it to the right one I get the following situation:

Input:            1Vpp
Output:          3,6Vpp
Input pot:      1Vpp
Output pot:    2,2Vpp
Q2 Base:        15mVpp
Q3 Base:        15mVpp
Q4 Base:        2Vpp
Q5 Base:        2Vpp
Q6 Base:        20mVpp
Q7 Base:        20mVpp
Q8 Base:        7Vpp
Q9 Base:        7Vpp

The DC voltages of the transitors now a little bit higher.
For example:
Q        B      C        E
2        1,02  1,74  0,51
8        14,1  29,4  13,5

I also check the voltage of IC2 (5532)
Pin 1: 14,7V
Pin 2: 14,75V
Pin 3: 14,7V
Pin 4: 0V
Pin 5: 14,7V
Pin 6: 14,7V
Pin 7: 14,7V
Pin 8: 29,5V

What can I do now? Please help me!!

 

[skal1]

ok lads,

i do not know if this is a problem , or i am reading the +4 scale wrong.


procedure.

i inject a 0 dbu signal into Rev j 1176 , on the out i have a farnell millivolt meter that shows me the out level in db's, which corresponds to the injected signal .

so now i look across to the 1176 meter in the plus +4 scale and i see -7 on the meter is this correct or am i missing something.

cheers

skal

 

[RyanB]

No one can help me ?  :'(