All things G1176 - the new "repost" thread.

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Rob Flinn

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Can anyone point me to the wiring/build info for the rotary switch boards that have the R Opt1 Thresh pot on them ?  I've looked on mants site and here, but can't seem to find anything.
 

mnats

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Rob Flinn said:
Can anyone point me to the wiring/build info for the rotary switch boards that have the R Opt1 Thresh pot on them ?  I've looked on mants site and here, but can't seem to find anything.

I dug out an old board and posted a description here.
 
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Hi guys! Let me know please. If I'll connect two standard G1176 PCB's to one power transformer...is will be ok? And .. of its possible, how minimum power need for thit trans? Thanks!
 

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Whoops

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kurganyuriy1987 said:
Hi guys! Let me know please. If I'll connect two standard G1176 PCB's to one power transformer...is will be ok? And .. of its possible, how minimum power need for thit trans? Thanks!

It will be fine, you just need to meet the power requirements for 2 pcb's

My guess is that a 1Amp transformer would be enough for 2 units, but thats just a guess Im not sure
 

smadge

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Hi guys, I'm sorry if this is a very dumb question but can you offer me some help with my ratio rotary switch issue. For some reason my 20:1 sounds like 4:1 and vice versa. When I took a frequency/volume response into my DAW it confirms I seem to have something wired the wrong way round. But for the life of me I can't seem to work out where I've done this on the rotary switch board or the main board.  Have I wired them in reverse hence turing up the ratio is actually turing it down?

Ive got a Rev F/G board with a rotary switch for the compression ratio.

Again I'm sorry this is such a silly question but I'm stumped.

Thanks
smadge
 

gyraf

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Smadge,

Are you sure that you are not fooled by the change in threshold happening when changing ratio?

More compression at lower ratios is normal functioning at some input level ranges, because threshold is automatically reduced at low ratios...

Jakob E.
 

smadge

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Mmmm, thats a good point. Perhaps I hadn't thought of that.

How would I be able to determine whether my ratio switch is accidentally reversed?  Then I'd be able to determine if the issue is purely perception with threshold adjustment.

I accept your point Gyraf about more compensation happening at different input. But how can I be sure?

Thanks so much for your help
 

gyraf

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Measure ratio (d(in)/d(out)) difference only between e.g. 4dB and 10dB GR, that way you are out of threshold effects

Set to low ratio, set to compress e.g. 4dB, measure output, see how many dB more input level it takes to get output e.g. 6dB louder than was. Then try same for high ratio

Jakob E.
 

Spencerleehorton

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I've just done a sort of rev D mod to one of my stereo g1176.
Used the t-pad and used input and output txf, put the 270R resistor in after txf on input and replace C9 47uf for 1uf.
Have worked out how to change a few bits on the line amp so it gets to full Rev D but haven't done it yet.
Already both channels are sounding much better.
Going to take out the bc107 and replace for 2n5088.
Also planning on changing the output txf for the 5002.
Have had months and months of hassle with the Rev A so finally getting that where I want it, distorts like a charm, want to get these ones LN happy!
 

Spencerleehorton

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here my little mod if anyones interested, feel free to tell me ive done it completely wrong!!

This is what i'm suggesting:

bypass input IC and use txf:
put 270R on pin 2 to 3 on input

Pre-amp identical apart from
C9 change to 1uf

signal line amp
C10 – 1.0uf replace for C8 – 0.15uf
remove:
C11, R28
R30 change to 2.7M
R29 change to 2.7M
Link R29
cut track on 30v and put in R34 8.2K
Remove – Q8, R37, R35, R36, Q6, Q9, C15, R33, C13, C27, C14, R41, R40
C12 change fior 1uf
R32 change for 1.5K
R34 change for 27K
R39 change to 1N914
R38 change to 150K
Disconnect Q8 collector from 30v

control amp identical

and leave Meter driver amp
 

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Ubermusli

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I hope I'm asking in the right place, or that someone might point me in the right direction.

Is there anyone that has a schematic file for the 1176 Rev A (Old version)?
I'm modifying it with a feed forward option for my Bachelor's degree and can't even find a 2n3707 transistor for Eagle anywhere! Please, help!

Thanks!
 

Whoops

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Ubermusli said:
I hope I'm asking in the right place, or that someone might point me in the right direction.

Is there anyone that has a schematic file for the 1176 Rev A (Old version)?

You need to do to the proper thread for that project:

https://groupdiy.com/index.php?topic=29981.0
 

Chrome Heart

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I have an older moats rev j board, and for some reason when I put the meter selector in GR mode, it sends 7.5 volts to the VU meter. Any ideas?
 

Zebra_PD

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mihailojocic said:
It would be very cool to have "transformer-less/transformer" input switch on the front of the unit, like two options. In my head that sounds like grate idea! :) Components for  electronically balanced input isn't to expensive so I will keep them on the board if they don't interfere with transformer input.

Hi did you end up putting a input switch to your build? Did you get an answer if its possible to do so without having to add second/modified input amp?

Otherwise perhaps someonr else can help me with this question.

If input level is controlled by a transformer then the pot (or attenuator) is prior in the electronic chain to in the input transformer right? (if I look at the original UREI rev F for example).  But in the  UREI rev G/H the pot is AFTER the OPAs (IC2-A, IC2-B) ?

So in the transformer version the pot increases the voltage going from the input to the transformer input amp  and in the OPA version the pot decreases the voltage going from the input stage to the signal preamp stage? Or have a misunderstood the whole design difference now? Or is the first two ICs in the chain of the OPA version just to even the level of input voltage and not to directly effect the voltage of it? :)

If I by chance is correct would it then be possible to use a dual gang 10k pot, one gang to increase and the other one to decrease, to control the gain for the different input amps and then have a switch to change from OPA to Transformer based input?
 

momomo00

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Jun 21, 2018
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Hi guys im posting because my G1176 has an ungodly amount of hum.  :'(

Im mostly suspecting a ground loop somewhere because the hum seems to be all around the circuit. With the output turned all the way down the hum is still there, but when turned up a fraction it fades out and then comes back as its turned up more. When tracing from the input the hum starts off small and then when it hits Q3 it gets amplified to a huge hum. On the meter the GR position seems to work but the other positions are pushed to max, because of the hum. I made the recommended board cuts to try to stop the ground loop on the board but that didnt seem to help. The PSU plug ground is connected to the chassis, the transformers secondary is connected to the chassis, and the input XLR pin one is connected to the chassis. I noticed another guys had a similar issue but Im not sure if there was a solution found. Any help would be much appreciated. 

 

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