All things G1176 - the new "repost" thread.

[gswan]

No, definitely not. That's what will give you a scratchy sound.

There's a blocking cap into the top of the pot and one from the wiper. If these are OK then you must have DC coming from the ratio board back into the top of the pot.

 

[flintan]

Thanks! Exactly my thought too but i wasn't really sure...

DC is sill there when wiper is turned to ground so it has to be from either the pre-amp section (bad C9) or ratio section.

Edit: I forgot to say, the voltage doesn't change when changeing ratio, neither with nuke in/out or when it's in bypass.. This doesn't make sense to me.

 

[guitarguy12387]

Alright guys, i have been lurking for a while and am now working on mnats rev j. version of this project.

Please be patient with me! I'm a noob to DIY audio stuff.

Alright, i have come up with some things i want to make sure of:

1) How do i know which way the rotary switches (S1, S2) go in the board? I'm using the lorlin switches. Hehe sorry... told you i was a noob.

2) I plan on using Lundahl input transformer in a 2:1 ratio. Are R* and R*1 still 12k in this application?

3) I think i read somewhere that all the components with an * are required if using an input transformer. That is, C*, C*1, C*2, C*3, R*, R*1. I just wanted to make sure that's correct.

4) What's the purpose of C16? Is it best to include it or not?

Thanks in advance for your time and patience.

 

[flintan]

You can put the Lorlin's any way, they are symmetric around all poles. C16 is not used IIRC.

Have a look at Mnats 1176 page: http://www.geocities.com/m_natsume/1176.html

 

[guitarguy12387]

Hey thanks for the reply. Yes i have been all over mnats page. The only thing i could find about the components with the asteriks is from the FAQ page:

"The components marked * on the board are optional components not included in the original unit or schematic. "

But i can't find when i should or should not use them.

And for R* and R*1, on the FAQ page, it says (if using the lundahl) use 10k and on the boards and other places it says use 12k. Can't figure out which to use.

Thanks again!

 

[gswan]

Use the capacitors. They provide extra decoupling for the PSU that will help to keep noise down.

 

[guitarguy12387]

Thanks again.

Alright, i'm back with another noob question that i just cannot find an answer to:

Why is the ratio board six position when there are only four ratio options?

 

[kenrinc]

For the R*1, I wouldn't get worked up about it. Start with 10k and if it doesn't sound right or you get better info, change it.

The revJ uses a 5 position 2 deck switch not a 6 position. The positions are 4:1, 8:1, 12:1, 20:1 and SLAM (all buttons). Part# 105-SR2921F-25S at Mouser.

Ken-

 

[guitarguy12387]

Hey Ken,

Thanks for the reply. I figured the fifth position was for slam mode. However, according to mnats BOM, its a six position...

 

[mnats]

[quote author="guitarguy12387"]However, according to mnats BOM, its a six position...[/quote]
I should probably just get over it, but I really dislike like being misquoted. The switch that does the "nuke" or "slam" function is not on my BOM. That switch listed on the BOM is for the normal four position ratio selection.
[quote author="guitarguy12387"]Why is the ratio board six position when there are only four ratio options?[/quote]
Spend a few minutes investigating the switch, take a look at the data sheet or do a proper search. Hopefully you're not just trying to make a "cheap 1176" but are doing it to learn something...

 

[guitarguy12387]

I should probably just get over it, but I really dislike like being misquoted. The switch that does the "nuke" or "slam" function is not on my BOM. That switch listed on the BOM is for the normal four position ratio selection.

I am a little confused. First off, i'll just clear up, i'm not planning on using the ratio switch for nuke mode. Where i am confused is...

LORLIN OR ALPHA 2 POLE 6 POSITION SWITCH S1

Copied right from your BOM. I am not trying to be disrespectful... i just don't understand what you're trying to say. Maybe i am misunderstanding that that switch can somehow be used as a 4 position switch or something? I dunno... i'm all confused.

Spend a few minutes investigating the switch, take a look at the data sheet or do a proper search. Hopefully you're not just trying to make a "cheap 1176" but are doing it to learn something...

I did spend some time looking at the datasheets for a few of the switches, but i cannot figure out what i'm missing :sad:

Sorry if i'm frustratingly ignorant hah. Thanks again.

 

[Gwaggin390]

ultimately, you wire only 4 of the positions so it suits your needs and on many rotary switches, you can actually adjust the number of stops, usually with a little pin(often supplied).

so you buy a rotary with MORE stops than you need, and then adjust the stops to suit your needs.

in a worst case scenario, you have unused stops.
the world usually won't end because of this, but it's been known to happen.

 

[guitarguy12387]

aha! Ok that makes sense. I just wanted to make sure i wasn't missing something important. Thank you very much for the help!

 

[kenrinc]

guitarguy, I understand what your saying now. I think I looked over the BOM multiple times when sourcing parts so when it came time to get the ratio switch I already knew what it was because mnats posted a page about it here: http://www.geocities.com/m_natsume/1176_slam_mode_rotary.html

But that only helps people building the unit with the SLAM feature (although I call mine NUKE ). Since I was building a dual 1176 similar to what mnats had done, I already knew what switch I needed so I ignored the 6 pos switch on the BOM. As someone mentioned, I was told you could adjust a pin in the frame of the switch to change how many pos it had. Never used one though.

$.02

Ken-

 

[guitarguy12387]

Ok ok. I see what you mean. Yeah... i wasn't planning on using nuke mode on the rotary switch anyway so i just wondered.

And i checked under the nut/lock washer and sure enough, there's another washer type thing with a little tab in it that i can adjust the number of positions. Thanks for the help

 

[Dr nEon]

Hi everyone!

Could anyone please confirm if the g1176 's output -ve (cold) on xlr pin 3 should be grounded to pin 1 , when running into an unbalanced line.

I'm just checking my cabling to an unbalanced patchbay , and although my G1176 seems to be fine, I've been reading about transformer outs , and the need to ground one side..

The thing is , at the moment , I have pin 2 to tip and pin 3 to shield , with n/c at pin 1 .

Is this wrong?...or is it simply grounding at the other end?

cheers

nEon

 

[gswan]

It's a transformer output, so the output appears across the transformer secondary side only.

To connect this to an unbalanced input, which is expecting a signal referenced to its GND, you will need to connect the cold side of the output to the GND and the hot side to the unbalanced signal input.

 

[Dr nEon]

unbalanced input, which is expecting a signal referenced to its GND, you will need to connect the cold side of the output to the GND and the hot side to the unbalanced signal input.

That sounds like what I already have, gswan..the ground ref is the unbalanced input.

I just queried it because I have read articles which seem to suggest ALSO grounding the cold side at the BALANCED O/P end..i.e at xlr pin 1.

I've tried testing this by linking xlr pin 3 to 1 with a croc clip , just to see , and there is a subtle difference in the sound..very slightly more open/airy.
The fact that I can hear a difference makes me worry that there is a right&wrong way to do this..

There's a vast array of stuff written about interconnecting bal /unbal on the net , and a lot of conflicting ideas, for something that I used to think was pretty straightforward!

thanks

nEon

 

[gswan]

Connecting the GND between the pieces of equipment is OK unless you introduce grounding loops.

A passive DI box is a transformer which is used to provide galvanic isolation between the grounds. It should make no difference to the sound though. Unless you have to, I'd leave the GND off, since it does not carry the signal from the 1176 unit (it is a true balance output from a transformer).

As an aside, if it was a transformerless balanced output you probably would not want to short one of your driver outputs to GND, so the connection mechanism is different. You'd need GND and the hot side only in this case (since the signal is referenced to GND in this type of output).

 

[Dr nEon]

ok thanks gswan!

I guess i'll stick with things as they are , then ...with the xlr GND pin disconnected..

Many thanks

nEon.