All things G1176 - the new "repost" thread.

[adoucette]

ahh i understand, that makes more sense.. Good thing I checked! Thanks for the help both of you

(ps. changed my signature to something more fitting for this board haha)

 

[3nity]

Guys i'm using 2N5457 instead of BF245 here....but do i have to reverse it or turn it 180 degrees?

 

[maxheadroom]

i am using the 2n5457 also. you must turn him 180°. the middle pin is the same. the outer pins are swaped.

 

[3nity]

alright thats a step forward!
Thanks max.

 

[crisotop]

I just fired my very first mnats 1176 channel up for the first time and it's working! that's the good news, now the questions, because I couldn't find anything with a search on the board:

Mnats Meter board bypass, switches the gain reduction off and also the meter output, which makes it hard to calibrate the unit. Is there an easy way to use the mater board bypass position just to bypass the vu (like an original unit) and use a separate switch to turn of the gain reduction circuit?

EDIT: After (trying to) using my brain a litte I figured out it has to be the connection of pad 4 and 22 on the meter boar, that also turns off gain reduction? If I'd use another siwtch to dis/connect them both, I'd have the same GR bypass switch like the ccw attack knob on the older units right?

Many Thanks
Christoph

 

[mnats]

[quote author="crisotop"]Mnats Meter board bypass, switches the gain reduction off and also the meter output, which makes it hard to calibrate the unit. Is there an easy way to use the mater board bypass position just to bypass the vu (like an original unit) and use a separate switch to turn of the gain reduction circuit?[/quote]
That's Jakob's bypass I used on my boards :wink:

Though this Q Bias video is aimed at Rev D builders, the idea for switching off the gain reduction will work for the original G1176 type units as well:

http://www.mnats.net/1176_revision_d.html#videos

 

[lofi]

just finished the wires on my second 1176, fired her up and its clicking. best description is a very regular click with a second almost echo just after, main click is about 1 second apart (just under).

i had to leave the studio a few mins after firing her up so not had a chance to really check, but the scope showed the click on the -10 not the 30. its a dual unit, so i touched the scope to the wires and the click is only present on the -10 wire.

the other unit works fine and click free.

i found a pcb diagram with expected voltages on it a bit back but never bookmarked the page, could anybody here point me to some info on where i can start looking.

i must be able to d/load it though as i have no internet access in the studio.

all help very greatfully received

Iain

 

[crisotop]

Brilliant Videos Mako! I wired my unit now exactly as i wrote in the previous thread - the meter switch now disables only the vu in when in bypass mode (handy for super heavy compression, when the meter slamming to just one side), and I'm using a second switch to take out the compressors gain reduction circuit (Pad 4 + 22). One channel of my dual unit is happily compressing and already calibrated! But I might redo the wiring, it's a bit untidy :/ Does anyone have farnell order codes for those matrix pins Mako is using on his build?

Thanks!
Christoph

 

[gswan]

[quote author="lofi"]just finished the wires on my second 1176, fired her up and its clicking. best description is a very regular click with a second almost echo just after, main click is about 1 second apart (just under).

i had to leave the studio a few mins after firing her up so not had a chance to really check, but the scope showed the click on the -10 not the 30. its a dual unit, so i touched the scope to the wires and the click is only present on the -10 wire.

the other unit works fine and click free.

i found a pcb diagram with expected voltages on it a bit back but never bookmarked the page, could anybody here point me to some info on where i can start looking.

i must be able to d/load it though as i have no internet access in the studio.

all help very greatfully received

Iain[/quote]

Do you have separate PSU's or one common PSU powering both units?
What does the 'click' look like on the scope?

 

[lofi]

single PSU from Mnats, think its the culprit :sad: although only in as far as its common to the pair. the click is just a line above and below center for as long as it takes to say click.

i had also thought i would stack the boards to save space, nope thats not happening, too much interference :sad:

now for the good news, i was thinking about making a pre/comp box, so i recon a fetbloak front end with di into the spare 1176 (solid front OEP output) picking up the compression, nice little project me thinks.

I am really greatful for all the help i have received here


:thumb: :thumb:

Iain

 

[gswan]

If the click is in both units then it's probably being coupled from the PSU. However, if you can remove the second unit and it stops then it's probably coming from the second unit.

If it's not in both units then it is coming from the second unit. If it's a clear spike on the -10V rail then you will need to check everything connected to the -10V rail on the second unit.

 

[lofi]

its in both, so i went for the PSU ... any idea why (newb question that, and i'm proud of it :grin: , seriously though i am interested in why or what is causing this for future reference, any ideas on how to investigate?)

i'm going to rip the innards apart on the second unit and use it to study till i am ready to build the strip

Iain

 

[gswan]

[quote author="lofi"]its in both, so i went for the PSU ... any idea why (newb question that, and i'm proud of it :grin: , seriously though i am interested in why or what is causing this for future reference, any ideas on how to investigate?)[/quote]

It may only be coupled through the PSU and be caused by the second unit. If you remove the seond unit and it stops, it's likely that the second unit is the cause.

You should also know what kind of pulse/noise you are dealing with by examining it closely on the scope. This will give clues as to what is happening. Then you can examine and isolate the causes on the second module until you pinpoint it.

 

[lofi]

its only present when both are conected, if either is removed the sound dissapears, but its common to both units when they are fired up.

I will be able to research fully over the next few days, about time i learnt how to use a bloody scope anyway :grin: :grin:

Iain

 

[gswan]

[quote author="lofi"]its only present when both are conected, if either is removed the sound dissapears, but its common to both units when they are fired up.[/quote]

Do you have any other loads hanging off the -10V rail? Is the regulator for the -10V rail (U2 - LM337) getting warm? Mako's PSU is a pretty standard, well tested design so it may have to do with the way it's loaded.

 

[lofi]

nope, just the boards, and it fine to touch :?:

im in the studio tomoz night so will go at it and see what i can come up with.

i know its down to me somewhere, but the answer might help somebody else. i thought it might be the C3 C4 problem mentioned around page 100, but mines a constant volume regardless of pots position.

 

[3nity]

i'm looking at the 1176 with scope at Q12 Base with signal at the output pot.
and instead of having something like this:

Is there anything wrong ??

 

[gswan]

[quote author="3nity"]i'm looking at the 1176 with scope at Q12 Base with signal at the output pot.

Is there anything wrong ??[/quote]
Not if you like distortion :wink:
Check the signal at the top of the output pot (ie the output of the pre-amp section). Maybe you are driving it too hard. What is the signal amplitude you are getting there?

 

[JW]

Quick question here.

I'm using the Mnats little PSU. At the bottom of the page where Mnats shows where the psu is connected to the main board, are the parts that are missing on the main board all supposed to be left out? In other words, make my board look like the pic? I can see that I don't need the filter caps, but Mnats never says (or I just haven't found it) specifically that all the parts that are missing in the pic should definitely be left out. I don't understand the p.s. enough yet to be able to tell on my own.

Pic here: http://www.geocities.com/m_natsume/psu.html

 

[gswan]

Leave the PSU parts off the main board, since you are supplying your own +30V, GND, -10V rails. These rails need to connect to their required points on the main board from the socket, hence the links to bypass the regulator etc.

So you will leave out the regulator and the zener, the regulator bias resistors and the additional resistors R85, R86 and the 4 diodes.

You will then need to insert links to connect the rails from the connector to the supply points on the module.

There's no harm in leaving the filter caps in, especially if you have a long cable run from your PSU board to the compressor module.