All things G1176 - the new "repost" thread.

[gswan]

It's not quite that simple.
Your meter lamps probably draw more power than the actual circuit and you are probably using a toroid transformer which has a relatively high inrush current (switch on).
As a rough guide to fusing, if you are using a 30VA transformer you are probably drawing about 15VA total. At 220V, this works out at about 70mA. You won't get a fuse this small and we need to allow for the inrush surrent. So I'd suggest using a slow-blow fuse (to accommodate the short switch on peak) at about 0.5A rating.

 

[lofi]

thanks Sir, now i just have to figure out how you got to that math, is it 15Va/220V=0.07A roughly?

 

[hugoderwolf]

I am building a Stereo 1176 at the moment and it's nearly finished. I fired it up today and Channel 1 works really fine (and sounds great btw, never had an 1176, neither hard or soft). But Channel 2 has a weird Problem. The Input pot doesn't do anything.

I've got Output full clockwise and input full ccw. Send in -6dB and out comes -21dB. When I turn the input pot nothing happens, output level stays same. Meter switch is on bypass, but it doesn't matter. The only control that really does anything in this state is the output pot.

I double-, triple-, quad-checked the pot's wiring and it's alright. The pot itself measured ok too. And it's the right value. When i pull off the Connector to point *1 (Transformer Input) on the PCB it gets quiet. When I disconnect the pot's shield on Point 3, level stay the same, still no effect when turning the pot.
When I disconnect the wiper and just connect the shield, signal comes through, too. But a bit lower at about -31dB.

Any ideas on how to find the problem?

 

[gswan]

If you really think the input pot is the problem then bypass it completely (ie short the top and wiper together). Now see if you get any signal through. If not then you have a different problem, probably not related to the pot (check your input connector wiring, you might have hot and gnd swapped on it).

 

[3nity]

Hey guys i'll be turning my 1176 for the first time in a half an hour...any thing i just might take into consideration?
Thanks.

 

[gswan]

Power it up in a non-destructive way.
- Check the power supplies before connecting to other modules (if you constructed it with on-board PSU's then you have already done this, right?).
- If you built 2 channels, power up one channel at a time.
- Double check that all transistors are in the correct way around.

 

[3nity]

All transistors are in the good way.
And yes the psu is in the same board.

 

[kenrinc]

Just thought about something else. For you guys doing dual units, how are you dealing with the wiring from the power supply? I've got mnats supply and trying to figure out how to daisy chain everything to those 3 connectors at the front is a pain in the a**. Does it make sense to make a custom wire header? So far I need power for two 1176s plus wires for power to the lamps on the meters (apparently the pads marked vu lamp don't work on mnats board, at least mine don't). You just stuff them all into that little pcb header?

ken

 

[gswan]

What do you plan to power your VU lamps from? Are they 6V or 12V lamps? The PSU puts out -10V and +30V for the audio circuitry. I guess you could put two 12V lamps in series and power them from one of the 25VAC transformer windings.

For the compressor module supply wiring it's just a matter of running the cables to the power supply and twisting the pairs together before inserting into the terminal block. You don't need to use really thick wire here, the modules are not drawing very much power.

 

[kenrinc]

Ok you just reconfirmed what I was going to do (twisting and connecting to the terminal blocks) just looking for confirmation there.

I replaced my lamps with LED's powered from the 30vdc. I just have a chain that includes the 2 vu lamps as well as the power lamp. Works and looks great.

Ken-

 

[3nity]

Alright guys i just powered mine few minutes ago and nothing smoked.
but i notice R87 is getting very hot.
Although i read some post saying that is normal i just wanna make sure it cant blown!

Gonna pass some audio trough it in a few minutes!

 

[gswan]

Why don't you test and calibrate it first?
It's completely senseless to 'pass audio through' an uncalibrated, untested unit.

 

[3nity]

You're right!
I'll do it like that!
bur before i'll eat something! its dinner time! :twisted:

 

[MartyMart]

[quote author="kenrinc"]MM,

Are you actually DI'ing directly into the input of your 1176? No pre beforehand?

Ken[/quote]

Yup, Behringer Di for guitar with speaker sim circuit running off a battery.
I think it's a GI-100.
MM.

 

[lofi]

i wanted to see my one working tonight, so i took a di off the bass amp into my pres, into the DAW then back out though the comp and back in, recorded both channels

kept it as hot as i could on both, just below clipping, and was very happy with the results, i havent got a VU meter at the moment so it allowed me to visually see the thing working.

ker nice!!!

going to run a proper trial in a day or two.

Iain

 

[3nity]

Hey guys do you know if the OEP needs a Resistor load?
i'm injecting it with a 1K sine wave and on the primaries i see it but not on the secondaries?? any clue?

 

[gswan]

You may have a short circuit on the secondary, your input may not be connected to the primary as you think, you are not measuring the secondary windings or one of your windings may be open circuit (or not joining two primary or secondary windings to form a different turns ratio).

 

[Dr nEon]

Hey guys!

I've just pulled my g1176 out of the rack to check calibration , and while doing that I've noticed that some of my ratios aren't correct...20:1 is spot on , but 4:1 is about 6:1 , and the other two positions are also pretty high.

I've searched for a coupla hours , but can't seem to find anything on calibrating ratio in the 1176 ..(this topic is well covered for gssls)

Any pointers,or links to known threads on this would be appreciated..

cheers

nEon.

 

[gswan]

It depends on how you measured them. The knee for the compressor is quite soft so you need to push it hard to measure the compression ratio in a fairly linear section of the curve.

I have found the compression ratios can vary quite a bit between identical units (welcome to the world of vintage analogue equipment). However you can adjust your compression ratios to be closer to the dial values by manually selecting the resistor values on the ratio switch. It's a long and tedious process. Good luck.

 

[3nity]

To Gswan.
I took out the transformer and tested outside the circuit.
It works just fine.

I tried to do the Calibration but my meter wont move more than half a 1db.