All things G1176 - the new "repost" thread.

[timpanic]

Okay, I will do that, but isn´t it strange that it works normal with the 20:1 ratio? Also the In and Output gain works, so I expect the voltage should be okay, at least when I switch the ratio to 20:1. It seems the error makes the threshold/GR needle to go down a lot.
What makes it really sick, is that I have to wait for one hour every time I want to work on it

 

[sylvainmoreau]

Hi,

i'm wiring my dual 1176 and the Mnats says about pad "4" :
But it may be beneficial to use shielded wire here, since that is what is used after the switch.
how do you use a shilded wire here ? you sold the inner cable on both sides to pads "4" and let the shield unsolded ? or you need to put it to the ground ? (does this make sense ?)
i don't know can you help me ?

best

 

[Spencerleehorton]

hi all,

have tried the Calibrate/setup procedure and cant get VU mode meter anywhere? so its definitely nothing i'm doing wrong in the setup.
both channels will calibrate in GR mode but nothing in VU mode?
Ive tried some other VU meters and exactly the same happens?
anyone got any ideas?

regards

Spence.

 

[gyraf]

Spence - have you verified that you actually have real vu-meters? Same error MANY times earlier in this thread....

Jakob E.

 

[Spencerleehorton]

Hi,

These are the meters I've got

http://www.ebay.co.uk/itm/121120434491?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Pretty sure they are ok?

Regards

Spence.

 

[gyraf]

These are the meters I've got
http://www.ebay.co.uk/itm/121120434491?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
Pretty sure they are ok?

I don't think they are - see the several similar problems previously solved: If it does not react correctly to AC audio, it's not a VU-meter. Ad shows only DC parameters. You will probably have to incorporate a diode bridge, either schottky or germanium low-drop types.

Jakob E.

 

[Spencerleehorton]

hi,

sorry yes i forgot to mention that i use a diode bridge, good call Jakob.
Just to update i have everything sort of working now, just have to change a few transistors as its all a bit too distorted.
Im starting to have fun with this oscilloscope now, tracing the signal through this wonderful beast!!!

regards

Spence.

 

[Spencerleehorton]

Hi all,

Is there documentation for all voltages of transistors? Not all are covered in the schematic and I'm getting a little confused in the line amp section where I seem to be having all my problems.
Q6  and Q7 collector voltage ? Is it the two voltages added together?
Q8 and Q9 seem to have very high voltage on emitter 27v on Q8 and 16v on Q9.
Q1 and Q10 voltages?
Q14 emitter voltage?

All other voltages seem within range, just got some weird stuff going in around these transistors!
Any advice is welcome on this.

I also have one sticky meter, have changed it for another one and it still gets stuck?
Any ideas? This seems to be an electronic issue rather than something going on with the meter?
Could it be the diode bridge?

Regards

Spence.

 

[Greg S.]

I Just update my 76ers,
here a pic

Have a nice Weekend

 

[aclac]

HI. I'd like to add "true bypass" relay to my diy 1176 revJ compressor, and... I understand, that I should use 2 relays, but might this been possible to get it work with only 1 relay (DPDT)? I'd like to keep it so simple as possible... aclac

 

[spacecho]

Hello All,

I've built 2 of these units in a Dual Case.

They all seem to work correctly, however on 1 channel the input gain is always full - regardless of the input pot setting.
I confirmed that the pot is wired correctly and gives correct resistance all through its travel (same as working channel)

I swapped the input IC's around in case one  was off but still the same.

Has anyone had this issue?

 

[gyraf]

Space,

Check that you have ground/0V on pot ccw, input signal on pot cw - and then, if your pot works, you will have variable level on the center/viper of the pot. Nothing else can really go wrong here, I think - it's a simple attenuation of the input signal (see schematic)..

Jakob E.

 

[aclac]

I finally get my new rev J- twins alive and needed to calibrate those. It was really hard to get easy or good calibration instructions to this rev J and so I made new kind calibration method. Much easier for me... need digital multimeter and output should connect to for example to mixer or some kind of that (to balanced input anyway).

First, you need to know... I have cheap DC- "VU- meter". Needed diode bridge and extra 1 kohm resistor to parellel with R51 (meter board) to show 0VU right.

1. Okay, run the unit for 10 minutes to stabilize components' temperature.

2. Make Q-Bias adj. Set ratio to 1:20, meter mode to OFF. Set release and attack fully CW, IN POT CCW and OUT POT 3/4 CW.

Then apply a 0dBu (0.775 Vrms) 1kHz sine wave to the input. Adjust IN POT get +1VU (0.869 Vrms) to the outputs digital multimeter. Start with the Q-Bias trimmer fully CCW. Then turn the trimmer CW until the digital multimeter reads 0VU (0.775 Vrms). Now the FET is sligtly in conduction.

3. GR Meter Tracking and ZERO. Set ratio to 1:20. Set meter mode to GR. Set input middle and output to CCW. Set release to fully CW and attack CCW.

A - With no signal applied, adjust VR55 (ZERO adj) so that the VU- meter reads 0VU.
B - Apply a 0dBu (0.775Vrms) 1kHz sine wave signal to the input.
C - Switch the meter mode to OFF (comp. bypass).
D - Turn the output level control until the outputs Digital MultiMeter, DMM reads 0dBu (0.775Vrms).
E - Switch the meter mode to GR.
F - Turn the input level control until the DMM reads -10dBu (0.245Vrms).
G - Repeat steps C to F until DMM show (0.775Vrms) on bypass- mode and (0.245Vrms) on GR- mode.
H - Leave the meter mode to GR.
I - Adjust VR54 (TRACKING) so that VU- meter reads -10VU.
J - Turn off signal.
K - Adjust VR55 (ZERO adj) so that the VU- meter reads 0VU.
L – Turn signal on.
M- Repeat steps I to L until VU- meter show right in both cases.

That’s it… so simple, and compressors work as old trains toilet.

BTW. What you think about this kind calibration steps?

 

[knight84]

Hi, I have read 30 pages from start and then read mnat's site about gyraf 1176. There it is told that gain level can be a problem in the original clone. Now I might be asking something asked frequently but I am asking for any offer or information about this.
I am using Gyraf's pcb and doing the electronically balanced option with lundahl output tranny. I am at the point of soldering the tranny. Should I do it as it is given or do any reversing or any other operation?  Thank you

Barbaros

 

[gyraf]

Best to build the original project as-is, and then tweak later - if you find you really need that.

Jakob E.

 

[knight84]

Thank you! I will do it as you have given

 

[Greg S.]

Does some one ever measured the Impedance forwards the primary side of the Lundahl 5402 at the 1176LN?
Is there a general methode for measuring the Impendance. I want to use different transformer, that's why I'm asking
THX

 

[gyraf]

Output stage impedance is very-low - and you CAN use just about any transformer you find.

However, it will off course sound different, and possibly give you alternative gains/impedances at your output.

I used the 5402 because that was the one of the handful we had at the time that most closely resembled the original rev#F's we had in the studio - according to common consensus among our engineers.

But as said, the circuit will drive just about anything - just make sure that you don't short-circuit the output if you use very-low-copper-resistance types, as the output drivers are not entirely short-circuit-proof.

Jakob E.

 

[SIXTYNINER]

hello
have a chance to get some sifam vu meter from a surplus store
the model is: R22AF
as showed in attached image

can be "adapted" for the g1176 ?

thanks in advance
S.

 

[weiss]

if it fits in your case, why not? what is your concern?