All things G1176 - the new "repost" thread.

[kruz]

[quote author="Gachet"]I will never get a a friendly and decent answer in that forum?GRRR

ciao[/quote]

jakob's answer was very friendly and more then decent.
you just have to do your job instead of asking for a personalized help just for you..
You have an enormeous amount of free knoledge here, you just have to read it. It's DIY!

 

[clorax hurd]

I'd like to ask, if it's possible to fit this thing into 1U case and if anybody tried it.... or does it have to be 2U? (to me it seems like it would fit in 1U, but i've seen more photos of this unit finished and it was always 2U)

 

[kato]

[quote author="clorax hurd"]I'd like to ask, if it's possible to fit this thing into 1U case and if anybody tried it.... or does it have to be 2U? (to me it seems like it would fit in 1U, but i've seen more photos of this unit finished and it was always 2U)[/quote]

It will fit in 1U if you can find a small enough VU meter.

 

[JRE Productions]

[quote author="clorax hurd"]I'd like to ask, if it's possible to fit this thing into 1U case and if anybody tried it.... or does it have to be 2U? (to me it seems like it would fit in 1U, but i've seen more photos of this unit finished and it was always 2U)[/quote]

I also had it in a 1U rack when I first built mine. But there is only enough room for the knobs of a single unit.

I actually have thought many times about trying to rack everything I build into 1U size cases. I can get more stuff in my racks that way!

Joe

 

[clorax hurd]

[quote author="kato"]It will fit in 1U if you can find a small enough VU meter.[/quote]

It seems that sifam AL19WF would fit into 1U. will try it

JRE Productions: good to hear that! thanks.. .

 

[kato]

Hmm, it never occurred to me there was a sifam meter that would fit.

That's a great idea - i've always thought 2U left a lot of empty space for a single channel 1176.

I think I'll try that too.

 

[al_p]

Hi Everyone,

Well it's been almost 2 years in the making, but i finally had the time to finish my G1176s. I've got some issues with them...maybe. The first thing i checked were all the transistor EBC voltages and they seem to be within norms based on several measurement sets I've viewed here. +30 and -10 are looking good. The unit seems to calibrate properly following Jakob's procedure and the original UREI manual. The unit passes audio and compresses, and all controls seem to do what they should. The unit passes audio in bypass, with the FET in and out of the circuit. The line amp sounds good. In bypass I can get quite a clean signal through it in excess of +3dB VU.

My problem is this. The comp really crushes almost any signal at around 1-2 on the input, and even with the output at max, I can't really get anything above -5 dB VU. I thought I had made a mistake, so I went back and re-read this entire thread and found that a couple people had reported the same behaviors. Kdawg's posts seem to describe my exact situation. Is this normal? the controls don't really respond the same way as the other 1176s I have in the studio. [blue badge, rev F, rev H]

I am using Chef's board built to Jakob's specs, transformer balanced i/o with the romeo trace cut. The first thing I'm going to try is to rewire the output to 1:2 as i am currently running 2:1. This should help my output gain problem. But I'd really like it if the input control would respond like my other 1176. Right now it's really touchy and I feel I can't make adjustments with any precision as I am jockeying the input control between 0.5-2. Also, from a familiarity standpoint I'd like to be able to blindly [deafly?] set it at the good ol' 10 and 2 o'clock as a starting point. I'm just really used to being able to barely tickle the signal with compression at those setting.

I've tried about 4 different matched pairs of FETs and after calibration, the unit reacts the same. BTW, I am interfacing with equipment operating +4dBu @ 600 ohms in and out.

so to summarize:

1. Is what I've described normal?
2. Is there a way to decrease the input sensitivity [input pad, rewire input tranny?] that makes sense and will keep Q1 happy.

thanks for reading.

 

[kato]

AL, Might it be something as simple as changing your input pot from a linear pot to a log pot (or maybe the other way around.)

Just a wild guess, Kato
Good luck!

 

[al_p]

Hey Kato

Well, i've got a log pot in there now. If I swap it for a linear, I'll be getting more signal at the start of the rotation, which is opposite of where I wanna go...thanks for the idea though.

 

[imo]

AL,
I have the same problem. I have rewired the output transormer and it does help with makeup gain, as well as trying a number of different fets. It is the input gain, and the clean headroom when compression is engaged that is the problem. The unit sounds great, the compression sounds great, there is simply too much of it<G>. I have been poking around at ideas to somehow buffer the compression level but nothing has worked so far. I will post any success i have and would appreciate if you make any headway as well
Ian

 

[al_p]

Thanks for the report. I was looking at the oringial rev F schematic, and was wondering if anyone tried wiring the input as UREI did, with a T bridge attenuator before the transformer. I don't know if the LL1540 would be suitable in this configuration. I can't seem to find the impedances in the data sheet. Does anyone know? Am I blind?

 

[mfdu]

got some voltage problems in one of my units.

it's using OEP input and output trannies, everything was measured as it was built.

the problem with unit 4 is signal oscilation at low input levels. remove the BF245 and it passes clean signal without a problem.

unit 3 is fine (and sounds fantastic compared to the pair of electrically balanced units i built previously)

have tried replacing Q1, Q2, Q3 and Q4, but no improvement. unfortunately when using my solder wick, the actual PCB tracks came up and i have had to do a couple of point-to-point bridges. but the voltages remained the same with the replacement components.

i have provided voltages to illustrate :

------------- E ---- B ---- C
Q2 unit 4 : 0 : 0.5 : 1.3
Q2 unit 3 : 0.5 : 0.9 : 1.7

Q3 unit 4 : 0.7 : 1.3 : 17.8
Q3 unit 3 : 1.1 : 1.7 : 11.8

Q4 unit 4 : 17.8 : 17.9 : 29.2
Q4 unit 3 : 11.4 : 11.8 : 29.6

the three pins of the voltage reg (7824) are perfect on both units. i can't understand where the 17V on Q4 comes from.

(do you require the rest of the voltages? please advise)

so, my question is this - what feeds voltage to Q2, and where has it gone (there ain't no visable shorts)
also, what could be the cause of the raised voltage at Q4? i'm guessing they're linked. . .

i'll continue working on it, obviously.
but if anyone has any tips, i'd love to hear from yerz!

chris.

 

[al_p]

So for those who are interested, I rewired the input like the original rev F. I found some ganged pots in some routing modules that came from a UA console. They look like the same ones UREI used in rev F and other TX input versions of the 1176. I didn't have a UTC 0-12, the closet thing I had was a hammond 850G, wired as 600:150. I also did the Chef rewire of the output TX so i'm running 1:1 at the output...

Well, it's closer. The input pot makes more sense. The 850 actually sounds pretty damn good. Heavy and soft. It seems to tame the really fast transients that sometimes sneak past at extreme setting. I'm probably going to go for the 1:2 rewire on the output, as I have it at max to get 0 to +3dBVU.

Getting there.

 

[Robin Reumers]

Hi,

I'm looking for my last parts for my 1176, I'm looking for a main rotary switch, preferably at farnell (because I only need to order there for my last parts), can anyone give a good link with one that should work, because I'm not sure which current rating I need?

Robin

 

[rbaker]

I might be totally missing something, but i thought I'd ask anyway...

On both the gyraf parts list and Greg's part list it has a 220p 50v polyester cap...(2 of them) I believe the place on the board is marked 200p. I assume that this is where it's supposed to go (just trying to make sure I didn't put something else in it's place)

 

[gyraf]

yes.

 

[pxpx83]

I skimmed through most of this thread, but I couldn't find the answer I was looking for.

Where is the easiest place to grab power for a power led? Would it be ok to use the power that lights the VU meter? I'm using the mnats version of the 1176 pcb.

Thanks!

 

[enthalpystudios]

[quote author="al_p"]So for those who are interested, I rewired the input like the original rev F. [/quote]

That sounds awesome! I'm really interested in how you did this. I have stancor wf30's on mine right now, basically utc a20 clones... which is the larger core version of the O12, basically.... same hookup options.

Right now it's 600:600, and I think thats a big part of my problem. But would you mind sharing how you hooked up the pot's? And how many decks would one need?

I also have some 2, 3, and 4 position greyhills that I could probably use if I can't get a hold of a pot that works, and just kind of have 12 positions.

Anyway, very interested in hearing that someone with the 'too much gain' affliction found an idea.....

I think that if I can hammer these out and get them working how I'd like, I'll probably build the next couple with electronic in lundahl out.... should contrast well with the utc in/oep out that i have now

thanks for sharing

billy

 

[sintech]

pxpx83,

You can use the 36v marked VU LAMP for LED's no problem, Just gang 2-3 (standard 5 mm) in series and add a 1/4 watt 1k resistor also in series on the positive side. LED's will be fine with that voltage but need a current limiting resistor otherwise they smoke!

This could work ok for a Power Led also. If you do a search for "limiting resistor" you'll find all you need.

 

[pxpx83]

Thanks sintech.

I've run into some trouble trying to calibrate my 1176. I've tried adjusting the q-bias, but turning the trimpot has no effect. I also tried adjusting the zero adj trimpot, but this has no effect (meter is pegged in GR mode).

I'm suspecting the the two trimpots are at fault. Ajusting the trimpots fully cw and cww has no effect on the voltage I see on their legs. The trimpots have 3 legs and i'm only seeing voltage on 2 of the 3 legs (the other 2 trimpots have voltage on all 3)

Any other ideas?