All things G1176 - the new "repost" thread.

[byoung]

I just finished up my Dual g1176, it seems as though it is working properly though I have yet to fully calibrate it. I am curious...I have used OEP in and out on Mnats board and it seems that the unit has about a +6db output ceiling. What I mean by that is that nothing goes over about +6db(haven't measured it yet, just going by my pro tools meter) it's a limiter in the truest sense....no matter how hard or soft I drive the input it limits output to the same range when fully maxed out to 10----about 6db. Is this right? I get quite a bit more output from my GSSL and my LA2a so it struck me as kind of low.

Maybe I could reverse my Output transformer for more output or swap a resistor? Anybody know?

 

[gyraf]

try calibrating it first. then maybe add the threshold trim mentioned above.

Jakob E.

 

[W DeMarco]

Beware of monitoring by ProTools. O DB ANALOG on my system equals around -14 db DIGITAL. Remember that you have it set up for headrooms sake. My G is a bit short on the output but there are several mods concerning this. One is in current discussion right above your post. I have chosen to leave it be for now and see if its something I can work with.

Will

 

[rbaker]

What if you bypass the unit.....is there plenty of gain then?

If so, then you'll want to do the mod discussed above.



I actually have a question about that for jakob or anyone else.

I ended up just replacing the 56k resistor as it was originally described before the trimpot suggestion came up. I put a socket in so I could change out resistors quickly. (the trimpot thing, no matter what I did was flimsy...I was going to put in a small perfboard in it but I think this was easier)

I ended up with 560k (10 times the normal) Is there anything wrong with doing it this way as opposed to the trimpot way?

 

[gyraf]

Is there anything wrong with doing it this way as opposed to the trimpot way?

I don't think it can cause any problem..

 

[raysolinski]

Okay guys..I need to call in the "big boys"...My G1176 is passing audio..nicely. I can zero the meter and the q bias changes the sound (if I turn the trimmer I can eventually get silence meaning the fet is closed)..but she's not compressing ..I read this thread and starting hunting...my voltages are way off in the control amp section...I checked and pulled every resistor..made sure the caps were right...Before r70 I have 30.1V After R70 I get 27.4 volts..perfect drop...after r62 I should get 15V or so but I get 25V..I checked r62...put in different verified 47k's....no change...My volts on Q15 are low by 10 volts....I get nothing on r61 (470k) at all..r62 (1meg) has the 25 volts one one side and O on the other....kirchoff's law, perfectly... but I can't find anything that throws the circuit off by 10 volts...obviously Q12 isn't functioning..it's has no voltage on the collector....could it just be a bad Q12? No shorts around it....??


puzzled as usual..

Ray

 

[gyraf]

Replace parts under suspicion?

 

[raysolinski]

I replaced resistors but they all were right to spec anyway..I am waiting for some replacement transistors..I think I will pull the transistors in that section and check voltages..it is almost like I don't have enough , or too much, current..I can't think of how else to explain dropping resistors that don't drop.
27 volts-47k resistor-24.5 volts makes no sense...(and the 47k is verified with two different dmm's)

Ray

 

[raysolinski]

I found it! A bad resistor in the gr amp section...put in a new one and voila..I have compression...now I have to bias adjust and set the tracking (which at this point is way off)...thanks Jacob!

Ray

 

[gyraf]

:thumb: :sam: :sam:

 

[khstudio]

[quote author="rbaker"][quote author="imo"]I had the best success with the 5457. It increases the threshold a decent amount [/quote]

I put the 5457's in and finally got around to testing it out. It definitely helped with the threshold level---I can get a better level out of it, but it's still compressing pretty hard.

Has anyone listened to the difference? This might be totally psychological, but I just remember the 245's being a little more....buttery...if that makes any sense. I'm not going to say that the 5457 sounds bad, AT ALL, I just remember thinking that I'd use the 1176 more than my distressor when I had the 245s in and now I'm not so sure.

[/quote]

Any more on this :?:

I know that different "Brand" components aren't equal... what brand did you use?

What BRAND 5457 did the "ORIGINAL 1176" use :?:

Thanks,
Kevin

 

[keefaz]

Hi,

In the G1176 electronically balanced circuit, I see that
the pin 4 (V-) of 5532 IC is connected to 0V rail and pin 8 (V+)
is connected to 30V rail.

Does that mean that we can power the IC with 0/30V
instead of -15/+15 V ? If yes, why does the manufacturer
datasheet say the maximum voltage is -22/+22 V ?

(sorry for the stupid question )

 

[joe-electro]

[quote author="khstudio"][quote author="rbaker"][quote author="imo"]I had the best success with the 5457. It increases the threshold a decent amount [/quote]

I put the 5457's in and finally got around to testing it out. It definitely helped with the threshold level---I can get a better level out of it, but it's still compressing pretty hard.

Has anyone listened to the difference? This might be totally psychological, but I just remember the 245's being a little more....buttery...if that makes any sense. I'm not going to say that the 5457 sounds bad, AT ALL, I just remember thinking that I'd use the 1176 more than my distressor when I had the 245s in and now I'm not so sure.

[/quote]

Any more on this :?:

I know that different "Brand" components aren't equal... what brand did you use?

What BRAND 5457 did the "ORIGINAL 1176" use :?:

Thanks,
Kevin[/quote]

The "original 1176" used a Teledyne FET marked "U2244". I'm lucky enough to have five original FETs. I've done exhaustive research trying to find any data on this part and the closest I can come is an FET made by Teledyne with the part number "U224-4". I'm guessing it's the same part. Point is, to my knowledge, original 1176s never used the 2N5457 (or 5458 or 5459) at all.

 

[gyraf]

Does that mean that we can power the IC with 0/30V
instead of -15/+15 V ? If yes, why does the manufacturer
datasheet say the maximum voltage is -22/+22 V ?

Yes, this is quite standard - the opamp dosen't care what we reference the voltages to, as long as it's in- and outputs are kept somewhere between the rails..

The -22/+22V simply means that you will have to stay below 44V max.

Jakob E.

 

[keefaz]

Thanks Jakob !

 

[Miska]

Hi,

can I use Lundahl LL1521 as an input transformer instead of LL1540? Apparently, there is no ground pin on LL1521...

Cheers,
Miska

 

[edanderson]

[quote author="joe-electro"]
The "original 1176" used a Teledyne FET marked "U2244". I'm lucky enough to have five original FETs. I've done exhaustive research trying to find any data on this part and the closest I can come is an FET made by Teledyne with the part number "U224-4". I'm guessing it's the same part. Point is, to my knowledge, original 1176s never used the 2N5457 (or 5458 or 5459) at all.[/quote]

http://jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/UREI-1176LNmanual.pdf

if you look at the various 1176 schematics, you can see that they changed from what they called the "DF60214Q" (which was usually a U2244) to the "urei 13-0027" which was either a U2244 or a house selected 2n5457/8/9 type part. i have a repair bulletin from urei that called for a 2n5457/8/9 as a replacement part for 13-0027, so it could be that most of the 1176s with 2n5457s were ones that had been repaired.

ed

 

[gyraf]

Our Rev#F's - purchased around 1987 - came with 2N5457 from factory..

Jakob E.

 

[Miska]

Bump

Hi,

can I use Lundahl LL1521 as an input transformer instead of LL1540? Apparently, there is no ground pin on LL1521...



Cheers,
Miska

 

[Guest]

I wonder if anybody can help me as I am completely confused and can't figure out whats going on wih my 1176.

It works great as a line amp but I can't get it to compress - did a search and theres lots of advice on how to check points 21 and 19 for Qbias voltage and to check voltage changes according to signal changes - the thing is as soon as I connect my digital multimeter to pins 28 (convienient 0v) and the other probe to either pin 21 or pin 19 the 1176 starts to behave strangely.

By strange I mean the meter (in GR mode which is normally still at 0db) drops to zero and can be moved by moving the release pot to CCW??!?!?

Passing audio through it gives a lower level distorted sound.

Removing the DMM or borrowed oscilloscope probes from the circuit bringsme back to normal operation (albeit without compression which is what I was trying to solve in the first place)

The voltages on the pins that I was supposed to measure are only moved by the action of the release pot.

So I'm confused - I checked that I have a proper ground and it was ok (getting 0 volts from mnats PSU as welll as +30 - 10)

SoI'm doing something very basic very wrong - any tips - before I tear out the little hair I have left.

I've built other stuff before - baby animal mic pre, Bo hansen DI, lots of guitar effects but I've never expeirenced this before.

/Taz