All things G1176 - the new "repost" thread.

[Echo North]

Hi,

This site has a great list of UREI schematics:
http://www.waltzingbear.com/Schematics/Urei.html

What we are looking at is the "Urei 1176LN series F, "Black face", push pull class AB output".  Particularity the input circuitry located on page one:
http://www.waltzingbear.com/Schematics/Urei/Urei_1176LN_series_F_page_1.htm

I believe adding the  "T" attenuator with the UTC O-12 clone is a great addition to this project, making it more like a true revision F.

I sell a T attenuator here:
http://hairballaudio.com/shop/product_info.php?cPath=21&products_id=33

Since this is the 3-deck non bridged pot that Purple uses, the wiring is a little different then on the schematic.  For wiring instructions you can have a look at the Purple schematic or just see Matt's picture:

The C-3837-1 connections are (not confirmed... please check my work):
Pin 2 (- from T attenuator)
Pin 4 (+ from T attenuator)
Pin 5 ( + to board)
Pin 6 (ground)
Pin 8 (- board)

Check the F input circuit.  I'm guessing you'll want to connect the + to pad 2 of the "input gain" and the - to pad 3 with a 270ohm resistor in parallel.

Not a pro here and I'm taking a stab at this by looking at schematics quickly, so for the love of god someone check my work! 

Mike

 

[casrec]

Hello all,
    A couple of things, first off, in the north American parts list, he changes the 6.8uf tantalum in C19,C20 for electrolytic. Is this suitable or will it cause problems? Secondly, I put this in the wrong section before but, I want to adjust the attack on the mnats board which I am guessing is the same as the original 1176 from 8usecs-800usecs to 8usecs-8msecs. Can I achieve this buy adding or changing the resistor between the ccw and wiper lugs on the pot. Also, how would I test the time of the attack. I love the fast attack of the 1176 but if I could l would like to make it a little more flexible. Any info would help!

 

[gswan]

The change from tantalum to electro won't make any difference.
The change for the attack I already answered in your other thread.
You need to change the pot to increase the attack time and keep the fast attack time the same (ie you are requiring a greater range from the adjustment).

To test it use a tone burst generator with a 1kHz sinewave.

 

[casrec]

Thanks gswan! And thanks for the answer again. I will give it a go and see how it works. Pardon my ignorance, but will going up 5k have a significant change or should i go up quite a lot, up to 50 or 100K? Or would reducing give a wider range of attack?

 

[gswan]

If you want to increase the range by a factor of ten you'll have to increase the pot resistance by approximately the same factor. It's currently 25K, so increase to 250K or 500K and see how it goes.

 

[casrec]

If you want to increase the range by a factor of ten you'll have to increase the pot resistance by approximately the same factor. It's currently 25K, so increase to 250K or 500K and see how it goes.

Cool! I will give it a go. Thanks a lot!
 
Brandon

 

[gg85]

Looking at the specs there's quite a difference between the BF245A and BF245C so I will be ordering a bunch of them asap. Is there any difference between the 2n5457 and the BF245A...is one more suited than the other or is it more a question of which one is easier to obtain?

 

[SIXTYNINER]

hello - "MNATS"
i got 1176 rev j pcbs from you  , looking for a vu meter ,
sifam apart , have you some other type of meter to suggest, and that
work fine with 1176 rev j?
let me know
thanks in advance
6T9R
ps
your pm box are full

 

[3nity]

You can buy a used PM1000 vu meter, i paid 25 aprox for mine and it has real ballistics...!!!
Or you can go here: www.surplussales.com they got nice meters there..

0.02 cents

 

[SIXTYNINER]

thanks 3nity
but where can i find that meter?
6T9R

 

[3nity]

i bough mine from Echo North...send him a pm hes a nice buddy.

 

[Echo North]

[email protected]

I have a few meters.

 

[3nity]

BTW the meter you sold me is the nice partner of 2 1176!!
;D

 

[Nikbeat]

Thanks I bought the attenuators from your site when I got the.
So guess I just need to check the urei site for transformer
Connections.
Plus follow the attenuator pic you posted. Thanks

 

[gg85]

Just wanted to check before I order some more parts from mouser...is it possible to do the SLAM function on the rotary version with a standard 2 pole 6 pos switch, or do i need to get one like the switch in mnats pictorial on his website...mouser number 105-SR2921F-25S?

Thanks

 

[living sounds]

I changed transformers on my dual 1176 yesterday and now one side of them is not compressing any more. Passing audio, but when set to GR it reacts exactly the same as in bypass. I've tried tracking the sidechain but I've had no luck so far. When I push the input all the way in, the meter reacts very slightly - not in the GR fashion, but like a normal VU meter. Which parts should I check (or replace), and where does the sidechain leave the main board and get back to it? I've tried looking at the schematics and checked plenty of the connections with a resistance meter, but couldn't find any faults. The opamp works, I've put it in the working other half of the compressor.

Thanks!
Gregor

 

[3nity]

look at your wiring! mine did it too but i realize one wire was broken!

 

[living sounds]

look at your wiring! mine did it too but i realize one wire was broken!

Yes, but I did that and couldn't find an error. It would be easier if I knew where the sidechain signal should be and then send a signal through it and trace it. From what I understand all the opamp does is feed the meter, correct? So it shouldn't even matter if it's in there. I've compared voltages on various components between the two channels, and they seem close enough. It must be the sidechain signal, but I cannot see where.

 

[living sounds]

Could someone please tell me if the opamp does anything else in there besides driving the meter? Thanks!

 

[3nity]

just driving the meter. TL071 does just that!