[BUILD] 1176 Rev A - Back to the beginning...

[Rob Flinn]

well, I did the Q bias immediately after power on, but waited for 30 min before doing the zero adjust and GR tracking adjust, should be ok - if not, I can always come back to it...

I guess if your comfortable with the Q bias point possibly not being right then that's ok

 

[evilcat]

Hi guys !

I'm doing some research before ordering the components and, here's a thought (I'd like your advices) :

Would it be a good idea to use carbon comp resistors for the preamp and line amp sections, and good precision (like 1%) metal film for the rest of the circuit ?
Does the audio passes through other sections where I can put carbon comp or carbon film resistors ?

Thanks for your advices.

Best,

Ben.

 

[ilfungo]

Hello Ben
I just finished the fourth 1176
this is the first carbon composition resistors consist of everything (everything, including the gain reduction circuit)
The difference is striking, the compressor sounds so wonderful ;D

 

[canidoit]

Hello Ben
I just finished the fourth 1176
this is the first carbon composition resistors consist of everything (everything, including the gain reduction circuit)
The difference is striking, the compressor sounds so wonderful ;D

How would you describe the difference?

 

[ilfungo]

compression is the same as if everything is softer and warm ....
I feel much less the action of the compressor, and the highs are much less sharp
sorry for my English ...

 

[evilcat]

Hummm, very interesting. So, if I understand, the compress is less agressive, isn't it ? Your other compressors are all metal film ?
The thing is I'm looking for "mojo" and I'd like the compressor to be thick and agressive ! What would you suggest ? Could you post some samples to compare ? That would be wonderful !
Anyway, thanks for your reply.

Ben.

 

[phatmateo]

I'm curious to see if there really is a difference instead of a "how they used to do it" placebo effect.  I'm building two 1176 Rev D's.  One will have all carbon comps in the preamp and line sections.  The other will use all metal and carbon film in those sections.  I'm leaving the rest of the sections metal films since I don't want any problems with calibration.  I will AB them and let you know what I find.  Maybe I'll post some recordings if I find the time

 

[evilcat]

Great !!!
How would you dispatching metal and carbon film ?

 

[phatmateo]

I would do all metal film, but I don't have all of the higher values in metal film(1.2Mohm or higher).  The majority of it would be metal film so I didnt think it would be a big deal

 

[evilcat]

While studying Rev A schematic on JBL site, I've noticed that Mako removed R31 (3.9k) and C13 (0.001µF). Why that ? For what purpose ?

Another questions : 1 - how do I match Q12 and Q13 ?

                          2 - I've read that I should have 0.00V between TP10 and TP11. Are there only test points ? How do I adjust them ? With R71, R44, R75 ? Do I need them while calibrating ?

                          3 - does anyone have put R71 on the front panel for "0 adjust" ? Is it this "0 adjust" that we usually found on front panel compressors ?

                          4 - and finally, what about the "R-OPT1" on the ratio board ? Does anyone have tested yet ? Would it be a trimmer for the threshold ? If yes, does a 100K trimmer would do the trick ?

Thanks

Ben

 

[ChrioN]

I'm curious to see if there really is a difference instead of a "how they used to do it" placebo effect. 

 

[evilcat]

While studying Rev A schematic on JBL site, I've noticed that Mako removed R31 (3.9k) and C13 (0.001µF). Why that ? For what purpose ?

Another questions : 1 - how do I match Q12 and Q13 ?

                           2 - I've read that I should have 0.00V between TP10 and TP11. Are there only test points ? How do I adjust them ? With R71, R44, R75 ? Do I need them while calibrating ?

                           3 - does anyone have put R71 on the front panel for "0 adjust" ? Is it this "0 adjust" that we usually found on front panel compressors ?

                           4 - and finally, what about the "R-OPT1" on the ratio board ? Does anyone have tested yet ? Would it be a trimmer for the threshold ? If yes, does a 100K trimmer would do the trick ?

Thanks

Ben

Anyone ?

 

[phatmateo]

1.  Google is your friend:  http://www.nrgrecording.de/html/fetmachting.html
Or just buy them for $10 at the hairball shop in white market
2.  You need them while calibrating the meter circuit.  Look at mnats videos on youtube
3.  I'd advise you to put R71 on the front as well.  Its a lot more convenient
4.  No idea what that is.  What ratio board are you using or are you just looking at the schematic?

I think people didn't reply very fast because most of these answers can be found by searching the forums

 

[evilcat]

1. Thanks man, it's a good trick ! As for Hairball, they "only" provide 2N5457.

2. I have looked at mnats videos many times, but I still don't see TP10 and TP11. The only procedure when you have to measured 0.00V is on R74 while calibrating the discret meter circuit. What am I missing ? ???

3. Thanks, that's what I thought.

4. I don't have the boards yet, I've bought them last week end and waiting for them. I've just saw that on the picture of Mnat's white market post. Some people in this thread were wondering the same thing and I wanted to know if anyone have tried it yet. I think I will.

Be sure that I've already done research before posting a question : I don't want to make you, people, wasting your time and thinking that I am a stupid, lazy beginner ! 

 

[phatmateo]

TP10 and 11 are just more convenient test points for R74(if I remember correctly), as shown in the video.  If you look at the rev a schematic, you will see they are connected

 

[evilcat]

OK, thanks !

 

[0dbfs]

Hi,

I am preparing to wire up a couple mnats RevA boards (board revision 1.0, 09-09-08) with the hairballaudio EA-5002's, and mnat's rotary meter & ratio boards.

I thought that there were previously issues identified with the output transformer wiring on this version of the board but can't find those references at the moment. After metering the EA-5002 & the PCB while comparing against mnat's PDF / schematic it appears that the schematic and self-etch PDF in mnat's docs is however accurate. I'm not sure about the silk on the PCB at the moment because that has been covered by the connectors.

If anyone can confirm or deny this (or even offer additional information), I would greatly appreciate it.

In addition, If anyone could confirm the wiring pinout on the EA-5002 I would also greatly appreciate that as well. Based on the color code of the EA revision, it also appears to be historically accurate WRT to the original 5002 (at least as per the JBL Rev-A schematic).

Thanks in advance!

Best,
jonathan

 

[dmp]

Hi Evilcat,
The omission of R31 and C13 is an interesting observation. I don't know why they would be dumped, since they provide neg feedback for the line amp. The values you said (3.8k, 1nf) are odd, as they would form a 40kHz rolloff high pass filter (I think). I can't read them very well, as the schematics in the URIE_1176LNmanual.pdf are hard to read, so maybe the values were different.
The schematic for the Urei 1176 original "blue stripe" on waltzing bear does not show R31 and C13.  But I've noticed other discrepancies from the waltzing bear site, particularly the rev D schematic, vs the manual version / mnats version, so I am not sure how accurate those versions are for the different revs. 
The 1108 preamp board has a similar feedback loop, but the component values are 8.2k & 6.8uf, which is a 2Hz rolloff high pass (which makes sense to block DC, but allow negative signal feedback). I just built a 1108 and it works with the 8.2k / 6.8uf values.
I'm hoping to make a revA so if you try putting in R31 & C13 I'd be curious for you to report what you find.
Dan

 

[living sounds]

Hummm, very interesting. So, if I understand, the compress is less agressive, isn't it ? Your other compressors are all metal film ?
The thing is I'm looking for "mojo" and I'd like the compressor to be thick and agressive ! What would you suggest ? Could you post some samples to compare ? That would be wonderful !
Anyway, thanks for your reply.

Ben.

I second that, could someone please upload a file comparing metal film to carbon comp with everything else being the same?

 

[Rob Flinn]

with regards to R31 C13, can I suggest you look back a few pages where this is all discussed. 

Go to the groupdiy google mail account where I have sent the full 1176 manual.  Stuff your boards as per the digram with REV A handwritten on the top.  Makos baords are designed round the diagram marked ser 101-125.  The REV A diagram sounds much better & is much more stable