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

[dandeurloo]

oh man I want a pair of these!

 

[Echo North]

Has anyone noticed a drift in the VU meter?  This has barely burnt in, possibly it will loosen up some over time?

The early revision units with the discrete meter circuit drift.  I like to have them on for a good 20 min before calibrating or using them.

 

[Randyman...]

Bump for Echo/Mike for my post on the last page (last post on page 45) about swapping C1 & C8.  Any input?

Thanks!  8)

 

[Echo North]

Bump for Echo/Mike for my post on the last page (last post on page 45) about swapping C1 & C8.  Any input?

Thanks!  8)

Oh man, I'm the wrong person to ask about cap types.

IIRC C1 isn't in the signal path, it's involved in the Q1 bias.  C8, C2, C10 and C7 are in the signal path, so people like to use the orange drops for their "sound".  If you want to keep the signal amp all orange drop, then you'll want to swap them.

Switch them and see if you can hear the difference.  Actually maybe I mean "hear" if you can hear the difference. 

Mike

 

[diyfanatic]

hi guys,

small question here as I didn't found an answer in the thread!

- C11 is listed as 10pf on the BOM and on the schematic but 47pf on the pcb, wich value is correct? (I guess 10pf)

I've found that on the mousser cart from Hairball C18 wich is 47uf is listed twice...

cheers.
Jr.

 

[MicDaddy]

hi guys,

small question here as I didn't found an answer in the thread!

- C11 is listed as 10pf on the BOM and on the schematic but 47pf on the pcb, wich value is correct? (I guess 10pf)

I've found that on the mousser cart from Hairball C18 wich is 47uf is listed twice...

cheers.
Jr.

10pF @ C11, I also ended up with an extra 47uF electrolytic (what I get for not checking off the BOM) also had an extra heat-sink, and a .001uF (1000pF) Wima..  ??  oops ;D

 

[diyfanatic]

so you use the 10pf? no problem here?

(what I get for not checking off the BOM)

same here I was in a hurry so I went blind on this...

 

[MicDaddy]

so you use the 10pf? no problem here?

Yes, the BOM called for the 10pF @ C11 which is what I used... mine is working great!  

In all instances that I saw, while digging through this thread, Mnats will say (not verbatim I am paraphrasing) 'Follow the current BOM, or the BOM specific to the REV of pcb you have'  my pcb was 1.2.5 and the BOM called for 10pF @ C11 which is what I populated with... (though the screen on the pcb did call I believe for 47pF)

I chose the clip on heatsink for the LM-7824 only because I didn't want to deal with the hardware....  no overheat problems on a 24hr+ burn in

 

[diyfanatic]

thanks dude!
back to soldering!

 

[MicDaddy]

Question for anyone with units up and running...

With the unit powered up, do you hear the slightest 60Hz physically coming from the AC toroidal?  

My unit sounds great and I've no hum in the audio, but outside of box with no ins/outs just power to the pcb and meter.

I stick my ear very close to where the transformer resides inside and hear a very subtle tickingish 60Hz (at least what it sounds like).

Curious if this is an issue to be concerned with, both secondary show 29V~

 

[snooty]

So I replaced as many film caps as possible with Sozo handwound caps....C1,C2,C8,C13,C14,C15 ...there are still the two 1uf Spragues in there. 

My other Rev A I left the Sprague and Wima caps in so I can compare my two units.  The Sozo's have a more laid-back sound, not nearly as aggressive(distortion) as the Sprague and Wima caps.  Which is good and bad depending on what you are going for.  The Sprague and Wima caps add a nice distortion and push the sound very upfront(presence).  On acoustic guitar the Sozo is much more clear yet still solid,  very smooth with more depth.  I have some sessions over the next couple weeks so I'll test more with mixing and tracking.

I ran the Sozo's with a sound loop for 12 hours...they will probably break in more.  I noticed the Spragues & Wima's also sounded more round after the unit was used for a week.

You can really change the sound of this compressor by just changing the brand of signal caps.  I originally built the 1176 revA to have an aggressive pair...now I've got options...though don't want to get obsessive over this!

 

[EHOFFA007]

Just finishing up this unit. Powered on, No smoke
Passes audio with low gain and the T-pad has no effect on input level. is this normal before calibration?
Output pot is working and I get very little meter movement only at very high output gain.
triple checked wiring from xlr-tpad-input tx-pcb......looks good.
Maybe a bad t-pad? just a shot in the dark :'(
Thanks Ya'll!

 

[evilcat]

What do your voltages say before and after your T-pad ?
If I remember correctly, you should have the same voltages when the T-pad is at the max. And then lower output voltage than the input when you lower your T-pad.

Ben

 

[Stagefright13]

Doubt the T-pad is the problem. I broke one last year and glued it back with epoxy. Still works perfect. Unless it's not wired right. Did you do any calibration yet? The bias adjustment is wickedly important or your compressor will not work.

John

 

[EHOFFA007]

What do your voltages say before and after your T-pad ?
If I remember correctly, you should have the same voltages when the T-pad is at the max. And then lower output voltage than the input when you lower your T-pad.

Ben

with a .775v signal i'm getting same on full throttle and slightly lower .771 at off position(not sure if thats the proper decrease. not getting anything on tranny out. I think I have a problem in the preamp section. what should I be seeing at the transformer output voltage wise?
Thanks for the help!

 

[bieckmusic]

Hello, I'm super excited to be almost done with my 1176 Rev A (the end of the beginning).  With the full hairball kit and the BOM from Mouser, Mnats board.  It's been a real educational experience using all of the wonderful resources that are available and the wiring diagrams.  Also, I used some YouTube videos explaining circuit wiring and components.

I have a quick question though;

c27 is listed as a .012 uF capacitor but in my bill of materials I have a .01 uF 100Volt supplied and left over.  Apparently this is the cap for the Attack Potentiometer.  Will the .01uF work, or should I try and find a .012 uF?

Thanks so much!  I'm very inexperienced, so apologize in advance, I suspect I will be back on this site in a few days needing some troubleshooting help...  (Maybe not though 

bless, greg

 

[MicDaddy]

c27 is listed as a .012 uF capacitor but in my bill of materials I have a .01 uF 100Volt supplied and left over.  Apparently this is the cap for the Attack Potentiometer.  Will the .01uF work, or should I try and find a .012 uF?

This is on the attack pot correct?
I used the .01uF that came with the mouser shopping cart (Hairball). 
Not sure if the change would even be perceptible? 

I would appreciate anyone's comments regarding this.

 

[Echo North]

Mouser didn't carry an appropriate .012uF cap so I subbed in the .01uF .

There should be no problem.

Mike

 

[MicDaddy]

Hey Mike,

Should I expect any (very slight) mechanical 60Hz from the toroidal?  The audio sounds fine, no hum there.  
Physically (with my ear directly above, 1"+/-, the power transformer) I can hear a very faint buzz out of the transformer.

Thanks

 

[Echo North]

Have a read here:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1247693407&openfrom&2&4

Normal, but also make sure she's locked down good.