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

[evilcat]

That's because 0 dB FS (digital) is not 0 dBu (analog)!!! In our world of analog and digital 0 dB are not the same. Generally 0 Vu is somewhere between -20 and -18 dB FS. As 0 Vu = +4 dBu, if you need 0 dBu then try a signal from your DAW between -22 and -24 dB FS.
I know it's a little scary... Good luck.

Best,

Ben

 

[sl4zhz]

Start by turning off gain reduction.

With the meter turned on and your DMM set to DC volts, place the common probe on the transformer CT PCB lug and the test probe on pad 18.  What is your reading here?  Now place you test probe on the gate of Q1 and what is your reading here?

Let's start by fixing the Qbias.  Them move on from there one step at a time.

Mike

Hi Mike sorry for the late reply,
Probe on CT PCB Lug and Pad 18 with DMM on DC Volts read -2.26 VDC
test probe on GATE of Q1 is -1.60 VDC (approx)

http://www.youtube.com/watch?v=LyrXJjTclbo

 

[Chrome Heart]

So, Im trying to bias a unit for a friend... everything seems to work except I dont show any gain reduction when the unit is in +4 output during the Q bias adjustment. It shows it working in GR on the meter though, so it appears the unit is compressing. Any idea why I dont get the -1 db drop during Q bias adjustment on the output?

 

[jakearon]

I am trying to connect the VU meter for my 1176 Rev A build and have a question about connecting the top 2 connections (the red and green wire in the Hairball build).

The Red, Yellow, Orange and Black wires coming from my power transformer are connected to my PCB board via a terminal block (Black = AC, Yellow = AC, Red/Orange = Center Tap) mounted to board.  I now need to essentially "jump" off those wires to connect to VU meter and am seeing different ways of doing this in different photos.

It appears there are a few ways to do this and I was wondering if someone could please advise which way would be best in my situation described above.

A.  Some builds show a terminal strip mounted to side of chassis and from there wires split to then go to the PCB board, as well as to VU. 

B.  Some builds show the connection being made at the PCB board for the "jump" to go to VU.

C.  I'm also wondering if it's possible to "jump/split" these wires just using a solder connection and heat shrink?

Should I disconnect wires and add terminal strip to side of chassis to do it the way mentioned in A?  Is it technically correct to pull wire off of PCB board for split or can I jump wire by connecting an additional wire with solder before it connects to PCB board?

Any insight would be appreciated.


--
JaKe aRoN ~ 'Makin' it happen since 2013 ;D"

 

[Chrome Heart]

I use a barrier strip and tap the 24v from there.

 

[Chrome Heart]

In addition to the above problem in my previous post, the tracking adjustment does not seem to function. Ive goner over this board all day and cant find the problem. Ive even replaced most of the components.

 

[germoju]

In addition to the above problem in my previous post, the tracking adjustment does not seem to function. Ive goner over this board all day and cant find the problem. Ive even replaced most of the components.

one day my Q Bias doesn't work.... I decided to change the 2k trimmer and DONE ! Trimmer can broke... maybe try that...

 

[Chrome Heart]

In addition to the above problem in my previous post, the tracking adjustment does not seem to function. Ive goner over this board all day and cant find the problem. Ive even replaced most of the components.

one day my Q Bias doesn't work.... I decided to change the 2k trimmer and DONE ! Trimmer can broke... maybe try that...

Yep. Did that. Changed 'em all.

 

[Chrome Heart]

Fixed. Bad input 2N5457 FET.

 

[hymentoptera]

Fixed. Bad input 2N5457 FET.

Had you bought some extras from Hairball, or sorted your own pile, or did you just throw a random FET in there?

Just curious. I'm considering building a testing jig to pair some up is all.

 

[Chrome Heart]

Fixed. Bad input 2N5457 FET.

Had you bought some extras from Hairball, or sorted your own pile, or did you just throw a random FET in there?

Just curious. I'm considering building a testing jig to pair some up is all.

I had 2 pair. Both from Hairball. I have a testing breadboard that I made some time ago. Ill probably go back to matching my own.

 

[hymentoptera]

Fixed. Bad input 2N5457 FET.

Had you bought some extras from Hairball, or sorted your own pile, or did you just throw a random FET in there?

Just curious. I'm considering building a testing jig to pair some up is all.

I had 2 pair. Both from Hairball. I have a testing breadboard that I made some time ago. Ill probably go back to matching my own.

which did you go with? i've seen several ways to do this, IIRC. I'm thinking of trying one of these
http://stompville.co.uk/?p=112

 

[Chrome Heart]

Heres a  simple one

 

[hymentoptera]

Thanks, Chrome Heart.  That one looks pretty simple enough 8)


Back to alternate componants, is anyone building/built their Revision A using silver micas at C6 (6.8pF), C11 (10pF), and C16 (33pF) instead of the Kemet ceramics from the Mouser cart? Any thoughts from anyone on using micas or thinking about using micas here, pros, cons, thoughts, experiences, etc.?? Is it worth it? Will it have an effect on the sound? Any thoughts or the function of C6, C11, or C16? How would having a mica here or there affect things? Are any brand or style of mica cap to be avoided or is there a prefered manufacturer I should try to find?

All thoughts on the subject welcome. Thanks!

edit: the reasoning for looking into micas is that these three caps appear to be micas in photos of the insides of original bluestripes seen here on groupdiy in another thread.

 

[Echo North]

Changing caps in the audio chain will ALWAYS change sound.  People tend to think mica caps add "sparkle" which may be a good or bad thing.  Some people love it, some people hate it and a lot never hear the different.  In the same way WIMA caps have a huge effect on sound that some people dig and "warmth" and others feel is disgustingly "muddy".

I'm generalizing a little.  But if you're way into dialing in your sound I would consider you put sockets in the pads of the audio chain caps and try EVERYTHING.


Also, if you do you must report back with your findings! 

 

[Curran]

got my replacement meter last week and was finally able to pop it in the other night. Re-did my Q bias, and null adjust, the meter tracking "SEEMS" to be spot on with NO adjustment, this is the 2nd unit I have built and have had the same end result, the meter seems to track the 10db drop right away and I done need to adjust anything . HOWEVER, I do hear a crackling or clipping in the signal of the 2nd unit when I really slam some dynamic clean strat into it. is there something wrong? the 1st unit I built does not do this when I put it to the same setting and signal chain. any ideas would be helpful!

P.S. Mike, do you want me to return the faulty meter for you to rebuild or something?

 

[jplebre]

HI guys

I've been scratching my head for several months on this. It's actually a rev D, but on Rev d no one seems to have heard of this.
However, I heard reports of symptoms here but no conclusive resolution.

My attack pot does bugger all :S the unit seems to be stuck at about midway "fast" attack setting regardless of the potentiometer.

All is measuring fine, continuity fine. I think it may be either a component failing due to something else or some really obvious problem that a lot of people have done (several people comment there's little variation on their clones - which is not how a 1176 behaves)

Any insight or clues?

Rectification at the diodes is fine, voltage at qbias reads about -3v, about -2.6v at the gate.

 

[hymentoptera]

...My attack pot does bugger all :S the unit seems to be stuck at about midway "fast" attack setting regardless of the potentiometer...

My first thought is a bad/wrong value cap, possibly C27 or C22? Wrong value resistor or pot, or wiring/trace problem? Something screwy in the gain reduction amp?

 

[jplebre]

Hi Hymentoptera. Ty for the replies.
C27 swapped. C22 not swapped but I guess I should. Problem happens in both units.

Any alteration to the wiring I have now causes the unit to flip (no compression, no sound, distortion, etc.) pretty confident it's fine according to the guides.

I've tried to probe continuity against the schematic. I can confirm that all traces are there. What I can't confirm is if they are shorting with anything else, so a bad trace could probably be it but I have/I don't know of any good method to test this against all the possibilities. :S tips?

GR section voltages match the default perfectly. On a scope, I can see the rectification of the waveforms above treshold after the diodes correctly, and they respond to changes in release, but not to attack.

:S stumped big time

 

[mrtomcat]

Hi there,

I just started on my 1176 rev a and while I am no stranger to wiring and so forth, this is my first DIY project and I want to be extra careful... so this might sound stupid but when testing the Power Rails do I test without a power source connected or do I actually have to plug in the unit? And if so is there something else to check other than continuity between the case?
While I have been following the manual carefully and believe all is fine, I am a little scared that once I plug this baby in I get shocked...unfortunately the manual doesn't really go into depth on how to test and what to be aware of.

I would truly appreciate some details here.

Thanks!