[BUILD] 1176LN Rev D DIY

[Biasrocks]

hello,

i did a search for "alternate resistors" btw. I'm totally new and I hate noise so i have read that vishay resistors will eliminate hiss. So here are the product details for a Xicon resistor in the hairball BOM.
If I convert this Xicon resistor to a Vishay, which of the following specs am I concerned with?

You're over thinking this, I would not call a REV D noisy.

Better to build it stock, get it working and then try some mods if you're not satisfied.

Stop reading tweakers forums and go with the BOM that Mike specified.

Regards,
Mark

 

[TheWolfman]

Very very almost there!

I'm just wiring up my output pot and following Mnats guide.It shows how to attach the ratio board to the output pot:

http://mnats.net/images/output_pot_two_shielded_wires_thumb.jpg

However I'm not sure what happens to the Shield at the ratio board end...is it just left free?

 

[sr1200]

yep... just gets covered up by the shrink tubing.

 

[TheWolfman]

Thanks SR1200! ;D

 

[TheWolfman]

It's....It's.....It's alive!!!!!

A very daunting moment indeed....but she powers up and theres no smoke,which has got to be good news!

I'm going to leave the calibration until tommorow....however I'm slightly worried about two things on initial inspection.Firstly the meter needle doesn't swing to zero when GR is selected like an 1176 should.Secondly it reads absolutely no input level on the meter but when you turn the output past 3 o'clock the needle flys to +1 as if it's self oscillating or something!

Should I be concerned?

 

[sr1200]

out of evey 1176 ive ever used from the ureis to the new UA's NONE of them shoot to 0 on the meter (especially when its not 0d or calibrated.  The unit has to "warm up" before it hits 0.  In fact, before calibrating. let it sit ON for about 20 min before you calibrate.  One OLD model we used to have in the studio wouldnt 0 for almost 30-40 min.  None of us ever looked at the meter anyway so it was a moot point, but it was still kinda funny, an hour into the session, it was 'yup, the 76 leveled out, time to go!' lol

wait till you calibrate before worrying about things.  Especially if you didnt pre trim the pots before you soldered.

 

[TheWolfman]

So the calibration process is beginning...cue 2001 Space Odyssey title sequence!

First strange thing I notice when running a 1K tone through the beast is that I can actually hear the 1K tone coming out of the machine and increasing in volume as I turn the input up!!

 

[sr1200]

perfectly normal.  This was discussed in an earlier.

 

[number2]

You're over thinking this, I would not call a REV D noisy.

Better to build it stock, get it working and then try some mods if you're not satisfied.

Stop reading tweakers forums and go with the BOM that Mike specified.

Regards,
Mark

thanks for the advice. Anyone who tells me I am over-thinking it, I listen to because I know they're right.

 

[TheWolfman]

OK so I'm trying to calibrate...All controls set as described in Mnats Video:

Input set to fully CCW

Attack set to 3

Release 7

Ratio 20

Meter +4

I get nothing on the meter at all untill output is turned to around -10 where the meter is pinned to past +3 and then if turned to about -9ish the meter actually 'ticks' bouncing between  -3 and past +3 at a rate of about 2hz!This stops when the output is set further to -6 where the meter sits at +2 and increases untill the output is set to maximum.

What is also strange is that as I raise the Input Level the Meter level then begins to drop,rather than increase.

This surely isn't normal behaviour is it?

 

[TheWolfman]

Just took a reading at R64,as on the schematic it looks like this is the best point to take a reading of  the Power Supply Section output.I get a reading of -9.8v is this in the right ball park?

 

[sr1200]

All your questions and more can be answered at: http://mnats.net/1176_revision_d.html

 

[TheWolfman]

@SR1200

Believe me,I have thoroughly trawled through Mnats entire site in order to find an answer to this albeit to no avail,hence I'm asking to be imparted with some wisdom from some of the audio demi-gods on this board!

The input attenuator doesn't appear to cause any actual increase on the level on the VU itself although I know the level is definetly increasing as I can actually hear the 1kHz tone coming out of the open unit!

 

[sr1200]

As far as the correct voltages at points, there is a schematic with the voltages listed on his site.

As far as the wiring goes for the meter, if you believe there is a problem with the metering, you can post a decent rez pic of your wiring so we can see whats going on there (if anything).

The calibration videos are pretty accurate (although i've kinda shorcutted the third one as far as setting the drop up a bit easier).

For calibrating, you want the attack either fully CW (all the way up) or off (when he talks about shorting the pad to ground to bypass compression, that would be when you click the attack to the off position instead of jumping the pad to ground)  anything short of fully up or off you're going to get a delayed reaction from any change you make internally.  which is why at around 50 seconds or so he says that the position of the attack knob is irrelavent (because hes got it out of circuit with the short to ground)  For those of us using the HAIRBALL kit with the switches and the "switched" knob for the attack, we turn it completely CCW (or off) for the first step in the calibration as stated in the video.  Your release should also be ALL the way up (CW) to avoid delays in meter response (when in circuit). (notice the settings he has on his unit around 1:50 of the first video attack and release all the way up)

Try it again with these settings, see if that helps. 

 

[TheWolfman]

Ahhhh yes,found the schematic with the voltages!

All appears fine until I get into the GR Meter circuit were Q13 measurements seem way off...there is not even a negative reading.

I have also checked the output on a scope and listening and the sine wave quickly distorts at a very low level into a saw wave and then into a square wave with loads of ringing as the output level is increased.It also sounds like the frequency response is all over the place as either the input or output levels are changed.

Getting worried now.... ???

 

[TheWolfman]

I will post some pics up...I've been pretty meticulous with the build and took things slowly and concisely and have triple checked all wiring but hey you never know!

 

[sr1200]

Before you post the pic, take readings at all your 2N's and list them.  it may help to see whats going on.

 

[TheWolfman]

Here are my readings for my trannies.

Does anyone see anything blatantly out of wack on here?

To me all the Transistors in the Meter Driver section seem well outside of their correct values on Mnats schematic:

INPUT SET TO -24 OUTPUT SET TO -24

COMPRESSION OFF

RATIO-20

RELEASE-FASTEST


Q1- E -0.4
B 0
C 0

Q2- E 0.9
B 1.7
C 0.6

Q3- E 1.7
B 11.6
C 1.2

Q4- E 0.9
B 4.3
C 0.4

Q5 E 2.9
B 24.8
C 2.7

Q6 E
B
C

Q7 E 4.2
B 14.5
C 3.9

Q8 E 14.5
B 29.9
C 14.1

Q9 E 3.4
B 16.5
C 2.9

Q10- E 16.4
B 29.9
C 16.4

Q11 E -0.3
B -1.1
C 7.2

Q12 E -0.1
B 4.8
C -1.7

Q13- E -2.0
B -2.6
C -2.6

Q14 E 11.6
B 29.9
C 11.2

 

[TheWolfman]

I have added the correct voltage values from Mnats schematic next to the values I've read just to make things clearer.It seems to me that Q11-14 are way off being within a tolerable level of the correct values.

What could this be?It seems as if I have R44 the front panel tracking adjust wired up correctly.....I'm a little baffled now I must admit.



Q1- E -0.4
B 0
C 0

Q2- E 0.9  1.05V
B 1.7 1.75V
C 0.6 0.54V

Q3- E 1.7
B 11.6 12.58V
C 1.2 1.15V

Q4- E 0.9 1.02V
B 4.3 4.2V
C 0.4 0.46V

Q5 E 2.9
B 24.8
C 2.7

Q6 E
B
C

Q7 E 4.2 4.54V
B 14.5 15.25V
C 3.9 4.02V

Q8 E 14.5
B 29.9
C 14.1 14.7B

Q9 E 3.4
B 16.5 17.07V
C 2.9 2.96V

Q10- E 16.4
B 29.9
C 16.4 16.53V

Q11 E -0.3
B -1.1
C 7.2 10.56V

Q12 E -0.1 -0.9V
B 4.8 9.28V
C -1.7 -1.52V

Q13- E -2.0 -1.04V
B -2.6 9.75V
C -2.6 -1.63V

Q14 E 11.6
B 29.9
C 11.2 12V

 

[TheWolfman]

Here's some pictures of the build also by the way:

http://photobucket.com/1176