Echo North
Well-known member
bdunard said:
Yep "normal" is shorting (keeping R44 or whatever it is, in circuit). When you un-short it, it's like lifting a leg a pulling it out which you only do for NULL ADJ.
[BUILD] 1176LN Rev D DIY
- Thread starter mnats
- Start date
Help Support GroupDIY Audio Forum:
Yep "normal" is shorting (keeping R44 or whatever it is, in circuit). When you un-short it, it's like lifting a leg a pulling it out which you only do for NULL ADJ.
Calibration step 3 question.
4. Set attack full CCW (off position). Set input control for +10dBu (2.44 VAC) at your output XLR.
5. Turn the attack control ON (Fully CW) and readjust the output level control for "0dBu" if necessary.
6. Now let's set the meter to display this 10dBu drop. When the attack is "off" (full CCW) and you see +10dBu at the output, set the meter to 0 by using the front panel zero adjust trimmer.
When I move to step 5 and turn the attack control fully on the output doesn't change at all from the previous setting using the input knob to set the output to 2.44 VAC. The fact that is says "if necessary" makes me think I'm not doing something right. By turning the Attack full CW it suggests that I should see .775 VAC "0 dBu" at the output when in fact nothing has changed. Am I interpreting this wrong?
4. Set attack full CCW (off position). Set input control for +10dBu (2.44 VAC) at your output XLR.
5. Turn the attack control ON (Fully CW) and readjust the output level control for "0dBu" if necessary.
6. Now let's set the meter to display this 10dBu drop. When the attack is "off" (full CCW) and you see +10dBu at the output, set the meter to 0 by using the front panel zero adjust trimmer.
When I move to step 5 and turn the attack control fully on the output doesn't change at all from the previous setting using the input knob to set the output to 2.44 VAC. The fact that is says "if necessary" makes me think I'm not doing something right. By turning the Attack full CW it suggests that I should see .775 VAC "0 dBu" at the output when in fact nothing has changed. Am I interpreting this wrong?
Echo North
Well-known member
bdunard said:
It's always necessary.
1. In and out @ noon (mid way), attack ON (full CW), 20:1, release fully CW. Jumper back in normal.
2. Feed STRONG signal, 0dB 1K. Should read -4db on your meter in + 4 mode.
3. Adjust output to read 0.775VAC on the output (pin 2 and 3)
4. Attack OFF (full CCW OFF position).
5. Adjust input so output XLR reads 2.45 VAC.
6. repeat to dial in.
IIRC your output ends up at about 9 o'clock and and the input at 2 o'clock if it's a true 0dB signal on the input.
Try looking at this for a different method:
https://www.youtube.com/watch?v=pgSWfsEzU40
Mike
After going through all the resistors on the pcb, meter and ratio board all seemed to be good. I used an iphone app to quickly put in the color bands to get the value and match them up with the MNATS schematic. All seemed to be fine. Although I was a bit worried because I did have two extra resistors but nothing seemed to be out of place.
I looked at the attack knob and found the culprit...I had C and A reversed on the attack knob. All seemed to go fine after this.
After the third calibration step I see that my input knob is almost exactly on the dot between 24 and 18 and my output knob is on the dot between 36 and 48 so I guess that seems to be in spec.
I'll test audio tomorrow when I get my other bracket.
Thanks for your help Mike!
I looked at the attack knob and found the culprit...I had C and A reversed on the attack knob. All seemed to go fine after this.
After the third calibration step I see that my input knob is almost exactly on the dot between 24 and 18 and my output knob is on the dot between 36 and 48 so I guess that seems to be in spec.
I'll test audio tomorrow when I get my other bracket.
Thanks for your help Mike!
hymentoptera
Well-known member
JingleDjango said:
Foil shield is generally considered superior to braid.
Foil is typically used in plenum (inside walls and cabinets), inside equipment, between racks, patchbays, and console, and anywhere a cable will not be moved around during use. It's usually easier to work too with since the drain wire is easier to solder to.
Braid is preferred anywhere a cable will get moved around, such as mic cable, instrument cable, etc. to reduce handling noise and prolong the life of the cable. Braided shield cables typically have thicker insulation as well, but is sometimes a pain to solder and often costs more than the foil shield type.
Hope this helps!
JingleDjango
Well-known member
My finished unit has been in use for a week or so. Sounds good. However, last night the meter lamp bulb went dark. The VU meter still works fine, just the lamp is out. I lifted the hood and noticed that the 5W resistor was now running cold. I don't have any voltages to share right now because it wasn't a good time for the lab coat yesterday while I was trying to track vocals. Mainly I was relieved to find that the compressor still works. Does it sound like the lamp is just burned out? Can anyone suggest a reason why this might happen after only a week?
hymentoptera, thanks. I have a about a hundred feet of this Mogami console cable: http://www.mogamicable.com/category/bulk/console/
An audio tech recommended it and it's really easy to handle but I was wondering if it would mean more noise/interference in my builds. One thing I noticed is it's a bad idea to put my laptop next to the compressor's left side (near the input transformer) or else you'll be met with a super high-pitched squeal.
hymentoptera, thanks. I have a about a hundred feet of this Mogami console cable: http://www.mogamicable.com/category/bulk/console/
An audio tech recommended it and it's really easy to handle but I was wondering if it would mean more noise/interference in my builds. One thing I noticed is it's a bad idea to put my laptop next to the compressor's left side (near the input transformer) or else you'll be met with a super high-pitched squeal.
hymentoptera
Well-known member
JingleDjango said:
What's the value on the resistor, or at least what are the color bands? And get those voltages. I'd like to know what the volts are between the PSU side of that resistor and ground. Bulb is probably blown due to over current or something. It's easy to check the bulb, just take it out and measure continuity with multimeter. If it's open then the bulb blew. Question is why?
Good stuff. A joy to work with. Solders like nothing else I've used. I have some of the ultraflexible miniature cable (W2490 I think?) and it's amazing that they made twisted pair in such a small size. Capacitance ain't so great, but that's typical for Mogami.
That cable will be fine. You can't go wrong with Mogami, although I'm becoming a bit of a Canare fanboy lately as it's more affordable and plenty fine quality for me. Laptop noise is probably the power supply. That's pretty common with computers. There's all kinds of wizardry required with switched mode PSUs and digital next to audio, stuff that's way beyond me. Just use whatever cable your comfortable with and keep the laptop somewhere it doesn't cause interference, you'll be fine.
Ok so having a bit of problem with my 1176 today. All was working just fine last night. I went down to do an overdub this morning and the 1176 is showing gain reduction on the meter but no audio is coming out of the out put. If I crank the output all the way up I can hear a faint distorted gtr signal. Any ideas as to what could have happened. Nothing has changed it just didn't pass audio this morning.
Echo North
Well-known member
bdunard said:
Has to be some intermittent connection. The terminal headers can be problematic. Give all of those wires a light pull and see if any fall out of the headers. Particularity the out transformer.
Something somewhere is loose.
Mike
Wasn't any of the terminal headers. It seemed to go in and out if it set...I pushed on the heat sink of the Q6 transistor and the audio output came back on. I figured it might be a cold solder joint so I touched it up and it seems to be working.
One other question I have is:
My compressor sounds heavier on the 4:1 ratio than the the 20:1 setting. Is it possible to have something simple wired backwards that might flip the order of the switches? Is there anyway to test my theory that knee is indeed harder at 4:1 than 20:1. Thanks!
One other question I have is:
My compressor sounds heavier on the 4:1 ratio than the the 20:1 setting. Is it possible to have something simple wired backwards that might flip the order of the switches? Is there anyway to test my theory that knee is indeed harder at 4:1 than 20:1. Thanks!
Echo North
Well-known member
bdunard said:
Ya sounds like a bad joint.
Your switch should be fine. Read this post for an explanation:
http://groupdiy.com/index.php?topic=29981.msg766956#msg766956
Mike
JingleDjango
Well-known member
Thanks, hymentoptera. I'll look into the bulb when I have the chance.
Ok, maybe that's what I'm hearing. I double checked everything and all seems fine...resistors are definitely correct.
However, When I use the "all-in" function of combining my ratio buttons my needle on my VU meter moves all the way to the right (beyond +3) and stays there but still moves left when compressing. Is that normal needle behavior?
However, When I use the "all-in" function of combining my ratio buttons my needle on my VU meter moves all the way to the right (beyond +3) and stays there but still moves left when compressing. Is that normal needle behavior?
Echo North
Well-known member
bdunard said:
Yup. All normal.
JingleDjango
Well-known member
This thing is a dream for tracking bass and vocals.
JingleDjango
Well-known member
hymentoptera said:
I have the compressor at hand to figure this out. In the attached image you can see that the bands are Red>Yellow>Black>Gold, but in this case the 'yellow' band is nearly the same colour as the gold but only without the lustre.
29VAC between the end of the resistor facing the PSU and chassis ground. Seems normal. You can see in the image that the plastic panel screwed into the back of the meter that houses the bulb is bowed away from the meter housing, presumably from overheating. The interior of the glass of the bulb has darkened such that it's difficult now to make out what's inside, suggesting burnout. I can confirm that the bulb is dead with my meter.
Attachments
Echo North
Well-known member
JingleDjango said:
red-yellow-black would be way too low. Did you get that from us???
JingleDjango
Well-known member
It's straight from the kit. To my eyes, it's black. I know it should be brown for 240Ω. There's a reasonable chance it's brown and I'm just loopy. Lemme remove it and test just to make sure. . .
Echo North
Well-known member
Should be red-yellow-brown.
That's the only 5W we even stock. Use an ohm meter and disconnect the lead from the secondary. Test the resistance of the resistor.
Are you sure you have the lamp powered from one of the 25V-ground and not 25v-25v?
Mike
That's the only 5W we even stock. Use an ohm meter and disconnect the lead from the secondary. Test the resistance of the resistor.
Are you sure you have the lamp powered from one of the 25V-ground and not 25v-25v?
Mike
JingleDjango
Well-known member
Aha! Yeah! Jeez. That's totally it. I'm surprised it even worked for that long.
