[BUILD] 1176LN Rev D DIY

[Scrappersa]

Wow, I can build a freaking compressor but I can't wire a cable correctly. Just to give a heads up to anybody else who may encounter a compressor or piece of hardware that completely sucks the bass out (e.g. low cut/high pass filter/unintentional asshole), the problem was my input cable. I was running the compressor into my patch bay using an XLR to 1/4" TRS cable that was wired incorrectly causing phase problems. The compressor seems to be working correctly. I'm going to try calibrating it tomorrow and make sure that everything else is functioning correctly before I get my hopes way to high, but for now it sounds great!

haha i have made that simple mistake a few times. i blew an avalon 747 before i found out too 

Oh man, that must have been brutal!

How subtle are the attack and release functions? How about the difference between +4, +8, +12, and +20? I can definitely hear All mode, but everything else seems super subtle. I almost can't tell if they're working or not. All mode is pretty crazy though.

 

[Soundmugician]

Wow, I can build a freaking compressor but I can't wire a cable correctly. Just to give a heads up to anybody else who may encounter a compressor or piece of hardware that completely sucks the bass out (e.g. low cut/high pass filter/unintentional asshole), the problem was my input cable. I was running the compressor into my patch bay using an XLR to 1/4" TRS cable that was wired incorrectly causing phase problems. The compressor seems to be working correctly. I'm going to try calibrating it tomorrow and make sure that everything else is functioning correctly before I get my hopes way to high, but for now it sounds great!

haha i have made that simple mistake a few times. i blew an avalon 747 before i found out too 

Oh man, that must have been brutal!

How subtle are the attack and release functions? How about the difference between +4, +8, +12, and +20? I can definitely hear All mode, but everything else seems super subtle. I almost can't tell if they're working or not. All mode is pretty crazy though.

make sure your sending it a decently hot signal, and use the input attenuator like a threshold control, the more you turn up the input the more compression you should see, and the higher the ratio the faster it should compress when turning up the input. Also with the release on fully slow the needle should take a decent amount of time to recover ( ie if you turn the input up real high and get it to compress then turn it down ). when the release is set to fully fast the needle will recover pretty fast, the attack is harder to judge like this but there will be a little delay before the needle responds when compressing with slow attack, and with fast attack the needle should have no / very little ( in ms ) of delay. Also make sure when your trying to check the attack/release your meter is in gain reduction mode.

 

[supiarmando]

Hi there,

I have a little problem with the 2N3708 for my Rev A. BOM asks min. hfe 250 for some transistors. But I measure none higher than 220 hfe. is this a problem?

measure ment is done with DMM @ 10uA and VCE 2,8V.

Any help would be so great. Thanks

 

[imloggedin]

I finished putting together my Rev D board and calibrated it all with a signal generator, but the weirdest thing is happening. As soon as I plug in an output XLR, I get alot of noise and the VU meter pegs out. It doesnt matter if the cable is plugged in on the other end or not, or if the input is plugged in or not. Just a chassis with power and as soon as I plug in the output XLR this happens. I haven't looked through all 133 pages of this thread, but does anyone have any idea why this would happen?

 

[imloggedin]

FYI. It was because I didn't ground the board to the chassis. I didn't I would need to. Very odd. Everything works after I did that.

 

[ncoak]

just wrapped up my rev D - all hairball, but rotary. audio (attack knob) & meter bypass, slam mode. calibrated well, and sounds great. thanks much to mnats & mike at hairball for doing such a thorough job with the documentation & component sourcing.

inside...tried to be neat but it's against my nature

outside

slam!

 

[lendavid]

Hi All,
I'm new to this forum. I just finished a rev D from hairball. Great build!
I've got it calibrated and the compression works. The only thing I find is that the attack knob has no audible effect on the signal.
I also do not see a difference in the VU GR readout.
Any thoughts?
Thanks,

Len

 

[Echo North]

Hi All,
I'm new to this forum. I just finished a rev D from hairball. Great build!
I've got it calibrated and the compression works. The only thing I find is that the attack knob has no audible effect on the signal.
I also do not see a difference in the VU GR readout.
Any thoughts?
Thanks,

Len

The attack control is pretty fast.  It's not visually noticeable like the release.  You have to listen on a source like a snare hit or something to catch it.

Definitely subtle.

 

[Majestic12]

.

 

[sr1200]

I kind feel my units have quite noticeable attack time (more apparent with staccato things like snare or kick) but also with bass and vocals as well.  U sure everything is alright under the hood?

 

[Soundmugician]

Mine ( dual revD ) seems to be less noticable on signals with smaller or less transients, but like Mr. Echo North says it's pretty subtle, if you turn the attack knob up on a pretty dynamic snare with decent compression it should get a little "dull" especially on the transients, opposed to being down where it lets transients through before compression begins.

 

[john12ax7]

I'm 90% percent done with the Hairball 76 rev D. have a few questions/issues:

1) Does anyone know of a replacement part number for the Hairball meter replacement lamp? It's 8037 on the Hairball site but was hoping to just get one at Radio Shack if possible, as it seems a bit silly to mail order a $1 part, plus would like to use it asap.

2) The +4 and +8 meters work but the GR setting is not working. Any main culprits to look for? I didn't do the board wiring so am hoping someone knows of a common error.

3) My unit seems to have a lot of gain, way more than my UA 1176, is this typical? Also I notice a very large range for the release knob, but as a previous poster mentioned the attack seems to do very little. On drums I hear a slight difference, but it's very very subtle. My UA 1176 has much more range.

 

[john12ax7]

Ok fixed the GR meter. Turned out to be a bad connection on the meter board. Just a note to others, if you need to re-work a board be careful with the soldering iron temperature, the pcb pads can lift causing bad connections.

So anyone know where to buy the lamps?

 

[Bandit]

Just  couple of quick questions if anyone can help. My Rev D is fully working and sounds awesome but I'm unsure about the following:

R44 never seemed to do anything when i adjusted it but all other calibration steps worked fine and meter seems to be reading correctly. Does it matter that I never used it?

If I get compression levels as desired and all levels correct is there a way to bypass to check out put level of compressed vs uncompressed signal? If I try this by turning attack knob to off position the output level is way too high due to the levels being set for the compression. Is there something wrong here?

Any help would be amazing and I apologize in advance if this has been covered somewhere already.

 

[john12ax7]

Bandit, putting the attack in off position simply turns off the compression, the circuit and amplifiers are still in the circuit. There is no way to truly bypass the unit unless you wire in a switch or patch/unpatch from the patchbay. I will double check mine, but I don't remember having a really drastic volume change when going to off (although some volume change is to be expected).

 

[PeterL]

Hey all. I'm new to this forum and I try to search before I ask a question, but I can not find a solution.

Recently finished building two Hairball kits with Mnats Rev D PCBs and they both sound very different from each other. The first one was built about a month ago and I loved it so much I ordered a second. When I finished the second one and calibrated them both together, I then sent stereo room mics to each for a listen. Immediately noticeable was that the second (new) build was brighter and squashed a bit harder with multiple ratio buttons pushed in, compared to the once I built a couple weeks ago, with the same control settings.

This new build is also quite a bit louder when I try to match the Input and Output controls for each. Something else, when I turn the Attack knob the the fastest position, I get loud "pops" on the front of kicks or snares when they are hit. Backing off the Attack makes it not pop, but I would like to fix this.

If anybody who recognizes these issues and knows how to fix them could help me out I would be very grateful. I have tried to search this forum and Google for an answer but I could not find the information.

These are the voltages from the two points on the PCB seem to be within an acceptable range.

Unit 1
R87  29.87 
CR6  -9.64

Unit 2
R87  29.78
CR6  -9.63

 

[sr1200]

my guess for the difference between the two is the transistors used were quite different (as in not matched) if you're trying to build a stereo unit, i would think that the transistors would have to be closely matched between the two units (as well as all the other parts... resistors etc)

 

[Echo North]

On the MNATS site there is a REV D schematic with typical voltages added.  I would check them all in both units.

Mike

 

[PeterL]

Thank you sr1200 and Mike for your quick replies. And I forgot to say in my last post thank you Mike and Mnats for making all of these parts and information so available. It has been a blast putting these two compressors together!

sr1200, I think you are right, that is something I did not take in to account and I will try matched transistors.

Mike, I'm not sure what to look for, but so far the voltages are quite close. A little bit of under or over is okay, it's something very different from mnat's voltages that I am looking for? Here is an example of some of my voltages so far:

Unit 2

R42 14.21 and 3.428
Q10 15.8
Q5 2.731 and 24.77 and 3.257
Q14 11.23
Q3 1.16 and 11.82


Unit 1

R42 14.24 and 3.429
Q10 16.00
Q5 24.93 and 2.728 and 3.265
Q14 12.01
Q3 1.16 and 12.01

I'm hoping to find whatever is causing the loud popping when fast transients come through the compressor. When I back off on the attack knob the popping stops.

 

[mnats]

sr1200, I think you are right, that is something I did not take in to account and I will try matched transistors.

I doubt that unmatched transistors would account for the things you describe. But if you are planning to link two units to use in stereo it's a good idea to match the gain reduction FETs.

Mike, I'm not sure what to look for, but so far the voltages are quite close.

On the MNATS site there is a REV D schematic with typical voltages added.  I would check them all in both units.

Emphasis added to Mike's reply above.

Unit 2

R42 14.21 and 3.428
Q10 15.8
Q5 2.731 and 24.77 and 3.257
Q14 11.23
Q3 1.16 and 11.82


Unit 1

R42 14.24 and 3.429
Q10 16.00
Q5 24.93 and 2.728 and 3.265
Q14 12.01
Q3 1.16 and 12.01

Note that there are three voltages for each transistor while you have given only one for Q14:

The collector of Q3 is connected to the base of Q14 so these voltages should be identical. Check each one however because this can show up an immediate issue.

You have eight bipolar transistors left to go and a few missing figures from the above. The FETs can vary quite a bit so typical voltages aren't given but post them anyway - it can help trace the problem.

Also, could you clarify which unit has the popping problem? The louder one or the softer one?