[BUILD] Hairball Audio - Elements

[Echo North]

now that my bad copper is a great copper the other copper has a bit of humming I noticed

It's not too bad, I can lower the input and up the output to compensate but since my other copper is absolutely noiseless I would like to try to get this one there as well.

I checked the slot and cabling and they are fine so it's definitely the copper itself.
The wires on the transformers are as short as it can be and the soldering is clean.
Other than that are there any usual suspects I can check on?

thanks

Is it closer to the power supply? Does the hum follow the unit? Try putting it in the slot furthest from the supply.

 

[mrtomcat]

I moved it to the middle slot and the hum was the same the other slots are full

 

[Echo North]

I moved it to the middle slot and the hum was the same the other slots are full

You could send it in, but I would suspect something localized to your set up.

Are the green wires on the input tx soldered well? Do you have the full enclosure on?

Mike

 

[tctonn]

Hi Mike,

I finished the build on my Gold unit and it seems to be working well. It has decent level with both the DI and main inputs and all controls are working smoothly. But it has a persistent low level buzz that goes up and down with the gain. It's quiet but it is there consistently. The noise becomes especially pronounced with the last step of the gain knob.

The self noise on the Gold is very low other wise and none of my other units in the rack are having any issues.

Any ideas where I should start poking?

Thanks!

Travis

 

[Echo North]

Hi Mike,

I finished the build on my Gold unit and it seems to be working well. It has decent level with both the DI and main inputs and all controls are working smoothly. But it has a persistent low level buzz that goes up and down with the gain. It's quiet but it is there consistently. The noise becomes especially pronounced with the last step of the gain knob.

The self noise on the Gold is very low other wise and none of my other units in the rack are having any issues.

Any ideas where I should start poking?

Thanks!

Travis

I would suspect something external to start. What is your rack brand? Where is the power supply in relation to the rack space your pre is in?  Does moving it to a space further from the supply help?

Mike

 

[radtunez]

Hey Mike,

Finished up my build on my Copper, and alas, no signal The only indication that *something* may be working is that the LED light comes up on my 48V. Otherwise, nothing. I checked all of my joints, and they look pretty good to me. I attached a photo. I also cross referenced my component placement with other successful copper build photos, and it looks like I got that all right. And I checked all resistors were working before I put em in. Here are a couple of points in my build I was wondering if you think may be the culprit, otherwise I'd love some advice on where to troubleshoot:

- I accidentally soldered the fuses on below the indent in the lead - would the resulting elongated lead cause issues there?
- I had poor flow on my blue gain capacitors and spent a while (a lot of heat) rectifying those joints, but I read in another post that it'd be pretty hard to fry them, yeah?

Thanks,

Ryan

http://i1167.photobucket.com/albums/q622/twicetheking/IMG_8378_zps3myyl3yd.jpg
http://i1167.photobucket.com/albums/q622/twicetheking/IMG_8376_zpsc17smkzf.jpg
http://i1167.photobucket.com/albums/q622/twicetheking/IMG_8375_zps5nezgj4w.jpg

 

[Lachlan C.]

Ok, so I still having haven't found the cause of the noise. ..

1)I've swapped opamps (with known working one) and noise is still present on higher gain settings.

2)When I pull the opamp noise goes (makes sense).

3) Double checked gain resistors on input attenuator PCB.

4) Switching pad or phase switches produces large spike is output - DC leaking somewhere?

5) I tested 470uF Radial and 10uf Coupling Tants (and tried replacing) - noise is still present.

Not sure where else to look. 

Also do you have a link to a schematic - the one of the first page is not working.

Many thanks!

Lach

I'd be suspicious of the output section. Check your Q600/601 placement, orientation and the components around it as well as the load components.

Hi Mike, put it on the back burner but am still having noise issues. Here is my findings ....

Swapped input transformer - no change, noise still present

Replaced output BJTs - no change, noise still present

Installed 68pf cap into C502 space - this reduced noise but did not eliminate it.

Any thoughts?

Just to be clear, I have tried the other noise free unit in the same lunchbox slot and it worked perfectly.

Thanks for your help, I appreciate it!

Lach

 

[Echo North]

Ok, so I still having haven't found the cause of the noise. ..

1)I've swapped opamps (with known working one) and noise is still present on higher gain settings.

2)When I pull the opamp noise goes (makes sense).

3) Double checked gain resistors on input attenuator PCB.

4) Switching pad or phase switches produces large spike is output - DC leaking somewhere?

5) I tested 470uF Radial and 10uf Coupling Tants (and tried replacing) - noise is still present.

Not sure where else to look. 

Also do you have a link to a schematic - the one of the first page is not working.

Many thanks!

Lach

I'd be suspicious of the output section. Check your Q600/601 placement, orientation and the components around it as well as the load components.

Hi Mike, put it on the back burner but am still having noise issues. Here is my findings ....

Swapped input transformer - no change, noise still present

Replaced output BJTs - no change, noise still present

Installed 68pf cap into C502 space - this reduced noise but did not eliminate it.

Any thoughts?

Just to be clear, I have tried the other noise free unit in the same lunchbox slot and it worked perfectly.

Thanks for your help, I appreciate it!

Lach

If you can, try swapping op-amps with your friend. See if the noise follows the op-amps.

Mike

 

[Echo North]

Hey Mike,

Finished up my build on my Copper, and alas, no signal The only indication that *something* may be working is that the LED light comes up on my 48V. Otherwise, nothing. I checked all of my joints, and they look pretty good to me. I attached a photo. I also cross referenced my component placement with other successful copper build photos, and it looks like I got that all right. And I checked all resistors were working before I put em in. Here are a couple of points in my build I was wondering if you think may be the culprit, otherwise I'd love some advice on where to troubleshoot:

- I accidentally soldered the fuses on below the indent in the lead - would the resulting elongated lead cause issues there?
- I had poor flow on my blue gain capacitors and spent a while (a lot of heat) rectifying those joints, but I read in another post that it'd be pretty hard to fry them, yeah?

Thanks,

Ryan

http://i1167.photobucket.com/albums/q622/twicetheking/IMG_8378_zps3myyl3yd.jpg
http://i1167.photobucket.com/albums/q622/twicetheking/IMG_8376_zpsc17smkzf.jpg
http://i1167.photobucket.com/albums/q622/twicetheking/IMG_8375_zps5nezgj4w.jpg

Hard to say.

The soldering is the first thing the pops out to me. It's no bad, but not great either.  Reflow and weird joints and trim your leads. Does the DI work?

Repair info if that interests you:
http://www.hairballaudio.com/build-support-services

Mike

 

[Lachlan C.]

[/quote]

If you can, try swapping op-amps with your friend. See if the noise follows the op-amps.

Mike
[/quote]

Thanks for replying, Mike. I did try swapping opamps between units and the noise does not follow to other unit, I.e. opamp is not causing issues. It's a strange fault!

Lach

 

[analogexplosions]

I'm having the strangest issue with a Copper right now.  This will be the second of these I've built, first one worked perfect the first time.

This one, not so much.  I get signal through the DI, and with a dynamic/Non-48v mic and everything works as expected.  When 48v is engaged, the LED lights, but no sound comes through the mic.  The strangest part is that the Copper itself becomes microphonic and if i tap anywhere on it, I get signal of my tapping.  ( like, I can audibly hear my tapping on the pre coming through the speakers)

What idiotic thing could I have overlooked?

 

[ln76d]

Somwhere you lose ground connection

 

[achase4u]

Ruh Roh!  Where should I look here?  There is a relay to switch between the mic and DI automatically, correct?  Perhaps somehow it is stuck in DI mode?  Thoughts on where to check?

On the plus side.  The DI sound uhhhhhhhhhmazing!

 

[achase4u]

Ok - so I noticed the issue.  At R200, I actually have nothing installed, and I have a left over 100k resistor.  It has the same color code as the 100k resistor at r502 BIAS.  Since there is only one 100k resistor needed in this build, it seems I got two 100ks instead of one 100k and another 1k?

I measured every resistor before I installed it.  So this leads me to believe the reason I didn't install anything at R200 is because I didn't have one, and I have this left over 100k.  The only scenario I can imagine where I used the 1k somewhere I shouldnt, would be at R502 bias, because that would have left over the 100k resistor.

I realize how silly it is to load up a build before all components are placed and you've got an extra left over - but it just totally slipped my mind I guess.

 

[darkus]

Im having similar issue. DI and dynamic works, but no phantom.

Ive had an extra 100k in all of my 4 copper kits btw.

 

[blackartmixing]

Hi have built two Copper pres and i have the same problem with both.  I get DI but no mic input.  i know that has been mentioned in the thread so far but i've checked and both have the relay soldered in correctly.  i've tried to add more solder to the joints and all solder points appear to be good but still i'm not getting any switching. 

Can anyone advise how i can troubleshoot this further please??

 

[Echo North]

Hi have built two Copper pres and i have the same problem with both.  I get DI but no mic input.  i know that has been mentioned in the thread so far but i've checked and both have the relay soldered in correctly.  i've tried to add more solder to the joints and all solder points appear to be good but still i'm not getting any switching. 

Can anyone advise how i can troubleshoot this further please??

Possibly another bad component in the relay circuit.  When you power the unit on, with nothing in the DI jack, you should hear a small click in the relay switching it to mic. 

 

[blackartmixing]

Hi have built two Copper pres and i have the same problem with both.  I get DI but no mic input.  i know that has been mentioned in the thread so far but i've checked and both have the relay soldered in correctly.  i've tried to add more solder to the joints and all solder points appear to be good but still i'm not getting any switching. 

Can anyone advise how i can troubleshoot this further please??

Possibly another bad component in the relay circuit.  When you power the unit on, with nothing in the DI jack, you should hear a small click in the relay switching it to mic.

Actually the mic input works when i reset the power to the chassis then i plug in a DI and that works but when i remove the DI it doesn't switch back to the mic input 

 

[Echo North]

Hi have built two Copper pres and i have the same problem with both.  I get DI but no mic input.  i know that has been mentioned in the thread so far but i've checked and both have the relay soldered in correctly.  i've tried to add more solder to the joints and all solder points appear to be good but still i'm not getting any switching. 

Can anyone advise how i can troubleshoot this further please??

Possibly another bad component in the relay circuit.  When you power the unit on, with nothing in the DI jack, you should hear a small click in the relay switching it to mic.

Actually the mic input works when i reset the power to the chassis then i plug in a DI and that works but when i remove the DI it doesn't switch back to the mic input 

That's weird. Make sure the edge card gold contacts are super clean.  Check all the components and values in the relay circuit.

 

[blackartmixing]

Hi have built two Copper pres and i have the same problem with both.  I get DI but no mic input.  i know that has been mentioned in the thread so far but i've checked and both have the relay soldered in correctly.  i've tried to add more solder to the joints and all solder points appear to be good but still i'm not getting any switching. 

Can anyone advise how i can troubleshoot this further please??

Possibly another bad component in the relay circuit.  When you power the unit on, with nothing in the DI jack, you should hear a small click in the relay switching it to mic.

Actually the mic input works when i reset the power to the chassis then i plug in a DI and that works but when i remove the DI it doesn't switch back to the mic input 

That's weird. Make sure the edge card gold contacts are super clean.  Check all the components and values in the relay circuit.

Did a bit more reflow work and all looks to be good now.  thanks for you time