[BUILD] Hairball Audio - Elements

[Echo North]

She works beautifully, DI and all.  The only issue I'm having is the 11th and final gain position tends to drop the signal significantly.  What would have caused that?

The gain switch is a resistor ladder. In the 1st position (lowest gain) all of the resistors in the ladder are activated. In the 11th position (highest gain) none of the resistors are activated. It's a dead short. You have an issue at the 11th node of the switch.

I would check the solder joint on the 11th node of the grayhill. To be sure, you could reflow all of those joints.

Mike

 

[Jussi De Nys]

Hi! I'm finally building my lola's (2). First one is almost done!
I got to the first testing stage and there's no smoke ( hallelujah! ). The phantom button makes a click when pushed and lights up to a nice blue. The same goes for the Line engage button. The phase invert button does not make a clicking sound/feeling and only lights up when being pushed in , it stops being blue when it loses my touch. It seems to me that this button might be broken or something, it doesn't click like the other two. I can only hope that ( since there's no smoke and everything lights up) this might be a simple mistake, I saddly don't have the "know how". It's my first build, maybe I should have started with a simpler one Hope you can help me out! thanks in advance!
Greetings from Belgium,
Jussi.

 

[darkus]

Hey guys,

Im having an issue with my 2 coppers, Im not getting any phantom. Dynamic mics and DI works like should, and the 48v led lits up. I have tried different 500-slots. Any ideas?

 

[Echo North]

Hey guys,

Im having an issue with my 2 coppers, Im not getting any phantom. Dynamic mics and DI works like should, and the 48v led lits up. I have tried different 500-slots. Any ideas?

Really could only be a bad solder joint or misplaced component on something in the +48 box of the PCB or on the switch itself. Try reflowing that stuff.

Mike

 

[EastLeedsWest]

Hey All, I built a copper about a year ago and it came out like a dream. It had been doing daily work until last week. Out of nowhere it stopped working. I unscrewed it from my chassis and before I pulled it out the +48v light came on and it went back to normal. Screwed it back in, light went out. This process will repeat consistently among multiple chassis and I'm completely stumped as to what could be causing it. Has anyone else experienced this? Any ideas on where to start looking for the problem?

 

[Echo North]

Hey All, I built a copper about a year ago and it came out like a dream. It had been doing daily work until last week. Out of nowhere it stopped working. I unscrewed it from my chassis and before I pulled it out the +48v light came on and it went back to normal. Screwed it back in, light went out. This process will repeat consistently among multiple chassis and I'm completely stumped as to what could be causing it. Has anyone else experienced this? Any ideas on where to start looking for the problem?

I would start with scrubbing the edge connector with isopropyl alcohol. Get it good an clean.

Mike

 

[ssttoo]

Just built the second Copper. The first  one works fine, the second is very very quiet. You only hear some faint signal when both gain and output are max'd. Same behavior in DI, same with condenser mic and phantom power (I tried sm57 first). Any pointers where to start looking, anything specific to low volume symptom? I swapped the opamps between the two units, same result: first unit works, second too quiet.

 

[Echo North]

Just built the second Copper. The first  one works fine, the second is very very quiet. You only hear some faint signal when both gain and output are max'd. Same behavior in DI, same with condenser mic and phantom power (I tried sm57 first). Any pointers where to start looking, anything specific to low volume symptom? I swapped the opamps between the two units, same result: first unit works, second too quiet.

Usually a bad joint somewhere in the signal chain. Start by making sure all of the components are correct, then reflow joints looking closely at that larger caps with long leads.

Mike

 

[tonesontail]

Howdy, and thanks for any help provided. I smart searched the forum, and did not find anything on this issue, so...

I am helping a colleague trouble shoot a pair of Gold Elements pres, and they are both exhibiting the same phenomenon.  As the Output pot (VR600) is rotated CCW, the distortion specs go way up and there is an audible hum. I measured over 50% THD+N with a 1khz and .775v on my AP ATS-1 with the pot turned fully CCW. THD+N is less than 1% with the VR600 fully CW. I have checked all of the parts in the 600 section of the build and they are all correct. The NFB components are also correct, and R506 and C506 are Shorts as per the BOM.

Looking at the http://library.hairballaudio.com/images/2015/06/hba-elements-pcb-v1-3_schematic-production.pdf schematic, with the Shorts in place, the 990's Output and NFB loop are DC coupled to ground through VR600 and R600(100R). Could this be generating a massive load on the 990, and causing the distortion? The 990's were provided pre-built.

I know that the Jensen paper shows that the output can be DC coupled directly to the OP TX, but ordinarily has L3/R15 to suppress oscillation, but this has been omitted from this design. I see that C601 blocks DC from reaching the A/B output buffer, so I do not see that section as being the problem.

Could both pre-built opamps be out of spec or bad? Would you suggest putting in a say a 470uf NP cap in at C600 to see if the noise goes away? Is this a know issue?

Thanks

ToT

 

[Echo North]

Howdy, and thanks for any help provided. I smart searched the forum, and did not find anything on this issue, so...

I am helping a colleague trouble shoot a pair of Gold Elements pres, and they are both exhibiting the same phenomenon.  As the Output pot (VR600) is rotated CCW, the distortion specs go way up and there is an audible hum. I measured over 50% THD+N with a 1khz and .775v on my AP ATS-1 with the pot turned fully CCW. THD+N is less than 1% with the VR600 fully CW. I have checked all of the parts in the 600 section of the build and they are all correct. The NFB components are also correct, and R506 and C506 are Shorts as per the BOM.

Looking at the http://library.hairballaudio.com/images/2015/06/hba-elements-pcb-v1-3_schematic-production.pdf schematic, with the Shorts in place, the 990's Output and NFB loop are DC coupled to ground through VR600 and R600(100R). Could this be generating a massive load on the 990, and causing the distortion? The 990's were provided pre-built.

I know that the Jensen paper shows that the output can be DC coupled directly to the OP TX, but ordinarily has L3/R15 to suppress oscillation, but this has been omitted from this design. I see that C601 blocks DC from reaching the A/B output buffer, so I do not see that section as being the problem.

Could both pre-built opamps be out of spec or bad? Would you suggest putting in a say a 470uf NP cap in at C600 to see if the noise goes away? Is this a know issue?

Thanks

ToT

You're measuring with a 0dBu input? That is VERY high for mic pre. Use something -20 dBu to -40dBu. I deal the generator output impedance would be 150Ω. Also, with the output fully CCW your signal may have deteriorated enough to be unusable,  there is not really a realistic recording situation to have the output all the way down. It should be wide open (full CW), then pulled back to add add distortion or "push" the gain structure. Below 12 o'cklock, with the gain up its a fuzz box on purpose.

Op-amps are all tested before ship. Design has been used for 10+ years by both us and Eisen Audio. There is something else going on. Don't over think it. You have your generator set up incorrectly, or something it is misplaced in the build.

Mike.

 

[BrettAudio]

Hello,

I'm just starting my copper build and I've gone through and checked all of my resister values.  After matching everything up I have one oddity: for what should be resister 502 should be a 100K and what I have left is a 82K that is a close but seems a little low.  Thoughts on if that will make a large difference?

 

[Echo North]

Hello,

I'm just starting my copper build and I've gone through and checked all of my resister values.  After matching everything up I have one oddity: for what should be resister 502 should be a 100K and what I have left is a 82K that is a close but seems a little low.  Thoughts on if that will make a large difference?

If the color codes read 100K you're fine.  DMM's have a hard time reading high values because their resistance is in parallel with the resistor you are testing.  If the DMM has a resistance of 1M and the resistor is 100K, you'll see a lower reading.

Mike

 

[BrettAudio]

Hello.

I'm working on the two caps C301 and C302.  It is not clear to me what one is what.  It looks like the smaller package (wider pin/hole spacing) fits the holes for the 100pF cap C301 space and the larger package seems to better fit the C302 space.

My instincts say the larger package would be the 100pF cap and that I would adjust the legs to fit in the holes.

If someone has a good clarification for me on what one is what, I greatly appreciate the help.

Thanks,
Brett

 

[Echo North]

Hello.

I'm working on the two caps C301 and C302.  It is not clear to me what one is what.  It looks like the smaller package (wider pin/hole spacing) fits the holes for the 100pF cap C301 space and the larger package seems to better fit the C302 space.

My instincts say the larger package would be the 100pF cap and that I would adjust the legs to fit in the holes.

If someone has a good clarification for me on what one is what, I greatly appreciate the help.

Thanks,
Brett

The blue caps have values on them. They are just super small and you need to get in the right light.  100pf should have 101 then a letter stamped on it.

Mike

 

[BrettAudio]

The blue caps have values on them. They are just super small and you need to get in the right light.  100pf should have 101 then a letter stamped on it.

Mike

Hello,

Thank you for the information.
I'll take a closer look.

Thanks again,
Brett

 

[BrettAudio]

Hello.

I wanted to report that I completed my first build on my first ever 500 piece of gear.

I fired it up, then I recalled I still need to solder the pins for the in/out gain stage.  Did that, slid it back into the API lunchbox and awesomeness!!!

Mike,
Thank you to you and your team for making great parts.  I'm super stoked to start recording with the copper.

Up next, a Lola mix pre!!!

Thanks,
Brett

 

[darkus]

Really could only be a bad solder joint or misplaced component on something in the +48 box of the PCB or on the switch itself. Try reflowing that stuff.

Mike

Hi! I did reflow the switch and +48 box. No luck there. Ive looked the board for hours and compared it to a fully working preamp and I cant find anything wrong. My solder joints are solid. Dynamic mics work, DI works, +48 led lights up but no phantom.

I noticed that when I have the +48v switch in down position, the other switches (phase and pad) make a really loud popping noise when pushed down. Like, breaking speakers loud. Is this normal?

Pics of my build
https://www.dropbox.com/s/30ooc2omqac67ju/IMG_20170811_105855.jpg?dl=0
https://www.dropbox.com/s/u5evb3m95y6kuuw/IMG_20170811_110223.jpg?dl=0

 

[Echo North]

Hello.

I wanted to report that I completed my first build on my first ever 500 piece of gear.

I fired it up, then I recalled I still need to solder the pins for the in/out gain stage.  Did that, slid it back into the API lunchbox and awesomeness!!!

Mike,
Thank you to you and your team for making great parts.  I'm super stoked to start recording with the copper.

Up next, a Lola mix pre!!!

Thanks,
Brett

Nice!

 

[Echo North]

Hi! I did reflow the switch and +48 box. No luck there. Ive looked the board for hours and compared it to a fully working preamp and I cant find anything wrong. My solder joints are solid. Dynamic mics work, DI works, +48 led lights up but no phantom.

I noticed that when I have the +48v switch in down position, the other switches (phase and pad) make a really loud popping noise when pushed down. Like, breaking speakers loud. Is this normal?

Pics of my build
https://www.dropbox.com/s/30ooc2omqac67ju/IMG_20170811_105855.jpg?dl=0
https://www.dropbox.com/s/u5evb3m95y6kuuw/IMG_20170811_110223.jpg?dl=0

Hmmmmm maybe a bad switch?  Do you know how to test a DPDT switch like that?

Mike

 

[darkus]

Hmmmmm maybe a bad switch?  Do you know how to test a DPDT switch like that?

Mike

Ummmm maybe. Ill desolder it and test the continuity with a dmm after that?