[BUILD] Hairball Audio "Lola" Mic Pre - On Sale Now

[Echo North]

Ah got you.  I've never seen the ground to rail diodes on a 500 module but I'll look into it for the next round.  Always room for better design!

It is strange indeed.  There are a few hundred Lola's out there and this is the first time I've come across this.  Build error or component failure is a possibility.  You'd have to isolate the problem to one unit.

Keep me posted and let me know if you need anymore info.

Thanks!

Mike

 

[Echo North]

Also, if the opamps are DIY it is somewhat common for builders to have an error which will cause a short on the opamp.  The Lola has 4 10R (1 for each rail and each opamp) resistors on the main PCB that should burn out in this case.  I wonder if the supply fuse is tripping before the 10R is having a chance to fail?

Just a theory.

Mike

 

[qtuner]

Just got done building my lola, but there is an issue with the DI.  the Di only works when the the di button is not engaged and a mic cable is plugged in.  Bad relay?

 

[Echo North]

Just got done building my lola, but there is an issue with the DI.  the Di only works when the the di button is not engaged and a mic cable is plugged in.  Bad relay?

I think you've got the functionality backwards.

The switch you're referring to is a line switch.  It's not associated with the DI jack, they are separate and can't be operated at the same time which is why you get no signal with the DI in and the switch on.

The line switch is for "re-amping" line level.  You can only use the mic input (XLRs in you 500 rack) in line mode.  So if you want to say use the Lola for make up gain after a compressor, you'd use line level.

The DI jack is for hiZ instruments.  You don't turn it on.  By pulging a 1/4" instrument jack into it you break a ground connection that trips the Lola into DI mode.

Sounds like yours is working correctly.

Let me know if you have any questions,

Mike

 

[qtuner]

I did get it backwards.  It was working fine  :-[

 

[Trench Recordings]

Two Lola up and running. Good kit and instructions. Thanks Mike

 

[Jbeckbass]

Just finished building 2 Lola's.  They sound fantastic, but I am having an issue with the meters.  Both read very high, when I am showing 0 on Lola in ppm, my lynx aurora-pt hd only shows about -10. Switched to vu the difference is about 6db between Lola meter and pt/lynx.  Both preamps doing exact same thing.  Any ideas?  Thanks in advance!

 

[Echo North]

Just finished building 2 Lola's.  They sound fantastic, but I am having an issue with the meters.  Both read very high, when I am showing 0 on Lola in ppm, my lynx aurora-pt hd only shows about -10. Switched to vu the difference is about 6db between Lola meter and pt/lynx.  Both preamps doing exact same thing.  Any ideas?  Thanks in advance!

The Lola is calibrated so that +4dBu = 0dB on the meter.

Your Lynx is probably calibrated to dBFS.  Which is something different entirely.

My guess is that it's working correctly and that there is just a dB type mismatch.  -10dBFS could reasonable be 0dBu on the Lola in PPM.  There is no way to mathematically convert dBFS to dBu because dBFS is converter dependent. 

Little more reading here:
http://www.hairballaudio.com/blog/d_assembly/revd/calibration/

If you can measure across pin 2 and 3 of the Lola output XLR, at 0dB in VU mode you should see roughly 1.2VAC and in PPM 0.775VAC at 0db.

Mike

 

[leeunfried]

Hey Mike,

Got my Lola Kit in and the build is going great!

I ordered my kit with the BA512 op-amps.
Before I send power to the unit I want to double check on one thing:
The attached photo is the excerpt from the manual that is in question.

Do I need to put an additional cap or resistor on the PCB if I am using the BA 512 op-amps?

Thanks!

 

[Echo North]

Hey Mike,

Got my Lola Kit in and the build is going great!

I ordered my kit with the BA512 op-amps.
Before I send power to the unit I want to double check on one thing:
The attached photo is the excerpt from the manual that is in question.

Do I need to put an additional cap or resistor on the PCB if I am using the BA 512 op-amps?

Thanks!

For the BA512 they should be left empty, just like the 990.

 

[dduwa]

Finished my second LOLA a few weeks back and it seems to be working great, except for one thing. When the meter is in PPM mode, it decays very slowly. I've compared the meter's behavior to my other LOLA by plugging identical mics in each preamp, with the same gain settings and clapping my hands. My first LOLA has a very fast decay - almost immediate, but the newest one is quite slow by comparison.
I've double and triple checked the component placement on both meter boards, but can't figure it out. Any thoughts?

Thanks!

 

[okgb]

If you're sure the values are correct , check for solder overflow or bridges on the meter pcb
the solder mask saves allot of sins but it's still possible

 

[dduwa]

I'm still trying to get this meter problem fixed. At the advice of okgb, I went back and looked for solder bridges. While I was at it, I retouched every solder connection that I could get to with a hot iron, and in some cases even added a bit more solder to some joints that looked a bit sketchy. I couldn't find any solder bridges, and it's still doing the same thing. I checked the placement of every component to the working meter board I have and it all looks legit. At one point, I thought I had a wrong resistor in R112, so I unsoldered it and checked it with the DMM, but it was correct. I also swapped meter boards on my two Lola's to make sure the problem wasn't with the Lola, and sure enough, it still didn't work.

I'm at a total loss, so I'm hoping someone can help. I took several pics of both sides of the board and posted them on my site. If anyone has the inclination to take a look and provide feedback, I would be very grateful. Thanks!

Front 1 http://dustinduwa.net/?attachment_id=770
Front 2 http://dustinduwa.net/?attachment_id=771
Front 3 http://dustinduwa.net/?attachment_id=772
Front 4 http://dustinduwa.net/?attachment_id=773
Back 1 http://dustinduwa.net/?attachment_id=766
Back 2 http://dustinduwa.net/?attachment_id=767
Back 3 http://dustinduwa.net/?attachment_id=768
Back 4 http://dustinduwa.net/?attachment_id=769

 

[Echo North]

Double check around R110 and C106.  Is C106 oriented correctly?

Also confirm C106 is a 2.2uF and we didn't send you something else.

Also if you can clean the flux off the bottom.  You'd be surprised what flux can do in a circuit.

 

[okgb]

On one of mine I found too much solder flowed to the other side of the board side where the l.e.d.'s were mounted
and shorted one of the led's . I had to pull it out and re-install and it was fine , maybe not your problem but that is
why I suggested checking [ you can't see underneath ] good luck. It still sounds like a great preamp without the meters
but they can be handy .

 

[brent]

Hey guys,

My first build is melting the 10 ohm, R31 and R32 resistors. My first thought is I have a problem with one of the DIY 990's pulling too much current in DOA socket 1.  R36/R37 for socket 2 look to be still in tact.  I've visually gone over each component compared to the other DOA I built, and everything appears to be in the right place.  Q8 and Q9 have the correct transistors and there are no shorts from diodes to the clamp.  Before I swap the suspect DOA into socket 2 to see if it melts R36/R37, is there anything else I should test/verify?  Just for clarification I'm using 16v rails in an API 500 series rack.

-B

 

[Echo North]

Hey guys,

My first build is melting the 10 ohm, R31 and R32 resistors. My first thought is I have a problem with one of the DIY 990's pulling too much current in DOA socket 1.  R36/R37 for socket 2 look to be still in tact.  I've visually gone over each component compared to the other DOA I built, and everything appears to be in the right place.  Q8 and Q9 have the correct transistors and there are no shorts from diodes to the clamp.  Before I swap the suspect DOA into socket 2 to see if it melts R36/R37, is there anything else I should test/verify?  Just for clarification I'm using 16v rails in an API 500 series rack.

-B

Ya that's what happening.  If you do the switch you'll most likely fry the others.

Troubleshooting the op-amps are though because the space is so tight.  Typically this is a MJE171/MJE181 mix up.  If you're sure they are right you can look for shorts and maybe you have a bad transistor.  I can send you new parts if needed.

 

[brent]

Ya that's what happening.  If you do the switch you'll most likely fry the others.

Troubleshooting the op-amps are though because the space is so tight.  Typically this is a MJE171/MJE181 mix up.  If you're sure they are right you can look for shorts and maybe you have a bad transistor.  I can send you new parts if needed.

Ya I checked MJE171/MJE181 locations straight away.  Is there a way to test these 2 components with just a FLUKE 287?  I went over the board pretty thorough with a magnifying class and cleaned any residual flux away with 99.99% alcohol.  I'll double check for shorts again tonight with fresh eyes.  Any suggestions on pads to look for continuity between?

I have another kit so I have a few 10R resistors to test with for now if I can track down the culprit.

-B

 

[brent]

Ya that's what happening.  If you do the switch you'll most likely fry the others.

Troubleshooting the op-amps are though because the space is so tight.  Typically this is a MJE171/MJE181 mix up.  If you're sure they are right you can look for shorts and maybe you have a bad transistor.  I can send you new parts if needed.

Ya I checked MJE171/MJE181 locations straight away.  Is there a way to test these 2 components with just a FLUKE 287?  I went over the board pretty thorough with a magnifying class and cleaned any residual flux away with 99.99% alcohol.  I'll double check for shorts again tonight with fresh eyes.  Any suggestions on pads to look for continuity between?

I have another kit so I have a few 10R resistors to test with for now if I can track down the culprit.

-B

Hmm well I found the datasheets and instructions online to test MJE171/MJE181.  It wasn't pretty getting them out of the DOA, but they measure fine, and they're definitely in the right locations.  I can build another DOA tonight and swap out the 10R resistors, but I really want to find the problem before I try another round.  I guess I'll disassemble the DOA part by part and check them....

 

[brent]

Well I'm not sure what's wrong with that op amp.  I couldn't find any shorts on the surface.  I pulled off all the transistors, diodes et al, and everything measures fine.  None the less, I put in a newly built op amp and some fresh 10 ohm resistors and the unit is working fine now.  I guess I'll need to order another DIY 990 and some 10 ohm resistors

-B