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

[stevecrossrock]

Hi all,
I recently did a Lola DIY build, and I've got a few different issues.

-I'm getting clean audio through the preamp and into my DAW, but nothing registers on the Lola meter. When I first turn it on, or hit the phase switch, or hit the phantom power switch, I see a surge on the meter. But nothing registers on the meter when actual audio is coming through.

-When I push the phase switch, I get a very loud nasty pop. Also when turning the top gain knob/switch, as it hits each position, I get nasty pops. The pops get louder as I turn the gain down, and softer as I turn the gain up, counterintuitively.

-The op-amp on top (closest to the edge of the main PCB) has way hotter output transistors than the other op-amp. These are getting hot enough to burn a finger within a second of touching them.

Do any of these issues seem connected, or seem like something that's a common problem/easy fix for an intermediate level solderer/tinkerer? Or should I just jump to sending it in for repair?

 

[mrbobbailey]

Greetings,

I have one of my three recent Lola builds that has issue with the DI signal. The MIC/Line signal may be inconsistent or scratchy when increasing volume, but fine once set, however the DI signal is very distorted and the wave image in my DAW looks heavily weighted to one side of the wave file. 

Is this representing some DC offset issue and where should I begin on troubleshooting? 

- Trouble build has JH990 op amps
- second build is identical, but tested perfect
- third build - I'll need to order a new output transformer when available or attempt to remedy one lead that was cut too short.

Thanks,

Bob

 

[YoDudeRock]

Hey,
    I'm about to build my first two Lolas.  They are both for customers of mine.  One guy asked if I could add a a HPF option at 80Hz or something?
Is that do-able with a simple Resistor-Capacitor combo on a switch without screwing anything up?

Thanks,
Chris

 

[Diamondj421]

I’ve had my pair of Lolas for a few years now but they aren’t much use since I haven’t been recording recently so I decided to use them as an insert on my mix bus. This was about a week ago. This morning there was a familiar scent in the air but I couldn’t put my finger on it so I went about my day. Came back later, hit play on my Pro Tools session and the left channel was drastically quieter than the right. I fiddled around with the cables, restarted my computer, etc and then it clicked (in my head, not the unit). Took out the pre and there was that smell. Where should I start looking to find the bad component?

 

[Diamondj421]

I’ve had my pair of Lolas for a few years now but they aren’t much use since I haven’t been recording recently so I decided to use them as an insert on my mix bus. This was about a week ago. This morning there was a familiar scent in the air but I couldn’t put my finger on it so I went about my day. Came back later, hit play on my Pro Tools session and the left channel was drastically quieter than the right. I fiddled around with the cables, restarted my computer, etc and then it clicked (in my head, not the unit). Took out the pre and there was that smell. Where should I start looking to find the bad component?

Nevermind. Did a little more looking around and saw that R31 was fried.

 

[Diamondj421]

Nevermind. Did a little more looking around and saw that R31 was fried.

Scratch that. R31 AND R32 were fried. What would cause both resistor to go up at the same time?

 

[cskmo]

H, this is my first ever build DIY project, I am encountering one issue, and cannot figure it out why. I tried all the knob and button works fine, no issue on audio in / out, no smoke for now. The VU led meter looks fine, but once I switch to ppm, all the led meter lights are on forever, what may I making it wrong? thanksss

 

[JMan]

I don't know if Mike is watching this thread these days, but I just finished the main board on my first Lola and I have a very minor issue. Everything works (and sounds quite nice!), but my Grayhill switch has a hitch. As I turn it from fully CCW, it increases the signal predictably up until around 12 o'clock. At that point, the next turn creates a very small dip in level, and all subsequent positions remain completely even -- no change up or down from that point. I've looked over my solder joints in that area very carefully and they all look quite good, and I don't see any incorrect resistor values. I looked for shorts, but don't seem to have any. Where should I focus my attention?

To be honest, I could use it as-is and be perfectly happy, but I'd like to get it fully sorted, especially since I don't know how this might complicate things when I add the meter board. I'll also trawl this thread and see if I can find something to point me in the right direction.

 

[udri]

I have the same problem, I have built the LOLA this week, and the Grayhill doesn't affect the gain increase at all... I have also checked, and I can't locate the problem

 

[Toobme]

Just built one and loving it on snare top!
Maybe go over the switch section’s resistors looking for an incorrect value on one if them, if you’re getting that dip.

 

[Toobme]

@cskmo have you tried to reflow that toggle switch? Could be a hidden bridge in there somewhere.

 

[JMan]

I just took a quick pass through the switch section with my meter and it looks like about 5 of the Grayhill pins are shorted together, which definitely would explain my issue. The crazy part is that it is definitely not a short on the solder side of the board, but rather it must be on the top side where the switch is seated (which is nuts because the switch is sitting flush and I don't see how the solder could have any room to create a bridge). Well, now I get to go about the oh-so-enjoyable task of removing, cleaning up, and re-soldering this switch...hurray...anyone have any tips on how to minimize the pain on this?

 

[kato]

* about 5 of the Grayhill pins are shorted together *

I don't mean to nose in to your business, but this seems highly unlikely.

Someone chime in if I'm missing something, but the solder mask on the top should have prevented this. You would have had to flow a ton of solder from the bottom for it to saturate the top pads and flow OVER the solder mask between the pads.

Is that what it looks like has happened from the top? Take a picture if you feel like sharing.

If so, you may be able to soak it up with a solder wick without removing the Grayhill. I find (in such events) that once the solder starts flowing onto the wick, it comes away from the solder mask areas and cleans itself up without much work.

 

[JMan]

I don't mean to nose in to your business, but this seems highly unlikely.

Someone chime in if I'm missing something, but the solder mask on the top should have prevented this. You would have had to flow a ton of solder from the bottom for it to saturate the top pads and flow OVER the solder mask between the pads.

Is that what it looks like has happened from the top? Take a picture if you feel like sharing.

If so, you may be able to soak it up with a solder wick without removing the Grayhill. I find (in such events) that once the solder starts flowing onto the wick, it comes away from the solder mask areas and cleans itself up without much work.

PLEASE, nose in to your heart's content!

I agree that this seems unlikely, but I can't figure out another explanation for what I'm seeing. I mean, I wasn't stingy with the solder, but I also didn't go nuts.

In the first picture below, the five pads in red all have continuity to each other, regardless of the position of the switch. To add some madness to it, the two in yellow ALSO have continuity, BUT (!) for some reason there is no continuity between the left-most yellow pad and any of the other red pads except the one right next to it...and I've scratched my head and checked this more times than I can count.

Tracing through the switch's connections, it is as you might expect. The first several positions only connect the wiper to the appropriate pin, and then, once you hit the first yellow pin, it shorts those two, and then on the next one it shorts all of the remaining five. Obviously this explains the behavior of the gain switch when passing audio, but I still can't work out what's happening on a physical level.

There may be a simple explanation here, but my brain is not coming up with it. I've checked and rechecked -- there are no solder bridges on the solder side of the board, and no obvious ones on the component side, though it could be hiding (see second picture). Also, none of the switch resistor legs are shorting to one another. I'll try hitting it with some solder wick this week and see what happens.

 

[kato]

Oh yeah. No clearance on the top for solder to flow anyway.

Your soldering looks good. This is a real stumper. It seems just as likely that you have a bad Grayhill, which is also super unlikely since I doubt they fail that way.

I would ask Mike at Hairball. He might have some insight.

 

[JMan]

Good call. I will reach out to Mike directly. I was hoping he was watching this thread and would chime in, but he must be focused elsewhere. Anyway, I'll report back with any discoveries!

 

[benkamen]

Hi, Just build my first Lola. All good so far, except two of the yellow LEDs are not lighting up. Tried to resolder them with no luck. Wondering what other components might be the culprit. Thanks.

 

[kato]

I've found LEDs to vary wildly in their ability to light up at the same voltages.

For example, I have two brands of green LED, one with a "luminous intensity" of 19 mcd (according to the datasheet) and another with "luminous intensity" 980 mcd.

So first I'd check the datasheets and see if your greens and yellows are at a similar spec.

 

[JMan]

I’d start with the simplest possibility, that you simply might have installed them backwards

 

[Diamondj421]

Greetings everyone. Back in May, I had one of the op-amps in one of my Lola's go up and it took a few resistors on the main board with it. I replaced the opamp, replaced/rewired the burnt resistors and I had the mic pre up and running again. The DI wasn't working but since I rarely use the DI, I figured I could just come back to that later. Later has come! I'm still struggling financially since COVID hit so I need to sell them to stay afloat. I tested it with my bass and the only way to get signal to pass is by really digging in and playing hard. Even then the sound comes in muffled and dies out pretty quickly. It's almost like a gate. Could someone point me in the direction of what could be causing this? Thanks!