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

[Hakonbk]

Hello Everyone.
First of all, thank you hairball for making such great sounding preamps I just finished my second Lola build, and and are experiencing the following two problems:

One of the DOAs doesn’t work(DIY-990). I hear a loud click when pressing the phase and line buttons, and the sound is crackling and low, with no ability to adjust gain. I checked for possible soldering bridges up against a functioning DOA and couldn’t find anyone. Also double checked and all the components are in its right place with right orientation.

There is also no sound from the main 500 unit. I followed the troubleshooting guide with a multimeter and I can’t get a voltage reading from TP3/TP4. Does that mean that the relays K1 and K2 are malfunctioning?

Any tips on how to proceed/troubleshoot the unit from here?

All the best!
Håkon

 

[Toobme]

Is the D.I. working? If so, it’s Likely the relays. Reflow those joints and try again. Also make certain your DOA sockets are making good contact.
I had this on my Lola and it was that my first solder didn’t quite penetrate on all pins of the relay. Hopefully you’ve got a test jig to help with dialing it all in. I use the one from Capi and it’s been great. Classic Audio Products, Inc.

 

[Bthornewill]

Hi everyone! Just finished building my first Lola pre. The pre is working correctly. Sounds great! The input signal on both the DI and Mic input is sending through just fine but the metering isn't registering unless the input signal is insanely hot. The LEDs will light all the way into the red but only if both knobs are at full and I am howling into the mic. The is the case for both VU and PPM.

Any idea where the issue might be? Or how best to troubleshoot?

Thanks so much!

B

 

[pheinberg]

Hi, folks. My Lola with 2 DIY 990s isn't passing the smoke test. I'm pretty convinced one of the 990s is wrong, but cannot find a circuit diagram or test point expectations anywhere. Any guidance would be appreciated!

 

[wsscott]

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.

Did you ever resolve the LED issue? I built my Lola and its working fine but the Middle Yellow LED doesn't respond. All of the others are fine. I re-soldered the pins, and also have continuity between the IC pin for that LED and the pin of the LED. So there's a good connection. The 47K ohm resistors are all fine. Any ideas? Thanks.

 

[YoDudeRock]

Did you ever resolve the LED issue? I built my Lola and its working fine but the Middle Yellow LED doesn't respond. All of the others are fine. I re-soldered the pins, and also have continuity between the IC pin for that LED and the pin of the LED. So there's a good connection. The 47K ohm resistors are all fine. Any ideas? Thanks.

Did you check the LED's themselves? You could be able to run a 3V battery (like a watch battery or 2032) with electrodes to the positive and negative sides of the bulbs to see if they actually work. If not replace them. They are cheap on amazon.

 

[wsscott]

I only have 1 bad LED and Hairball is sending me a new one. My DMM has a diode circuit that might illuminate the LED. It puts out a little over 1.5 VDC, and I think a yellow LED needs about 2v. I'm concerned about using a 3V battery without a resistor.

 

[YoDudeRock]

You're right about the voltage, mine say 1.8v-2.2v. I tried applying 1.5v and it wasn't enough. 3v DC for a few seconds shouldn't do any damage, you could use a half dead 2032 or a resistor would work. It's probably the LED and just swapping out the LED will probably solve the problem.
How do you like the LOLA?? I have one, I love it. Sounds great, lots of headroom and the 1/4 instrument input sounds fantastic on bass guitar or clean electric guitar.

 

[wsscott]

I tested the new LED with a 3.0v battery and it lights. I replaced the part in the Lola LED board and it now works. The old LED did not light up when removed from the circuit and connected to the battery, so either it was a bad part or it was blown when I installed the IC board in reverse. Anyway, its working fine now. I built this board for my buddy who is a drummer and has a recording studio. So this is for him. He was able to listen/test the Lola in the interim and really likes it. He says its got a really clean tone. My ears are too old to tell the difference, but it was fun to build. The main PCB is pretty simple, but the 990 OpAmp kit is pretty tedious. But, just be careful and don't have any sloppy solder joints grounding each other out. I think all of the boards, not just the LED board, would be better designed if you installed sockets to the boards, rather than soldering the IC's directly to the board. They only cost pennies, and it sure makes it easier to fix one of the IC's if it blows or you install it in reverse like I did. If I ever do another one, I'll get some sockets and put them in. I'm sure there's enough room. Thanks for everyone's help. Best.

 

[zerstortezelle]

So ...

Building a Lola pre with DIY990 DOAs. Had a significant smoke out on the first go around with r36 and r37. Upon inspection thought I might have had a resistor on the DOA short on the screw for clamp on transistor.

Ordered single replacement DIY990 and built (extra careful) but still no luck. All relays click and produce output to my DAW when cycled. I can also hear the noise floor come up when I crank the pre.

Popped my two ba512s (from my pair of hairball copper I'd previously built) in to see if it was the DOAs but again and no luck. I started going through the troubleshooting document and found that test point 5 in the signal flow is reading off. Intermittent .05vac on both points with or without the DOAs. Grey is kind of hard to get a reading overall. Reflowed here and still no luck.

Thoughts? Bad input transformer?

Thanks!

 

[TillM]

My first recommend would be, to check all components.
Your transformers have nothing to do with the burnt resistors.
When you have noisefloor, check the soldering at the Grayhill.
But as I said, definitely check all components carefully.

With your old 990 DOAs: Check if 181/171 are changed and in the right direction. Check all diodes and all transistors and condenser.

 

[zerstortezelle]

My first recommend would be, to check all components.
Your transformers have nothing to do with the burnt resistors.
When you have noisefloor, check the soldering at the Grayhill.
But as I said, definitely check all components carefully.

With your old 990 DOAs: Check if 181/171 are changed and in the right direction. Check all diodes and all transistors and condenser.

Well, I replaced r36 and r37. the mic pre tried with other DOAs and did not smoke. I'm leaning towards transformer issue as specified in the troubleshooting specified by Hairball.

Operating noise floor seems like a typical output operating noise with the pre at full. Feeling like the issue is somewhere in the input section. Hairball suggesting reflowing the mic input transformer points again. Will try this and report back.

Anyone other thoughts?

 

[zerstortezelle]

After some troubleshooting and general metering and digging, the transformer was faulty and had a short to ground. Hairball sent a replacement super fast and all is well with pre now. Sounds great too. Great company and great experience!

 

[mrmike186]

Finished my Lola a couple weeks ago and everything working great so far. Haven't finished the DIY 990 op amps but I had a couple SL red dots and a couple gar918s to try. The gar 918s were very noisy and quickly got very hot so I shut them down right away. The SL red dots have worked perfectly with no heating up for the last couple weeks so I've been enjoying the Lola very much.

A few questions for the group are about replacement op amps. Any reason why gar918s would not work? Is it okay to use two different op amps? I finished my first DIY 990 but it immediately smoked when paired with the red dot. Never had a DIY preamp not work but I've screwed up more than one opamp lol.

Lastly, has there been any problems with the thin wire that holds the 20uH inductors to the 990 pcb? Seems like a dab of adhesive could help take the strain off the wire.

UPDATE: With a little maintenance the Gar918's work just fine and the next two DIY 990's are also working fabulous. It does say to use identical op amps so that's what I'll do from now on. Time to get started on the second Lola and put them on drum overheads as planned. One more DIY 990 to build and hopefully resurrect the first one I screwed up so I can have 2 identical Lolas.

 

[joellegros]

Messed up installing the 100 pF caps (C9 & C7). When I desoldered them, the component fell apart. The leg came off. I've emailed hairball to buy some more, but I have yet to hear back from them. Would these work? They need to sit under the opamp on the main board, so they need to be small enough.

https://www.amazon.com/CGjiogujio-V...eywords=100pf+capacitor&qid=1673301444&sr=8-5

 

[scott2000]

Would these work? They need to sit under the opamp on the main board, so they need to be small enough.

10kv seems awful excessive .... 8mm lead spacing is pretty large for these as well
I'm not familiar with the build but have some (4) Kemet Goldmax K2j.... 200v 100pf tiny guys if you want them.... Shipping probably faster with Amazon than snail mail though....

I think they're probably these

https://www.mouser.com/ProductDetai...=sGAEpiMZZMs7ZEmUmaUL03n7AM1G73N1NS8Yh7/WtO0=

 

[joellegros]

10kv seems awful excessive .... 8mm lead spacing is pretty large for these as well
I'm not familiar with the build but have some (4) Kemet Goldmax K2j.... 200v 100pf tiny guys if you want them.... Shipping probably faster with Amazon than snail mail though....

I think they're probably these

https://www.mouser.com/ProductDetai...=sGAEpiMZZMs7ZEmUmaUL03n7AM1G73N1NS8Yh7/WtO0=

awesome thank you

 

[scott2000]

No problem. I'm not saying the mouser link is what you need but, that's what I have.... they would probably work perfect if I had to guess....
Pm me if you would like the ones I have here.... I can throw them in an envelope and in the mail or you could pay for priority if you were in a rush...May save a couple of days...idk... you never know with the post office....

 

[joellegros]

No problem. I'm not saying the mouser link is what you need but, that's what I have.... they would probably work perfect if I had to guess....
Pm me if you would like the ones I have here.... I can throw them in an envelope and in the mail or you could pay for priority if you were in a rush...May save a couple of days...idk... you never know with the post office....

Super nice of you. Actually, Mike got back to me and is mailing some, so it looks like I'm taken care of. Nice seeing other Florida folks on this forum!

 

[scott2000]

Super nice of you. Actually, Mike got back to me and is mailing some, so it looks like I'm taken care of. Nice seeing other Florida folks on this forum!

Awesome...No problem....
Yeah there are several FL on here that I know of. I'm pretty dug in and rooted at least as far back as Billy Powell afaik.
Good luck with your project....