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

[knariman]

So i'm having some trouble. I just built my Lola, and thought I did a great job at first anyway. Made sure I measured all the resistors, keeping track of the unit-kilo-mega factors, and presorted them by taping them to the sorting sheet.

I got the pre-built BA512 DOAs.

My issue is, the unit powers on - buttons light up when pressed, nothing seems burnt, however there is no audio

I've tried the XLR as well as the DI inputs, and nothing. No level on my coverters, and nor do the LED meters on the Lola light up. Any ideas where I should start looking for trouble? Thanks!

 

[knariman]

So I went through the troubleshooting guide. The power checks seemed fine more or less.

Then I moved onto the audio tests. Passed a 1khz Sine Tone from Live’s Operator Synth, adjusted the gain to 3rd position and the trim fully CW. Checked with my DMM and Test Point 1 was giving 0V. Should read 0.2V according to the troubleshooting guide.

It mentions this could be due to an issue with the input Tx? Im quite baffled. What’d should I try from here?

 

[Toobme]

Check all your joints. Reflow. Recheck.

 

[Toobme]

Ya ya, you probably did that already - sorry!
Mine did require a reflow near the trafo, and/or relay for the DI, can’t remember.
But you’ll likely facepalm once you find it.

Hold on, is all I can say, we’ve all been there - and I’ll be there again!
You’ll find it, just go thru every single part, one at a time, really looking at joints and also values.
Sometimes it takes 4 times going over something to see what’s up.

Maybe post a shot of your work, to see if other eyes can spot suttin’

 

[knariman]

Hey Toobeme, thanks for your reply! After reading it, I gave it a long checking session last night.

As expected in true newbie fashion, you were right

Rechecked all my solder joints again, reflowed any that looked even slightly suspect. In fact, one of the Input Tx wire sleeves was kinda melted, so fixed that up. Powered up and it worrkksss, and sounds beautiful!!

Only thing not quite working still is the DI input. Levels are really low (using my guitar with passive pups), and there’s a huge amount of noise. Scanning the forums again, most of these issues seem to be rooted in the Q1-Q3 JFETs. Should I be looking at replacing these? Or is there a way to check them first with my DMM?

Thanks for all the help!

 

[Toobme]

Just check that you’re not using the DI with the Line switch engaged, as that’s for the XLR connection in line mode.
Got a pic of your board?
Others around here are stronger than I, but you mentioned Q1-Q3 - I’d triple check the orientation of those and ensure correct components.
Again, someone (or you) will come up with the other thing(s) that may still be lurking in your Lola.

Bottom line, once you track it all down and button it up, she’s a real beaut of a pre!

 

[Toobme]

Triple check the soldering on the input jack for the DI. Or reflow it. Measure everything. Check continuity.
Re-go-over the troubleshooting guide.
And it will come.
Fingers crossed!

 

[Toobme]

I just built another Lola last weekend, and one of my DIY990s was toast.
After searching under the lens, i saw i’d cut a trace when nipping a lead.
Actually succeeded in putting a tiny jumper (piece of a cut lead) onto it as a replacement trace and it worked.
I will build a new 990 but for now, that will do.
Like Hairball says - the opamps are half the circuit, so check those too!

 

[Tronfxdx]

The Good, the bad, and more bad.

The Good - This sounds incredible. I used the BA-512 op amps. My Mellow Audio u87 clone sounds amazing with this thing.

The Bad - Having issues with the meter bridge so I will have to figure that out.

The more bad - I am ordering another one. I MUST have a pair of these!

Happy building!

 

[Djuicy]

Hi everyone

I just started building mu Lola last night. It seems like a very fun build. Unfortunately I'm afraid I shortened the connection between R2 and R3. I've tried to desolder with no luck.

It looks a bit like there is a connection between R2 and R3 in the pcb, but I'm not sure. Can anybody confirm this, or should I just start over?

Happy building

 

[kato]

You can remove the bridge by running a hot iron between the pads. Solder will stick to your iron and wipe it away.

You can also do this on the pads with excessive solder.

 

[Echo North]

Those pads are connected on the PCB. So no worries.

 

[Djuicy]

Thank you for your help, I will continue then!

 

[sr1200]

Anyone know what the mic input impedance is on the lola?

 

[Echo North]

Specs...

Controls and Switches: Mic Gain, Output Level, Phantom Power, Phase, Mic/Line, Di, Average and Peak Metering


Microphone Preamp Gain: 15.5dB to 65 dB (4.5dB stepped with output trim)


Microphone Mode Maximum Input Level: +13 dBu, balanced, < 1% THD


Line Mode Maximum Input Level: +25 dBu, balanced, < 1% THD


DI Input Maximum Input Level: -1 dBu, unbalanced, < 1% THD


THD + Noise : < 0.05% (1 kHz, 50 dB gain, +17 dBu output)


CMRR: > 90 dB (40 dB gain, 20 Hz to 20 kHz)


Maximum Output: +30 dBu balanced, 20-20 kHz, >1.6k ohms, <2% THD


Frequency Response: +/- 0.5dB 20 Hz – 20K Hz (-40dB, 1K input, 0dB output)


Current Draw: 130mA max


Microphone Input Impedance: 1.6K #, balanced line-to-line


Line Input Impedance: 10K #, balanced line-to-line


DI Input Impedance: 1M#, unbalanced line-to-ground


Output Impedance: 200#, balanced line-to-line


Metering: 10 Segment LED bar graph


Metering Scale: -20 to +3 VU (0 VU = +4 dBu)


Metering Modes: Average and Peak