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

[allthebigtrees]

Hi,
Just bough the Lola pre and i was ready to do the meter on it but wanted to try it to be sure there was no problem on the lola.
Of course there was one haha.
Plug it to my lunchbox and nothing comes out of it.
The lights of the 48v, phase and line light up when i push them.
but turning both gain and trim doesn't do anything. not even
So first i try a different preamp so there's no problem with the mic and xlr, then another spot on the lunch box to be sure the problem cam from the lola.

After reading a bit on the forum, one of the main suggestion was to verify everything and then resolder every component that seems odd.
Every resistor seems to be a the good spot, color wires match with their spots, etc.
I redid 30% of the soldering that seem not "great".
Retried nothing, again no output...
Do you have any suggestion where to look at for that kind of problem.

Thx a lot

 

[Potato Cakes]

Do you know for certain your op amps are working?

Thanks!

Paul

 

[allthebigtrees]

wow thx for the fast reply!

I double checked the op amp. still nothing coming out of it...
When i put everything on max i can hear a noise and that's it.  Nothing through the line input too. trim seems to work on the noise haha but that's it.
Its weird when i do small taps with my fingers on the lunchbox i can hear my taps through the preamp even if i unplug the microphone and nothing more....
Tried to record it and the sound come with a lot of distortion.
Now i just really confused.

 

[Potato Cakes]

I meant do you know for certain your op amps are working?

Thanks!

Paul

 

[Echo North]

If you built your own op-amps, I would expect you have an error in your op-amps.

 

[allthebigtrees]

Hi,
I tested both op-amp and they all seems to work fine...
Check the image bellow on a 2 channels oscilloscope.
Boosted the gain to about 1.5 using an non inverting schematic.
I'll check on the main board to check if there's a problem
If you got any idea where the problem might be let me know

 

[allthebigtrees]

After some research, I can find that nothing is reaching the op-amp.
There's something odd with the resistance at r22 and r25.
There's a shortcut over there but i can't find anything odd on my soldering.
And without the schematic i don't really know where to look at.
Is there a way to have access to it?
Or do you have any clue what is going on

 

[Potato Cakes]

Does the DI work? Do you hear the relays clicking when you power the module on and off? One time I had a bad solder joint on the 1/4" jack and it was stuck looking for the DI instead of the IN+/- (XLR).

Other than that, it's very difficult to diagnose the classic "no sound coming out" problem with actually looking at it as it could be almost anything. Usually it's a bad/missed solder joint or a misplaced/misoriented component. Make sure you are getting proper voltages at the op amp sockets. Sometimes it takes a couple of days to see obvious problems.

Thanks!

Paul

 

[allthebigtrees]

Tried with the Di and the XLR input. no one works
I can hear the relay clicking.
i will check again for bad soldering

 

[Echo North]

Tried with the Di and the XLR input. no one works
I can hear the relay clicking.
i will check again for bad soldering

You can email us for the schematic. It is rare, but possible you have a bad input transformer.

Measure the DC resistance between one of the green wires and then each wire individually.

Mike

 

[0rgazm0]

Well i built my 5th ok... now i had a fail on my 6th.  Mic works ok, all buttons/controls work ok,  but the DI is off. It's kinda scratchy sounding. A waveform looks like the + part is ok but the - part is barely there and flat. I flowed a little solder to the 6 di jack points and its the same. Before I just remove all the solder and redo the DI jack completely would there be any other points to check for this?

thanks again

 

[Echo North]

Well i built my 5th ok... now i had a fail on my 6th.  Mic works ok, all buttons/controls work ok,  but the DI is off. It's kinda scratchy sounding. A waveform looks like the + part is ok but the - part is barely there and flat. I flowed a little solder to the 6 di jack points and its the same. Before I just remove all the solder and redo the DI jack completely would there be any other points to check for this?

thanks again

Sounds like a bad FET buffer.  Send us an email.

 

[IMUTHANT]

Hey there, happy user of 2 LOLAs for the past 5-6 months. Not sure when these problems started (maybe I didn't notice them immediately after the build), but on the first LOLA, the VU setting on the meter doesn't ever light up. Set to PPM, however, it works fine. On the second LOLA, I get the faintest signal coming through (and maybe a bit of noise?) when the gain and output pots are all the way down. The first LOLA is fine though, and no signal comes through when at its lowest settings. Thanks!

 

[Echo North]

Hey there, happy user of 2 LOLAs for the past 5-6 months. Not sure when these problems started (maybe I didn't notice them immediately after the build), but on the first LOLA, the VU setting on the meter doesn't ever light up. Set to PPM, however, it works fine. On the second LOLA, I get the faintest signal coming through (and maybe a bit of noise?) when the gain and output pots are all the way down. The first LOLA is fine though, and no signal comes through when at its lowest settings. Thanks!

Noise:

1)  Try swapping their positions in your rack. One might be closer to a noisy supply.
2)  Swap the op-amps...see if the noise follows the op-amp.


Meter:

The meter is surly something off on the meter PCB.  Check all the solder joints and values.

Mike

 

[Acotler]

Hello All,  I'm new to this site, but so far I'm really liking what i see.  So here is my reason for posting (I'm a bit of a rambler, but hopefully more info is better than less):

After having two Lolas at the studio for a year or so, I decided i liked them so much that i ordered two more kits.  After putting the first kit together i realized it was missing the gain knobs (of course the knobs were the absolute LAST thing I looked for).  I put in a missing part request over the weekend, and went on my way... to the studio

After a little testing  I realized that while the mic input and phantom power are working great (I tried a 57 and a condenser), I'm having some issues with the DI. I haven't put a scope on it yet since I don't have a fixture for bringing power outside the lunchbox, and probing while inside the lunchbox is a bit tough, but from the sound of it i would guess that I'm clipping one of the JFET buffers in the DI path.  Basically the output sounds a bit "thin" compared to the other Lolas, and starts to distort with any reasonable amount of gain.  Also, the metering is a bit weird.  I don't know if I'm imagining it, but it seems like when I'm using the DI with the meter set to vu, the output level is quite low (-10dB-ish at my DAW) when I'm hitting the meter in the red.  The mic inputs are usually about -5 or -6dB on the DAW when the meter on the lola is just below red, so this seemed odd.  I would have thought that the metering for the mics would be at the same point in the circuit as the metering for the DI.  This leads me to my first question: 

Where are the Lola schematics available for download?  I was able to find the 990 schematics on this chain, but so far haven't found the main board, or meter board schematics.

To troubleshoot I double checked all my passives in the DI chain, and all the values/color codes look to be correct (also I did measure everything with the DMM before soldering).  To make sure there wasn't a cold solder joint somewhere I reflowed everything I could get an iron on, and the problem persists.  It seems likely that I must have damaged one of the JFETs during install.  I wasn't using an ESD mat, I wasn't grounded when handling the parts, and I was using a big ol' wedge tip on my iron so I could have damaged one of them either way...

I went on the hairball site to order some replacements and realized I wasn't sure if I needed the unmatched, matched, or stereo matched pair.  So finally, my next question: 

Can anyone recommend a JFET pair to order, and explain what audible differences there will be between the 3 options?  What's the real advantage of a matched pair in this circuit?

Also, for anyone at hairball who reads this, is it already too late to tack the JFETs on to the shipment of the gain knobs?  I'm happy to pay for them since it seems likely that neither of the JFETs were bad before i put a hot iron to them.  I haven't received my shipping email for the knobs yet, so I'm hoping i catch you before the they go out.  Thanks in advance!

-Austin

 

[Echo North]

Hello All,  I'm new to this site, but so far I'm really liking what i see.  So here is my reason for posting (I'm a bit of a rambler, but hopefully more info is better than less):

After having two Lolas at the studio for a year or so, I decided i liked them so much that i ordered two more kits.  After putting the first kit together i realized it was missing the gain knobs (of course the knobs were the absolute LAST thing I looked for).  I put in a missing part request over the weekend, and went on my way... to the studio

After a little testing  I realized that while the mic input and phantom power are working great (I tried a 57 and a condenser), I'm having some issues with the DI. I haven't put a scope on it yet since I don't have a fixture for bringing power outside the lunchbox, and probing while inside the lunchbox is a bit tough, but from the sound of it i would guess that I'm clipping one of the JFET buffers in the DI path.  Basically the output sounds a bit "thin" compared to the other Lolas, and starts to distort with any reasonable amount of gain.  Also, the metering is a bit weird.  I don't know if I'm imagining it, but it seems like when I'm using the DI with the meter set to vu, the output level is quite low (-10dB-ish at my DAW) when I'm hitting the meter in the red.  The mic inputs are usually about -5 or -6dB on the DAW when the meter on the lola is just below red, so this seemed odd.  I would have thought that the metering for the mics would be at the same point in the circuit as the metering for the DI.  This leads me to my first question: 

Where are the Lola schematics available for download?  I was able to find the 990 schematics on this chain, but so far haven't found the main board, or meter board schematics.

To troubleshoot I double checked all my passives in the DI chain, and all the values/color codes look to be correct (also I did measure everything with the DMM before soldering).  To make sure there wasn't a cold solder joint somewhere I reflowed everything I could get an iron on, and the problem persists.  It seems likely that I must have damaged one of the JFETs during install.  I wasn't using an ESD mat, I wasn't grounded when handling the parts, and I was using a big ol' wedge tip on my iron so I could have damaged one of them either way...

I went on the hairball site to order some replacements and realized I wasn't sure if I needed the unmatched, matched, or stereo matched pair.  So finally, my next question: 

Can anyone recommend a JFET pair to order, and explain what audible differences there will be between the 3 options?  What's the real advantage of a matched pair in this circuit?

Also, for anyone at hairball who reads this, is it already too late to tack the JFETs on to the shipment of the gain knobs?  I'm happy to pay for them since it seems likely that neither of the JFETs were bad before i put a hot iron to them.  I haven't received my shipping email for the knobs yet, so I'm hoping i catch you before the they go out.  Thanks in advance!

-Austin

You probably just need tome new JFETS.  Those 5457's are super sensitive to static/heat. Could have even been damaged here when we packaged them. I'll send you an new set.

Mike

 

[Acotler]

You probably just need tome new JFETS.  Those 5457's are super sensitive to static/heat. Could have even been damaged here when we packaged them. I'll send you an new set.

Mike

Thanks, Mike.  Fingers crossed that the JFETs are the problem.  In case they aren't do you have the main board schematics posted somewhere so I can troubleshoot?

 

[Echo North]

Thanks, Mike.  Fingers crossed that the JFETs are the problem.  In case they aren't do you have the main board schematics posted somewhere so I can troubleshoot?

I just added it back to the build guide. It's after the tools section at the start.

Mike

 

[tata]

Lola is such an awesome preamp.. but you already know that.

i had zero (electric related) problems with building it  - i just have a question : what resistor to change if i want to adjust the meter sensitivity?

here is my build:

thanks

 

[TillM]

Lola is such an awesome preamp.. but you already know that.

i had zero (electric related) problems with building it  - i just have a question : what resistor to change if i want to adjust the meter sensitivity?

here is my build:

thanks

Hey Tata.
good to see that you finished it !
Nice build !