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

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porkyman said:
i had been using the lola for a few weeks without the meter working and it sounded great. i decide to fix the meter (hadlock  the two ic's switched) and now its making this crazy siren noise when i hook it up. like an old ham radio searching for frequency. even without any signal running through. it makes absolutely no sense because i didnt touch the main pcb at all. i even disconnected the meter ribbon and it still does it. 

any ideas
Click to expand...
Do you have the Hairball 990s?  Make sure you don't have upright components touching each other.  This can happen accidentally when you remove the modual.
 
yes i have lola 990"s. i checked all components. nothing touches. this is the weirdest part. i switched them out with gars and the noise is gone but the gain switch stopped working. i also tried 1 in 1 out in each slot and its not just one 990. the noise happens with either one in either slot. how can they both go out in the same way at the same time for no reason?

i was trying to feel around for some excessive heat. thats how i found the last problem i had, but its a little scary leaving it connected when its making that noise so i didnt have it on for more than 30 sec.
 
i dont know if this has anything to do with anything but while i was messing with the doa trying to see if they were sitting properly i discovered if i touch my two fingers to q3 and cr3 and the L2 inductor of the middle doa it would trigger the di relay and the noise would stop. if i did it on the outside one the relay wouldn't trigger and it would still stop the noise. however stopping the noise didnt produce a clean signal, it was still distorted and super low volume..

also i forgot to mention before switching doa's didnt produce a clean signal. its hard to say if its distorting because i have the output gain all the way up just to hear anything, because the gain switch isnt work or if the low level signal is already distorted.

is there a way to check the gain pot to see if its working properly. i touched all the solder points, and it didnt do anything?
 
I would not be touching anywhere in a live module with anything but  probe.  You're most likely just causing things to ground out.

You've got some bad stuff going on.  You'll need to go through the build carefully looking for solder bridges and missed pads.  A lot of mistakes people make are from missing solder points.

It should work with the GAR and the gain should change which makes me think you have a larger problem.  Sounds like you're getting some oscillations.  I'm suspicious of the DOAs.  Sure the GAR don't change w/ gain switch?

Likely not the switch, or the 990 would behave same as GARs.

We do offer repair service now.  It's $50 plus parts which is generally a streaming good deal is you're interested.

Mike

 
gyraf said:
Question:

We just had two incidents of a Lola killing the -16V line in 51x supplies (we do not know the cause yet) - the schematic in the Lola manual does not show reverse-spike-protection diodes on the supply lines (ya'know, from minus to gnd and from gnd to plus) - wouldn't these be a good thing to include? Or are they already there?

(please excuse me if I'm wrong, just trying to do a quick diagnostics for the guys in our studio)

Jakob E.
Click to expand...

Hi Mike.  I may have  been having a similar issue, although I wouldn't say the -16V line in my 51x PSU has been killed, it is just "changed" down to -14.4V from -16.4V when two (2) Lolas are in the rack. 

Please keep in mind that I am a NEWBIE... so I may not be using the best logic or description for the issue at hand.

Ok- here's the issue I became aware of today.  I just built my 2nd VP28 from Capi and was using Jeff Steiger's test rig to check the Op amp socket voltages prior to installation of the op amps.  I noticed that all the voltages seemed a little off (See Photo below of documented voltages on the VP28) .  FYI I have a 51x rack from CAPI with floor box PSU. 

SO.  I assumed it was the VP28.  pulled the unit, checked over thoroughly, could find nothing amiss.  Then I thought to check the voltages in the rack itself minus this new unit.  Interestingly, Pin 5 to 15 read 15.5 V (not the readings the unit originally had when I built it) and the Pin 5 to 13 read -14.5 V.  Very strange.

So- I pulled out all the modules.  2 X VP25, 2 X Color Palette (DIY-RE), 2 X Lola, and 1X VP28.  Then I re-tested the rack voltages.  They read a nice crisp +/- 16.4V.

So I thought it had to be a module setting things off.  I began to re-install modules.  Beginning with the VP25's.  Retest.  Same voltages.  Then Add Color Palettes.  Retest.  Same Voltages.  Then Add Lolas.  Retest.  VOLTAGES ARE OFF.  + rail in overall rack reading 15.7V or so, and - rail reading 14.4V.  Pull one of the Lolas.  Retest.  Rack is now reading +16V and -15.4V. 

next test.  Left Lolas Out, added VP28.  Voltage +/- 16.4 as it should be.

Seems that the Lola Preamps each drop the neg. voltage 1V, and have a slight change to the + voltage. 

Does this make sense and is it possible?  Is there something that I have done wrong in the build identically between the two Lola Preamps to cause them to alter the entire rack's voltage?  Is there some simple adjustment that can be made?

Also to note- I built all the op-amps from the DIY-990 kits.  Perhaps the problem lies there.

Thanks for your thoughts/suggestions!

https://drive.google.com/open?id=0B85J5nWB03hxRzR6SzY0QXlWSHc&authuser=0
 
juanpavlo said:
Hi Mike.  I may have  been having a similar issue, although I wouldn't say the -16V line in my 51x PSU has been killed, it is just "changed" down to -14.4V from -16.4V when two (2) Lolas are in the rack. 

Please keep in mind that I am a NEWBIE... so I may not be using the best logic or description for the issue at hand.

Ok- here's the issue I became aware of today.  I just built my 2nd VP28 from Capi and was using Jeff Steiger's test rig to check the Op amp socket voltages prior to installation of the op amps.  I noticed that all the voltages seemed a little off (See Photo below of documented voltages on the VP28) .  FYI I have a 51x rack from CAPI with floor box PSU. 

SO.  I assumed it was the VP28.  pulled the unit, checked over thoroughly, could find nothing amiss.  Then I thought to check the voltages in the rack itself minus this new unit.  Interestingly, Pin 5 to 15 read 15.5 V (not the readings the unit originally had when I built it) and the Pin 5 to 13 read -14.5 V.  Very strange.

So- I pulled out all the modules.  2 X VP25, 2 X Color Palette (DIY-RE), 2 X Lola, and 1X VP28.  Then I re-tested the rack voltages.  They read a nice crisp +/- 16.4V.

So I thought it had to be a module setting things off.  I began to re-install modules.  Beginning with the VP25's.  Retest.  Same voltages.  Then Add Color Palettes.  Retest.  Same Voltages.  Then Add Lolas.  Retest.  VOLTAGES ARE OFF.  + rail in overall rack reading 15.7V or so, and - rail reading 14.4V.  Pull one of the Lolas.  Retest.  Rack is now reading +16V and -15.4V. 

next test.  Left Lolas Out, added VP28.  Voltage +/- 16.4 as it should be.

Seems that the Lola Preamps each drop the neg. voltage 1V, and have a slight change to the + voltage. 

Does this make sense and is it possible?  Is there something that I have done wrong in the build identically between the two Lola Preamps to cause them to alter the entire rack's voltage?  Is there some simple adjustment that can be made?

Also to note- I built all the op-amps from the DIY-990 kits.  Perhaps the problem lies there.

Thanks for your thoughts/suggestions!

https://drive.google.com/open?id=0B85J5nWB03hxRzR6SzY0QXlWSHc&authuser=0
Click to expand...

The Lola's are not current hogs.  In normal operation they should be consuming 90-120 mA.  500 series rack modules all share the same supply.  Meaning if your rack power supply can supply 1.5A and is 10 spaces, that means there is an average of 150mA per module.  Some modules may pull more current and some may pull less.  The Lola shouldn't be the issue note should any of those other modules.

I would have a good close look at your DIY-990's.  Generally if they are pulling a lot of current, one of those 4 10Ω resistors around them on the main PCB will smoke or burn.  Check to see if one of those 10Ω R's is brown.  Check to make sure your opamp 171 and 181 output transistors are in the right spots.  Check to make sore none of the vertical parts on the opamp are not touching each other or on of the screws that attaches the diode to the 171/181.

If there is a short on the opamp it can hurt the supply.

Detach the meter see if you still have an issue.

Mike
 
Thanks Mike.

OK.  Did a bunch of testing and looking around.  First off, Turns out I was wrong and I did NOT build the DIY-990's , but ordered all 4 of them prebuilt for $50 each from Hairball.

I removed the op amps from the lolas, re-installed them in the rack and the entire rack (along with all my other modules) read normally at +/- 16.39V.  Measuring the op amp sockets of the Lola (no op amps) yielded favorable results.  O to V+ and V- read +/- 15.8 or so Volts respectively.  So it seems to me that without the op-amps the Lolas seem perfectly normal. 

Is it possible there is a defect in the pre-built op amps?

There are a few small differences on my op-amps from the DIY build guide... R10 & 11 looks like different colors (Org, brn, blk, then mult of red), I calculate this as 31k... but measureing it on the Op amp reads 32.9k so maybe its right?

R13 & 14 are (orange, brown, white, gold, gold)... am I wrong to assume that this value is 31r9?  According to the build it should be 3.9r

I've scoured the rest of the op amp and compared it with the build guide- and it looks like everything else seems right... I can't make out the markings on one input transistor but all others are correct.  I also don't know for sure about the inductors.

Any thoughts to this point?  IIs is correct to assume the problem must be with the op amp since the LOLA itself does not effect a change in rack voltage and the Op amp sockets read correctly?

Thanks!

-JP
 
Hey again! 

After much testing with different modules (and different combinations), etc,  I think we have isolated the rack voltage issue to a faulty voltage regulator in the 51x PSU floorbox itself.  We will know this afternoon when we replace the part and re-test.  As more modules were added to the rack the voltage did in fact drop to the negative rail.  however, when a single pair of Lolas were present in the rack (no other modules), it appeared that the rack voltage was stable at +/- 16.4Volts, as originally calibrated.  Looks like the Lolas are off the hook here!  Pretty darn sure its not the op-amps either.

Much love.

Sorry for the hassle!
 
Further no w to last post- Installed new voltage regulator in 51x PSU for the 16v rail and the entire rack voltage drops only .2V now with 9 modules installed!  Including my new Fet500 :)

Success!  No to finish calibrating the Fet!

Cheers!
 
just for the record. i sent my lola in to get looked at because i couldnt figure it out on my own and Mike hooked me up with the most ridiculous deal.  cant say enough about Mike, this company, and the unit itself. it doesnt get any better.
 
I have gotten to the main PCB testing stage of the Lola Preamp, I blew up R36 and R37, cleaned up shorts/flux, installed new resistors. Yay! No smoke this time.

Now, I am seeing signal on a dynamic mic, and levels change with the input gain knob, but the output knob has no effect at all.

Also, the signal is extremely thin sounding, which I am guessing has to do with the output not functioning fully. Anybody run into this?


Ian
 
Ian Davidson said:
I have gotten to the main PCB testing stage of the Lola Preamp, I blew up R36 and R37, cleaned up shorts/flux, installed new resistors. Yay! No smoke this time.

Now, I am seeing signal on a dynamic mic, and levels change with the input gain knob, but the output knob has no effect at all.

Also, the signal is extremely thin sounding, which I am guessing has to do with the output not functioning fully. Anybody run into this?


Ian
Click to expand...

R36 and R37 indicate something wrong with DOA2.  I'd check the 181 and 171 output transistors and makes sure they are in the right place and that the diodes on them are facing the right way.  Where there shorts on the opamp?

I'd check that and make sure that's ok then report back.

Mike
 
R36 and R37 indicate something wrong with DOA2.  I'd check the 181 and 171 output transistors and makes sure they are in the right place and that the diodes on them are facing the right way.  Where there shorts on the opamp?

I'd check that and make sure that's ok then report back.

Mike
[/quote]

Mike,

I checked the transistor positions/diode orientation of each DOA, all were correct. There were no clear shorts on the DOA, but there was some small rogue solder build up in spots where it shouldn't be, so I cleaned up.  After replacing R36 and R37, and cleaning up the flux and solder joints, I reinstalled the DOAs, and R36 and R37 didn't melt again.

The issue I am having now seems to be related to something in the output section of the pre, as my input knob functions, but the output knob does nothing.

I have DOAs from API512s I could try putting in there to see if it's a DOA issue?
 
Ian Davidson said:
R36 and R37 indicate something wrong with DOA2.  I'd check the 181 and 171 output transistors and makes sure they are in the right place and that the diodes on them are facing the right way.  Where there shorts on the opamp?

I'd check that and make sure that's ok then report back.

Mike
Click to expand...

Mike,

I checked the transistor positions/diode orientation of each DOA, all were correct. There were no clear shorts on the DOA, but there was some small rogue solder build up in spots where it shouldn't be, so I cleaned up.  After replacing R36 and R37, and cleaning up the flux and solder joints, I reinstalled the DOAs, and R36 and R37 didn't melt again.

The issue I am having now seems to be related to something in the output section of the pre, as my input knob functions, but the output knob does nothing.

I have DOAs from API512s I could try putting in there to see if it's a DOA issue?
[/quote]

You could but if just the output is not working it's probably something else. 

Make sure the 39Ω resistors and inductors by the output are in place.  Maybe reflow the solder. 
Make sure the OPTR and OPTC are left empty.
Make sure all the output TPad connections are soldered.  Reflow.
Make sure the output is wired correctly.

Mike
 
[/quote]

You could but if just the output is not working it's probably something else. 

Make sure the 39Ω resistors and inductors by the output are in place.  Maybe reflow the solder. 
Make sure the OPTR and OPTC are left empty.
Make sure all the output TPad connections are soldered.  Reflow.
Make sure the output is wired correctly.

Mike
[/quote]

I threw the DIY 990 that seemed to be working into slot1, and the 2520 into slot 2 (I did this before you responded). Everything works! Then I threw the other questionable 990 DOA into slot 2. Still works great! Maybe my module wasn't fully seated in the 500 rack? Or an op amp/output component lead was leaning on something else? I dunno.

You probably just fixed it with your mind.

This will not be the last issue I have. I can guarantee that.

Thanks Mike!

Ian

 
So far my build has gone great! My Lola is basically finished except for the meter PCB. The problem I'm having is with mounting the Grayhill knob of all things! Its pretty much the same problem I had with the Grayhill on my VP26 I just can't get the thing tight enough! I had it close once and made it all the way back to 17 and when I went to turn the gain clockwise it started slipping again.  It's really frustrating! I'm wondering if I've just totally stripped it out at this point. Although the set screw seems to screw in and out just fine when I'm not trying to mount it on the Grayhill....any other tips? maybe I just need a hex wrench with a little more grip instead of the puny one I'm using? 
 
We actually have 1/8" Lola knobs arriving next week and that will eliminate the need for the shaft spacers (thank god). We can send you one when they arrive.

In the meantime check out this vid and see if it helps:
http://youtu.be/yVQ0pnodZuA

Mike
 

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