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

[Echo North]

Built a Lola today with two 990. It's the forth I am building and seems the first to have issues. First problem is in the Grayhill. It seems to have a very small amount of gain from ccw to cw (this in LINE mode). In MIC mode is unusable, with phantom engaged you have to put the gain at maximum and output too to have just a couple of white leds moving.
Other issue in the DI section: completely no sound. Where could I begin for troubleshooting? Thanks.

Do you have other opamps you can try?  I would start there, rule out that it's not an op-amp issue.

Mike

 

[frenkonio]

Got a couple of original 2520 from Api. Will try them tomorrow. But I don't think DI issue and Grayhill issue may depend from that.

 

[frenkonio]

Ok, spotted. One of the two 990's is not working. How could I understand why? All transistors are in the right place, no diode reversed, inductors ok  and main output transistors are ok (171 on Q9 and 181 on Q8). All resistors are of the right value and no solder problems (cleaned with isopropyl alcohol and a toothbrush).

 

[Echo North]

Ok, spotted. One of the two 990's is not working. How could I understand why? All transistors are in the right place, no diode reversed, inductors ok  and main output transistors are ok (171 on Q9 and 181 on Q8). All resistors are of the right value and no solder problems (cleaned with isopropyl alcohol and a toothbrush).

I don't have a lot of trouble shooting info on those. Usually I just build a new one. The schematic is on the MNATs site.  You can check the transistors for B-E voltage drops (about 0.5V) and test the diodes for a drop.  It would have to be one of those or a bad solder joint.

Make sure the clips are not touching the diode leads.

Mike

 

[alexkfong]

Hi, newbie here that's built a couple of electronics projects (including a DI), but nothing as complex as the Lola, which I just started building.

Right now I'm stuffing the DIY 990 opamp. For the TO-92 Transistors, the manual says "put the shrink wrap tubing over the transistor" ... but I can't find tubing anywhere in either of the opamp kits that comes with a single Lola kit. And does the tubing go on the leads? I'm a dummy! Can someone point me in the right direction?

Thanks!

 

[Potato Cakes]

Hi, newbie here that's built a couple of electronics projects (including a DI), but nothing as complex as the Lola, which I just started building.

Right now I'm stuffing the DIY 990 opamp. For the TO-92 Transistors, the manual says "put the shrink wrap tubing over the transistor" ... but I can't find tubing anywhere in either of the opamp kits that comes with a single Lola kit. And does the tubing go on the leads? I'm a dummy! Can someone point me in the right direction?

Thanks!

First, this definitely isn't a good project for a newbie, especially building op amps. Believe me, I did the same thing years ago and it was very frustrating....

There is a picture on the Hairball site in the build guide that shows where the shrink tubing is supposed to go.

http://library.hairballaudio.com/datasheets/DIY-990-Manual.pdf

Thanks!

Paul

 

[Echo North]

It should be in the bag with the clips.  Its only a 1/4 ring of shrink tube.

It's not critical, just get the faces of CR3 and Q3 touching.

Mike

 

[alexkfong]

Mike and Paul:  Thanks for the clarification.

I was looking at the build PDF on my phone and didn't see the tubing in the picture. Zoomed in on the PC, it's quite clear that I'm not looking for, like, a little piece of wire tubing. I definitely see what I need now.

Paul, I don't disagree that this a major project for starting out. But you gotta begin somewhere!

 

[Jannunziato]

Did you meter to make sure proper voltage is getting the the meter board? If the preamp and DI are working properly, then the problem is on the meter board or the at the header on the main board going to the meter board. Should be pretty easy to find as the problem area is narrowed down significantly.

Thanks!

Paul

I have the same problem. Seem to have a good connection between the main board and the meter board (continuity from header solder points to header solder points on the meter board). The pre and di work great. Sound great. Using the John hardy op amps. Next step is to recheck the ic soldering joints. I made sure the ic’s were correct and placed correctly. At a loss at the moment. Would love some ideas on what to check next. What worked for other people in this situation?  Thanks.

 

[TillM]

check, if all ic's in the right direction.
Measure the voltage on the ic pins and tell us what the DMM shows.
It maybe sounds funny, but I had a meter problem, because I don't push the cable not strong enough in the header.

 

[Echo North]

If all the IC's are in the right places (don't mix up the TL071/TL072) and all the components and soldering looks good, it may be a bad 1N914. They tend to be very sensitive to solder heat and handling. A lot of meter repairs I do end up being one of those.

 

[Abwproaudioservices]

Help  :-\

My blue 48v push button stays on no matter if its pushed in or not

 

[Echo North]

Help  :-\

My blue 48v push button stays on no matter if its pushed in or not

Does the 48V turn off and on?

Either a short or a bad switch.

Mike

 

[sr1200]

seems like one of my LOLA'a (the newest one) has been bitten by the bad FET problem on the DI...  I noticed the schematic has j201 and you provided 5457's  in the kit.  Any reason for the change?  5457s are getting hard to come by since ON seems to be the only company making it now, and they seem to be drop ship from factory only at mouser. (others are marked obsolete) and the J201s are about 4x the price of the 5457. 

Is there any alternative (even swapping out the support components) for the FET buffers?

 

[Echo North]

seems like one of my LOLA'a (the newest one) has been bitten by the bad FET problem on the DI...  I noticed the schematic has j201 and you provided 5457's  in the kit.  Any reason for the change?  5457s are getting hard to come by since ON seems to be the only company making it now, and they seem to be drop ship from factory only at mouser. (others are marked obsolete) and the J201s are about 4x the price of the 5457. 

Is there any alternative (even swapping out the support components) for the FET buffers?

Hi,

We've sorted the FET issue. You can email us for a new set of 5457s.

We have a bunch of them that don't meet our requirements for the FET/RACK and FET/500 stuff. We were using those in the Lola. Turns out some of them (higher IDSS) don't work.  We've eliminated those FETs from the kits as of about 2 weeks go. All should be good now.

Mike

 

[sr1200]

Emailed.  Thanks Mike.  If theres an alternate, i might have something laying around the shop that might do the trick and save you a buck on postage.

 

[Echo North]

Emailed.  Thanks Mike.  If theres an alternate, i might have something laying around the shop that might do the trick and save you a buck on postage.

Hard to say without testing.  Only one for sure would be Fairchild 201s.

Mike

 

[eelcobakker]

Hi all,

I've recently built a Lola with BA512 opamps . All functions (pad/48v/DI/meter) seem to work fine, but the output sound has a very nasty distortion. I've swapped the opamps around but this makes no difference.
What can I try next?

I have another Lola which I still have to build, (and a finished Elements Bronze which works just fine), so I have some other opamps on hand.

Thanks,
Eelco

 

[Echo North]

Hi all,

I've recently built a Lola with BA512 opamps . All functions (pad/48v/DI/meter) seem to work fine, but the output sound has a very nasty distortion. I've swapped the opamps around but this makes no difference.
What can I try next?

I have another Lola which I still have to build, (and a finished Elements Bronze which works just fine), so I have some other opamps on hand.

Thanks,
Eelco

Make sure you have the output fully clockwise.  Yes try a different set of op-amps.  If that fixes it, swap them around until you can find the bad one.

Mike

 

[Ethan1997]

Having some issues with my newly built Lola. The second of my diy 990s got screwed up somewhere along the way and burned up r36 and r37. Im planning on ordering a new 990 to replace it (as i found the diy option was a bit beyond my skill level) but does anyone have the mouser part id for those 10ohm resistors? (Still a noob with component identification, sorry if this was a dumb question)