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

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Echo North

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Please post any questions, comments, or build suggestions.

Purchase Link:
http://Hairballaudio.com/lola

Manual and Assembly Guide:
http://www.hairballaudio.com/LolaPP/LolaManual.pdf

Overall.jpg


The Story of Lola:
The Lola was conceived a few years ago during a conversation between Ed Anderson and I regarding designing a project for the then new EA-10468 and EA-1166 transformers. I worked on it sporadically in 2010 and extensively in 2011.

Rather than creating another single op amp or 2-stage pre, Ed suggested a fully differential design using two op-amps. The topology is based on the classic 3 op-amp instrumentation amplifier (in this case the output transformer is the third op-amp) and Cohen’s Double Balanced design. Though certainly not a new concept, it does allow us to see how the topology would perform with two discrete op-amps and the artfully crafted EA-10468 and EA-1166 transformers. The stock Lola includes two John Hardy 990C discrete op-amps.

The Lola maintains a completely deferential signal path from input to output. The benefits to the topology are lower noise, through use of the differential design, and a high CMRR common with this topology. It also allows us to take advantage of the excellent balance of the EA-10468 input transformer. In addition, because there are two op-amps in parallel, available output drive current is increased, lowering output impedance; improving output transformer performance and increasing the maximum undistorted gain. In this regard it’s similar to running a single op amp design on 24V rails.

The gain stage provides 65 dB of clean gain in 4.5dB steps utilizing a Grayhill rotary switch. The 600Ω Bourns t-pad on the output allows the user to fine tune the gain setting. There are three illuminated pushbutton switches to select phantom power, phase and line mode. Activating the relay controlled line mode flips the input transformer making it a step down input. This allows the user to use the Lola on line level material. A pad has not been included due to the low ratio and large adjustable gain of the Lola. A 1:1.75 ratio input means the Lola has a lowest gain setting of 16.5dB reducing the need for a pad.

The DI accepts a ¼” unbalanced cable. Inserting a cable activates a relay that controls DI/Mic in circuitry. The DI passes through 2 FET buffers creating a differential signal to feed the 10468 input.

The light pipe LED meter has selectable VU and Peak metering. Though the VU mode is actually average metering (90% of RMS), it’s calibrated to VU metering with little effect on peak mode. 0dB on the meter scale represents +4 (1.23V) in VU mode. A simple resistor change allows the user to have 0dB equal to 0dB (0.775V) if preferred. Peak mode displays the peak value of the waveform in the same scale.

The front panel and L bracket are made in the USA . As a nod to the original 10468 input transformer, the durable front panel is finished with a “hammered” powder coat. The knobs are machined aluminum and have plenty of grip for the Grayhill rotary.

The Lola comes in 3 kit options (pricing will be announced shortly):
1. Complete kit with ever part you need to complete the build including 2 John Hardy 990C op amps.
2. Complete kit without op amps
3. Bare bones metal work and PCBs only.


Internal Shot:
guts.jpg


Simplified Block:
http://www.hairballaudio.com/diy_images/Lola-Block.jpg

Lab member Bieckmusic was kind enough to record and post sound files.    They can be found here:
http://www.groupdiy.com/index.php?topic=28923.msg599577#msg599577

Some Lola related discussion can also be found here:
http://www.groupdiy.com/index.php?topic=47566.msg599814#msg599814

On a personal note I'd like to thank Ed Anderson for being a wealth of knowledge and an all around awesome guy..  I'd also like to thank Classic API Jeff for kicking in advice and wisdom and repeatedly asking me "You got that pre done yet?"

Hope you guys like it.

Mike
Hairball Audio, LLC
Seattle, WA

ps. Lola is one of my dogs.
 

Echo North

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dandeurloo said:
How many dogs do you have?  :)

Looks great and great price Mike!

Thanks!

I have two along with the Hairball logo cat.  Unfortunately, the other dog will not have a product named after him.  The "Woody" is just a little too lowbrow for me.  ;D
 

Echo North

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Paultec said:
Nice work, Mike...

I'm sure this sounds great....

....what's with the "Hammerite" panel?

P:)

It's a nod to the old Marinair 10468 that was finished with a hammered paint.  I can promise you it looks very cool in person ;)
 

Echo North

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Heads up!

The plan was to release the Lola mic pre next weekend. Unfortunately, there was a problem with the frontpanels so I need to have them re-made (Boooo). Luckily they are putting a rush on it and I should have them in 3 weeks. This means the Lola release is delayed 14-20 days. It should be set to launch the week of April 9th.

Thanks all!
 

Echo North

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GroupDIY friends. In a couple of hours I'll be sending out the mass Lola release announcement. Grab yours now! There are a limited amount w/ Hardy 990's.

http://hairballaudio.com/shop/index.php?cPath=35
 

Echo North

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Messages
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pH makes a strong point indeed  :D

Just found this in the Hairball archives.  Lola V 1.0 circa summer 2010.

lolav1.jpg


She worked about as good as she looked.
 

mnats

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Jun 3, 2004
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Australia
Lola_003.jpg


He's pretty much the Mike Holmes of audio DIY. I've never had anything go together so smoothly.

Other than a stupid mistake I made before the manual was finished everything went together perfectly.
 

okgb

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Oct 18, 2004
Messages
5,808
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Winnipeg Mb Canada
Got my kit , it really does look super cool in person
initial sound impressions , strikes me as Clean & thick at the same time
thick cleanish or clean thickish ?  and quite quiet when you do crank it
way higher than you'd ever use , what little hiss you do hear seems to have a
different quality than usual , definitely different feel , Nice !

WARNING  reading the instructions all the way through IS helpful !
my excuse is I dislike reading on the laptop . [ and need glasses ]
DO NOT solder the  output attenuator or d.i. jack flush to pcb
the manual tells you this , but I thought I was on a roll and plowed through
before fully reading , I recovered though to record another day .

Thanks Mike , great piece of kit as the brits say
Also very well packed [ how many kits did you have to sort ? ] I almost want to keep the box
the package is so nice


 

Echo North

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Jan 21, 2006
Messages
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Awesome!

Ya making the kits is a ton of work.  Probably more work than if I just soldered the parts on!

Glad you like it.

Mike
 

bobine

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Jan 4, 2010
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SoCal
Clean and thick was my initial impression, too.  A "tough" sound. 

Now to finish the meter board and live with it for a while.

I let one pin on the T pad miss the hole and fold under, but that was the only hitch.  Just need to go slow there.
 

Echo North

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Messages
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bobine said:
Clean and thick was my initial impression, too.  A "tough" sound. 

Now to finish the meter board and live with it for a while.

I let one pin on the T pad miss the hole and fold under, but that was the only hitch.  Just need to go slow there.

On a prototype a while ago, I soldered the T-Pad frame pins but not the actual leads.  Took me like 30 min to figure out why my Lola wasn't working .

Mike
 

shabtek

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Jun 8, 2005
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2,026
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midwest usa
I've got 2 parts sourcing questions;
on the meter pcb, what is the part#\source for
1)light pipes
2)toggle switch

anybody else finish one of these--cheapskate version minimal kit or pcb only version




 

Echo North

Well-known member
Joined
Jan 21, 2006
Messages
4,433
Location
Seattle, WA
shabtek said:
I've got 2 parts sourcing questions;
on the meter pcb, what is the part#\source for
1)light pipes
2)toggle switch

anybody else finish one of these--cheapskate version minimal kit or pcb only version

1) LMC040CTP (Visual Comm)
2) T201MH9ABE (C&K)

I sell the toggle on my site.  I can also sell you the light pipes if you like.

Thanks!

Mike

 

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