[Hairball Audio]

I finished my unit and have been using it for some weeks now... I noticed the meter lights flicker when i turn the PPM/VU switch up and down, but it doesnt give me readings when im tracking... Does it only work in line mode or i made a mistake somewhere?

That's an error on your meter PCB somewhere. 

- Check that the two small IC the TL071 and TL072 are inserted in the right spots and direction.  They are not interchangeable.
- Check that your diodes and polarized caps are oriented correctly.
- look for solder bridges

Mike

[okgb]

I made the mistake on mine where i let too much solder flow underneath the l.e.d. on the component side
so I couldn't see it , but used a 9v battery with a clip & resister to double check the l.e.d.'s were all in correct
and working ,so unsoldered , resoldered and all was well [ not a trivial task ]

[patterson]

Just built the first of two Lolas.  It sounds great. 

Thought I'd share two issues I had.  The first is that I mistakenly switched the output transistors on the OA.  That burned the 10r resistors.  Once I put them in the right place, the unit worked fine.  Lesson: read the great manual. All of it.

The second is that there was hum when I turned the gain way up for dynamics like an SM7.  I searched the internet and came across a thread that the transformers on some lunchbox cases can interfere with some modules in the 6th bay.  I traded it for another module in bay #1 and the hum disappeared. 
Very happy.

[Hairball Audio]

Just built the first of two Lolas.  It sounds great. 

Thought I'd share two issues I had.  The first is that I mistakenly switched the output transistors on the OA.  That burned the 10r resistors.  Once I put them in the right place, the unit worked fine.  Lesson: read the great manual. All of it.

The second is that there was hum when I turned the gain way up for dynamics like an SM7.  I searched the internet and came across a thread that the transformers on some lunchbox cases can interfere with some modules in the 6th bay.  I traded it for another module in bay #1 and the hum disappeared. 
Very happy.

I was chatting with Ed Anderson the transformer designer about the shielding within the input transformer.  He mentioned that because of the shield, the design, and usage in this circuit, the 10468 should be well guarded against hum.  He also gave me a heads up about the pre 2007 API lunchbox power supply.  The power transformer in the early lunch boxes was undersized (non torrid I believe) and under full load it would toss a lot of interference.  Later they replaced the transformer with a larger torrid capable of supplying more current.

For reference the "new and better" power supply was first installed in Lunchboxes in Jan or Feb of 2007 with serial number 501.2352 and higher.

http://www.gearslutz.com/board/so-much-gear-so-little-time/468154-api-6b-lunchbox-power-supply-improved-when.html

If you get a chance I'd be curious to know which version you have.

Thanks!

Mike

[bulghur]

I finished the kit and it sounds great through the mic inputs and through the DI on low level signals.  I am getting distortion on the DI on line level inputs like synths (Prophet, TR909, etc.) and have to turn their outputs WAY WAY down the output -- there is a lot of sensitivity and little wiggle room.  I figure that I am overloading the FETs.  My objective is to leverage the sound of T1 rather than piping the high level line inputs in through the mic inputs and a passive DI.  How should I think about Padding the input if I want to use it against line level inputs.

[Hairball Audio]

I finished the kit and it sounds great through the mic inputs and through the DI on low level signals.  I am getting distortion on the DI on line level inputs like synths (Prophet, TR909, etc.) and have to turn their outputs WAY WAY down the output -- there is a lot of sensitivity and little wiggle room.  I figure that I am overloading the FETs.  My objective is to leverage the sound of T1 rather than piping the high level line inputs in through the mic inputs and a passive DI.  How should I think about Padding the input if I want to use it against line level inputs.

The DI input was designed for passive instruments like guitar and bass.

Have you tried using the Mic input with "Line" mode enabled?  Line mode swaps the pri/sec of T1 giving you a 14dB(ish) pad and still runs the signal through T1.

[lowend]

Hi !

I just finished yet my Lola preamp !
And my only problem is the grayhill knob ! I cant mount it ! I really dont understand the manual If someone can explain me please

[Hairball Audio]

Hi !

I just finished yet my Lola preamp !
And my only problem is the grayhill knob ! I cant mount it ! I really dont understand the manual If someone can explain me please

The knob is set up for a 1/4" shaft, but the Grayhill used is a 1/8".  There is a 1/8"->1/4" spacer provided.  The knob has two set screws.  You want set screw to travel through the slot in the spacer and make contact with the Grayhill shaft.  You want the second set screw to make contact with the spacer.  That will keep it all in place.

I start by placing the spacer and turn one set screw so it goes through the slot.  Then I set the other set screw tight against the spacer  not unscrew the one through the slot, slip the knob on and retighten the one that goes through the slot.

Mike

[lowend]

Hi !

I just finished yet my Lola preamp !
And my only problem is the grayhill knob ! I cant mount it ! I really dont understand the manual If someone can explain me please

The knob is set up for a 1/4" shaft, but the Grayhill used is a 1/8".  There is a 1/8"->1/4" spacer provided.  The knob has two set screws.  You want set screw to travel through the slot in the spacer and make contact with the Grayhill shaft.  You want the second set screw to make contact with the spacer.  That will keep it all in place.

I start by placing the spacer and turn one set screw so it goes through the slot.  Then I set the other set screw tight against the spacer  not unscrew the one through the slot, slip the knob on and retighten the one that goes through the slot.

Mike

Ok thanks Mike ...
that's what I'm doing I think... but maybe my problem is my allen key... I got 1,5mm and 2 mm but the screw looks to be 1,75 mm.. I can not block it as well...
I will find a solution !!

Thanks again mike

[mistasanshou]

Has anyone tried swapping in some jensen trannys?  I really want to buy this as my fast/clean/detailed pre and am trying to decide between this an a forssell smp 500.

[Hairball Audio]

Has anyone tried swapping in some jensen trannys?  I really want to buy this as my fast/clean/detailed pre and am trying to decide between this an a forssell smp 500.

Haven't tried, but if the core/bobbin is the same size it should be no problem.  There is an optional zobel for that purpose.

[shabtek]

 I built up 2 with alternate input and output transformers: very nice---use what you got

[okgb]

I build mine " stock " and don't get the feeling of anything lacking or
that I'd want it to be , It's just plain Good ! [ & unquestionable ]

[mistasanshou]

Hmmm... im probably wrong in my asumption but ive always heard that the jensens were as close to transformerless as you were going to get.  So I assumed this would make the pre even faster and cleaner.  Also I have so many pres with ed anderson transformers it makes me a little weary of adding yet another..  Any help would be greatly appreciated.

[Hairball Audio]

Hmmm... im probably wrong in my asumption but ive always heard that the jensens were as close to transformerless as you were going to get.  So I assumed this would make the pre even faster and cleaner.  Also I have so many pres with ed anderson transformers it makes me a little weary of adding yet another..  Any help would be greatly appreciated.

Transformer design has more to do with that.

The EA stuff is reproduction work of classic designs, so the the transformers can vary widely in their sound.  Ratio has a great affect on transformer performance.  Something like the EA-10468 which is wired like 1:1.65 in the Lola will have much less distortion than a higher turns ratio like a 1:5 or above.  A low ratio mic input is a completely different sounding animal than a high ratio mic input.  That's one of the advantages of the 990 op-amp, it actually prefers a low ratio input tx.

In addition, having two op-amps in parallel driving the 1166 output will improve its performance.

Mike

[mistasanshou]

Makes perfect sense.  Thank you.  I was more or less looking for a preamp in the john hardy/great river mp2h/forssellfamily and it seems this will work perfecty. Off to order one. Thanks again

[lowend]

 I cant mount the grayhill knob ! I dont know how you do all... If someone can make a little video maybe or something... I think I understand the manual.... but I dont know why, I can't !
I'm desperate !

[Hairball Audio]

I cant mount the grayhill knob ! I dont know how you do all... If someone can make a little video maybe or something... I think I understand the manual.... but I dont know why, I can't !
I'm desperate !

Ha!  Give me an hour or two to wake up and I'll make a video for you.

Mike

[Hairball Audio]

http://www.youtube.com/watch?v=xqkhiRM0KPU

Try that.  The video is sideways right now, but it's in processing to be rotated.

[lowend]

oh Mike ! You're so nice ! Thanks !!
I will try soon !

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