500 series mic Pre build suggestions please :)

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buildafriend

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Hey guys. I want to build some 500 series mic pres. Ruling out anything of API decent(since I just finished four channels of API pres), what projects do you suggest? Thanks in advance and regardless.
 

mitsos

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forgot about the G9 group buy. That's another one to try, though I don't know off the top of my head if it's 500 compatible or just 51X.
 

gemini86

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I'm pretty sure my prototype pcbs from zayance are sitting on a pile of stuff at US customs. I did do a new layout that is much more friendly to home etching but relies on hand wiring all the front panel controls. I don't really have the cash right now to build both prototypes so I'm focusing on the pcb version. If somebody is sitting around, bored stiff, I could send them the files to give it a try...
 

buildafriend

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the lola looks really cool. It has 2x 990 discrete op amps but i dont actually understand the purpose of this. it says it is fully differential. I do not know what differential means. I have 8 empty slots in my API 500 rack. I would trade someone my like new API 500 series rack for a 51x rack though I would never personally want to make that trade from the other persons end. 51x is clearly better, and now its getting modular thanks to Igors new 51x chassis design!  ;D

the VP26 pres seem tempting but I really want to avoid API style designs since I have 312s. Some EZ1073 500 format cards would be such a dream come true.
 

buildafriend

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If I could get some guidance as to where to find some nice Neve style 500 format mic pres then I would be extremely happy. I need something that will be a nice icebreaker for building 500 style hardware.

Gemeni: I have 2x the NYD one bottle built up that you suggested, it just needs a few more pieces like a front panel and phantom power added. My friend ran some tests on it and he said it has a strange curve for the freq response. It is totally flat up to 1k and then it has a 1dB dip all the way from 1k to 15k. That thing was such cake to get working. My friend and I got it built and working in about 3-4 hours between theorizing how to build it and smacking the parts together on the bench. I cant wait to get it finished and racked up!
 

okgb

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The sound skulptor  573 in the white market is quite good , complete kit
I've made a few for friends , not sure how it stacks up price wise and it takes
a few hrs just to check & stuff the resisters but it also has a fet di in front of
the input xfmr , so if you're looking for a neve style totally recommend it .
onlyme's  looks good if you're o.k. to source parts there's many out there
if you need to keep a tight budget
 

Echo North

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buildafriend said:
the lola looks really cool. It has 2x 990 discrete op amps but i dont actually understand the purpose of this. it says it is fully differential. I do not know what differential means.

Differential means you have two lines carrying a signal that are opposite polarity from each other.  This should not be confused with "balanced" which means you have two lines with equal impedance.  The lola is both differential and balanced through the pre.  A lot of pre's will convert the differential input to a single signal.

The benefits to the differential design through the pre 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.

Here is simplified block:
http://www.groupdiy.com/index.php?topic=28923.msg598657#msg598657

And more info:
http://www.hairballaudio.com/lola/

Mike
 

buildafriend

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Thanks a lot for the insight mike. It seems like a really beefy product. I wish I knew what 990's sounded like as I have only noted the sound of 2520's. When is the release? How much are the kits?
 

Echo North

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buildafriend said:
Thanks a lot for the insight mike. It seems like a really beefy product. I wish I knew what 990's sounded like as I have only noted the sound of 2520's. When is the release? How much are the kits?

Release will be the 3rd week of March as long as there are no delays with the metal work.  I still need to figure out price.  My gut feeling is that is you want absolutely everything you need to build the pre including two JH-990's it will be close to $400.  However, if you do DIY 990's that will knock close to $100 off and if you have a lot of your own components and get a bare bones kit it'll be even less.  Still need to really do the math though and there will definitely be a discounted intro price for the first week or so.

The 990's are part of what makes the pre unique when paired with the Neve in/out transformers.  The 990 and the EA-10468 are perfect match since the 990 responds better to a low ratio input transformer.  The 990's themselves are a very clean sounding opamp.  Certainly less color than the 2520's.  However, at higher gain settings the color of the transformers becomes more audible.  Greg Bieck who was one of the Lola testers kindly posted some sound files in the Hairball WM thread.  One a double tracked guitar, Lola in one channel and a 312 in the other.  It's not meant to be a scientific experiment and certainly not a "shootout", but it does provide some perspective against a very popular and well known pre.

Hope all that helps.

Mike
 

buildafriend

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It seems like a really cool product. I have decided to build a few 1290s but count me in for a Lola kit when you do the release. I want to take one for a test drive! Do you mind sharing the name of the company that makes your 500 series chassis?
 

Echo North

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buildafriend said:
It seems like a really cool product. I have decided to build a few 1290s but count me in for a Lola kit when you do the release. I want to take one for a test drive! Do you mind sharing the name of the company that makes your 500 series chassis?

I use a local shop and the main reason I use them is because they are local and shipping metal gets expensive.  If you're looking to get some metal done, I would try search locally.  I'm sure there are a number of places in the NYC area that will do metal.  Alumagraphics in PA is one shop on the east coast that has been discussed here before who will do smaller (100 pcs) runs.

Mike
 

mitsos

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Hi Mike,

will you include any of the "standard" transformer footprints (EA2622, not that I'd use a high ratio, but it's a more commonly available trafo footprint, for those who may not want a "neve" type). I know you may want to sell your own trafos with the kit, but anyway, I was wondering.  I like the 990s myself, more than 2520s, but never thought of them as being clean, just real and ballzy. real ballzy.  anyway, in a fully differential circuit is each opamp running at half the gain? For example, in an M1, the 990 runs at 54+ dB, in the twin servo, each 990 does 27+ dB, so ends up cleaner.  From what it seems, each opamp amplifies half the signal, am I interpreting this correctly?

anyway, nice job creating something new, should be pretty cool to test out!
 

Echo North

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mitsos said:
Hi Mike,

will you include any of the "standard" transformer footprints (EA2622, not that I'd use a high ratio, but it's a more commonly available trafo footprint, for those who may not want a "neve" type). I know you may want to sell your own trafos with the kit, but anyway, I was wondering.  I like the 990s myself, more than 2520s, but never thought of them as being clean, just real and ballzy. real ballzy.  anyway, in a fully differential circuit is each opamp running at half the gain? For example, in an M1, the 990 runs at 54+ dB, in the twin servo, each 990 does 27+ dB, so ends up cleaner.  From what it seems, each opamp amplifies half the signal, am I interpreting this correctly?

anyway, nice job creating something new, should be pretty cool to test out!

No they are running at full gain.  Each is amplifying the the signal 55 dB. One on the + side and one on the - side.  The 2nd opamp doesn't provide more gain, it provides 1) fully differential topology which in a few ways reduces noise and 2) increased output drive current (because there are two) which increases headroom and output transformer performance.

You make a good point about transformers.  Having other footprints is something I had originally intended but got lost a long the way.  I'll have to look at this a little.  It may be too late for the first run (or might not) but either way it's something I need to include.

Mike
 
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