Dual 1073 style micpre & EQ in 1u

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chipss36

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https://ibb.co/w0shygv
Looks like I am first.
Still working on the build, very impressive David.
Power rails are running fine, made a few changes to bom, solid shaft potmeters, center detent on cut boost pots, went all vishay 1813 on caps, becuse of ocd, still curve tracing transistors, have a few old bc184c’s
With good hfe levels.
All the new ones on bom, but ordered a few mpsa18’s, noise and gain on data sheet look impressive on them, want to test a few.
Still not sure what I will use yet.
 

Category 5

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Jul 24, 2004
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Palm Beach, FL
Just stumbled on this project and though I don’t need another mic pre (I’ve got 48 channels already!). I can hardly resist.

Anyone experimented with alternate parts?  I see a lot of parts from the mouser cart not available, so it’s going to be multiple vendor orders anyway.

I have a 24v/48v power supply in an old gen 1 sca rack that has been on the garbage pile for years but managed to stick around. It would be perfect for this. 

Anyone who has completed a build please share your thoughts, or talk me out of this!
 

Category 5

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Well, I'm all in for two channels of 73+.  Mind blown by the attention to detail.  How is this not everyone's project right now?  Rupert himself would dig this implementation.

Waiting on a ton of parts that are on the way but PSU and output trims done.



 

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chipss36

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I need to finish this up, mouser in the USA was indeed back ordered on a few parts,  I left it all in back order so others many have them parts in stock, I also wanted all vishay caps so subbed some caps, transistors I am still
Not set on, I have some old nos that have much less gain than say mpsa18’s
Same with the 2n3055, I have curve traced what I have and am still not sure what in the end I will do,..
 

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Category 5

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Looks very nice chipss.  I decided that life wasn't difficult enough, so went about sourcing old mustard caps for mine.  It was expensive and tedious.  Anyone looking to do the same, I recommend avoiding anything rated above 160V.  Even the 160V parts are huge for the higher values.  I had to get creative and build in 3D.  I have two sets of boards, so I will do one with 1813s and compare.  I doubt there will be much actual difference.  Even with the vintage caps I was able to get them matched into pretty close pairs, surprisingly.  Also, I recommend you sand the leads a little and use plenty of flux.  Solder does not like to stick to old, oxidized leads at any temperature.
 

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Category 5

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I finally got the rest of the parts I was waiting on and finished this bad boy up.  I had to improvise on a couple of parts that just don't seem to be coming back in stock this year.  I decided early on to source all vintage mustards, underestimating the size of the larger values.  In hindsight, I probably wouldn't choose that path again.  MKT1813 are known to be analogous, easy to source, and fit perfectly.  I could not find a reliable source for BC184, so I use BC550 and BC549 throughout.

Design and fit of all these parts is damn near perfect.  I can tell David put a ton of time into the development of this project.  It's not cheap, or simple when all is said and done, but it's probably the best no-compromise Neve project I have seen.  No wiring!  I was going to try and get some vintage transformers, but they are going for just ridiculous prices now.  I can't imagine who is paying $500 for lo1166 but I wouldn't go over $300, and even then I'd feel a little bit taken.

The preamp sounds incredible, as does the EQ, as expected, but the one big surprise here is the DI.  It sounds amazing, and has quite a neve-esque air about it.  I plugged in my strat just to test it, and found myself loving the tone I got straight through my interface and focal solos.  This is my new favorite DI folks, and I barely took note that one was included when I decided to do this build.  I plan to do a second unit, this time with all modern caps.  David will sell you a second set of boards if you want to experiment with different types.  The modules pop in and out just like op-amps.  This will also make it easier to diagnose issues withe the amplifier modules themselves too.

 

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Category 5

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I made a little 3d printed saddle and used some bus wire to secure the EQ switches.  Grayhill makes a fine part specifically for this task, but it is impossible to get, and stock is nowhere in sight.  This worked just as well, and IMO is not a compromise at all.
 

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Category 5

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I also decided to print these little spacers to hold all the boards at even height.  David recommends soldering a few of the sockets closed for this task, but I chose a different approach.  Maybe I just really wanted to play with the new 3d printer.
 

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Category 5

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Thanks guys.  David at DON Classics did an amazing job putting this together.  I can't believe it's not more talked about on here.

About the cost, the mustards didn't help, and I made so many separate orders all over the place, it's hard to calculate but it's in the 2's, and maybe even close to 3k (USD).  It's well worth it though, if you ask me.  The boards and metalwork are very refined, and the modular design is a great idea, especially for experimentation and troubleshooting.  The look is just awesome, but the sound is fantastic.  This isn't DIY for the sake of saving a buck.  It's DIY for the sake of building something better than you can go out and buy.  I talked myself out of a pair of vintage lo1166 many times, but they are just so inflated now I don't think there's any value there.  You could easily spend 4K if you wanted vintage iron though.

There is an extra (hidden) mid band, probably up around 8k too, which is cool, and the 1084 HF band is a cool option.  It's really just a few extra caps on the main board, a grayhill, and a pot.  The DI, which David says he designed as he imagined RN would have done it, is something special as well.

 

mike

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Nov 27, 2011
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This is an awesome project - can't believe I missed this until today!

One thing, I think I'm missing how line in is used on this design - the only 1073's I've used have had a separate input for line - some with a 3rd transformer as the original and some with a switch for line/mic (reversing the transformer for line). On this design, it looks like you switch to line input at the 0db mark (I assume reversing the transformer) but turning the gain up at all you switch to mic in. Does this mean that line in can only be used at unity gain and you cannot drive or attenuate the line in with the gain knob? Only attenuate at the output? Or am I missing something? which is quite likely :) lol
 

Category 5

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There is a separate DI module that feeds the mic input transformer. It is automatically switched in by a local relay, when an input is sensed. David told me he designed it as though he thought Rupert would have designed it, at the time. It's probably one of the best parts of this project. It is my favorite DI for bass and guitar alike.
 

mike

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There is a separate DI module that feeds the mic input transformer. It is automatically switched in by a local relay, when an input is sensed. David told me he designed it as though he thought Rupert would have designed it, at the time. It's probably one of the best parts of this project. It is my favorite DI for bass and guitar alike.
I saw the DI input which is great for bass or guitar! I'm more talking about using it as a line level EQ or as an input for (lower level) line level instruments. I currently am using an HA73EQ and what I like to do is use it as an insert for EQ in my DAW but have the option to drive it a little. Great for printing things which need warmed up a little. Or as a line amp on the master bus to eq and then drive a compressor. I also use the line in for instance, recording a 909 kick into my DAW which sounds like heaven when driven just a tad. Or really any other synth or drum machine. I could use the DI input for the synths, but I don't know I'd get the same tone exactly, plus going behind the rack every time I had to record something would be a pain.

I'd love to build something of more quality than the HA but I'm not sure if this will work for that specific need or not, or If I'll have to go a different route like something with the hand-wired elma 24 pos switch and 2 input xformers more like a vintage unit.

At this point I feel like it sounds like I'm complaining, lol but I'm not meaning it that way! This is a great project either way and I'll likely build a pair even if I can't drive the line in. But I would build one with the 1084 top end instead of a straight 73. Or maybe the 1066+ - that looks tasty :)
 

Lakewood

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May 7, 2017
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Hey,

this build looks awesome and I'm already building the rack unit for two 2NV73 units!
As all the 2NV73 versions are currently out of stock, does anyone has infos when the kits will be available again?
I already wrote an email to donclassics about 2 weeks ago but didn't got an answer yet!

Kind regards, Leo
 
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