8 Channel, 3U NEVE 1073 completed

[zachs]

Either wattage is fine I believe, I think someone else asked the same thing recently, or similar. No ground to box from pin 1.

These will have a little sound at 70db, here's what Martin has to say about it which seems fine.

Like all 1073/1290's, these preamps have some hiss ("Neve haze"). They are not dead quiet, but the hiss shouldn't be distracting unless you're recording quiet sources with ribbon mics. The noise floor specs can be improved somewhat by hand-picking BC184C's for highest HFE (especially the first one in the darlington config), but I never bother.

 

[madriaanse]

1/2 W or 1W are both fine for the 47R.

making XLR holes: By far the easiest/cleanest way to go is to use a 15/16" Greenlee punch (predrill w. 3/8"): http://tinyurl.com/825fqg
Then I put the XLR connector in the hole, use a square to align the XLR with the chassis, mark the holes for the 4-40 screws, centerpunch and drill. Even better is to befriend a guy w/ a CNC lasercutter!!

I don't sell the Grayhill switches. You have to get those from Audiomaintenance.

All the best,

M.

 

[zachs]

How does that punch work manually, just predrill, put the bolt through, finger tighten and it grabs the metal enough for you to use a ratchet you bring it all the way through? I thought you had to have a hydraulics for those, that's pretty cool if you can do it otherwise.

 

[madriaanse]

Hi Zach,

exactly. That's how it works if you use a ratchet. It works even better (and very fast) with an automotive impact wrench. You can punch a hole in seconds.

M.

 

[zachs]

Cripes I should have bought one of those instead of my $60 stepped Greenlee bit! Oh well, great tip thanks.

 

[mitsos]

Hi, has anyone built this using metal film resistors? Just wondering since I have tons of them around, or is the 5% carbon thing part of the sound? Is it to stay true to the original specs? thanks!

 

[Whoops]

Metal Film 1% all the way!!!!!!!!!!!!!!!

 

[mitsos]

OK, was just wondering because the parts list seems to call for 5% and people here say to stick to it as closely as possible for the most "neve-like" sound.

 

[trancedental]

Many Guitar Tube Amp builders, for example,  prefer to use carbon film resistors in most places. Metal film is good for higher values, like 470k or even slightly lower and & of couse above that value, to keep down the hiss. So I'm assuming that the pres would have more of "retro" sound with carbon films although the transformers themselves would have more influence on how the output signal sounded.

Maybe Madriaanse & other experts on here can give us some advice?

 

[Gachet]

Hi there

Is it possible to wire the input transformer primary in parallel for line level operation?
Or is there another trick?

Thanks

 

[madriaanse]

The reason I chose carbon resistors was twofold: 1. The original module I used as a clone source used carbon; it was a stellar sounding module. 2. carbon's cheap. I know Neve also used metal film later in their production, so you can use either and still be "authentic". Like trancedental mentioned, the transformers (and tantalum caps) probably have the greatest single effect on the sound.

All the best,

M.

 

[madriaanse]

Is it possible to wire the input transformer primary in parallel for line level operation?
Or is there another trick?

How about a Go-Between from JLM: http://www.jlmaudio.com/JLMDI.htm

M.

 

[Gachet]

Hi,

Thanks for answer.
I will use the pad idea with 470R but what is the 120R parrallel resistor for?
What is the parrallel wiring of the transformer  for? Z=300ohms instead of 1K2
Maybe for ribbon or other low Z mike ?

Thanks

 

[madriaanse]

I will use the pad idea with 470R but what is the 120R parrallel resistor for?

Together with the 470R's it makes a U-Pad, see: http://www.uneeda-audio.com/pads/

What is the parrallel wiring of the transformer  for? Z=300ohms instead of 1K2
Maybe for ribbon or other low Z mike ?

That is correct. Supposedly it works well for ribbons; however I just leave mine at 1200. I have an AEA R88 on the way from Mercenary and I'm going to try 300 ohms with that.

M.

 

[Whoops]

Is it possible to wire the input transformer primary in parallel for line level operation?
Or is there another trick?

How about a Go-Between from JLM: http://www.jlmaudio.com/JLMDI.htm

M.

Martin , with the JLM DI you would have a DI input and not a Line in.

In the Neve 1073DPA they are doing the Mic in and Line in with only one input transformer, so it would be nice to see how did they wire it up.


It would be nice to be able to change the inpedance of the pre-amp, it's cool for ribbon mics and also to play around with dynamic mics.
Anyone knows how to do that?

 

[mitsos]

You just swap your input trafo primaries from serial to parallel. Putting them in series you get more turns on your primaries which gives you a lower turns ratio (and higher impedance primary). Putting them in parallel gives you half the turns on the primary side, so it doubles your turn ratio, and makes your primary impedance four times lower.

In practice, you get the 1K2 impedance by tying the + of one primary to the - of the other and using the other + and - as the primary connections. In parallel you tie your +'s together and your -'s together and are left with the equivalent of one winding.

 

[madriaanse]

Martin , with the JLM DI you would have a DI input and not a Line in.

Oops, sorry you're right. For some reason I thought JLM had a line-in plugin for their Go Between.

In the Neve 1073DPA they are doing the Mic in and Line in with only one input transformer, so it would be nice to see how did they wire it up.

From what I've heard (don't quote me on this), AMS bypasses the input transformer alltogether on the line-in and uses an IC line receiver to go directly into the pre-stage. I personally wouldn't go this route and prefer the traditional 31267 setup.

It would be nice to be able to change the inpedance of the pre-amp, it's cool for ribbon mics and also to play around with dynamic mics.
Anyone knows how to do that?

Yes - it takes one DPDT. Check out S1 on: http://www.technicalaudio.net/neve/neve_pdf/1073-EH10023.pdf

Cheers,

M.

 

[Gachet]

I will use the pad idea with 470R but what is the 120R parrallel resistor for?

Together with the 470R's it makes a U-Pad, see: http://www.uneeda-audio.com/pads/

Thanks for the documentation...very useful
To achieve line to mic attenuation and impedance the two series resistors should be 7500R and the parallel one 150R.
Maybe I can build the preamp with both 20db and 40 db pad selectable.

What is the parrallel wiring of the transformer  for? Z=300ohms instead of 1K2
Maybe for ribbon or other low Z mike ?

That is correct. Supposedly it works well for ribbons; however I just leave mine at 1200. I have an AEA R88 on the way from Mercenary and I'm going to try 300 ohms with that.

M.

I think I'll put this as an option on the front panel.With a toggle switch it may be craky with audio out on so i'll try relay switching and 1n4148 diodes as long as i have a spare psu rail.

 

[zachs]

Quick question: Can I add a 24V lamp on the front panel just by tapping off of the 24V going to a channel?

 

[Gachet]

Quick question: Can I add a 24V lamp on the front panel just by tapping off of the 24V going to a channel?

Yes you can