8 Channel, 3U NEVE 1073 completed

[nikonet]

thanks zachs, so.......there no solution.........about this noise at 70db :'( :'( :'( :'(

 

[zachs]

Perhaps you're having more noise than usual, I'm not sure... best for Martin to chime in.

What are you recording at 70db gain that's quiet enough to hear it? What mic as well?

 

[3nity]

thats is normal...if you got the gain at last position of switch....and i doubt that in practice you need that much gain.
And yeah theres some hiss but nothing to worry about when recording.
Do you have your toroidal on an external case or in the same case?

 

[madriaanse]

Hi Nikonet,

Just to make sure your noise floor is normal, can you record something with this preamp, and with another preamp you have; maybe upload the clips?

Thanks,

M.

 

[YLab]

''the transformers (and tantalum caps) probably have the greatest single effect on the sound''

Hey Martin, are you thinking about a particular brand of tantalum caps other than the kemets on the BOM.

Thanks
Hubert

 

[zachs]

Alllllllmost done with mine... had a freaking cap blow in the Power Station last night on the first hook up, scared the blimey out of me my god, my ears were ringing for 20 minutes. Not sure what caused it, I've been going back and forth with Joe from JLM. He thinks backwards cap, but I'm 99% sure it wasn't. I've got the center pin jumped to Doubler.

I removed the rest of the blown cap, powered again and it's ok. Looks like I now need to replace the cap, resistor and regulator. Ugh. Double check your work I suppose. Perhaps it should be quadruple.

 

[madriaanse]

Hey Martin, are you thinking about a particular brand of tantalum caps other than the kemets on the BOM.

Hi Hubert,

The Kemets sound lovely!

Zach: that's some SERIOUS phantom power you're getting there.... what are you seeing on the secondary of your power transformer (AC voltage between green and blue)? What's the DC voltage after the rectifier, before the regulator? Check with a fine-toothed comb for incorrectly placed components and solder bridges.

M.

 

[zachs]

I think we got it figured out, turns out the phantom is about 66.8 – so looks like the reg is just gone. I think I was originally measuring AC and not DC for the +48. Voltage from 0V to both AC ins was 25.5.

 

[Bluzzi]

Don't feel too bad. I blew my JLM by connecting my 0v to the center terminal! I didn't look at the schematic that one time and I presumed 0v would logically be in the center. WRONG! Blew 2 resistors and 1 regulator. All back to normal now. Oh yes also I hadn't soldered the jumper so I was getting erratic measurements.

Jim

 

[3nity]

JLM stuff is awesome!

But i managed the V+ regulator to not regulate enough....it was putting 24V, when loaded with a 1290 it fall down to 19V....not good sounding.
then i set the 48V to +24 and the sound great.....what happens??

See i left out the V- parts...but putting them in the pcb fix the problem.

 

[zachs]

Martin: I'm using a lighted rocker switch from Mouser

http://www.mouser.com/Search/ProductDetail.aspx?R=YRM32F2BBRLNvirtualkey54010000virtualkey540-YRM32F2BBRLN

I'ts switching on the power but not lighting up, I think I need to do something with the prongs on the other side but not sure. It looks like:

| |
| |

And I've got my wiring hooked up to the left side, 1 & 2.

 

[madriaanse]

Hi Zach,

Neutral goes to either 4 or 5. Verify that you measure resistance between 2 and 5 before connecting anything to power.

M.

 

[YLab]

He!

I'm looking at the schematic of a compagny that make a popular neve clone and i can notice somme differences with the org. schematic. Here are some questions that i have if someone is willing to anwser them.

1- 100p instead of 180p accross the input transfo.
Is that to extend the top end??  This clone utilize the same input transfo than the ez1290.

2- 22uf tant instead of 10uf tant in front of the first bc184 of the input and output section.
Is that to extend the low end??

3- They suggest to put a loading resistor (620R) on the output.  If im going directly into my soundcard that have a 24k input impedence when balanced, should i care about putting a loading resistor??
I'm asking this because i've just notice that inside my api 3124, there's a place to put an ''optional 1k loading resistor''!!

Hubert

 

[zachs]

Whatever the specs are in Martin's 1290 design I think are all true to the original design. Not sure what other clone you are referring to.

 

[YLab]

Whatever the specs are in Martin's 1290 design I think are all true to the original design. Not sure what other clone you are referring to.

Yes,, i know that Martin's 1290 is true to the original, i'm just trying to understand what those value changes can do to the sound of the preamp. You know, i'm far from being a electrical engineer  ;D
The compagny i'm refering to is s c a.

Hub

 

[zachs]

Anyone have quick tips for measuring the TR3 Collector voltage? I'm not really sure I'm doing it right.

 

[3nity]

All DC voltages  are taken from 0V to the desired spot!
http://www.musiciansgig.com/ez1290/transistor_voltages.pdf

Usually put the positive lead over the screw...

 

[zachs]

Err maybe because I didn't have my output trannies hooked up to the board?

Hopefully the last thing, on the trim pots, pot #3 goes to the front 10k space, pot #2 goes to the L Jumper; does pot #1 go to the other 10k space, then you jump the 10k space to the P Jumper hole? I'm looking at the drawing now, just not sure how you connect those two together.

 

[wolfgang]

This wiring for the trim-pot should be ok !

I also want to know how a 600R Termination on the OT would affect the sound.
Read somewhere that on the old consoles the modules were loaded with 600R and now we are running the modules in 10K gear.
Could somebody explain pro and cons for terminating with 600R? Is it necessary?

best regards,
Wolfgang

 

[zachs]

My question was mainly about how to wire to the 10K spot, do I just go to the front 10k and the jumper or does something go to the back 10k as well?