8 Channel, 3U NEVE 1073 completed

[3nity]

On Behold of Bluzzi i'm glad to let you know that 2 more 1290 are out from the intensive room!

They sound nice and quietly!

Bad toroidal.

Jorge Aristondo.

BTW: 1290CM coming soon.

 

[Bluzzi]

Thanks Dr. Jorge.

Guys I gave my 1290s to Jorge a day ago because we could not figure out what was wrong with my wiring or grouding etc. They passed audio but had small annoying hum.

Now Trinity has figured out that it was the Toroidal XFR that was bad! So I was punishing myself for nothing.

I haven't heard them yet but I trust Dr. Jorge. Apparently he transplanted the bad XFR with a good one and presto! Working Neves!

I just got in and found this out via here and various private messages from him so I will be picking them up soon and listening to them.

This problem had me stop all my DIY including my 1084EQ project so I can't wait to put these pres in my studio.

On to the MP-2 pres now!

Jim

 

[madriaanse]

Super cool!! Enjoy the preamps!! :thumb:

M.

 

[madriaanse]

Hi Everyone,

One of our members ran into a situation where the EZ1290's would go into oscillation at higher gain. I asked if he could send me some pictures of his build, and it turned out the input transformer was too close to the output transformer, and no shielded wire was used. After he followed my recommendations of spacing the transformers a bit more and using shielded wire the problem went away and the preamps performed flawlessly. Here are some pics of his layout *before* he fixed it.

Hope this helps.

M.

 

[mfdu]

i just need to check in about input and output transormers.

i've got two ez1290's and two jlm baby animals in a box, with the 48v jlm psu and his 24v zener to supply to the ez1290's.

what are the specs of the carnhill input and output transformers? or what does the board expect to see?
i hope i have some strange old units to suit.

chunky 10ohm:15ohm outputs and 7.3ohm:63ohm inputs (below - not the green cans Astors)

but i just can't seem to find the actual resistance readings or whatever it is i need to know so i can unmask the hidden secrets of the transformer world and

oops. sorry.

here's a construction photo, but i'm lazy and haven't got an internal case shot. but i'm using a 3RU case with chunky handles - it looks the biz.

 

[mfdu]

OMFG

i just read a revised build PDF which details cutting particular pins from the middle row of the greyhill switch

oh no!!! that wasn't in my older build manual (page 5 http://musiciansgig.com/ez1290/assembly2.pdf )

i haven't trimmed off the specified pins. neither have they been soldered in - there were no pads to solder to!

is this going to be an issue??? i've been dragging my feet to final hookup, and then come up with concerns around the transformers.
now this.

chris.mfdu

 

[madriaanse]

Hello Chris,

Use this assembly guide:
http://musiciansgig.com/ez1290/assembly.pdf

The version you referred to is for an earlier, prototype version of the EZ1290's.

Thanks,

M.

 

[mfdu]

cool. so the one you referred me to doesn't specify trimming off the un-soldered pins on the greyhill switch.

just as b%@@dy well.

but mate - there is still no info on the actual readings of the input and output trannies.

not even whether the input is a 1:6.5 or 1:1, and whether the output is 4:1 or 1:33.
can you give me some kind of idea of whether my trannies are even close to the requirements?

chris.mfdu

 

[bobschwenkler]

[quote author="madriaanse"]One of our members ran into a situation where the EZ1290's would go into oscillation at higher gain. I asked if he could send me some pictures of his build, and it turned out the input transformer was too close to the output transformer, and no shielded wire was used. After he followed my recommendations of spacing the transformers a bit more and using shielded wire the problem went away and the preamps performed flawlessly. Here are some pics of his layout *before* he fixed it.
[/quote]

I'm curious if this was feedback due to inductive coupling between the input and output transformers?

 

[madriaanse]

Chris,

Check this link: http://www.technicalaudio.com/reading/neve_xfmrs/neve_edo7113.html

As a note, if you want a Neve 1073, it's Carnhill or bust IMO. Sowter may also be good but I've never tried those personally.

bobschwenkler,

When I did some experimentation with transformer placement for my 8ch unit, I could get the mic pre to oscillate at max gain by holding the mic input transformer next to the line output transformer. And this was WITH shielded cable. So I think inductive coupling is definitely something to pay attention to. Also, the mic pre's will easily oscillate if you hold an unshielded mic in wire next to an unshielded line out. Best to follow the Neve spec and use shielded cable as well as space the transformers a bit.

Best Regards,

M.

 

[3nity]

Channel one of my pair is sounding nice but i haear a small hum...but hum goes away when i touc the front panel?

what could be wrong here?

Thanks.

 

[mfdu]

sounds like a grounding issue. do you have ground from pcb to case to power earth inlet and XLR input ground? (ie. full star-grounding)?


yeah yeah - i know it won't be a 1073 without carnhills. but it isn't anyway, is it? i'm gagging to use these old trannies i've got, and if they sound sweet then thats all i'm concerned about.

hopefully i'll do final hookup this weekend and report back.

chris.mfdu

 

[3nity]

What i did was XLR in # 1 to Go beetween ground.....
And since i didnt use Carnhill i went ground directly from Shield to XLR out #1.

But no #1 to star ground.

 

[madriaanse]

Chris,

yeah yeah - i know it won't be a 1073 without carnhills. but it isn't anyway, is it?

It is; pay attention to parts and there's no discernible difference. However, experimentation's a lot of fun, and I am curious about your transformer findings.

3Nity,

Try leaving pin 1 on the output XLR disconnected.

All the best,

M.

 

[3nity]

thanks gonna try!

 

[mfdu]

madriaanse - no offense meant. it's just the whole DIY thing, you know?

i mean, i'm looking forward to seeing how the trannies sound. but i have nothing to compare the sound to. not being the proud owner of any n*ve gear.

hopefully i'll knock them up today.

chris.

 

[madriaanse]

[quote author="mfdu"]madriaanse - no offense meant. it's just the whole DIY thing, you know?
[/quote]

Hi Chris,

None taken! I just wanted to clarify and probably should've stuck a smiley somewhere :thumb: .

Let us know what you learn about those transformers!!

Cheers,

M.

 

[Whoops]

Amazing Stuff.

I would like to buy 2 boards for this project if you still have some. Sent you a pm.

thanks

TS

 

[zachs]

Love it, I'm setting up to build a sweeeeet 4 channel unit in a 2U or 3U depending on what's actually going to fit them all. Sneak peek below of some ideas I'm working on, I think I like #2 & #3 the best with no borders. I think building in the 3U might be easier too.

Any feedback on these panels?

I'll be using the JLM Go Between to add pad and phase to Martin's design as well as the JLM Power Station V2 to run all 4 units easily. Pricing this out so far including all the best stuff including Marconi knobs, a 4 channel unit is only looking like it's around $1500...

 

[Whoops]

They look lovely. great work.

I also prefer the 2nd and 3rd.

How did you design them?

Will you use front panel express to make them?