8 Channel, 3U NEVE 1073 completed

As one of those who magically had his oscillation problems resolved by grounding the board to the case through the mounting hole, I have to say that I later got oscillations again. It's been ages and I don't remember any more what it was from, but I just looked at it now and in it's current state (still frankensteined, waiting for a facelift) it's grounded through a 10R to PSU ground which is tied to the case. I don't think this will let me use phantom as is, so I'll have to eventually change it (when I build the 2nd channel and it gets a facelift).

I agree on the paint removal, your problems sound like interference (your hand coming close to the gain knob) from improper/incomplete shielding. Grab your multimeter and check for continuity between all case panels.

It is hard for someone to tell you how to ground your equipment without a clear understanding of how it's set up (how many channels, what PSU, etc.. a good hi-res picture is sometimes better than words). Grounding is not so much a "star" as it is a  "tree"with branches. Grounds go down to earth(ground pin of your IEC connector), which would be the trunk of the tree. Each channel or PCB is a branch and its ground goes back to the trunk. It can either walk along the branch and get to the big tree trunk and safely climb down or it can try to jump from branch to branch and maybe hurt itself. When you have two branches connected together and to the trunk, it doesn't know which way to go and that's a ground loop. 

For this build, you want your 0V going to PSU ground and PSU ground going to case (the infamous "star" ground) THROUGH a 10R resistor.

mitsos said:

I don't think this will let me use phantom as is, so I'll have to eventually change it (when I build the 2nd channel and it gets a facelift).

Click to expand...

I have phantom running fine here w/JLM Go Between's and ACDC/Powerstation. Inputs and 48v are all tied to the same 0v connection.

Hmm, I just looked at it again and you're right. My pin 1 is connected through the trafo to the PCB so phantom will get it's 0V from there.

The way i had it hooked at first was so wrong.  I had all kinds of problems. Once Joe explained a couple things about the proper wiring layout...it all came together.

I dont know if this would help but i have a bunch of pics of my build using the JLM gobetweens and the JLM PS.  (also used the JLM VU drivers)
http://www.facebook.com/media/set/?set=a.1817484879991.104345.1326207212&l=f66b9d117c
Its a public album on facebook, you dont need a FB account to view.

Thanks a bunch for all your help..
Im going to try to use plastic standoffs for all my PCB's incl the JLM PSU today, as some of you recommends and see what happens.

Heres a picture (the psu is not mounted in the case here)


Heres a hi-res image of my build:
http://cybercraft.dk/neve-hires.jpg

Curious. What do you have the tripler/doubler hooked up to on the JLM ACDC? Normally there's just a jumper in there.

It doesn't look like you have ground hooked to anything? The two yellows on the tranformer primary are hooked to power, but there should be a third wire that goes from your case to that plug that is ground!

You don't have to use plastic standoffs everywhere(although they are cheaper) just the one hole that is connected to 0v on the acdc pcb. That should be plastic...and glued on(or any other non-conductive method). The hole by the trimmer pot.

Once you have your ground hooked to the case and your acdc screwed down to the case...you should be able to measure 10ohms between any shield or 0v connection to the case.

any more boards left to order? Would like to order 4

Curious. What do you have the tripler/doubler hooked up to on the JLM ACDC? Normally there's just a jumper in there.

Click to expand...

I wanna know the same thing... looks like that part of the board is hooked up to an input???

I think the wiring here is all sorts of not right.  What re the inputs on the board wired to its not the input transformer...

Off the top of my head... The input jack hits the JLM go between, the go between outs to the Input Trafo, the input trafo outs to the board, the board outputs to the output trafo and that outs to the output jack.

The JLM PS takes the 3 wires from the IEC, the 0v and 48v go to the go between, a 0 and 24v go to the boards (i didnt daisy chain any of mine)

The PSU is not hooked up to any input. Its looks weird i admit, buts its just a home-made jumper. I made it so i could easily test the jumper settings on the PSU board because i had no idea what to do with it.. I can see it looks weird on the picture..
The inputs XLRs are hooked up to the go-between kits, and from the go-between kits to the input transformer, and from the input transformer to the main PCB. The output from the PCB goes to the output transformer,and from there to the output XLRs.
The PSU outputs 0V, 24V and 48V and its not daisy chained to the two PCBs but drawn separately from the same points on the PSU.

Im pretty sure my problem is that i have no ground from the power input (I told you im bad at this ). I will try it out this week. One thing though: There's two mounting holes on the JLM PSU board thats is marked "case" Should they both touch ground then?

Thank you for your help so far.. I really appreciate it!

Michael

Just use either of the ground points on the psu

Hi...
Just finished my definitive PSU2 box....    to power two 8-channels racks...  so 16 Channels.
with optional fan on back panel (depend if i need it to be totally quiet or no)
using conductive standoffs.... no problem.
Desol, i finally used the wiring that Joe gave me...

Sylvain

front power Off

front power On

Back Fan/power Off

And Back Fan/Power On

Hey all,

I just realized that the gain between channels 1 and 2 in one of my 1272's is almost exactly 10 dB different. In other words, when one is set to 50 dB, the other has to be set to 40 dB to output the same level - but it's like exactly the same when they are set that way (as seen on a scope).

Any idea what might be the most likely culprit for this?

It's this way all the way up the scale, so it's not just one resistor in the gain-switching network... I used all 1% resistors and everything all through the build. I was thinking maybe a bad transistor? Should I start yanking them out and replacing with better matched ones?

Thanks in advance!

Hey Statzern, to narrow down the problem can you measure the level at the L-P junction of each pre-amp?
This is the point where a trimmer would be inserted if used and would allow you to see if the different level is due to the second or third amplification stage. I don't think the first amp stage is at fault as this only kicks in for the higher gain settings and you are observing the difference across the whole scale. Cheers, Briomusic

Already posted in the other 1290 thread, but no reply, so retry here:

Hi all

Iam soldering the parts on my EZ1290 at this moment finished soldering the parts on my EZ1290s but I have run into a two little problems:
1. I did not recieve R56 (resistor 12 Ohm 1W). But I got two extra R98 (resistor 10 Ohm 1W).
Can I use the 12 Ohm in place of the 10 Ohm?
I have bought in a local shop two 12Ohm 1W resistors, but they are twice the size (see pic) ...will fit though, but Iam wondering.. are they a different kind of resistor?

2. I have an empty space on both boards labelled 3k3. I do have two 33Kohms resistors, but they are not the ones right? Or can I use these anyway?

Input highly appriciated!
Thank you in advance...
Erik

I have a question about noise - how much noise is normal for these units?

I mean I understand there is this phenomena known as "Neve Haze", and I am also aware that finding a good HFE level with the choice of transistors will affect the noise, but I get this white noise /ssshhhhhh sound on the last three steps of the grayhill.  As I have no experience with a real Neve module, I cant determine whether this is just normal Neve Haze or whether I have an issue with my build. Some people seem to report "no noise" on the builds however.

I dont hear any hums or sound reminiscent of ground loops, and I solved the osciallation problem (high pitched squeels) by grounding the 1290 pcb to the rack case, but there is still that soft sssshhhhhhhh sound at the last three highest volumes.

Can anyone enlighten me?