useme2305

Re: Neve 1290 build completed!!
« Reply #720 on: August 06, 2012, 02:33:10 PM »
are these boards still available? i had no luck with emailing martin adriaanse. he's either very busy or not selling these anymore? does anyone have some spare boards?

EDIT: successfully ordered two boards from martin.
« Last Edit: August 06, 2012, 05:19:50 PM by useme2305 »


adrian

Re: Neve 1290 build completed!!
« Reply #721 on: August 19, 2012, 07:01:13 PM »
here are some pictures of my 4 channel build,
works perfectly during the last 2 years of FOH touring,
i hope it will continue....

thanks for this great project and for your help!!






buildafriend

Re: Neve 1290 build completed!!
« Reply #722 on: August 21, 2012, 10:26:28 AM »
I love the way the leads come out of the top of those transformers.

Does anyone have an estimate of the cost of this project per channel without the PSU?

I though that the 1290 was a 1073 with no EQ. I read it on the GS forum. I'll have to look at the schematic.

evilcat

Re: Neve 1290 build completed!!
« Reply #723 on: August 22, 2012, 09:35:32 AM »
If I remember correctly, it's about 300-400$ per preamp. Then, the PSU, the case, maybe a JLM "Go-between"... It really worth it, it's an awesome preamp.

best

ben

bluesbaz

Re: Neve 1290 build completed!!
« Reply #724 on: September 12, 2012, 09:36:48 PM »
Hi all I have 4 of these cards and three of them test out correctly but one of them has a huge gain jump and a phase inversion on position 3&4 while 5 only show partial phase offset without the gain. Anyone have any pointers for me? The first three sound super good thanks martin for the great project!
-s

bluesbaz

Re: Neve 1290 build completed!!
« Reply #725 on: September 12, 2012, 10:11:21 PM »
I took a break went back to it and found the issue. The trace from pin3 on deck "U" was a little sloppy on that board and had jumped its way over to pin 4 and pin 5 I cut and cleaned up the traces and jumped things over to the right spots. Things are looking just dandy now.
-s

leitrim_lad

Re: Neve 1290 build completed!!
« Reply #726 on: October 27, 2012, 08:53:03 AM »
not sure if im in the right place but im wondering could u help me. i seem to be having a problem with my ez1290. channel 1 keeps cutting out. it kinda cracks with i talk into the mic and then will cut out. weirdly if i tip the case at the front for example it comes back. if i tip it again it goes again.there is kind of a pulsing noise very slightly in channel 2 as well.. id say they could be related. any ideas of what might be the problem? Cheers, Leo

r2d2

Re: Neve 1290 build completed!!
« Reply #727 on: March 06, 2015, 12:20:30 PM »
helllo ,
looking for info about what type of capacitor
is that placed in the output transformer ,
as indicated  in the attached image
it's :
polyestere ,polystyrene,propylene, ? ..... ceramic ?
thanks in adavance for any help about
R
..... Cracking D.Vader Firewall ...  II-)

beatnik

Re: Neve 1290 build completed!!
« Reply #728 on: March 06, 2015, 12:21:55 PM »
i think it's polystyrene in the originals. 10nF

Re: Neve 1290 build completed!!
« Reply #729 on: March 09, 2015, 06:13:55 PM »


2) I had some issue with crackle. Some people think this was down to the heatsink on the PSU, but I had mine attached to PSU chassis. I remain convinced the crackle was movement in the input transformer wiring. So Im going to use those little fivefish PCBs that sit on the top and allow wiring to be done via a 10pin mollex header.

I have already discussed my crackle woes on the other neve thread, so I wont bring them up in to much detail again here.
I know this is quite an old post but hopefully you will see this.

Read through your issue with crackle as it exactly mirrors my issue.  I spent all day on the issue.  I created a multisim file just find all the specs of the circuit and measure them, no luck isolating my issue this way.  I have multiple psus that I KNOW are good, same issue with all of them. 

Well it turns out, some of the traces have to be soldered on top and bottom, and soldering the 120ohm resistor below the grayhill switch solved the issue.  Incidentally, this also ties the switche's ground to the xlr and power ground.  Probably important lol. 

Pretty dumb mistake for an EE to make lol. 


Re: Neve 1290 build completed!! - Intermittent Ground Hum
« Reply #730 on: June 23, 2015, 06:29:07 AM »
Hello,
New to this forum but have spent many hours reading, digesting and applying the great info here. I have built a 2 channel EZ1290 with external power supply. This works perfectly most of the time, but sometimes I switch it on and there is a prominent 50Hz mains hum in both channels. Once there it won't go away, but after switching off for several hours and trying again it disappears.

I went through my grounding scheme carefully, I have the Mains Earth connected to the PSU case and the preamp case. The 0V from both PCBs are connected to the preamp chassis via 10Ohm resistor. I have used a star grounding scheme in the preamp box.
The PSU case is powder coated so I have had to wire each panel explicitly to ground. I noticed on the schematic for my PSU there is a 10Ohm resistor in parallel with a 0.1uF capacitor between 0V and ground (see picture), should I disconnect this otherwise I have 2 connections between 0V and ground? Will this make any difference?

Whoops

Re: Neve 1290 build completed!! - Intermittent Ground Hum
« Reply #731 on: June 23, 2015, 07:17:16 PM »
Hello,
New to this forum but have spent many hours reading, digesting and applying the great info here. I have built a 2 channel EZ1290 with external power supply. This works perfectly most of the time, but sometimes I switch it on and there is a prominent 50Hz mains hum in both channels. Once there it won't go away, but after switching off for several hours and trying again it disappears.

I went through my grounding scheme carefully, I have the Mains Earth connected to the PSU case and the preamp case. The 0V from both PCBs are connected to the preamp chassis via 10Ohm resistor. I have used a star grounding scheme in the preamp box.
The PSU case is powder coated so I have had to wire each panel explicitly to ground. I noticed on the schematic for my PSU there is a 10Ohm resistor in parallel with a 0.1uF capacitor between 0V and ground (see picture), should I disconnect this otherwise I have 2 connections between 0V and ground? Will this make any difference?

Hello, could be a ground loop somewhere probably,
I dont know if I understood correctly the way you connected everything but let me tell you how I would do it.

1) Are you using metal standoffs to attach the 1290 pcb to case?
if you are using metal standoffs please see that one hole in the 1290 pcb is connected to ground, so that standoff should be plastic
check this

2) check if Output XLRs have Pin1 disconnected and not connected to case or circuit

3)  10Ohm resistor in parallel with a 0.1uF capacitor between 0V and Case it's correct, you should eave it that way.
Connect ground like this
- 1290 PCB 0v to PSU 0v (not to preamp case)
- PSU Main outlet ground tab (Mains Earth) to PSU Case, if its powder coated scratch the inside paint, and put a screw with a nut on the inside and connect Mains Earth wire there
- Preamp Case connects to PSU Case
- PSU pcb hole named "case" connects to PSU Case , goes to the same screw and nut of the main earth

I guess this will work,
By the way whats the transformer you are using, whats his power?
And underpowered PSU could also produce hum. In the case of this preamps I think they consume around 250mA per channel, but people advise on leaving 500mA for each channel, what makes 1Amp for both.
So if it's 24v transformer you will need a 25 VA transformer



Re: Neve 1290 build completed!!
« Reply #732 on: June 24, 2015, 04:58:39 AM »
Great, thanks for your advice.

I've used plastic standoffs so the PCB is isolated from the case, and then I've attached a wire to the PCB hole (the one linked to 0V)  and connected this to ground via a 10 Ohm resistor.

I used TRS connectors for the output and I've noticed that the Sleeve is connected to ground via the case, could this be the problem?

As for power supply, I'm using a 30VA 18V toroid so should be good for this application. I did have problems with my previous power supply, it couldn't handle running 2 boards for some reason. I replaced it and this one seems to work okay but maybe I should try one with much higher capacity and thus eliminate that potential problem.

Whoops

Re: Neve 1290 build completed!!
« Reply #733 on: June 24, 2015, 08:40:05 AM »
Great, thanks for your advice.

I've used plastic standoffs so the PCB is isolated from the case, and then I've attached a wire to the PCB hole (the one linked to 0V)  and connected this to ground via a 10 Ohm resistor.

I used TRS connectors for the output and I've noticed that the Sleeve is connected to ground via the case, could this be the problem?

As for power supply, I'm using a 30VA 18V toroid so should be good for this application. I did have problems with my previous power supply, it couldn't handle running 2 boards for some reason. I replaced it and this one seems to work okay but maybe I should try one with much higher capacity and thus eliminate that potential problem.

Connect as I described and you probably will not have more problems, if you want to use jacks on the output use plastic ones.

0V on preamp board to 0v on the PSU

Follow this:

2) check if Output XLRs have Pin1 disconnected and not connected to case or circuit

3)  10Ohm resistor in parallel with a 0.1uF capacitor between 0V and Case it's correct, you should eave it that way.
Connect ground like this
- 1290 PCB 0v to PSU 0v (not to preamp case)
- PSU Main outlet ground tab (Mains Earth) to PSU Case, if its powder coated scratch the inside paint, and put a screw with a nut on the inside and connect Mains Earth wire there
- Preamp Case connects to PSU Case
- PSU pcb hole named "case" connects to PSU Case , goes to the same screw and nut of the main earth


Whoops

Re: Neve 1290 build completed!!
« Reply #734 on: April 25, 2016, 08:24:11 PM »
Martin I have a question for you mate.

In the assembly docs for this project you connect Input transformer Pin6 (that should be connected to Chassis ground) to pin 10 (that is connected to 0v Audio reference ground).
As far as I can tell Audio Ground and Chassis Ground should only connect at one point and that is between PSU board 0V and the Case.
By connecting the Pin6 to pin10 you are making one extra connection between Audio ground and Chassis ground, if you are building 4 Mic pres, you are making 4 extra connections between those 2 grounds.

If you see the Neve schematic Chassis Ground and Audio ground are kept separated, and Pin6 is not connected to Pin10, check attached schematic.

You advise on using the JLM PSU, that connects 0V to Chassis Ground via a resistor and cap, and that seems right, but having also Pin6 on the input transformer connected to Pin10 seems to defeat the purpose.

Let me know please if what I'm saying makes sense or if I'm missing something?

Neve 1290, sample schematic attached
 

Whoops

Re: Neve 1290 build completed!!
« Reply #735 on: April 25, 2016, 08:24:41 PM »
.


 

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