8 Channel, 3U NEVE 1073 completed

Hi madriaanse

for the 47ohm resistor, the board says 1w, but the part number in your BOM is a 1/2w resistor.

Is the part in your BOM (and in my possession) OK to use, or shall I get a 1w version?

Thanks a lot, boards are great quality... a pleasure to work with!

Jake

Hi Jake,

1/2W from the BOM works just fine.

Best,

M.

Sorry if this maybe has been asked, but what PSU is everyone using to power 8 channels?? I don't mean the trafo, I mean the board/regulators. For example, if you use a LM7824, it's good for 1 amp, right? This would give you .125 Amps per channel, which is over the original neve spec, but way below what most people are calculating their trafos for.  So, I guess I am wondering if we are potentially bottlenecking these things if we calculate our trafos to put out 0.5 Amps per channel yet use a PSU that is capable of much less? Is there a 3-4A version of the 7824?

I asked Joe at JLM. He told me the 1290 uses about 120ma ea...but have a large surge on power up.
Not sure how much it'll use when pushing low impedances.

I'm gonna use 2 x ACDC to power my eight....giving 375ma per channel. Should be good i figure, unless someone here suggests otherwise.
Cheers.

So to power 2 channels you use one ACDC, and that's tried and true. It's probably best to use 4 of them to power an 8 channel unit (Like Martin did)! At high gain (if you're tracking drums, for example) they're going to use more power and the pre's might not get enough. if they don't, they crap out and distort. That's one reason why it's best to "over-build" your power supply.

danjpiscina said:

So to power 2 channels you use one ACDC, and that's tried and true. It's probably best to use 4 of them to power an 8 channel unit (Like Martin did)! At high gain (if you're tracking drums, for example) they're going to use more power and the pre's might not get enough. if they don't, they crap out and distort. That's one reason why it's best to "over-build" your power supply.

Click to expand...

That's what I thought.. I was hoping there was a higher current regulator available. I googled a bit after I posted and found this among other links:
http://ourworld.compuserve.com/homepages/Bill_Bowden/page12.htm

The second schemo uses a pnp transistor with an LM317 to do a 12V, 4.3A supply. Is it just a matter of swapping out the voltage setting resistors to get 24V (as well as using an appropriate trafo)??

ALSO, I just saw that the switches I got from someone here are non-shorting  :  .... Will this pose a serious problem or will wiring a resistor from each pole to ground take care of the pops? If so, how do I figure out the value?

thanks!

mitsos said:

The second schemo uses a pnp transistor with an LM317 to do a 12V, 4.3A supply. Is it just a matter of swapping out the voltage setting resistors to get 24V (as well as using an appropriate trafo)??

ALSO, I just saw that the switches I got from someone here are non-shorting  :  .... Will this pose a serious problem or will wiring a resistor from each pole to ground take care of the pops? If so, how do I figure out the value?

thanks!

Click to expand...

Good questions. Martin? Help!  :-\

maybe I'm confused on the switch, cuz the part number matches the bom. I had always just assumed it was shorting. Good thing I got these as a package deal, otherwise I would have bought the wrong switches.....  doh!

Does anyone know of any substitutes for the toroidal transformer?  Digi-key has it on *cough* 20 week back order.  All help is appreciated.

Thanks-
dave

call John at Antek for toroids. They also sell on Ebay but it's a couple bucks cheaper direct.

Hello everyone,

i am very happy to say that i finished building 2 channels 1290 and it sounds absolutely fantastic!! Thanks martin!

i just have one issue on 1 channel:
when i get to high gain (it should be around 50dB and more) i have no sound. when i tried it first it was going on and off, but now i have no sound at all. at lower gain it sounds fine and great.
I even havent set the bias yet.

any help is much appreciated!

thanks

guidoz: Check for cold solder joint on the last switch terminal.

Jim

Check the resistor values around the gain switch setting that produces no sound - if the resistance value is too large, it will also block out all the gain settings after the one you mention as they run in a chain.

thanks!
will check both options.

how can i check the resistance value? between which points on the PCB?

Read resistor values on circuit its almost impossible.
you said you have 2 channels? check 1 vs the other...
If it worked before maybe as Bluzzi said cold joint!

The resistors are connected to switch. So just make sure you are not in the position of the resistor you want to measure and it will be out of the circuit. If you can read the color code then look up value that way. But wait, you said you had 2 channels. So 1 channel works 100% right? Then compare color codes to make sure values are same, then measure (with switch in position 1 lets say) and compare.

If above does not yield any answer check for cold joint by either de-soldering and then re-soldering. Also make sure you do not have any solder jumping to an adjacent point. The gaps in between the Grayhill are quite tight and its more possible to solder badly there than anywhere else on the board.

Jim

Hi All,

I am very nearly done with my 2 channel 1073/1290, i do have a few small issues that i would love some help with!

Firstly the ACDC PSU from JLM.
How do i populate the board for 230v/240v UK power, and how do i connect the Toroidal transformer from Digi key??
Also what voltages do i need to measure from the output of it?

Secondly i have designed a front panel using front panel express which i am happy with but i'm not sure how to design the rear panel and rack chassis to integrate with the front?? I spoke to the guys at FPE, they told me to design the rear just like the front, which im ok with i can do that just about. But how am i to know what rack chassis to buy to fit the front and rear panels from FPE???

The last thing is in the assembly guide it says to use 6/32 bolts to attach the heat sink and transistor to the board, what is 6/32 in mm is that and m4 bolt/nut etc?? Will these also fit the 4 holes for the main pcb to fix to the chassis??

Would appreciate any input,
Regards
Sam

Hello!

for the AC/DC: look at the JLM-Website. As you need only +24V and +48V you can leave the -V rail parts out!

And you should adjust it like said before to+24 and +48 for phantom.

I dont knw the digikey transformer. Is the primary 2x115 or 1x 230? doy you have dual secondaries?


FPE: I think you shhould buy a rack before you order at FPE. You can measure every hole to be sure your panels will fit in the end!


Heatsink screws are 4mm i think and the PCB mounting screws are 3mm.

In this minutes i am finishing my third 1290! Measured all voltages and they are fine!!!!!
Now i only need an osci to bias this great pre!!!

Many thanks to madrianse for this great sounding and so well documentet project!!!!!!!!!!

all the best,
Wolfgang

nflame13 said:

Firstly the ACDC PSU from JLM.
How do i populate the board for 230v/240v UK power, and how do i connect the Toroidal transformer from Digi key??
Also what voltages do i need to measure from the output of it?

Click to expand...

Please see: http://musiciansgig.com/ez1290/220V_ACDC.pdf
Be sure to adjust for correct voltage **before** you connect to the EZ1290

Secondly i have designed a front panel using front panel express which i am happy with but i'm not sure how to design the rear panel and rack chassis to integrate with the front?? I spoke to the guys at FPE, they told me to design the rear just like the front, which im ok with i can do that just about. But how am i to know what rack chassis to buy to fit the front and rear panels from FPE???

Click to expand...

You're putting the cart before the horse - you'll want to buy the case first. Then design a panel for it and print a cardboard, 1:1 scale mockup to see how it all fits before ordering your panel.

The last thing is in the assembly guide it says to use 6/32 bolts to attach the heat sink and transistor to the board, what is 6/32 in mm is that and m4 bolt/nut etc?? Will these also fit the 4 holes for the main pcb to fix to the chassis??

Click to expand...

6/32 has a 3.5mm major diameter.
M3 will definitely fit, M4 may or may not.

Hope this helps.

M.

ahh ok thanks guys that helps alot! ;D

Just one question for the acdc 220 v wiring diagram, what pins are yellow and violet connected to on the IEC connector. Basically which colour corresponds to live, neutral, earth etc?

Regards
sam