8 Channel, 3U NEVE 1073 completed

[desol]

Hmm. Not sure if you want to use Cermet for rotary fader.

I'm thinkin these: http://ca.mouser.com/ProductDetail/Vishay-Sfernice/PA16NP502KAB15/?qs=sGAEpiMZZMtxdMMi52izyloICbkjSMPkjj%252byCuROyso%3d


More bread tho.

 

[muffy1975]

hey Martin and Team EZ1290,

my boards have arrived in super quick time and they look fab.

My first question with this project involves the two identical sections on the PCB. When I was ordering parts I thought there was a typo involved with the repeated list of parts. Do I need to fill in both sections if I am just building the mic amp stage?

I'm gonna look through the thread armed with my new knowledge and find out.

Thanks in advance

Michael

 

[madriaanse]

Hi Michael,

You will need to fill both sections; the BOM is correct.

M.

 

[muffy1975]

Hey there,

can I connect the drain wire via the 10r resistor to the audio output jack?
Can I do this for each channel or will this effect the resistance ie:

10r on channel one to audio output earth

10r on channel two to audio output earth

I am using metal 1/4" jacks. Will this cause a problem considering the earth is connecting to the chassis?

Michael

 

[evilcat]

Hi everyone !

I've finished my 1st unit, it works well but don't know where and how should I connect the 10r/1W resistor.
Any advice ? Thanks.

Ben A.

 

[muffy1975]

hey,

got mine going too! had a nightmare with a few loose bit of copper wire floating in the case causing shorts. Now all is good.

MAKE SURE YOUR 1U/2U CASE IS CLEAR OF DEBRIS AND THAT THE PCBS DO NOT TOUCH THE EARTH EXCEPT THROUGH THE DRAIN.

I have attached the earth  drain from the top right of the PCB ( itself is connected to the earth of the PCB ) to the earth on my XLR/JACK AUDIO OUTPUT via the 10r/1W resistor. Hope that helps!!!IS that right? Works for me!!!


XOX

GO TEAM 1290

 

[madriaanse]

Hey there,

can I connect the drain wire via the 10r resistor to the audio output jack?
Can I do this for each channel or will this effect the resistance ie:

10r on channel one to audio output earth

10r on channel two to audio output earth

I am using metal 1/4" jacks. Will this cause a problem considering the earth is connecting to the chassis?

Michael

Hi Michael and Ben,

Don't connect the 10R anywhere. Leave pin 1 entirely disconnected on the output XLRs; any properly designed AD converter or tape machine will have its own ground reference from its own power supply. Connecting the EZ1290 0V to XLR pin 1 will only give you an increased chance of ground loops. The 10R (R98 on BOM) is actually on the JLM ACDC, and when you connect the ACDC to the PSU case (& AC earth), the proper connection is made. I left R98 on the BOM just in case people use a PSU other than the ACDC. The PSU case is connected to the EZ1290 rack case through the shield (drain wire) of the 3 (or 4) conductor 18 gauge power cable that connects to the 4 pin XLR connector.

HTH,

M.

 

[evilcat]

That's what I thought ! Thanks Martin for clarifying that point. And BTW, I've already told you but again : that's an amyzing project, thank you very much ! Mine worked like a charm at the 1st time.

Ben A.

 

[madriaanse]

You're welcome Ben!

So here's something funny that happened. I've built around 32+ channels of these and never really had one that didn't fire up right away. The last one I built worked but had a problem with the second pre stage, and the voltages around TR5, TR6 were off. Went through my usual checklist and didn't find anything else out of whack. Serious head scratching followed, and nothing was solved. Came back later (frustrated) and noticed I had soldered in TR5 backwards. D'OH!!! The channel worked perfectly after I flipped it.

Humbled,  ;D

Martin

 

[frederikkofoed]

Usual Checklist?? 

Is it possible you maybe would like to share that..

I would love to see it.. in case my doesn't work the first time...

- Frederik

 

[madriaanse]

Hi Frederik,

I pretty much listed my "usual checklist" at the beginning of this thread. I start with transistor voltages, visually check components and their values against the schematic. In this case checking the transistor voltages revealed there was a problem in the TR5/TR6 area. I just didn't "see" I had mounted TR5 backwards. Which brings up another good point. If you can't figure it out, take a break, do something else, read Prodigy Pro, and then come back to it. A lot of times you'll notice or think of something you didn't before. This works for mixing as well.

HTH.

M.

 

[muffy1975]

Martin,

I'm not using the ACDC so I have to fit the 10R somewhere right?

I am using the MNATS and the 0V is the common connector on the Mnats PSU. This PSU is in the 1U rack case along with the Ez1290s/

Do I connect this common (0V) to the case via a 10R resistor?

I am using 1/4 metal jack sockets for the output and they automatically connect the earth of the jack socket to the earth of the rack case.

I used to have the 10r going from the the 0V on the EZ1290 to the jack socket earth or rack earth. i used to have a little 40-50hz hum on the output.

I have removed this, and now I'm getting full on buzz.

What shall I do?

Do any drain wires come off the EZ1290?

Thanks

Michael

 

[muffy1975]

Ok,

what I have now done is connected a 10r resistor between the MNATS common / 0V and the rack case! The MNATS PSU and the toroidal transformer are both in the 1U case along with the preamps.

Ov to earth reads 10ohms much as before when I had the resistor connected between the EZ1290 0V and the jack output.

Maybe that's cus the jack is connected to the rack case.

Is this right? Am I getting warmer?

XOX

The mic amps sound great. really rich sounding

 

[muffy1975]

Hey,

does anyone find that there is a slight low end hum on their EZ1290 when cranked to full by comparison to the Focusrite ISA 428 or any other premium grade pre?

Is this what they do or could it be the MNATS PSU?

XOX

 

[wolfgang]

does anyone find that there is a slight low end hum on their EZ1290 when cranked to full

Do you have your Mains Transformer inside the chassis with the preamps?
If yes, try turning the transformer around while you listen to the hum. I some positions hum will get louder or quieter. then fix it at the most silent position.

Or the best solution will be to make an external psu!

Hope that helps!

regards,
Wolfgang

 

[deuce42]

Like wolfgang said - is your psu external?

Rotating the power toroid can help as well but external mounting psu should be for more beneficial.

 

[madriaanse]

External PSU is always a good idea. Ask GML.

10ohm between 0V and earth is perfect, but it doesn't sound like you have the output (XLR pin 1, 1/4" TRS sleeve) disconnected, so your hum problem could also be a ground loop. 0V should not connect to the output - anywhere. Older TT patchbays used to do this automatically for you anyways. On my units there is no noticeable hum - it is below the noisefloor... that is as long as I use good mic cables and keep away from AC.

M.

 

[statzern]

Hey guys, I am about to finish the first channel of my dual channel box. Unfortunately, my planning was not so great in my placement of the trannys. I am afraid that my setup may cause some issues. The input and output lines have to cross as I have it set up (see attached file - red is "pre-preamp" and green is "post-preamp"). Does anyone forsee this being a real problem?

Thanks in advance!

Nick  ;D

 

[Whoops]

I would change the Transformer placements this way:

(pic attached)

 

[madriaanse]

Yes, Whoops nailed it! You probably want the total cable length between VTB9045 and EZ1290 PCB to be about 9-10".

M.