8 Channel, 3U NEVE 1073 completed

[TDRS]

OK, not really surprised, it's not the switch. Good switch swap results in the same behavior. It would have been an easy fix but no such luck. Back to the drawing board. I'll have to comb over one of these boards ( for the hundredth time) and see what is the common denominator that sets these apart from the 6 working modules I have. Knowing it's not the switch will help keep my mind on the task. I did start sourcing parts on ebay for this batch, Panasonic Tants and the poly's. Those all check out though and both BA183's seem to be working fine if I insert tones. It sure seems like it must be R22,11,21,20,29 or 30. It acts like I have the wrong values but they check out or solder bridges that route through the wrong resistors but I keep thinking how could a mistake like that be repeated 3 times and maybe more as I check out the rest of my 12 boards? It's got to be something staring me in the face, theres just not that much too these boards.

 

[TDRS]

OK,  yes…stupid human error. I found it.  Jeez.  I checked it over and over and my brain saw what it thought was right over and over.  For some reason it not being the switch un-clouded my view and I saw it.  Not only that it's a mistake I had read another builder had made here in this thread. It was R8. I had put a 1K5 in there instead of 15K. Not only that I did it several times on several boards. I feel like an idiot but a happy idiot. Thanks for all your help. It's much appreciated.

 

[Whoops]

OK,  yes…stupid human error. I found it.  Jeez.  I checked it over and over and my brain saw what it thought was right over and over.  For some reason it not being the switch un-clouded my view and I saw it.  Not only that it's a mistake I had read another builder had made here in this thread. It was R8. I had put a 1K5 in there instead of 15K. Not only that I did it several times on several boards. I feel like an idiot but a happy idiot. Thanks for all your help. It's much appreciated.

Thats a classic mistake, don't worry it happened already to all of us at some point.

Happy that it's sorted

 

[TDRS]

Thanks Whoops and thanks for your help!

 

[lestatdog]

This seems like a great project after reading a lot of the 117 pages, is there any chance someone has already made a pcb for the 500 series. Looks like it would be a great fit.

 

[Whoops]

This seems like a great project after reading a lot of the 117 pages, is there any chance someone has already made a pcb for the 500 series. Looks like it would be a great fit.

yes, theres other similar projects for the 500 format in the White Market.
Don classics NV73 and Sound Skulptor MP573 come to my mind

http://groupdiy.com/index.php?topic=41147.0

http://groupdiy.com/index.php?topic=33492.0

 

[MountCyanide]

Hey folks-
I'm about to troubleshoot my ez1290 which has been working great for 2 years but just developed a problem.
If I unplug the output and leave the mic plugged into the input, the mic capsule starts emitting a quick screech at a constant interval. It's loud. I measured this spike and found it to be 3VAC.
Ground problem?
I may have damaged my AEA ribbon. 

FIXED. It was the 2N3055. Swapped for another and all is fine now. And AEA quickly fixed my R92.

 

[joakimkarlthomas]

Is it possible to buy the power supply instead of building it?

Like this one for example:

http://www.sealevel.com/store/tr108-100-240vac-to-24vdc-at-2-7a-desktop-power-supply-requires-power-cord.html

 

[Whoops]

Is it possible to buy the power supply instead of building it?

Like this one for example:

http://www.sealevel.com/store/tr108-100-240vac-to-24vdc-at-2-7a-desktop-power-supply-requires-power-cord.html

Better to build a Linear PSU instead of a cheap switching PSU, you also need a 48v rail besides the 24v one.

 

[rp3703]

Anybody know the pad resistor values. I know it has been suggested to just buy a JLM Go Between but there's no reason. All the necessary items can be housed on the switches themselves. Anyhow, I just need to know what the resistor values are. It may be posted somewhere in this thread but I don't have time to read 107 pages. By the way, as a warning to anyone else who comes across this, I bought the MNAT's Variable + Phantom PSU from Hairball to power two EZ1290's. Even though I have yet to fire it up, that PCB is poorly designed. The solder pads are so tiny that is next to impossible to get solder to flow onto them plus the PCB is one sided so the holes are not copper coated. This means that too much heat causes pads to lift. For someone who references some of Douglas Self's projects, he should have read some of his design rules. Just warning any one els who considers using this PSU.

 

[Whoops]

Anybody know the pad resistor values. I know it has been suggested to just buy a JLM Go Between but there's no reason. All the necessary items can be housed on the switches themselves. Anyhow, I just need to know what the resistor values are. It may be posted somewhere in this thread but I don't have time to read 107 pages. By the way, as a warning to anyone else who comes across this, I bought the MNAT's Variable + Phantom PSU from Hairball to power two EZ1290's. Even though I have yet to fire it up, that PCB is poorly designed. The solder pads are so tiny that is next to impossible to get solder to flow onto them plus the PCB is one sided so the holes are not copper coated. This means that too much heat causes pads to lift. For someone who references some of Douglas Self's projects, he should have read some of his design rules. Just warning any one els who considers using this PSU.

Hello,
whats rating on your soldering iron?
I think you are using a hotter soldering iron than you should.
Just for reference I use a 12watt soldering iron with thin tip for most of the pcb's soldering. Thats what I would advise.

As for the PAD, a lot of different resistor values can be used, depends on how much attenuation you want.
If you want to achieve the same attenuation as the JLM Go Between the easiest way is to search for the Go Between schematic, then you will have the value for the 3 resistors. Easy Enough

For Reference on PADs check this website, it has probably everything you need to know:

http://www.uneeda-audio.com/pads/

 

[rp3703]

Thanks, found the schematic. Don't know why I had trouble finding it before. Regarding the PSU, it may be that my iron is a little too hot but a good designer would account for that. The solder pads for the individual components are not much larger than the actual hole. The holes are not copper lined. There could have been pads on both sides of the board to make connections stronger and less likely to cause pad lift. By contrast, the EZ1290 went together no problem. I'm just warning anyone else who may be thinking about using the MNAT's PSU. Be careful.

 

[Whoops]

The holes are not copper lined. There could have been pads on both sides of the board to make connections stronger and less likely to cause pad lift. By contrast, the EZ1290 went together no problem.

The MNAT's PCB is a single layer PCB.
Single layer - single pads

It's an inexpensive pcb, it costs $15 and not $50

if you want something better buy the JLM 3 Rail PSU:
http://www.jlmaudio.com/shop/ac/dc-kit.html

 

[joakimkarlthomas]

i'm ordering components and 25v 82uf electrolytic cap isn't available. Can I use 50v 82uf instead?

 

[MicDaddy]

Should work if it will fit with the larger voltage rating.

 

[XAXAU]

Hi guys I just ordered a pair of EZ1290´s and my plan is to make a 8:2 summing unit with 8x Carnhill VTB9046 in the inputs plus having the usual 2x VTB9045 & 2x VTB9049.

I was wondering if anyone has tested the mu-metal versions of the 9045´s & 9046´s. Was planning on putting the JLM Kraftwerk PSU inside the case but maybe that´s asking for trouble?

Love this thread!  ;D


Cheerio

 

[Whoops]

Hi guys I just ordered a pair of EZ1290´s and my plan is to make a 8:2 summing unit with 8x Carnhill VTB9046 in the inputs plus having the usual 2x VTB9045 & 2x VTB9049.

I was wondering if anyone has tested the mu-metal versions of the 9045´s & 9046´s. Was planning on putting the JLM Kraftwerk PSU inside the case but maybe that´s asking for trouble?

Love this thread!  ;D


Cheerio

Do you have a rough diagram or sketch of what you want to do?

I think you still need to study better your goals and how to achieve them.
The ez1290 is a Mic preamp capable of 85 dbs of Gain, thats much more than what you need for a summing mixer.

Also if you want to do passive summing with Neve makeup gain I guess you wouldnt use the line input transformers, just a passive resistor network that will feed a Neve amp capable of providing 40 to 50 db's  of gain, you can do that with 2x 1272 or with 2x BA283 cards.

if I got it wrong just let us know, but it seems to me that you still have to study a litle bit better the design you want to accomplish

 

[XAXAU]

Do you have a rough diagram or sketch of what you want to do?

I think you still need to study better your goals and how to achieve them.
The ez1290 is a Mic preamp capable of 85 dbs of Gain, thats much more than what you need for a summing mixer.

Also if you want to do passive summing with Neve makeup gain I guess you wouldnt use the line input transformers, just a passive resistor network that will feed a Neve amp capable of providing 40 to 50 db's  of gain, you can do that with 2x 1272 or with 2x BA283 cards.

if I got it wrong just let us know, but it seems to me that you still have to study a litle bit better the design you want to accomplish

Hey Whoops!

I got a lot of help from Ian (Ruffrecords) because I´m a newb and he´s a very nice knowledgeable guy and the plan right now is this:

> Neve 8:2 summing mixer with 8x Carnhill VTB9046 input trafos (10K:600)
> Balanced passive summing network with 226 ohm R´s (loads input trafos with 603 ohms) Bus impedance: 113 ohms Attenuation: -25dB (Trafo -13dB & summing network -12dB)
> 4PDT changeover switch which toggles between the summing network and the 2x EZ1290 micpres.
> 2x EZ1290 micpres with JLM Go Betweens + 2x JLM FET DI´s.
> JLM VU2 Stereo VU Buffer Kit with 2x Sifam AL20SQ-Retro VU meters.
> 4PDT changeover switch which toggles the VU between input (at VTB9045 so it reads either the summing network or micpres depending  that other switch) and output.
> Might want to split the output and feed AD and monitors separately through an Elma 47 stereo stepped attenuator with manual matching of the resistors. It depends if I get a AD/DA converter with sophisticated routing & monitoring or not.
> Internal PSU but if it doesn´t work I´ll make an external one. No Biggie.
> Maybe  rotary stepped trimmers or attenuators after all three gain stages or both. Will have to test the sound and distortion to see what my ears like.
> I´m 99% ITB except for my Moog Voyager so I´m looking for analog summing and micpres with lots of colour!

That´s about it. I hope I was clear enough and that my ideas will work. Thanks! 

 

[Whoops]

It's great that you got help from Ian.
I still don't understand some points about your design, but Ian is much more knowledgeable than me.

As for the PSU, you can put the PSU inside the case and use the case as an heatsink for the regulators.
The problem will be if you put the toroid transformer also inside the case, even with shielded audio transformers the toroid will induce hum in the circuit.

So my advise would be to just do an external case for PSU+Power transformer , or leave the PSU inside and do an external case for the Power Transformer only.

 

[XAXAU]

I still don't understand some points about your design.

Which part?

As for the PSU, you can put the PSU inside the case and use the case as an heatsink for the regulators.
The problem will be if you put the toroid transformer also inside the case, even with shielded audio transformers the toroid will induce hum in the circuit.

So my advise would be to just do an external case for PSU+Power transformer , or leave the PSU inside and do an external case for the Power Transformer only.

Been looking at mu metal cans but the´re like €100 a pop. Stainless steel, if thick enough, will help. I´ve seen that 6mm ferritic steel will work.

But I guess I can just build a nice floorbox PSU instead!