8 Channel, 3U NEVE 1073 completed

[madriaanse]

I swapped mpsa18' for bc184' on one board...works like a charm... 

No kidding!? I'm excited you got it figured out; it's the best feeling when persistent troubleshooting pays off.

I'm puzzled however about those MPSA18's. They should've worked and looked like they were oriented correctly (backwards) on the board.

M.

 

[remsouille]

That is indeed a great feeling, though I really don't understand what the problem was... Anyway thank's a lot to you all for the help, I'll be using all of them soon on an acoustic session, I'll post the songs ASAP!!!

 

[CemD]

excellent project.
I'm a newbie.
I'm also trying to collect EZ1290.
I have a quick question.
The PCB is labeled C13 150uF 16V.
I am not available С13 150uF 16V.
Can I replace it on a standard 100uF or 220uF.

 

[madriaanse]

excellent project.
I'm a newbie.
I'm also trying to collect EZ1290.
I have a quick question.
The PCB is labeled C13 150uF 16V.
I am not available С13 150uF 16V.
Can I replace it on a standard 100uF or 220uF.

I'm not sure why you would do that. Here's the Digikey part# to use: 4018PHCT-ND.

M.

 

[desol]

The only cap you should substitute(or part for that matter) are the 80uf cap's in the output section...with available BC 100uf caps.
Everything else should be available one way or another.

 

[CemD]

The only cap you should substitute(or part for that matter) are the 80uf cap's in the output section...with available BC 100uf caps.
Everything else should be available one way or another.

Yes, I know about the replacement 80uF to 100uF.
I have all the parts.
I do not have 150uF. Only this part is not. But there is 100uF and 220uF.
So I want to make a change. If it is possible.

 

[desol]

Edited:

http://www.digikey.ca/product-detail/en/MAL202135151E3/4018PHCT-ND/263242

I used as many BC caps as I could source for my 1290's. Just to keep it lookin 'real...

 

[dmp]

I do not have 150uF.

If you don't want to buy the 150uf part, I think you can try a change and report back on how it works.
It just acts as a bypass cap for R15 and it looks like the original Neve value was 125uf. You probably won't notice a difference if you use 100uf or 220uf, but 220uf would probably be better.

 

[junkface]

Just finishing up sourcing the BOM for 4 channels. I'm wondering about the quantities I'll need for the PSU(s). Could I get away with one PSU (housing, JLM AC/DC, power transformer, etc) to power the 4 channels as it's spec'd out?

 

[desol]

Just finishing up sourcing the BOM for 4 channels. I'm wondering about the quantities I'll need for the PSU(s). Could I get away with one PSU (housing, JLM AC/DC, power transformer, etc) to power the 4 channels as it's spec'd out?

Right here man. Joe designed this unit specifically for 4 channels of Neve (or other 24v modules).

48v, 0v and 24v.

http://www.jlmaudio.com/shop/index.php?_a=viewProd&productId=145

 

[CemD]

If you don't want to buy the 150uf part, I think you can try a change and report back on how it works.
It just acts as a bypass cap for R15 and it looks like the original Neve value was 125uf. You probably won't notice a difference if you use 100uf or 220uf, but 220uf would probably be better.

I is not economically profitable to buy 150uF. Very expensive delivery.
I decided to replace 220uf.
But I will try to put in parallel 100uf + 47uf.
I think it will work.

 

[junkface]

Right here man. Joe designed this unit specifically for 4 channels of Neve (or other 24v modules).

Woot! Thanks desol. Really looking forward to digging into this project.

 

[digistu]

Hi,

After having played with my 4 channel ez1290 for a few weeks, I've picked up on a couple of problems.  Namely that three of the four channels exhibit what sounds like radio interference at specific gain stages (different points on each of the channels).  Channel one does it too when the lid of my case is unattached, but is fine when the lid's on - if I wave my hands around in the general area of the boards the frequency and intensity changes.  Sometimes touching the bodies of the Grayhills can make it better/worse. 

To my (pretty much) amateur mind this suggests problems with shielding or grounding, but does anyone have any words of advice they can offer to assist my troubleshooting?  A picture's attached to give a general idea of my case layout - I can provide more detailed pics if you think it'll help.

Things I've done/tried/suspected:

Used shielded mic cable on all XLR/transformer connections.

My power supply (a five fish 2448) is supplying 24 and 48V on the nose.  Resistance between case and 0V (of the power supply) is 10ohms, however once plugged into the preamps (via 4 pin XLR) resistance between preamp case and 0V (on the 1290 boards) is 100ohms - is this to be expected once all the components are in the path?  Or is something awry with my grounding?  Cases are connected via pin 2 of the XLR as per the assembly instructions.

Actual operating voltage drops to 23.7V when measured at the boards.  I've wired the 0V and 24V connections between boards - would it be better to star them individually from the PSU connector?

Could the wiring of the phantom power be causing problems?  There are a couple of points where the phantom wires cross shielded signal wires, and the switches are close(ish) to the points on the boards where the input transformers connect.  I have tried disconnecting the 48V cable, but it didn't make any difference.

All transistor voltages check out ok.

I've checked continuity between the network of resistors around the switch against the schematic, and everything seems as it should.

Any advice is appreciated.

Thanks!

 

[madriaanse]

Hi Digistu,

My power supply (a five fish 2448) is supplying 24 and 48V on the nose.  Resistance between case and 0V (of the power supply) is 10ohms, however once plugged into the preamps (via 4 pin XLR) resistance between preamp case and 0V (on the 1290 boards) is 100ohms - is this to be expected once all the components are in the path?  Or is something awry with my grounding?  Cases are connected via pin 2 of the XLR as per the assembly instructions.

That doesn't sound right. It should stay at 10 ohms at all times.

Actual operating voltage drops to 23.7V when measured at the boards.  I've wired the 0V and 24V connections between boards - would it be better to star them individually from the PSU connector?

Yes, definitely.

Could the wiring of the phantom power be causing problems?  There are a couple of points where the phantom wires cross shielded signal wires, and the switches are close(ish) to the points on the boards where the input transformers connect.  I have tried disconnecting the 48V cable, but it didn't make any difference.

Not likely.

The preamp case is earthed properly, correct? (It looks like it from the picture). There should be 0 ohms between preamp case, PSU case and wall outlet earth. You have a bunch of wire loops on the output transformers and the wire leads for LO1166's RC network are rather long too. Make all these wires as short as is physically possible to avoid making antennas. In fact, make all wires as short as possible.

 

[digistu]

My power supply (a five fish 2448) is supplying 24 and 48V on the nose.  Resistance between case and 0V (of the power supply) is 10ohms, however once plugged into the preamps (via 4 pin XLR) resistance between preamp case and 0V (on the 1290 boards) is 100ohms - is this to be expected once all the components are in the path?  Or is something awry with my grounding?  Cases are connected via pin 2 of the XLR as per the assembly instructions.

That doesn't sound right. It should stay at 10 ohms at all times.

I was being stupid here and measuring the resistance with the preamps connected to the power supply.  With the PSU turned off I have 10ohms between case and 0V at all times.

[quote author=madriaanse]

Actual operating voltage drops to 23.7V when measured at the boards.  I've wired the 0V and 24V connections between boards - would it be better to star them individually from the PSU connector?

Yes, definitely.

The preamp case is earthed properly, correct? (It looks like it from the picture). There should be 0 ohms between preamp case, PSU case and wall outlet earth. You have a bunch of wire loops on the output transformers and the wire leads for LO1166's RC network are rather long too. Make all these wires as short as is physically possible to avoid making antennas. In fact, make all wires as short as possible.
[/quote]

Yes, I think the preamp case is earthed properly - pin 2 of the four pin XLR is connected to the case, which in turn connects to the PSU case, which in turn is linked to the wall outlet earth. 

I'll try rearranging the +24V and 0V wiring and making the other wires shorter and see where that gets me. 

Will report back!  Thanks for your help.

 

[bertt]

Hi everyone,

i'm new in the DIY-world. I am searching the components to fill 4 of Martin's EZ1290 PCB's.
Where can I find alternative for :

Pre-stage C9 Capacitor Polystyrene 100p (mouser #23PS110 not on stock).

Is Multilayer Ceramic Capacitors SL155A101FAB or 80-C315C101F5G at Mouser an alternative ?
http://nl.mouser.com/ProductDetail/AVX/SL155A101FAB/?qs=%2fha2pyFaduj524wUVNUtut7lYDs2KLFx8oiHxlfGv7hVktdSdsEH3w%3d%3d
or
http://nl.mouser.com/ProductDetail/Kemet/C315C101F5G5TA/?qs=sGAEpiMZZMt3KoXD5rJ2Nw7wLkVkYXKYCDnk%252bTZELb4%3d


C9 Capacitor Polyester Film .01uF 400V (mouser #75-225P400V0.01 not on stock).
Is Film Capacitors 400Volts 10000pF ORANGE DROP an alternative?
http://nl.mouser.com/ProductDetail/Cornell-Dubilier/225P10394XD3/?qs=%2fha2pyFadugQV5RJRvjRYqHNU1UOChVIh8uouuBZ4Z4PcR%252b%2fxBjXug%3d%3d

greetings,

Bert

 

[North]

Weird problem. Anytime I try to get to anything on JLM Audio's website, I get this:

-"Forbidden You don't have permission to access /shop/index.php on this server."
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.:

Anyone else get this?

 

[fred]

Just to let you know that I built one channel to try out MPSA18 mounted backwards but no luck. I had no sound, so I replaced the MPSA18 with the BC184 bought on Ebay and it works... Don't know why...

Anyway, thanks Martin these babies are great preamps!!

 

[3nity]

Just to let you know that I built one channel to try out MPSA18 mounted backwards but no luck. I had no sound, so I replaced the MPSA18 with the BC184 bought on Ebay and it works... Don't know why...

Anyway, thanks Marti

Weird, build 2 x 1272s with MPSA18 as well as my 2 x EZ1084s.
They worked wonders!

 

[tzman]

Weird problem. Anytime I try to get to anything on JLM Audio's website, I get this:

-"Forbidden You don't have permission to access /shop/index.php on this server."
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.:

Anyone else get this?

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