8 Channel, 3U NEVE 1073 completed

[desol]

Hmm. If you run a powerstation @ 2x25v, full rectification...you should be able to run the api's on one rail and the Neve's on the other. 1.5 amps per side. Transformer will be pricey for this setup though..i think. Also, you have to consider your heatsink setup for all 5 regulators.

 

[herrmann]

Ok, I have a 50VA 2x24 transformer, I think it should be enough for 2x1290 and 2x312. The 312 run on +/-24 and +12 for the relays. Maybe I could power the relays with a inverted -12V ?
+48
+24 -> 1290
+24 -> 312
-24 -> 312
-12 -> 312 relays
???

 

[mitsos]

Make sure the opamps you use in the 312 can handle +/- 24V. 

 

[madriaanse]

Yeah I don't know about putting +24V on 312's. Don't those usually get +/-18V?

m.

 

[funkymonksf]

I have hooked everything in my dual channel 1290. I am not getting any signal out of my pres. Only a sizzling sound. I resoldered most of the joints, went through all my wiring. Checked my voltages. Any everything should be working, but it is not. Is there any else I should try or look for? I am now considering buying new PCBS and doing it all over again. .

 

[madriaanse]

Hi Funkymonksf,

How are your voltages? http://s3.amazonaws.com/EZ1290/transistor_voltages.pdf

M.

 

[funkymonksf]

They are reading within the limits I believe. If they are off what do you believe is the cause?

Thanks again for such a speedy reply!

Brice

 

[gerardmanvuca]

yes, what YLab said. It could also be a gain staging problem. How's the mic pre perform with units that have line level XLR inputs?

M.

i did some tests with diferent xlr leads and the problem is defo not the xlr leads. i should mention that i built a stereo pre and the level problem is identical in both channels. I also have 2 jlm fet di modules installed in both channels (i haven't taken them out and tested the pres, maybe i should?).  i also havent tested the pre on line level xlr AD inputs but will do as soon as i can get into my mates studio.   So is it the case that the ez1290 should clip the soundcard evan at line level/-10dB, before the pre itself clips?   cus mine is clipping way before the soundcard(at -10dB).

heres a pic if it mite help in any way
http://i282.photobucket.com/albums/kk280/iamproof/IMG_0657.jpg

 

[snipsnip]

Did you ground the PCB to the chassis with 10ohm resistor.

Jake

 

[YLab]

i did some tests with diferent xlr leads and the problem is defo not the xlr leads. i should mention that i built a stereo pre and the level problem is identical in both channels. I also have 2 jlm fet di modules installed in both channels (i haven't taken them out and tested the pres, maybe i should?).  i also havent tested the pre on line level xlr AD inputs but will do as soon as i can get into my mates studio.  So is it the case that the ez1290 should clip the soundcard evan at line level/-10dB, before the pre itself clips?  cus mine is clipping way before the soundcard(at -10dB).

I would do a quick test without the jlm just to be sure. Should be pretty easy with those screw terminals. And dont forget that your sound card is more sensible at -10dbv than +4dbu (can take more input at +4) And even at +4,, the preamp should not clip before the soundcard!
Hub

 

[madriaanse]

yes, what YLab said. It could also be a gain staging problem. How's the mic pre perform with units that have line level XLR inputs?

M.

i did some tests with diferent xlr leads and the problem is defo not the xlr leads. i should mention that i built a stereo pre and the level problem is identical in both channels. I also have 2 jlm fet di modules installed in both channels (i haven't taken them out and tested the pres, maybe i should?).  i also havent tested the pre on line level xlr AD inputs but will do as soon as i can get into my mates studio.   So is it the case that the ez1290 should clip the soundcard evan at line level/-10dB, before the pre itself clips?   cus mine is clipping way before the soundcard(at -10dB).

heres a pic if it mite help in any way
http://i282.photobucket.com/albums/kk280/iamproof/IMG_0657.jpg

Definitely give it a try without the DI's. The soundcards should clip waaay before the EZ1290 at either +4 or -10. Do you have your output transformer(s) wired backwards (out of phase) by any chance? Also have a look at the FAQ at the beginning of this thread. Voltages ok? Did you bias the mic pre?

M.

 

[madriaanse]

They are reading within the limits I believe. If they are off what do you believe is the cause?

Thanks again for such a speedy reply!

Brice

Hi Brice,

It could be a number of things, but usually is caused by cold solders or wrong resistor values.

HTH,

M.

 

[funkymonksf]

AHHH!!!! So it turns out that the problem was a grounding issue. I had an inkling  as much, but just could figure where it was or what was missing. I decided to solder hookup wire from the hole between input trans and power holes and connect it to the case. SUCCESS! These things sound great! I still need to Bias them and switch the48v switches around! Thanks Martin, you are a bad ass!


-Brice

 

[muffy1975]

team,

i can't read the BOM on my computer! Has anyone got the new BOM as a PDF or something that my MAC can read. It will not read xls.

Thanks for any help. This is my first post for this project

Regards

Michael

 

[Carlos Lima]

Download Neooffice from www.neooffice.org

Free (!), both PowerPC/Intel versions and reads and writes .xls, .doc, etc...

Carlos Lima

 

[madriaanse]

Download Neooffice from www.neooffice.org

Free (!), both PowerPC/Intel versions and reads and writes .xls, .doc, etc...

Carlos Lima

Yep, there's also http://www.openoffice.org/ (and really no longer any reason to buy any microsoft office products

M.

 

[madriaanse]

AHHH!!!! So it turns out that the problem was a grounding issue. I had an inkling  as much, but just could figure where it was or what was missing. I decided to solder hookup wire from the hole between input trans and power holes and connect it to the case. SUCCESS! These things sound great! I still need to Bias them and switch the48v switches around! Thanks Martin, you are a bad ass!


-Brice

Nice work Brice. So let me get this straight, you hooked 0V to case and that made it work? That doesn't sound quite right, maybe I'm misunderstanding...

M.

 

[funkymonksf]

Martin,

On the latest PCB there's a hole between the power holes and input trans holes. It's not labeled. I randomly decided to ground the PCB using it and attaching to the case. It seemed to do the trick. It now works with little noise. Now I am trying to figure out how I am going to Bias this thing without an Oscilloscope. Any recommendations?

-Brice

 

[madriaanse]

Hi Brice,

That's interesting. There's supposed to be 10hm resistance between case and 0V (they're not supposed to be connected). I wonder why doing this made yours work. Is your PSU connected correctly (pls see updated assembly guide: http://s3.amazonaws.com/EZ1290/assembly3.pdf).

You can (kinda) get away with not biasing using a scope by adjusting the 5k trimpot on the EZ1290 board until TR3 collector (the casing of 2N3055) measures 22.6 volts to ground/0V. This is assuming you have the ACDC rail adjusted to a nearly perfect +24.0V

M.

 

[adrian]

hello!
i'm finishing my 4 1290 unit, i'm very exited to test it!
i know Madriaanse doesn't like so much the idea to put a trimmer but i'd like to  test it, do you think this pot would be good enough?

http://radiospares-fr.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=169398&x=0&y=0

thanks!