8 Channel, 3U NEVE 1073 completed

[craigmorris74]

ooh, Sta-Level!

 

[madriaanse]

Hi Adam,

Thanks for your interest in this project! The PCB's are $25 ea. pls email me at 1290preamp [at] gmail.com for shipping details etc.

All the best,

Martin

PS I was able to work out the pricing problem with the manufacturer, and the new V2.0 boards (no need to cut pins on PCB-mount rotary) are scheduled to be here on friday. I am going to be testing them for a while to make sure they're 100% accurate like the V1.0's were.

 

[mhartung]

Nice work!

How did you do the white writing on the front panel? Silkscreen??

thanks

Mike

 

[madriaanse]

I've had some problems with my email account (spam filter set too aggressively), and just found out a bunch of people's emails never got to me. If you emailed me re: PCB's and I haven't responded, please email me again. Sorry

The panel is CNC engraved/machined with white in-filling.

All the best,

M.

 

[cjs2k]

Hey Martin, I have a question regarding the phantom power. Your diagram has 6k81 resistors and the schematic has 6k8, can I use 6k8s? Is this configuration usable in any type circuit (312)? Thanks.

 

[madriaanse]

Hello cjs2k,

The precise value of these resistors is not that important (within reason). What IS important is that they are matched in value as closely as possible. So if you need only four 6K8 resistors, I'd order 20 and use an ohm meter to pick two pairs that have nearly identical values.

This wiring is used for virtually all phantom powering, but some setups need what's called "ramped 48v" - a slow increase in voltage up to 48V when it's turned on. This involves adding a few caps and resistors. 1272/1290/1073 preamps don't require this; see Geoff Tanner's response here: http://www.auroraaudio.net/dcforum/DCForumID1/454.html

Take care,

M.

 

[cjs2k]

Great info, Thanks alot!

 

[madriaanse]

More V2.0 boards arrived and tested out great! I have a few extras to sell; pls send an email to: 1290preamp [at] gmail.com if you're interested.

Take care,

M.

 

[conleycd]

If people are looking at doing this project (1 or 2 channels) a simple and cheap way to do the power supply would be to order a JLM Zener splitter and their 48 volt power supply. It would be under $50 US - well I guess you need shipping on top which is usually pretty cheap from JLM. That way you could actually have the power supply inside and just have an external 48 volt adapter.

Christopher Conley

 

[warpboy]

hello,
i had some problems with 48v, the infos you give are really helpfull for diy'ers. the last problem i had was due to the 48v led indicator. Result : transistor oscillations :evil: .
the response of Rascalseven :
http://www.groupdiy.com/index.php?topic=24132
:thumb:

 

[lofi]

may i take the oportunity to drop my jaw!!!

beutiful!!!!!

Iain

 

[madriaanse]

Hi Conleycd,

I like the JLM PSU's a LOT!! They're very clean, easy to build and cheap. I've been using their ACDC to power my Neve's and it's working great. I have noticed that the +24V LM317's get pretty toasty when you power two channels of 1290/1073, so I've since "remote mounted" them to a large 50W TO-3 heatsink.

(this one: http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=HS117-ND)

I know that's probably complete overkill but it keeps them nice and cool. :green: By "remote mounting" I mean soldering wire leads to the PCB where the LM317's normaly sit and soldering the LM317's to the wires (1/8" heatshrink around the LM317 leads). The +48V LM317 doesn't get as hot, and it seems fine with a much smaller heatsink. I've remote mounted those to a 10W TO-220 heatsink: (this one: http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=HS276-ND)

I also calculate 500mA of current draw per channel for 1290/1073 modules, which again is VERRRRY conservative (read: overkill), but I like building things like a tank - especially when it comes to PSU's.

Warpboy: did you hook up 48V per my instructions at the beginning of this thread? Can you take some pics of your layout and explain how you wired things?

Lofi: Thanks for the kind words!! :thumb:

All the best,

M.

 

[madriaanse]

Good news, the Carnhill transformers will be **a lot** easier and faster to get at a much lower price from: http://www.audiomaintenance.com/acatalog/Transformers_and_Inductors.html

I've updated the BOM to reflect this:
http://www.musiciansgig.com/ez1290/1290BOM.xls

Thanks Colin (Slenderchap)!!!!

 

[ipagel]

Hi M
what is the difference between Carnhill vtb9049 or vtb1148?
or is it just size?

thanks mark

 

[buschfsu]

i got my carnhills from audio maintenance today. i got the smaller 1u output transformers so my 2 channels will fit in 1u!!!!
ill post when they are up and runnin

thanks again!!

 

[Slenderchap]

The only difference between the VTB9049 and VTB1148 is the size of the connector board (VTB1148 being narrower);

http://www.audiomaintenance.com/acatalog/Transformers_and_Inductors.html

If you click on the photos it will show them in detail... you can see the size difference.

Colin
www.audiomaintenance.com

 

[ipagel]

thanks colin thats what i thought. :thumb:

 

[madriaanse]

Our industrious Canadian friend Bluzzi has generously provided us with a consolidated BOM with prices etc. This is very handy if you're just building 2 channels! Pls see:
http://musiciansgig.com/ez1290/Consolidated_1290_BOM.xls

Thank you Bluzzi!!!!!! :thumb: :thumb:

Buschfsu: sounds like you're getting close to wrapping up your mic pre. I definitely like the 1U idea. I'm looking forward to the build pics!!

M.

 

[ffaudio]

I wanted to build a 2 channel version in 1u size, but can't pick up the pcb's right now. Are you going to be selling them for a while?

 

[outoftune]

just to let everyone know....the fivefish 2448 will work perfectly for this pre. I just ordered one with the torroid powersupply kit since digikey didnt have the amveco in stock...more info here: http://www.fivefish.net/diy/