6U 8 channel Neve mixer

[baadc0de]

Thank you, forum, for your patience and answers in my times of need.

When I started DIY, what I was really after was some Neve EQs and preamps - something nice to record my drums and have fun with at mix time. Prices for used or new ones being what they are, I wanted to make some myself, but quickly realized that this wasn't a project for beginners... so the idea was stashed away, still stuck at the back of my head.

After a few years, when bruno2000 presented his 1084 dual mid PCBs, I knew I found what I was looking for. So after some back and forth, complications, sweat, blood and above all, work, here is a sneek peek:



She will be completed tomorrow, the four missing channels are in varying state of completeness, but they all still lack the gain swtich assembly and fitted knobs, thus they are not installed.

Sitting behind the channels is a digitally controlled (but still analog) MDAC mixer (ala Duality) that feeds a pair of full BA283. All 31267 transformers are BBC-era originals. The rest of the iron is courtesy of Oliver at AMI (thanks!). Remote control via OSC / MCU. Most possibly the only class A neve console to have an ethernet jack and its very own IP address 8)

 

[bruno2000]

That is such a great build.  You took my idea to a new level.
Those look fabulous!
Best,
Bruno2000

 

[culteousness1]

Quality speaks for itself!

I would like to get some details about it's digital control...

Cheers,
Carsten

 

[baadc0de]

Thanks for the kind words & likes.. Also, bruno2000, these wouldn't be possible without your huge amount of work and generous decision to share your design with the rest of us. So, thank you again, for the opportunity to take it to the next level, as you say

Regarding the mixing part..

The unblanced out from each channel is taken to a stereo MDAC (an AD5545 /AD4004 combination) where they are multiplied in such a way that the analog signal is the reference voltage and the DAC signal is the set gain constant with 16-bit precision. In this case, the DAC generates just a precise voltage to do (analog) multiplication with.

After this stage, the results are summed in a Neve passive bus kind of way, taken to another stereo MDAC, where master level is controlled and then leaves to the BA283 stages via 31267 transformers. So all signal manipulation and summing is actually analog, just the control bit is digital

Speaking of which, the MDACs are controlled with a Beaglebone (revision 6 I believe) which is a ~700Mhz ARM machine running Linux Angstrom. I have written some software (in Java 7.0! hehe) that is an mDNS responder, an OSC server and RTP node. By using DHCP and mDNS, the machine is put on your LAN and voila, in at most a minute, service discovery is done and it's ready to receive fader and pan set events via OSC or RTP.

In light of all the things this project is, it was quite a bit difficult to pick the right room. It's got preamps, it has equalizers, makes a lot of use of the truth table, I definitely have views about it that belong in the Studio A room and so forth..

Today we found out some PCB switches on last two channels were soldered on backwords and we ran out of some steel profiles that mount the switch PCBs. So... off to next day

 

[delaymix]

Great project! 

 

[Scrappersa]

It is absolutely beautiful! I'm curious, what kind of rack did you use to hold all of the modules in? I love the design.

 

[baadc0de]

It's a rittal 6U eurorack, ripack-easy or something like that.

You can read more about it here
http://www.rittal.com/products/katalog.asp?ViewAt=2-2-3556-3561&Dom=en&lang=GB&NavName=Ripac%20EASY%20for%20backplane

In essence it's the same, or at least compatible, eurorack / eurocard system as used by the modular synth industry and Ian Bell's tube mixer. The original bruno2000 design was similar, but in 3U euro chassis so that and Ian's (ruffrecords) efforts led me to what I believe is the best format for modular mixers. The backplane (well, motherboard is what we call it here) adheres to the VME specification and uses VME 96-pin connectors. These are not neccesary for the pin count, but german broadcast consoles and ruffrecords console all use this same format: eurocards with 96-pin VME connectors so I opted to use the same ones and adhere strictly to VME spec regarding board size, connector positioning etc.

We hope to do final assembly (after some fault finding yesterday) today and have a nice photoshoot tomorrow

 

[ruffrecords]

What has been your experience with the removal force required with the 96 way connectors?

Cheers

Ian

 

[bruno2000]

It's a rittal 6U eurorack, ripack-easy or something like that.

You can read more about it here
http://www.rittal.com/products/katalog.asp?ViewAt=2-2-3556-3561&Dom=en&lang=GB&NavName=Ripac%20EASY%20for%20backplane

In essence it's the same, or at least compatible, eurorack / eurocard system as used by the modular synth industry and Ian Bell's tube mixer. The original bruno2000 design was similar, but in 3U euro chassis so that and Ian's (ruffrecords) efforts led me to what I believe is the best format for modular mixers. The backplane (well, motherboard is what we call it here) adheres to the VME specification and uses VME 96-pin connectors. These are not neccesary for the pin count, but german broadcast consoles and ruffrecords console all use this same format: eurocards with 96-pin VME connectors so I opted to use the same ones and adhere strictly to VME spec regarding board size, connector positioning etc.

We hope to do final assembly (after some fault finding yesterday) today and have a nice photoshoot tomorrow

Thank you for the kind words!  Can't wait to see the "porn" photos!
Just a note, my rack is a somewhat un-standard 4U rack, and the panels are 2" wide.
Best,
Bruno2000

 

[baadc0de]

There's just one shot and I'm not terribly stoked about it ... but here you go mates. I have a list of things to still correct (fancy ramped phantom isn't working, some hi-eq points on two channels are not triggering, some switches aren't tightened to the same standard as the other ones, but I digress..)



The remove force on DIN 96-pins was entirely to my expectations. Not too loose, not too tight. What about your experience on this matter, Ian?

 

[grubbyliver]

WOW!

 

[pucho812]

hats off to doing such a great job...  that is cool

 

[sharpeleven]

Wow, great job!!

how's the sound? Did you get a chance to see how it does next to an original?

 

[baadc0de]

The sound coincides with what people are saying about Neves in general.. the channels have a thick and big sound, the mixer makes everything you put through it sound more alive and real.

That said, I don't have an original to check against, though I think it would be very very close. I do have original outputs to check against, and that worked out very well. There are NOS transistors and an original line input transformer in each channel, so most of the elements are original or as close as can be, except for the EQ capacitors, which are WIMAs instead of tropical fish capacitors. I wanted to go with SoZo's line that is a supposed drop in replacement for those, but they didn't want to be bothered with all the extra values I wanted to have. Still, it doesn't seem to have that much of an impact anyway, since it sounds (imo) very good and it's the best EQ I have used, ever.

 

[ruffrecords]

The remove force on DIN 96-pins was entirely to my expectations. Not too loose, not too tight. What about your experience on this matter, Ian?

My first mixer used a pair of 64 way DINs and I could not pull the channel cards from the sockets. It had captured knurled fasteners just like they have on the Neve modules and if you tried to put the module out by one of those it came out but the module stayed in.

Cheers

Ian

 

[baadc0de]

Hmm, mine are from Harting, maybe that's a difference? Definitely don't have an experience like that.. with that many more pins and it still goes out with just thumb pressure.

http://uk.farnell.com/jsp/search/productdetail.jsp?sku=1097072

 

[baadc0de]

Eventually got a better pic

 

[MagnetoSound]

baadass 

 

[jplebre]

Insane. Trully insane. I'm going to have nightmares.
Having worked with the real thing, i envy you.

I so want something like that.

Soon. Soon. Still giving my first steps on DIY/electronics

 

[bruno2000]

That is so very cool.  Congrats!
Best,
Bruno2000