neumann v475 pimping ...

[[silent:arts]]

dingo,

it is:

PCB layout: no
etch yourself: no
available components: no

it is just the use of original Neumann summing amps ...

 

[milton99]

I'm almost done with my summing box now (thanks for the PSU and you advices Volker).

There is one thing I was wondering about. What was the original design of a Neumann console ? Did it use one V475 module for every stereo channel ?  Or did it involve passive summing that was fed further into  V475 (like in Volkers design) ?
In other words: what would sound better (closer to original Neumann console) - 16 channels into one V475 OR 16 channels into 8 V475's ???

 

[[silent:arts]]

In my box there is no passive summing.
(like in any Neumann console - and it is not my design )

While active vs passive summing looks similar at the front end (two resistors for each channel),
people get confused ...

for your last question: 100 channels into one V475 is better / more original / like Neumann did / whathowever than 16 channels into 8. If you want those 8 outputs as a sum together you would need a 9th V475 btw

 

[xjazzwreck]

Hi Volker, I received the two POSPSUs I ordered, thanks for the great service! Next project is to replace caps on my v475b and build up a 16 channel summing box similar to yours hopefully...

 

[Autophase]

Hi Guys, I hope someone cal help me with this.
I had a V475-2c on the shelf for a while, I have just put together a small board that takes 8 channels (4 Stereo) and sums them through the 5k11 resistors much like volkers unit only with less channels. I also have volkers POSPSU for this project.
My problem is, I'm having trouble reading the schem as its quite faded, I need to know which pins of the IO to connect my +&- in and +&- out and which pins to use to hook up the power supply.
Any advice would be greatly appreciated.

 

[mitsos]

check the other versions at kubarth.com.  Pinouts look to be the same with the A version, and it's got better contrast.

 

[Autophase]

Hi guys, I need a little help with the power supply.
I'm using Volkers POSPSU, I bought a 2x12 torroid transformer, I have wired it in series and I seem to be getting 30 Volts AC from the transformer, not the expected 24 volts.
When I hook the transformer up to the POSPSU I'm getting a reading of 37 volts DC from the other end of the power supply, again, not the expected 24 volts.
Any advice would be greatly appreciated

Edit: I tweaked the adjustable pot down, now i get exactly 24V DC from the power supply,
Should I be bothered by the transformersoutput discrepancy?

 

[radiance]

Should I be bothered by the transformersoutput discrepancy?

No, as long as  things stay within margin heat wise > big enough heatsink

 

[Autophase]

Hi guys,
I need a few pointers with wiring up the V475-2c
1:From my understanding, the connector pins only have EVEN numbers (2,4,6,8 - 32) is this correct?

2: looking at the connector face on, with the PCB on the bench and the transformers pointing up, The LOWER RIGHT pin is 2A and the UPPER RIGHT pin is 2C. Is this correct?

3: Going by the V475-2c schematic on audio.kubarth.com and with help from another forum user, I think the pins I need are:
Input 1: 8A & 8C (does it matter which is + or - from the signal? I assume which ever I opt for must be the same on both inputs otherwise phase will be opposite? or am I way off here?
Input 2: 26A & 26C
Output 1: 12A & 12C
Ouput 2: 22A & 22C

4:14A and 18A for the + rails from my power supply (I'm using Volkers POSPSU, do I just connect the POS output of the supply to one of the pins then put a link wire between them so they both get power?)

5: If question 4 is true, then i would assume 14C & 18C is just connected to the GND output of the POSPSU?

Thanks in advance for any responses, hopefully if the above are answered this will serve a clear directions for other newbies like me.

 

[radiance]

3: Going by the V475-2c schematic on audio.kubarth.com and with help from another forum user, I think the pins I need are:
Input 1: 8A & 8C (does it matter which is + or - from the signal? I assume which ever I opt for must be the same on both inputs otherwise phase will be opposite? or am I way off here?
Input 2: 26A & 26C
Output 1: 12A & 12C
Ouput 2: 22A & 22C

8a & 8c = input
12a & 12c = output

4:14A and 18A for the + rails from my power supply (I'm using Volkers POSPSU, do I just connect the POS output of the supply to one of the pins then put a link wire between them so they both get power?)

14a = +V
10a = 0V

5: If question 4 is true, then i would assume 14C & 18C is just connected to the GND output of the POSPSU?

Thanks in advance for any responses, hopefully if the above are answered this will serve a clear directions for other newbies like me.

You can check this all with a DMM set to continuity check (the beeper thingy ) and probe both pins and places you think the pin is connected to.
I had a quick look at the schematic but it's only one channel they're showing.
I would ALWAYS measure to make sure I'm  using the correct pins.



http://audio.kubarth.com/rundfunk/getfile.cgi?f=F%2C3%2CS%2CCDS%2C%234V.5]V%2BVYE%3D6UA%3BFY%3F5C0W-2TR0U]S8VAE%3B2YG%3A68%60%0A

 

[Autophase]

This may sound like a silly question, but on the schematics for the various V475 revisions, there's more than one pin labelled next to some of them.
Does this mena exactly that, that any of the 3 labelled pins can be used for +24V for example?

 

[radiance]

This may sound like a silly question, but on the schematics for the various V475 revisions, there's more than one pin labelled next to some of them.
Does this mena exactly that, that any of the 3 labelled pins can be used for +24V for example?

Yes...and again, you can check this with a DMM set on continuity test (the beeb)...

 

[Autophase]

Right, I have this all wired up now, I have tested each of my stereo pairs individually (cant do a full test of the summing untill my ADA8000 arrives) and I have to say the v475-2c sounds amazing, i ran my supernova through it (a big digital synth) and the box definately adds something, it makes the sound smoother but without any loss of detail in the highs.
I'm actually surprised how silent the unit is, i didnt recap the neumann yet there is no detectable hiss at all.
I intend to use the device for mastering to sum 4 stereo pairs from Adat then back in through my RME as a single stereo pair, just to add a little analogue flavour to my otherwise totally digital studio. I will post some audio comparisons in the next couple of weeks so you can hear it in action.
Big thanks to Volker for inspiring this build, and forum contributors who guided me.

I have 1 question about sheilding, I used sheilded cable to connect all the the XLR's to my summing network and the summing network to the V475. I connected all of the ground pins of the XLR's together in series, with the last 1 going to my ground point, I did the same with the v475, it all goes through the mains earth pin (I'm in the UK) and as I said the unit is silent with regards to noise floor. However I have not connected any ends of the cable sheilding to the ground, do you think this is necessary as the unit is already so silent? I read somewhere you only need to connect 1 end of each piece of sheilded cable to ground any interference that is caught? What are your thoughts on this?

 

[[silent:arts]]

the shield of the cable is part of the case, not audio ground.
one side (only) to XLR pin1 is totally right.

 

[Autophase]

the shield of the cable is part of the case, not audio ground.
one side (only) to XLR pin1 is totally right.

So just to be clear, 1 end of the sheild is connected to Pin 1 of the XLR, and Pin 1 is also connected to the case at point of entry? is this correct?

I have mounted my V475 & the POSPSU with metal PCB spacers, so the grounds of the power supply and the amplifier are also in contact with the case. Is that how it should be done?
So what goes to the earth pin of my IEC socket?

I have searched the forum regarding XLR sheild and I have found differing answers.

 

[Autophase]

Hi guys,
I finally got round to finishing this (I will post pics later) Its just in a very simple metal box, and I only went for 8 inputs in XLR, as that was all i needed to sum from my ADAT. Good to know that I can expand at any time.

Anyway, it is working almost perfectly, it sounds amazing, and the noise is so low I'm really pushed to hear it in the scilence.
However I have noticed that its throwing out more output on the right hand side than the left, not much, maybe 3db louder. I intend to diagnose it this evening with some test tones and confirm if:
1: its one of the outputs from my ADAT (bought second hand)
2: its one of the inputs on the summing box
3: its the output of the V4752c its self.

Now, if it turns out to be the V475, where should I look to rectify this?
Could it be the POSPSU? could one side be getting more voltage than another?
Does the V475 have any input output trims, bearing in mind I havent used any of the RG pins.

Any wisdom would be greatly appreciated
cheers.

 

[magu]

Hello

I'm building summing mixer based on V475-2C. 16 in, 2 out. Without any gain pots, just clear summing.
Can anyone send me pictures of his V475-2C pin connections and wireing?
I'm hearing noises from ground and have problems with panning.

Sorry for lame favour, but this is my firs DIY project.

 

[Tomess]

Hi there!

I bought myself a v475-2 and finished recaping. Now it's time for the PSU. I'm just wondering if there's any PCB out there. I downloaded the plan from silent:art. Is it possible to buy the board somewhere?

Greets, Tomess

 

[home_listening]

Hi, No intention of dredging an old thread, but here I go...

I'm currently assembling a small 8ch/16output sidecar from a few old D&R channel strips I picked up a while ago, running it into a V-475-2A to make a small mixer. Unfortunately the channelstrips have unbalanced outputs, so I'm was thinking of using the trusty ThatCorp 1646 as a differential before the summing amp.

My question is this:

Do I need to use two for each of the 16 channels (L+R)? I would have to use one for each of the left and right outputs so things would get costly. Or can I simply perform the summing, then balance the left and right channels before the summing amplifier?

Any help greatly appreciated, Thanks.

::Edit::

Or option 3, run all the channels into the unit unbalanced. I remember an earlier post advising connection of the grounds to the negative rail but not recommending doing this too many times.

 

[prescott]

Help me pls!

which one to buy for summing amp:

http://www.vintagetools.de/Vintage-Modules/Other-Amps/V-475-2C-dual-summing-amp.html?listtype=search&searchparam=475

http://www.ebay.com/itm/Neumann-VINTAGE-Dual-Preamp-V475-V475-2-SUMMING-AMP-/310607796040?pt=US_Vintage_Pro_Audio_Equipment&hash=item4851aad748

Thanks!