neumann v475 pimping ...

[[silent:arts]]

Could you try with yours if you have something similar please ?

You can find my crosstalk measurements in post 2

 

[lars on]

Oh yes, I missed it.
So it means that is normal to hear crosstalk ?

I always have crosstalk...
I'm using shielded wires for each channel...

Any idea to help me ?

 

[lars on]

Silent:art

Could you explain to me your setup for mesuring please ?

I made a measure with Voltmeter : I send 1Khz at 0,775 Volt in Channel 1, then I measure alternative current in channel 2 and I claculate with this formula : Crosstalk db = 20log(Vout Ch2 / Vout Ch1).

I find 51,61 db, minus I guess. And it's far from the -105 db from your graphic...

 

[[silent:arts]]

See attachement

 

[lars on]

Thank you.

Just like a noob I don't exactly understand everything.

Should I feed an input with +20 db (10Volts) ? what kind of db ?

And what is the V = 0 db ? 

 

[[silent:arts]]

V = Gain
You have 0dB gain with the resistor values shown.
The +20dBm is not important (you crosstalk will be worse), but the resistor values are.

 

[lars on]

Ok thank's Volker.

I put the resistors in place and I'll do the test tomorrow.
And I'll use the formula. I hope I'll find the same result that the one
in your graph or in the doc. Something like crosstalk >100db between L/R.

 

[lars on]

Do you think that the crostalk data 100db is the measure of channel1 to channel 2 +  channel 2 to channel 1 ?
In that case my measure is good.
In other case my measure is half what I should find...

 

[lars on]

Hi every one again,

I don't know what happen but I lost sound in the left channel ! ! ! ! ! :'( :'( :'(
If I input a standard kick I hear only a very low clic !!!!!!

Any idea is very welcome !

Thank's

 

[lars on]

LUCKY and not lucky.

I just found what it was and I broke a NE5534 !
I switched the Right ones with the Left ones and the result is clear.
I don't know how it happened but I found the bug...

I hope it can help some...

Cheers

 

[lars on]

Another annoying question  ;D

How did you wire the ground ?
How the earth can be isolated from the ground of the board ?
I mean, the 0V from the PSU is connected to both sides of the board which are
connected to the ground of inputs and outputs !!?

Thank's for answers

Cheers

 

[[silent:arts]]

How did you wire the ground ?

I do have a star ground.

How the earth can be isolated from the ground of the board ?

No need to.

 

[lars on]

Thank's Volker.

Just need to star ground signal
ground and case  together ?

 

[[silent:arts]]

Just need to star ground signal
ground and case  together ?

Yes

https://www.rane.com/note151.html

 

[lars on]

Nice doc !

Thank's a lot

 

[noisear]

Hey Guys,

I got a couple of Protec V-1536 summing amps which looks quiet similar to the V475. I do not have schematics, but I managed to find out the pinouts for myself. They are working and sounding pretty fine. The transformers are Pikatron (labled for Protec).

I have three questions (or need your opinions):

- There are three small PCBs per channel (standing upright). The one in the middle is called MF01 (marked with the red arrow) and seems to be the highcut-filter. With the small trimmer on this PCB, I am able to move the filter frequency. It should be possible to throw the whole PCB off the V-1536, right? Just have to find the correct positions for the bridges I have to install instead. Any chance to destroy anything? I have a couple of them, so I can try it more than one time, but destroying it is not my aim : )

- On the left, there is a small blue jumper (marked with the green arrow) where I can choose between 0dB, +6dB and +16dB. If I want to install a master-level-pot, this would be the correct place, right? Perhaps I just use a 3-position switch for the given values, but as I have a couple of these cards, I also can try it with a rotary and finer steps...

- I did a small resistor-network on a project PCB. I really like it and it offers 32 channels, but the 0,1% resistors for L and R are pretty close to each other. Will this defenitly cause crosstalk-problems? For sure, I will give it a try, but maybe you are sure that it will make problems... If so, I will use it just for L and build up another board for R (than 64 channels...) I will post pics of the board in the following...

Thanks for your suppport,

Roman.

 

[noisear]

and here the network board...

 

[noisear]

... and the soldering side...

 

[aleev]

Hi! Can anybody supply me with information about Protec (Haufe?) RK286/3 transformers? Many thanks!!

 

[timtom]

Hi! Can anybody supply me with information about Protec (Haufe?) RK286/3 transformers? Many thanks!!

This is the data from the RK286/1