Neumann W492 equalizer DIY project (PCB docs added)

[tuanuibi]

Hi guys,
I'm going to be mounting off board - do you think these pots would be fine?

http://au.mouser.com/ProductDetail/Bourns/3310C-001-103L/?qs=sGAEpiMZZMtC25l1F4XBU4NnHEok4CZwvdjENCK81TE%3d

Thanks in advance!

Very excited for this one!
Josh

 

[Markus_Krippner]

They look ok to me, but they're mono only.
Remember, you need 6 mono and 2 stereo pots per PCB.

...markus

 

[kante1603]

Hello and welcome,


yes,Markus is right.Just remember two of them must be duals.
Technically they're a good choice because they're conductive plastic types (keyword is "pots become scratchy").
Also they give very nice feel,I used a lot of them in a different project recently.

Udo.

 

[tuanuibi]

Thanks guys - good to be here!

I'll start hunting for the dual gang ones now.

I'm gutting half of a Tascam console and  replacing the EQ with this one on 8 channels - hopefully have something to show you 'soon'.. .

 

[Harpo]

Not so common avail.knobs that your pots 3.18mm shaft diameter call for...

 

[burglar]

Hi folks,

Planning on building two of these soon.  What power supply are most using for a dual mono unit?  If there is not a preferred kit would someone mind posting a schematic??

Many thanks

B

 

[kante1603]

Hi folks,

Planning on building two of these soon.  What power supply are most using for a dual mono unit?  If there is not a preferred kit would someone mind posting a schematic??

Many thanks

B

Hello,


specs are to find on the first page here,see schematics last page at bottom,it's +/-15vdc.
There are a lot of suppliers here who have nice little pcbs on offer.Gustav himself has them too,any dual rail psu will work.Depends where you are located I'd say.


Best regards and have fun,


Udo.

 

[burglar]

Thanks Udo,

Forgive my newbism, but I need + - 15vdc for both boards.  If my PSU has + - 15vdc how do I supply it to both channels of the EQ?

Cheers

 

[Gustav]

Thanks Udo,

Forgive my newbism, but I need + - 15vdc for both boards.  If my PSU has + - 15vdc how do I supply it to both channels of the EQ?

Cheers

Split the supply to each.

And if you are buying boards from me, get the VARI PSU, which has a split output on the board...

Gustav

Gustav

 

[burglar]

Thanks Gustav,

Finally, I should use a toroidal with dual 18v secondaries?  How do I calculate the current required on the power transformer?

Cheers

B

 

[audiophreak]

I'm pretty sure I used a spare mnats PSU pcb from the 1176 projects  (+)  and (-)  adjustable with trimmers

 

[jicama]

Hello guys I'm very confused at the at the shopping list of this project says 8 pots 10k linear dual, but now I'm reading only 2 needs to be dual!
And I know has to be conductive plastic does anyone knows if carbon type can work I have this pots

http://www.mouser.com/ds/2/54/ptd90-35260.pdf

Thank you for your help

 

[kante1603]

Hello guys I'm very confused at the at the shopping list of this project says 8 pots 10k linear dual, but now I'm reading only 2 needs to be dual!
And I know has to be conductive plastic does anyone knows if carbon type can work I have this pots

http://www.mouser.com/ds/2/54/ptd90-35260.pdf

Thank you for your help

No,they will become scratchy soon.


Udo.

 

[jicama]

Hello guys I'm very confused at the at the shopping list of this project says 8 pots 10k linear dual, but now I'm reading only 2 needs to be dual!
And I know has to be conductive plastic does anyone knows if carbon type can work I have this pots

http://www.mouser.com/ds/2/54/ptd90-35260.pdf

Thank you for your help

No,they will become scratchy soon.


Udo.

Thanks for the replay Udo,
And what about the dual pots? How come now I only need 2 dual instead 8?  Will work the same?

 

[kante1603]

Thanks for the replay Udo,

And what about the dual pots? How come now I only need 2 dual instead 8?  Will work the same?

Replay? ;D
O.K.,let's get serious.....
Only two duals are needed,you find them in the mid bands.Look at the schematics here:


https://docs.google.com/file/d/0B_XBYPfmG8pVMDkyMmRlNjEtZmQwMS00OTgwLWJkYzMtNWRmNGYyZTE1NTRm/edit?hl=en&pli=1


You can even see which ones must be dual by looking closely to their traces on the board.
The others were just dual for mechanical reasons,but not necessary.


Best,


Udo.

 

[jicama]

Thanks for the replay Udo,

And what about the dual pots? How come now I only need 2 dual instead 8?  Will work the same?

Replay? ;D
O.K.,let's get serious.....
Only two duals are needed,you find them in the mid bands.Look at the schematics here:


https://docs.google.com/file/d/0B_XBYPfmG8pVMDkyMmRlNjEtZmQwMS00OTgwLWJkYzMtNWRmNGYyZTE1NTRm/edit?hl=en&pli=1


You can even see which ones must be dual by looking closely to their traces on the board.
The others were just dual for mechanical reasons,but not necessary.


Best,


Udo.

Great news!  I can save a few bucks,  going to search them now

thank´s  Udo 4 da re-play!! ;D

 

[jicama]

Hello guys I'm very confused at the at the shopping list of this project says 8 pots 10k linear dual, but now I'm reading only 2 needs to be dual!
And I know has to be conductive plastic does anyone knows if carbon type can work I have this pots

http://www.mouser.com/ds/2/54/ptd90-35260.pdf

Thank you for your help

No,they will become scratchy soon.


Udo.

I found them! this should work right?
http://www.mouser.es/ProductDetail/Bourns/91A2A-B28-B15-B15L/?qs=sGAEpiMZZMtC25l1F4XBU0lMC8qKAKdNb%2fFsrRH3ibQ%3d

Cheers

 

[pvision]

To work out the current draw, look at the ICs, look up the data sheets for them and multiple the current consumption per IC by the total number in the unit.  That's the current draw, split across two rails.  I'd multiply that by at least two to give some spare capacity.  In practice, the current draw is tiny

To work out the transformer secondary voltage, look at the voltage range of the regulator inputs.  Pick a voltage that's in range, divide by 1.4 and that's your approximate secondary voltage.  If the rails are 15 - 0 - 15, the regulators will need 18-24 Volts approx.  That's DC, post-rectifier.  AC rectified averages 1.4 times the AC voltage so an 15 - 0 - 15 transformer will give about 21 volts DC to each regulator

To make life more interesting, your 15 - 0 - 15 transformer will read about 25 - 0 - 25 VAC with no load but drop sharply as soon as you put a load on it

It's a learning process, as I have found out!

Nick Froome

 

[Greg S.]

Yaeh, the difference between Peak and RMS  Voltages..
You should be 2 Volts above the needed one, lets assume +-15 DC are needed, so you should have min +-17V.

But don´t forget the Cooling at the regulator!

 

[jicama]

Hello I'm almost finish the eq but I was testing my power supply and the out put voltage is reading -19V my L7915 is not working properly my positive voltage is ok 15V, I've changed the regulator but still reading -19V what I'm I doing wrong?