I started a mic preamp

[Nikolay]

Hi friends I started a new project : mic preamp with ina217
I have 2 questions about how to make this preamp
First is I like to use a smaller volgage for phantom power. There is 2 resistors with 6k8 connected to pin 2 and 3 in XLR for the mic. Can I use resistors with smaller value, and use smaller voltage ?

Second: How can I "print" frontpanel graphics to my frontpanel?
Here is first version of the frontpanel:

and what kind of paints is usefull for metal painting.
Actually I will make this 19" rack in lazer cut technology, than paint..

Thanks

 

[chrissugar]

[quote author="Nikolay"]
First is I like to use a smaller volgage for phantom power. There is 2 resistors with 6k8 connected to pin 2 and 3 in XLR for the mic. Can I use resistors with smaller value, and use smaller voltage ?
[/quote]

No, you should use 6.8k resistors and 48V for phantom power. This is a standard.

After looking to the front panel I have a sugestion, do not label the potentiometer as ATTENUATE because it is a gain function. More apropriate would be GAIN.

Also a power LED would be good to have a sign that the PSU is working (easyer to troubleshoot if there is some problem)

chrissugar

 

[gyraf]

two things:

- The whole layout should probably be shifted a bit to the right, as you're a bit too close to the left edge. The power switch dosen't need that much space.

- The XLR's are too close to the bottom - they'll probably interfere with the box underside - specially the lower mounting screws.

Jakob E.

 

[mhelin]

[quote author="chrissugar"]standard.
After looking to the front panel I have a sugestion, do not label the potentiometer as ATTENUATE because it is a gain function. More apropriate would be GAIN.
[/quote]

Unless you use a regular logarithmic pot instead of the reverse one. Even then ATTENUATION would be a better label. How about "REVERSE GAIN"? What the h**l that means might someone someday think.

Btw. Which way you turn the water tap when you want to increase the water flow?

Some mics do work with P12 or P24 but the voltage must be regulated to these voltages. Don't know how big resistors you should use with these standards.

 

[Nikolay]

chrissugar I use attenuate, because I will use normal log potentiometers, and gain will be in left. I can't find reversed pots for gain

Power switch is like this who have lightning inside. other way is to use blue led

Jakob, now I see that all layout is in left.. (I fix this)

Inside the PCB board will be vertical and I think that XLR is in good position

BUT!! this is only first layout of this panel, and I will make changes.
Thanks of your opinion :grin:

Tell me please how can I make front panel. With laser engrave or some other way ?

Jakob I see all your products in your site and I like your front panels

 

[gyraf]

Nikolay,

If you post your location in your profile, it will be much easier to help you with locating components, processes and such..

Jakob E.

 

[Nikolay]

Sorry Jakob
I'm from Bulgaria

 

[gyraf]

Aah.. Europe..

Omeg in UK will sell you neg.log pots - so will musikding.de in germany.

marking of the front panel can be made several ways - try doing a search here - we've discussed it several times already.

Jakob E.

 

[mhelin]

http://www.alphastat.de/indexstart.html

Found this one: 63250-016
select 5k-log 41-click one
1.97 EUR piece

Frontpanels: http://www.wk-mechanik.de/
(http://www.shop.wk-mechanik.de/)
You can mekae the design with TARGET3001 (I think that's the name).

Another place is Schaeffer:
http://www.schaeffer-apparatebau.de/index.php?option=com_frontpage&Itemid=205