First of all I am a studio engineer and and now reverting back to my
live days. I have just built a Jazz, Blues and Alt. Rock club and I
have 3 senn. wireless handhelds, and 6 senn wireless guitar packs. My
wireless guitar body packs say mic/line on the input plug 1/8". I have
some Audio Tech. ATM-35 mics for horns and drums and would like to plug
them in wireless. I need to build a phantom bodypack batt. powered.
My mics take 11v to 48v. I was thinking of building one with 1 or 2
12v batts and blocking caps but I thought I would get your guys ideas
first. which are the best caps to use and I would like to use AA Batts
instead of 12v batts cause that is what all my senn. stuff uses (AA
Batts.) What do you all say


Jesse "Tolomas" Newsome
Affordable Audio Solutions
Phoenix, AZ

Tolomas wrote:
I need to build a phantom bodypack batt. powered.
My mics take 11v to 48v. I was thinking of building one with 1 or 2
12v batts and blocking caps but I thought I would get your guys ideas
first. which are the best caps to use and I would like to use AA Batts

Use whatever batteries you like. Enough AA cells to make 12V or 24V
might be a bit big for a bodypack; 2 x small 9V batteries would take
less space.

For live sound, almost any capacitor will do. 3.3uF will give you a low
end rolloff of 48Hz into a 1k input (not likely to be less than that)

Your choices in increasing order of preferability (and cost) a

* Standard electrolytic (probably good enough)
* Low ESR electrolytic (cheap enough to consider)
* Polyester (will be big)
* Better plastics like polycarbonate (you're getting into audiophile
territory here and they'll be big too)

Check what resistor values you should use with your mics for phantom
less than 48V. My AKG bluelines specify something like the usual 6k8 for
48V, 2k4 for 24V and 680R for 12V (from memory). There is a DIN standard
for this which you can probbly look up.

After an unfortunate experience with a 4 track MD recorder and a
separate P48 supply, I'd recommend putting a pair of back to back 5.1V
zeners across the output of your box. That will limit the size of any
connecting/switching surges as the capacitors charge up.

My 0.02 Euro's worth...
Anahata

Tolomas wrote:
First of all I am a studio engineer and and now reverting back to my
live days. I have just built a Jazz, Blues and Alt. Rock club and I
have 3 senn. wireless handhelds, and 6 senn wireless guitar packs. My
wireless guitar body packs say mic/line on the input plug 1/8". I have
some Audio Tech. ATM-35 mics for horns and drums and would like to plug
them in wireless. I need to build a phantom bodypack batt. powered.
My mics take 11v to 48v. I was thinking of building one with 1 or 2
12v batts and blocking caps but I thought I would get your guys ideas
first. which are the best caps to use and I would like to use AA Batts
instead of 12v batts cause that is what all my senn. stuff uses (AA
Batts.) What do you all say

I say that five 9V batteries in series for 45V will weigh a whole lot
less than a whole stack of AA cells, and if you want to do anything else
you'll be into designing a DC-DC converter which is no fun.

Have you considered the Sennheiser butt plug transmitters which actually
provide phantom power?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Have you considered the Sennheiser butt plug transmitters which
actually provide phantom power?

Sure beats having a belt clip on it.

Rv!