Looking to make a battery box

[XaiuM]

I'm looking to make a battery box to power my electret condenser mics that I will be plugging into my MD for recording purposes. This box also must have bass rolloff and level control. Pretty much exactly like this:

http://www.soundprofessionals.com/cgi-bin/gold/category.cgi?category=310&item=SP-SPSB-1&type=store

I haven't found any schematics yet, so I was hoping that one of you could point me in the right direction. This unit must be as steathly as possible too. Thanks!

 

[XaiuM]

No suggestions? I might be able to draw up a schematic myself, but if there's already one out there, then it would save some time?

 

[Scodiddly]

Do you need bass rolloff during recording, or could you do that later at home? That feature adds a fair amount of complexity and bulk to a battery box.

Really you could try plugging your electret capsules right into the MD mic input- the "plug in power" is enough to run typical capsules.

 

[Category 5]

[quote author="Scodiddly"]Do you need bass rolloff during recording, or could you do that later at home? That feature adds a fair amount of complexity and bulk to a battery box.

Really you could try plugging your electret capsules right into the MD mic input- the "plug in power" is enough to run typical capsules.[/quote]

The bass rolloff is not any more complex than building a battery box without it. You have to use a cap to keep DC off the preamp anyway. You simply choose the value based on the desired bass roll-off. I can't remember the formula but you need to know the input impedance of the minidsc or preamp, and then you can pick the capacitor value based on the desired roll-off.

Shane

 

[CJ]

If you are doing what I think your doing, check this article out , if you haven't already:
http://www.harmony-central.com/Other/mic-faq.txt
:guinness:

 

[XaiuM]

Thanks for all the replies. I haven't fully looked through the article - I will - but how many db per decade does a bass rolloff typically have to sound the best? My friend is helping me with the project, and asked me this question when talking about building one.

 

[Category 5]

A bass rolloff at around 80-150 is useful, depending on what your source material is. If you are recording bands indorrs you wouldn't belive how much the bass can build up with the small omni capsules.

Again, you'll need to know your input impedance or you can't meaningfully select the proper caps.

Also, if you have a way to roll off the bass after the fact then you can build the box without a bass roll-off and worry about that later.

Shane

 

[XaiuM]

Would an after-the-fact rolloff hurt the audio quality? I don't see how it would, and since your suggesting it, it makes me think theirs no difference at all. As I understand, bass rolloff would just chop the low frequencies out that are under a certain freq?

 

[Scodiddly]

[quote author="XaiuM"]Would an after-the-fact rolloff hurt the audio quality? I don't see how it would, and since your suggesting it, it makes me think theirs no difference at all. As I understand, bass rolloff would just chop the low frequencies out that are under a certain freq?[/quote]

Only a worry if the bass content tends to overload your recorder's input. You could even do it in software before burning a CD, which is what I use to do when converting vinyl records to CD.

 

[Category 5]

Check out this link


http://www.minidisc.org/homemade_mics.html


Shane