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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: YYzepp on December 17, 2011, 09:35:20 PM

Title: DIY Battery Box: help on caps and resistors
Post by: YYzepp on December 17, 2011, 09:35:20 PM
Hello guys. I'm a newbie here. Thank you all for making this site a wealth of knowledge and experiences. I've a question about creating a battery box with no rolloff to use with a Roland R-05. These are the impedance specs from the manual (all I've got to go on for now):
mic (low) input: 5k
mic (hi) input: 7k
line input: 8k

I plan on buying a pair of Chris Church's CA-14 cards. While waiting to get the $ up for them I figure I'll build a battery box. I'm a drummer and I'd like to record my bands' shows, as well as occasional club or arena rock concerts. I happen to have some 10uF non-polar electrolytic caps and was wondering if using them, along with 8.06k metal film resistors, would be flat enough and have enough power to the CA14's (or most other minimics)? If my calcs are right this should roll off pretty low around 2-3Hz depending which input on the R-05 I use. Would this work well or should I choose some other values for either the caps or resistors? Thank you.
--
Tony

Merry Christmas and Happy Holidays!
Title: Re: DIY Battery Box: help on caps and resistors
Post by: Church-Audio on December 18, 2011, 12:14:22 PM
Hello guys. I'm a newbie here. Thank you all for making this site a wealth of knowledge and experiences. I've a question about creating a battery box with no rolloff to use with a Roland R-05. These are the impedance specs from the manual (all I've got to go on for now):
mic (low) input: 5k
mic (hi) input: 7k
line input: 8k

I plan on buying a pair of Chris Church's CA-14 cards. While waiting to get the $ up for them I figure I'll build a battery box. I'm a drummer and I'd like to record my bands' shows, as well as occasional club or arena rock concerts. I happen to have some 10uF non-polar electrolytic caps and was wondering if using them, along with 8.06k metal film resistors, would be flat enough and have enough power to the CA14's (or most other minimics)? If my calcs are right this should roll off pretty low around 2-3Hz depending which input on the R-05 I use. Would this work well or should I choose some other values for either the caps or resistors? Thank you.
--
Tony

Merry Christmas and Happy Holidays!
I will send you the parts to make one of my battery boxes when you buy your mics. Its pretty easy. Just include an extra $10 for parts.

Chris
Title: Re: DIY Battery Box: help on caps and resistors
Post by: hi and lo on December 18, 2011, 12:43:28 PM
Hello guys. I'm a newbie here. Thank you all for making this site a wealth of knowledge and experiences. I've a question about creating a battery box with no rolloff to use with a Roland R-05. These are the impedance specs from the manual (all I've got to go on for now):
mic (low) input: 5k
mic (hi) input: 7k
line input: 8k

I plan on buying a pair of Chris Church's CA-14 cards. While waiting to get the $ up for them I figure I'll build a battery box. I'm a drummer and I'd like to record my bands' shows, as well as occasional club or arena rock concerts. I happen to have some 10uF non-polar electrolytic caps and was wondering if using them, along with 8.06k metal film resistors, would be flat enough and have enough power to the CA14's (or most other minimics)? If my calcs are right this should roll off pretty low around 2-3Hz depending which input on the R-05 I use. Would this work well or should I choose some other values for either the caps or resistors? Thank you.
--
Tony

Merry Christmas and Happy Holidays!

It would be better to use polypropylene capacitors rather than electrolytic capacitors. They'll work just fine, but are generally considered to be inferior for audio.  Anything above 2.2uF will be fine for your listed impedance values, but there's no harm selecting the biggest value possible.

I don't know what value bias resistor Chris would recommend. I generally use 10k for a 9v battery box, but really only work with Panasonic capsules.
Title: Re: DIY Battery Box: help on caps and resistors
Post by: YYzepp on December 18, 2011, 01:49:24 PM
Whoah! I must edit my reply because I somehow missed your reply, Chris. I must have scrolled real fast or ...?...  anyway, thank you for the offer. I will gladly take you up on it! Thank you for responding.

Hi and low and mshilarious, thank you for replying. I know the non-polar's will be fine for this app as I've used them before for other audio projects I've done. The regular polarized electrolytics, as well as tantalums, are the ones not to use. I'm good with basic electronics and circuitry, even better with a soldering iron, but still ask when I'm not sure of something. IIRC the formula to figure what the rolloff would be is rolloff freq=1/((6.28318)x(recorder input impedance)x(capacitor value in decimal form))   correct?  Am I cutting off anything on the upper end by starting to cutoff around 3Hz or does the upper end not get affected by the cap value?
--
Tony
Merry Christmas and Happy Holidays!
Title: Re: DIY Battery Box: help on caps and resistors
Post by: Church-Audio on December 18, 2011, 03:54:20 PM
Whoah! I must edit my reply because I somehow missed your reply, Chris. I must have scrolled real fast or ...?...  anyway, thank you for the offer. I will gladly take you up on it! Thank you for responding.

Hi and low and mshilarious, thank you for replying. I know the non-polar's will be fine for this app as I've used them before for other audio projects I've done. The regular polarized electrolytics, as well as tantalums, are the ones not to use. I'm good with basic electronics and circuitry, even better with a soldering iron, but still ask when I'm not sure of something. IIRC the formula to figure what the rolloff would be is rolloff freq=1/((6.28318)x(recorder input impedance)x(capacitor value in decimal form))   correct?  Am I cutting off anything on the upper end by starting to cutoff around 3Hz or does the upper end not get affected by the cap value?
--
Tony
Merry Christmas and Happy Holidays!

I use 4.7k resistors and 10uf 20v caps Tantalum. They are small and work great for this application.

Chris
Title: Re: DIY Battery Box: help on caps and resistors
Post by: YYzepp on December 18, 2011, 07:32:53 PM
I use 4.7k resistors and 10uf 20v caps Tantalum. They are small and work great for this application.

Tants? I thought they were a no-no in the audio path but I guess it depends upon the circuit and application.  I learn something new every day! Thanks Chris.
--
Tony

Merry Christmas and Happy Holidays!
Title: Re: DIY Battery Box: help on caps and resistors
Post by: Church-Audio on December 19, 2011, 10:20:39 AM
I use 4.7k resistors and 10uf 20v caps Tantalum. They are small and work great for this application.

Tants? I thought they were a no-no in the audio path but I guess it depends upon the circuit and application.  I learn something new every day! Thanks Chris.
--
Tony

Merry Christmas and Happy Holidays!
Some of the most expensive preamps in the world some of the most highly sought after use tantalum caps....and when size is an issue there is no subtitute. They do make small electrolytics but I have never had an issue in this application.
Title: Re: DIY Battery Box: help on caps and resistors
Post by: marksk on April 04, 2013, 03:57:02 PM
i recently built the 3-wire battery box in this  (http://taperssection.com/index.php?topic=72994.msg976869#msg976869) thread and was very pleased with the results. i would like to build another one (try to put it in a smaller case) but am out of caps. the caps i used, 10uF WIMA MKS 2-XL (http://www.wima.cn/EN/mks2xl.htm), are no longer in production, which is too bad, since this was a nice sized capacitor. can someone please recommend some replacements? i will be placing an order with mouser in the next few weeks and would like to order them at that time. also, i'm considering trying my hand at using smd components. any recommendations there?

thanks!
mark
Title: Re: DIY Battery Box: help on caps and resistors
Post by: marksk on April 04, 2013, 04:37:04 PM
thanks. i had looked at those before but was under the impression i should stick with film since these are in the signal path.
Title: Re: DIY Battery Box: help on caps and resistors
Post by: MIQ on April 07, 2013, 02:08:37 AM
Marksk,

Jon is right.  If you are still interested in a film cap similar to what you bought before, check out Mouser # 505-MKS210/50/20

-MIQ
Title: Re: DIY Battery Box: help on caps and resistors
Post by: Church-Audio on July 31, 2013, 01:14:43 PM
Did you get that stuff I sent you yet?

Chris