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Author Topic: 3 wire bass rolloff HELP PLEASE!  (Read 2730 times)

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Offline brn2rn

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3 wire bass rolloff HELP PLEASE!
« on: April 11, 2007, 12:58:53 PM »
Hi folks,

Since I am not too "electric" I am now on my knees and ask for your help: (..and I suck on math...)

I have a homebrew 3 wire battbox that drives a pair of AKG CK91 capsules with truly great results bulilt from the specifications in numerous threads around here.

Sometimes I run into very bassheavy situations where I´d like to have a filter to lower the massiveness of bass input.

Could someone please help me calculate resistors and caps for a 80-ish Hz rolloff???

I´d be happy as the LogLady in Twin Peaks for your help!

Offline brn2rn

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Re: 3 wire bass rolloff HELP PLEASE!
« Reply #1 on: April 24, 2007, 12:38:05 PM »
No one???

Alchemy

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Re: 3 wire bass rolloff HELP PLEASE!
« Reply #2 on: April 24, 2007, 03:09:06 PM »
Another thing you could do is run a high pass filter in post-production if you think you are catching too much bass. It seems you don't want to do that though.  ???

Offline boojum

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Re: 3 wire bass rolloff HELP PLEASE!
« Reply #3 on: April 26, 2007, 12:21:31 AM »
How about this circuit, if you want a battery box?   

2.2uF caps; 10kOhm 1% resistors or closely matched 5% resistors. 9 volt battery connector, female connector and male connector.
Nov schmoz kapop.

Offline Church-Audio

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Re: 3 wire bass rolloff HELP PLEASE!
« Reply #4 on: April 26, 2007, 01:13:59 AM »
No one???

Never use 5% because they will most likely be carbon resistors.. ALWAYS USE METAL FILM RESISTORS. .. Also dont use a 2.2 uf cap use a 10uf cap.. If you want to have a high pass filter and your input impedance is around 10k you can use a 330nf cap for about 80hz roll off...
You can use a DPDT switch for "swaping" out the caps in the circuit so you can have a full range or bass reduced filter... with the touch of a button. This is what I do for my preamp's

 
Chris


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Offline poorlyconditioned

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Re: 3 wire bass rolloff HELP PLEASE!
« Reply #5 on: April 26, 2007, 01:22:23 AM »
Hey, did someone else make AKG CK9x "actives" too?  Cool...

As far as rolloff goes, I never used/needed it.  If the capsules are powered correctly, they will not overload.  What are you recording into?  Maybe your preamp needs more headroom.  If so, try putting it directly into line input.  I found the AKG capsules very balanced, not too much bass, but not too little either...

  Richard


Hi folks,

Since I am not too "electric" I am now on my knees and ask for your help: (..and I suck on math...)

I have a homebrew 3 wire battbox that drives a pair of AKG CK91 capsules with truly great results bulilt from the specifications in numerous threads around here.

Sometimes I run into very bassheavy situations where I´d like to have a filter to lower the massiveness of bass input.

Could someone please help me calculate resistors and caps for a 80-ish Hz rolloff???

I´d be happy as the LogLady in Twin Peaks for your help!
Mics: Sennheiser MKE2002 (dummy head), Studio Projects C4, AT825 (unmodded), AT822 franken mic (x2), AT853(hc,c,sc,o), Senn. MKE2, Senn MKE40, Shure MX183/5, CA Cards, homebrew Panasonic and Transsound capsules.
Pre/ADC: Presonus Firepod & Firebox, DMIC20(x2), UA5(poorly-modded, AD8620+AD8512opamps), VX440
Recorders: Edirol R4, R09, IBM X24 laptop, NJB3(x2), HiMD(x2), MD(1).
** This individual has moved to user "illconditioned" **

Offline Church-Audio

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Re: 3 wire bass rolloff HELP PLEASE!
« Reply #6 on: April 26, 2007, 01:44:14 AM »
Hey, did someone else make AKG CK9x "actives" too?  Cool...

As far as rolloff goes, I never used/needed it.  If the capsules are powered correctly, they will not overload.  What are you recording into?  Maybe your preamp needs more headroom.  If so, try putting it directly into line input.  I found the AKG capsules very balanced, not too much bass, but not too little either...

  Richard


Hi folks,

Since I am not too "electric" I am now on my knees and ask for your help: (..and I suck on math...)

I have a homebrew 3 wire battbox that drives a pair of AKG CK91 capsules with truly great results bulilt from the specifications in numerous threads around here.

Sometimes I run into very bassheavy situations where I´d like to have a filter to lower the massiveness of bass input.

Could someone please help me calculate resistors and caps for a 80-ish Hz rolloff???

I´d be happy as the LogLady in Twin Peaks for your help!

I agree with Richard if you have a nice mic you dont really need a bass roll off. And can get away with it in post... And with the AKG mics I would for sure use 10uf caps...
Chris
for warranty returns email me at
EMAIL Sales@church-audio.com

Offline brn2rn

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Re: 3 wire bass rolloff HELP PLEASE!
« Reply #7 on: April 26, 2007, 01:56:59 PM »
Hi all,

Thanks a lot for the replies!

Yes Richard, I built a pair for a friend and I intend to build another pair for myself.
All possible only due to your research!!!
Thanks a million for that.

I actually agree with you that the filter isn´t needed, but my friend is nagging me about it due to him recording very bass heavy shows up close a lot.
His device is an R-09 so I think it would almost never overload or so.

When I tried his setup I just ran highpass in post processing just as you say.

But anyway I´ll try Chris filter suggestions.

Thanks again,
Thomas

Offline brn2rn

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Re: 3 wire bass rolloff HELP PLEASE!
« Reply #8 on: April 26, 2007, 02:01:23 PM »
Oh, by the way, Chris, why would I use a 10uF cap instead of the 2.2uF?
I think Richards schematics said 2.2uF.

Offline Church-Audio

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Re: 3 wire bass rolloff HELP PLEASE!
« Reply #9 on: April 26, 2007, 02:03:49 PM »
Oh, by the way, Chris, why would I use a 10uF cap instead of the 2.2uF?
I think Richards schematics said 2.2uF.
You can use a 2.2 but at 10uf there is no attenuation of low end what so ever. It will allow all the bass your mic is capable of producing to pass thru the next chain :) Until the input of your recorders 2.2uf caps block it all out anyway lol... Well I use 10uf because I dont want a battery box or preamp to filter out low end. That's my thinking...
Chris
for warranty returns email me at
EMAIL Sales@church-audio.com

Offline brn2rn

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Re: 3 wire bass rolloff HELP PLEASE!
« Reply #10 on: April 26, 2007, 05:05:46 PM »
A really good way of thinking indeed!

Do you have any recomended caps for that use.
The 2.2 ones I used the last time was roughly 35*20*8mm Polyester caps.
I´d like to find caps as small as possible, but 10uF would of course be a lot bigger?

Would this one be any good?
http://www.elfa.se/elfa-bin/inforuta.pl?textfield=6522908

Thanks,
Thomas
« Last Edit: April 26, 2007, 05:18:17 PM by brn2rn »

 

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