building high pass filter

nanok66 · 4th May 2012, 03:43 AM

Hello all,
I'm almost done building a talkbox for my keyboard rig. The one thing I haven't finished is making a high pass filter for the high frequency driver in the talkbox. First off, if anyone knows whether or not this is a good idea, your comments are welcome.. (aka do commercial talkboxes do this???)

I have found lots of info online how to make high pass filters, so let me cut to the chase - a 2nd order (12db/octave) high pass filter @ 500hz (for an 8ohm driver) is what I want to build. I found VERY different schematics for the "same" circuit, depending on what website I looked at.

Here is the parts express circuit: (I assume I could just use the top half for my driver)

and here is another design for the same thing:

Whoa!! Aside from the complexity of figuring out all the values that I would use to make mine cutoff at 500Hz for an 8ohm speaker, does it really need to be as complicated as the second diagram?? Any help is appreciated. Thanks.

system7 · 4th May 2012, 01:46 PM

Well, my friend, you should tell what drive units you are using and in what box, then it might be easier to give an opinion of what to do.

We are no good at divining problems, you see.

nanok66 · 5th May 2012, 12:34 AM

Alrighty, by drive unit I guess you mean what high frequency driver I'm using? I'm using a Selenium D200 phenolic driver. And by box I guess you mean what enclosure I'm using?? It's an open backed enclosure. Hope that helps.

Inductor · 5th May 2012, 02:25 PM

Quote:

Originally Posted by nanok66

I'm using a Selenium D200 phenolic driver.

If that's all you got?!
Maybe it's more of a mid frequency compression driver? Don't expect too much from it on a full range speaker or at high frequency with it's 25dB attenuation.

http://www.muzyczny.net/selenium/att..._attachment=52

Inductor · 02:54 PM

Use a 1,4 inch exit throat CD with matching horn.
ND1460A - HF Neodymium Driver
XT1464 Constant Coverage HF Horn

If choosing speaker drivers you have to go a long way before diy a crossover. Look here for combos.

nanok66 · 6th May 2012, 08:42 PM

Ok I'm sorry I've definitely confused everyone with this post. There will be NO horn, NO subwoofer, and NO crossover. It isn't a multi range speaker project. This seemed to be the only place in your forums that filters (or crossovers) were discussed. I really am only looking to make a high pass filter for a single driver.

Just to let you all know what a talkbox is - it just consists of a single mid-high frequency driver that does not connect to any type of horn, instead there is 6 foot long piece of plastic tubing that goes into my mouth so I can "talk", or form the notes I am playing thru my keyboard into more vocalesque sounds.

If I posted in the wrong place my bad I don't know where the best place to talk about high pass filter design (which is like a crossover only simpler, so I thought it would be easy for you guys to point me in the right direction)

So hopefully I cleared this all up. Any help is still appreciated.

Hentai · 6th May 2012, 09:36 PM

The talkboxes i've seen using 8 ohm cds had a single capacitor in series with the driver. The value ranged from 22uF to 12uF. I guess you should try it between these values to see what works better.

nanok66 · 7th May 2012, 10:07 PM

Sweet, that info really started to point me in the right direction. Yeah the parts express website recommended a 28uF cap for my driver so I'm glad to know I'm in the right ballpark. And I'll just go with a 1st order (6 dB/octave) filter cause its super simple to build and will let a bit more bass thru anyways. Thanks!

4th May 2012, 03:43 AM	#1
nanok66 diyAudio Member Join Date: Apr 2011	building high pass filter Hello all, I'm almost done building a talkbox for my keyboard rig. The one thing I haven't finished is making a high pass filter for the high frequency driver in the talkbox. First off, if anyone knows whether or not this is a good idea, your comments are welcome.. (aka do commercial talkboxes do this???) I have found lots of info online how to make high pass filters, so let me cut to the chase - a 2nd order (12db/octave) high pass filter @ 500hz (for an 8ohm driver) is what I want to build. I found VERY different schematics for the "same" circuit, depending on what website I looked at. Here is the parts express circuit: (I assume I could just use the top half for my driver) and here is another design for the same thing: Whoa!! Aside from the complexity of figuring out all the values that I would use to make mine cutoff at 500Hz for an 8ohm speaker, does it really need to be as complicated as the second diagram?? Any help is appreciated. Thanks.

4th May 2012, 01:46 PM	#2
system7 diyAudio Member Join Date: Aug 2008	Well, my friend, you should tell what drive units you are using and in what box, then it might be easier to give an opinion of what to do. We are no good at divining problems, you see. __________________ Good Night, and Good Luck. Best regards from Steve in Portsmouth, UK.

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5th May 2012, 12:34 AM	#3
nanok66 diyAudio Member Join Date: Apr 2011	Alrighty, by drive unit I guess you mean what high frequency driver I'm using? I'm using a Selenium D200 phenolic driver. And by box I guess you mean what enclosure I'm using?? It's an open backed enclosure. Hope that helps.

6th May 2012, 08:42 PM	#6
nanok66 diyAudio Member Join Date: Apr 2011	Ok I'm sorry I've definitely confused everyone with this post. There will be NO horn, NO subwoofer, and NO crossover. It isn't a multi range speaker project. This seemed to be the only place in your forums that filters (or crossovers) were discussed. I really am only looking to make a high pass filter for a single driver. Just to let you all know what a talkbox is - it just consists of a single mid-high frequency driver that does not connect to any type of horn, instead there is 6 foot long piece of plastic tubing that goes into my mouth so I can "talk", or form the notes I am playing thru my keyboard into more vocalesque sounds. If I posted in the wrong place my bad I don't know where the best place to talk about high pass filter design (which is like a crossover only simpler, so I thought it would be easy for you guys to point me in the right direction) So hopefully I cleared this all up. Any help is still appreciated.

6th May 2012, 09:36 PM	#7
Hentai diyAudio Member Join Date: Nov 2006	The talkboxes i've seen using 8 ohm cds had a single capacitor in series with the driver. The value ranged from 22uF to 12uF. I guess you should try it between these values to see what works better.

7th May 2012, 10:07 PM	#8
nanok66 diyAudio Member Join Date: Apr 2011	Sweet, that info really started to point me in the right direction. Yeah the parts express website recommended a 28uF cap for my driver so I'm glad to know I'm in the right ballpark. And I'll just go with a 1st order (6 dB/octave) filter cause its super simple to build and will let a bit more bass thru anyways. Thanks!