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-   -   1" full range high pass newbie question (http://www.diyaudio.com/forums/full-range/186163-1-full-range-high-pass-newbie-question.html)

troglodyte 31st March 2011 03:23 PM

1" full range high pass newbie question
 
I'm creating some 1" full range speakers with the hi-vi b1s that I bought from madisound

I'm using the sure electronics 2x2w amp from parts-express

I was thinking of adding a high pass filter to it since it wouldn't hit below 270hz (or would you aim for a different frequency?) but would it worth it or effective - not really sure since this is my first speaker build (newbie)

I used this first order calculator here and if i'm understanding this right, I would be using a cap inline from the positive site of 73.61111111111111 (i'm sure i'll find a cap that matches that exactly lol)

just looking for advice on the setup - many thanks!

Cal Weldon 31st March 2011 04:30 PM

It's difficult to XO near the resonant frequency as the impedance spike can throw you off so I would recommend running them straight or do the XO above or below the Fs where the impedance is a little more reasonable.

troglodyte 31st March 2011 05:15 PM

https://www.madisound.com/catalog/im...ges/b1s-zm.jpg

Thanks for the reply. So according to this chart I see the spike I think you're talking about. So I would want to shoot for something in the 100hz range? Or were you talking about something else?

I wonder if it would be of any benefit?

Cal Weldon 1st April 2011 02:40 AM

If you do it below it will act as a bit of protection, if you do it above you will get protection and a noticeable attenuation of the lower end.

godfrey 1st April 2011 03:46 AM

If you're just using a series capacitor then going higher e.g. to 500hZ is a bad idea. Response will roll off below 500Hz, but you'll get a big peak in output again at about 250Hz where the speaker impedance goes up to nearly 30 ohms.

It would be better and cheaper to put a filter at the input of the amp. Then you don't have to worry about interaction of the cap and speaker impedance.
:2c:

borispm 1st April 2011 10:39 AM

With this driver, I think you can try a steeper high pass, say a forth order. You can cross closer to the fs, say 350Hz.

Buckapound 1st April 2011 11:39 AM

You might put the cap on the input side, or rather replace the existing input caps (most of those class D boards have them) with lower value caps. This will relieve the amp of spending energy creating frequencies that will not be used, so the thing should work more efficiently and louder. I'm guessing the value will probably be somewhere around 0.2uf or so; somebody with the formula handy could probably calculate it, but it's also easy to try different values until it sounds right.

--Buckapound

enigmaticEntity. 1st April 2011 04:06 PM

This written by Zaph at Zaph Audio about the b1s

Comments: This is a very different driver. Much smaller than the average tweeter, but clearly designed to be used lower in frequency and at lower levels. As such, I've supplied a harmonic distortion curve here, taken at a level 10dB lower than normal. The rear chamber for this is critical, and must be shaped as described here for the best effect: drill a 1-1/4" hole through 3/4" MDF. Then round over the back side with a 1/2" roundover bit. Finally, densly stuff that area with Acousti-stuf and glue another board over it to seal, while allowing holes for the wires to pass though. It took experimentation to get this response, and without it the response curve was terrible. Tested January 2007.

This should help it sound a bit nicer. I haven't heard this driver though, so I can't say if the "terrible" response curve sounds good or bad. Makes for a really tiny enclosure! :)

maduras 1st April 2011 05:09 PM

This driver will disappoint you.I ones tried to use 72 of them in a array because of the low Fs.They sound grose even 72 of them together.
Gave them away to someone.

borispm 2nd April 2011 02:52 AM

It's all about gives and takes. With such a small driver, you can build an array that images like hell, but you have to add a woofer to that, maybe crossed at 300-400Hz will do. Remember to seal the driver chambers properly and stuff them though. No matter how many of these drivers you are using, you will probably never get usable output below 200Hz without heavy distortion.


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