seas woofers and vifa tweeters, attenuate tweeter?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
So I'm thinking of using two Seas H1224-08 woofers with on vifa XT25C90-04 tweeter in this crossover: ImageShack® - Online Photo and Video Hosting I believe the crossover between the tweeter and the woofers is around 1000 hz, so that should work out well. My concern is that the sensitivity of the tweeter is at 91.7 db and the sensitivity of the woofers is 88 db. Is it necessary to attenuate the tweeter? How would I go about that?
 
Hmmm.....

Its a long time time since I've come across such a stunningly bad plan.

That x/o is terrible. The drivers are OK but need to be used in a properly
designed speaker or otherwise they will sound far worse than their
capabilities, and I suspect such design skills are not available.

Zaph|Audio
Is a good design and uses the H1224 properly.

It needs good design skills to build a proper 2.5 way using those drivers.
According to Zaph|Audio that tweeter is not ideally
suited to the low x/o point needed for the L18 driver.

rgds, sreten.


undefinition (see if nothing else, the excellent FAQs)
The Speaker Building Bible - Thread opened for edits/input. - Techtalk Speaker Building, Audio, Video, and Electronics Customer Discussion Forum From Parts-Express.com
Zaph|Audio
Zaph|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter
http://audio.claub.net/Simple Loudspeaker Design ver2.pdf
FRD Consortium tools guide
Designing Crossovers with Software Only
RJB Audio Projects
Jay's DIY Loudspeaker Projects
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
A Speaker project
DIY Loudspeaker Projects Troels Gravesen
Humble Homemade Hifi
Quarter Wavelength Loudspeaker Design
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
Linkwitz Lab - Loudspeaker Design
Music and Design
 
Tmi. I dont have a degree in electrical engineering. Just a what my punch-card computer designing father taught me growing up. It might help if I mention that the enclosure Im thinking of is a 0.8 cu ft ported with polyfill and one tapered 3" port with 1.75" diameter.
 
Tmi. I dont have a degree in electrical engineering. Just a what my punch-card
computer designing father taught me growing up. It might help if I mention that
the enclosure Im thinking of is a 0.8 cu ft ported with polyfill and one tapered
3" port with 1.75" diameter.

Hi,

0.8 cuft vented will work with two L18's but somewhat bigger is a little better.
Still your heading towards a very poor speaker if you don't design it properly.

The planned x/o is appalling bad, totally wrong, and will sound hideous.

A very sad fate for $400 worth of very good (used properly) bass/mid units.

rgds, sreten.
 
Last edited:
Much better than the bose crossover! Still, I think it's too low for that tweeter. You should try again with atleast 2khz, 4th order.

Can you post some more screen shots of components you are using for the woofer and tweeter in PCD, phase etc? Did you model the baffle step and diffraction for the drivers?
 
Last edited:
Hi,

As Zaphs x/o is near 4th order L/R acoustic at 2KHz, (its slightly asymmetric
to make the vertical dispersion more symmetric), a good idea would be to use
the low pass section as is and modify the high pass to suit.
Hard to think of a better topology you could use. Electrically the high pass
is second order and the low pass is a 3rd order elliptical (Caeur) filter.

Seas
Seas_27TBFCG-FR.gif


Vifa
Vifa_XT25SC50-FR.gif


The more extended low response of the Vifa needs a lower Q 2nd electrical filter
and you'll probably have to shift the electrical x/o point higher for the same target.
The L-pad for both is similar, perhaps R9=4.7R for the Vifa.
You may have to add a tweeter impedance peak compensation circuit.

Vifa distortion
Vifa_XT25SC50-HD.gif


You should be OK with 4th order L/R @ 2KHz. Clearly trying to
go lower than 2KHz with this tweeter is counter productive.


rgds, sreten.

For info here is the Seas distortion
Seas_27TBFCG-HD.gif
 
Last edited:
The low pass was designed for bose 6.5" woofers, not the Seas. I thought that I could still use it before I learned more about how crossovers operate. (thanks for the links guys, I learned alot.) If I could get some more advice on why and how it needs improvements (in layman's terms please. Sreten I appreciate the help, but don't know enough yet to understand.) Also, what's baffle step defraction and how and why do I need to model it?
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.