Fast 6.5" woofer advise

Hi everyone,
I am building a 2 way speaker, using an ATD ribbon tweeter and a Audax hm 170 Z0 woofer.Unfortunatly this woofer was
substituted by the new HM170Z18, whose sensitivity is too low to match the tweeter (92 db).
My 2 new candidates are: SEAS H352 (P17RCY) and
Davis 17klv6a:

What I am looking for is a 6.5" woofer with at least 90 db sensitivity, frequency response till 3000 Hz, very fast impulse response.
It will be used in a vented B4 box.

Does anybody has suggestions, experiences to give me?

Thanks all.
The Audax HM170Z18 sounds a bit better than its predecessor and has pretty much similar specs.
His SPL is 89.5db /W/m (here the datasheets differ slightly).
Woofers are often less sensitive than the associated or designated tweeters, that is why we use resistors or Lpads and the like to attenuate the tweeters slightly. This is a very common thing.
What is your problem ?
I am contrary in using a resistor or Lpad to attenuate the tweeter: it adds unwanted sound; besides why waiste sensitivity if we can use it?

I checked on Focal drives, but I haven't found any woofer with a minimum 90 db sensitivity (2.8 V / 1 m).

I have heard good things on Seas P17RCY, but I don't know how is the time response or transient response: no data sheet info on this. Anybody knows about it?

And about the Davis, never used it?


2002-03-01 2:51 am
I've not built anything yet, and still learning, so may be way
off base. But, I've been looking at the PHL 1220 which has
a 93 SPL ([email protected]). It's a 6.5 paper which I read somewhere
was getting popular. The problem is that it looks like
it doesn't get below 100Hz when I plot it out, and I was hoping
for a bit lower than that. All in all, though..first speaker I tried
putting my own specs into the program, so I might have done
it all wrong.

6.5" HS Woofers


Personally i'am charmed of the Vifa units. Maybe the
Vifa 17WN 225-8 is a speaker you can use. It's relatively cheap about $90. It's usable up to 3000 Hz. A f3 of 45 [hz] is possible in a 20 to 25 liter reflexenclosure. SPL round about 91 [db].
Have a look at the speakers :
Seas WP 171NP , WP 171 or WP PPI

But, if you can't find a single driver that meets your specs, why not use two in parallel. This can boost-up your SPL between 5 en 6 db. Big advantage is your cone excursion by half.
Or even a push pull config.
These configurations allow you to surch for a speaker that gives you a good bandwith. E.g. the Visaton AL170 might be perfect for you. Two in parallel with a f3 of 35 [Hz] (40 liters, reflex) is possible. This speaker is usable up to 3000 [hz] and has a good impulse behavior.

Good Luck with your design

I checked on Vifa site, but I couldn't find the 17 WN 225/8.
His cone is made of what?

About the Seas, the one I put my eyes on (H352 P17RCY), is the same you wrote.My only doubt on it is the time response, or transient response: I couldn't find any diagram on it.

I am concerned about the sound of the drive too: technical data could be fantastic, but the sound is horrible; do you know how is the sound of the Seas?

About using 2 woofer it is a possibility, but I prefer spending more money on 1 good woofer instead of using 2 medium one's.
Maybe with a ribbon tweeter it is a better option, cause of the kind of ribbon dispersion.

I was thinking at double coil woofer too, but I never used one: any experince done?

About the Davis, anybody has ever used one?

I gathered some info for you about the Vifa.(See attached fig)
Re = 5.68 Ohm
Z = 8 Ohm
Fs = 47.6 Hz
Qms = 2.36
Qes = 0.44
Qts = 0.37
Vas = 24 liters
Mms = 13.8 Grams
Sd = 145 cm2
Cms = 0.81 mm/N
Rms = 1.869 kg/s
No = 0.57%
BxL = 6.99 Tm

I do not know the sound of any seas speakers. This was mere a tech spec. search.

About the use of two speakers instead of One. I’m not suggesting that you should use a lesser quality of speaker. I’m just saying that if you keep up you spec limit of 91 db your amout of suitable speakers will decrease dramatically. If you looking for a good/excellent speaker with 88/89 SPL levels you’re more likely to succeed.(Ofcourse used in parallel/pus-pull)

I’m not sure why you a willing too use a dual voice coil speaker. It does not boost-up you SPL level ythe way you want it. The only two reasons why I would buy a dual vc is :
1) For use in a stereo drivin subwoofer in a single enclosure,
2) For use in a two way system to boost-up the low frequenties.
Maybe you can elaborate more on this subject.



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the SEAS H624 has a paper cone, and paper doesn't have a fast response: that's why I suggested a choose between kevlar or poly woofers.

I checked on Vifa site, but I couldn't find the 17 WN 225/8.
The specs you posted seems good, but I think the model you suggested is no more produced by Vifa.

Actually I am looking at the specs of the Focal 7K4412.
Seems it should work out !