8 inch woofer for WAW

[planet10]

How long is a wavelength at about 800-900 Hz? ..and a quarter of that distance?

Usually this subject is in the FR forum where the acronym is well known, widely used, and discussed prior to inception.

Quarterwace length is about 4-6"

Typically the XO is more like 200-450 Hz.

dave

 

[ScottG]

Quarterwave length is about 4-6"

Typically the XO is more like 200-450 Hz.

dave

-and for something (1.5"-2") with a crossover around 800-900 Hz it should work out well, yes? (..provided the larger "fullrange"/midrange driver isn't to large and is placed next to the 1.5"-2".)

-yes, something nearing 200-450 hz for the high-pass (presumably active based on the OP's comments) for the "fullrange"/midrange.

 

[Cerniu]

If the baffle is narrow, that's going to lead to a lot of midrange "boost" or spl-loss at higher freq.s (for baffle-step compensation).

I'd actually suggest making it a 3-way and use a 2" or 1.5" for the treble (with it's less directive results) and a more efficient midrange driver for the pressure loss. 1st order transition for the 1.5" to efficent midrange with active high-pass on the midrange, and active for the bass.

Timothy Feleppa's Pages

As I am going active, what about that:
Lets say I make the baffle width 35cm. Then the baffle step frequency is 320Hz which is at crossover point and I solve the issue simply by attenuating the signal level in that crossover?

Usually this subject is in the FR forum where the acronym is well known, widely used, and discussed prior to inception.

Quarterwace length is about 4-6"

Typically the XO is more like 200-450 Hz.

dave

If moving to FR forum would spark less debate over the acronym we could move this thread.

 

[scottjoplin]

Seriously, most of this thread is wtf posts. Acronym's are best avoided, not sought out.

You appear to have no problem with TLA (Three letter abbreviations) shall we call WAW a TLA? (it would perhaps be more accurate)

 

[twocents]

Dr. Griesinger's research demonstrated that 700-7000Hz is the critical range of frequencies where our hearing and our brain combine the fundamental sound with its harmonics. According to Griesinger, we detect pitch more on the higher harmonics than we do on the fundamental. One of the main benefits of adding a small diameter full range is to cover the critical 700-7000Hz, and then accept the best extension near 20kHz as possible. A 700Hz crossover also removes beaming and cone grunge from a 8"-12" sealed box woofer with -F3 ~50-40Hz .

Interesting, but 700Hz seems a pretty high crossover for WAW - is this a low pass for the woofer?

 

[ScottG]

As I am going active, what about that:
Lets say I make the baffle width 35cm. Then the baffle step frequency is 320Hz which is at crossover point and I solve the issue simply by attenuating the signal level in that crossover?

-use a diffraction simulator to see what sort of loss AND gain you are dealing with. (..I'm on a Linux system and no longer have access to that. )

It's simplistic, but gives a general idea:
Home of the Edge

For something much better:
Software

I do know though that from that size width you are looking at some GAIN around 1 kHz, which can make the transition to the fullrange driver a bit tricky if it doesn't have a rise in response a few hundered Hz above that (and then flatten's out to 20 kHz). (..I'm assuming round-over baffle edges.)

Remember though, as you go to a larger diameter: the dispersion in the top-octave degrades quickly - "beaming".


Though not the Visaton, the MCM 3.5" (similar diameter) looks like this in the top octave (looking at 4 khz and up):

http://feleppa.com.au/pics/speaker_imgs/plots/MCM55-5650_FreqResp.png

 

[Cerniu]

-use a diffraction simulator to see what sort of loss AND gain you are dealing with. (..I'm on a Linux system and no longer have access to that. )

It's simplistic, but gives a general idea:
Home of the Edge

For something much better:
Software

I do know though that from that size width you are looking at some GAIN around 1 kHz, which can make the transition to the fullrange driver a bit tricky if it doesn't have a rise in response a few hundered Hz above that (and then flatten's out to 20 kHz). (..I'm assuming round-over baffle edges.)

Remember though, as you go to a larger diameter: the dispersion in the top-octave degrades quickly - "beaming".


Though not the Visaton, the MCM 3.5" (similar diameter) looks like this in the top octave (looking at 4 khz and up):

http://feleppa.com.au/pics/speaker_imgs/plots/MCM55-5650_FreqResp.png

Thank you for the tips, will research that tomorow. By the way I am also using linux as my operating system, and all simulation programs are quite simple so they run perfectly on Wine. You should try that out.

 

[ScottG]

-I'm trying to do something with Linux and am pretty clueless.

http://www.diyaudio.com/forums/everything-else/323964-linux-woes-thread-split.html#post5463882

 

[jmansion]

I'd like to have f3 of 50Hz and would prefer to go sealed. Also I think I will go active and biamp.

Try Seas CA22 RN/X and some linkwitz transform? I think it hits about 55Hz in 31l.

The 23cm SB Acoustics drivers supposedly hit about 50Hz, they are supposed to be good value. Perhaps a little more costly than the Seas though.

 

[friendly1uk]

You appear to have no problem with TLA (Three letter abbreviations) shall we call WAW a TLA? (it would perhaps be more accurate)

Will you be quoting my post a third time? I only ask, as something a bit more on topic would be nice.

 

[scottjoplin]

It's quite apparent that WAW is no better

Is it? Nevermind

 

[Cerniu]

Fortunately, I have found a way to get RS225, for 130 euro per pair (from PE with shipping to Europe done by another company).

If anyone in Europe wants to buy from PartsExpress, you should check out shipzee.com
I'm not sure on conditions for other countries (its a Lithuanian company I think), but a pair of Dayton RS225 delivered to my home come + import tax + service totals 130 euro, compared to 200 which was the cheapest I could find from suppliers inside EU.