Suitable Tweeter for Fountek FW146 5.5"

[haryojo]

Hi dear
I want to build a 2 way bookshelf speaker with an existing driver: Fountek FW146 5.5 "Aluminum Cone Woofer. but, the tweeter not ready. Does any one can help me, which tweeter to match the woofer . tks all

 

[tuxedocivic]

Depends on your objectives. I'd probably use a small dome neo like the sb29rdcn

 

[Bob Richards]

The trouble with metal cone woofers is that they have severe resonance, usually in the upper midrange, right where the ear is most sensitive. So high order crossovers are usually necessary, to attenuate energy any where near that frequency, or using a very low frequency crossover point.

 

[ScottG]

The Fountek FW146 has "peaking" of about 10 db at 10 kHz. The good news however is that it's NOT a resonance, it's just more efficient at the top of it's passband.

http://techtalk.parts-express.com/attachment.php?attachmentid=6341&d=1263085287

It is however a 5.5" driver - so its off-axis performance (with its phase-plug) will start becoming a problem a bit above 2 kHz.

So there is a choice to make here:

1. let it run nearly full-range with a correction filter and a tweeter crossed over high that has limited dispersion, OR

2. crossover low with a more "robust" tweeter allowing for greater horizontal dispersion.


For #1:

Products_Fountek Electronics Co.,Ltd

or

H1499-06 27TBCD/GB-DXT


for #2:

Trans Lab, N26C-X



Both solutions will need higher order crossovers. The easier solution will be the second because it will require less work with the crossover.

 

[joern]

Hi

here ist a nice fit:
Skunk - DIY-HIFI-Forum
try some google translater from german to your language.

 

[sreten]

The good news however is that it's NOT a resonance,
it's just more efficient at the top of it's passband.

Hi,

Not true. It is metal cone breakup and a too high
crossover will have poor distortion performance.

Zaph|Audio

Shows one way of dealing with it, but needs
careful design to hit the target acoustic slopes.

rgds, sreten.

 

[6.283]

Hi,

Not true. It is metal cone breakup and a too high
crossover will have poor distortion performance.

Zaph|Audio

Shows one way of dealing with it, but needs
careful design to hit the target acoustic slopes.

rgds, sreten.

Hi sreten,

the FW 146 is, however, much better than the Seas in this respect. I did not believe it myself but our two German DIY speaker magazines have reviewed and measured it (one with Clio and one with MLSSA) and there are virtually ZERO distortion issues from break up. In total, distortion (as measured by these two systems) is very low. Quite amazing for the price tag (or the wrong excitation signal but that would be another discussion).

However, I believe it starts beaming pretty early for a 5". So that would be the reason why I would cross rather low to a tweeter (in order to match the directivity).

 

[6.283]

However, I believe it starts beaming pretty early for a 5". So that would be the reason why I would cross rather low to a tweeter (in order to match the directivity).

Or use a tweeter in a waveguide like this

Waveguide WG 148 R

or this

H1499-06 27TBCD/GB-DXT

 

[ScottG]

Hi,

Not true. It is metal cone breakup and a too high
crossover will have poor distortion performance.



rgds, sreten.

Its behavior is still quite linear (as shown in the CSD). This is NOT break-up as in a traditional lack of mass control, or "bell" mode resonance.

Its non-linear behavior also shows no significant effect other than a boost in 2nd order distortion commensurate with the elevation in spl as it becomes more efficient:

http://techtalk.parts-express.com/attachment.php?attachmentid=6381&d=1263263086

 

[sreten]

Hi,

The SPL boosts effects on distortion for metal driver peaks are well known,
and inevitable, even if absolute level is acceptable, the effect is still there.

I don't really want to argue about what the large top end peak is,
to a degree, what you think it is will decide your approach to it.

I like the elliptical / Caeur approach, usually a 1st order baffle step inductor
followed by a second order notch filter, tuned to the peak, and Q carefully
arranged to create the right acoustic slope around the crossover region.
Requires careful design and might turn out not to be the right approach.

rgds, sreten.

Its a monster of a peak at the top end, around one particular frequency,
so ideally suited to Zaphs strategy as outlined by him in the article :

 

[ScottG]

Yup. "Tomato or Tom(a)to", that peak still needs to be addressed.

The only real difference is that, accepting pressure loss off-axis as freq.s increase, it could be used fullrange once corrected (..assuming it's properly corrected for that application).

Still,

Because of the problems with dispersion and the higher freq. peaking - a solution like Zaph's seems to be preferable.