TB W5-1138SMF in 2-way (not FAST)

[jbarelds]

I intend to build a speaker. My design goals are:
1. Small cabinet (5 ... 10L)
2. Good bass
3. Good off-axis performance in the higher frequencies

I know it'll never be a very sensitive speaker, considering my first two design goals. I already built a FAST speaker before, using two Visaton W 130 X's and a Dayton PS95. It sounds quite nice, as long as you sit right in front of it. Off axis response is not great.

However, because of my past experience with the PS95, I'd like to use a dome tweeter instead. The W5-1138SMF's rated usable frequency range is up to 1500Hz. Looking at it's SPL graph, this is about where cone breakup starts to be an issue. I'm thinking about combining it with a dome tweeter thats usable from a relatively low frequency. Something like the Dayton DC28F. It's rated range is from 1.3k (I know a full octave above fr is advised, for the DC28F 1.3k is only just above half an octave).

My main question is: would you think the W5-1138SMF is usable for midrange (as in: sound good) up to around 1.5kHz?

 

[Cal Weldon]

I would say no, pick a more suitable woofer. The 1138 is trying its hardest to be a subwoofer and while the bass can be impressive, it really requires it's own amp. I've used the big brother the 1139 in a few designs and have been unable to do anything good with it as a regular woofer.

 

[chris661]

You want to cross over at about 1kHz, maybe lower.

Here are the options:
- A super-expensive 1" dome tweeter
- 1.5" dome tweeter
- A small (2") full-range speaker
- Compression driver + horn.


FWIW, for your application, I'd be looking at a 2" full-range driver. SB Acoustics do a 2.5" one that's pretty cheap and is supposed to sound good.

I've used the W6-1139 with a full-range driver and it worked pretty well. My current 2-way speakers have a crossover at 900Hz, and use a Seas 8" aluminium coned midbass, and a 1" exit compression driver. The crossover is non-trivial, but works well.

Chris

 

[jbarelds]

Thanks for the feedback. Unfortunately you two confirm my worries about the midrange capability of the TB driver. I think I’ll make it a 3-way after all. I think I’ll use a plate amp (with low pass) for the 1138, and a passsive 2-way xo for mid and high (maybe with an additional high pass for the mid).

 

[TBTL]

You might want to measure the woofers before deciding on the crossover point. The W5-1138sm I have does not exactly match the spec sheet. I measured the first cone resonance to occur at 1 kHz, not at 1.5 kHz.


When the crossover is a DSP, there is no need to cross at twice the resonance frequency of the dome tweeter. Its impedance is not relevant any more, but its harmonic distortion will determine the lowest possible crossover frequency.