Coax vs WAW

[PeteMcK]

One of these:
SB Acoustics :: 5" SB13PFC25-4-COAX
vs: these together:
5" SB13PFC25-4 :: SB Acoustics plus
TG9FD10-04 - VIFA 31/2" Full Range - Vifa

pros/cons?

 

[ErnieM]

Coax woofer will modulate the treble if used as a 2-way.

The Vifa looks very nice. Easy cross at 400hz. Still have a point source, more woofer output without muddying up mids and treble.

 

[AllenB]

Have you decided where you'll cross? Are you aiming for something smooth on axis or are you thinking about directivity as well?

 

[PeteMcK]

Re:'Coax woofer will modulate the treble" - good point Ernie;
Re:'Have you decided where you'll cross?" _ Hi Allen, no, just mulling over the pros & cons of the two approaches, directivity is important. I think with current tech., the WAW will win out...

 

[rabbitz]

The TG9FD10-04 is a nice FR driver but I've only ever used it as a single unassisted.

I did look at using a SB coax but the crossover put me off as well as I don't think the tweeter would be a good performer.

http://www.sbacoustics.com/index.php/download_file/-/view/1458/

 

[AllenB]

Coax may not be perfect, but has pros. The woofer doesn't play through breakup, and the physical cross is clean.

Then there is the potential constant directivity of the treble offered by the cone. The full range driver will also have narrowing at the top. Which do you prefer, your choice.

The 3.5" might have its breakup low enough to be a problem. At least that is my experience with some 3.5" full range drivers but, if you pick the right one this may not be an issue. Smaller is another option.

 

[chris661]

I'd go for a best-of-both and get a smallish coaxial with LF support.

Chris

 

[scottjoplin]

To my mind, WAW uses a larger woofer crossed as low as you can go.

 

[andy19191]

Can I ask why it is coax vs wideband+midwoofer rather than coax vs tweeter+midwoofer which would seem a more natural comparison?

 

[phivates]

It's a format choice. XO at 400 or 4000, more or less, and off axis behavior.

 

[andy19191]

It's a format choice. XO at 400 or 4000, more or less, and off axis behavior.

The off-axis behaviour of a wide band driver could be considered superior to that of a coaxial?

Is the ragged transfer function due to strong resonant behaviour weighted as a significant disadvantage?

Why could a crossover at 400 Hz be considered better than one at 4000 Hz?

(I am not disagreeing with a choice of a wideband driver I just don't understand the set of design choices that leads to one being specified.)

 

[silverprout]

The listening distance should be the first thing to consider for that kind of dilemma, no?

 

[PeteMcK]

Thanks for all the input guys.
I'm thinking that crossing low would give better suppression of the midwoof breakup, but leave you playing through the widerangers breakup. The low xover would be easier to implement, and I've never seen coax measurements that had a particularly flat response in the upper region.
Having heard only one coax, and that some time ago, I'm not sure if the co-incidence 'magic' would be any better with a co-ax vs a wideranger.
cheers

 

[phivates]

Different not better. The wide band driver will have narrowing dispersion at a lower frequency than the small tweeter on the (intriguing) coaxial, but the mid cone on the coax is probably narrowing at the top of its range before crossing to the tweeter. Build both and report please - I have a KEF Q-70 pair that needs a new coaxial since they stopped supporting old models needing new tweeters. SBA has a crossover schematic for them.

 

[Patrick Bateman]

One of these:
SB Acoustics :: 5" SB13PFC25-4-COAX
vs: these together:
5" SB13PFC25-4 :: SB Acoustics plus
TG9FD10-04 - VIFA 31/2" Full Range - Vifa

pros/cons?

My current project offers what you're looking for (good phase response, point source behavior) without the drawbacks of a coax:

"Unitized" Image Control Waveguide

Footprint should be fairly similar.

 

[AllenB]

I'm not sure if the co-incidence 'magic' would be any better with a co-ax vs a wideranger.

A crossover can succeed despite physical displacement, if you design accordingly. Therefore, this particular magic may be easier to find with a coax, but it isn't limited to a coax.

playing through the widerangers breakup.

The last time I bought a fullrange driver I took advice from Planet10, and I wasn't disappointed. IIRC he is now using a smaller 2.5"-3" unit that is supposed to have a good top end.

 

[AllenB]

Why could a crossover at 400 Hz be considered better than one at 4000 Hz?

When done properly there won't be a difference of course. But 400Hz is slightly harder to mess up, say if either there is a minor acoustic issue, or to avoid going through a rigorous design process.