2-way journey with Seas W22EX

[Dumbass]

Yoga for Loudspeakers.

 

[Vikash]

ShibOBIWAN, did you measure the driver T/S by any chance?

This is what I'm getting:

Driver		Fs	VAS	Qms	Qes	Qts	
Specsheet	25	98	2.14	0.41	0.34
Measured A	30	68	3.04	0.50	0.43
Measured B	30	66	3.06	0.48	0.42

 

[ShinOBIWAN]

Seas data sheet suggest:

Fs: 25hz
VAS: 98 ltrs
QMS: 2.14
QES: 0.41
QTS: 0.34

So your not far off with the exception of VAS and QMS. I also measured the drivers after a 20hr run in and got similar results to the seas spec sheet using Audiotester and speakerworkshop. They only had around 30 hours tops when I sent them to you so they may need running in some more.

 

[Vikash]

I've hammered them for over 48 hours at high excursion. Those are my measurements afterwards.

I suppose I should see what the modelled differences are first between the specsheet and my measurements first. But I'm not happy with this. Why can't the flippin floppin measurements just be the same. Argh!

 

[ShinOBIWAN]

I've hammered them for over 48 hours at high excursion. Those are my measurements afterwards.

I suppose I should see what the modelled differences are first between the specsheet and my measurements first. But I'm not happy with this. Why can't the flippin floppin measurements just be the same. Argh!

The affected parameters only effect the high pass behaviour of the driver. I also assume your using the added mass method for VAS? If so you'll get better results using IB, its what I used and the VAS was pretty close to spec ~90ltr if I remember.

Also the measuring kit your using may or may not be accurate as we'd like. And finally it could be that Seas simply wasn't on the ball with this batch of drivers and they are out of spec.

At least the drivers are closely matched.

 

[Vikash]

Yes I used the added mass method. 47.1 grams. I also tried approx double that to check for difference and the VAS was almost identical.

As for measuring kit, I use SW and Wallin Jig V2. I like to think it's very accurate from the other tests I've done with it. But hey, who knows!

Thanks for your input.

 

[ShinOBIWAN]

Yes I used the added mass method. 47.1 grams. I also tried approx double that to check for difference and the VAS was almost identical.

As for measuring kit, I use SW and Wallin Jig V2. I like to think it's very accurate from the other tests I've done with it. But hey, who knows!

Thanks for your input.

It probably is accurate Vikash or certainly more accurate than my SW measurements were after comparing your resistor testing results to my own. Also you had very close correlation between the XLS10 measurement and manufacturer data.

The specs you've measured are most likely an accurate representation of the real specs. I wouldn't really count mine since the setups aren't comparable and the drivers only had around 20hrs run-in.

The most likely culprit is simply that Seas specs don't match that of the production drivers or at least in this case.

What really matters is the drivers are well match and in this case they are. The differences in the T/S are minor and the resulting high pass behavour is similar to the predicted response from the spec sheet. Personally when modelling the enclosure trust your specs more.

 

[Vikash]

Using the measured T/S params I think this is best set of compromises: ported 55 litre enclosure tuned to ~28Hz - which is pretty much what you said IIRC:

Not sure how to interpret the group delay graph. Any input would be appreciated.

Regarding my earlier T/S concerns, I just noticed that my measured params are virtually bang on to the W21EX001 specsheet. Surely not just a coincidence.

 

[ucla88]

Vikash,

I think those measurements are pretty good. IIRC, one of the Seas technician's described the TS measuring process on the MAD board a while back, which is a bit different than the typical small signal process that we all do. They think it more realistically reflects TS at typical drive levels. I guess that's debatable, but not really a reason to worry.

Remember, the whole TS thing is a linearized assumption of how a driver really works, so to speak. Different drive levels and test setups will give somewhat different results because of a real world driver's nonlinearity.

 

[audioholik]

if i have 2way setup with w22ex and accuton c44 2" ceramic tweeter.
are my 300B SET tube amp rated @8watts will be sufficient?
thanks