# T/S Parameters Test Bin



## cvjoint (Mar 10, 2006)

Test machine WT3. Only tweeters for now as I have not figured out the VAS method yet. 

I encourage everybody to post up T/S parameters on drivers they have. I find they are quite a bit different at times from the manufacturer's white sheet. Some don't even have a complete listing of specs! 

Vifa NE19VTS-04
* f(s)= 785.30 Hz
* R(e)= 2.71 Ohms
* Z(max)= 10.31 Ohms
* Q(ms)= 4.946
* Q(es)= 1.763
* Q(ts)= 1.300
* L(e)= 0.00 mH

SB SB29RDCN-C000-4 left:
* f(s)= 723.40 Hz
* R(e)= 3.02 Ohms
* Z(max)= 6.54 Ohms
* Q(ms)= 1.025
* Q(es)= 0.880
* Q(ts)= 0.474
* L(e)= 0.00 mH
SB SB29RDCN-C000-4 right:
* f(s)= 714.60 Hz
* R(e)= 3.04 Ohms
* Z(max)= 6.71 Ohms
* Q(ms)= 1.082
* Q(es)= 0.896
* Q(ts)= 0.490
* L(e)= 0.00

Vifa XT25SC90-04 left:
* f(s)= 814.20 Hz
* R(e)= 3.16 Ohms
* Z(max)= 26.21 Ohms
* Q(ms)= 7.876
* Q(es)= 1.080
* Q(ts)= 0.95
* L(e)= 0.04 mH
Vifa XT25SC90-04 right:
* f(s)= 833.70 Hz
* R(e)= 3.14 Ohms
* Z(max)= 24.50 Ohms
* Q(ms)= 7.350
* Q(es)= 1.080
* Q(ts)= 0.942
* L(e)= 0.05 mH

BG Neo 8 left
* f(s)= 343.90 Hz
* R(e)= 3.46 Ohms
* Z(max)= 3.69 Ohms
* Q(ms)= 3.221
* Q(es)= 47.160
* Q(ts)= 3.015
* L(e)= 0.00 mH
BG Neo 8 right
* f(s)= 321.70 Hz
* R(e)= 3.60 Ohms
* Z(max)= 3.82 Ohms
* Q(ms)= 2.951
* Q(es)= 47.980
* Q(ts)= 2.780
* L(e)= 0.00 mH

Dayton Pt2b8 left
* f(s)= 2646.00 Hz
* R(e)= 6.61 Ohms
* Z(max)= 6.95 Ohms
* Q(ms)= 1.333
* Q(es)= 26.340
* Q(ts)= 1.269
* L(e)= 0.00 mH
Dayton Pt2b8 right
* f(s)= 2694.00 Hz
* R(e)= 6.73 Ohms
* Z(max)= 6.96 Ohms
* Q(ms)= 0.138
* Q(es)= 4.202
* Q(ts)= 0.134
* L(e)= 0.00 mH

Be cautions in interpreting the results for planar tweeters as their impedance peak is almost nonexistent.


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## ErinH (Feb 14, 2007)

Cool thread. Sub'd.

Think you could post up impedance plots as well?
Regarding the Vas method, feel free to give me a call and I can tell you what method(s) I use for finding Bl/mms/Vas, etc. 



just a heads up to anyone posting driver results...

for woofers/smaller drivers with pole vents, make sure to NOT block the pole vent. this will screw up the results. 


Also, make sure to tell us how the driver was mounted or if it was true free-air. These things effect the results as well.


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## cvjoint (Mar 10, 2006)

I'll have to do my own homework first on what method may be workable and how to clamp down the drivers. I just tested my tweeters for now as they don't hinge on being clamped down, would be nice to get the rest of the parameters though. 

The WT3 doesn't seem to have a graph export tab. I would have to use print screen on it. That would add to the time required quite a bit. I still have to plug in the WT2.


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## ErinH (Feb 14, 2007)

trust me, I know about the time thing... sucks.

re: clamping the drivers down:
woofertester.com


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## cvjoint (Mar 10, 2006)

bikinpunk said:


> trust me, I know about the time thing... sucks.
> 
> re: clamping the drivers down:
> woofertester.com


Genius! I totally dig this method and it saves me time and thinking. I'm going to hang mine from the LCD wall mount!

Since you are so resourceful with this stuff  I don't want to build a box everytime for VAS, is the added mass method the one to go for?


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## ErinH (Feb 14, 2007)

IMO (_IMO_), added mass is good for larger drivers... say 6" and up. Really, though, if it's not a driver 10" or larger, it gets tested in the sealed box. I feel that's more accurate because the mass added needs to be hefty enough to make a difference and I don't feel like messing with a nice cone or trying to get the spacing just right (an offset can mar results)... plus, to me, it's a ratio of mass added vs. cone mass. If the ratio is low, I feel like the added mass might be too much of an error point. Know what I mean?

So, I have a 1.125 ft^3 box and a few blanks (that I used for my FR testing and now just use generically) to attach drivers to, then clamp them down to the box and run the sweep. It's actually really quick, easy, and doesn't leave gummy residue on someone else's speaker. 

Here's a picture of the box w/toggle clamps I got from Harbor Freight:


Really, any old box will do. You may want to have something to fill the box with, though, if it's too large for smaller driver testing (ie: 2-3"). I noticed that sometimes the data doesn't resolve well when the box size is that much larger than the driver tested. So, I take a brick, put it in the enclosure, and reduce that volume from the box volume. Good to go. :thumbsup:




bikinpunk said:


> test box for Vas method of sensitivity, Vas, Bl, compliance, etc measurements is built! First test proved to be very fruitful.
> 
> All drivers larger than 8" will have to be tested via the added mass method, but for all drivers equal to or smaller than 8" a sealed box of 1.125ft^3 will be used. My first measurements of the Scanspeak 18w/4ohm put the sensitivity right where it should be, based on mfg spec: 88dB @ 1w/1m.
> 
> I took an old subwoofer test box I had, added a couple scrap pieces of MDF to the top and used some toggle clamps purchased from Harbor Freight to clamp the baffle inserts on to the test box. Very simple but effective.



*ps: strips of weather foam around the edge of the driver mount helps seal it all up


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## cvjoint (Mar 10, 2006)

bikinpunk said:


> IMO (_IMO_), added mass is good for larger drivers... say 6" and up. Really, though, if it's not a driver 10" or larger, it gets tested in the sealed box. I feel that's more accurate because the mass added needs to be hefty enough to make a difference and I don't feel like messing with a nice cone or trying to get the spacing just right (an offset can mar results)... plus, to me, it's a ratio of mass added vs. cone mass. If the ratio is low, I feel like the added mass might be too much of an error point. Know what I mean?
> 
> So, I have a 1.125 ft^3 box and a few blanks (that I used for my FR testing and now just use generically) to attach drivers to, then clamp them down to the box and run the sweep. It's actually really quick, easy, and doesn't leave gummy residue on someone else's speaker.
> 
> ...


Yeah, I remember this sexy beast. Since you are doing at least 3 types of testing you kind of get increasing marginal returns to making a baffle. To me the costs are high. At least I know what I'm missing. 

Well, I think I'll try the mass method just due to cost constraints. However, I'll try hard to spread the mass evenly. My WT3 came with a precision scale. I'll use that to find sets of 4 coins for every major MMS threshold. I'm thinking some very weak double sticky tape would be good enough to have them hang on a bit. They will kinda have to hang on by themselves with stationary phaseplug drivers. 

At least I know my CSS drivers are in good hands. I may use your T/S parameters to gauge how well I build my rig.


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## cvjoint (Mar 10, 2006)

I am realizing just how important the actual impedance curve is. Luckily the WT2 has an easy screen capture. Wherever you see little wiggles odds are there are some resonances and they generally show up in my distortion testing as either linear or nonlinear distortion or both. 

B&C 6ndl44 7" woofers


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