T-B W3-2141 measuring way off spec - anyone else used this driver?

[cjd]

Has anyone else worked with the T-B W3-2141?

Collaborating on a project and pulling some early data, and they seem to measure drastically different from published.
This is taped to the baffle not flush-mounted, so I'd expect a little diffraction but not the 10dB peak at ~2900Hz and the dip at 4k. Impedance changes shape like spec, but at ~3200 vs ~1600

Update: T/S parameters for the two drivers I've been measuring.

Loudspeaker parameters:

Fs = 124.79 Hz
Re = 7.10 ohm[dc]
Le = 55.99 uH
L2 = 340.99 uH
R2 = 4.47 ohm
Qt = 0.47
Qes = 0.65
Qms = 1.75
Mms = 1.82 grams
Rms = 0.814988 kg/s
Cms = 0.895738 mm/N
Vas = 1.15 liters
Sd= 30.19 cm^2
Bl = 3.956203 Tm
ETA = 0.33 %
Lp(2.83V/1m) = 87.83 dB

Added Mass - Constant Bl Method:
Driver unbaffled
Added mass = 3.20 grams
Membrane Diameter= 6.20 cm

Loudspeaker parameters:

Fs = 126.60 Hz
Re = 7.10 ohm[dc]
Le = 55.29 uH
L2 = 317.53 uH
R2 = 4.68 ohm
Qt = 0.43
Qes = 0.60
Qms = 1.52
Mms = 2.31 grams
Rms = 1.213469 kg/s
Cms = 0.683138 mm/N
Vas = 0.87 liters
Sd= 30.19 cm^2
Bl = 4.662416 Tm
ETA = 0.28 %
Lp(2.83V/1m) = 87.15 dB

Added Mass - Constant Bl Method:
Driver unbaffled
Added mass = 3.20 grams
Membrane Diameter= 6.20 cm

Really disappointing results.

C

[DeZZar]

I suppose you've already let them run in a little?

Did you already try it flush mounted?

You could always just measure the drivers out of the box purely to see if there is a difference?

[tvrgeek]

Manufactures specs are advertising.

[cjd]

I suppose you've already let them run in a little?

Did you already try it flush mounted?

You could always just measure the drivers out of the box purely to see if there is a difference?

This is my usual process, and I've never had anything measure this far off spec. Fs is usually higher and other little stuff. I even went back to re-measure stuff I've already done just to validate nothing went weird with my measurement rig.

I always do a few cycles just to see how things change for a driver. These have a little burn-in time on them, but they're now getting more. Also getting around to setting up a proper test baffle again where I'll flush-mount anything by making a new insert. Maybe this is something to do with the treated surround and it'll change more with break-in than I've seen before.

Waiting to do final cabinet work till I've settled on a driver for sure, as I have a few options still right now... that kinda goes away once I recess for flush-mounting.

Manufactures specs are advertising.

Yeah, and T-B is typically a little optimistic. I've used drivers from them before. But this seems wildly optimistic, or an indication of a problem in manufacturing which they haven't caught. Not sure yet, but that's why I stopped in to ask.

[Chris Roemer]

I know you're (primarily) looking at FR, but did you T/S parm your drivers (just curious)?

cjr

[cjd]

I know you're (primarily) looking at FR, but did you T/S parm your drivers (just curious)?

cjr

Nope. I have to reread the manual, don't remember a thing about doing that other than I hated it. Re sure looks to be higher than spec though...

[tvrgeek]

Do yourself a favor and get a DATS / WooferTester for TS parameters.

[cjd]

I'm guessing from the responses no one else really has experience with this driver.

Do yourself a favor and get a DATS / WooferTester for TS parameters.

I hate having to fiddle with adding mass or sorting box volume accurately... Not sure I vhave a way to do mass at the moment, either misplace or tossed when we moved a few years ago. Though I can still get free air data which would be useful in this instance. What's the latest DATS do which I don't already have tools to do?

Edit: actually should probably use taped weight here anyway to avoid staining. Hopefully that doesn't damage the cone...

[---k---]

Chris, you've been away too long that people don't know you. 😀

I once upon a time had a Woofer Tester (version 2 I think). I lent/gave it to someone, becuase I wasnt really ever going to use it. I don't remember who I gave it to. You'd be the most likely candidate. Maybe it was JonW?? You might dig through your boxes and see if it is in one. Don't know how useful it'd be to you, becuase I thought it took impedance real easy but still did the added mass method to get the full t/s. I don't really remember.

[PWR RYD]

Hi Chris, good to see you posting again. I haven't used that TB W3, but I have used several other of their drivers. None of them have measured very closely to the manufacturer's spec. Some have sounded fantastic though. Some just meh. Based on your measurements I'd move on and pick a different driver.

PS. are you still road racing/auto-crossing that little coupe?

[djg]

You don't know me, but we spoke at an Iowa DIY years ago. I'm building 3 of your RS150 MTMs, after picking up enough RS150S-8s. I hope they sound as good as your 3 way design at the DIY event. Build thread later this year when it warms up.

[cjd]

Chris, you've been away too long that people don't know you. 😀

I once upon a time had a Woofer Tester (version 2 I think). I lent/gave it to someone, becuase I wasnt really ever going to use it. I don't remember who I gave it to. You'd be the most likely candidate. Maybe it was JonW?? You might dig through your boxes and see if it is in one. Don't know how useful it'd be to you, becuase I thought it took impedance real easy but still did the added mass method to get the full t/s. I don't really remember.

Unfortunately I don't have your woofer tester! That would have been helpful just to triple check some of the data. Oh well. I'll get around to added mass - doesn't take much for these little drivers.
As for being away too long, maybe. I've also been away and forgotten some details, so don't object to the reminders.

Hi Chris, good to see you posting again. I haven't used that TB W3, but I have used several other of their drivers. None of them have measured very closely to the manufacturer's spec. Some have sounded fantastic though. Some just meh. Based on your measurements I'd move on and pick a different driver.

PS. are you still road racing/auto-crossing that little coupe?

Yeah, not entirely my choice in driver though. We'll see how this goes. I think they'd do fine as reasonably wideband mids even. Might be able to beat them into usable shape full-range, we'll see. Sometimes that's half the fun?
Also yeah, still racing a BRZ, though I'm on my second one. Codriver crashed the first one! Also not so much 2020, probably not 2021; I need to hide away till we're all vaccinated and stuff, so a lot more sim racing this year.

You don't know me, but we spoke at an Iowa DIY years ago. I'm building 3 of your RS150 MTMs, after picking up enough RS150S-8s. I hope they sound as good as your 3 way design at the DIY event. Build thread later this year when it warms up.

Did I do a version with the S-8? Ha. I don't recall that. I still have mine, and they still sound good. Different from the Nebbiolo in a lot of ways. I've actually tucked mine away lately. I should get them out! Anyhow, have fun with the build and I hope you enjoy.

[Wolf]

Good to see you pop in, Chris!
Wolf

[zx82net]

This is a gated measurement of a W3 2141 in a ~2.5l enclosure. I purchased the driver about 18months ago from PE.

[zx82net]

...And the baffle dimensions are about 13.5 x 16cm.