New Peerless STW350 subwoofer on the horizon...

Links are broken
http://www.tymphany.com/stw/

What a beast!!
188mm voice coil
And as a result, a tiny spider relative to the size of the driver :/

Inset motor designs from Morel and HiVi suffer from higher non-linear distortion at excursion compared to conventional motor designs with smaller diameter voicecoils and larger and more linear spiders. I don't hold high hopes for this design for that reason... Kind of pointless having 40mm xmax when the spider is only as linear as your average 8" woofer. Tymphany make some good drivers but this one seems like another "engineered by the marketing department" design.

edit: the actual one way xmax is 10.5mm, abysmal! http://www.tymphany.com/wp-content/themes/pathfinders/cache/pdfs/STW-350F188PR01-04.pdf
 
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TMM

Member
2007-09-01 8:37 am
Australia
VoiceCoil tested one of the Morel TiCW large woofers, and the HD was very low.
Really? Comparing it to the wavecor 8.75" that they tested and the wavecor has it beat by a healthy 15-20db on the second and third harmonics in the 50-100hz range. The frequency response rolling off towards 20hz reduces excursion and makes the harmonics go down - the morel more so because it starts rolling off earlier.

The kms for the morel doesn't actually look as bad as I expected though the wavecor is just as linear over an excursion that is about 40% larger, even being a smaller driver.
 
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TMM

Member
2007-09-01 8:37 am
Australia
Fair enough, but it still isn't 'bad' by any stretch. It's still quite low HD.
Seems pretty bad for a 10" driver to me. A 10" driver doesn't undergo much excursion to reach [email protected], it should be clean. At that level i'd expect the 3rd harmonic from 80-300Hz to be 50dB below the fundamental for a budget 10" woofer and more than 60dB for a premium woofer. Yet the 3rd order harmonic is only about 35-45dB below the fundamental through the entire usable frequency range of the driver. The price of the Morel is totally ridiculous ($479), so to deliver performance which is on par with a $50 woofer is inexcusable. I will eat my hat if something like a Dayton Audio DA270-8 performs worse.

Even a 5.5" woofer they tested which needs about 4 times the excursion to reach the same SPL still equals or betters the Morel 10":
Test Bench - Dayton Audio ES140Ti-8 5.5? Midwoofer

The results from audioXpress don't shed light on what is happening at the higher orders either. If Zaph's results from a smaller MW166 having a similar motor and spider arrangement are anything to go buy, it won't be pretty:
Zaph|Audio
 
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gbullimore

Member
2007-06-22 11:22 am
the Peerless STW is not actually a dual gap design,
it's a single gap with single VC winding,
however it is capable of 90+mm excursion Peak-to-Peak.

calculated Xmax is pretty much incomparable between brands, it seems everybody measures it differently,

the results vary wildly for a given design.
Peerless drivers use the most pessimistic (honest) value, and also give the gap geometry to let the user interpret true usability,
other manufacturers tend to use larger numbers which may or may not have any truth to them

the only real way to get an idea of excursion capability is to look at VC winding width and gap height,
anything else is at best an estimate/assumption.

the real advantage to this driver, is that it will allow a much much smaller cabinet for a given tuning.
or.
allow a much lower tuning, with a somewhat smaller cabinet,

it also suffers very little power compression.




That is calculated Xmax, and if you look closely, it's a dual-gap setup and really is likely closer to 40mm in usable operation. There is a note below the spec sheet that states this.

As to the HD and such on the smaller spider usage, VoiceCoil tested one of the Morel TiCW large woofers, and the HD was very low.

Later,
Wolf
 

gbullimore

Member
2007-06-22 11:22 am
it has taken Tymphany quite a long time getting the driver ready for launch,
i know several distributors are very keen to get it in stock. i believe it will be in stock by the end of the year.

often narrow spiders can cause problems, but like all parts of a driver, it's the challenges which set the best manufacturers apart from the pack,
i've spent some time playing around with some beta test units and the performance is significantly better than anything i have ever tested.
 
Now that I've seen another magnet geometry pic, I agree that it's a single gap. I went back and looked at my saved photo from a year ago. What isn't clear in that photo is the gap area without a physical picture. What is apparent is that there are 2 magnet structures flanking the long gap, and that is what threw me off. Before it looked like two gaps and a spacer ring, with a single coil. I never said it had 2 coils other than being a DVC architecture. The long coil was longer than what I saw as 'both gaps' before.

Again- agreed that it's just a really long gap and longer coil, and 2 tiered magnet structures flanking the gap.

Later,
Wolf
 

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bcodemz

Member
2014-02-21 1:19 am
I'm surprised nobody has paid to use Babb's spiderless, ball bearing design to get very high linear Xmax. They were making ~4.5" [IIRC] 'FR' drivers with either 1" or 1.2" Xmax/400 W peak ages ago. Scale that up to a large subwoofer........ The only downside [at least then] was the surround couldn't handle any sort of compression loading, so no BPs or horns.

GM
 
The SVS PB16 Ultra uses this driver, or a variant of this. ]

Correct. SVS marketing says it's an 8" coil but the Peerless literature says it is actually 7.4" diameter.

The smaller top magnet in the motor is used to force more flux through the gap and top plate.

There are some things I like about this driver and some that I don't. For all of that huge coil and heavy ferrite / steel motor it manages a very lackluster qts. It is very inefficient. Great at low sub bass but mediocre at best in the 40-100Hz range where most of the music is. The design lends itself to a NdFeb magnet system but they used ferrite. It almost seems like they designed it for neo and then realized the cost and decided to make ferrite work.
 

gbullimore

Member
2007-06-22 11:22 am
the challenge is actually how to keep the Qts high,
it's easy to find a driver with 0.2 Qt, but as a subwoofer this performs badly in cabinet and requires a lot of electrical compensation . unless of course you use an overly small cabinet and push up the Fs a lot,
the driver was specifically designed to be ferrite from the start,
the combination of Qt suitable for either vented or sealed cabinet, and low Fs whilst maintaining a very low Vas is not easy to achieve,
compare the driver against others in such a small box and see what the performance looks like!
 
the challenge is actually how to keep the Qts high,
it's easy to find a driver with 0.2 Qt, but as a subwoofer this performs badly in cabinet and requires a lot of electrical compensation . unless of course you use an overly small cabinet and push up the Fs a lot,
the driver was specifically designed to be ferrite from the start,
the combination of Qt suitable for either vented or sealed cabinet, and low Fs whilst maintaining a very low Vas is not easy to achieve,
compare the driver against others in such a small box and see what the performance looks like!

I will have to respectfully disagree. :)
Keeping Qts high or raising it is easy. Think of it like MPG/KPG in a car. It's not too hard to make an 10 mpg vehicle. Extremely difficult to make a practical 300 mpg car.
Drivers with middle to high Qts and low Vas have been common in car audio for a long time.
 

gbullimore

Member
2007-06-22 11:22 am
I Josh, you are welcome to disagree,

there are other drivers out there that also have high Qt and low Vas, but many of them are not great for home use, they are either too noisy (air noise) very insensitive, or have other issues,

the STW was primarily designed for home audio, and for low distortion, high excursion use in small boxes, there is not much around to compete with it like for like.

and yes, it takes some work to get a low Vas and low Fs, whilst keeping reasonable sensitivity and low distortion, with a manageable Qt,
this driver could easily have been made with a Qt of 0.2 but it would be worse for it!


it's also important not just to rate a driver based on a few numbers on the spec sheet, but to also consider the non-numerical things,
 
I will have to respectfully disagree. :)
Keeping Qts high or raising it is easy. Think of it like MPG/KPG in a car. It's not too hard to make an 10 mpg vehicle. Extremely difficult to make a practical 300 mpg car.
Drivers with middle to high Qts and low Vas have been common in car audio for a long time.

Agreed. Just weaken the motor, done.