Woofers/distortion measurements?- 10" SEAS L26ROY3 & L26RO4Y2. And 12" Peerless XXLS (alu) 835017

tktran

Has anyone have or have seen measurements of these woofers?

New black 2 layer VC version of the L26ROY
http://www.seas.no/index.php?option=com_content&view=article&id=609:extreme-04-l26roy-3&catid=97&Itemid=603

An oldie but I never saw measurements:
https://www.parts-express.com/Peerless-835017-12-Aluminum-Cone-XXLS-Subwoofer-264-1114?quantity=1

I have an oldie but a goodie- paper cone 12" XXLS: 830845; great for sealed boxes of 2cu or less.
https://products.peerless-audio.com/transducer/207

Still looking for that elusive "best woofer that has OD of 240mm or less"

dcibel

https://audioxpress.com/article/test-bench-the-l26roy-10-subwoofer-from-seas

dcibel

You might also consider Wavecor:
https://audioxpress.com/article/voice-coil-test-bench-wavecor-s-new-sw259wa01-10-25-high-xmax-subwoofer

tktran

Thanks for pointing those out.

Just looking to compare with the upcoming Purifi 10”.

I feel like Vd is still king; so a good 12” should still outperform a good 10”. But I don’t have any data.

Quad RS270 in isobaric might still take up less cabinet space and funds, annd outperform the (very) expensive 10” Scan or Purifi

charlielaub

My advice: save up your money for the 10" Purifi... Of course this only has so much Sd*Xmax, but what you get out of it will be very, very clean. Moving up to a 12" driver does not necessarily get you cleaner output, only more total displacement. That is not always "better". Case in point:

I have a set of eight 45L internal volume closed box subwoofers in my living room. I used 12" drivers that were not expensive. They have about 9mm Xmax each I think, but in total there is a lot of swept volume. Unfortunately they really don't sound good - above 50Hz they are very muddy, and I need to cross them over near 100Hz. I used an LT to try and correct the Q to something more "cleaner" and "leaner" sounding but it's all mud, mud, mud. It's inherent to the driver.

In contrast, I recently picked up a high performance 12" sub and put it in about the same volume (different enclosure). It sounds so much better than the EIGHT other drivers. Of course it won't have as much LF slam, but at least it is a pleasure to listen to.

jr@mac

@charlielaub said:
My advice: save up your money for the 10" Purifi... Of course this only has so much Sd*Xmax, but what you get out of it will be very, very clean. Moving up to a 12" driver does not necessarily get you cleaner output, only more total displacement. That is not always "better". Case in point:

I have a set of eight 45L internal volume closed box subwoofers in my living room. I used 12" drivers that were not expensive. They have about 9mm Xmax each I think, but in total there is a lot of swept volume. Unfortunately they really don't sound good - above 50Hz they are very muddy, and I need to cross them over near 100Hz. I used an LT to try and correct the Q to something more "cleaner" and "leaner" sounding but it's all mud, mud, mud. It's inherent to the driver.

In contrast, I recently picked up a high performance 12" sub and put it in about the same volume (different enclosure). It sounds so much better than the EIGHT other drivers. Of course it won't have as much LF slam, but at least it is a pleasure to listen to.

I ran in to that with the GRS 12" drivers I am using in my listening space. It was obvious I have to cross at 80Hz or lower. I wouldn't call it "muddy" above that point, but that may just be semantics. They sounded like shit by 120Hz and just sound cheap above 80Hz.

tktran

Hello Charlie,

What were the drivers in question?

@jr@mac

My suspicion is that the driver is not a low inductance design, and not suited as a woofer. Strict LP 80Hz only.

I’m looking for a driver with an OD equal or less than 240mm that is a as good a woofer as possible out to least 250Hz.

I recall a comment by Tim Felappa over at DIYA:
I shall copy and paste it here so as not to take it out of context:

“This doesn't only effect metal cones. It affects all types of cones. Paper cones have just as much breakup as metal cones, just that the breakup nodes have a low quality factor, i.e. the energy is spread over a wider range of frequencies rather than being a more pronounced narrowband spike. Untrained eyes will look at the datasheet of a driver like the SEAS CA18RNX and conclude that it has minimal or no cone breakup but they couldn't be more wrong.

If the CA18RNX had a 'resonance free cone' installed, the response would be rolling off already by 2kHz yet in the frequency response we see something that looks more or less flat out to 7-8kHz. Why is this then? Cone breakup is pushing the response up to flat from 2-8kHz. The inductance of the voicecoil is rolling off the response at the same rate the cone resonance is boosting it back up. Why is this bad then? Divide that range by 5 and you get 400Hz to 1.6kHz, then check out the 5th order harmonic in the plot I posted and what do you know, there's a broad increase of 5th order harmonics from about 400Hz to 1.6kHz. This is because any 5th order distortion that is created (by non-linearities of the magnetics, surround, spider) at those frequencies hits the breakup of the cone and therefore plays louder than it otherwise would with a truly resonance free cone.
Another indicator of cone breakup is to check out the impedance plot in the drivers datasheet and we see the impedance has doubled from the minimum of Re=~6ohm to 12ohms by about 2kHz. Therefore we'd expect the response to have fallen by 6dB at 2kHz but instead it hasn't fallen at all, therefore we can conclude the cone is breaking up by +6dB at 2kHz. If you don't understand why this is, we drive speakers with a voltage source so if the impedance has doubled the current has halved, and the pistonic movement of the cone is proportional to current through the voicecoil. Half the current is -6dB.

A revelation huh? You can look at just the frequency response and impedance plot in the datasheet and have a reasonable guess at how much higher the distortion will be at certain frequencies! This is a good trick to scoping out good drivers without having to buy and test them, and avoiding ones that aren't worth buying. If the impedance is going to the moon in the datasheet and the frequency response is not falling off a cliff in response, you can bet that the driver won't perform very well at least 2 octaves below where that happens.

Of course, what the frequency response and impedance in the datasheet can't tell you is how linear the magnetics/surround/spider are in the first place. If those parts are exceedingly linear then you don't care about cone breakup messing up the overall linearity of the driver since the harmonics won't be audible even being boosted up by breakup. Unless you are buying Satori/Scanspeak level drivers then this is seldom the case so knowing the above interpretation techniques will be a valuable skill to have in selecting drivers that deliver value for money.”

https://www.diyaudio.com/community/threads/advantages-and-disadvantages-of-having-the-woofer-mid-in-a-2-way-run-wild-with-no-woofer-leg-on-the-crossover.394425/post-7240096

Wolf

Not sure I buy that. Some drivers look horrible in measurement and still follow Tim's example above. The HiVi F6 for example has a wonderful midrange quality and does not measure as most prefer, yet it sounds great to 3.5kHz.

tktran

It may sound great up to 3 1/2 KHz. I don’t have a problem with that.

But if I am to interpret the frequency response and impedance graphs in the manner that Tim describes, I would argue that it is most accurate up to 750Hz.

(Minimum impedance 6.5ohms; 13 ohms crosses at 3Khz. 2 octaves below this is 3000/2/2=750Hz.

Furthermore there is an impedance blip just over 1KHz. So at a stretch; the ideal working range if this speaker is up to 1KHz.

I haven’t seen any measurements of this driver, but it will be interesting to see what the harmonic and/or intermodulation distortion measurements say…