I'll go out on a limb and state the U18RNX-P is Seas best sounding 7" midbass for anything critical in terms of accuracy and overall resolution in a dedicated 2 way monitor application.
The woven poly cone Seas midbass are some of the most suitable LF drivers for 2 way designs. They are in reality more accurate and resolving in the midrange than most paper cones. This goes against typical traditional thinking that poly cone drivers usually sound blurred or veiled in upper mids - this just isn't always true,
What many people don't understand is the so called poly cone sound doesn't mostly come from the cone material itself including other additives thrown in to modify internal dampening characteristic. Its also affected by the geometrical profile, shape, thickness and weight, plus the design of surround its combined with. The surround interaction with the cone is a huge determining factor in the way a driver will overall perform in the midrange. The dampening behavior of the surround together with the cone is responsible for most of the performance in the upper rolloff range.
When chosing a good midbass for a 2 way (specifically larger ones), you always want to look for gradual upper mid rolloff with multiple smaller resonances rather than sharper single peaks. Most designers will favor drivers with sharper, single upper mid breakup peaks than multiple, diffused peaks. This isn't a good choice, as higher Le hides other issues while creating some even worse problems as a result.
Seas designed the U18/U22 woven poly cones to have a very smooth and gradual upper rolloff with more benign smaller amplitude, spread out peaks. At the same time, they managed to keep Mms and Rms low.
Whoever the designer is at Seas responsible for these woven poly cones is a very talented guy. These aren't your typical boat anchor, veiled and bloated sounding solid poly cones found in cheaper drivers. They also didn't bump up Le to fudge the upper curve, which is often done to clean up rolloff, but this can substantially raise IMD/THD.
I frequently say that I prefer paper cone drivers to other types, but the U22 and U16 oddly sound alot like a mellow paper cone driver rather than having that typical poly cone sound. I believe it has alot to do with the way the cone was woven along with carefully thought out geometry of cone and surround as a unit together. Very few drivers in this price range sound as clean and open, while having great low end capability and overall resolution.
Both the U18 and U22 are suitable for use in critical monitoring applications with 2way designs. They can be crossed higher than most cone drivers of their size while staying very composed, given you aren't so hung up on ruler flat off axis FR.
When comparing 8" drivers with different cone designs, the Audax HM210C0 is also on the top of my list, but it surprisingly sounds similar to the Seas U22, which plays lower in a smaller enclosure. The Audax has a little bit of an edge on the Seas in terms of low end capability.
The Seas U18 is however overall the best 7" midbass I've heard in its price point and beats other more expensive drivers in the midrange, plus it has good sensitivity. We used to think the Vifa P17WJ00-08 was the most suitable 6 - 7" for budget 2 way monitors, but the Seas is a much better driver all around. It should hopefully be available for a long time to come.
The woven poly cone Seas midbass are some of the most suitable LF drivers for 2 way designs. They are in reality more accurate and resolving in the midrange than most paper cones. This goes against typical traditional thinking that poly cone drivers usually sound blurred or veiled in upper mids - this just isn't always true,
What many people don't understand is the so called poly cone sound doesn't mostly come from the cone material itself including other additives thrown in to modify internal dampening characteristic. Its also affected by the geometrical profile, shape, thickness and weight, plus the design of surround its combined with. The surround interaction with the cone is a huge determining factor in the way a driver will overall perform in the midrange. The dampening behavior of the surround together with the cone is responsible for most of the performance in the upper rolloff range.
When chosing a good midbass for a 2 way (specifically larger ones), you always want to look for gradual upper mid rolloff with multiple smaller resonances rather than sharper single peaks. Most designers will favor drivers with sharper, single upper mid breakup peaks than multiple, diffused peaks. This isn't a good choice, as higher Le hides other issues while creating some even worse problems as a result.
Seas designed the U18/U22 woven poly cones to have a very smooth and gradual upper rolloff with more benign smaller amplitude, spread out peaks. At the same time, they managed to keep Mms and Rms low.
Whoever the designer is at Seas responsible for these woven poly cones is a very talented guy. These aren't your typical boat anchor, veiled and bloated sounding solid poly cones found in cheaper drivers. They also didn't bump up Le to fudge the upper curve, which is often done to clean up rolloff, but this can substantially raise IMD/THD.
I frequently say that I prefer paper cone drivers to other types, but the U22 and U16 oddly sound alot like a mellow paper cone driver rather than having that typical poly cone sound. I believe it has alot to do with the way the cone was woven along with carefully thought out geometry of cone and surround as a unit together. Very few drivers in this price range sound as clean and open, while having great low end capability and overall resolution.
Both the U18 and U22 are suitable for use in critical monitoring applications with 2way designs. They can be crossed higher than most cone drivers of their size while staying very composed, given you aren't so hung up on ruler flat off axis FR.
When comparing 8" drivers with different cone designs, the Audax HM210C0 is also on the top of my list, but it surprisingly sounds similar to the Seas U22, which plays lower in a smaller enclosure. The Audax has a little bit of an edge on the Seas in terms of low end capability.
The Seas U18 is however overall the best 7" midbass I've heard in its price point and beats other more expensive drivers in the midrange, plus it has good sensitivity. We used to think the Vifa P17WJ00-08 was the most suitable 6 - 7" for budget 2 way monitors, but the Seas is a much better driver all around. It should hopefully be available for a long time to come.
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@PKAudio The 700 hz bump in HD is a resonance caused by a radial breakup mode at the cone/surround junction. It can be reduced by applying a viscoelastic dampening compound at the surround cone junction.
I've been doing some experiments with 3D printed TPU rings designed to dampen this area. Its a pain to get the material and adhesive consistent, so a repeatable design could make this easier to control.
Alternatively, a soft neoprene foam ring coated with soft urethane compound could be easier to implement. The problem is usually lack of adhesion to the surround and cone area.
Polypropylene doesn't like to stick to most adhesives, but being a woven fiber, it may substantially help the situation. There's also alot of vibration in that area, so that further complicates it.
I've been doing some experiments with 3D printed TPU rings designed to dampen this area. Its a pain to get the material and adhesive consistent, so a repeatable design could make this easier to control.
Alternatively, a soft neoprene foam ring coated with soft urethane compound could be easier to implement. The problem is usually lack of adhesion to the surround and cone area.
Polypropylene doesn't like to stick to most adhesives, but being a woven fiber, it may substantially help the situation. There's also alot of vibration in that area, so that further complicates it.
profiguy: thanks for sharing your extensive knowledge. Not only technical stuff, but subjective evaluation as well, and that is what I am interested the most.
I have U16, U18 and U22 and will experiment with those, hopefully ending up with a several nice sounding designs.
Regarding cone edge treatment, I bought Intertechnik Vinylflex and plan to experiment with it. I did several layers on a paper, and it is flexible, still somewhat soft, it is durable, it is not sticky to the dust, and it does not break.
I have U16, U18 and U22 and will experiment with those, hopefully ending up with a several nice sounding designs.
Regarding cone edge treatment, I bought Intertechnik Vinylflex and plan to experiment with it. I did several layers on a paper, and it is flexible, still somewhat soft, it is durable, it is not sticky to the dust, and it does not break.
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@PKAudio. It can be tricky trying to find out whether a specific compound actuslly has the desired dampening properties rather than storing energy and releasing it back into the suspension, making the issue worse than it was before.
I'd be interested in seeing your results. There are only a handful of dampening substances which actually work well on speakers.
I'd be interested in seeing your results. There are only a handful of dampening substances which actually work well on speakers.
SEAS does the cone edge treatment on the W22NY003
http://www.troelsgravesen.dk/W22NY003.htm
Seems to be industrial secrets...
This is the reason I look pro-driver they do not exhibit such flaw.
http://www.troelsgravesen.dk/W22NY003.htm
Seems to be industrial secrets...
This is the reason I look pro-driver they do not exhibit such flaw.
I am using the Seas U22REX 8" up to 1kHz and crossing to 1.4" compression driver/horn, and the quality of the entire midrange is surprisingly clear and detailed, the CURV cone not sounding like it's lagging behind the compression driver. When you tap on the CURV cone, the sound is much lighter and less dull sounding than the average non-woven poly cone.
So I took a measurements of U22 and SB26ADC today. Just an experimentas I had Sb26 already at home. Cabinets was properly filled with damping material and port shortened to 11cm to achieve desired tuning ~40Hz. Quick crossover modelling in Vituix shows quite good results, actually not bad for 8"+1" 2way without WG.
Good thing is that bass crossover requires 2mH inductor, the same value I ordered for U18 2way project. Inductors should arrive early next week so soon I will do listening tests of this U22 experiment.
Good thing is that bass crossover requires 2mH inductor, the same value I ordered for U18 2way project. Inductors should arrive early next week so soon I will do listening tests of this U22 experiment.
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That bump around 550 Hz looks very familiar to what Troels saw with the U16RCY/P. Here's how he dealt with it: http://www.troelsgravesen.dk/SEAS-CURV.htm
Yes, that came to my mind as well. I will first listen to it without RLC though. These gated 5ms measurements they can make things look better or worse leading one to equalize what does not have to be equalized. It is the reason I look at the ungatted measurements, and will do also outdoor measurements to obtain more accurate data.
Oddly enough, I had a similar FR peak with most 8" woofers in such a compact enclosure. I came to the conclusion it was caused by the cabinet height interaction with the port. There was also a 3rd order HD peak at the same frequency. I tamed the peak with a small pillow made from sheeps wool wrapped loosly by a single layer of grille cloth, placed horizontally in the middle of cabinet and stapled by the corners to the front and back walls. This lowers the high pressure zone of the standing wave and reduces the H3 peak.
Yes ! Never observe that because i don't use reflex port, but PR or aperiodic box.
This weekend I connected U22 prototype and had two listening sessions. Both U22 and SB26ADC sound great.
Overall sound of this 2way is fine, I do not detect any directivity issues.
U22 is the biggest surprise, it has vivid sound, very neutral, firm and detailed, snap is there, and bottom end extension is sufficient, better then majority of 6", and it liked higher listening levels.
SB26ADC sounds very good, though I miss the top level details of Be tweeter, but is is just to put the things in the context. For 50eur tweeter I do not have any complaints.
Now my plans for U22 + ?? tweeter + WG are even more feasible.
Overall sound of this 2way is fine, I do not detect any directivity issues.
U22 is the biggest surprise, it has vivid sound, very neutral, firm and detailed, snap is there, and bottom end extension is sufficient, better then majority of 6", and it liked higher listening levels.
SB26ADC sounds very good, though I miss the top level details of Be tweeter, but is is just to put the things in the context. For 50eur tweeter I do not have any complaints.
Now my plans for U22 + ?? tweeter + WG are even more feasible.
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Tw29bn. I have them already at home, and wg are ready, with the holes for 3 dome protection elements. This combo is meant for another project, but it will take some time before cabinets arrive, so I can try it with u22 first.Seas T 35 w/ Jantsen waveguide I presume
T35 is on my "really would like to try" list.
