Thoughts on the Stryke HE-15 cube sub

[ThomasW]

I created this thread on HT-Guide to allow discussion of the performance of the HE-15 in the so called 'Stryke cube'. There has been much internet buzz regarding this design. And attempts to have a rational discussion regarding it's performance have not always been successful. So a word of warning, KEEP THE CONVERSATION CIVIL. If not, I certainly will use the 'delete' function available to a moderator, should people be unable/unwilling to control their emotions.

The 2 people SethSpeaks,in his AV Science post references, are JonMarsh and myself. I assisted Seth with the construction of his cube, and I'm the one who 'rebuilt' it after John J suggested it was 'lossy'. JonMarsh did the CLIO measurements of both incarnations of Seth's cube.

Also as stated by Seth, JonMarsh is a published member of the Audio Engineering Society(AES). So he is 'reasonably' qualified to test and comment regarding the performance of the cube. He and I are in agreement as to the performance characteristics of the cube.

The CLIO testing was done in my family room. It contains the 4 Shiva IB. The IB was used for comparison with the cube until the Aerial Stryke, AS-15 ported sub was completed.

The Aerial Stryke AS-15 ported sub design discussed HERE is a result of my lack of satisfaction with the low end transient response performance of the cube. This is a design that is more optimized for music, not just prodigious amounts of HT sound effects.

Jon will post a technical evaluation of the cube ASAP. This will include discussion of the PR's and how they 'work' with the driver.

One last thing, neither Jon nor I have any vested interest in the success or failure of this design. We like most everyone else are 'customers/consumers' of the the product.




theAudioWorx
Klone-Audio

[KennyG]

I look forward to this...

[RickS]

Thomas,

I was planning on building from the Stryke website the 15.4 version sub. By what I've read you feel that this thing will not be that good for tight musical bass? How does it sound in the 22" cube you listened to? I can read the the test data that was presented and I may have made a mistake in the purchase of these drivers.....what do you think?

Rick




The Home Theater
DVD Collection

[sfdoddsy]

I'm also curious about the differences between youe measurements and the Nousaine ones quoted at the Stryke web site.

Any theories as the disparity.

I also have a 15.2 on order, mainly because I wanted a smallish sub that could really plumb the depths with good output for music and movies.

I already have a pair of Entec subs, so I was treally looking for something to go well below 40Hz.

What do you reckon.

Steve




Steve's DIY Dipoles

[ThomasW]

Ok I'll post my impressions. I'm going to leave the technical stuff for JonMarsh to explain.

For me the lack of good low bass transient response was the main issue with Seth's cube. Now it's of course unrealistic to expect true deep bass from a small enclosure tuned to approx 18Hz. But I did expect good transient response, and it wasn't there, especially in the frequency region where the PR's were operating.

Now regarding the Nousaine data, as far as I can tell TN makes no claims as to the 'quality' of the bass from the cube . He simply compares the amount of output at 10% distortion. What I read from what TN writes, he doesn't feel there is a significant qualitative difference in subs. As a result he measures the max output at 10% distortion and the sub with the most output is basically the winner.

Also the FR plots don't really tell the whole story. Jon measured both Seth's cube and my ported design. The plots look quite similar. But there is a world of difference between the quality of the bass particularly below about 28Hz.

Now there is probably going to be someone stating the remade cube has air leaks, and that's what causes the sonic differences. Well both Jon and I tested the cube, and it has no leaks.

As far as the big bang from a small box, the cube is probably the best there is for that. It plays astoundingly loud, and one is enough to shake my 2500sq ft brick house. But there are performance sacrifices that must be made in order to get high output from such a small enclosure.....

The ported AS-15 plays just as loud, and a single one also shakes the house. But to my ears it simply sounds better than the cube. So the difference must be a fuction of the PR's vs the large port, combined with a larger enclosure.

Please understand anyone getting a HE-15 is buying an amazing driver at a significantly discounted price. And if it weren't for John J, no one would have access to this driver for a reasonable price. My only quibbles are with the PR based enclosure, not with the HE-15




theAudioWorx
Klone-Audio

[Ken Lopata]

John, your sub looks awesome. I've finished my dual 15.6 HE15 sub. Got the K2 and BFD hooked up. I've got one p.r. that if I put my ear right up against it I hear a little phh phh from. I know this is a tiny air leak. Since I need to take this p.r. off I was wondering if I should stuff my box with more polyfill. I've just got eggcrate glued to the top and bottom and a little polyfill in all corners. What would stuffing the two halves do. I believe it makes the drivers think the box is bigger. Do you think this would help or hinder. Would a so called bigger box give it a lower tuning point - is this good or bad for these drivers. Would a so called larger box give it a lower Q or one closer to .50 which I believe is the magical number to have a musical sub.

If this thing wasn't so heavy, I'd haul it over to your house to be measured. I do love this sub. Most of my listening is to movies or DVD concerts. I thought my Paradigm Servo 15 rocked, this thing is awesome. Thanks for all you help. I'd love to stop by some day.

Ken

[ThomasW]

Hi Ken

Thanks, the AS-15 is mine, Jon has yet to build his...

I wouldn't bother adding any additional poly. We tried that with Seth's cube and it made things worse.

I have a custom furniture dolly I used when building the AS-15. I could, when convenient, bring my sub to your place for a comparison.

If you want to hear the AS-15 compared to either of the IB's you're certainly welcome to drop by for a listen.




theAudioWorx
Klone-Audio

[RickS]

Thomas,

Thanks for an honest opinion on the 22" cube. I'm wondering what I'm going to do with these drivers now. Even though I haven't got them yet. My priority is not max volume bass, but I like good tight clean bass since music is still 50% of my listening. I'm using two SVS 20-39's right now that are not that bad for both music and movies(for the money) even though on some very low LFE DVD's the drivers bottom out. The investment $1236.00 for just the drivers I was hoping get good bass but, I have a feeling that may not happen. I have the space for something much bigger than the 22" cube or the 15.4 cabinet so I'd like to do the best possible with the HE15's. I will buy a BFD and do have the amp power already. So any idea's on this would be welcome.

Rick




The Home Theater
DVD Collection

[ThomasW]

Hi Rick

You're welcome, though my opinion is certainly going to cost quite a few popularity points....

I'd certainly suggest keeping/using the HE-15's and make ported boxes. You won't have any problems with bottoming. As I said the HE-15's are amazing drivers. The bass quality will be very, very, good, just not super deep. Next to the IB's I haven't heard a sub better than the AS-15. And compared to the IB's, the AS-15 is much easier to move around.

In time Jon will post an AutoCAD drawing of the AS-15. The box itself can be made larger and tuned even lower if you don't mind dealing with the additional weight. The 6" flared port is the smallest port that will work effectively with the HE-15. Just keep the general design ideas in mind if you decide to scale up the size of the box.




theAudioWorx
Klone-Audio

[RickS]

Thomas,

You're welcome, though my opinion is certainly going to cost quite a few popularity points....

The points may go both ways!

That will be great when Jon has an AutoCAD drawing done since I'll now be ending up taking this to a cabinet shop that can cut the braces for me. The 4 18" PR's will be another story. How much power are you driving the AS-15 with to get your numbers?

Thanks again for your help!

Rick




The Home Theater
DVD Collection

[ThomasW]

I was busy with other projects (building a new test baffle for a planar/hybrid array), when Jon was making the CLIO measurements, so he's the one to answer your question. When being tested both Seth's cube and my AS-15 were connected to the same amp, an Aragon 8008ST. It puts out around 500 watts/channel when hooked up to the 3.5 ohm VCs of a single HE-15. From what I could hear in the background, it didn't appear that the amp was ever being overdriven.

I did do quite a bit of listening to each design once the CLIO testing was completed. Again the 8008ST was powering each box. At no time did the amp ever appear to runout of gas when ask to drive either enclosure to house shaking SPL's. The cube with it's smaller size is slightly less efficient than the AS-15.

People should believe when told that the mininum power to drive the HE-15 is 500 watts per channel, especially when the driver response has been flattened with EQ.




theAudioWorx
Klone-Audio

[JonMarsh]

The HE-15 *is* rather power hungry, particularly at the frequency extremes (i.e., above 80 Hz and below 40 Hz. It's rated efficiency can be rather misleading, since it's combination of characteristics result in a big hump (8-10 dB) which has to be EQ'd out of the midbass (50-75 range). When you take away that hump, the actual power you need (as well as gain in the rest of the frequency region to match up with your mains) becomes quite obvious. We had Marchand's with the "mains" turned way down (about -10) and the bass gain max'ed (about +3). Refer to the EQ curve on the KloneAudio site for details about frequency contouring.

I have to say also, that in listening tests, for a subwoofer there are two things I really listen for; one is transient response, as ThomasW mentions; the other is pitch definition. The latter seems to correlate well with how rigid the enclosure walls are, and how free from spurious vibration the cabinet is. This is part of the reason that a speaker like an Avalon Elcipse can sound so amazingly clear and lifelike for just an 8" two way. The cabinet isn't absorbing and re-radiating energy from the driver. I suspect this is part of the reason I've never taken a shine to PR systems, particularly those with large numbers of PRs- at frequencies above the box tuning, they're acting as enclosure walls, and generally not very good ones, at that.

The HE-15 is very demanding of the cabinet performance. Since we can still detect some slight vibration in the cabinet walls, I suppose I could make the case that is isn't quite stiff or massive enough. But can I make a case to build it even stronger? Could we move it around if we did? All good questions.

As placed in the listening room we evaluated these "portable" subs in, the AS-15 was very smooth at the listening position; (I should have measured it at that position also, for reference, but things were very hectic that week) in fact, I'd say it was the flattest low bass I've heard in ThomasW's family room though not quite the deepest. By flat and extended, I mean down to 18 Hz. With a variety of demanding program, bass guitar, double bass, cello, and a variety of fast percussive drums were reproduced quite well. Thomas's Ravi Shankar CD got a reall work out, as well as a special "Bass/Dynamics" demo CD I've assembled with cuts from a variety of artists, including Jacque Loussier, Oregon, Ravi Shankar, Andreas Vollenweider, Ambrosia, Emily Remmler, Laurie Anderson, and Stanley Clarke.
I must also agree that there is a certain weight to nominally higher frequency percussive material (mid bass) that is more solid and focussed with clean extension to 18 Hz, which the AS-15 did in a very satisfying manner.

So I'm fairly excited about finishing the second Aerial Stryke, but now I'm also curious about developing an AS-12, i.e. doing a more direct SW-12 clone design with a Blueprint driver, given it's low Q and high excursion capability. Have to run it through the sims, and see how it looks.

Now, if I can just figure out a way to get my employer to put me on paid sabbatical, I could really get some audio productivity under way....




Earth First!
_______________________________
We'll screw up the other planets later....

[Brandon B]

In your 2nd post here, you said you expected good transient response from the PR design and were surprised it wasn't there. So are there any design changes to the PR design that would help?

I am building the 15.6 dual driver version but was radically changing the shape of the cabinet (6 foot tall eq triangular tower with HE15-PR-PR-HE15 down the front side and blank-PR-PR-blank down each of the other 2 faces). The uncorrected volume of my enclosure is somewhat more than the stryke design, so I was wondering if there was anything I could do to improve the transient reponse without tossing out the PR's. I've already purchased them, an since John J has already got most of the parts, I don't think it would be fair to him to ask to return them.

However, if there is no other solution, my enclosure will allow for one or 2 very long ports (5 feet or so).

Thoughts?

Thanks.

BB

[ThomasW]

Brandon

Understand Jon and I are posting our opinions, just as others have posted their's. People are obviously divided regarding aspects of how the PR's effect the performance. Many people are in love with the PR based designs. Jon and I simply don't share that opinion.

So I'm sorry to say I think the PR's are the problem, and I know of no solution other than not using them.

If you have the time build a single cube with the PR's and give it a listen. If you like what you hear build the PR based box. If not go with the ported design.

You'd want to use a port length close to that in the AS-15 which is 28.5" flare end to flare end. Any significant increase in length and you'll run into issues with port resonances.




theAudioWorx
Klone-Audio

[Brandon B]

OK. I know you guys are working hard to keep civility in this discussion and so no make bold or aggressive statements. But to me "poor transient response" is a quantifiable non-subjective analysis. Since I'm new to speaker building, but have a pretty strong technical background, I was wondering if you could explain why we would get poor(er) transient response out of the PRs vs. your ported design? I thought the two types of systems responded in a very similar fashion except for the rolloff at the very bottom and the notch at PR resonance. Since John J was also tuning to about 18 Hz, what's causing the different behavior? Is it even partially the larger volume of your cabinet?

Also, do you guys have a number for the internal volume of your SW-15?

Thanks again.

BB

[ThomasW]

Brandon

Yea in 'theory' ports and PR's are pretty much the same. Jon and I have been designing and building speakers together since 1969. And during that time we've built other PR based enclosures. None however have sounded as good as a properly executed ported design.

Jon has some ideas as to why that is. He's the engineer so I'll let him answer the technical stuff. Currently he's up to his *ss in alligators at work so he won't be able to post a proper answer for a day or so.....

As for the volume of the box, the gross internal volume is just under 6.8 cu ft. Deduct for the the port, driver, internal stiffening braces, the gasket felt, and the volume drops down to approx 5.5 cu ft. We used a 160L LspCAD Pro model to calculate the port length, then crossed our fingers

FIY, the internal depth of the box was calculated so as to give 6" of clearance between the end of the port and the rear wall of the enclosure.

>>>Edit

Spoke briefly with Jon, he want's to do a compare/contrast with the CLIO measurements and the LspCAD models of the cube and the AS-15. He needs to email the LspCAD models to me and I'll upload them to the website. Then Jon will post the why's/wherefore's/etc, of the differences in the designs.

So be patient and we'll give you all the objective data we have.....




theAudioWorx
Klone-Audio

[Jack Gilvey]

I thought the two types of systems responded in a very similar fashion except for the rolloff at the very bottom ...

It was my understanding that the severity of that very rolloff was a prime factor in determining transient response. If so, a fourth order vented system should have better transient response than a fifth order like a PR. And both would be inferior to a second-order sealed system.
This is very general, of course.

[Lex]

I am just guessing here. But my Sonus faber Grand Pianos are a PR design. not quite sure why Sf chose to use PR, but they did. When driven hard at full range, I actually get a fluttering sound from the PR. not good. Every time I hear this, I instantly lunge to the volume control.

Fact is, except for music, I don't run them full range, I cross them at 80. When I do this, it's no problem.

Could the base problem be PR "flutter" at significant SPLs? If so, I can see how a ported design might be better. Even though from the get go, everyone said, go PR, go PR. I never truly understood that, as damn beefy as this driver looked. It sure looked like a ported design could work, and work well.

Lex