Sealed enclosure power handling characteristics

rs159

Someone please enlighten me? This dosn't look right at all? 13 watts at 50hz? Waaaaa. Is the computer just plain wrong?

BTW, my computer isn't on 256 colors, I saved it like that to quicken load times for the poor folks still using 56k.

Edit - loaded new atatchment, sorry for the huge one I had earlier

RuSsMaN

Huh? Is this your passive Morel Sub project?

Cheers,
Rooster

rs159

Russ, I dunno, I've just been playing around trying to get familiar with everything you can do in WinISD and this is something that really disturbs me. Another thing that disturbs me is the box size - 100 liters, and that's with a 1db hump in the response.

I wouldn't attempt this until I got some simpler projects under my belt, but I've seriously been thinking of using two eights or 1 ten per speaker and making myself some dandy little 3 ways. I know, three ways - eww, but the way I see it I could build myself some speakers with excelent impact and power handling -and- good sound. Seems like the only large speakers under the $600 or so it would take to build them have descriptions like:

"You can't get dem phat beats out dem little bookshelf speakaz, that's why Wu-Tang Audio built these - the hypa bass pros, for da phat bass u need. 500000 watts power handling, eight 15s for dem phat beats, tv speaker midranges so you can hear the words."

I'll confess that sometimes I do want my phat beats, but even when I want my mad bass I can't seem to forget about mids and highs and imaging and all that good stuff. I'd like to stay away from subs as much as I can until you get below around 30hz or so, just using the sub to fill in the very deepest gaps that might be left with an F3 of around 30hz. I don't know if it's just me or the rooms I've heard or what, but whenever a sub is cossed over higher than 60hz I can always pick out where it is. Just mis dos centavos

rs159

BTW, Morel claims that you can use even the tens as a mid/woofer in a two way? That doesn't even seem remotely possible, but I guess the manufacturers can say whatever they want.

rs159

Although, the charts don't show breakup until above 3000hz which perplexes me?

RuSsMaN

Well, what's the top-end of the freq response on the Morel 10"?

As far as localization, anything over 60Hz - localized, period. If you run a sub crossed at 80, and place it between the mains speakers, and the main speakers go down to at least 80, a 'mask' occurs, making it less obvious.

That is why I'm not a fan of 'small' settings in HT, if it can't do large, it's a compromise, imo.

What's the F3 on the Morel? I'd like to see Doc in this thread.

Cheers,
Rooster

rs159

With computer modeling I could get around 28 with the ten and around 32 with the 8. But judging from the graph above we all know what computer modeling could be. You also have to remember room gain that could put the F3 well into the twenties.

I'm thinking something of a DIY sonotube tuned -very- low to fill in below 25 or so.

rs159

Unless you were talking about F3 on the top end

rs159

Originally posted by RuSsMaN
Well, what's the top-end of the freq response on the Morel 10"? ...
Cheers,
Rooster

Looks good, but even a completely flat response can still sound like doggy doody.

RuSsMaN

Looks like a great woof for a big two-way.

What does Morel recommend for enclosure size and design? (venting)

Cheers,
Rooster

Dr. Spec

Hi Russ:

I have my speaks high passed at 80 Hz with a 12 dB/octave filter rate and this past Friday I powered off my sub and ran a reverse sweep on each surround channel with the Avia calibration DVD.

I was frankly astounded at how loud and how deep the surround channels are still "allowed" to play whan set to Small and high passed at 80. While the AVR was clearly (and correctly) ramping down the volume as the frequency dropped, I still had significant output from the mains, center, and 1000 surrounds well into the 40 Hz region and believe it or not - I still registered 63 dB at 25 Hz from the 800's before they signed off completely!

Not that I ever had any doubts - but for anyone that does, running on Small at 80 really does still give all the surround speaks a really good bass workout and IMO is ideal for HT and if you have a good sub and it is between the mains, it is nearly impossible to localize - the "masking" effect you refer to is clearly intentional and works extremely well.

I honestly know of no speaker in "our" collective price range that can do "Large" justice for HT, and even if it could, what about the center and surrounds? They - almost by design - need to be high passed in order not to lose the deepest bass in those channels.

I will say that there is not one sub level setting that works well for HT and music and typically the sub level is lower for music and it blends all the much better and is even harder to localize. I will concede to a 60 Hz filter point for a strictly and rigorous music application where the sub is not located between the mains.

You might want to ask HBomb of his impression of 2 channel with his dual subs - he uses an 80 Hz filter point and he has challenged 2 channel purists to locate the subs and they cannot. In addition, all of them to a person have walked away slack jawed at the depth and breadth of his soundstage.

It is entirely possible that localization of a subwoofer could very well be from harmonic distortion, as the second harmonic of 80 Hz is 160 and easily localized. I'm not saying your sub in particular suffers from audible THD at 80 Hz, only that it could be a cause of localization in some instances.

As for the rest of this thread, I'm not sure what I can contribute or make of it. WinISD is as good as any other shareware out there, but there is no substitute for actually building and exhaustively testing literally dozens of protoypes before settling on a final design. This is something I have not done, and I prefer to take advantage of someone else's sweat equity and growing pains for my main sub. Just look at what happened to Burdette's first attempt at a sono-sub - it literally shook itself apart and he is currently redesigning almost every major aspect of its build and construction, as well as eliminating the amp shelf since it buzzed badly. This is no reflection on him per se - his experiences are quite common in the DIY sub community for first timers.

If I was looking for quality bass and deep extension on the cheap, a passive SVS 20-39CS or 16-46CS would be tops on my list for under 5 bills - you just can't buy a proven better bass value anywhere and you avoid the pitfalls of first time DIY.

Regards,

Doc

rs159

Originally posted by RuSsMaN
...What does Morel recommend for enclosure size and design? (venting)

Cheers,
Rooster

The spec sheet for the 8s says in the "propaganda" section that they reccomend a sealed enclosure between 20 and 40 liters. Nothing is givin for the tens.

Dr. Spec

Here is the FR of my sub - the FR with one port plugged is what you can expect from the 16-46 enclosure.

RS - if you want help designing the volume or venting requirements for that driver, just give me the T/S parameters for it and what you want it to do, and I'll see if I can churn out some recommendations.

Doc

rs159

Holy ****, if you can get 11 hz from the 20-39 I can't imagine what the 16 could hit.

You want T/S?
http://www.partsexpress.com/pdf/297-045.pdf

http://www.partsexpress.com/pdf/297-040.pdf
I wasn't going to use the poly eight, but apparantly the paper one is being discontinued. If I use the eight I will probably use two per enclosure, BTW.

Dr. Spec

Is this for just a sub or are the woofs part of a full range unit - I can't seem to determine it from the thread.

Also, what are your goals for FR, extension, and SPL capability?

Doc

rs159

Doc, it will be part of a full range speaker. They will each be driven by a 200watt monoblock. I want to get to around 30hz anechonically (sp). I want to get above at least 110db (not that I would ever probably need it, but just to know I can).

I'm confused since you said frequency response and extension, so I'll assume you're wondering if I want it flat or if a minor dip or peak in response to achieve proper tuning would be ok? I want it as flat as it can get.

The box can be as big as it has to be, within reason. I don't have to fit it in a kid's bedroom, but something the size of a refridgerator (sp) would look stupid IMO.

rs159

BTW, I prefer sealed. I know it doesn't correspond with me wanting high SPL, but I'd rather have the sound of a sealed box than the boom factor of a vented or bandpass design. Also, I wonder if the driver would do good in a vented box or if it would overexert and go up in smoke.

Dr. Spec

OK - I see where you are heading. I'll look at the T/S specs and let you know the most suitable alignment for this driver and whether or not it can meet your needs.

And yes, FR and extension are two different animals in this parlance. The various alignments can cause peaks or dips in the FR in order to achieve any given extension.

Doc

Dr. Spec

Both drivers are well suited to a sealed alignment, since the Qt is 0.65 (10") and 0.55 (8").

If you want to hit an honest 30 Hz, I would select the 10" since it has an Fs of 25 Hz, and the 8" has an Fs of 30 Hz. Both should hit fairly low, but the 10" will do it better.

The Xmax is a very paltry 4.25 mm one way for each driver, and I doubt highly a pair of 10" will hit 110 dB down in the 30-35 Hz range. You can tell by looking at the depth of the basket that this is a very low excursion driver.

Sealed enclosures are not known for being powerhouses to begin with, and they need a long Xmax and a very strong VC/motor assembly to hit hard down to 30 Hz because the sealed enclosure loads the driver and fights it as it approaches Fs and/or the tuning point. Power compression (i.e., VC/motor heat-up and associated SPL loss) becomes a real problem with sealed subs at high volumes.

If you are really looking for 110 dB at 30 Hz, you might consider a more powerful driver like the Adire Shiva which has a much higher XMax and has been successfully employed in sealed alignments.

If you are dead set on the Morel, then I would advise twin 10" per box if you want a shot at those SPLs at 30 Hz, and even then it might be a stretch. Those woofers will quite simply bottom out very quickly at lower frequencies and high volumes.

Doc

burdette

A few things...

First, yes you can use a 10" woofer in a 2-way design... Advent pretty much made their name on large-woofer 2-ways.

As for cabinet design ... you can't design a sealed enclosure until you select a Q... I assume Doc will start at 0.7?

As for my sonosub... not quite the harsh story you lay out, Doc. In the end, all I had to do was remove the amp shelf and the base I'd designed. The fundamental part of the base - 3/4" plywood - simply wasn't/isn't enough to be stable at LOUD volumes. Right now, I have the unit sitting on 4" legs, woofer firing at the floor. No buzzing.. no problems at all. When I get a round tuit, I'll make a base out of a couple of layers of MDF.. that should do it. Both changes were necessary as a result of my *aesthetic* design issues.. not functionality of the sub.

I agree that there is no real substitute for building/testing.. but few DIYers have the resources for that sort of process.

Dr. Spec

Originally posted by rs159 I'd rather have the sound of a sealed box than the boom factor of a vented or bandpass design.

Wilson, Dynaudio, B&W, Aerial, HSU, SVS, REL - ALL vented. No one accuses them of being boomy. A vented alignment is harder to perfect, certainly, but done properly, it can sound as good as a sealed enclosure.

Many people think sealed is more musical because they seem to "start and stop on a dime", and in theory they do have a slight edge over a vented design in terms of transient response and group delay.

But of far more subjective importance is the fact that truly deep bass quite simply takes longer to decay in a room - it's the nature of the beast. And some poeple mistakenly perceive this as being "slow" because a sealed design rarely reaches below 30 Hz with authority and appears to be much "quicker" in comparison.

I will also admit that my sealed large Advents have great bass and are flat to 31 Hz and are terrific for most music. I would be perfectly happy with a sealed design for music, but not for HT, where SPL AND extension AND good sound are all required at the same time. For this, vented or PRs rule the roost.

Doc

Dr. Spec

Burdette - sorry about making it look harsh. Overall you did a bang-up job on the sub and I said so publicly. And we both worked long hours on the design phase and I naturally had a vested interest in a positive outcome. But design/build failures like yours are common, and even if they are related to aesthetic issues, they are still failures nonetheless. Can you imagine buying a commerical sub and having it fail in the manner that yours did? That would not be confidence inspiring and that's all I was trying to say about relying on other people's experiences instead of potentially punishing yourself by redesign/rebuild cycles until the bugs are worked out. I have all the confidence you will end up with a strong and good looking sub and I didn't mean to make you look bad - I'm sorry.

For a sealed sub for music, I would use a total Q of 0.5-0.7, depending on the extension requirements. No bigger than .7 IMO.

Doc

burdette

Oh, not a big problem, Doc. No doubt my level of whininess and worrying painted a darker picture than reality. I simply didn't want it left hanging out there that my DIY project in some way failed to perform in the end - don't want to cause someone else to balk at taking on a project. Frankly, I'd rather have problems due to underestimating the driver than to end up disappointed at the results due to some weakness. If I'd taken the brute force, purely functional approach to the cabinet, I'd have saved myself initial construction work/time AND saved time on problem solving. But... it was fun nonetheless. The only thing that is actually disappointing is that the base I made is just so cool... it really is.. it just won't serve the purpose. Damn materials engineers once again failing to deliver on a good design....

rs159

Originally posted by Dr. Spec
If you are dead set on the Morel, then I would advise twin 10" per box if you want a shot at those SPLs at 30 Hz, and even then it might be a stretch. Those woofers will quite simply bottom out very quickly at lower frequencies and high volumes.

Doc

I'm not really dead set on anything. This whole thread was just about an issue I had with WinISD, but now that I got something started...

I'm not even dead set on a sealed box, I thought the Morel would be more suited to a sealed box. I could build something ported or PR no problem.

rs159

Doc, the Shiva looks like a real contender. I would love to have true full rangers that dont require a sub at all (BTW, as many allready know I don't watch many movies, but a lot of my music can get demanding in terms of SPL and extension, so no **** speakers that that can't hold their own without a sub qualify as "full range" to me). Problem is, the Shiva has ragged high frequency performance so I would probably end up using something along the lines of two 6.5 inchers for midranges. Not a problem per se, it might actually do good to get the xover out of the midrange, but just something to consider I guess. Another advantage might be the same 6.5 inchers could be used in the center and surrounds to get better voice matching. The more I think about it, the more it might be better. I know I seem fickle, please bear with me, as I often get new ideas or inspirations as I'm writing my posts.

rs159

I've also been considering using a big driver like the Morel in a 2 way for a secondary system.

Damn, I have to try harder to keep my ideas straight. "One at a time" repeat" One at a time" repeat "One at a time"...

Ok, I'm better now

burdette

Do I understand you that you're considering using the Shiva as a woofer in a 3-way system? If so.. huh. I've read just about everything I could find on the Shiva and don't think I've ever seen it used as a 'woofer'... not to imply *anything* about its suitability, just that I've not seen it done.

Why not design the main speaker to reach to maybe 50-60Hz.. which a good 6.5" driver should do easily, and build either one or two subwoofers? I believe that you could build a good 2-way main, roll it off naturally, add the sub, and have a better result (and increased flexibility) than trying to design/build a 3-way that goes as low as a true sub.

Dr. Spec

Regardless, the Shiva can easily handle filter points of 80-100 Hz in a sub application.

I agree with Burdette either way - you could use mid range drivers down to those frequncies, either in the same cabinet or as separates and a dedicated sub.

Hell, some Polk mains use 6" drivers, some of which are tuned to the 35 Hz range (RT800i, RTi70).

Doc

rs159

Originally posted by burdette
Do I understand you that you're considering using the Shiva as a woofer in a 3-way system? If so.. huh. I've read just about everything I could find on the Shiva and don't think I've ever seen it used as a 'woofer'... not to imply *anything* about its suitability, just that I've not seen it done.

Why not design the main speaker to reach to maybe 50-60Hz.. which a good 6.5" driver should do easily, and build either one or two subwoofers? I believe that you could build a good 2-way main, roll it off naturally, add the sub, and have a better result (and increased flexibility) than trying to design/build a 3-way that goes as low as a true sub.

I guess it would be more like a passive LSi25, with ~6.5 inch midass/ midranges, and subs to fill in the rest.

Or I could build two subs around 3.5 feet tall and put some RTi38s on top of some Vibrapods like I was going to originally. I'm leaning towards that option considering the fact that a full ranger would be harder to construct and get right.