file FSP-MAGICBOX

12 years 2 months ago #3567 by deadbeat
FSP-MAGICBOX was created by deadbeat
I think it's time we all sat down and had a big think. This may be a bit early (seeing as we're all hard at work with the two midtops...or should be lol) but I think I should make this thread anyway.Inspired by Rog's latest efforts, and various other things, I think there's a big gap in the diy sub section.It is of course, a wideband high efficiency sub for one way bass. By wideband, I mean very wideband, not seen in most diy subs to date.

Here's some preliminary constraints:

The sub must not be monstrous in size.
The sub must be able to get past 150hz, but the real target is 200hz. This is, of course, cleanly.
The sub must have LF extension to less than 40hz (+-3dB from the HF point). Our real target is 30-35hz [img]smileys/smiley15.gif.
The sub must do this reasonably cleanly.
The sub must be of high efficiency.
The sub must be able to reach all of this in a single cab (pairs at a stretch).
The sub must be LEV-STANDARD.

Well, I guess this would be quite a massive feat if we all did it and it worked great! That's a massive understatement.[img]smileys/smiley36.gifAny thoughts? I'll post mine after a few replies.Oh god my head hurts.

Update:

We have a few new goals, team.

Our new target for f3 is proper sub - 20hz or so
[img]smileys/smiley17.gif Edited by: Deadbeat

[url=\"http://users.ece.gatech.edu/~mleach/beraneklaw.html\"]Beranek\'s law[/url]
\'bits of ply round a driver\'

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12 years 2 months ago #3569 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX
Why magicbox?

Have you heard of the real majicbox before?

Its gotta be a ported horn i'd say, perhaps 2x drivers per cab so the horn can reach down to the port(s) eaisier (than a single one) in singles.

but the more suggestions i make the more i'll be describing the stasys X.....

If someone can teach me how to tune a chamber to act like a really long port then that'd be helpful!

Have you read the stasys X thread deadbeat? (on SP)

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12 years 2 months ago #3571 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX
"The sub must be LEV-STANDARD"

So you're saying we have to make a scoop play cleanly, I QUIT!


(or a wsx...)Edited by: Jake_Fielder

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12 years 2 months ago #3572 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX
What are peoples opinions on how many folds you could have and still get to 200Hz...
1? none? i dunno..

Because if you have a straight horn then its going to have to be a monster to play down to the port, which i assume would have to be tuned to ~38Hz ish. A straight 50Hz horn is not small! This is of course assuming that ported horn is the way to go, (which i firmly believe it is...)

I think this is a great idea, can you tell? i have already posted 3 times!

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12 years 2 months ago #3573 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
I have read the stasys thread and I know about Boyd[img]smileys/smiley36.gif bit of a gag.

But I really want to avoid a stasys x clone, we'd be no better than china. But the resonating chambers concept is interesting...

A sub that is Lev-standard (duuuuraabbllleee) has to survive 24 hours of sinusoidal basslines (aka you know what i mean) while having a carefully conditioned spray of liquid (sweat) misted at it. And Lev has to say it sounds good. 200hz cleanly in a scoop? I can do 20K in a rear loaded horn cleanly, but it only takes 5W lol.

[url=\"http://users.ece.gatech.edu/~mleach/beraneklaw.html\"]Beranek\'s law[/url]
\'bits of ply round a driver\'

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12 years 2 months ago #3574 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
I would say 90 degree folds are the way to go.

Ported horn? I was thinking maybe a double horn, perhaps.

The Stasys X does 34hz-200Hz +-3dB. But cleanly, I'm not sure, you'll have to ask toasty or someone else with a few.

I think you might be interested in this a lot. Reflectors vs curved bends finite element analysis.
http://ldsg.snippets.org/HORNS/images/roundbend/

[url=\"http://users.ece.gatech.edu/~mleach/beraneklaw.html\"]Beranek\'s law[/url]
\'bits of ply round a driver\'

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12 years 2 months ago #3575 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX

Deadbeat wrote: I have read the stasys thread and I know about Boyd[img]smileys/smiley36.gif bit of a gag.

But I really want to avoid a stasys x clone, we'd be no better than china. But the resonating chambers concept is interesting...


I know, but i think its about as good as you can get, i have always prefered single to double driver cabs anyway. (hence the prototype im hoping to finish tonight)

Deadbeat wrote: A sub that is Lev-standard (duuuuraabbllleee) has to survive 24 hours of sinusoidal basslines (aka you know what i mean) while having a carefully conditioned spray of liquid (sweat) misted at it. And Lev has to say it sounds good.

It also needs to survive having a pint poured into it![img]smileys/smiley36.gif

Deadbeat wrote: 200hz cleanly in a scoop? I can do 20K in a rear loaded horn cleanly, but it only takes 5W lol.

I know, thats why i edited my post shortly before you replyed. I realised what i was saying was easy

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12 years 2 months ago #3576 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX

Deadbeat wrote: I would say 90 degree folds are the way to go.

Ported horn? I was thinking maybe a double horn, perhaps.


You said it cant be too big!

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12 years 2 months ago #3577 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
Thanks for the detailed reply. By not monstrous, i mean we should try not to get to terra horn size. I'm thinking of something like a tasco harwell bass bin, if you know what I mean.

But let's concentrate on a port for now. How many ways can we make a long port less obtrusive? There's folding a port, then there's Rog's design. And if we had a very long port, I think it would exhibit a bit of transmission line. Hopefully jsg will chime in at this point, he's very into his chambers.

The Stasys X does represent the epitome of the range, I guess.

I spent a while on my post, didn't see your edit sorry.

On a completely different note, has anyone experimented with using an aperiodic sealed rear chamber? Would make it much smaller.

Edited by: Deadbeat

[url=\"http://users.ece.gatech.edu/~mleach/beraneklaw.html\"]Beranek\'s law[/url]
\'bits of ply round a driver\'

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12 years 2 months ago #3579 by tommysb
Replied by tommysb on topic FSP-MAGICBOX
What do you mean by aperiodic?

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