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fred76 30th April 2006 11:01 PM

Supravox RTF64 design options (long)

Just want to gather opinions here WRT to suitable enclosures for the 215 RTF64.

I know S-vox is renowned for their drivers in OB. But I'm not going that path this time as I already have OB speakers using high Q vintage drivers (I just lack a good sub to fill in from 50-40Hz below for more demanding material)... Although still usable for OB, the RTF64 is not really the most ideal for it in S-vox's line up anyways. They have the slightly more pricey 215 Signatures for that.

I want to try pipes or quarter-wave designs for a new project this time.

1.) The general design suggested by S-vox for the 215 series looks nice but maybe there is room for improvement:
What do you think?

2.) Another design I'm contemplating is a pipe/blh with a Karlson vent:
(should read 1" x 4" bracing)

We built a pair of these before w/ oridnary ply and it sounds great with low Q drivers so far (tried with both FE207E and EX2's). I asked the designer (Bill Woods) who kindly shared it in the public domain for diy if a higher Qts driver like the S-vox would sound good in 'em. He told me that the only way to know is to actually try. Well, before letting go of considerable $ I'd like to know what you guys think. *He did a sim comparison Vs. JBL LE8TH using Akabak and sent me the response graph linked below. The dips are said to be artifacts of Akabak, but IME trying out high Qts drivers in backhorn or pipe designs is that they tend to sound boomy with midbass suckout. The not so encouraging part is that the designer says they LE8TH is quite bass heavy in that enclosure. Both the S-vox and JBL driver have very similar Q, although other parameters like Vas are far from each other:

*Akabak sim LE8 vs. RTF64 on K-lsot vented pipe:

3.) Another that is of interest is the Singular enclosure (interesting backchamber with Helmholtz resonator). Its said to work well with medium Qts drivers up to .6 or so. Will try this path too

Of course there is the cool BIB design, with dims graciously provided by GM. However, width and depth is too large for my room Im afraid.:(

Anything you may share would be greatly appreciated. Thanks for reading the longish post.


Scottmoose 1st May 2006 12:35 AM

I've been meaning to run a MathCad sim on those enclosures for a while. If you give me until tomorrow morning (well, it's technically morning already, but I need to sleep!) I'll run a few numbers.

A dirty great vented box like the old Tannoy enclosures might also be an interesting option, although it's not nominally that close to the TL type[s] you want to try out.

fred76 1st May 2006 11:28 AM

Hi Scott,

Would wait for any design sim you may come up with... Thanks!:)


sumacSK 1st May 2006 06:30 PM


Look here
Seems to be intresting design.

Good luck Martin

Scottmoose 1st May 2006 08:06 PM

2 Attachment(s)
OK, here's what the driver looks in the Supravox TQWT.

To be honest, it's not too bad. This is a fairly quick model; I didn't refine to the 'nth' degree, but it's as close as should make no difference. I deliberately applied no stuffing to the model -a small quantity will take out the worst of the ripple.

It wouldn't be my choice for this driver, as IMO, it's not got enough volume -one of the reasons it cuts off a bit high for my taste, but I wouldn't mind sticking a smaller unit in it -in fact, I checked it with the FE168ESigma, to good effect. Someone (Can't remember who, off-hand) on the board is in fact doing just this.

fred76 1st May 2006 08:13 PM

Hi Martin,

Thanks for posting the floor-loaded design by Fillipo. It faded in my memory that I browsed that page af few years ago. The resonators are more elaborate than the single one of the Singular.


Scottmoose 1st May 2006 08:14 PM

2 Attachment(s)
OK, here's a possiblility, if you've got the space. I came up with something similar a couple of weeks back for a friend with Coral Flat 10s, albeit rectangular, which wasn't ideal, but what he wanted. If you don't like the shape, you can make it whatever you want -just keep the CSA the same, or within a few percent of 236in^2. It's not small, but with driver's like these, you really need to have a sizable enclosure to get the best performance out of them.

I actually borrowed the layout and CSA from the original Tannoy Lancaster corner cabinet as I rather like it. It's stretched vertically to 42in tall (internal) though, and the big original rectangular vent is replaced by a single circular port, 4in diameter, 2in long, 4in up from the internal bottom. I'm lousy with CAD software (learning a couple of decent programs is on my to-do list), so I simply modified the original Lancaster drawing to reflect the changes. Sorry the internal length is so small -as I say above, it should be 42inches. 0.25lbs ft^3 of stuffing used in the top half of the enclosure.

Scottmoose 1st May 2006 08:18 PM

2 Attachment(s)
And here's the FR graph. This enclosure is on the border between being an MLTL and a BR I suppose -whatever you feel like calling it, it seems to work pretty well -roll-off is in lock-step with room gain, so it should be pretty flat to around 40Hz or so, and it'll still by belting out notes into the 20s, no problem. Smaller versions are possible of course, but if you've got the space, this'd be one of my top choices. Pretty nice efficiency too. Give me a shout if you want something smaller & I'll try to come up with something.


fred76 1st May 2006 08:55 PM

Hi Scott,

I appreciate you doing a sim on the the Supra TQWT. I suspect the early LF rolloff is deliberate to avoid over-loading when placed near corners (?).

The Tannoy design looks sweet. The only problem I think is I've only got ~8.5' (width of the room) of space where the l/r speakers would be placed - too close to each other. Maybe a version that is narrower but taller? BTW, that's a textbook FR graph!

I have a heavily modifed SET amp that puts out around just 7W (but 'stiff' psu and driver stage). I'm not sure how amp damping factor would play a role in large BR 'hybrid' deisigns.

I would be out of town for 2 days. I'll have online access when I get back to ask a few more questions. Thanksabunch!:)


GM 1st May 2006 09:44 PM

2 Attachment(s)

Looks pretty good in a hybrid Onken, but its footprint isn't all that much smaller than the BIB. High Qt = big box if it's going to play fairly low.


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