Enclosure suggestion for super 8 rs/dd please...

[sagamotto]

Hello everyone,

I want to build a pair of speakers for music listening with the wharfadale super 8 RS/DD. They are in very good condition. Can someone suggest what enclosure best suited for this driver? I try searching on the net but got very few information on it. I mostly listened to jazz and classical.
What is interesting about this driver is that it classified as a wide range which most likely I would need a matching tweeters in order to make this work which I would need your help as well. It's rated at 10-15 ohms again another problem with amplification, any suggestions???
According to other source that I have found on the net is that above around 5khz things started to going crazy. Dispite the fact of high QTS value of 0.63, most people would prefer to be used as open baffle with a larger woofer for the low end. I did a preliminary test on a 25"x25" board to see how it sound and it didn't produce very much low end, probably a larger baffle would improve thing. Vocal and instruments sound pretty good but the whizzer cone sounded very distracted at a distance of about 2m on axis, this definitely suggest some sort of EQing or filtering network. But too big of a panel for open baffle would take too much space in my small room (12ft x 10ft). I would prefer the speaker's to be place in the corner distance at about 10ft apart on a stand.
Any comments or enclosure ideas would be very much appreciated.
Thks in advance.

 

[picowallspeaker]

whizzerectomy ?!?

 

[sagamotto]

Hi Picowallspeakers
Yeah... The whizzer cone remedy method, did try that on some other drivers. It work!!!

 

[picowallspeaker]

well, maybe the driver is useless, despite of what the net says. I don' care about the numbers but cone diameter and excursion: and a 8 '' has got to make a lot of bass.
It could be a 60 dB bass...but who cares ?
After whizzerectomy, an inverted dustcap would make the driver look very stylish !

Ps. just saw the photo on the net ; the magnet is huge !! And it has an inverted surround...nice.

 

[sagamotto]

Just pick up an idea from other post about the Rondo clone out of foam core sheet...
Would this work for this drivers? Instead of floor stand, how bout smaller on stand mount with the top open...

 

[sagamotto]

Well I still think this driver could sound pretty sweet if it is implemented right. I could knock off a 1 cubic feet enclosure with slot on the back and see how the bass response is...

 

[picowallspeaker]

You don't want the back wave to produce interference with the frontal emission.
It's better to 'leave it behind' or...let it live, but far away !
About the foam core...
well...
it's in contrast with the basic principle of speaker boxes ...

 

[GM]

Greets!

It looks like Troels has already worked out a good way to get the most out these drivers and I’m not into stand mounting, instead preferring tower [aka MLTL] designs to get the drivers up to ~ear height, so using his specs: Wharfedale Super 8

H = 56”
S0, SL = 144.25”
Zdriver = 19.55”
Zport = 44.8”
port = 5” diameter or 19.64”^2 cutout x 0.75” [baffle thickness]

All dimensions are inside [i.d.] and approximate and sim only has just enough damping to keep them from sounding hollow, so as always it’s up to the individual to experiment with damping and maybe port tuning to get the most satisfying response in room.

Class A or at least very low nfb amps is desirable, but I don’t keep up with what’s available these days, so no clue what a modern day version of a period correct one that was used to ‘voice’ this driver is.

GM

 

[sagamotto]

Hi GM
Thanks for taken the time on this, but the box suggested dimensions is just too big for my room. (H:56", S0 & SL:144.25") ? Could you suggest something smaller ?

Another thing I would like to mention also is the driver's half roll surround, the cloth like material is so thin that I could see right through it which probably could be used in a sealed type of cabinet and used the driver's air transparent surround as an apperiodic mean. Wouldn't that be interesting? Anyone with any thought on this sort of contraption?

 

[waam68]

You could try a clone of Gilbert Briggs "column 8" design as here:

Identifying these Wharfedales - UK Vintage Radio Repair and Restoration Discussion Forum

or perhaps go old school & have a look in his Cabinet Handbook?

 

[sagamotto]

Thks Waam68
Certainly will look into that... Interesting cabinet design! Almost the same concept as the infamous A-25. Speaking of which, I wonder if that cabinet idea would work with this driver??? Any suggestions to dimensions like the A-25 bookshelf type of speakers?

 

[GM]

Greets!

You’re welcome!

Really?! I mean I’ve had larger, taller speakers in the corners of a ~ 8 ft^2 square room without them getting in the way, so with a ~1 ft^2 square speaker ‘footprint’, or better yet, triangular ‘built-in’ corner ‘hutches’ to do double duty as a heavy planter ‘shelf’ to add some mass loading, I’m curious why these are too big.

Regardless, it can be made smaller, it just means it will have less bass, tuning flexibility and may not be able to get the driver’s HF up high enough to line up with ~ the seated ear height unless a sloped baffle is used, so what are the max HxWxD dims you can tolerate?

Hmm, not familiar with this driver or what cab alignment the factory used/recommended, but Toels doesn’t mention it being lossy nor do his measurements imply it, so I’m inclined to assume it’s not lossy, especially since other drivers I’m familiar with that have the same type of surround aren’t lossy either.

If yours are though, then a large sealed alignment may be the best overall choice if you’re not willing to [re]seal the surrounds.

GM

 

[sreten]

the cloth like material is so thin that I could see right through it

Hi,

And it is too thin and too porous, basically doesn't work,
and stops the driver producing any bass at all, awful.

rgds, sreten.

 

[sagamotto]

Thanks again GM...
I don't mean "...too big" as in size wise, it is just abit tall.
I'm thinking along a maximum of 4' in height including spike feet, as shallow as possible hence placing them near wall. Would these preferences changes it characteristics of producing better low end dispite of shorter internal back wave reverberation? Could place lots of damping behind the driver though...

 

[GM]

You’re welcome!

I’ve built very wide, shallow cabs only as deep as the driver and they do ‘suffer’ from the same acoustic damping issues as high aspect ratio ducts, so generally need less internal damping, but some of the tall cab’s vent damping goes away as the trade-off.

Still, with normally no need for baffle step loss correction [BSC] from being right up against a wall or even diagonally across a corner, it’s usually a worthwhile trade-off.

Anyway, here’s the original except shorter [less net Vb] with a bottom firing vent since it will be spaced up on spikes:

H = 45”
S0, SL = 144.25”
Zdriver = 9”
port = 5” diameter or 19.64”^2 cutout x 0.75” [baffle thickness]

The second sim is same as above except with the original’s net Vb:

H = 45”
S0, SL = 179.5”
Zdriver = 9”
port = 5” diameter or 19.64”^2 cutout x 0.75” [baffle thickness]

Note that due to room loading, a 3” diameter vent to tune it lower may be required to keep it from ‘booming’.

All that said, if sreten is correct, then sealed [no vent] combined with additional stuffing in the driver area may work best overall if you don’t seal up the surrounds.

GM

 

[sagamotto]

I visited the hardware store (Home Depot) today looking for some thin plysheet to curb the speakers but realized after it isn't that easy. They are i think 1/8" thick, I tried pinch bend with my hand and thumb they are stiff as hell...
Anyway, looking across I saw some paper tube which normally use for poring cement and I though why wouldn't this work. So I ask the gentleman to help me take it down so I can take a closer look and to my surprise it is pretty stiff and it give a very mild resonates when I knock on it. This could be good or bad depending on which design I choose.
I noticed non of the tube are perfectly round in shape, perhaps internal bracing could straighten this issue. Could wrap some simulated leather to increased the thickness for the finishing.
Has anyone used these paper tube for speakers enclosure? Would like to hear some comments or experience on this...

 

[sagamotto]

Thks GM
I would go for what you have suggested, but was wondering how high would you recommend the spike feet? Since placing the port on the bottom.
If I used the 3" diameter, how long would it needs to be?
Like most coax driver, HF beaming could be very harsh, would it be a good idea to slightly tilt the front baffle a bit? (how much degree tilted?) Speakers will be place about 2.5m apart and seating at 3.5m, 18inches from the wall... If that's any help.

 

[DrBoar]

I have used the paper tubes for both 6.5" and 10" drivers
http://www.diyaudio.com/forums/full-range/208169-very-simple-quarter-wave-pipe-miditrike.html
With a straight line between the opening and the driver some midrange will get through

 

[GM]

I’ve used concrete formers a bunch since the ‘60s and there’s been builds published on various forums since at least ’96, though they’ve mostly been TLs, vented subs.

As a general rule, using double thickness inner/outer end plates will make them round enough for most folks, though of course round ‘window’ braces can be added along its length. That, or pay more for Sonotube.

The best bracing I’ve tried is to use threaded rod to tie the end plates together and put them under a very minor tension, though this is normally only necessary for subs with large, high Xmax drivers.

I normally recommended/used wallpaper or fabric, though I’ve seen leather and even alum. coverings also. The tubes I used were only waxed on the inside, but the cheap ones folks usually use have some sort of slick coating on the outside too that they claim is hard to deal with, so tend to make fabric ‘socks’ to cover them.

GM

 

[Squeak]

I'd say that with the HF peakyness and very rising response of the driver the right cab for this would be something like the one shown on the first page. IE a driver firing straight up, probably put all the way into a corner to get loading and to gently and efficiently reflect HF off the walls into the room.
For that cardboard tubes would be very well suited. Maybe one inside another to increase the length (organ pipes were once made this way, and out of strong cardboard too).

I've had great success with putting felt on speakers. It has wonderful acoustic properties, is easy to work with, looks good and comes in many colours.

For the leaky surround, a thin layer of damar would be the obvious answer. Easily obtainable from any art supply store.