Leeloo construction about to begin

[David Gatti]

These are my bookshelf surround speakers that will be based on the Scanspeak 15w8530k-01 and (probably) Morel Supreme 110.

I've posted some design notes here http://www.gattiweb.com/leeloo_design.html

I haven't finalised things completely yet. Any input is appreciated before I start the woodwork.
Cheers
David

[sreten]

Hi,

I'd say to work well you'd need some form of heavy
decoupling between the speaker and the stand.

/sreten.

[David Gatti]

That's a good point. I'm hoping the 1" baffle will be solid enough to prevent any vibrations, plus there will be some sort of rubber or felt isolation between speaker & stand.

[ShinOBIWAN]

They look promising David.

I'd have never have though of integrating storage into the stands. Ingenius!

Didn't you consider dipole or bipole driver arrangement?

I plan to look into it after I've (eventually) finished the Perceives. I was thinking about a direct radiating design on the front baffle, in much the same way you've got now. But also putting a couple of wide range drivers such WR125's and cutting the treble at around 3-4Khz and roll them off at around 300hz. The aim is just to provide a little more space to the sound without over doing the whole thing as some surrounds seem to do. These would be bipoles too.

[5th element]

The leeloo *wonders where that name came from*

[ShinOBIWAN]

Originally posted by 5th element
The leeloo *wonders where that name came from*

Maybe he should spray them orange on top with a lot of bare MDF showing?

[David Gatti]

Originally posted by 5th element
The leeloo *wonders where that name came from*

Hehe, yeah lets hope they sound a lot clearer than she did

Shin, yes I did consider bi/dipoles - from what Ive read, the jury's still out on which is best, but it seems that di/bipoles are better for movies but direct radiators better for multi-channel audio where localisation & imaging are more important. My preference would always be for music.
Also, dipoles don't quite fit in with my goals (will be close to corners), they'd be larger & more expensive, and designing their frequency response seems a bit too empirical for my liking.
I'm still a little concerned about low frequency power handling of the 15w8530, and wonder if a bigger driver like the 18w8531 would be a better choice. Any thoughts on this?
I'd better do some more reading on the low frequency requirements of surround speakers.

[ShinOBIWAN]

Originally posted by David Gatti


Hehe, yeah lets hope they sound a lot clearer than she did

Shin, yes I did consider bi/dipoles - from what Ive read, the jury's still out on which is best, but it seems that di/bipoles are better for movies but direct radiators better for multi-channel audio where localisation & imaging are more important. My preference would always be for music.
Also, dipoles don't quite fit in with my goals of a linear phase system, they don't suit my positioning requirements (may be in a corner), they'd be larger & more expensive, and designing their frequency response seems a bit too empirical for my liking.
I'm still a little concerned about low frequency power handling of the 15w8530, and wonder if a bigger driver like the 18w8531 would be a better choice. Any thoughts on this?
I'd better do some more reading on the low frequency requirements of surround speakers.

In a perfect world, and especially for music, the surrounds would be another pair of Delta's. Frequency/time charateristics matched being the benefits.

But it seems that small speakers are the only sensible option if you live in houses like most of us on here do. So they state that 80hz is a good cutoff point and then pass the rest of the non directional sound to the subs. This actually has advantages over running full rangers all around because the bass-room interaction is lessened. It can also be argued that if correctly setup multiple sources of bass smooth room modes, however, typical placement often means that room modes are actually excited more and you generally end up with more cancellation and bigger humps. Room treatments are pretty much futile below 80hz so the best bet is to use DRC. My advice would be to just make them sats and pass the bass onto the Samsons.

Regarding the larger bass driver - if you do only take them down to ~80hz then the smaller revelator is fine unless you think your going to need higher SPL's and or lower distortion?

[David Gatti]

I'm just concerned about how a 4th order rolloff to the surrounds would combine with the 2nd order rolloff of the mains (might try modelling it in LspCAD), hence I'd prefer to keep surrounds set to large. Their closer proximity to the listening position (about 2 metres)and less programme content should mean that power requirements is not an issue.
BTW, I just been loking at the products of my favourite manufacturers, Vandersteen, Duntech and Thiel - none of them use bi/dipole surrounds.

[ShinOBIWAN]

Originally posted by David Gatti
I'm just concerned about how a 4th order rolloff to the surrounds would combine with the 2nd order rolloff of the mains (might try modelling it in LspCAD), hence I'd prefer to keep surrounds set to large. Their closer proximity to the listening position (about 2 metres)and less programme content should mean that power requirements is not an issue.
BTW, I just been loking at the products of my favourite manufacturers, Vandersteen, Duntech and Thiel - none of them use bi/dipole surrounds.

I wouldn't worry to much about the roll-off rates and phase related issues by doing so. From experience with measuring the Perceives I can tell you that by the time the room takes over, the phase of a modelled response vs. actual response inroom will be completely different and especially at such low frequencies. You can't design for such contingencies, at least not with current software, but you can give it a go and see which measures/sounds better once the speakers are working. It should be a quick task to add in the LFE filters for the surround on the amp. Be sure to let the surrounds roll off naturally as you don't want a 2nd order lowpass + 4th order lowpass when doing the cut at 80hz.

About the speakers you mentioned at the end of your post; the average buyer of those brands usually has a large listening room and doesn't use them in the near field (2m). They are the ideal solution but I can't help but think that bipoles may be worth a try also.

Bipole's have obvious advantages when used in such close proximity to the listening position. I've been into HT for a good while now and I very nearly always prefer bipoles to direct, in fact I can't ever remember preferring direct for surround on both music and HT. You mention that your placing them close to the wall? This can actually increase the ambience of the sound since its reflected off a boudary and back in to the listening position. Its not accurate per-se but it does sound more involving and generally better to me and that's what its all about. Designing for perfection is a good start but experience tell's me that in my room, bipoles work better. It a tough call and I can completely see where your comming from but have you confirmed that your room sounds better with direct or bipole?