high sensitivity speaker that moves air....

[petercom]

Originally Posted by NealG

I would love to see a three way floor standing design, with Ribbon tweeter and floor port vent. Something that is going to fit into and drive a typical UK sized living room. Something like a cross between the old Heybrook Sextet and the Elac 207.2 would be heaven!

Needs to stand about 90cm tall, have a narrow front panel with radius edges and able to work with its front panel 2ft from the rear wall, overall 6Ohm impeadance, none reactive curve and 87-90db. If I could find something like this now I would buy it on the spot! Pretty please!

Without getting too heavily into the maths at this stage, what you want Neil is exactly the item that is so difficult to design. A narrow front baffle immediately gives a sensitivity problem (if you want to look at why look up baffle diffraction on the web - if you can wait I'll cover it in a DIY article later in the year).

If you can accept a wider, perhaps tapered, baffle that merges with a rear wall then you're on.

Originally Posted by petercom

Without getting too heavily into the maths at this stage, what you want Neil is exactly the item that is so difficult to design. A narrow front baffle immediately gives a sensitivity problem (if you want to look at why look up baffle diffraction on the web - if you can wait I'll cover it in a DIY article later in the year). If you can accept a wider, perhaps tapered, baffle that merges with a rear wall then you're on.

I recently bought an old copy of Vance Dickason's LDC and the 'baffle step' issue was a bit of an eye opener. The sensitivity losses as the increasing wavelength (i.e. descending frequency) moves from half-space (2-Pi) into free-space (4-Pi) around the baffle are quite considerable. To get a flat response with 92dB/w/m sub 80Hz bass would require a woofer with a sensitivity of 98dB/w/m (or two of 95dB/w/m?) or a very wide baffle!

Tapered baffles appeal to me, as they seem to offer a big bass bin at the bottom and a narrow baffle for the mid/treble to improve imaging, judicious use of the golden ratio would help to make things look pretty. It would be good to read your thoughts on this area Peter. (I'll wait for the article!)

As an aside Peter, would you be averse to answering questions about some of your previous work (Heybrook/Mission) in the 'WD Projects' area? Both NealG and I like the Sextets and I, for one, would like to understand more about them...

[NealG]

That's interesting. I'll have to seek out a copy Matt, thanks.

Peter if we compromise the efficiency and go for 87db (I'm not constrained by SE power ) then would it be feasible? I'm looking at a pair of Spendor S6e's and they are 87/88db with a front baffle measuring 19cm, the Sextets where 86/87db AFAIK or can remember with a baffle of 27cm. So is it a question of how narrow is narrow?

I started using the Spendors over the Heybrooks because of the midband but I lost out with the treble. The Toingen tweeter sounds so good to my ears even though it's very directional, I sorely miss it.

I bought a pair of WAD KLS 6's off Ebay that had been built with the Toingen and the mid / treble is excellent but the Bass is defying all my attempts to make it sound right, plus, I have been told in no uncertain terms, that they are not domestically acceptable!

Hence I'm looking for a three way similar in size to the Spendors with a good ribbon tweeter.

[petercom]

Originally Posted by Lord.

The sensitivity losses as the increasing wavelength (i.e. descending frequency) moves from half-space (2-Pi) into free-space (4-Pi) around the baffle are quite considerable. To get a flat response with 92dB/w/m sub 80Hz bass would require a woofer with a sensitivity of 98dB/w/m (or two of 95dB/w/m?) or a very wide baffle!

As an aside Peter, would you be averse to answering questions about some of your previous work (Heybrook/Mission) in the 'WD Projects' area? Both NealG and I like the Sextets and I, for one, would like to understand more about them...

Glad that you can see the problem of narrow baffles. Unfortunately it IS a domestic requirement these days.

I'll gladly answer questions about previous designs, but I suggest you start a thread in DIY Projects/Loudspeakers where this may be of interest to other DIYers. I want to keep the WD section relevant to new designs only.

[Richard Higgins]

Hi Peter
I currently use Impulse H2s with 3 watt of se power. Although they are large speakers they can be placed close to the rear wall so are are OK in a medium sized room. They are about 96db efficient. I'm very pleased with them, they certainly show up changes in amplification, and go loud enough with 3 watts.
I would be interested in building a modern version as a kit. The speakers were from SEAS and Focal, but the originals and their replacements no longer appear in production.

Best regards Richard Higgins

[dave dove]

i currently use
living voice auditoriums
94db/w/m
6 ohm
205mm front baffle width

just not good enough any more

dave dove

[soulminer]

I tried a pair of Avatars in my system the other day Dave, and to be perfectly honest, I am glad that I had not paid £3k for them. They were nice, and did most things quite well, but nothing spectacularly, and were certainly no better than my £2k JM Labs Electras that are a mere 91dB with a 20cm baffle. I thought they sounded a little "boxy", but they did add a little extra detail and texture to things, probably due to the slightly higher sensitivity and paper cones. I think I can do a lot better than those and my 'speakers though, with a DIY pair, and I am in the process of trying a few different types/design of 'speakers in my system, and am still of the feeling that Peter is right, and that a wider front baffle may be the way to go, a la AN/E et al. I personally couldn't care less what they look like, or how wide they are (nor could my other half and she even said that Hedlunds would be fine if need be, not that I would consider them though). It's what they sound like that counts for me, although I realise that most folk need to make a 'speaker fit in or even disappear in their living rooms and that's probably why small standmounts, satellite/sub and narrow baffle floor standers are in vogue and acceptable. I would rather make them a piece of furniture in themselves and make a feature of them if you can't hide them, with lovely veneers and laquered/oiled finishes. JMO though.

[dave dove]

well exactly

i was just trying to illustrate the point
that WAF and high sensitivity
are not mutually exclusive
i prefer larger drivers
in wider baffles
and i hope my partner does too..

dave dove

[Martin213]

Or.........
Narrow,deep cabinets,where the bass driver is at 90 degrees to the others,transmission line loaded,active!(and could be large,hehe) To cut in at a frequency where s/s could be undetected,so loads of 'juice' to drive it.
That means your few watts only have to drive the mids and highs,what they are best at.
So,i have no idea about mid drivers,but definately a ribbon tweeter,and a super-tweeter?

Just a thought

Regards

Martin

[petercom]

Yup, you can do that, especially with an active LF, but high sensitivity midrange drivers are not that common and still suffer from the baffle diffraction problem if it is too narrow.