Scanspeak 18W4531G00 sealed?

[Mario Pankov]

Hello,

I am almost done with the cabinets for my 2-way project and yesterday i started to run some simulations using WinISD. The drivers employeed are the Revelator 18W4531G00 and the XT25TG unscreened. I run the simulations and it appears that with a Q = 0.707 the F3 is around 70Hz when sealed, the group delays at 60Hz are 4s. 2nd order rolloff, I expect the room gain to compensate with +3-4db at max. The problem is that an F3 of 70Hz means i will loose a little over an octave which I need, because I mainly listen to piano/acoustic music.
As the 2-way is a very big compromise, especially when sealed, I am aware that the ported design would be a better option for this woofer/design and using it I could regain the lost octave with a little phase change and additional group delays under 60Hz.
When playing with different options, I noticed that the SS likes a bigger box volume, anything between 35-40l, when ported and tuned 30-34Hz. I`m fine with this.

Question: Is there anybody who has tested this woofer in a sealed enclosure and would you be so kind to post some measurements and your listening impressions? What I am concerned is the bass performance under 70Hz. X-over will be 2Khz or 2.2Khz, a 2nd order Bessel to woofer and 2nd order to the tweeter with a notch at the Fs to try clear XT`s strong efforts to play as a midrange ( I have noticed that ).

[Mario Pankov]

None has ever tried it? I will be covering the front panel with leather and the add-on of a port would be very hard after the wrapping. This is why I ask. I have red comments by Zaph that this woofer may go deep even in a sealed, but he has not mentioned what results he has got ( he was describing the 8531 version, I got the 4531 which has higher Fs but looks better suitable for a sealed box, this is why I bought it ). I am not sure whether John is on this website so any input from others would be appreciated.

[SGregory]

You could put the port in the back, Unless it goes on a shelf. Or use a piece of trim to make a nice clean edge for the cutout.

Just built a system with the exact same woofer. I went ported, however. During the initial crossover design phase it was in a sealed box. 1.1ft^3. It sounded very good with acoustic music. Unfortunatley I didn't have any measurements down that low.

[Mario Pankov]

Hello SGregory,

When I ran the simulations, if placed in a 14l box WinISD gives an F3 at around 70Hz, not bad at all. If we add the room gain, It might be quite good. I decided to run a test myself, I will build a test cab, a sealed straight box and will see whether this one will play deep enough at home. If not - decision is easy. As I see this is an exotic use of this driver, as nobody but you replied for almost two weeks, I will do some measurements and will post them here.

Merry Christmas!

[Berlinsound]

Hi Mario,

see the attached picture - it is a purely passive design in about 15 liters. Unfortunately I have no measurements. My listening impressions: not a lot of bass but what you get is precise. It lacks the warm punch of some vented systems - people who visit are more impressed with my vented (Dayton based) speaker. But I'm pretty happy. Next step will be an active design (also to equalize the bass a little bit).

Regards