Scanspeak 3way. OB or closed\vented?

[Leliks]

Dear All!

I'm desinging a new DIY construction with Scanspeak Revelator tweeter and 5'' midrange 15M\4831.

I got a couple of options of bass section:

- Scanspeak 26W paper woofer in sealed\vented box
- 2xScanspeak 26W paper woofer in sealed\vented box (to better matching with sensitivity of midrange and tweeter)
- 2x15 or 2x18 professional drivers in open baffle.

What I'd like to end up with : natural, light, boom-less representation of sound.

Please share you opinions.

Thanks in advance.

[zimjj]

...go with a Hiquphon OW1 tweeter and an SB Acoustics 10" woofer. The Hiquphon tweeter, also Danish, is a marvelous tweeter. The SB Acoustics 10", Danish design, will get an F3 of 24 Hz in a 55l vented box.

JZ

[gainphile]

Let's see...

natural ... OB
boom-less representation of sound ... OB
light: not sure what you meant but if it's "open" then ... OB!

I'm not biased btw

[rabbitz]

What you have to consider first is what your room can handle and how it's going to react with the speaker. OB do require a lot of space (>1.2m) behind the speaker as well as a very large room to perform at their best.

If going for OB, I would suggest using the 15W or better the 18W as it will give better power handling and excursion. In an OB the 15M could run out of excursion as the driver will have no acoustic loading. The W versions have greater xmax. If you run the 26W in OB then 2 would be required plus plenty of equalisation.... but I think you mentioned sealed / vented for the bass.

Vented is going to give the best extension and is the path I take but sealed could be a good option if it suits your tastes as well as if it's able to go deep enough.

I did a similar speaker and tried S2905 + 18W OB + 22W vented and my room could not support the OB mids. Eventually it became a 810921 + 18W sealed + M22 vented which suited the room so much more. After trying various drivers that was the final selection.

Have a look at this speaker as may give you some ideas and the path you could take.
Jensen-

The SB Acoustics could be a good option for the bass as I believe they do make some good woofers even though I've only tried their smaller mid woofers.

[Leliks]

Originally Posted by rabbitz

What you have to consider first is what your room can handle and how it's going to react with the speaker. OB do require a lot of space (>1.2m) behind the speaker as well as a very large room to perform at their best.

I have enough space to accomodate the OB speakers, it's OK.

Originally Posted by rabbitz

If going for OB, I would suggest using the 15W or better the 18W as it will give better power handling and excursion. In an OB the 15M could run out of excursion as the driver will have no acoustic loading. The W versions have greater xmax. If you run the 26W in OB then 2 would be required plus plenty of equalisation.... but I think you mentioned sealed / vented for the bass.

Currently I have 2way on 18W revelator midwoofers, and I'd like to get rid of 18W in favour of fair midrange (15M) and fair bass speakers. 2way is always a compromise...

15M is intended to be used >300Hz where it's excurtion will be in range of Xmax(linear) even at loud levels, I've already simulated this. However I still doubt whether to use OB or box (large vented tuned low\sealed with variovents to get rid of of compression) for midrange...

Originally Posted by rabbitz

Vented is going to give the best extension and is the path I take but sealed could be a good option if it suits your tastes as well as if it's able to go deep enough.

Have a look at this speaker as may give you some ideas and the path you could take.
Jensen-

Yep, this is one of option that I consider. But I'm afraid sealed\vented could be boomy and boxy. I listed to a low of classical and acoustical music...

Originally Posted by rabbitz

The SB Acoustics could be a good option for the bass as I believe they do make some good woofers even though I've only tried their smaller mid woofers.

I think that usage of Scanspeak\Seas\SB Acoustics woofers is possible only in vented\closed boxes, and I believe they will not able to perform in freeair due to small area of surface. In order to try the OB I aim on PRO speaker 15 or 18 inches, such as Eminence or 18sound.

Once again - this is a question - OB with 15-18'' or sealed closed with 10''.

[thomasjefferson]

If you're up to going through a prototype stage on this project, then try to get your 18W to serve as midrange. It should perform very well. Just choose a tweeter that can cross relatively low to improve the power response.

OB bass has a reputation for needing large speakers, but if you're able to actively equalize, a pair of 10's can provide solid output in a modestly sized cabinet. That is, less imposing and easier to build than what you'd need for a 10" in a closed box. It seems like you'd be a good candidate for OB.

[rabbitz]

Don't under estimate the quality of the 18W when you remove bass duties.

Linkwitz did a lot of tests on mid drivers and came to the conclusion that smaller drivers don't cut it in OB. However an MTM arrangement in OB can overcome these issues on power handling and SPL.

[gainphile]

Originally Posted by Leliks

Yep, this is one of option that I consider. But I'm afraid sealed\vented could be boomy and boxy. I listed to a low of classical and acoustical music...

Well yes, they will be boomy and droning. That's not the fault of the speakers but that's how monopoles interact with rooms.

Given your uncertainty I would suggest a U-frame OB (for the woofer part) let's say with depth 30cm. Then you have the ability to close the rear and it becomes a sealed box. Cross at 160hz to avoid the pipe resonance.

Acoustic instrument recording should be reproduced with least coloured speakers. That means no box.