2.1 way or 3 way?

Hi guys.

I am in the process of designing a three way speaker in a similar vein to the Troels Graven Jensen 1071 or the Focal Utopia.

It started out that I wanted to build a nice two way standmount speaker based on Scanspeak Revealator drivers, then build two subs to act as stands. Then I came across the Troels Graven Jensen 1071 and I started to think a three way would be better, to reduce the intermodular distortion in the mid due to having to reproduce low frequencies.

I want to build the drivers into three separate boxes a la Focal Utopia for a couple of reasons: I like the look, I like the idea of having separate chambers and isolating each driver from some of the vibrations from the other cabinets, and also - as a diy fiddle freak - I like the idea of being able to try different drivers. A modular approach to upgrading.

I currently have some drivers that I have collected over the years so to start me off I want to use those. I eventually want to use better quality and more expensive drivers, but for now my budget means I shall use what I have.

The tweeters are Scanapeak D2905/9000 (sticky domes)
The mids woofers are Peerless CSX-176H (800122 I think)

For Woofers I am torn between either the SLS-269 woofer or XLS 269. The reason is: cost! The SLS are quite inexpensive drivers and fit into my budget. Looking on Ebay, I can also get a pair of the XLS drivers for not much more cash, so both are good cost options for me.

Basically my question is: Should I go for the SLS woofer or the XLS? Both will be used in a sealed box of approx 50 litres.

With the XLS I also considered the possibility of running a matching passive radiator, though the increased group delay might lower the sound quality and the low end extension might be over-kill! I would like a flat in room response of 20-20k though.

I will be running the speakers actively, probably with Hifimediy T3 amps (T3 for the woofers, and T2's for the mid/tweet), using minidsp (or something similar like the Behringer DCX2496).

So: What would sound best?

SLS 10" - sealed approx 50-60 litres, crossed at about 300hz
XLS 10" - sealed appox 50-60 litres, crossed at about 200-300 hz (looking at the fr graphs, they are actually quite clean to about 500hz)
XLS 10" passive radiator either 50-60 litres or smaller to suit, crossed over at 200-300 hz
XLS 10" passive radiator either 50-60 litres or smaller to suit, crossed over at a more traditional sub level of 80-120 hz

I realise the XLS is a heavy woofer and would probably enefit from being crossed lower, but the lower it is crossed the more the mid-woofer is being asked to reproduce lower frequencies. This increases the IM distortion. If I am fully active, it gives me the chance to try different crossover points out luckily.

There is a benefit to me of using 4ohm woofers (the XLS is 4 ohm, the SLS is 8), due to the class t T3 amps making more power and less distortion into these lower impedance loads. Up to 300 watts at 4 ohm, up to 150 watts into 8 ohm.

Your input will be greatly appreciated!

Regards,

Jai Stanley
 
I've tried using XLS drivers (crossed over low) with a 2-way as well as on 3-way and preferred the use of woofers and not subwoofers for music. Drivers such as the old Vifa M22WR, M26WR and the newer SEAS CA26RFX spring to mind.

There are those who do like the use of the XLS drivers but most I have seen are used in OB.

The speaker in the pic uses the 18W8531 with a M22WR-09-08 in a 2.5 way arrangement even though it looks like a 3-way.
 

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Thanks for the replys guys.

I have been thinking about it and I see the benefit of having two 'subwoofers'. They will mean I dont need to also build a large subwoofer to cover just a tiny part of the sound spectrum. I'm lucky in that my girlfriend appreciates my music taste and love of soud quality and will put up with large speakers, that said my room isn't huge and I could do without a large sub. The price I will pay will be running my mid-woofers that little bit lower and the intermodular distortion that introduces. Something like a scanspeak revealator will allow me to go down to 100-200 hz cleanly I assume so I think I will just have to try to get over it.. :)

I have been looking at drivers...

What do people think to the new scanspeak discovery 10" subs? Model: 26W/4558T00

I could build these sealed or with the matching passive radiators. They model very nicely in a 50 litre box, both passive or sealed. With room gain taken into account I think the passive radiator designs will play flat in room to 20hz! (F10 is approx 20hz). Sketching up the boxes in autocad I think I will be able to get a nice curved side panel at around 40-50 litres for these. Should be more than enough vol.

These woofers are most definately subs, but they look well behaved up to approx 1khz. Remember, I will be using minidsp's so can EQ that peak out of them (due, I presume, to the aluminium cone first break up mode). I will be able to try different crossover slopes so think I will be able to get a good comprimise out of them.

What do you think? Do you think I will be missing a lot if I run the mids down to about 100hz? These woofers are a bit of a stretch of my budget but I thik they'd be worth it. Plus, there's that nice something orother to having all scan-speak woofers.. Sad, I konw...

Jai