3-way with Seas U18RNX - DXT tweeter - Mid?

[g.org]

Hey folks.

My first post her will be a question about a 3way system.

I am wondering if anyone have made a 3way floorstanding with 2x Seas U18RNX/P - Seas DXT tweeter plus midrange?

I have theese speaker elements. Just missing midranges.
I have built the Seas Idunn and really like the sound they produce, so my thought was to make a 3way system with these drivers and just add one midrange.
My problem is that i am a neewbie and would feel a lot safer to build something thats already tested
So then im asking here)

The U18 can be swapped with other drivers, but the tweeter is a keeper.

So if anyone can help me i would be grateful

Regards

Georg

[g.org]

Spoken with Idland at Seas in Norway and he has done some simulations for me.

Will be using 2x U18RNX - 1 MCA12 - 1 27TBCD in each speaker.

apprx. 42 liters for bass - 2.5liters for mid.

Very cold in Norway these days so building will not start yet

[WE4242A]

The sensitivity of MCA12 is only 86.5dB.Two U18 will go 91dB around
Seems this will work:http://www.scan-speak.dk/datasheet/pdf/15m-4624g00.pdf

[Curt C]

Adding a midrange to a well designed 2 way will have the potential to reduce Doppler and compression distortion, as the midrange is exempted from the bass duties and large excursion requirements. All else being equal, the 3 way will sound just like your 2 way but perhaps a bit cleaner and more resolved at higher SPL’s.

I’d suggest you spin it the other way: Since you like the sound of the present 2 way, use the U18 as the mid, and reinforce the bass with a larger driver or pair of drivers. The additional advantages will be the potential for greater bass extension, greater SPL capabilities, and better system sensitivity. As the woofers can compensate for the baffle step, the resultant system could be up to 6 db more efficient than the present Idunn design.

There are advantages of using a larger diameter driver for a midrange, most having to do with increased mid pass band capabilities, and potentially lower distortion due to lessened cone excursion. A purpose built mid driver may perform slightly better, but since you have the U18’s already, this design option might be worth some consideration.

There are lots of good woofer candidates out there. As an example, I just finished a crossover for a 3 way floorstander which used a pair of Usher 8955A woofers per side. They paired up nicely with a Revelator mid and OW1 tweeter. I suspect the U18 / DXT used as a mid and tweeter would offer similar performance.

C

[kmibb]

Adding a midrange to a well designed 2 way will have the potential to reduce Doppler and compression distortion, as the midrange is exempted from the bass duties and large excursion requirements. All else being equal, the 3 way will sound just like your 2 way but perhaps a bit cleaner and more resolved at higher SPL’s.

I’d suggest you spin it the other way: Since you like the sound of the present 2 way, use the U18 as the mid, and reinforce the bass with a larger driver or pair of drivers. The additional advantages will be the potential for greater bass extension, greater SPL capabilities, and better system sensitivity. As the woofers can compensate for the baffle step, the resultant system could be up to 6 db more efficient than the present Idunn design.

There are advantages of using a larger diameter driver for a midrange, most having to do with increased mid pass band capabilities, and potentially lower distortion due to lessened cone excursion. A purpose built mid driver may perform slightly better, but since you have the U18’s already, this design option might be worth some consideration.

There are lots of good woofer candidates out there. As an example, I just finished a crossover for a 3 way floorstander which used a pair of Usher 8955A woofers per side. They paired up nicely with a Revelator mid and OW1 tweeter. I suspect the U18 / DXT used as a mid and tweeter would offer similar performance.

C

Is this design going to be published? It sounds promising. What are your thoughts on it vs the Statements?

[g.org]

There is differense in sensitivity, but this was taken in consideration in the xover. The guys at Seas say according to measures and simulation with the filter they put together sensitivity will be approx. 89db for finished speaker at 1 meter.

I am going to put my faith in them and build this

Will find out if this goes bad or good when tested.
If it goes bad i have two options. Either try to adjust xover or use other drivers+xover.

Will be fun building them anyway

[Curt C]

Is this design going to be published? It sounds promising. What are your thoughts on it vs the Statements?

I don't have a pair of Statements on hand to compare, but they are both quite close in performance. The differences would be the sound of the ribbon and metal mids vs soft dome and slit paper. The WmtmW configuration of the Statement seemed to provide a bit more tactile bass. (The Usher build was a physically less imposing TMWW 3.5 way.) I'd say it would come down to personal preferences as to which would sound better.

I don't have the right to make this particular design available for popular consumption.

C