2.5 or 3way

[deki]

I am about to build speaker with scan speak drivers:21w8555-01,
18w8545 and 99000 revelator tweeter.I am in doubt which xo
layout is better,2.5 way or 3way for given drivers.
Speaker will be acoustic suspension. Deki.

[Cal Weldon]

2.5 ways are best suited to identical bass drivers. Different units will sound different at the frequency overlap

[TurboFC3S]

I was kinda wondering this too ... will either deliver (in general) benefits in certain areas? If I had to guess I'd say a 3 way would potentially be more detailed and clean in the midrange, but that the 2.5 way would have more bass volume and impact.

[sreten]

Hi,

As you state it depends on the given drivers as to which would be best.

Attached is a series 2.5way for Scanspeak drivers, see source.

/sreten.

[Cal Weldon]

I found the 2.5 way was effective when using smaller drivers like the CSS WR125's.

[croat47]

Related...I think:

I was wondering about doing a 2.5 way where the .5 was ported and the other (same driver) was sealed. What major issues are there here? I see phase (~60deg) and a peak at F3 in group delay...anything else?

Regards,
Aaron

Edit: the phase shift and group delay were specific to my model on RS125's using Zaph's measurements.

[TurboFC3S]

Originally posted by croat47
I was wondering about doing a 2.5 way where the .5 was ported and the other (same driver) was sealed. What major issues are there here? I see phase (~60deg) and a peak at F3 in group delay...anything else?

Ha, me too! I have some cabinets here begging for a pair of Dayton RS180's ... but one chamber is sealed, the other vented.

[PeteMcK]

'2.5 ways are best suited to identical bass drivers' - probably depends how low you cross them over; I'm currently using a 2.5 way with 5"Peerless mid-bass & oddball 8" bass units, crossed over at around 120Hz - I'm very happy with them.
5" & 8" units in separate cabs, both ported; the 8" units are EBS alignment (because they're both different units - cabs tuned differently to get same response).
I'm going to try blocking the ports on the 5" cabs & add an extra cap in the xover to see how they sound, but with a touch of bass boost at the amp, this system sounds really solid & clear - love it...
Cheers,
Pete McK

[Willitwork]

Separate cabs usually involves LP bandpass filter effect on the mid and even without knowing the enclosure volumes involved I would imagine that frequency overlap between drivers is relatively narrow. Wouldn't such a configuration be considered a 3-way rather than a 2.5?

[croat47]

I guess it ultimately is a 3-way with similar drivers. As I do not see any objections, I suppose the silence after the questions is actually saying "Try it!"

Regards,
Aaron