Can a subwoofer be used successfully in a 3-way design?

[Bill poster]

thinking of the excellent Peerless XXLS(seen them going cheap)... was hoping they might be good if used a high power mid/bass driver??

[Josephjcole]

Certainly, subwoofers can be used just like any other driver. Just like using any other woofer make sure to crossover well before any cone break up occurs. So I would think it depends more on the matching of the mid-bass driver and subwoofer.
Joe

[tinitus]

Peerless XXLS might be one exception that actually would work like 'ordinary' woofer
maybe because it is more woofer than a sub thing

Ground Sound

[Bill poster]

Originally Posted by tinitus

Ground Sound

That design is v helpful. I think a mid/bass with a higher power rating would be beneficial. The outgoing XXLS seems to be more suited, lighter cone, higher sensitivity.

Any idea what drive units this uses? http://www.acousticzen.com/maestro.html

[doug20]

I use AV15Xs from AE speakers in 3-way full range deisgns.

Make sure the Le value is low so that you have linearity in the higher frequencies.

[Norris Wilson]

Or,

You could use your Peerless as a sub in a design such as this with a plate amp.

FYI

Custom Walnut Planetarium Alphas

[PEB]

I have experience with this. Here are some tips.

1. The higher the cross point, the more important it is to use subwoofers in stereo pairs.
2. The higher the cross point, the more important it is for the subwoofer driver to face forward.
3. The lower the cross point, the more complicated and expensive the passive crossover circuitry for the midwoofer becomes.
4. First ascertain the behavior of the subwoofer driver with increasing frequency. The Peerless XLS cone behaves well enough, but the wide surround resonates at 600Hz. This is true for most wide surround woofers. You will want to cross the woofer no higher than an octave below the trouble frequency. In this example, 300Hz would be OK.
5. Next, consider the sensitivity difference between the subwoofer and the midrange driver. Generally, a good performing subwoofer driver is less sensitive than the typical midrange woofer. If you vertically bi-amp the speaker with two identical stereo amplifiers, you can attenuate the monitor amp sections with Harrison inline attenuators. Same for horizontal bi-amping with two different amplifiers.
6. But a sufficiently large sensitivity difference will be problematic for a fully passive 3-way crossover. You need to consider separately powering the subs with plate amps, or separate amp and active crossover.
7. Venting the subwoofer helps the sensitivity issue. Fire the vent out the back to prevent midrange leakage. Tuning the cabinet low can be challenging with vent lengths and areas, mechanical layout, etc.
8. Finally, EQ may be needed to get the subwoofer section to measure flat. This is also more challenging with a fully passive crossover.

Soon I plan to design a fully passive 3-way speaker with integral 8” subwoofer driver and 6” mid-woofer.
BTW, I have four Peerless XLS-10” woofers on sale at my sale page. Ask me why they are as good as the XXLS version.

Philip Bamberg
BESL

[Bill poster]

Thanks for this Philip; I was thinking to cross at around 300 - one idea is to use the rather expensive Morel carbon rohacell mid/bass, at least its bullet proof. I'm hunting around for the best price (UK)
The sensitivity of the 'old' XXLS(which I prefer) is 90 I think, and the bass output rises at around 60-150hz so I did think to rear fire the port and damp it abit. I'm trying to choose drivers which are all similar sensitivity but the Morel is 6 ohm, not sure if that is an issue.
what order x/o would you recommend at 300hz?

[PEB]

Impedance is always an issue, never truer than with 3-ways. The problem is that both the midrange and sub woofers have their minimum impedance in the 200Hz region. Keeping the cross point high-ish (~300Hz) may end up side-stepping the problem.

Also, your SPL model graphs will illustrate the ~1-decade bandpass for the midrange. I.e. 300-3000 Hz on the midrange is one decade in frequency. The midrange appears to never be flat. It is humped at 1k, but is rolling of on either side. That is normal.

Good summation is very important.

[Bill poster]

I will draw up the design tonight- I am thinking to split into 2 cabs per side. The cabinet for the Peerless drivers need to be pretty huge and I want a slim look, so to maximise the height I am placing the tweeter under the mid. Not sure what tweet to use, was looking at Scanspeak R3004 but its 4 ohm.