Stretching bass down in 2-way

[alspe]

Is there any weakness's if 2-way speakers is designed to produce quite low bass? First thing to stretch bass down is choice of right driver (low Fs, Qts around 0,33-0,40) and use it ported. Usually sensitivity gets lower as bass goes deeper, physical fact. That's a weakness..

What I've simulated, in room 25 Hz is achieved by some ScanSpeak 18e/8531G00 for example. About 25 litre floorstander and you can tune port at bottom, so quite long port in enclosure is no problem. You can use enough big port so air velocity makes no problem. 25 Hz with simple 2-way is not bad at all.

Has this design only pros? Lower bass, lower group delay, better "shielding" against infra frequencies by port output. Any cons? I have heard that too high Qts driver tuned low and you might get sloppy bass.

[Charles Darwin]

IME the lower a two way goes the more its mid-range suffers, due to intermodulation I guess.
The mid range in my 2ways improved quite a bit after I added a 3rd way woofer to take over below 175Hz.

[alspe]

Originally Posted by Charles Darwin

IME the lower a two way goes the more its mid-range suffers, due to intermodulation I guess.
The mid range in my 2ways improved quite a bit after I added a 3rd way woofer to take over below 175Hz.

Did you convert to 2,5way or 3way?

Intermodulation is due the cone movement, cone movement could be shorter when speaker is tuned lower. Although bigger box allows larger excursion. Only way to avoid intermodulation is to use 3-way or 4-way (or 5-way). Don't go there in this topic.

Discussion of box size and tuning in 2-way, please.

[rvrazvan]

Maybe crossing very low, and using a fullrang driver, or an AMT for the upper band?

[ODougbo]

I use vifa 7" /Morel MD30 - 2 ways in the HT, they go extronary low. I build a pair for my buddy's HyFy stereo, and they have great midlle also.

They don't make the 7" M18WO-09-08 anymore, but the Scan-speak Discovery 18W/8434G is a new fiberglass version with a much better upper frequency response - reportedly.

The mid bass speaker mentioned, looks very nice!

[bbggg]

After perusing and researching Salas' work on the "Tired2way", I have pretty much settled on the Volt BM220.8 as a suitable 8" with good bass extension and high midrange performance. The search for a suitable tweeter continues, although a good, sturdy one with a shallow waveguide seems to be just right. The Monacor DT-300 with its companion WG-300 waveguide looks good so far. Crossed at around 1200-1500 Hz, such a system should be able to play clean, loud and low, as low as 35 Hz maybe, in a vented 35-45 liter box.

[dirkwright]

Originally Posted by rvrazvan

Maybe crossing very low, and using a fullrang driver, or an AMT for the upper band?

Yeah, there you go. Use a good quality full range driver for the upper octaves, and use a small subwoofer for the bass. Crossover at something really low (for a 2 way) like 500Hz. I'm playing with this idea now for some bookshelf speakers.

[sreten]

Originally Posted by alspe

Has this design only pros?

Hi,

Pretty much the case but there are a couple of caveats. Tuned higher with
a sub vent filter will have higher power handling if volume capability is an
issue. Freespace placement with unequal distances will help room gain
compensate for the earlier bass roll-off. Best tuning frequency is
optimising for f-6, f-9 or f-10. Don't make the boxes too big.

The Scanspeak 15W/8434G00 is fs-50Hz, Vas -19.5L and Qts 0.43.
Classic F-3dB tuning is 25L tuned to 47hz.
Optimising around f-9 and f-10 gives a tuning around 30Hz,
going for f-6 around 35Hz, so 30 to 35 Hz is low tuning.
All things considered 33Hz tuning in 25L looks the best to me.

rgds, sreten.

[dirkwright]

Originally Posted by bbggg

After perusing and researching Salas' work on the "Tired2way", I have pretty much settled on the Volt BM220.8 as a suitable 8" with good bass extension and high midrange performance. The search for a suitable tweeter continues, although a good, sturdy one with a shallow waveguide seems to be just right. The Monacor DT-300 with its companion WG-300 waveguide looks good so far. Crossed at around 1200-1500 Hz, such a system should be able to play clean, loud and low, as low as 35 Hz maybe, in a vented 35-45 liter box.

That tweeter won't handle crossing over at 1200-1500Hz. You need a horn to get that low. I used the B&C DE250 + ME30 to cross over at 1600Hz in another speaker. You'll have to get something bigger to go lower.

[rob g]

Originally Posted by dirkwright

That tweeter won't handle crossing over at 1200-1500Hz. You need a horn to get that low. I used the B&C DE250 + ME30 to cross over at 1600Hz in another speaker. You'll have to get something bigger to go lower.

Or go active and use a 2 inch fullrange, like the Aura Whisper.
Aurasound NSW2-326-8A-120 2" Full Range with Solder Pads: Madisound Speaker Store
Great when equalized well, like the Linkwitz Pluto.

Meridian have also recently produced a new active (what else?) two way standmount with ultra low crossover frequency with an unusually large 85mm treble unit.
DSP3200 Digital Active Loudspeaker - Meridian