Does every tower need a port?

[Jukka]

Do ported designs actually win in absolute output? They're more efficient, sure, but judging by some random WinISD sims it seems that they have no advantage in max SPL when port volume is accounted for

Yes, ported design should give you better sensitivity for the same driver in the pass-band (above port tuning frequency) when compared to sealed. But below port tuning frequency the response drops way faster, sealed drops only about a half of that. How it exactly behaves depends on many factors, like box volume, the port(s) and front baffle shape. Which is better depends on how you plan to use it and where your tuning frequency is (cross over with subs? is it a sub? for music or movie rumble?).

To the OP: You should not expect loud and low bass from TMM 2- or 2.5-way. I'd go for a TMW 3-way. If you are using subs, you can make a 2-way and think of the subs as the third way, but then you need to choose the crossover point wisely and make sure it works out acoustically in your room. That can be a challenge. If your goal is to build small desktop speakers, you can tune lower as you don't need so much SPL.

 

[Jukka]

So in-regard to the tower, I've decided to go the sealed route. I'll be using 2 Dayton Audio DA175-8 7" Aluminum Cone Woofers paired with Dayton Audio ND25FA-4 1" Soft Dome Neodymium Tweeter.

I was using WinISD until I got to the point where I know the speakers wouldn't destroy themselves in the box together. I did try going the VituixCAD route, but all the material I'm finding is in regard to v1.0 and v2.0 is so different, that I've found it more frustrating than anything, so I've migrated to using XSim to start designing the cross-over.

I'm certainly open to using other software as well, these were just the first 2 that I could find online that were free and didn't seem too daunting. (though Vituix seems to have lost it's wizard which appears to have been a useful tool in v1.0)

I completely understand the steep learning curve of VCad. I've been using it so long time now I sometimes forget the pain of the early days
Nevertheless, VCad will allow you to simulate front baffle (ie. "baffle step" and edge diffraction) which is required for the crossover. You can simply iterate through it, but it's something you need to know where it comes from. Top tip: round the front baffle edges, it will greatly reduce unwanted diffractions.

The effects are something like this:

 

[manny11701]

I completely understand the steep learning curve of VCad. I've been using it so long time now I sometimes forget the pain of the early days
Nevertheless, VCad will allow you to simulate front baffle (ie. "baffle step" and edge diffraction) which is required for the crossover. You can simply iterate through it, but it's something you need to know where it comes from. Top tip: round the front baffle edges, it will greatly reduce unwanted diffractions.

You're gonna make me learn VCad when I DON'T WANNA :'(((

Lol, you do make a great point though. I mainly thought the purpose of VCad was just designing the cross-over, but I can see from your example that's not the case. I think I'll use XSim to get the crossover design down and then I can plug the components into VCad more easily, but it seems like VCad will give me the closest to realistic design that I can get before implementing everything IRL.

 

[manny11701]

To the OP: You should not expect loud and low bass from TMM 2- or 2.5-way. I'd go for a TMW 3-way. If you are using subs, you can make a 2-way and think of the subs as the third way, but then you need to choose the crossover point wisely and make sure it works out acoustically in your room. That can be a challenge. If your goal is to build small desktop speakers, you can tune lower as you don't need so much SPL.

This is also another great point/tips. I was planning on using a sub and then tuning at around 62hz - 65hz for the low-end. The two Mid-woofers have a decent range and they could get down to 31hz in a ported box, but I've just never been a fan of ported speakers.

I like things to have their purpose and the purpose of these bad boys is to just make some good-quality sound. My subs can handle the bass (granted this is a retail klipsch 10" ported woofer that I got for 50 bucks off a guy I know, but I want to take my audio challenges one step at a time

 

[beagleman]

Yes, ported design should give you better sensitivity for the same driver in the pass-band (above port tuning frequency) when compared to sealed. But below port tuning frequency the response drops way faster, sealed drops only about a half of that. How it exactly behaves depends on many factors, like box volume, the port(s) and front baffle shape. Which is better depends on how you plan to use it and where your tuning frequency is (cross over with subs? is it a sub? for music or movie rumble?).

To the OP: You should not expect loud and low bass from TMM 2- or 2.5-way. I'd go for a TMW 3-way. If you are using subs, you can make a 2-way and think of the subs as the third way, but then you need to choose the crossover point wisely and make sure it works out acoustically in your room. That can be a challenge. If your goal is to build small desktop speakers, you can tune lower as you don't need so much SPL.

Also, Sealed is not the same as acoustic suspension speakers.

I have owned several acoustic suspension speakers over the years, and you can get the SAME bass as a bass reflex, but usually at a bit less of sensitivity, due to the lower resonance frequency of the driver in free air, and the resultant longer excursion and voice coil.

Sealed is like a hybrid, not truly being reflex or acoustic suspension.

 

[Gringoaudio1]

Also, Sealed is not the same as acoustic suspension speakers.

I have owned several acoustic suspension speakers over the years, and you can get the SAME bass as a bass reflex, but usually at a bit less of sensitivity, due to the lower resonance frequency of the driver in free air, and the resultant longer excursion and voice coil.

Sealed is like a hybrid, not truly being reflex or acoustic suspension.

Huh?

 

[Astrozombie]

Now that i think about it I don't think I've ever seen a sealed floorstanding speaker.

 

[Doodski]

Now that i think about it I don't think I've ever seen a sealed floorstanding speaker.

I have. MB Quart made sealed floor standers.

 

[Jukka]

Now that i think about it I don't think I've ever seen a sealed floorstanding speaker.

I think all Magico speakers are sealed.

 

[Gringoaudio1]

Sealed is Not Acoustic Suspension in Loudspeakers

Some vented speakers offer port plugs for sealing the cabinet and making them act like sealed speakers. This does not result in a true acoustic suspension. What's the difference? Read on to find out.

www.audioholics.com

Interesting article to support beagleman’s claim that sealed isn’t necessarily ‘acoustic suspension’. I’m afraid ‘sealed’ is as close as we’re ever going to see to ‘acoustic suspension’ though.

 

[moonlight rainbow dream]

Isn't it just semantics? Acoustic suspension are all sealed AKA closed speakers. Sealed is the general category; acoustic suspension falls within that. Infinite baffle is also technically sealed just on the opposite side of the spectrum. Acoustic suspension means that the sealed enclosure is small enough that the air spring effect is much stronger than the suspension of the driver itself.

 

[Gringoaudio1]

Isn't it just semantics? Acoustic suspension are all sealed AKA closed speakers. Sealed is the general category; acoustic suspension falls within that. Infinite baffle is also technically sealed just on the opposite side of the spectrum. Acoustic suspension means that the sealed enclosure is small enough that the air spring effect is much stronger than the suspension of the driver itself.

That’s what I would have thought. This article claims a difference. Speaker suspension is made of something and is always going to affect some spring force but this piece claims that a true Acoustic Suspension would have a speaker surround that was not in the equation. Not sure of the credentials of the writer.

 

[Ron Texas]

Ever ship needs a port.

 

[eboleyn]

So I've decided on going with a sealed tower and will be pairing it with a sub that will cross over at 60hz. I just had a question about cubic feet in an enclosure:

When using 2 drivers in a sealed enclosure, do you simply double the sealed volume to build your box? can you go bigger and it be safe or is it better to stick to the suggested .35 cubic feet for 1, .7 cubic feet for 2 speakers in this instance for the Dayton Audio DA175-8? My TFM is looking attractive in WinISD with 1.8 cubic feet, but there's a hump when I use the recommended cubic feet.

... (diagrams deleted for brevity) ...

If you're really planning on a TMM (or any repeated driver design, MTM can also apply), you should consider that repeating drivers near each other can give frequencies an extra non-intuitive boost (typically considered +3db for each doubling of drivers, for frequencies where the drivers are within 1/4 wavelength of each other) above any other considerations like running them in parallel, so for example, ideally you get +6db total for paralleling 2 drivers of the same type right next to each other, or +3db at the same power.

I only really came to understand about this recently myself, after having seen some anomalies in previous speaker measurements with multiple drivers. WinISD doesn't show you the effect.

So for example, I'm looking at making a design with the following stats:

• Line array with 6 identical 6.5" drivers (can be spaced 7" center-to-center when the edges are considered)
• Total height of drivers, about 42".
• A big ribbon tweeter off to the side, crossed at about 2kHz.

The results are supposed to end up being something roughly:

• low frequencies up to about 100 Hz, I'll get a +7.75-ish db boost.
• going down to about +6db at 160 Hz.
• going down to about +3db at 500 Hz.

Regards,
Erich

 

[mhardy6647]

Now that i think about it I don't think I've ever seen a sealed floorstanding speaker.

heh-heh-heh.
Never ran across a pair of AR-9 (e.g.), eh?

Revisiting the Acoustic Research AR9 4-Way Legendary Loudspeaker

In 1978, Acoustic Research introduced the AR9, a brand-new, four-way loudspeaker system. Read on to see how the AR9 was conceived and why it is considered to be the most influential speaker ever.

www.audioholics.com

Or, say, a pair of Allison Ones?

Allison One Series Brochure (1978) | The Classic Speaker Pages

Sorry to hear that.