Does every tower need a port?

[manny11701]

Let's hope your determination and love of a challenge doesn't falter when you reach the crossover design

I gotta get the box figured out first, but we’ll get there

 

[Bach]

Let me guess: you will opt for a two way basreflex with a 7 inch woofer and an 1 inch tweeter, which you can get with a big discount from a local dealer. An already soldered ( some skills are so boring) crossover comes from a supplier abroad. For the cabinet a free of charge exact cut set of panels will be used; for the finish a water based eco friendly paint is prefered. The result will, of course, even surpass your, in advance defined, high demands! And to be mainstream, one or two(!) subs will eventually added.

 

[manny11701]

Let me guess: you will opt for a two way basreflex with a 7 inch woofer and an 1 inch tweeter, which you can get with a big discount from a local dealer. An already soldered ( some skills are so boring) crossover comes from a supplier abroad. For the cabinet a free of charge exact cut set of panels will be used; for the finish a water based eco friendly paint is prefered. The result will, of course, even surpass your, in advance defined, high demands! And to be mainstream, one or two(!) subs will eventually added.

Wow, my next steps have already been planned out for me! Phew, that's some time that I can save!

I will say that I did have to google what a basreflex was and unfortunately I am going for a sealed tower, so maybe for a future project? It does sound like you must have gone down this route before, so maybe we can work together when I finish with this one!

 

[Prana Ferox]

You can DIY whatever you want for whatever reason you want. It's your time, money, effort. Go nuts!

People generally gravitate to towers (or 'monkey coffin' bookshelves, vice the more compact ones in fashion) expecting reference volume bass extension without subs. To get that extension, you're going to need big LF drivers, many LF drivers, ports, or a combination of those.

Keep in mind that ported vs sealed is part of selecting your woofer (or built-in subwoofer) because some drivers will work better sealed vs ported (where 'better' in this case usually means "picking wrong requires an unrealistically enormous box"). Randomly googling reveals:

A parameter called EBP (calculated by dividing FS by Qes) is often used to determine if a speaker is best suited for a sealed or ported enclosure. An EBP close to 100 usually indicates a speaker is best suited for a ported enclosure. An EBP closer to 50 usually indicates a speaker is best suited for a sealed enclosure

WinISD will also make recommendations based on that.

 

[manny11701]

You can DIY whatever you want for whatever reason you want. It's your time, money, effort. Go nuts!

People generally gravitate to towers (or 'monkey coffin' bookshelves, vice the more compact ones in fashion) expecting reference volume bass extension without subs. To get that extension, you're going to need big LF drivers, many LF drivers, ports, or a combination of those.

Keep in mind that ported vs sealed is part of selecting your woofer (or built-in subwoofer) because some drivers will work better sealed vs ported (where 'better' in this case usually means "picking wrong requires an unrealistically enormous box"). Randomly googling reveals:

WinISD will also make recommendations based on that.

Thanks Prana! Appreciate this! I was actually looking up drivers in my price range and plugging them in randomly to see how close to good I'd get, but this should help save me some time!

 

[droid2000]

Have you guys come across any literature that a layman could understand for sizing ports?

The kit speakers I built have an adjustable port and I'm wondering what effect changing it would have.

 

[fpitas]

Have you guys come across any literature that a layman could understand for sizing ports?

The kit speakers I built have an adjustable port and I'm wondering what effect changing it would have.

Everybody uses calculators now. WINISD, AJ vented etc.

 

[mhardy6647]

Have you guys come across any literature that a layman could understand for sizing ports?

The kit speakers I built have an adjustable port and I'm wondering what effect changing it would have.

It's very simple, actually -- it's arithmetic, not maths!
The physics of a box (container) with a hole in it can be found under the moniker of a Helmholtz resonator.

If you're curious, seek out one of Ray Alden's (old) books. I find his treatment of loudspeaker design basics to be accurate and easily digestible.
See if you can find a copy of his book Speaker Building 201.
That said, go with @fpitas's advice & use a calculator.

 

[droid2000]

It's very simple, actually -- it's arithmetic, not maths!
The physics of a box (container) with a hole in it can be found under the moniker of a Helmholtz resonator.

If you're curious, seek out one of Ray Alden's (old) books. I find his treatment of loudspeaker design basics to be accurate and easily digestible.
See if you can find a copy of his book Speaker Building 201.
That said, go with @fpitas's advice & use a calculator.

Thank you so much. This is the info I needed to get started. Mucho gracias!

 

[mhardy6647]

FWIW, I am not too crazy about the volumes (updates) of the Loudspeaker Design Cookbook written by Vance Dickason.
They are (or at least were, when I was big into DIY loudspeaker enclosure design) very popular. My issue with Loudspeaker Design Cookbook is just that. It's a collection of recipes. It tells one what to do, but doesn't really do much to help one understand why. There are actually a number of good books for non-specialists on loudspeaker design, but I like Ray Alden's as striking a good balance between the purely practical and the "theoretical" (i.e., enough math, presented with enough context, to help one understand why). YMMV, of course.

 

[Vineeth Kumar V]

Interesting way to use DSP assist in a bass reflex system

The DSP Assisted Reflex System - Squeeze More Bass from Every Reflex Design

Vented systems are in chronic overload. This article shows how, by applying low-cost digital signal processors (DSPs) to passive radiators, you can extend bass an octave below what is normally considered practical. At the same time you can increase power handling and maximum output, and squeeze...

audioxpress.com

 

[manny11701]

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.

 

[fpitas]

Yes, double volume for two drivers. I like to tune sealed woofers for no hump, about a Q = 0.7. Some people like the hump, but if you're using a sub I doubt you want it.

 

[moonlight rainbow dream]

WinISD should allow you to model using multiple drivers. Maybe try grabbing the latest version?

 

[manny11701]

Yes, double volume for two drivers. I like to tune sealed woofers for no hump, about a Q = 0.7. Some people like the hump, but if you're using a sub I doubt you want it.

I see what you mean, the SPL looks a lot better with a Q =0.7. Thanks for the tip, it's been a big help!

@moonlight rainbow dream, this version does allow for multiple drivers, though I didn't realize that there were more current versions of WinISD, I'll take a look! Thanks! When I googled around this was all I could find.

 

[Prana Ferox]

Keep in mind that, that far down in the bass, your nice pretty response curves are heavily at the mercy of room response. Woofers tend to measure a bit different from each other. And your cabinet volume will be affected by bracing, space taken up by the drivers, etc. which can be hard to calculate precisely. So don't get too hung up on getting the perfect WinISD response.

 

[Jukka]

I’ve loved hifi audio and have only recently been intrigued with building my own speakers.

I’m currently designing a pair with a TMM orientation, but one thing that I’ve noticed is that almost all tower speakers in the retail market have a port. Is this necessary to design a good tower speaker?

I’m still playing around with winISD, but another thing I noticed is the ports tend to be quite large on retail towers, but I the program if you use a larger port, it typically also has to be longer, so does anyone know they they’re circumventing this? (I’m assuming the internals are likely a transmission style box.

There is a large number of things to get right and WinISD doesn't simulate even half of them. I'd prefer a better app, like VituixCAD. Anyway, if you're new to DIY, I'd suggest to try an existing DIY design or a complete kit. These are easy to find.

Tuning frequency of a port is the ratio between cross section area and length of the tube. If you enlarge diameter, you need to lengthen the tube to retain the same tuning frequency. Too small diameter will cause higher air speed in the port and lead to unwanted port noises. Your simulator should warn you about this at the SPL you are aiming to. Air volume of the port eats away internal volume of the box, so add that to your calculations.

 

[Jukka]

The port provides better low frequency performance in a given size cabinet. Since the cabinet is very expensive to make an overwhelming number of speaker manufacturers use ported enclosures.

Cabinet material cost is the lowest in speaker parts. Maybe the screws or wiring is lower, but no body says "the wiring inside tall speakers is so expensive that you shouldn't build tall speakers". It does take time and skill though, if using paid carpenter/service.

 

[JayGilb]

Great thread with a lot of useful information. Above all - have fun and make it a learning experience.

 

[manny11701]

There is a large number of things to get right and WinISD doesn't simulate even half of them. I'd prefer a better app, like VituixCAD. Anyway, if you're new to DIY, I'd suggest to try an existing DIY design or a complete kit. These are easy to find.

Tuning frequency of a port is the ratio between cross section area and length of the tube. If you enlarge diameter, you need to lengthen the tube to retain the same tuning frequency. Too small diameter will cause higher air speed in the port and lead to unwanted port noises. Your simulator should warn you about this at the SPL you are aiming to. Air volume of the port eats away internal volume of the box, so add that to your calculations.

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)