What do box losses sound like?

[Apfelsauce]

Just curious... The title sort of says it all. I just built some mini-towers that are sort of roughly assembled, and should feature some significant losses around the baffle and rear panel that allows access to the crossover. Before I solidify everything by gluing it all up and reducing losses as close to nil as I can get them, I thought I might try to hear (but not test) exactly what losses sound like in a sort of before-and-after situation.

(I know Vance Dickason touches on this briefly, but he didn't pay a grad student to write an index for him, and I don't think even if I found it I'd get a simple enough answer to understand... Thanks!)

[AEIOU]

Originally Posted by Apfelsauce

Just curious... The title sort of says it all. I just built some mini-towers that are sort of roughly assembled, and should feature some significant losses around the baffle and rear panel that allows access to the crossover. Before I solidify everything by gluing it all up and reducing losses as close to nil as I can get them, I thought I might try to hear (but not test) exactly what losses sound like in a sort of before-and-after situation.

(I know Vance Dickason touches on this briefly, but he didn't pay a grad student to write an index for him, and I don't think even if I found it I'd get a simple enough answer to understand... Thanks!)

Vance talks about it in his book LCD 7th Edition, page 67. It relates to bass reflex alignments. Losses affect the amount and tuning of the bass. Excessive losses equals loss of bass. How does it sound? Unknown. Minimize losses and you'll obtain the maximum bass possible.

[AllenB]

You are referring to leakage, not losses. In the extreme leakage case you have the dipole speaker which is basically the front baffle on its own. They are reasonably popular.

[AEIOU]

Originally Posted by AllenB

You are referring to leakage, not losses. In the extreme leakage case you have the dipole speaker which is basically the front baffle on its own. They are reasonably popular.

Losses can occur if there is too much damping material inside the enclosure and/or if the port-vent is blocked or too small.

[TerryO]

An aperiotic design relys on loss to damp the impedence curve among other things.

Best Regards,
TerryO

[MCPete]

What type of system are your mini-towers? If closed-box (sealed), then large losses could result in Qtc lower than expected. That is,

Qtc = Qts*sqrt(alpha + 1)

holds true only if

(Qmc/Qec) = (Qms/Qes)

The above is rarely the case as every enclosure introduces some losses. Losses diminish Qmc. So unless Qms >> Qes, you can expect that the actual value of Qtc is less than the target value. Further then, f3 is higher than expected.

Regards,
Pete

[MCPete]

What do box losses sound like?
Just curious... The title sort of says it all. I just built some mini-towers that are sort of roughly assembled, and should feature some significant losses around the baffle and rear panel that allows access to the crossover. Before I solidify everything by gluing it all up and reducing losses as close to nil as I can get them, I thought I might try to hear (but not test) exactly what losses sound like in a sort of before-and-after situation.

So what I'm saying in my previous post is that (assuming that your mini-tower is a closed-box system) before solidifying most likely you will hear the leakage loss as less bass response and tighter transient response. Of course the characteristics of a closed-box system change gradually with the amount of loss, so it all depends on how leaky your boxes are, what value of Qtc you intend the design to be, and the ratio of mechanical Q (Qms) to electrical Q (Qes).

-Pete

[Apfelsauce]

Originally Posted by MCPete

So what I'm saying in my previous post is that (assuming that your mini-tower is a closed-box system) before solidifying most likely you will hear the leakage loss as less bass response and tighter transient response. Of course the characteristics of a closed-box system change gradually with the amount of loss, so it all depends on how leaky your boxes are, what value of Qtc you intend the design to be, and the ratio of mechanical Q (Qms) to electrical Q (Qes).

-Pete

Thanks Pete. It's a vented box. I don't have a good enough reference point, I don't think, to figure out at this time what are flaws in the design and what are box losses/leakage. I'll glue 'er all up and go from there!

[Don Hills]

Some programs such as Unibox alow specifying different amounts of "box leakage" so you can get an idea of how much effect leakage will have on a given box design.

[AllenB]

Whilst I think this cardboard cabinet has potential and is very interesting, I think your main concern might be the frequencies where the basket of the driver resonates with the baffle so that some sound gets lost. In other words, the speaker wont see a solid mounting at some frequencies and energy may be lost. This won't necessarily be in the bass and if it is, won't necessarily have anything to do with the enclosure volume.

Fortunately, this would probably show up in measurements. It should also be easy enough to alleviate by bracing the front baffle etc.