I have a cabinet building question ...

[PioneerGuy75]

When measuring driver parameters, what determines cabinet size and ported VS sealed etc?

My gut instinct is that Q is the biggest factor....Am I right?


Insight MUCH appreciated!!

 

[PioneerGuy75]

 

[PioneerGuy75]

Perhaps my first Question was too vague...

:scratch2::scratch2:

I shall try again...


I have two speakers that I would like to build boxes for. Here are the specs:

#1
Vas...............17.68L
Qts...............0.84
Qes..............1.08
Qms..............3.69





#2
Vas..........38.9L
Qts..........0.23
Qes.........0.29
Qms........1.24


Can someone direct me in the right direction please?


Also I have an Audax HD38S100 that I would like to find specs on.

Much Appreciated! :thmbsp:

 

[89grand]

Qts is the major factor in determining ported or sealed, many believe .4 is the mid point value, much below that is best used in a ported enclosure, much about that, sealed is best, and in the area around .4, give or take a certain amount, the woofer can be used in either. Vas has a lot to do with the cabinet internal volume.

Woofer 1 would belong in a sealed box and would exhibit some hump in the bass response unless the enclosure was quite large because of the higher Qts.

Woofer 2 would be ideal for a ported enclosure.

You can use WinISD online to get recommended enclosure volumes by plugging in those numbers along with Fs.

http://www.linearteam.dk/default.aspx?pageid=newdriver

 

[PioneerGuy75]

Would Speaker 1 work in an open baffle design?

Cheers

 

[PioneerGuy75]

I have been digging through WinISD... I see that for any given driver you can select closed or vented type box...

:scratch2:

I noticed that #2 (SEAS P17RCY) requires 4.3L sealed box and 5.6L vented box...Is this normal?

The vent sizing in there is really confusing me (calling for a 5" vent 36" long )

Sorry for the newb questions but i am still new to this!

:saywhat:

 

[Bobarazzi]

Check out this link: http://www.mh-audio.nl/spk_calc.asp

 

[GordonW]

Would Speaker 1 work in an open baffle design?

Cheers

Yes. In fact, it'll probably perform better in an OB, than in any other enclosure, due to the extremely high (above .707) Qts. You don't want to "load up" that speaker and increase the Q to an even higher level. An OB will essentially "leave it alone", with the Q of the system being the Qts of the driver itself. In an OB, the slight "hump" of the high-Qts driver may help, to "prop up" the bass that would normally be cancelled out, by front-to-rear driver interference (ala what Carver did in the Amazing Loudspeaker- high-Qts drivers especially made so that their peak "overcame" some of the open-baffle rolloff).

The second speaker looks to be intended for a vented or passive radiator enclosure.

Regards,
Gordon.

 

[elnaldo]

Specs of your Audax are here:

http://www.audax.com/archives.php

 

[michiganpat]

Would Speaker 1 work in an open baffle design?

Cheers

yes

 

[michiganpat]

I have been digging through WinISD... I see that for any given driver you can select closed or vented type box...

:scratch2:

I noticed that #2 (SEAS P17RCY) requires 4.3L sealed box and 5.6L vented box...Is this normal?

The vent sizing in there is really confusing me (calling for a 5" vent 36" long )

Sorry for the newb questions but i am still new to this!

:saywhat:

typically an optimized ported enclosure will be larger than an optimized sealed enclosure for a driver

reduce the diameter of the vent in the program and it should get shorter.

 

[PioneerGuy75]

typically an optimized ported enclosure will be larger than an optimized sealed enclosure for a driver

reduce the diameter of the vent in the program and it should get shorter.

So, roughly speaking, I can use most drivers in either enclosure design?

Vented boxes are generally bigger?

Thanks!!

 

[89grand]

So, roughly speaking, I can use most drivers in either enclosure design?

Vented boxes are generally bigger?

Thanks!!

I wouldn't say that exactly. If the Qts is pretty low, below say .30, it strongly suggests a vented enclosure otherwise bass response will be anemic. If it's pretty high, say above .5, it would perform best in a sealed enclosure, or you'd need some crazy long vent length. If vent length comes out too long for any speaker, maybe a passive radiator design is more fitting.

The thing with WinISD, is that it will show whatever it thinks is the best response for either enclosure, but that doesn't mean it really belongs in it. In other words, it will give you an "ideal" sealed enclosure volume for a speaker, even if it shouldn't be used in one.

Yes, vented enclosures are almost always larger than the appropriate sealed enclosure for any given speaker. That's why sealed enclosures are so much easier to build, find a speaker with a Qts around .6, and put it in the appropriate sized sealed enclosure. Vented enclosures have many more issues, such as vent length (which is directly tied to vent diameter) and so on. You can make the vent shorter, by making the diameter smaller, but then you run into port noise issues if it's too small.

 

[PioneerGuy75]

Thanks!!

 

[PioneerGuy75]

Been digging more.....

Let me see if I am getting this...

Main parameter to affect box SIZE is Vas?

Main parameter to affect box TYPE (Sealed vs Ported) is Qts?

Low Vas = smaller box that higher Vas right?

Qts <.3 ported, between .3 and .5 sealed box and above that IB or OB?

Thanks so much for advice. I appreciate if this seems newb but I am relatively new to building boxes and all these specs are not sinking in.

If anybody can recommend a good book that explains this in better detail, I am listening!


Thanks so much

 

[michiganpat]

QTS .3-.5 I'd say would work OK in either, .5-.7 or .8, sealed, >.8, IB

 

[elnaldo]

HI,

I was reading with interest all this explanations, and I don't want to add confusion here, but my WinISD suggest me a vented box for my woofer, Qts is 0.46.

The software says: "Use the vertical Efficiency Bandwidth Product (EBP) bar indicator as a guide to determine which box type is best suited for this particular driver.", and that indicator is definitely moved to the "Vented" side....

Is it any other parameter that determines the optimum enclosure type?

 

[PioneerGuy75]

Thanks