what is it? is it better to have a low q or high?

Which Q?

in the driver paremeters for a sealed enclosure a .66 sizes gives a q factor of 0.707 a 1 ft sixe gives a q factor of 0.589. What is a q factor?

the menu:

Qts

Qes

Qms

or Box alignment Q (used for decribing sealed box low frequency characteristics)

i would think that he is refering to the q of the box

just missed your post... [img]tongue.gif[/img]

Ok, what you are looking at is a value for comparing the driver's resopnse before rolling off.

A value of 0.707 is considered perfectly flat frequency response wise with a 12db/oct low freq. roll off rate.

A value of 0.59 is going to have a less pronounced low frequency roll off (it will sound deeper) but will have less midbass punch to it.

A value of 1.0 is widely popular in car audio due to it's enherent punch or boost in the midbasss region. This gives a stronger amount of kick on music transients, but less low end extension.

so a choice between the two if you had it would be the .707? Sorry still trying to understand

There is cabin gain to consider here as well.

What PEI describes is a side effect of box Q, IMO..

The total Q for your woofer system describes the compliance of the driver in the box...

A higher Q will have better transient response... (better accuracy, 'tighter' sound) a lower Q will give you a sloppy boomy sound...

As PEI mentioned, this is directly related to the frequency response of the box with a given woofer as well...

If I were you I'd stick with .707 [img]graemlins/thumb.gif[/img]

[ November 22, 2004, 06:36 AM: Message edited by: Haunz ]

I thought it was the other way around.

[ November 21, 2004, 12:42 PM: Message edited by: Seahag ]

Maybe you are right?

No I think lower Q = more compliance..

[ November 22, 2004, 07:40 PM: Message edited by: Haunz ]

so lower or higher q?

Q(tc) = 1.0 This frequency response corresponds to the smallest box of interest.
It has a slightly peaked response.
Q(tc) = 0.707 This is a Butterworth alignment which has the flattest possible frequency response.
http://www.trueaudio.com/about_2.htm

[QUOTE]Originally posted by Jeepbeats:
[QB] Q(tc) = 1.0 This frequency response corresponds to the smallest box of interest.
It has a slightly peaked response.
Q(tc) = 0.707 This is a Butterworth alignment which has the flattest possible frequency response.

Iam not sure what all of that means, learning as I go

I`m not sure either.

I had a tempest in a small box and it sounded flabby. After investigating, the problem was cause by the small box. I would have thought different.

Still dont know for sure.

It's hard to relate the Q-factor of a woofer system to it's dynamic properties..

A 15 in a huge box with a Q of 0.65 MAY not sound as tight and snappy as an 8 in a small box with a Q of 1.0 or higher.

I usually suggest something around 0.80-0.85 for most people, unless they need to handle a lot of power, then I'll shrink the box for a Q of 0.95 to 1.0.

For me, I'd choose a driver that sounded good, then drop aim for 0.707 or so.. But I am into low, over loud...

Most people attribut loud boomy bass to good bass, so they want a small box.

^ 'boomy' might be a subjective term.. but if you want louder unaccurate bass you want a larger box... ;)

i built a box .66 ft3. 12x12x12 3/4 mdf. I amlooking for sq and space is an issue that is why i chose sealed. As far as the question goes I see it is not an easy answer but it seems to me most are saying higher q is better for sq.

I guess it comes down to what you like.
The only way to find out is to build different boxes.

Now here is a thread full of misinformation.

How so?

Derek is so right.. It's really a matter of perception with respect to damping or what is deemed as 'more accurate'.

The Total Q of a system only describes the predicted small-signal response, low frequency cutoff and gain of a woofer, based on a set of thiel small parameters.

What the bass sounds like is another topic.

Exactly, and if you just ported the damn thing it would sound so much better anyway [img]graemlins/dunno.gif[/img] [img]graemlins/thumb.gif[/img]

my input - low q for tigter response
use low q to hit the freq's that you want to really HIT.

low q, high q, everyone has differences, i guess I just have to find out myself. Is anything straight forward?

Thanks for all the input!

Thanks for that insight DW and dave... [img]graemlins/2xblown.gif[/img]

yea, things are a little diff when you deal with large signal... but don't tell me you guys use something other then small signal parameters when you design a box... ?

Even with large signal, as long as the sub is linear, params aren't going to change that much anyway.. ;)

EDIT: your car sure does effect how your box will sound.. so these guys do have a point there... its all relative...

Edit2- here is a site that explains Q a little better then I could about 2/3 down http://www.ht-audio.com/basics.htm according to it i've been correct about Q and transient response...

[ November 22, 2004, 07:34 PM: Message edited by: Haunz ]

You're welcome Haunz [img]graemlins/blah.gif[/img]

Anyways a lower Q, less than .7 is considered underdamped, and a higher Q such as 1.0 is considerecd overdamped. Whether one is "toiter" than the other is a matter of opinion about what the definition of "tighter" is. In any case the same sub in the same car, a larger box would have a lower Q and would have more extension than a smaller box that would have a higher Q and would sacrifice extension for power handling.

Can't you just feel the love.. [img]graemlins/laugh.gif[/img]

Now I know why I took a vacation from this place...

Very few people have access to large signal test equipment. In fact, I don't know for sure, but I think only LEAP 5 has the ability to handle driver non-linearities in determining output at high levels. Thanks to Klippel and LMS though, things are becoming better in that regard.

LEAP 5 and LMS work really well together Dave. With a couple of simple parameter tests using the impedence function of LMS, you can get LEAP 5 to just about dial in the next winning lottery ticket #s.

[img]smile.gif[/img]

My LMS arrives shortly... [img]graemlins/jammin.gif[/img] :D :cool: [img]smile.gif[/img]

I'm still old-school with Leap 4 though... No money left to bump to 5.. maybe with some more private and prototype reviews for different companies...

[ November 22, 2004, 10:38 PM: Message edited by: Dave_MacKinnon ]

^ so what do you expect people to design there boxes with ??

I guess if you only have a small parameter model you are totally wasting your time... :rolleyes:

Dave, you are going to love LMS 4.X

This is truly sad to say, but I don't bother much with spending time designing boxes. I model them in a sheet I created and aim for a target Fs or Qts, the drop 'em in the trunk and see if I like it.

Small signal parameters are great and do a good enough job predicting the output. Just saying that it's not the end-all be-all of determining what is going to happen. Imagine if the SPL guys could predict power compression and cone pressures in their vehicles?

The LMS is for the speaker design and prototyping side of things. Determining what the specs are basically.

^ Dave - you sound like me. I used to pour over box programs to no end, changing the smallest details until it was "perfect"

Now, I hit what I consider to be a good balance of volume, F3, vent length, and excursion and I'm done. Generally, it takes longer to enter in the T/S specs. [img]tongue.gif[/img]

Results are the same - I jsut have more free time.