| mazeroth |
I always thought the smaller the box (higher Q) the tighter the bass. When reading about Shiva applications in the Shiva .pdf:
http://www.adireaudio.com/Files/Sea...pplications.PDF
It states that the lower Q boxes have tighter sounding bass. I always thought the larger the enclosure the less control the woofer had and would not be as tight. Hmm...have I been wrong all along?
Thanks! |
|
|
| simon5 |
Well according to Adire, tight bass is achieved with low group delay, under 20 ms.
If you look at the Tempest vented designs, they have 23 ms with Q 0.707, then 17 ms with Q 0.577.
If you look at multimedia market, Logitech Z5500 high Q 10 incher boom box versus Klipsch Promedia 5.1 Ultra dual 8 incher lower Q and tighter, you can see a good example.
But I think that Q is not the only factor for tightness. |
|
|
| BassAwdyO |
For sealed systems
Q<.5 - underdampened (Bigger)
Q=.5 - Critically dampened (perfect enclosure volume)
Q>.5 - Overdampened box (Smaller)
"tight" is a subjective term.
If the speaker is critically dampened it will be the most accurate and have the best impulse response. It will not resonate due to the airspring being too strong or weak. Accurate = Tight IMO |
|
|
| richie00boy |
| quote: | Originally posted by BassAwdyO
For sealed systems
Q<.5 - underdampened (Bigger)
Q=.5 - Critically dampened (perfect enclosure volume)
Q>.5 - Overdampened box (Smaller) |
Nope. The lower the Q the more damped the system is. The more damped it is the tighter it is said to sound. The lower the Q the bigger the box is.
Also, Q doesn't really start to get into underdamped territory until it goes above 0.7071. At this value the amplitude is maximally flat.
| quote: | Originally posted by BassAwdyO
"tight" is a subjective term.
If the speaker is critically dampened it will be the most accurate and have the best impulse response. It will not resonate due to the airspring being too strong or weak. Accurate = Tight IMO |
That's a reasonable assumption.
In essence Q is the only factor deciding tightness. However, directly related to Q are the amplitude and transient responses. A given Q will have a given size amplitude peak and specific transient response. A peaky amplitude response or a sloppy response to an impulse (transient) will make things sound less tight. Group delay is really an extention of phase and just tells us how 'in time' with the rest of the spectrum the sound is. |
|
|
| Mr Evil |
| quote: | Originally posted by richie00boy
...Also, Q doesn't really start to get into underdamped territory until it goes above 0.7071. At this value the amplitude is maximally flat.... |
Anything above 0.5 is underdaped by definition. At Q = 0.5, there will be no overshoot on transients. Above 0.5 there will be some overshoot, which is the very definition of underdamped.
I agree with simon5 that Q is not the only factor in "tightness". It's possible to have a high Q and still sound subjectively tight. It is also interesting to note that most people subjectively prefer Q around 1.0 because it makes the bass more punchy. |
|
|
| mazeroth |
What would you suggest for the Adire Shivas for me, a guy who listens to mainly rock and roll and heavy metal, with the occasional classical? I was thinking of going with sealed subs for stereo music (going to use with my line arrays that will be F3 ~70hz) and then also incorporate sonosubs for when I watch movies for all the LOW end. A few guys said good idea, a few guys said just make some nice sealed woofers and 30ish hz. will be low enough.
Discuss :D
Thanks! |
|
|
| richie00boy |
Personally, I'd just make one set that does well in both jobs. Then again I count space as being fairly premium.
You can usually count on some room gain to lift the low output so a good goal is to try and get your sub to around the point that room gain starts.
Frg = 344 / (longest dimension x 2)
assuming dimension in metres |
|
|
| simon5 |
Well mazeroth, did you look at the vented shiva PDF ?
I don't know how you like your sound. I like it flat and deep. I will build soon a ported box for a Shiva according to the EBS alignment in that PDF.
The room response is flat when corner loaded. ±1 dB 18 Hz-60 Hz @ 94 dB SPL 1W / 1m with a crossover at 80 Hz. For sure you can use another crossover to go higher than 60 Hz and stay flat. |
|
|
| planet10 |
| quote: | Originally posted by richie00boy
Frg = 344 / (longest dimension x 2)
|
Are you sure that formula is accurate... it gives 15 Hz for my room, and i'm certainly getting gain above that.
dave |
|
|
| richie00boy |
| Well... I had been using Frg = 344 / longest_dimension, but just recently I picked up on Bill Fitzmaurice claiming that gain begins at the point where the longest dimension is equal to a half-wavelength. To my ears it seems about right as my sub goes down to 24Hz anechoically and Frg calcs out about 32Hz for my room. The whole setup sounds fairly even to me and if I wind back the sub to match the higher Frg it seems to leave a bit of a null. I originally had the sub set up higher so it's not the case of being used to the extra bass. |
|
|
| planet10 |
| quote: | Originally posted by richie00boy
I had been using Frg = 344 / longest_dimension |
That would seem to match my empiracle results better.
dave |
|
|
|
