View Full Version : How to compare subs using TS params?
gamiller
02-25-2003, 08:53 PM
Since I can't listen to every recommended sub, I have to resort to data sheets. I looked up what all the Thiele-Small parameters mean, but they seem to only be used to determine enclosure size. Can they be used to compare subs?
To my knowledge you are correct. The Thiele-small parameters are usually plugged into a software program and out comes the recommended enclosure type and size. I don't really see how that would help you in picking the sub. My theory on the sub question is this: You can go the spl route and hit hard with out too much regard for what it sounds like, or you can basically buy a sub that will round out the music. Me I'm running a 12 in Audiomobile which I'm happy with, but am looking into replacing it with two 8 in. or 10 in. subs. I prefer my subs to hit fast and respond quickly to the bass line. I love the tight quick bass if you know what I mean. That is hard to achieve with a bigger sub simply because the cone has more mass and can't respond as quickly as a smaller lighter sub. Sure you loose some low frequency end, but it's all a compromise. Good luck with the sub search.
Keane
02-27-2003, 12:34 PM
Originally posted by: xman
.....[snip].....Me I'm running a 12 in Audiomobile which I'm happy with, but am looking into replacing it with two 8 in. or 10 in. subs. I prefer my subs to hit fast and respond quickly to the bass line. I love the tight quick bass if you know what I mean. That is hard to achieve with a bigger sub simply because the cone has more mass and can't respond as quickly as a smaller lighter sub. Sure you loose some low frequency end, but it's all a compromise. Good luck with the sub search.
This is a common misconception. Smaller diameter subwoofers are not "quicker" than larger diameter subwoofers. A subwoofer with a higher mass cone is nearly ALWAYS found to have a correspondingly larger magnet, which allows the subwoofer to control that higher mass cone just as effectively as a smaller diameter subwoofer would.
The real true way to get responsive bass is to optimize the transition from your midbass (5-1/4" or 6-1/2") speakers to your subwoofer. That is typically accomplished through adjusting the crossover points of midbass speakers and subwoofer, adjusting the slope of the crossover, adjusting amplifier gains, adjusting equalization (if available) and, lastly, adjusting phase (if available).
Before you run out to spend money on new equipment, you might want to spend some time trying to fix what you already have.
Good luck.
Well then looks like I'm going to be doing some tunning this weekend. MY front stage are JL audio 6.5 XR components and they get music from ~80 hz up. The sub gets 80hz and down and the slope of the crossover is 12db/octave although I have the option of changing it to 24db/octave (Jl 500/1 amp). I'm fairly sure my gains are set properly although I don't have a scope to really be sure. That leaves my alpine eq and the phase of the sub I can mess with. I'll see what I can do if not Keane will have to give me some more input.
gamiller
02-27-2003, 05:16 PM
hmmmm. midbass.
how can i find out the low-end frequency rolloff for my 3-ways? it's not posted at pioneer. is there a FAQ on crossover freq?
Keane
02-27-2003, 05:33 PM
Originally posted by: xman
Well then looks like I'm going to be doing some tunning this weekend. MY front stage are JL audio 6.5 XR components and they get music from ~80 hz up. The sub gets 80hz and down and the slope of the crossover is 12db/octave although I have the option of changing it to 24db/octave (Jl 500/1 amp). I'm fairly sure my gains are set properly although I don't have a scope to really be sure. That leaves my alpine eq and the phase of the sub I can mess with. I'll see what I can do if not Keane will have to give me some more input.
.... more input, coming up....
Here (http://www.adireaudio.com/tech_papers/woofer_speed.htm) is a link to a white paper at Adire Audio's website on the very topic of "fast" or "slow" subwoofers. It's good reading.
As for your scenario, don't forget that sometimes you can get better sound by overlapping or even gapping your crossover points (when available with your specific equipment). Also be careful to only change one variable at a time as you are testing to see what sounds better to your ears.
Good luck.
Keane
02-27-2003, 05:40 PM
Originally posted by: gamiller
hmmmm. midbass.
how can i find out the low-end frequency rolloff for my 3-ways? it's not posted at pioneer. is there a FAQ on crossover freq?
If you aren't using some sort of active crossover, either through your headunit (some headunit's include an adjustable highpass for front & rear outputs) or through some sort of pass through arrangement on an amplifier, you probably do not have a highpass frequency set to cut the low end on your component set. That means you are giving them a full-range signal, and the midbass driver will try to play all the way down to 20Hz, with varying degrees of success. Most drivers will exhibit a 6dB to 9dB natural rolloff, starting at their given F3 point. You may be able to find the F3 (frequency at which the output is down 3dB) but you will probably only find the Fs (natural resonance frequency).
If you are powering the component set from an amplifier (I hope you are), you may have a high-pass crossover on the amplifier. That crossover may be adjustable, either infinitely adjustable between two given frequencies or it may only be selectable between two or more set frequencies. A good general break point between midbass and subbass is anywhere from 80-100Hz. Experiment with it to see how the sound changes and what sound you like best. Remember, the only ears you have to please are your own.
Good luck.
gamiller
02-27-2003, 05:46 PM
Originally posted by: Keane
Most drivers will exhibit a 6dB to 9dB natural rolloff, starting at their given F3 point. You may be able to find the F3 (frequency at which the output is down 3dB) but you will probably only find the Fs (natural resonance frequency).
Experiment with it to see how the sound changes and what sound you like best. Remember, the only ears you have to please are your own.
yeah, i guess i'm concentrating too much on the technicals, which doesn't help a bit if the specs aren't available.
oh, and keane, you might be pleased to know that i'm going with your original recommendation (autotek mono amp, adire shiva) for my setup. :)
Keane
02-27-2003, 05:50 PM
Originally posted by: gamiller
.....(snip).....you might be pleased to know that i'm going with your original recommendation (autotek mono amp, adire shiva) for my setup.
I'll be pleased when you tell me that you're happy with the sound..... ;)
Holy crap I almost had to take out my old physics book for that read. Still good stuff, thanks man. I learned something new today.
gamiller
02-27-2003, 11:10 PM
Originally posted by: xman
Holy crap I almost had to take out my old physics book for that read. Still good stuff, thanks man. I learned something new today.
yeah, me too. i thought the inductance only had to deal with the upper frequency cutoff rather than the reactivity of the sub.