Discussion on Group Delay and Phase Response

[bassfreak]

it simply depends what your tring to do, a great designer can make 6th order sound great.
if you want a high output system with a wider flatter response ported..
if you want a system capible of getting low enough for rock jazz etc and something easier to tweek sealed..
a great souunding sealed box woofer just doesn't have the dampening a ported box requires.. ported is tricky.. port placement can make a big difference in some applications..
thats where transmission lines come into play..

[Lycan Audio]

Wow. I was beginning to lose hope in this thread and chalked it up to "I was too technical, oops." But you guys really came through on some interesting points. I see we got into the inevitable ported vs. sealed transience conversation.

Jimi177, your 1-5 rundown of favorable ported enclosure features matches what I've learned from selling hundreds of custom enclosures on the market over the years. I'd have to say it's close to 80% ported, 18% sealed and 2% bandpass. (Oh for the love of god let's leave bandpass out of this discussion, I'm saving that for a special thread!

I'm going to continue to believe that GD is a strong indicator to the SQ of a system. I'll assume that, aside from varying scientific studies, the threshold for noticing delay problems is different from ear to ear. It's pretty well established that some have more properly tuned ears than others

Thanks for a great discussion guys.

Look out for my new thread, where I will shift this conversation over to phase shift since it was lightly mentioned here. (I love puns!).

[bassfreak]

3) Ported enclosures work great for hip-hop, rap, pop, techno and other types of music with "artificial" bass. In other words "boom" sounds like "boom" even if the system is peaky. OTOH for a classic music listener or somebody who listens to traditional jazz music, the peak colors the sound of bass instruments, bass guitars in particular. Heavy metal with fast electric bass often turns to mud with ported enclosures.

you failed to properly design a ported box or your using the wrong woofer.
many many times ive hear ported alignments sound more transiant than sealed..
9 outta 10 your hearing the muddyness from the lack of mechanical dampening..
to this day very few subs id or sealed sound aas tight, quick as the 9500 series ported.. they have excellect dampening over the MMS.. the very reason the sound terrible sealed, and in small boxes.. the do suffer from gd, but its not huge as you would think..
low q low fs drivers are peaky ported.. thats why you see higher q higher fs designs do great ported..
t

[Jimi77]

Originally Posted by bassfreak 3) Ported enclosures work great for hip-hop, rap, pop, techno and other types of music with "artificial" bass. In other words "boom" sounds like "boom" even if the system is peaky. OTOH for a classic music listener or somebody who listens to traditional jazz music, the peak colors the sound of bass instruments, bass guitars in particular. Heavy metal with fast electric bass often turns to mud with ported enclosures. you failed to properly design a ported box or your using the wrong woofer. many many times ive hear ported alignments sound more transiant than sealed.. 9 outta 10 your hearing the muddyness from the lack of mechanical dampening.. to this day very few subs id or sealed sound aas tight, quick as the 9500 series ported.. they have excellect dampening over the MMS.. the very reason the sound terrible sealed, and in small boxes.. the do suffer from gd, but its not huge as you would think.. low q low fs drivers are peaky ported.. thats why you see higher q higher fs designs do great ported.. t

No I wasn't using the wrong sub, nor was the enclosure improperly designed. Your typical ported sub enclosure in the car audio world is tuned ~35hz and exhibits a peak from ~30-50hz (very broad generalization).

[Lycan Audio]

Originally Posted by bassfreak Consider the 9500 series ported.. they have excellect dampening over the MMS.. the very reason the sound terrible sealed, and in small boxes.. the do suffer from gd, but its not huge as you would think.. low q low fs drivers are peaky ported.. thats why you see higher q higher fs designs do great ported.. t

Now this is an interesting observation of the relationship between the weight of the driver's moving parts (MMS) and control of the suspension over them.

I say this because the EBP for the MTX 9500 (using the 12" Thunder 9512 in this example) is 49. If we thought no further, we'd assume that this subwoofer is best suited in a sealed box. However, a quick FR graphing shows the contrary.

So what's happening here? MMS is a weighty 286 grams and yet Qts is a nice middle of the road .57 (Qms 3 and Qes .7 sort playing a balancing act here)

What is it about this relationship that makes the 9500 lend itself so well to a ported enclosure despite EBP?

[bassfreak]

Originally Posted by Lycan Audio Now this is an interesting observation of the relationship between the weight of the driver's moving parts (MMS) and control of the suspension over them. I say this because the EBP for the MTX 9500 (using the 12" Thunder 9512 in this example) is 49. If we thought no further, we'd assume that this subwoofer is best suited in a sealed box. However, a quick FR graphing shows the contrary. So what's happening here? MMS is a weighty 286 grams and yet Qts is a nice middle of the road .57 (Qms 3 and Qes .7 sort playing a balancing act here) What is it about this relationship that makes the 9500 lend itself so well to a ported enclosure despite EBP?

sorry for the confusion and terrible typing..
DDs 9500..
mms is 250, vas is 85 liters, qms is around 3..
like alot of spl woofers it is overdamped, but its just designed for the larger slightly higher tunings.. its meant to be efficent as possible.. you sacrfice efficency for low frequency extention..
www.ddaudio.com

[bassfreak]

now model up the ascendant audio havoc..
http://ascendantaudio.com/havoc.php
note the mms, fs and qes..
the mms is 280g, but the vas is still 95 liters. the qes is .5 which means its still plenty strong but not overdamped so you don't get huge spikes around tuning..
despite it higher mms its fs of 29 shows mechanical damping is adquate for a small to medium low tuned box..
if i had to reccommend a sq alignment for this woofer id say 3.6 tuned to 30... i haven't modeled a woofer up in a while,but i don't really need too..