IB sub and time/speed question

[Darren]

Hi Guys,

There is a topic on the shack where people are arguing the speed or responsiveness of several types of subs including IB. I'm not that knowledgeable on that end of things so I thought I'd bring a few of the questions from one member to this forum. I'm very interested in the answers as well and would love to add some facts to the conversation.

The questions are below:

<snip>
There may be advantages to using huge boxes or tubes, or IB, but I've seen nothing to prove that this ringing is eliminated.


1. Is IB or EBS system well damped in the mid bass, and not so well at very low bass or "system resonance?"

2. If the ringing is limited to the very low bass, will there still be slop generated from signals in the musical range?

3. Where is the measured data on this?

</snip>

The thread: www.hometheatershack.com/forums/diy-speakers-subwoofers/1410-ib-ebs-time-domain-performance.html#post10209

[ThomasW]

People interested in these types of questions are encouraged to build a
variety of subs. Then they should listen to the differences in those subs, and measure any parameters they consider important...

[Darren]

He he, I agree... I've listened to two of them and let them know that the IB integrates much better than my PR'd box sub. I couldn't give them hard facts, only my observations.

[ayreonaut]

Hi, it's me, the Original Poster.

Darren, I came over here to do the same thing, and see you've beaten me to it!

ThomasW, you're absolutely right that the only way for an individual to know for sure which type he prefers is to hear them all in his room. (I'm planning to give IB a shot before the end of the year.)

Still, Ilkka has posted tons of his measurements on sealed and ported subs, and they make for very interesting viewing and discussion. I also get sick of the long arguments on a certain site where pure opinion and conjecture abound. I'm of the opinion that time domain performance is of the utmost importance, yet I rarely see this measured. (Ilkka did, way to go Ilkka.) Some hard data on IB and EBS time domain performance would certainly shed some light, maybe put this issue to bed, and settle my own mind.

Unfortuantely, I have no idea how to do these measurements myself. I sent an e-mail to Ilkka asking if he might do it, and I'm awating his reply.

[ThomasW]

If you want to make these kinds of measurements you need a mic, mic-preamp, PC with a duplex sound card and appropriate software. ETF or a similar energy time gated measurement program is the necessary software.

To test the impulse response of an IB one doesn't need to build an IB. All one needs to do is mount the driver of choice in a simple flat baffle.

[crackyflipside]

admin said:

To test the impulse response of an IB one doesn't need to build an IB. All one needs to do is mount the driver of choice in a simple flat baffle.

But then how do you remove the rear wave from being measured???

[ThomasW]

crackyflipside said:

But then how do you remove the rear wave from being measured???

We're comparing alignments not the effects of the room. Impulse responses are measured nearfield and they're time gated. There is no rearwave in that situation.