For those who have listened to IB subs.... - Page 15 - AVS Forum
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post #421 of 428 Old 06-25-2010, 06:21 AM
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Originally Posted by ChrisBee View Post

Are we knee deep in satisfactory working examples of your idol's suggestions? Or do they remain impractical theoretical models of interest only to the disciples of your revered audio prophets?



Well, if you want a superior response in room then yes, you will need to read a few books that Toole has produce. For all your banter, why do you not post your in room reponse of your so called incredible sub setup?? Heck, what mains are you using again?


I guess pointing out that multiple sealed designs around your room would have created a better response but lets not worry about audio science when you have clearly superior ears

Instead lets post silly audiophile thoughts like "faster bass" or how about these PHONY statements "rich in delicious harmonics" or "hear the rich detail in the bass"

Pathetic audiophile commentary that has NO PLACE in DIY!!

In DIY measurements matters, you do not have good ones...your setup shows you lack the basic concepts found in audio science. Come back when you get a little more education.

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post #422 of 428 Old 06-25-2010, 06:31 AM
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Quote:
Originally Posted by ChrisBee View Post

If that were true, and since most system use just such a filter,

And so transient response with a decent, non pathologically bad system is a moot point. Maybe read up on Fourier.
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Originally Posted by ChrisBee View Post

all subwoofers would sound identical.

It is only one aspect of system design and implementation that I commented on and I did not make the statement you did.
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post #423 of 428 Old 06-25-2010, 07:07 AM
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Quote:
Originally Posted by ChrisBee View Post

If that were true, and since most system use just such a filter, all subwoofers would sound identical.

Though I have noticed that lowering the crossover point robs the system of life and attack. This, despite having 38Hz(-3dB) mains. Measured and confirmed with REW...

I should hope your IB does better at 80hz than your mains with 4x4" drivers... Sure they're "flat to 38Hz measured" but how much boost is built into the XO to achieve this!? 80hz may even be pushing it, I found that with my old mains (2x6.5" drivers = 33% more cone area than 4x4" drivers) crossing at 120hz gave me the cleanest midbass... although my IB manifold is front and center so crossing that high was an option, I'm not sure where yours is located?

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Originally Posted by ChrisBee View Post

Let's think about this for one moment: Multiple, discrete subwoofers cannot be spaced equidistantly from the listener and relative to the room boundaries if the listener is to avoid the usual null point in the centre of the room. In fact it is difficult to imagine a situation where the time domain is not seriously violated. EQ will not help the situation except in the crudest sense regarding FR. Reflections from the non-equidistant boundaries will only compound the mischief.

Are we knee deep in satisfactory working examples of your idol's suggestions? Or do they remain impractical theoretical models of interest only to the disciples of your revered audio prophets?

lol... So, you built a sub and now you presume that you know more than the guys that have devoted their lives to audio theory!? I am also very happy with my IB but I'm not pretentious enough to think that qualifies me to act like I know everything about subwoofers After all, aren't you just "A bumbling, amateur speaker builder"
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post #424 of 428 Old 06-25-2010, 07:49 AM
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Originally Posted by A9X-308 View Post

Transient response / slew rate is a high frequency function and will be determined in a sub, mainly by the LPF employed. Given systems of reasonable capacity and design (and no pathological faults), and both using an (arbitrarily selected for discussion) 80hz LR24 it will be predominantly the filter that determines system response.

This is spot on correct. It's a pleasure to read actual fact once in a while.

Directly related is the simple fact that a sub with better transient response allows for selection of a higher crossover point with no FR or distortion penalty.

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post #425 of 428 Old 06-25-2010, 01:10 PM
 
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post #426 of 428 Old 06-25-2010, 03:08 PM
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Originally Posted by goneten View Post

Are there any studies available that show that thermal compression can contribute to 'slower bass, slower attack, loss of life etc' ?

I don't know what the subjective terminology would be, but yes there are plenty of studies showing that thermal compression changes both the frequency response and the Q of the system. That is to say, it's not just a linear form of distortion that can be "fixed" by just cranking up the driver more as it gets hot (until it melts, at least).

The JBL Pro website has a few posted.

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post #427 of 428 Old 06-25-2010, 10:44 PM
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Originally Posted by steve71 View Post

I'm curious, what is your setup Soho54? Bass horns?

Sorry, I missed this.

Right now it is a little lacking after a unscheduled move, and limited funds. My previous setup was four 15"s in an IB on LFE, and two 15" 13Hz tuned sonos on the mains as a 4th way. The Mains are pulling LFE duties right now, and as it is I can play things ~10dB louder than I ever listen, so I am content.

Before that it was too many to list, and I have built even more for others. I have scouted out the area under my house where eight drivers would fit quite nicely, as I have no more room inside, and the only way to go is down.

I am not a fan of bass horns in my personal setup. Not enough extension, and the one that does have it is too deep. Now PA on the other hand...
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post #428 of 428 Old 06-26-2010, 12:01 AM
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Originally Posted by lennon_68 View Post


lol... So, you built a sub and now you presume that you know more than the guys that have devoted their lives to audio theory!? I am also very happy with my IB but I'm not pretentious enough to think that qualifies me to act like I know everything about subwoofers After all, aren't you just "A bumbling, amateur speaker builder"

Having one's self-deprecating humour thrown back in one's teeth is probably par for the course here.

It's not as if my subwoofer and speaker building as far back as the 60s (and both before and since) has any real validity in the eyes of the scientific, number crunchers here. Though it is odd to find so many suffer from ADHD in one place, isn't it? Perhaps you covet the title of absent minded professors?

Of course they weren't known as subwoofers back then. Nor did we have a choice of large, dirt cheap, low Fs, high excursion drivers. Nor the free design and test software and backup-team of "scientist" forum buddies to take all the worry out of our own ideas.

Nor did we have power and machine tools at our disposal. Amplifiers were candle-power valve affairs. Even the materials and finishes you take so much for granted were completely absent. Personal disposable income for hobbies, such as these, was strictly in the hands of the middle classes. The luxuries you now take completely for granted were not even in our wildest dreams. So, get over yourselves.
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