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Old 2nd July 2010, 06:33 PM   #11
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As a thought, 4x http://eminence.com/pdf/lab-15.pdf (per side?) might do it. 22mm p/p Xmax on each would be enough for some real noise. Xlim is double that.
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Old 4th July 2010, 09:10 AM   #12
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The grey curve looks good. Remember, the room is going to change the response more than anything else, and you'll get a rise on the low end from room gain. Make sure your port velocity is less than 17 m/s (the lower the better) at maximum power at any frequency, and be sure to flare both ends. Follow standard design guidelines. Some stuffing uniformly distributed throughout the box (but not allowed to get into the coil gap) will be beneficial.

EDIT: Haven't run your numbers myself but some of those curves look like they might have audible group delay.
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Old 4th July 2010, 05:50 PM   #13
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I'm going to have to clarify my statement about stainless steel for these spikes. Stainless steel is usually fairly soft, so if you want to use stainless steel you need to specify an alloy like 440C, HARDENED. But if this is going on a wooden floor (God forbid), it doesn't matter.
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Old 7th July 2010, 05:33 AM   #14
N4CR is offline N4CR  New Zealand
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Originally Posted by 454Casull View Post
EDIT: Haven't run your numbers myself but some of those curves look like they might have audible group delay.
What constitutes audible to you? I've heard some say sub bass group delay is not really audible but I highly doubt this (and scientific papers confirm this), it's probably one of the things sound characterisitics that put me off ported setups usually.

Anyway been working on these last two to three nights till very late am so let me know what you guys think.
Sealed is probably the way to go @ qtc .707 .418m3 however PR seems to have some impressive and relatively clean numbers with added cost of twice the box size and 300+ usd cost.
Still thinking about amps, I have a feeling that's going to be the hardest decision as I'm trying to avoid going cheap pro amp..

Transfer function phase is pretty much identical 150-20hz

And lastly I must thank everyone on this thread and forum for the little tidbits of info which have helped me greatly in my quest for ultimate bass
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Old 7th July 2010, 06:22 PM   #15
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What constitutes audible to you? I've heard some say sub bass group delay is not really audible but I highly doubt this (and scientific papers confirm this), it's probably one of the things sound characterisitics that put me off ported setups usually.
Group delay audibility is relative to frequency, with greater delay more tolerable as frequency goes down. I don't think there are any hard numbers to go by, but if there are any sharp spikes in group delay in the passband it could be audible.
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Old 9th July 2010, 12:25 AM   #16
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I have stumbled upon a set of curves i'd forgotten a long time ago.. the 'equal loudness curves' http://upload.wikimedia.org/wikipedi...indos1.svg.png which reckon for 100 phon reference in mid to low range its pretty flat till 100hz which it gradually increases till when you need about 128-130 db @ 20hz to keep up, vastly more db required than at 300hz.... so as far as I understand and hear on mine and other rigs.... once you approach under 30-40hz it appears to drop off even though everything is rattling, to compensate you need a metric crap-tonne of spl to get a percieved flat response.
Did Reubens have astigmatism? Why did he draw long people?

To make a long story short, you set your bass levels by ear. There is no defensible engineering solution. This will come as a surprise to many.

Tube amp, eh. I just sold a Partridge output transformer on eBay for $900. Gosh it looked good.
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Old 9th July 2010, 09:26 PM   #17
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Originally Posted by N4CR View Post
I have stumbled upon a set of curves i'd forgotten a long time ago.. the 'equal loudness curves' http://upload.wikimedia.org/wikipedi...indos1.svg.png which reckon for 100 phon reference in mid to low range its pretty flat till 100hz which it gradually increases till when you need about 128-130 db @ 20hz to keep up, vastly more db required than at 300hz.... so as far as I understand and hear on mine and other rigs.... once you approach under 30-40hz it appears to drop off even though everything is rattling, to compensate you need a metric crap-tonne of spl to get a percieved flat response. So if I rigidly stick with a flat response on paper I get a percieved dropoff in sound volume even though it's 'flat', which sure as hell isn't what I'm looking for, I want it to sound flat to me, not a graph. I'm guessing this is one of the reasons why the sub has been designed with a 16hz fs.
ANyone have any comments or feedback on especially the equal loudness curve and has anyone else designed around it. I understand it is an average and may be different to me but it's a good start for now.
Dunno how I missed this, but you need to ignore the equal loudness curves completely and just aim for a decently flat response. All that crap was dealt with by the artist or musician (e.g. the pianist, not the audience, determines the relative loudness between his low-pitched notes and high-pitched notes), you don't need to fool around with it on your speaker.

EDIT: I mean, if you really want your bass to overpower everything you could do that, but it just sounds WRONG. It would be like setting your tone controls to 11.
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Old 9th July 2010, 09:55 PM   #18
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Dunno how I missed this, but you need to ignore the equal loudness curves completely and just aim for a decently flat response. All that crap was dealt with by the artist or musician (e.g. the pianist, not the audience, determines the relative loudness between his low-pitched notes and high-pitched notes), you don't need to fool around with it on your speaker.

EDIT: I mean, if you really want your bass to overpower everything you could do that, but it just sounds WRONG. It would be like setting your tone controls to 11.
Oh my Gawd.... do you allow the artist into your living room and let him or her twiddle with your volume knob?
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Old 9th July 2010, 10:24 PM   #19
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Oh my Gawd.... do you allow the artist into your living room and let him or her twiddle with your volume knob?
Speak more directly, please.
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Old 9th July 2010, 10:29 PM   #20
badman is offline badman  United States
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Quote:
Originally Posted by 454Casull View Post
Dunno how I missed this, but you need to ignore the equal loudness curves completely and just aim for a decently flat response. All that crap was dealt with by the artist or musician (e.g. the pianist, not the audience, determines the relative loudness between his low-pitched notes and high-pitched notes), you don't need to fool around with it on your speaker.

EDIT: I mean, if you really want your bass to overpower everything you could do that, but it just sounds WRONG. It would be like setting your tone controls to 11.
Um, not really. Most mastering is done louder than a typical home listening session. Unless you match listening level to recording level, you must boost the treble and bass to get perceptively equal tonal balance.
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