Ported Cab's or non Ported....

[Mr. Foxen]

[quote name='stevie' post='567248' date='Aug 12 2009, 08:02 PM']Lots of strongly held opinions here but not much evidence (make that no evidence). This is not the scientific way, guys. It isn't so just cos you say so.[/quote]

Bill almost never elabourates on why he's right, only on why someone else is wrong. I don't think it is in his business interests to do otherwise. When pressed, Claber will write a huge essay that takes several reads to understand. I prefer the latter approach.

[Bill Fitzmaurice]

[quote name='Mr. Foxen' post='567269' date='Aug 12 2009, 03:14 PM']Bill almost never elabourates on why he's right, only on why someone else is wrong. I don't think it is in his business interests to do otherwise. When pressed, Claber will write a huge essay that takes several reads to understand. I prefer the latter approach.[/quote]
If you want to look into this further there are many sources available. Try Dr. Earl Geddes for one. My personal philosophy regarding posts on forums is that anything worth saying is worth summarizing in a few concise paragraphs, if not a few concise sentences. If you want to be bored to tears read an AES Preprint. My job requires that I read every one when they appear, so I have to suffer through them. Your's doesn't.

Edited August 12, 2009 by Bill Fitzmaurice

[alexclaber]

One useful link: [url="http://www.trueaudio.com/post_010.htm"]http://www.trueaudio.com/post_010.htm[/url]

Alex

[alexclaber]

And another: [url="http://www.diyaudio.com/wiki/index.php?page=Group+Delay"]http://www.diyaudio.com/wiki/index.php?page=Group+Delay[/url]

Alex

[stevie]

Cheers, Alex. Those discussions don't actually come down on one side of the fence of the other. Last I heard, there had been no definitive study of the subject, although Bill is implying that he has seen a recent study that we're not privy to. He's just not prepared to share that information.

On a more practical level, and returning to the original subject, lower group delay is the single and only advantage that a sealed cabinet has in pro sound bass applications. Whether or not it is audible, reflex cabinets have so many benefits that sealed is hardly ever a sensible option for bass.

My own view is that the impression of 'fast' and 'slow' bass is due to a combination of factors including high frequency extension and delayed resonances, although other artefacts such as frequency response anomalies can also contribute.

[alexclaber]

[quote name='stevie' post='568152' date='Aug 13 2009, 04:42 PM']Cheers, Alex. Those discussions don't actually come down on one side of the fence of the other. Last I heard, there had been no definitive study of the subject, although Bill is implying that he has seen a recent study that we're not privy to. He's just not prepared to share that information.

On a more practical level, and returning to the original subject, lower group delay is the single and only advantage that a sealed cabinet has in pro sound bass applications. Whether or not it is audible, reflex cabinets have so many benefits that sealed is hardly ever a sensible option for bass.

My own view is that the impression of 'fast' and 'slow' bass is due to a combination of factors including high frequency extension and delayed resonances, although other artefacts such as frequency response anomalies can also contribute.[/quote]

I'd agree with all that (though I'd say that those discussions come down more on the 'reasonable amounts of group delay are insignificant' side of the fence).

For high-end hi-fi I think it's worth worrying more about group delay and in fact any causes of stored energy which is just another reason why Linkwitz's active open-baffle designs are worth investigating if you have a big house and lots of money - but with the demanding SPLs, huge dynamic range and big bottom that is expected from bass guitar cabs there's no doubt in my mind that ported cabs are the way to go.

I believe another contributor to 'slow' bass response is the performance of speakers when hit with huge low frequency transients, as when slapping through an amp with deep extended lows. Speakers with too little clean excursion and too extreme a change in behaviour beyond Xmax seem to end up sounding more woolly than punchy when trying to handle such an input.

Alex

[stevie]

[quote name='alexclaber' post='568181' date='Aug 13 2009, 05:17 PM']For high-end hi-fi I think it's worth worrying more about group delay and in fact any causes of stored energy which is just another reason why Linkwitz's active open-baffle designs are worth investigating if you have a big house and lots of money - but with the demanding SPLs, huge dynamic range and big bottom that is expected from bass guitar cabs there's no doubt in my mind that ported cabs are the way to go.[/quote]

Interesting you should mention the Linkwitz dipole because I half-built one once just to see what it sounded like. I've never heard such clear, detailed bass before or since. They don't need to be expensive either, because you can use a passive crossover, but you do need to give them plenty of room, which is why I didn't pursue it.

[quote name='alexclaber' post='568181' date='Aug 13 2009, 05:17 PM']I believe another contributor to 'slow' bass response is the performance of speakers when hit with huge low frequency transients, as when slapping through an amp with deep extended lows. Speakers with too little clean excursion and too extreme a change in behaviour beyond Xmax seem to end up sounding more woolly than punchy when trying to handle such an input.[/quote]

Yes, and a properly rated magnet to control the cone movement. I think the term 'fast' when applied to bass doesn't so much mean starting fast but stopping fast.

[alexclaber]

[quote name='stevie' post='568197' date='Aug 13 2009, 05:32 PM']Interesting you should mention the Linkwitz dipole because I half-built one once just to see what it sounded like. I've never heard such clear, detailed bass before or since. They don't need to be expensive either, because you can use a passive crossover, but you do need to give them plenty of room, which is why I didn't pursue it.[/quote]

I'm working on something like this for acoustic instruments which might be rather good. Way too big for hi-fi for my little house sadly.

[quote name='stevie' post='568197' date='Aug 13 2009, 05:32 PM']Yes, and a properly rated magnet to control the cone movement. I think the term 'fast' when applied to bass doesn't so much mean starting fast but stopping fast.[/quote]

Yep. But of course all the magnet in the world won't do anything to stop the cone if too much of the voice coil is out of the gap, at which point you're dependant on the suspension which means the Q goes all awry. I've actually never heard such a good slap sound as from my prototype t'Midget - big excursion ability but very high damping and restricted lows means the woofer is always running within its limits and the motor strength to cone mass ratio is very high indeed.

Alex

[escholl]

[quote name='alexclaber' post='568181' date='Aug 13 2009, 05:17 PM']with the demanding SPLs, huge dynamic range and big bottom that is expected from bass guitar cabs there's no doubt in my mind that ported cabs are the way to go.[/quote]

i don't think anyone would disagree with you there. i suppose i didn't really elaborate enough on what i meant earlier, and may have given the wrong impression -- i was only referring to frequencies below about 100 Hz, and delays of about 5-15ms. for the record, i don't think group delay is something to worry about when buying a bass cab -- nothing in audio or electronics can be summed up in one figure anyways (like how "fast" the bass response is), as we all (should) know its a combination of many factors.