low EBP and 4th order bandpass boxes

[Beatin' 10+ year member]

Why are low EBP subs that are best put in sealed boxes also are recommended for bandpass boxes?

Graphing out these subs in winisd shows ATROCIOUS group delay characteristics. I don't understand how such subs could be recommended to be put in a 4th order bandpass, A KNOWN HELMHOLTZ RESONATOR. wtf is going on?

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[hispls 5,000+ posts]

Model some high EBP subs and report back on how they look.

 

[Beatin' 10+ year member]

Model some high EBP subs and report back on how they look.

I have modeled such subs and tuning around Fc shows decent results if you account for cabin gain to help further increase low end response.

The group delay is far better with high EBP subs. Typically exhibiting one hump rarely exceeding 10ms with a smooth low frequency roll off.

 

[hispls 5,000+ posts]

Well, you got me there if you can make them model nicely.

 

[dbjunior 10+ year member]

If you looking at group delay you might be more concerned with sq. Most people around here just want loud.

 

[SounDrive Pro Seller]

Now, try this and see if the modeling and real world results line up. I'm genuinely curious.

 

[Beatin' 10+ year member]

If you looking at group delay you might be more concerned with sq. Most people around here just want loud.

I like loud too. However, what's the point of having "loud" if the roll off of a kick drum plays like crap because the beginning and end of the signal want to play out of the port at the same time due to group delay timing differences?

one-note bass lines and synthesized percussion is fine with high group delay but when a signal goes through multiple frequencies in a split second, high group delay is a major problem. This is where I see high EBP subs having an advantage.

Some of these low EBP subs need such HUGE boxes for one 15". And still they have two huge group delay peaks above 20ms and a trough around 10-15ms. Outside of the group delay peaks within 10hz the group delay drops to below 10ms. Looks like a disaster.

 

[dbjunior 10+ year member]

When I look for 4th friendly I just look at QTS over .5 the lower the fs the better preferably in the 20's and a as much throw as possible such as zv4 or obsidian 18's. My only concerns with it are loud and low like a 4to1 ported to sealed tuned at 45hz. I've honestly never looked much at group delay but I also don't demo very much real music, mostly rap and synthetic bass material.

 

[Notloud00 10+ year member]

Now, try this and see if the modeling and real world results line up. I'm genuinely curious.

This, playing it in a car vs the computer are much different. Way to many variables in real life.

 

[Beatin' 10+ year member]

When I look for 4th friendly I just look at QTS over .5 the lower the fs the better preferably in the 20's and a as much throw as possible such as zv4 or obsidian 18's. My only concerns with it are loud and low like a 4to1 ported to sealed tuned at 45hz. I've honestly never looked much at group delay but I also don't demo very much real music, mostly rap and synthetic bass material.

From what I understand, those subs with the high Q and low Fs and EBP don't play too well above 50hz. Their Fc in a sealed box is so low that trying to get more output in the 50-100hz range without horrible group delay is impossible. With subs that have higher EBP, Fs, and lower Q, bandpass allows for moderate to low group delay and have increased output like a bandpass box is supposed to provide in the most important frequency range, 30-80hz.

And I know things are different in a car, but I'm focusing on anechoic performance for now.

 

[hispls 5,000+ posts]

From what I understand' date=' those subs with the high Q and low Fs and EBP don't play too well above 50hz. Their Fc in a sealed box is so low that trying to get more output in the 50-100hz range without horrible group delay is impossible. With subs that have higher EBP, Fs, and lower Q, bandpass allows for moderate to low group delay and have increased output like a bandpass box is supposed to provide in the most important frequency range, 30-80hz.
And I know things are different in a car, but I'm focusing on anechoic performance for now.[/quote']

I find that modeling software is quite good to predict actual response (provided you understand your car's peaks and nulls). Nothing for it but for you to get some wood and start making boxes. I got over bandpass alignment in the mid 90's. I'm quite confident that if they were magical free output with no downside they would be widely used by people who actually care about sound quality and accurate reproduction of the source.

 

[Beatin' 10+ year member]

I find that modeling software is quite good to predict actual response (provided you understand your car's peaks and nulls). Nothing for it but for you to get some wood and start making boxes. I got over bandpass alignment in the mid 90's. I'm quite confident that if they were magical free output with no downside they would be widely used by people who actually care about sound quality and accurate reproduction of the source.

It's not that i want SQ bandpass. It's the idea of a bandpass getting loud with acceptable SQ that interests me. Higher than usual EBP seems to provide that.

 

[hispls 5,000+ posts]

It's not that i want SQ bandpass. It's the idea of a bandpass getting loud with acceptable SQ that interests me. Higher than usual EBP seems to provide that.

Start making some sawdust then. Nothing to it but to do it. IMO not worth the effort unless you're shooting for a one-note-wonder, and even then expect it to cost a lot in materials and time before you get the results you're after.