6th Order Blow Through Question

[ThxOne Premium Member]

@Buck
If I had a truck and wanted to do a 6th order blow through with 4 - 12" subs would it be smarter to have the ports from the enclosures right where the port for the blow through would be? I have seen a couple of 6th order blow through designs for a truck and every one has the ports coming together at the rear of the main chamber (all designs have two subs facing each other [two subs per side])?

To me it seems that you would get more out of it having all the ports coming together where the bass enters the cab of the truck. Thoughts?

An example of what I keep seeing is this...

Click to read more...

 

[Buck 5,000+ posts]

@Buck
If I had a truck and wanted to do a 6th order blow through with 4 - 12" subs would it be smarter to have the ports from the enclosures right where the port for the blow through would be? I have seen a couple of 6th order blow through designs for a truck and every one has the ports coming together at the rear of the main chamber (all designs have two subs facing each other [two subs per side])?

To me it seems that you would get more out of it having all the ports coming together where the bass enters the cab of the truck. Thoughts?

An example of what I keep seeing is this...

If you mean where to place the rear port, I would tend to put the port as far back in the box as far as possible, that way the whole front chamber is properly pressurized and the rear port air meets proper impedance or restriction from the front port. The flow of the waves through the box matters, at least somewhat, to a degree. So for a series 6th you want to make sure the rear port air properly pressurizes the entire front chamber. That's how I do it, at least.

Here's an example:



^^^that design wasn't built but that's the best type of lauout IMO. Or this:



Follow the waves from the rear cone or cone in rear chamber all the way out of the front port, it's a straight line sort of, as in the rear cone energy is forced to move through all the airspace of the box, both chambers and ports. That box did very well^^^

So just remember the rear port relies on the front port for tuning to achieve proper rear tuning. If your rear port is like right next to your front port and there's a front huge chamber where the rear port air can largely or somewhat bypass, there might be some negative consequences to that. I realize sometimes layout is difficult with series 6th's.

So here's a series 6th I did for an underseat pickup which is really funky to do, so the rear port would up being fairly close to the front port:



That's why the rear port in the front chamber turns like it does to try to help it pressurize the front chamber better, since the rear port is so far into the front chamber and close to the front port. That layout just had to be that way to make it work, and I was told it worked well and sounded good. 2 6.5 DC subs, series 6th.

 

[ThxOne Premium Member]

That all makes sense and then I see the JL HO enclosures... where the port meets in front of the woofer in the "coupling chamber" and it makes me think "what if there was a coupling chamber in the 6th order blow through?" You follow?

 

[Buck 5,000+ posts]

That all makes sense and then I see the JL HO enclosures... where the port meets in front of the woofer in the "coupling chamber" and it makes me think "what if there was a coupling chamber in the 6th order blow through?" You follow?

View attachment 67983

That's what the front chamber is. Basically the front chamber is just a resonance chamber you're adding inside of the rear port, with a series 6th. It's just a chamber to store energy at a different (higher) frequency that's in line with the port, as in the front port is actually just all a rear port where you tap or add in a chamber that can be charged with higher frequencies, so you can like double-pressurize. That JL box, you could like put a plate on that face and make an Aeroport front port or something and that would be a series 6th. I mean it's very close to a series 6th the way it is.

 

[ThxOne Premium Member]

That's what the front chamber is. Basically the front chamber is just a resonance chamber you're adding inside of the rear port, with a series 6th. It's just a chamber to store energy at a different (higher) frequency that's in line with the port, as in the front port is actually just all a rear port where you tap or add in a chamber that can be charged with higher frequencies, so you can like double-pressurize. That JL box, you could like put a plate on that face and make an Aeroport front port or something and that would be a series 6th. I mean it's very close to a series 6th the way it is.

Very interesting indeed. I have been looking at single cab pickups and I have always wanted to do 4 - 12's ported into the cab since the mid 1990's. Today's subs are far more violent then the subs back then. I think it could be really fun.

 

[Buck 5,000+ posts]

Very interesting indeed. I have been looking at single cab pickups and I have always wanted to do 4 - 12's ported into the cab since the mid 1990's. Today's subs are far more violent then the subs back then. I think it could be really fun.

I really like series 6th's.

Like with the coupling chamber thing, this is basically a series 6th but where the sub radiates into the cab instead of into the "front" chamber. So like it's the same math pretty much, but my point is you can disappear the front chamber and it's just a ported box, so the front chamber is sort of like an add-on resonance chamber that is part of the rear port. This was built and I was told worked well:



It's basically the same thing with a series 6th, front chamber is actually part of the rear port, you can sort of think of it like that, so you want to make sure the whole port-system pressurizes properly in regards to port placement, optimally. And yeah today's subs in a series 6th would be stupid fun.

 

[chillin 10+ year member]

If you mean where to place the rear port, I would tend to put the port as far back in the box as far as possible, that way the whole front chamber is properly pressurized and the rear port air meets proper impedance or restriction from the front port. The flow of the waves through the box matters, at least somewhat, to a degree. So for a series 6th you want to make sure the rear port air properly pressurizes the entire front chamber. That's how I do it, at least.

Here's an example:



^^^that design wasn't built but that's the best type of lauout IMO. Or this:



Follow the waves from the rear cone or cone in rear chamber all the way out of the front port, it's a straight line sort of, as in the rear cone energy is forced to move through all the airspace of the box, both chambers and ports. That box did very well^^^

So just remember the rear port relies on the front port for tuning to achieve proper rear tuning. If your rear port is like right next to your front port and there's a front huge chamber where the rear port air can largely or somewhat bypass, there might be some negative consequences to that. I realize sometimes layout is difficult with series 6th's.

So here's a series 6th I did for an underseat pickup which is really funky to do, so the rear port would up being fairly close to the front port:



That's why the rear port in the front chamber turns like it does to try to help it pressurize the front chamber better, since the rear port is so far into the front chamber and close to the front port. That layout just had to be that way to make it work, and I was told it worked well and sounded good. 2 6.5 DC subs, series 6th.

How was the output on that? I'd like to put something like that in the back of my ram pickup. The stock 8" Alpine doesn't really cut it and I have two huskies that use the back seat area a lot, so having the speakers in the box would offer good protection.

 

[ThxOne Premium Member]

I really like series 6th's.

Like with the coupling chamber thing, this is basically a series 6th but where the sub radiates into the cab instead of into the "front" chamber. So like it's the same math pretty much, but my point is you can disappear the front chamber and it's just a ported box, so the front chamber is sort of like an add-on resonance chamber that is part of the rear port. This was built and I was told worked well:



It's basically the same thing with a series 6th, front chamber is actually part of the rear port, you can sort of think of it like that, so you want to make sure the whole port-system pressurizes properly in regards to port placement, optimally. And yeah today's subs in a series 6th would be stupid fun.

So then say if I was making a blow through into a cab... is a small or large port better? I have seen somewhat small square ports into the cab, I have seen wide rectangles... Hell, I have seen 90° pipes come out of the top of the box in the bed and port through the back glass of the cab.

 

[Buck 5,000+ posts]

How was the output on that? I'd like to put something like that in the back of my ram pickup. The stock 8" Alpine doesn't really cut it and I have two huskies that use the back seat area a lot, so having the speakers in the box would offer good protection.

I'm really not sure, I don't get to hear most of what I design, I rely on their feedback. Both that were built sounded good, or so I was told. The bigger one for the 2 sundown 12's was tuned to like 22 hz and 44 hz or so for specific competition type thing. That box is nuts that one was fun. The DC one I was told sounded good, I mean 6.5's are just limited themselves somewhat with bass response but it seems to work like a proper 6th would. To give an example I've done some smaller series 6ths for like single 12's at like 1500w and they can get a play range of like 27 hz to like 70-75 hz strongly. A ton of factors to that but for heavy bass I think the range is acceptable for many. They're just big boxes, comes at a cost.

 

[Buck 5,000+ posts]

So then say if I was making a blow through into a cab... is a small or large port better? I have seen somewhat small square ports into the cab, I have seen wide rectangles... Hell, I have seen 90° pipes come out of the top of the box in the bed and port through the back glass of the cab.

That just depends on the subs and power. The front port can really vary, I mean like you can have a front port that's only 16 square inches per cube or some that it's well north of 30 square inches per cube. Like if you put 4 4500w 12's in your bed, you know you'll need a honker of a front port lol.

 

[ThxOne Premium Member]

That just depends on the subs and power. The front port can really vary, I mean like you can have a front port that's only 16 square inches per cube or some that it's well north of 30 square inches per cube. Like if you put 4 4500w 12's in your bed, you know you'll need a honker of a front port lol.

Ok so it does matter and there is probably a standard I am guessing for specific enclosure volume and tuning?

 

[Buck 5,000+ posts]

Ok so it does matter and there is probably a standard I am guessing for specific enclosure volume and tuning?

It would be the same as ported basically for rear. The rear is what basically matters, as it's the foundation. So say a 12 wants 2 cubes ported - that's what you'd give the rear airspace typically in series 6th for proper cone control/chamber loading. Tuning can be whatever just based on how high-low you want to play, like regular ported. The front port can be wildly different. You basically don't even really have to have a front chamber much if you don't want to, or you can have a massive one. Using a 12 with 2 cubes, you could have a front chamber that's only 1 cube, or you can have a front chamber thats 4 cubes or like even different than that. There's sort of an art to knowing how you want that to be and knowing what the changes do.

Rear tuning would basically be whatever you'd want in a ported box. Front tuning would typically be octave above rear tuning, so say like 32/64 hz rear/front. But unlike parallel 6th's, you won't get cancellation because a series 6th is in series, so you can actually tune the front chamber way lower for more Spl, but musically that would ****. I tend to do the octave split or close to that for most boxes, and I tend to have a front chamber that's about 1.5x bigger than rear, but there's many options, that's what makes them so fun.

 

[Buck 5,000+ posts]

Rear port area is also something that is an art and can vary quite a bit, because you don't get port noise in a series 6th like a ported box, because the front chamber basically dampens and slows the air down coming out of the rear vs the rear port air dumping directly into the cabin at super high velocity. So you can do things like do a very small rear port in some cases and not get port noise, which can be used to your advantage.

 

[ThxOne Premium Member]

Rear port area is also something that is an art and can vary quite a bit, because you don't get port noise in a series 6th like a ported box, because the front chamber basically dampens and slows the air down vs the rear port air dumping directly into the cabin at super high velocity. So you can do things like do a very small rear port in some cases and not get port noise, which can be used to your advantage.

So if the 2-12 enclosures are on each side facing a center chamber and lets say for simplicity that each ported enclosure is 4cu. ft.. By what you are saying the center chamber should be near 6.5cu.ft.?

 

[Buck 5,000+ posts]

So if the 2-12 enclosures are on each side facing a center chamber and lets say for simplicity that each ported enclosure is 4cu. ft.. By what you are saying the center chamber should be near 6.5cu.ft.?

It could be, just as long as you do it correctly. 4*1.5=6. If you have 4 12's that'd be 8 cubes rear so you'd need 12 by that math total in center (front) chamber , but the front can really vary, you just have to do it right. I'm just giving that ratio out in general, it doesn't have to be any way, just with all things considered, I find about that ratio to be where a good bit of my boxes fall, just roughly.

So you could say every 1 cube rear you maybe could aim at x1.5 ratio for front if you're getting started for first time. Just beware of how the front port adds to/lowers the rear port when it comes to the overall tuning of the rear chamber, that's the hardest part to figure IMO.