wall question for pros

[Team TH (Donny) 10+ year member]

What you have been told or how you are interpreting this "advice" is wrong.
You are saying a 4th order bandpass is good because it will reach your ears but a normal 4th order will scatter everywhere and go out the windows?

You need to do some more research on what you want and how you are going to get there.

When you have a port forward firing in a wall, it's always best to have it, if optimal, on one side of the vehicle.

Preferrably driver side.

Your higher score will usually come from passenger side.

If it's swapped, typical interference from the steering wheel can cause score to go down.

Not all vehicles do that though but most do.

It is typical the pressure will increase when the window\door that is on same side as port is open.

IF pressure decreases when you do this, then you have displaced more volume in the vehicle than what is forward the B pillar.

This is the actual goal when building a wall but not all walls will be able to do this based on goals.

This is also why many vehicles into the 170s and higher need to be sealed to continue gaining pressure.

This is correct from my experience in competing.

 

[TnT_Sounds 10+ year member]

I believe that it was read wrong. I was comparing a normal 4th order vs a vented all subs and port firing forward.

From speaking with mike singer I got the info I was looking for. Surprisingly no computerized program that he knows of will map/plot a 4th order for the vehicle dependent. Their is a certain ratio to stay within per the subs ebp and with slight port tuning and sealed box size I could obtain the sound I am wanting. He also said when doing a bandpass for musical purposes it is key the port remains unobstructed by seats and center consoles as the cabin is going to need to act as another enclosure. So the port is ideally to be located in the center.

I think I got the info I was after though so this thread proved helpful.

Thanks for everyone's insight.

 

[Moble Enclosurs 10+ year member]

I believe that it was read wrong. I was comparing a normal 4th order vs a vented all subs and port firing forward.
From speaking with mike singer I got the info I was looking for. Surprisingly no computerized program that he knows of will map/plot a 4th order for the vehicle dependent. Their is a certain ratio to stay within per the subs ebp and with slight port tuning and sealed box size I could obtain the sound I am wanting. He also said when doing a bandpass for musical purposes it is key the port remains unobstructed by seats and center consoles asthe cabin is going to need to act as another enclosure. ...So the port is ideally to be located in the center.

I think I got the info I was after though so this thread proved helpful.

Thanks for everyone's insight.

First bold:Correct, but it can be done. I consider it in my designs.

Second bold:this was mentioned in post number 5, so it is good that he reminded this importance.

Third bold: makes a difference. Most of the high LF dips in the vehicle response will be near the center of the vehicle for the listening position. When loading near the center, it changes the response to accomidate this effect. Great for output.

Just wanted to add these things real quick.

 

[Team TH (Donny) 10+ year member]

Ok, 4th order is much better in many aspects.. HOWEVER, you must built it in respect to your desires. You must also have a great understanding about how to design a 4th order not just knowing the "basics" before you seek to build it. A ported enclosure would be easier to design than the 4th order, but the 4th order is much easier to design than say a 6th or especially an 8th order.

 

[TnT_Sounds 10+ year member]

First bold:Correct, but it can be done. I consider it in my designs. Second bold:this was mentioned in post number 5, so it is good that he reminded this importance.

Third bold: makes a difference. Most of the high LF dips in the vehicle response will be near the center of the vehicle for the listening position. When loading near the center, it changes the response to accomidate this effect. Great for output.

Just wanted to add these things real quick.

Great info thank you again man! i'm still trying to learn more as I go before I start on this.

Ok, 4th order is much better in many aspects.. HOWEVER, you must built it in respect to your desires. You must also have a great understanding about how to design a 4th order not just knowing the "basics" before you seek to build it. A ported enclosure would be easier to design than the 4th order, but the 4th order is much easier to design than say a 6th or especially an 8th order.

I was told winisd can plot 4th orders within 2db accuracy and response curves with accurate TSP's. I have klippel accurate specs for my subs and winisd is showing a very "musical" range from 26hz - 62hz before any -3db when I plot them. I am no way claiming to know nearly enough however to be confident enough to build this. I am still second guessing my self. I have got the ratio bit almost down and am still playing with box dimensions that my subs will allow before any thermal or power loss.

 

[hispls 5,000+ posts]

My .02$ build a few 4th orders for a single sub and play with them a bit. Once you have a good feel for what works (ratios and tuning) scale it up X8. What you're talking about is VERY permanent and it would **** to get it wrong.

 

[TnT_Sounds 10+ year member]

My .02$ build a few 4th orders for a single sub and play with them a bit. Once you have a good feel for what works (ratios and tuning) scale it up X8. What you're talking about is VERY permanent and it would **** to get it wrong.

Very good idea! That is exactly what I'm afraid of... I'm famous for doing things wrong.

 

[TnT_Sounds 10+ year member]

another thing, when I start tweaking with one, if I am wanting more output how would I go about doing so? start with shrinking a side or change tuning etc... and what are the repercussions of doing the changes?

 

[Team TH (Donny) 10+ year member]

I was told winisd can plot 4th orders within 2db accuracy and response curves with accurate TSP's. I have klippel accurate specs for my subs and winisd is showing a very "musical" range from 26hz - 62hz before any -3db when I plot them. I am no way claiming to know nearly enough however to be confident enough to build this. I am still second guessing my self. I have got the ratio bit almost down and am still playing with box dimensions that my subs will allow before any thermal or power loss.

Take what info you have now and do as hispls talked about. Build a 4th for a single first. You can test and tweet stuff with a single much easier than thinking you have everything all good to go for all 8, because most likely you wont get it the best on first try.

 

[TnT_Sounds 10+ year member]

another random question.. I have heard some talk from bandpass builders and they are saying something about a loading wall..

I thought bandpasses had internal loading walls?

The ratio thing is kind of confusing me now. I really dont know to much about the figures. How does one depict what side of the ratio is to be used for the box? For example a 2:1 ratio; which side is sealed and which is vented? I was told to stay within .8-1.2 for each sub in a common chamber.

Then how do i figure the ratios? Say a 1.5:1 ratio?