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Need Help Designing a 4th order blowthrough


Bubohms

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Well I try to avoid giving out specific recommendations when it comes to bandpass boxes, there are so many variables that effect how the box is going to sound its impossible for me to tell you what exactly will work best, I can give you some guidelines though.

For rear chamber size with your current amp 4 cubes total is probably about as big as you can go. Unfortunately the HDS212 subs aren't really well suited for 4th order bandpass box usage, they will work but they are limited by their relatively low Xmax (13.25 mm) and high Fs (39 Hz). At 4 cubes you should be fine to 2400 watts. If you upgrade to the BC3500 down the road you will need to be careful. Frankly, I'd be really wary of putting 3500 watts to those subs in a bandpass box.

For front chamber tuning, 45 Hz is a reasonable starting point. Its a good bit below your sealed resonant frequency, which is less than ideal, but there isn't much we can do about it. I strongly suggest you make your port removable or otherwise adjustable so you can tweak the tuning once you have the box playing. How much cabin gain you get, how low you cross over to your mids, and how you like your music to sound will all change just what the best tuning frequency is going to be for you, you will have to experiment a little bit.

Rear chamber size could be anything between 4 and 10 cubes total. With it on the smaller end you will have better bandwidth, but making it bigger will get your more output around your tuning frequency. There isn't going to be a huge difference in output between different size front chambers. Going from 6 to 10 cubes is only going to get you another 2 db or so of output. If you aren't going to be competing for numbers with this system, its very unlikely you would be able to hear the different between 6 cubes and 10 cubes and I'd be inclined to save the materials and space, but that's for you to decide. If you make the front chamber on the large size, you can alway shrink it down later, you will just have to re-tune the port afterwards to keep the tuning the same.

For port area, based on the watts you want to run I'd shoot for 18-20 sq in of area per cube of front chamber. It better to have more port area that you need than to not have enough.

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

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Alright and i mean im open to different boxes like you said earlier a bunch of wrong info is being spread about bandpass boxes so i always thought (bandpass=more output) and if thats not the case im fine with just a normal sealed or ported box. Bandpass was just something i was interested in ever since my dad told me about Toby Guynn's bandpass.

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Ext Cab. Im wanting this to be a blowthrough.

Yeah, in that case, bandpass is pretty much your only option.

A 6th order bandpass MIGHT work well for your application as well. I'll crunch some numbers when I get home later tonight and report back.

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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Ext Cab. Im wanting this to be a blowthrough.

Yeah, in that case, bandpass is pretty much your only option.

A 6th order bandpass MIGHT work well for your application as well. I'll crunch some numbers when I get home later tonight and report back.

Clamshell could work well.

Owner of BigAss Ports

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Ext Cab. Im wanting this to be a blowthrough.

Yeah, in that case, bandpass is pretty much your only option.

A 6th order bandpass MIGHT work well for your application as well. I'll crunch some numbers when I get home later tonight and report back.

Clamshell could work well.

Ext Cab. Im wanting this to be a blowthrough.

Yeah, in that case, bandpass is pretty much your only option.

A 6th order bandpass MIGHT work well for your application as well. I'll crunch some numbers when I get home later tonight and report back.

Thank you :good:

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Ext Cab. Im wanting this to be a blowthrough.

Yeah, in that case, bandpass is pretty much your only option.

A 6th order bandpass MIGHT work well for your application as well. I'll crunch some numbers when I get home later tonight and report back.

Clamshell could work well.

sorry but can someone explain a clamshell? heard the term before but dont know what it really is or how beneficial is it? a diagram or picture wood be great...

but yes op listen to these 3 guys they know there stuff... i would also look at cleansierra build log to get ideas its pretty dope... pretty much the same thing you want to do.

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Looks like a parallel-tuned 6th order would work pretty well. They aren't without their drawbacks though.

Compared to a 4th order bandpass box a parallel-tuned 6th order will get you wider bandwidth, more low frequency output, and smoother frequency response. All good things. The disadvantages though are its significantly more complex to design/build, will require a much bigger opening between your bed and your cabin, and will probably be an overall larger box.

Anyway, if it's something you are interested in I can post frequency response graphs showing the differences in output, cone excursion, etc.


"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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