How To Build A 6th Order Bandpass | Demo + Build Plans

As an avid audio enthusiast (Masters in Acoustical Engineering from Purdue), life long wood worker, and (as of last week) MECP Master certified car audio tech nerd, I have to say you do some of the cleanest and most professional builds I have ever seen. I have had the pleasure to have worked with an extremely wide variety of audio nerds. Your designs are well thought out, well explained, and very well executed. Thank you sharing your time and knowledge with us Youtubers.

Awesome way to show what bassheads need to know, thanks

That thing turned out great. Building one of those is one of my bucket list items. Thanks for the inspiration and the real-world confirmation that 6th order is the way to go for the best balance of SQ & SPL

These builds from Budge are always fun

Skullcandy buds are hitting hard! I love the range of lows this box is producing.

That box is amazing, looks awesome. When I started car audio I would often wing it with my ports and they would suck. Definitely going to check out those tools!

Hey bro man I wanna tell you I been watching your videos for a while now. Your awesome please keep up the great content I really do appreciate it

props on the very well done video. I like your format. nice to see all the specs scrolling on the side. thanks for the content you're putting out.

I made my first box on 32Hz after watching your video, it has been running for 2 years and is best for spl teaching.thankiu from punjab

The things you stumble onto on youtube. Something sparked some nostalgia and I was reminiscing about my old 6th order I build when I was a kid. I loved the video! Clean, clear and to the point. Lots of good info in there. Make me want to go start messing with car audio again(I still have a old Phoenix Gold MS275 somewhere in the garage I could dig out...). Adding my sub and off to look through your posted videos!

I built a similar designed 6th order for a Sundown U-18. Total volume is almost 10cu ft. Tuned to 24 and 51 Hz. It’s sounds amazing and crushes the lows!

Sorry for this very long comment, but I want you to ask something, but first I explained my - let's call it "situation". Btw, really good explaination of your project - how it works, and / or why you made this box like you made, and the result is MEGA in my opinion. I agree with you on that idea what you explained / showed about the simulator and designer softwares / tools (WinISD + SketchUp) even in your previous videos - it is highly recomended to use these to make a proper a parallel 6th order bandpass box, because they are maybe the most accurate / correct free tools for this, expecially the WinISD. Btw, I figured out something at parallel 6th order bandpasses - I explain it somewhere below, even I made a "test-project" for this, but first to simulation / designer tools. Nowdays there exists many other, even free + online + all-in-one + very easy to use subwoofer box designer tools, some with their own speaker database. One of those tools is speakerboxlite.com website / service. Using just only this one tool I made for my Monacor SP-8/150PRO woofer closed and vented boxes - they were sounding / working OK - so, I can say, this tool is likely usable for these types of boxes. I tried to design for this woofer (and for some other woofers too) 4th order bandpass boxes with speakerboxlite - I not built them, but the accurateness of the simulation results were likely comparable / as accurate as at closed and at vented boxes - so I can say, this tool is usable to design 4th order bandpasses too. On the other hand, I dont know why, but in speakerboxlite the driver's movement is comparable with the WinISD's results if I use the woofer's RMS power in WinISD, but 2-2.5x the RMS power in speakerboxlite - every other graph seems to be OK / similar. But when it comes to simulate 6th order boxes with normal net volume chambers and tuning frequencies - like at the box in your video, the driver's movement in speakerboxlite's simulations (Cone displacement graph) is totally wrong even at the woofer's RMS power level, in WinISD is OK - magenta and light blue lines in the test project below - I dont know why, every other graph seems to be similar to WinISD's... So, thanks to this issue in speakerboxlite, at parallel 6th order bandpasses I figured out something what works in the same way in WinISD too: at a standard 2:1 or 3:1 ratio bandpass boxes if the low-chamber have relatively small net volume too + is tuned very low, and the high-chamber is tuned super-high (200+, or 300+ Hz): the low-chamber works like a widerange but not loud ported box (I call it as "active chamber" because just only this will sound), and the high-chamber acts like just only a driver movement controller (I call it as "passive chamber"). In this case in my opinion it is OK to have such a high tuning frequency for the high-chamber, because on a sub nobody will play so high frequencies like these. Then, if we decrease the high-chamber's net volume and / or tuning frequency, the driver starts to move more at higher frequencies like the low-chamber's tuning frequency - overpasses the X-max even on RMS power, so be careful. The other thing is that the group delay increases maybe because of the reduced driver movement. See the red and green lines in graphs in the test project below: red - an active chamber like a vented box, green - the same active chamber with a 300+ Hz tuned high-chamber. If we have a little higher tuning frequency for active chamber, then we can decrease the passive chamber's tuning frequecy at around 150 Hz without passing over the X-max - the driver's movement increases a little bit at higher bass, the group delay increases too, but it can give few dB (or at least few tents of dB) almost on whole soundrange - in my case between 37 and 88 Hz. In graphs: blue - an active chamber like a vented box, yellow - the same active chamber with a 150+ Hz tuned high-chamber. Here is the test project: https://speakerboxlite.com/project-info/afd0a02cacbb92016973ec9ae019af467233ae54597180a4d0f9514dc82f2a5e/tab-info I designed the whole 6th order box by the yellow lines to show that it is buildable with relatively acceptable outer dimensions. My question: the theory what I explained thanks to that issue, in your opinion is OK, or it is totally wrong?

That thing sounds good. Great build bro.

Very nice.... great job at explaining. 6th orders are awesome. I’m working on a fiberglass 6th for 2 vvx 8s. It’s awesome when you get to the point to understand this stuff enough to build your own. Again I think you are on point. I’m just doing 8s to save space but also to demo and show people what a couple $90 8s can do on music. You know I was thinking maybe when or if you can get around to it... start thinking about 8s and do videos just like you have with the 12s. Skar has a lot now... plus there’s other brands that have killer 8s... they’re usually cheaper than 12s and depending on the box you can still get it to hit lows like 30hz. I just think there’s lots of good reasons why the 8s are a good size to experiment with. I need a practical set up for the most part so I’m always trying to figure out how to get as much as I can out of a system without taking up much space. Working at the hot rod shop was challenging as f!,,, had to keep it small but mean as possible. Thinking along the lines of budget, space, weight, output, and quality.... Skar has a bunch of different levels and options for different applications. Most old dudes that thought they didn’t want a sub... they got a demo and guess what? Most of them got one along with the door speakers and sound deadening. I’ve only heard ix 8s and vvx 8s. I think I watched a video back a couple years ago you had on ix 8. Lot of people argue over if the vvx or ma 8 is better. The vd is shallow but 400w I think. The sdr 8 and svr 8 would be good to test out for budget friendly but decent output. The svr has a bigger coil than the zvx 8 I think. But zvx has like double the rms. The new evl everyone is curious about. You do such a good job man I just think it’d be an awesome series. Thanks for the frequent video posting and quality thorough explanations.

the infrasonics in my headset were bananas!! that shark fin was swimmin'!

Beautiful looking box

This is so beautiful. WOW. I've never seen a real 6th order bandpass box before. Interestingly, I don't believe most people are actually running 3,000 watts to any subwoofers. If you do the math, 3,000 watts at 13 volts is actually 230 amps. If you consider the diameter of the copper windings, they aren't big enough to support 230 amps. If you applied 230 amps to 2 ohms, it would blow up the voice coil instantly. Sound is an AC sine wave and sine waves cannot easily pass current through an electrical coil, due to the impedance (AC resistance) created by the AC frequency. "AC impedance" is why you can plug a transformer straight into the wall socket without it exploding, the transformer winding blocks current from passing through it, acting as a choke filter. The 2 ohm load on paper, is actually hundreds of ohms in operation, which is why the speaker doesn't actually see 230 amps unless you run the subwoofer below the audible level.

this was the video i needed to see... the performance of the dual chambers separately...

I love these videos. you've inspired me to build some boxes. I have two 6.5s I'd love to throw in a band pass

I prefer the graph for 60 Hz. It looks like it rolls off too early for my liking on 50 Hz but whatever your application is it might be just right. You can also play around with chamber sizes to manipulate sensitivity increases. So if the response going up 4-6 dB is too much, you can shrink the chamber.