Series tuned 6th order bandpass experiment

[Triticum Agricolam]

So here's a question, if you built a 6th order box and tuned both chambers to the same frequency, wouldn't it act similarly to a standard ported box but with more output?

No, it would not. The problem is with a series-tuned 6th order, it's impossible to tune both chambers to the same frequency due to the way the two chamber's tunings interact. Lets say you make both chambers 2 cubic feet and you want to tune both to 40 hz using a 6" aero port for each. Now if those chambers were for regular ported boxes the port would have to be around 20" long. So you build your box with both ports being 20" long. What you are going to end up with is a box that's rear chamber is tuned to about 23 Hz and the front chamber is tuned to about 59 hz. This is because the front chamber's port acts somewhat as an extension to the rear chamber's port, lowering its tuning frequency. And the rear chamber's port raises the front chamber's tuning frequency, for reasons I don't understand, but that's what it does. If you try to lengthen the front chamber's port to bring it down to 40 hz you are just going to further lower the rear chamber's tuning. Conversely if you try to shorten the rear chamber's port to bring its tuning up, you will bring up the front chamber's tuning along with it. You are basically chasing your own tail.

Now instead of a series tuned 6th order, lets try tuning a parallel tuned box to the same frequency. This is very much possible, the problem is if you do this both chambers are going to be 180 degrees out of phase with each other and their output will cancel each other out. This is why you don't want to tune the chambers of a parallel tuned box too close together.

If you want to get more output out of a ported box at a single frequency, like you are hoping to do by tuning both chambers the same, just make the ported box bigger.

[Pasta Prime]

So what TS parameters do you look for in a sub that might do good in a 6th?

[Triticum Agricolam]

So what TS parameters do you look for in a sub that might do good in a 6th?

Similar to what would work well in a regular ported box, high EBP, low QTS.

[Pasta Prime]

Thank you. I have had a ridiculous Idea in my head about a 6th and I just might give it a go.

[Triticum Agricolam]

Thank you. I have had a ridiculous Idea in my head about a 6th and I just might give it a go.

No prob, if there is anything I can do to help you, just let me know!

[Jman9112]

So if you tuned the rear chamber at say, 20hz, and the front ended up around 40, would it hit low lows like a boss or would it still roll off as quickly as the ones you guys profiled?

[brent379]

No prob, here are the parallel and series tuned Hornresp inputs:

I'm not sure if I follow you as to which results I may have been overlooking before I built the box.

I don't expect the tuning of one chamber to affect to other with a parallel tuned box so I didn't do any testing with a parallel tuned system. Earlier I think I misunderstood you when you were posting the results of the parallel tuned box with different rear chamber tunings. I was thinking that was a series tuned box for some reason.

not to sound like a total newb, but ive never used hornsrep before and would like to start, is there any like manual available to read on what all these specs or inputs mean and what not????? looks almost like rocket science lol

[Triticum Agricolam]

So if you tuned the rear chamber at say, 20hz, and the front ended up around 40, would it hit low lows like a boss or would it still roll off as quickly as the ones you guys profiled?

The rate at which output rolls off is going to stay fairly constant, the frequency at which it starts can be moved around to where you want by changing the chamber's tuning frequencies. Realistically you can get about one octave of good output before things start rolling off, so 20-40 Hz or 30-60 hz, etc. So in your case, you could tune to 20 & 40 hz (at least in theory) and kill the lows, but output is going to roll off pretty fast above 40 Hz.

Another thing to keep in mind, its not always possible to get what you want with series tuned boxes. You may want to tune to 20 and 40 Hz, but it may not be physically possible using the chamber volumes and port area you want to. Its just the way it is due to the interaction between the ports.

[Triticum Agricolam]

not to sound like a total newb, but ive never used hornsrep before and would like to start, is there any like manual available to read on what all these specs or inputs mean and what not????? looks almost like rocket science lol

Hornresp is very powerful, but it is NOT intuitive. There a pretty steep learning curve to it. Once you get it figured out though, it is not real hard to use.

Probably the best beginners guide is here: http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/36532-hornresp-dum-hmm-everyone.html

The software has been updated with new features since that guide was put out. The series-tuned 6th order modeling capability was added afterwards and is not documented in that guide. However once you have a basic understanding of how Hornresp works, figuring out the series-tuned 6th order stuff is pretty easy. If you need any help with it just let me know and I'll be glad to assist you.

[brent379]

not to sound like a total newb, but ive never used hornsrep before and would like to start, is there any like manual available to read on what all these specs or inputs mean and what not????? looks almost like rocket science lol

Hornresp is very powerful, but it is NOT intuitive. There a pretty steep learning curve to it. Once you get it figured out though, it is not real hard to use.

Probably the best beginners guide is here: http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/36532-hornresp-dum-hmm-everyone.html

The software has been updated with new features since that guide was put out. The series-tuned 6th order modeling capability was added afterwards and is not documented in that guide. However once you have a basic understanding of how Hornresp works, figuring out the series-tuned 6th order stuff is pretty easy. If you need any help with it just let me know and I'll be glad to assist you.

sweet! thank you much man! greatly appreciated