# Design Phase



## Guest (Jan 25, 2007)

:nerd: Hello everyone, I'm brand new to HTS. I've spent hours over the last few days learning as much as I possibly can prior to my sub build. Wow, where to start...

I have decided to go with either a ported or PR enclosure rather than sealed. I ponied up the bucks for a 15" TC 2000 (clench!!) and am watching several deals on the EP 2500 amp on eBay.

The TC Sounds site recommends a 6 sq ft enclosure for ported or PR setups for this driver tuned to 17-18hz, so that's about what I think I'll go with. I called for more info before buying and had a really informative conversation with their tech (his name is Thilo) who after patiently answering my endless stupid questions, suggested that I might try a vented box utilizing three 4" ports (this is what TC recommends) and get plugs for them to more or less create a sealed enclosure for music vs HT. This sounds like a novel approach. I would love to hear opinions on this or if anyone has ever tried or heard of anyone trying this. I did go into the hardware store to look at tubes and plugs and wasn't too excited about the caps, plugs and fittings for the 4" pvc ports. 

I'll probably have a LOT more questions as I move forward with this but I'd like to hear any and all suggestions regarding this open/plugged port issue first. I will say at this point I'm not leaning toward the sonotube design, as I don't want a tall sub. That said, I don't yet know what configuration/demensions I will go with, but would like to stay around a volume of 6'.

Thanks in advance for any input you all might have!


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## SteveCallas (Apr 29, 2006)

Tuning a 6 cubic foot enclosure to 17.5hz using three 4" diameter ports means each port would have to be ~52" long. That wouldn't fit inside the enclosure and first port resonance would likely be audible at ~130hz. I'd aim to keep port length <36". Additionally, the natural FR doesn't appear that it would result in an in room FR that extends flat too deeply, but that may just be personal preference.

The thing is, when using a relatively small ported enclosure - and 6 cubic feet is relatively small for a ported 15" - you can't effectively get the most out of a low tune. As the tuning drops, enclosure size would ideally increase, boosting low end sensitivity, keeping FR relatively flat and deep, and allowing for large diameter porting since the amount of air moving through the port will be increasing as well. A single larger port will offer less compromise than several smaller ones.

Hope that helps.


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## Guest (Jan 26, 2007)

Thanks Steve that helps. I downloaded a couple of different design tools that I fumbled with and got different numbers from each one. I did experiment with the Sonosub calculator and if I understand it correctly I think I could go with a 24" dia tube, 36" high for a volume of roughly 9ft3 or 260L. with a 6" port approx 16" long, the sub would be tuned at about 16Hz. This was with the default driver, the SS RPL 15 which I believe is fairly similar to the TC 2000 I have ordered.

I was shying away from the sonosub design because it seemed like most of them are quite large speakers 5' tall or more! I have read many threads explaining why the extra internal volume helps for low Hz tuning and fairly flat response, so by going with a smaller (shorter) tube with a volume of 260L or so, would I have to sacrifice in the higher registers - say above 60 or 80Hz?

I should mention that I do have a 10" JBL sub which was not handling the low freq very well during movies, so I thought I would put an in-line high pass filter (30Hz) on that one and build the larger sub to handle the really low signals. My viewing room is 13X21X8.5 or 2320 sq ft. Does this sound reasonable?


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## SteveCallas (Apr 29, 2006)

A TC 2000 15 or RLP-15 sub will outclass the 10" JBL sub is every way, shape, and form :T The TC 2000 15" svc in 260 effective liters with a 16hz tuning will work nicely, but the 6" diameter port will need to be longer than 16", it would be more like 27-28". The issue that arises is that the tube is only 36" long: subtract the thickness of the endcaps and the distance the driver extends into the enclosure, and your port won't have much brathing room. You could tune it to 18hz and still have a nice looking response, but then the issue arises that you probably need a high pass filter. Member chasw might be selling some and that could be an option. A lot of us get away with no highpass by using really low tunes.

Is the 36" your max allowable height? And keep in mind that a 24" diameter tube is fairly wide.


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