Dayton RSS390HF-4 Design Help

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Hi,
I've got a dayton 15" hf subwoofer and I'm planning on sticking it in a 250 litre ported enclosure measuring 53 x 53 x 106cm powered a dayton hpsa500. I got started on the build earlier today and got all the 3/4" mdf cut out, but I couldn't make a decision on the ports. I plugged the figures into WinISD and it says I can use two 3" ports or two 4" ports. Will there be any differnce in perfermance depending on which ones I choose? Also, what would be a good frequency to tune the box to? I see a lot of people with similar designs have tuned their to around 17 or 18hz but is there really a point going down that low, since this will mainly be for music with maybe the odd movie.
Thanks
 
Hi,
I've got a dayton 15" hf subwoofer and I'm planning on sticking it in a 250 litre ported enclosure measuring 53 x 53 x 106cm powered a dayton hpsa500. I got started on the build earlier today and got all the 3/4" mdf cut out, but I couldn't make a decision on the ports. I plugged the figures into WinISD and it says I can use two 3" ports or two 4" ports. Will there be any differnce in perfermance depending on which ones I choose? Also, what would be a good frequency to tune the box to? I see a lot of people with similar designs have tuned their to around 17 or 18hz but is there really a point going down that low, since this will mainly be for music with maybe the odd movie.
Thanks

Howdy TM, I have used that driver many times. It's on my best-o-all-time list.

Ports: minimum of two 4" ports with flares. Better: one 6" with flare. The point is to keep air velocity low, less than 15m/s for both the double 4" or single 6".

Tuning: for that driver in that box ~18Hz is good, I would not go above that. The point is that you never want to send signal below tuning and most of the time don't want signal near tuning because the group delay at tuning will smear the sound. Plus that amp has a HP filter at 18hz 2nd order which will work well with a 18hz tuning. You have a great driver that likes a big box and a low tuning, give it what it wants and it will move you, literally.

I really would go with the 6" port X 25" long for 17Hz tuning
 
Hi, thanks for the reply.
I had thought about using a single 6" port but it seems to hard to find a good one. I can find 6" cardboard postal tubes and fan ducting which are quite cheap but not rigid enough for the purpose. The best I could find is a 6" acrylic tube with 5mm walls, its a bit pricey but would it suitable for the port if its properly supported by the bracing?

I can't seem to find any flares for a 6" port, will it be fine without one. Although I was planning on routing the mdf around the port hole which might have a small effect.

I was also wondering what the best way to mount the the driver is? It seems to be between hurricane nuts and wood screws.

Thanks
 
Thanks for replying so fast
After another search it turns out you can find 6" pvc over here, only the cheapest I could find would be around £50 for one metre plus shipping, which is quite a bit more than I wanted to pay. The 6" acrylic with 5mm walls would work out at £32 for half a metre, which is still expensive but seems like the better option.

Would these hurricane nuts be ok: (32) 1405NT3 1/4-20 x 5/16" 3 Prong T Nut Tee Nut | eBay
 
I'm not sure, a slotted port seems very time consuming and compliciated. Especially since the range of tools available to me is quite limited.

The postal tubes look good. However, the minimum quantity thay will sell is 8 and I don't really know what I would do with the other seven.

I think my best bet would be to go with the acylic I suggested: 150mm x 5mm Clear Acrylic Tube Plastic Perspex 500mm | eBay
Its got 5mm walls so should be fairly rigid, and it will save me the cutting because its already 500mm long which is the length WinISD gave me for around 17 to 18hz tuning . I'll make sure its will supported by the shelf bracing to avoid unwanted resonance since its not as solid as pvc pipe.
 
The postal tubes do seem like the cheapest option, although I wish they sold them singally instead of in packs. I have searched around car audio websites and I can find 6"ports but they only offer them in lengths of 150mm so I will still need to extend them with something. I could settle for two 4" flared ports but since I will need two of them it might work out quite a bit more expensive.
 
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