Subwoofer question, RSS315 4 or 8 ohm?

[winkun]

I'm planning a subwoofer build like AVDweeb in this thread: http://techtalk.parts-express.com/sh...6&postcount=37
O Audio 500w BASH, Dayton RSS315HF-4 and 2.0 cu ft cabinet. It will be used mostly for classical and jazz music with my Econowave Delite 10s. I don't have a HT but I do run my DVD audio through my system too.

I just noticed that the RSS315HFA-8 is on special for ~$20 less than the 4 ohm version.

Besides the usable frequency range difference (4 ohm 23-1000Hz and 8 ohm 25-1500Hz) and giving up 175 watts on the O Audio amp, is there anything else? I did notice that the THD of the BASH amp is less going into an 8 ohm load, but that probably is not a big deal with a sub, right?

I'm kinda new at all this and really appreciate the opportunity to ask questions,,, I'm open to all suggestions,,,

-winkun-

*edit* These subs are both the HF version, not HO. Cabinet will be sealed.

[Pete Schumacher ®]

I'm planning a subwoofer build like AVDweeb in this thread: http://techtalk.parts-express.com/sh...6&postcount=37
O Audio 500w BASH, Dayton RSS315HF-4 and 2.0 cu ft cabinet. It will be used mostly for classical and jazz music with my Econowave Delite 10s. I don't have a HT but I do run my DVD audio through my system too.

I just noticed that the RSS315HFA-8 is on special for ~$20 less than the 4 ohm version.

Besides the usable frequency range difference (4 ohm 23-1000Hz and 8 ohm 25-1500Hz) and giving up 175 watts on the O Audio amp, is there anything else? I did notice that the THD of the BASH amp is less going into an 8 ohm load, but that probably is not a big deal with a sub, right?

I'm kinda new at all this and really appreciate the opportunity to ask questions,,, I'm open to all suggestions,,,

-winkun-

The HF subs have thinner cones, and will more likely suffer difficulties with small sealed enclosures. The HO variety is designed for use in small sealed enclosures.

I use my RSS315HF-8 as a woofer in a 3-way (see my avatar) and it is coupled to a passive radiator in 3.3 cubic feet. The PR tunes the volume to 17Hz, with the overall response looking very much like a sealed alignment.

[Ryan_M]

I use the 4ohm versions. I did have problems with it oils canning when running a single sub in a small sealed box and driven really hard. But I switched to using two of them to get better response, by breaking up room nodes, and each sub only had to work half as hard so no more oil canning issues as loud as I cared to crank it. 2 was miles better bass response than a single.

I don't know what you have for space or what your future plans are but the 4ohm version will get the most out of the amp vs. the 8ohm version. But the 8ohm versions give you a little more flexibility in that you can add another - if it might be in your plans - and still use the same amp.

FWIW I've read the HF version is better for music than the HO, with the HO more intended for HT and making stuff go boom. That's third hand info and I don't know how accurate it is but it's how I ended up choosing the HF over the HO version. Another FWIW, Zaph likes using the HF. (about 1/3rd way down the page)

[winkun]

Thanks Pete, The subwoofers I'm considering are both the HF version. The 8 ohm is called an HFA, I'm not sure what the A means.

RSS315HF-4 or RSS315HFA-8

I considered building Darren's "The Drake" using the HO version, but I'm thinking that for my listening tastes I will be better served using the HF.

I ran across your Byzantium build thread when I was searching to see if my 8 ohm vs 4 ohm question already had an answer. My goodness that looks like a beast! I plan to browse all 10 pages of the build.

[winkun]

Thx Ryan,,,

Right now it will be in a medium size living room, maybe 20'x25' with 8' ceiling. I am planning a move next year to a much larger listening space so two separate subs are a real possibility eventually. I guess I ought to be considering an active crossover and a biggie stereo pro amp instead of the plate amp, right? $$ not a huge issue, but I am frugal at heart.

[Pete Schumacher ®]

Thx Ryan,,,

Right now it will be in a medium size living room, maybe 20'x25' with 8' ceiling. I am planning a move next year to a much larger listening space so two separate subs are a real possibility eventually. I guess I ought to be considering an active crossover and a biggie stereo pro amp instead of the plate amp, right? $$ not a huge issue, but I am frugal at heart.

If it's at all possible, position the sub right next to where you sit. You'll minimize power requirement, and you'll be sitting near field, which will help smooth out the bass response at your seat.

[Jethro]

I'm planning a subwoofer build like AVDweeb in this thread: http://techtalk.parts-express.com/sh...6&postcount=37
O Audio 500w BASH, Dayton RSS315HF-4 and 2.0 cu ft cabinet. It will be used mostly for classical and jazz music with my Econowave Delite 10s. I don't have a HT but I do run my DVD audio through my system too.

I just noticed that the RSS315HFA-8 is on special for ~$20 less than the 4 ohm version.

Besides the usable frequency range difference (4 ohm 23-1000Hz and 8 ohm 25-1500Hz) and giving up 175 watts on the O Audio amp, is there anything else? I did notice that the THD of the BASH amp is less going into an 8 ohm load, but that probably is not a big deal with a sub, right?

I'm kinda new at all this and really appreciate the opportunity to ask questions,,, I'm open to all suggestions,,,

-winkun-

*edit* These subs are both the HF version, not HO. Cabinet will be sealed.

I was one of the first to use the 12HF in PE's 2 cu ft sealed cabinet with a 500W plate amp. The setup has done very well for several years now -- it is musical first, but still packs plenty of authority for HT use. No issues whatsoever using the HF in "small sealed enclosures".

I would suggest going with the 4-ohm model, if you haven't already made your decision. In looking at the THD numbers on the BASH amp, you really are comparing apples to oranges when comparing 8-ohm vs. 4-ohm specs. You are comparing a spec at 325W vs. a spec at 500W -- what is the 4-ohm THD spec at 325W? Likely the same as the 8-ohm spec, except there's still 175W worth of headroom with the 4-ohm option -- something you will never get back with the 8-ohm option. Not to mention the fact that the difference between 0.05%THD and 0.3%THD is inaudible.