Dual RS 15 HF Sub

[elambert]

Ok guys I need some input. I have been planning a new HT sub for a while now after I built my Quatro 15/ plate 240 combo a while back. I am happy with the quatro but it just simply isn't enough.

I am ordering the drivers tomorrow and think I have settled on the Dayton RS 15 HFs. With the price what it is... I have modeled them in WinISD and have come up with the following idea so far:

2 subs in one box, push-pull configuration, 25 ft^3 tuned to 15HZ. This should give an F3 of 15HZ. Suggestions?

TIA Ethan

Btw, for right now they will be driven off an Altec Lansing 9444A amp, roughly 600 watts on tap at 8 ohm. Don't know if it's stable to 2 ohm but I don't think so. It's 300 x 2 at 4 ohm or 600 x 1 at 8 ohm bridged.

[joecarrow]

Have you considered stereo subs?

-that's one enormous box
-the RS subs can play higher in frequency than most
-can help with room placement
-your amp can do 2x300

Another thought- how long is the port?

[elambert]

Definitely considered stereo, however my space is limited except for one spot. I'm still working on the ports. It will definitely take some serious ports. Some serious air movement happening.

[ThomasW]

2 subs in one box, push-pull configuration, 25 ft^3 tuned to 15HZ. This should give an F3 of 15HZ. Suggestions?

For the same money as the 2 RS12"s, you could buy one SoundSplinter RL-p15" and have a much, much, smaller box with the same output.

[elambert]

Very good point Thomas. I had forgotten about those drivers. I went back and modeled the sound splinter driver however the low end extension is not nearly as comparable as the twin RSs. Now I do have some decisions to make. Hmmm.

[SteveCallas]

I am happy with the quatro but it just simply isn't enough

In terms of what - output, extension, sound quality, or all of the above?

I wouldn't really consider the HiFi15 if you want to get significantly more output.

[ThomasW]

I went back and modeled the sound splinter driver however the low end extension is not nearly as comparable as the twin RSs. Now I do have some decisions to make. Hmmm.

Computer sims are anechoic models, they fail to take the effects of room gain into account. Also every sub benefits from the judicious use of EQ.

[elambert]

Well to answer the question, I am unhappy or I should really say unsatisfied with all of the mentioned aspects of the quatro. It sounds pretty good, reaches reasonably low with reasonable output. I guess I don't want reasonable, I want more without breaking the bank in terms of driver cost.

I am very well aware of eq'ing subs. My setup is run through a PC XO system that I use to eq the quatro currently. The rest of the system isn't worth mentioning it's so bad. But I have to start somewhere and I thought the quatro would be a good start and it was to some extent. Just enough to get me wanting more.

[SteveCallas]

Ok, and what's your budget for this new sub?

[soho54]

I wouldn't really consider the HiFi15 if you want to get significantly more output.

What do you mean by this? Two RS 15" get a good 2db of output at lower freq and are about 2db short on upper bass compared to a single RL-p15. They're about the same price wise, and the RS requires a less robust amp.

[soho54]

elambert- The difference really is negligible. The RL-p15 just needs half the space, and a little more power. The two RS 15" might get the SQ edge at normal levels though.

The difference is not as great as it looks. The D2 at 260l might even close the gap a little more.

[SteveCallas]

I wasn't necessarily comparing it to a single RLp15, I was just looking at it from the overall view that he wants a lot more output than the Quatro.

[Brian Walter]

What do you mean by this? Two RS 15" get a good 2db of output at lower freq and are about 2db short on upper bass compared to a single RL-p15. They're about the same price wise, and the RS requires a less robust amp.

I have been going through quite a few sims myself lately trying to figure out what is the best route to go, and I've been really disappointed in the RS15HF. They aren't too bad in a sealed box, but they seem to need a rather big box, either sealed or ported.

I'd like to see your sims that show the dual RS 15's outperforming the RL-p15; That's not what I found, but there are so many options in box size tuning, EQ, etc., that I could have easily missed something.

I've finally decided to go ahead and build a Quatro 15. I'm going to put it in a 6.2 cf (net) box, tuned to 20 Hz, with a 4th order HP at 18 Hz (Q=1.0) and a 4th order LR LP at 49 Hz. Based on the sims, I can get 95 db at 15 Hz, 107.7 db at 20 HZ and 110.4 @ 30 Hz, all with only 160 watts, and not exceeding xmax. This will be crossed over to a pair of RS-3 ways at 50 Hz. If this enough, I'll either build another Quatro or switch to the SS RL-p15. One of the reasons I've decided to build the Quatro is that I've already got the parts, I've had them for about a year now, but built my 3 ways first.

Brian Walter

[soho54]

but they seem to need a rather big box

This is true. :B

I'd like to see your sims that show the dual RS 15's outperforming the RL-p15

I didn't mean to imply that they would outperform an RL-p15. They can just hang when grouped in pairs, when given enough space. Check the pic in post 11 for a graph.

Steve, AOK. :T

[Brian Walter]

I must have been writing when you posted the graph. I see that they do perform quite well in that big of a box. I guess when I came up with needing 25 cf I kind of ruled it out as there is no way my wife would go along with that. But I could conceivably go with an IB setup.

[soho54]

Brian Walter, the RS15 HF really wants a lot of space per driver. You don't have to go to quite these sizes though. 7-10cu ft per driver is good. Less with the HO. The RL-p15 sets the bar pretty high. You really have to wring everything out of the RSHF to come close to the performance of the mighty SS.

IB is always highly recomended. :T

[elambert]

elambert- The difference really is negligible. The RL-p15 just needs half the space, and a little more power. The two RS 15" might get the SQ edge at normal levels though.

The difference is not as great as it looks. The D2 at 260l might even close the gap a little more.

Well the D2 is not an option due to my current amplification setup. What are you using to model with? The reason why is my graphs on WinISD look nothing like yours. Attached are my graphs, blue line representing the twin RSs. Yellow is a direct copy of your specs on the RL-ps. In this graph however, both units are used at 600w total power instead of the split different wattages shown in yours.

[elambert]

Ok, and what's your budget for this new sub?

Budget is roughly $300 for driver/s. Extra costs such as the wood etc. will be factored in over several weeks so whatever I need there is not as critical.

There is no extra budget right away for amplification. I am pretty much well stuck with what I have for right now. I would like in the future to upgrade that as well however it will have to wait.

[soho54]

elambert, don't use the RP-l15 specs that came with WinISD. They are wrong. That could be the problem.

I'll check it out later today in Win and see if I can find the problem. :T

[elambert]

I modeled in WinISD with specs I put in from their website and with the preloaded params. I do think that particular graph was with the preloaded params though.

[soho54]

elambert, just got home.

What are you using to model with?

UniBox