I'm comparing the data sheets for the RS225-8 and the RS225P-8A (and to a lesser extent the RS225-4). The frequency response graphs appear to show a pretty substantial difference in bass. The two aluminum cone versions show basically the same roll-off at the bottom, save for the 4ohm being more efficient overall, as expected. But the RS225P appears to roll off much more gradually at the bottom, having something like a 5dB advantage over RS225-8 from about 80Hz down, and even besting the 4ohm version's output in that range. The FRD files reflect this.
But is it real? I'm modeling them based on the TS params in Basta, and they look roughly the same down low. I also found a 'quick & dirty measurement' comparing the RS225P to the RS225-4. That shows similar slopes for the two, with the 4ohm having a small but constant advantage in output, rather than the paper woofer taking the lead.
So, anyone have any insight or experience with these? I would hope that the manufacturer's measurements would be consistent across the line, but I also notice that the PDF formatting on the RS225P datasheet is a bit different, so I'm guessing they were done at different times, and maybe with a different setup?
But is it real? I'm modeling them based on the TS params in Basta, and they look roughly the same down low. I also found a 'quick & dirty measurement' comparing the RS225P to the RS225-4. That shows similar slopes for the two, with the 4ohm having a small but constant advantage in output, rather than the paper woofer taking the lead.
So, anyone have any insight or experience with these? I would hope that the manufacturer's measurements would be consistent across the line, but I also notice that the PDF formatting on the RS225P datasheet is a bit different, so I'm guessing they were done at different times, and maybe with a different setup?
Just glancing at the specs, the RS225P has a little higher sensitivity, but also a little higher Fs. What Basta shows is about what you'd expect from that: the RS225P is a little louder through most of the range, but rolls off a little sooner, leading it to be about even with the RS225-8 in the lower octaves.
(RS225P blue, RS225-8 green)
(RS225P blue, RS225-8 green)
I would not trust manufacturers frequency response measurements at all below about 200Hz. Accurate measurements become exceedingly difficult to do at low frequency, the fact that there are visible ripples in the RS225-8 datasheet plot means that it can't be trusted down there. Trust the T/S specs and your box simulator. Be aware that T/S specs vary a little with manufacturing batches and what you actually receive might be 1-2dB different in output compared to what you have modelled from the published specs. Account for that in your design. It's also worth noting that a 4ohm nominal woofer has a voltage sensitivity advantage over the equivalent 8ohm nominal woofer, but not a power sensitivity advantage. At 2.83V a 4ohm load draws 2watts of power whereas a 8ohm load draws 1watt. Therefore 4ohm is naturally 3dB louder at the same voltage.
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Hi Erp
I don't have these models but I do have the RS180s-8 and the RS180P-8.
The RS180s, like the RS225, have aluminum cones. The RS180P and the RS225P use composite material comprising of paper, kevlar and glass fibers.
Due to the nature of metal cones, the breakup is quite severe. There's still breakup with the P versions, just not as drastic.
My RS180s aluminum cone has better transient and is clearer in the bass and midrange. This is marginal. Without an AB, it's impossible to tell the difference between the RS180s with the RS180P.
It doesn't mean the RS180s is always the best choice. It all depends on what I'm doing. In my latest design Raven-CAT, I used the RS180P. The RS180s breakup is too much to handle with a 1st order.
Hope it helps.
Regards
Mike
I don't have these models but I do have the RS180s-8 and the RS180P-8.
The RS180s, like the RS225, have aluminum cones. The RS180P and the RS225P use composite material comprising of paper, kevlar and glass fibers.
Due to the nature of metal cones, the breakup is quite severe. There's still breakup with the P versions, just not as drastic.
My RS180s aluminum cone has better transient and is clearer in the bass and midrange. This is marginal. Without an AB, it's impossible to tell the difference between the RS180s with the RS180P.
It doesn't mean the RS180s is always the best choice. It all depends on what I'm doing. In my latest design Raven-CAT, I used the RS180P. The RS180s breakup is too much to handle with a 1st order.
Hope it helps.
Regards
Mike
Thanks, guys. I was leaning toward trusting the modeling, just wanted a second opinion.
I'm looking at low-passing this at around 400Hz 2nd order, so breakup shouldn't be too big of an issue anyway, correct? So then I'd just be looking at a little better transients & clarity with the aluminum cone vs a little higher sensitivity with paper, but pretty damn close overall, right?
I'm looking at low-passing this at around 400Hz 2nd order, so breakup shouldn't be too big of an issue anyway, correct? So then I'd just be looking at a little better transients & clarity with the aluminum cone vs a little higher sensitivity with paper, but pretty damn close overall, right?
I did some simulations based on Dayton's T/S. You get a lower F3 with the RS225-8. Box is slightly larger.
RS225-8 VOL= 45L F3=30Hz
RS225P-8A VOL=40L F3=40Hz
RS225-8 VOL= 45L F3=30Hz
RS225P-8A VOL=40L F3=40Hz
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