I've got a pair of Hawthorne Audio Sterling coaxials on order, rated at 98db/w and good down to probably 40hz.
What I'm wondering is, if I add powered subwoofers to the coaxial drivers and thereby extend FR to 20hz, what effect would this have on total system sensitivity? Would it touch 100db?
I'm looking at a 2W 45 based SET to drive them is why I'm wondering.
Cheers
B.
What I'm wondering is, if I add powered subwoofers to the coaxial drivers and thereby extend FR to 20hz, what effect would this have on total system sensitivity? Would it touch 100db?
I'm looking at a 2W 45 based SET to drive them is why I'm wondering.
Cheers
B.
Hawthornes own sub driver augie is only 88.7db ... I suppose that personally I would use 2 of them pr side 
But I think that Fs=27hz is a bit on the high side with that low SPL, but with its high Qts its probably very linear all the way and may even be crossed a bit higher than normal fore a sub
But I doubt that the coax driver will reach 40hz in OB, or at least it may be down quite a few db
Would be nice to see some measurements
This article is nice with some measurements and explains quite good what is to be expected from the augie subs
http://www.enjoythemusic.com/magazine/equipment/0107/diy_loudspeaker_project.htm
If you want punch and slam I dont see any reason not to use a closed sub with active low xo
But I think that Fs=27hz is a bit on the high side with that low SPL, but with its high Qts its probably very linear all the way and may even be crossed a bit higher than normal fore a sub
But I doubt that the coax driver will reach 40hz in OB, or at least it may be down quite a few db
Would be nice to see some measurements
This article is nice with some measurements and explains quite good what is to be expected from the augie subs
http://www.enjoythemusic.com/magazine/equipment/0107/diy_loudspeaker_project.htm
If you want punch and slam I dont see any reason not to use a closed sub with active low xo
thanks for the replies.
Cant answer you Dave, but it's a good question and has given me something to think about.
Tinitus, I have active dipole subs using Peerless drivers so wont be looking at the Augies. I'm still curious how much adding the subs will increase each speakers measured sensitivity as I will be mounting the Peerless drivers on the same baffle as the Hawthorne coaxial. It could well be that the Coaxials only get down to 60hz, but then adding a sub drivers will add more than the one octave I had guessed at earlier, and so would raise the system sensitivity by even more over the published 98db.
cheers
b.
Cant answer you Dave, but it's a good question and has given me something to think about.
Tinitus, I have active dipole subs using Peerless drivers so wont be looking at the Augies. I'm still curious how much adding the subs will increase each speakers measured sensitivity as I will be mounting the Peerless drivers on the same baffle as the Hawthorne coaxial. It could well be that the Coaxials only get down to 60hz, but then adding a sub drivers will add more than the one octave I had guessed at earlier, and so would raise the system sensitivity by even more over the published 98db.
cheers
b.
Adding a bass driver to boost the LF SPLs will not increase the overall system sensitivity above this point. All adding the extra woofer would do, if it's crossed over right, is increase the useful bass extension of the system before it rolls off by improving sensitivity in these bass regions, where the SI has rolled off. It won't boost the sensitivity of the system as a whole.
Sorry Anderew, I assumed by Dave's response it might add something less than the 2db I was hoping for.
Sorry to tax your patience, but I still dont see how adding a whole octave or two courtesy of an addition 12 inches of driver with 340W behind it, which wasnt present when the measurement was taken, wouldnt increase the speakers sensitivity rating by any appreciable amount. I'm guessing the measurement is taken with some kind of full frequency noise and not a 1khz tone but perhaps I'm wrong about this, or is my reasoning a bit off?
Patient replies appreciated, Cheers
b.
fwiw, reading around now I found a Stereophile article explaining how measurements are taken
"The bandwidth of a loudspeaker will also affect the measured sensitivity if wide-band noise is used as a test signal. Two speakers may sound equally loud on music, but on noise, the model with better extension at the frequency extremes will measure as having a higher sensitivity. What is needed, therefore, is a means of producing a measured sensitivity that correlates with perceived loudness." "Critical-band analyzers not being easy to come by, at Stereophile, I feed the loudspeaker with 20kHz-bandwidth noise at a standard level"
Sorry to tax your patience, but I still dont see how adding a whole octave or two courtesy of an addition 12 inches of driver with 340W behind it, which wasnt present when the measurement was taken, wouldnt increase the speakers sensitivity rating by any appreciable amount. I'm guessing the measurement is taken with some kind of full frequency noise and not a 1khz tone but perhaps I'm wrong about this, or is my reasoning a bit off?
Patient replies appreciated, Cheers
b.
fwiw, reading around now I found a Stereophile article explaining how measurements are taken
"The bandwidth of a loudspeaker will also affect the measured sensitivity if wide-band noise is used as a test signal. Two speakers may sound equally loud on music, but on noise, the model with better extension at the frequency extremes will measure as having a higher sensitivity. What is needed, therefore, is a means of producing a measured sensitivity that correlates with perceived loudness." "Critical-band analyzers not being easy to come by, at Stereophile, I feed the loudspeaker with 20kHz-bandwidth noise at a standard level"
Not yet Cal, not as far as I'm aware of.
These drivers are being made up by Eminence and I dont think even Mr Hawthorn has seen more than the prototype. What little info there is on them on the Hawthorne website has just been received from Eminence in the last week or so. Hopefully more numbers will follow.
cheers
B.
These drivers are being made up by Eminence and I dont think even Mr Hawthorn has seen more than the prototype. What little info there is on them on the Hawthorne website has just been received from Eminence in the last week or so. Hopefully more numbers will follow.
cheers
B.
bvan said:
A sensitivity rating is taken at a specific frequency or small range of frequencies. They are all above where you plan on XOing the driver. The sensitivity will not change, but you gain ability to drive it too higher levels with less likelhood of running out of steam and doppler effects are decreased in the mids.
dave
bvan said:
I think you are confused about the Stereophile quotation. Notice the "what is needed therefore." They are suggesting that the increased measured sensitivity due to a wider bandwidth is NOT an increase in actual "perceived loudness." It's just a phenomenon of the measurement technique, and they are highlighting it as a problem.
Sensitivity is not bandwidth dependant. If it were, woofers and tweeters alone would have very low sensitivity, but that is not the case. As everyone else has said, adding subs won't change your sensitivity at all. That's not to say it wouldn't be worth it.
pj
bvan said:
Use a high pass line level or electronic crossover at 60 cycles (the steeper the better if your looking for output increase) with the subs and your overall loudness will go up a bit cause the little SET won't be choking at the clutch - Think about the small output you now have and the amp and trannies going into saturation trying to drive the bottom end.
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