Hi Justin,
The numbers are the drivers raw motor force product nominalized for impedance and cone area: N/A per .1M². BL²/Re/Sd
I don't think it's coincidental that the 15" TBX and the 18" SW115 are used in very similar boxes...
Art just posted this, I think he read your post here before he posted in the wrong thread by accident...
Thanks for the info & the post, Dan.
"If you run double the RMS power and have limiters set for no clipping, there is still a very real potential of burning the voice coil if the amp is driven in to hard limiting, as is typical of a DJ mashing in to the red for long periods of EDM." -Art
I would like to, in the future, run an amp of double RMS power with very light limiting.
"By the way, most speakers are rated using the AES standard, which uses compressed pink noise with a 6 dB crest factor (normal pink noise is around 12 dB crest factor, still less crest factor than "normal" music), which has only half the average power of a sine wave, which has a 3 dB crest factor." -Art
Good info! Thank you.
"So the short answer about how much power is safe is "it depends"." -Art
Yeah, I was in hopes of someone having previous experience of what temperature was the "fail" zone for certain types of drivers they tested. Perhaps, if someone tested drivers and measured temps while doing so (IPAL users included) and reached the point of voice coil burning/melting and noted the temp. Might be a long shot, but then again - this IS the DIY community I'm talking to
Do you suppose the 18SW100 has the proper amount of force and suspension resistance for the TH-18 mk1? Would you expect this driver to perform any better in a TH w/lower compression, like the TH-18 mk2?
Being fairly similar, how do you see these two (SW) drivers comparing in the same cab (TH-18) with the same voltage in?
Hi Crescendo,
The 18SW100 is a very capable driver and is part of the SW family. Therefore I suggested a relative small "stub" and one disk to start with, for your current TH18. To answer you earlier question, for noSmoking I suggested a higher "stub" and one or two disks to start with, since he uses a more conventional B&C driver. In short that means, I think your 18SW100 would benefit from a TH with a lower compression ratio. I suspect it would also help to increase the excursion and therefore also improve its cooling function.
How your driver compares with the 18SW115, I don’t know. If ‘Klippel’ measurements were available it could reveal some inside info. Judging from the TS parameters your 18SW100 is just a small step down compared to the more ‘TH-ideal’ 18SW118. In your case that means you have a new choice to figure out, go for a second set that gains from coupling and much higher headroom or trade them in for the 18SW118. For both situations there are pro and cons, but hey, what's new huh....
The 18SW100 is a very capable driver and is part of the SW family. Therefore I suggested a relative small "stub" and one disk to start with, for your current TH18. To answer you earlier question, for noSmoking I suggested a higher "stub" and one or two disks to start with, since he uses a more conventional B&C driver. In short that means, I think your 18SW100 would benefit from a TH with a lower compression ratio. I suspect it would also help to increase the excursion and therefore also improve its cooling function.
How your driver compares with the 18SW115, I don’t know. If ‘Klippel’ measurements were available it could reveal some inside info. Judging from the TS parameters your 18SW100 is just a small step down compared to the more ‘TH-ideal’ 18SW118. In your case that means you have a new choice to figure out
, go for a second set that gains from coupling and much higher headroom or trade them in for the 18SW118. For both situations there are pro and cons, but hey, what's new huh....
Wow...Lot of activity here since I last checked.
Dan,
I agree with Djim your calculation is of limited value. driver performance characteristics are just too varied and fluid to reduce "strength" to one set calculation. Although some c alculation such as this may be useful for determining similar driver suitability in certain cabs. Maybe this was what you were doing anyway? Djim also makes a very good point about changes in the driver when away from the rest position. While the specifications near rest are all well and good we don't normally build these types of powerful, large systems to operate them there. One driver may appear to have superior motor strength but what if its xmax rating is exaggerated using any one of the common calculations that have some fudge thrown in and motor BL is down to 50% by xmax and the suspension compliance has dropped to 50% as well. Meanwhile driver 2 with the same xmax rating is calculated by just the geometric coil overhang and at xmax it is only down to 75% of peak BL and 75% suspension compliance? Despite seeming to be the lesser driver judging from the at rest specifications it might actually the superior more linear driver once asked for large amounts of output.
Djim,
You hit the nail on the head with your posts about optimized drivers or TH systems. Some of these modern top of the range drivers are going to perform their best in a cabinet that will not be such a great match for lower cost or more "normal" spec drivers and the reverse also holds true. If you go far enough down the path of designing around one of these drivers you'll soon find that few other drivers are a good drop in in the system at the end of the day and selection of other ones that will will also be comparable in price/performance usually.
Dan,
I agree with Djim your calculation is of limited value. driver performance characteristics are just too varied and fluid to reduce "strength" to one set calculation. Although some c alculation such as this may be useful for determining similar driver suitability in certain cabs. Maybe this was what you were doing anyway? Djim also makes a very good point about changes in the driver when away from the rest position. While the specifications near rest are all well and good we don't normally build these types of powerful, large systems to operate them there.
One driver may appear to have superior motor strength but what if its xmax rating is exaggerated using any one of the common calculations that have some fudge thrown in and motor BL is down to 50% by xmax and the suspension compliance has dropped to 50% as well. Meanwhile driver 2 with the same xmax rating is calculated by just the geometric coil overhang and at xmax it is only down to 75% of peak BL and 75% suspension compliance? Despite seeming to be the lesser driver judging from the at rest specifications it might actually the superior more linear driver once asked for large amounts of output. Djim,
You hit the nail on the head with your posts about optimized drivers or TH systems. Some of these modern top of the range drivers are going to perform their best in a cabinet that will not be such a great match for lower cost or more "normal" spec drivers and the reverse also holds true. If you go far enough down the path of designing around one of these drivers you'll soon find that few other drivers are a good drop in in the system at the end of the day and selection of other ones that will will also be comparable in price/performance usually.
hi all,
Is this a better responce ?
Thanks,
NS
Your measurements appear to be either electrical or acoustic noise and not output captured from a speaker system. Check your input channel is correct and that the microphone is supplied 48v if it needs it.
No it is not normal. There will be some fluctuation (loss of strength) at the extreme ends of the spectrum when measuring the electrical signal such as a loopback <20Hz and >15Khz. If you are monitoring with a volt meter they are typically only accurate at frequencies near 50-60Hz and will start to lose accuracy away from that range.
The 18SW100 is a high quality driver, and if you think about it the difference in the few mm additional excursion capability vs the SW115 is actually small when expressed in dB.
So if that's the case, what's the difference? - rhetorical question there...
It's got MORE of what the TH wants a, stronger motor with a lower Q, more mass, and a bit more thermal capability, and despite it's lower sensitivity it's probably a better driver for your application IMO.
If you were a live band that didn't need below 50Hz what you have would be basically perfect IMO. Sure you might want more, and you could build the boxes and use amps of significantly higher power to get there.
I noticed you crossover at 80Hz, if you had the power to spare there's loads of good kick above that... You really could use the power anyway, but your compressed material makes that sort of risky. If you used the power to alleviate the compression you would benefit from that, but I don't see that happening unless you buy shock collars for the guys behind the mixer... Hey what's that smell???
Wow...Lot of activity here since I last checked.
Dan,
I agree with Djim your calculation is of limited value. driver performance characteristics are just too varied and fluid to reduce "strength" to one set calculation. Although some c alculation such as this may be useful for determining similar driver suitability in certain cabs. Maybe this was what you were doing anyway? Djim also makes a very good point about changes in the driver when away from the rest position. While the specifications near rest are all well and good we don't normally build these types of powerful, large systems to operate them there.
Djim,
You hit the nail on the head with your posts about optimized drivers or TH systems. Some of these modern top of the range drivers are going to perform their best in a cabinet that will not be such a great match for lower cost or more "normal" spec drivers and the reverse also holds true. If you go far enough down the path of designing around one of these drivers you'll soon find that few other drivers are a good drop in in the system at the end of the day and selection of other ones that will will also be comparable in price/performance usually.
Hi Josh,
None of this is new, and all we have to work with is small signal data last time I checked, so yes everything goes out the window when things start moving.
I certainly never implied this data would predict usable or linear excursion.
I've been in the same stance about driver substation
the whole time, and that's part of what the data is about. I never intended it to replace the TSP model for driver selection, but as a supplement to help find more suitable alternates. If you are a builder and you can't afford the top shelf 18" this is a useful method to help select alternates. IMO better to buy a 15" that's strong enough than to go cheap on the 18" and listen to it choke out... Maybe there is a way to get both, by lifting the "V" a little to get a 2:1 ratio and by adding the optional blue panels to increase it for higher ratio's. If these panels are cut in half they be attached afterwards, trough the baffle cut-out.
That seems reasonable. It's good to have an option so you don't end up with an expensive fire starter:
Agreed. I still think you need to get the suspension stiffness and mms in there somewhere though. Maybe it would be easier to develop a stat from the Qes, SD, and FS?
You used the word choking. Have you experienced this or measured the effect? I assume you mean that the motor can no longer control the cone against the forces present on it inside the cab and the output compresses heavily. I have seen some strange compression effects in TH's at VERY loud levels but I am not for certain that it is not related to thermal compression near the driver minimum motion points or reaching some sort of air saturation point inside of the throat or a combination of a couple of things. I don't know if a more powerful motor would have helped. Then again I'm not sure what is going on.
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I take it it's fair to assume the SW100 will be a bit happier in the TH-18 mk2
How your driver compares with the 18SW115, I don’t know. If ‘Klippel’ measurements were available it could reveal some inside info. Judging from the TS parameters your 18SW100 is just a small step down compared to the more ‘TH-ideal’ 18SW118. In your case that means you have a new choice to figure out
They're (SW115) just so expensive...sigh. If I could find some second hand, I would definitely make the move.
And by "much higher headroom," are you referring to the SW100's lower power rating-to-amp power ratio?
Ok, that might be what's going on. Thanks for chiming in, Josh.
The 18SW100 is a high quality driver, and if you think about it the difference in the few mm additional excursion capability vs the SW115 is actually small when expressed in dB.
So if that's the case, what's the difference? - rhetorical question there...
It's got MORE of what the TH wants a, stronger motor with a lower Q, more mass, and a bit more thermal capability, and despite it's lower sensitivity it's probably a better driver for your application IMO.
Well, that is, if you can get the driver to xmax.
On one side of the coin, maybe the SW115 would need gobs [technical term] more power to get to the extra 1.5mm. Then again, does it's greater mass/stronger motor/higher force allow it to achieve xmax easier than the 'less forceful' SW100 (in the same enclosure), thus allowing it to achieve greater spl at the same voltage in?
Does Hornresp show this accurately, btw? If IIRC, the SW115 showed a slightly lower output vs the SW100 in the TH-18 at the same voltage. Perhaps it doesn't.
Side note: wouldn't it be a dream if Hornresp allowed you to input pwr compression figures at 0, -3 and/or -6dB
OK, back on topic..
Use amps of significantly higher power to get....to the same output I would have if using the SW115?? Or do you mean just, - enough to satisfy the SW100?
We cross over around 80Hz at a certain venue, where there are 3-4 15" towers and the sound gets a bit muddied and too concentrated int he 100-125Hz area if we cross much higher.
I understand about the kick, but I don't follow the bit about having enough power..
You really could use the power anyway,
but your compressed material makes that sort of risky. If you used the power to alleviate the compression you would benefit from that, but I don't see that happening unless you buy shock collars for the guys behind the mixer... Hey what's that smell???
Yeah, if my mixer had 5 red lights, they'd easily be lit :/
I'm wondering if this is what I have experienced as well.. A 'different' sound coming out of the mouth at/around the driver's minimal motion point. Another reason that's got me thinking of trying the SW115 in the TH-18. Most of the program material's energy is at the highest compression point of the SW100 in the TH-18. Less so w/the SW115..
Generally speaking pre-flogged drivers are a bad move, unless you re-cone...
When you are at the limit the SW115 will give you more - yes/probably...
Yeah I think the SW100 has the sensitivity advantage, but you are also a bit underpowered.
I think if you had the stack of 9 or 8, you could swing a couple hundred volts at them and be very happy, or very ill, but hey that's good too right.
Ah I C
Well in "most" genres the kick has more energy than the LF, having the headroom to deliver the kick and the restraint to not continually peg the system makes for a good show.
That's a problem for sure. Maybe the subs should be behind the guys spinning.
That's the driver "choking out" at FB due to the huge load imposed by the box, and when FB is in the heart of the program material that's going to result in thermal buildup. Stronger drivers deal with this a bit better but not a whole lot.
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FCK I lost the reply, so this is going to be brief.
Interesting idea I'll look it over.
Qes has Fs,Mms, Re, and BL, but it's the Q of the driver at Fs...The short of it is that the second box went from 6.65 to 9.82 CR without CC, the 18TH115 has a deep cone with huge dustcap! The FR swapped a couple dB >60Hz to plump up 40-60Hz giving it a consumer sub FR. But the sound was compressed at low levels so I was not interested. I tried a 15" on an adapter plate and got the same results... The 15" was selected using this method, it works just fine.
And I may have only this amount of power for a while (2 (two) PLX3402). It's a big reason I'm asking if I'll gain much just by switching out for the SW115 - I won't be giving it more power right away. Perhaps the mk2 TH and the amp power I currently have available will be ok with the SW100 for now..?
Ah, I see what you mean.
The LF content at the DJ booth is so nice - shakes the floor, feet & chest vibrate. It's more, "I need to be louder than the last DJ - no matter what" or the mentality, "red lights equal LoUdeR!" That and ear fatigue from being in the DJ booth with the blaring booth monitor (which is completely controlled by the DJ). I think adding 2 more subs in the current location should be an interesting test
Yep, that is a definite contributor for the magnet temps rising. Come to think of it, the sound I'm referring to is almost exactly the sound of a clipping sinewave. I ran a clipped sinewave signal from my computer to my amp at 2v and achieved the same sound. It's very possible the DJ was clipping his track signal on the night I heard it at the show.
Hi Josh,
The difficulty is you are mixing mechanical and electrical components that can’t be integrated 'here and there' for convenience, in a formula
. Their values are from a different order, mechanical versus electrical. You can use Res, which is the electrical resistive equivalent of the mechanical losses (Rms). Res is therefore coupled to the parameters you suggested/mentioned. Res can be calculated by (Bl*Bl)/Rms. That gives the following formula:
(Bl*Bl)/(Re+Res)/Sd
The problem however, I see too many discussions with a mixture of large and small signals issues and attempts to relate both problems to something simple as Bl at zero movement…
The difficulty is you are mixing mechanical and electrical components that can’t be integrated 'here and there' for convenience, in a formula
. Their values are from a different order, mechanical versus electrical. You can use Res, which is the electrical resistive equivalent of the mechanical losses (Rms). Res is therefore coupled to the parameters you suggested/mentioned. Res can be calculated by (Bl*Bl)/Rms. That gives the following formula:(Bl*Bl)/(Re+Res)/Sd
The problem however, I see too many discussions with a mixture of large and small signals issues and attempts to relate both problems to something simple as Bl at zero movement…
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The stroker showed up quite well.
The magazine was Car Stereo Review and the column was Box Builder.
I think the cool thing was now they showed that balancing the suspension, by adjusting the front spider on the pole piece as was possible, reduced total xmax but increased output by making BL equal in both directions of travel.
the box they put it in was 3.5 cu ft vented and hit 131.5 in car down to 30 hz where it unloaded below tuning. I think they gave it about 500 watts.
I always wanted a Stroker sub!
The magazine was Car Stereo Review and the column was Box Builder.
I think the cool thing was now they showed that balancing the suspension, by adjusting the front spider on the pole piece as was possible, reduced total xmax but increased output by making BL equal in both directions of travel.
the box they put it in was 3.5 cu ft vented and hit 131.5 in car down to 30 hz where it unloaded below tuning. I think they gave it about 500 watts.
I always wanted a Stroker sub!
Hi Etocynned,
Nice example of how excursion not always relates to extra dB's and how a balanced Bl improves output without changing the motor.
The modulation ring as used by 18Sound has a similar function, to equalise the induction between inward and outward movement of the cone. That also improves the output at low frequencies (and lowers the THD).
WE always want something better....
hi,
This is wild ,check out the biggest sub in the world,,,,,IL PIU' GRANDE SUBWOOFER DEL MONDO - by Roberto Delle Curti - Italy
NS
This is wild ,check out the biggest sub in the world,,,,,IL PIU' GRANDE SUBWOOFER DEL MONDO - by Roberto Delle Curti - Italy
NS
Hi Josh,
The difficulty is you are mixing mechanical and electrical components that can’t be integrated 'here and there' for convenience, in a formula
(Bl*Bl)/(Re+Res)/Sd
The problem however, I see too many discussions with a mixture of large and small signals issues and attempts to relate both problems to something simple as Bl at zero movement…
Hmmm I will try that on a few woofers.
Yes...Both mechanical and electrical have to be considered since both are present that is part of the issue. Unfortunately all we have are the small signal parameters since klippel data for most drivers is still rare.
I think you may gain far more by switching amps rather than speakers.
I have QSC PLX 3602 amplifiers (1250 w@4 ohm, 1800 at 2 ohm) rated for slightly more power than the PLX 3402 (1100 @4, 1700 @2).
I have compared them to my Crest CA 9 (800 @4, 1000 @2), the CA9 measures more musical LF output than the PLX 3602.
Of note, the CA-9 does not sound bad in the LF when the clip light illuminates, but the PLX-3602 seems to get "iffy".
Lest anyone thinks I'm just a Crest fanboy, I tested the Crest CC-2800 (965 @4, 1400@2) and it had 5 dB less musical bass output than the CA 9!
The CC-2800 sound goes to crap when the clip light illuminates, I found a TH cabinet that I thought the speakers were crapping out sounded way better (and 5 dB louder) when I used another amp (the SP 4000) for testing.
Interestingly enough, above 100 Hz, the PLX 3602 has noticeably more output than the CA 9. The same can't be said about the CC-2800..
I have been using the CA-9 bridged in to the B&C18SW115-4, no problems with either amp or speaker.
Another great sounding amp is the SpeakerPower SP4000 mono plate amp, (2400w @ 4, 4000 @2) which only weighs 7 pounds, and runs cool while the PLX-3602 at the same output feels like a hair dryer.
The CA-9 bridged mono has just a little more musical LF output than the SP4000, but weighs 44 pounds, and sucks more AC power.
Although all the amps mentioned will bench test at their rated specifications, doing side by side comparisons of amps with music played in to speakers was an eye /ear opener for me, the differences were far greater than I would have thought possible.
Art Welter