This is true if you compare by given Xmax. But again B&C is using a more positive formula for the Xmax then Eminence (or 18Sound) does.
B&C Xmax = (Hvc – Hg)/2 + unknown variable
18Sound = (Hvc - Hg)/2 + Hg/4
Eminence Xmax = (Hvc - Hg)/2
So as long you want to compare the B&C in a 'fair' theoretical competition you need to know it’s unknown variable… For example, you can compare the Eminence 3015LF to any RCF or 18Sound if you correct its Xmax to RCF/18Sound standards.
Xmax 3015LF (Hvc - Hg)/2 = 9,6mm
Xmax of the 3015LF by RCF/18Sound Standards= (Hvc - Hg)/2 + Hg/4 = 10,8mm
In the sim I allowed excursion to go to about 15mm, in between the Xmax spec of 14 and the Xvar of 16.
The speaker has an Xlim of 30mm (60mm peak to peak), a mm one way or another is small potatoes. As I mentioned before, sitting on the shop floor, no box at all, the BC18SW115-4 had only about 30mm peak to peak with 50V input at 11 Hz, no sounds of distress or harmonics at all, the amplifier fan made more noise.
I own lots of Eminence speakers, the BC18SW115-4 makes them seem a bit pale by comparison.
Anyway, DSL decided to use the BC18SW115-4 after using the 18 Sound 18NLW9600-4,as it worked better in the TH-118, that was enough to convince me
.I know the B&C’s are worth considering as we have faced similar test results between 18Sounds and B&C’s (although not in all designs).
Actually, I still think there is more relation between Xlim and distortion/max pwr handling than there is between calculated Xmax and distortion/max pwr handling. I found out that Djk’s statement about the differences in magnetic field do play an important part. More technical, the deformations in magnetic field within the gap (and between magnet and iron core) + the magnetic field outside the motor system are very important to THD (in other words: non-linear movement). This factor doesn't even play part in formulas as used by Eminence, 18Sound or RCF... Even if you introduce the BL and/or top-plate within the formulas it still isn't a factor.
It’s not I want to doubt your real life measurements findings at all, Art!
It’s just the one-on-one Xmax comparisons I have a problem with. This Xmax doesn't tell the truth about the real capabilities of a driver, I think. Especial for drivers in PA. And yes, I’m aware an 18” does have a 'little' more air movement than a 15” and that 1.2mm in favour of the 3015LF wont change that.
Actually, I still think there is more relation between Xlim and distortion/max pwr handling than there is between calculated Xmax and distortion/max pwr handling. I found out that Djk’s statement about the differences in magnetic field do play an important part. More technical, the deformations in magnetic field within the gap (and between magnet and iron core) + the magnetic field outside the motor system are very important to THD (in other words: non-linear movement). This factor doesn't even play part in formulas as used by Eminence, 18Sound or RCF... Even if you introduce the BL and/or top-plate within the formulas it still isn't a factor.
It’s not I want to doubt your real life measurements findings at all, Art!
It’s just the one-on-one Xmax comparisons I have a problem with. This Xmax doesn't tell the truth about the real capabilities of a driver, I think. Especial for drivers in PA. And yes, I’m aware an 18” does have a 'little' more air movement than a 15” and that 1.2mm in favour of the 3015LF wont change that
.Post #440
Hi Weltersys,
"...Atc is defined as “Throat chamber average cross-sectional area normal to axis (sq cm)."
Do you know how that relates to Atc in a reduced throat area TH, that is, an exit smaller than the cone area ?
Why did you model the SS15 with hyperbolic and exponential flares rather than a series of conical expansion as it seems to be?..."
Atc refers to the cross-section (normal to the drivers axis) of the actual throat chamber. Together with Vtc it defines the depth of the throat chamber for Hornresp. In reality this is not quite what we are looking at, as we are looking at the truncated cone's volume plus any contribution from spacer boards, etc., e.g.: as in the Furybox.
Basically all tapped horns will have a throat area (S1) that is smaller than the cone area (Sd). The driver vents by definition into the "general" throat area at S2, and here the designs ususally show a compression factor of two to three (Sd/S2).
The coupling from the throat chamber to the horn @ S2 occurs through an opening defined by Ap1 (cross-section) and Lpt (length) of coupling member.
It's easy to get into semantics here, but that's unavoidable when you are looking at the programming side of it.
As to the taper or flare rate: you have a choice of Exp/Con/Par. Smarter guys than me have figured out that the taper we are building with two parallel sides and one tapered side is actually a parabolic taper, thus Par.
But, sometimes you have a part of the horn which is better described by another flare rate. So you may end up with L23 being best served with Par and L45 looking closer in Exp. Hornresp models are by definition simplified from the more complete simulations as they are available in AkAbak.
As to my model of the SS15: in the single sheet challenge threat Post #74 I indicated: "...Hi jbell, I took your notes and "refreshed" the drawing from Post #63. The Hornresp simulation does not change sufficiently to warrant spending any more time on it....".
The SS15 is fine as it is, a more in depth analytical workup would require moving the model into AkAbak (in Hornresp use: File/Export/AkAbak Script/File Name (less than 8 characters)). It also would mean redrawing, etc..
The back and forth between these two threads is becoming bothersome. I'll try to look at your simulation as soon as my computer allows me to download it.
Anyway, I hope this helps.
Regards,
Hi Weltersys,
"...Atc is defined as “Throat chamber average cross-sectional area normal to axis (sq cm)."
Do you know how that relates to Atc in a reduced throat area TH, that is, an exit smaller than the cone area ?
Why did you model the SS15 with hyperbolic and exponential flares rather than a series of conical expansion as it seems to be?..."
Atc refers to the cross-section (normal to the drivers axis) of the actual throat chamber. Together with Vtc it defines the depth of the throat chamber for Hornresp. In reality this is not quite what we are looking at, as we are looking at the truncated cone's volume plus any contribution from spacer boards, etc., e.g.: as in the Furybox.
Basically all tapped horns will have a throat area (S1) that is smaller than the cone area (Sd). The driver vents by definition into the "general" throat area at S2, and here the designs ususally show a compression factor of two to three (Sd/S2).
The coupling from the throat chamber to the horn @ S2 occurs through an opening defined by Ap1 (cross-section) and Lpt (length) of coupling member.
It's easy to get into semantics here, but that's unavoidable when you are looking at the programming side of it.
As to the taper or flare rate: you have a choice of Exp/Con/Par. Smarter guys than me have figured out that the taper we are building with two parallel sides and one tapered side is actually a parabolic taper, thus Par.
But, sometimes you have a part of the horn which is better described by another flare rate. So you may end up with L23 being best served with Par and L45 looking closer in Exp. Hornresp models are by definition simplified from the more complete simulations as they are available in AkAbak.
As to my model of the SS15: in the single sheet challenge threat Post #74 I indicated: "...Hi jbell, I took your notes and "refreshed" the drawing from Post #63. The Hornresp simulation does not change sufficiently to warrant spending any more time on it....".
The SS15 is fine as it is, a more in depth analytical workup would require moving the model into AkAbak (in Hornresp use: File/Export/AkAbak Script/File Name (less than 8 characters)). It also would mean redrawing, etc..
The back and forth between these two threads is becoming bothersome. I'll try to look at your simulation as soon as my computer allows me to download it
.Anyway, I hope this helps.
Regards,
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Hi Weltersys,
I messed around a little with the 18SW115, and it is one incredibly driver. I'll attach a Hornresp export I made. Just for kicks try what it looks like in multiples of 4. When in the SPL window: Tools/Multiple Speakers/4 parallel, 30Hz through 300Hz, basically above 140dB with room to spare. And that's without trying hard(and without drawing, folding, matching, building, testing).
Regards,
I messed around a little with the 18SW115, and it is one incredibly driver. I'll attach a Hornresp export I made. Just for kicks try what it looks like in multiples of 4
. When in the SPL window: Tools/Multiple Speakers/4 parallel, 30Hz through 300Hz, basically above 140dB with room to spare. And that's without trying hard(and without drawing, folding, matching, building, testing).Regards,
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56 exceeds xmax a bit, and I'm paranoid. 50v is where I'm currently limiting the stadium system.
In the sim I allowed excursion to go to about 15mm, in between the Xmax spec of 14 and the Xvar of 16.
The speaker has an Xlim of 30mm (60mm peak to peak), a mm one way or another is small potatoes. As I mentioned before, sitting on the shop floor, no box at all, the BC18SW115-4 had only about 30mm peak to peak with 50V input at 11 Hz, no sounds of distress or harmonics at all, the amplifier fan made more noise.
I own lots of Eminence speakers, the BC18SW115-4 makes them seem a bit pale by comparison.
Anyway, DSL decided to use the BC18SW115-4 after using the 18 Sound 18NLW9600-4,as it worked better in the TH-118, that was enough to convince me
Really...I did not know that DSL had switched to the B&C. Interesting.
The top 18" and 21" drivers from both respective companies simulate within a gnats hair of each other in most alignments. There is a full test in Voicecoil mag by Vance D. with Klippel reports for both the 18sw115 and the 18nlw9600 (I figure that you are aware of this but others may not be.). Overall I thought the B&C was very slightly better judging from the symmetry of the BL/x, LE/x, and KMS curves. Both are monsters though. BTW I have a pair of the B&C 21sw152's and I have a similar "experiment" finding as you did. I free air tested them and they were great up till about 30mm p2p, at about 40mm p2p (guesstimate) they exhibited some motor air flow noise and a little suspension noise. I had the driver connected to a single channel of a QSC pl9.0 run off of 240v and with a 10hz sine wave I was able to drive the amp into clipping without damage to the driver. It seems to brick wall at about 40mm p2p or a little past and further power increases just heat up the coil while not producing appreciably more excursion. The last 3 or so increases in volume did not appear to produce any further cone excursion. Moral of the story is that it seems like you would have to do something really dumb to mechanically damage these drivers. To me it almost appears as if there is a braking action built into the motor perhaps as part of the split winding technique they mention? That is pure speculation on my part. The BL curve is much flatter than a straight overhung design typically is though.
Sorry for the off topic guys.
18 Sound has many 15 inch drivers.
Using an 18 inch driver in a design like the SS15 would require a 2 or 3 inch depth increase, which would increase overall path length and volume, which would lower the LF corner even more than the substitution of a BC18SW125.
Using the design "as built" an 18" could be put in if a "doughnut" adapter was used between the 18" and 15" baffle cutout, but would hang out the front by a couple inches, and would look fuggly.
Dave, one of the cheapest 18Sounds (type:15W700) works fine in a SS15. The 15W700 comes close to the 3015LF parameters that are used in HornResp for the SS15. Don't be afraid for its relative low Xmax of 6,5mm (190Watt). You can power it safe with 500 watts music power and it won't be damaged.
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Dave; You posted in the wroung thread. But.............
You can not put a 18" speaker in the SS15 but it would fit in my vershoin of the SS15.
The speaker deck in mine is 20" by 17.5". I looked at it today for you.
My box is posted in the SS15 thread and I will be starting a new thread for my box.
Andy
You can not put a 18" speaker in the SS15 but it would fit in my vershoin of the SS15.
The speaker deck in mine is 20" by 17.5". I looked at it today for you.
My box is posted in the SS15 thread and I will be starting a new thread for my box.
Andy
i'll bite on this one. what in particular is wrong with the EV T18 (especially if you can get it cheap)?
38Hz Fb with not much output down that low.
The falling low end response limits 40 Hz output to about 118 dB with 500 watts, about as much as the speaker will safely take.
Up around 100 Hz, it can do about 10 dB more, more than twice as loud sounding.
If the T18 frequency response and output level suits the music you play, nothing wrong with it, though it takes a lot of EQ to get close to flat 40-100 Hz.
Check the speakers out carefully though, old surrounds may be ripped or ready to rip.
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Hi nuconz!
See EV's Spects and plots for 30W:
http://www.fullcompass.com/common/files/2936-T18 EV specs.pdf
83dBs at 40Hz, 97,5dBs at 50Hz, near 105dBs at 100Hz, and near 110dBs near 150Hz, and than plus 25dBs down near 200Hz;
Look at HD at 30W only;
If we search here at DIY some TH 12 examples and verify that they do the work better than that (near flat), with a fraction of EV's T18 total volume appears to me that I have to let EV's T18 rest in peace.
Regards,
See EV's Spects and plots for 30W:
http://www.fullcompass.com/common/files/2936-T18 EV specs.pdf
83dBs at 40Hz, 97,5dBs at 50Hz, near 105dBs at 100Hz, and near 110dBs near 150Hz, and than plus 25dBs down near 200Hz;
Look at HD at 30W only;
If we search here at DIY some TH 12 examples and verify that they do the work better than that (near flat), with a fraction of EV's T18 total volume appears to me that I have to let EV's T18 rest in peace.
Regards,
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PASC,
I would agree to let the T 18 rest in peace.
Your numbers are incorrect however.
There is a mistake in the EV graph, the top line should read 110, not 120, as the graph lines are in 5 dB increments.
To put it in to perspective, jbel’s Stadium Horn is over twice the volume of the EV T 18 , 692 liters compared to 320 liters for the T 18.
The Stadium Horn is about 102 dB sensitivity, pretty well flat to 40 Hz, it has about 8 dB over a pair of T 18 at 40 Hz, a huge difference.
At around 70 Hz and above, a pair of T 18 actually have a sensitivity advantage over a single Stadium Horn.
Playing music recorded in the pre CD era (when the T 18 came out), the difference between the subs would not be so noticeable, but with music recorded in the last couple decades, the difference is huge.
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