Keystone Sub Using 18, 15, & 12 Inch Speakers

The DSL spec for the TH118 speaks of sensitivity as being 108 dbspl at 1m. If that means 2.83 volts into a 4 ohm load, then I can assume the SPL is still 105 dbspl for 8 ohms. Still great considering the useful lows down to 35hz. 105 db for 1 watt (assuming little compression) might give 138 db for 2000 watts. I notice the website says 137 dbspl max or 143dbspl peak. (The Cerwin Vega TS42 also quotes max SPL of 144 db.)
Does the Keystone give the same average levels of SPL? I am reading that the keystone reaches 130 db. If I add 3 db for max I still only get 133 db.spl. Well these might just be numbers on paper or am I missing something? What do the measured and subjective tests show? Thanks in advance for clarifying.

http://www.danleysoundlabs.com/danley/wp-content/uploads/2012/04/TH-118-spec-sheet.jpg
 
The DSL spec for the TH118 speaks of sensitivity as being 108 dbspl at 1m. If that means 2.83 volts into a 4 ohm load, then I can assume the SPL is still 105 dbspl for 8 ohms.
As far as I know, that spec (105db/1W nominal) is still considered questionable by a lot of people. Far more sensitive than both the keystone and TH18 have been measured as, both of which are very similar.
 
The time/resolution info at the top of the graph on the data sheet lead me to believe the measurement is actually pretty far from anechoic, but then again I'm not a TEF user.

Its definitely NOT anechoic, however it is optimized for the highest frequency resolution. assuming they were 400 feet or so from boundaries, it should be an accurate 2 pi chart, and givin how fine the freq resolution is, we would be able to clearly see any reflections represented in the chart.
 
I only say 400 feet (should have said 459 ft) because that is the distance at which the TEF was configured to "reject reflections" from (can see it on the chart). with a freq resolution of 2, any notches should be clearly evident (granted they have 18 percent smoothing enabled as well).

the only thing I suspect (IF there is anything wrong with the graph, which I honestly dont believe) is improper mic calibration (resulting in a "too high" sensitivity reading).

I just got a TEF 25 last week though, so dont take my word on it... stilllllll learning how to implement it correctly.
 
The DSL spec for the TH118 speaks of sensitivity as being 108 dbspl at 1m. If that means 2.83 volts into a 4 ohm load, then I can assume the SPL is still 105 dbspl for 8 ohms. Still great considering the useful lows down to 35hz. 105 db for 1 watt (assuming little compression) might give 138 db for 2000 watts. I notice the website says 137 dbspl max or 143dbspl peak. (The Cerwin Vega TS42 also quotes max SPL of 144 db.)
1)Does the Keystone give the same average levels of SPL?
2)I am reading that the keystone reaches 130 db. If I add 3 db for max I still only get 133 db.spl. Well these might just be numbers on paper or am I missing something?
3)What do the measured and subjective tests show? Thanks in advance for clarifying.
1) Probably quite similar, if measured the same.
2) Peak response in calculated manufacturer's specs don't consider Xmax, the 130 dB I quoted is at Xmax.
3)Measured response with a "normal" SPL meter verify that the Keystone can do around 130 dB in the LF.
PASC used the same 18 Sound driver in an Xoc TH18 (same size and similar fold to the DSL TH-118) and the Keystone and found the Keystone to be slightly louder and cleaner.

Here is a comparison of a DSL TH118 to an EAW SB1000z:
https://soundforums.net/threads/6793-TH118vsSB1000z

My observations are in post #8.

David Gunness, former designer at EV and EAW, now with Fulcrum Acoustics has explanations of the specs "game" in post #18 on 4/10/14:

https://soundforums.net/threads/9905-Compact-Power-Subs-for-Stick-mains

"OK, here we go. Once more into the breach. The reason I hate this is that in the process of explaining how our industry does specs, it appears that I am justifying practices that I actually don't agree with.

One of the reasons I don't like peak SPL specs is that "SPL", at least in textbooks, is defined as the RMS sound pressure (referenced to 2x10-5 pascals). So theoretically, there is no such thing as "peak SPL". OK, maybe that's too pedantic: we could interpret it as "peak sound pressure, expressed in units of SPL". Let's go with that.

The point is that "Peak SPL" as it is treated in the professional loudspeaker industry, is peak pressure, not "highest reading of an SPL meter" (SPL meters only measure RMS; even if there is a peak hold function, it is the "highest rms reading observed", and that includes the selected averaging time). Anyway, peak pressure is calculated using the peak voltage of the amplifier. With non-powered systems, the assumption is that a user will supply an amplifier with twice the power rating of the loudspeaker, and that the peak voltage of the amplifier is 3 dB higher than that, because amplifiers are rated with sine waves. Hence, the peak pressure should be 6 dB higher than the maximum continuous SPL.

Keep in mind that maximum continuous SPL is a survival rating, not a useability rating. Of course what would be more useful is "maximum useable SPL", but that would be signal dependent and would have to be subjectively determined. So we're stuck with a calculated value that serves only as a point of comparison: "This one's red line is 2 dB higher than this one's red line."

As for the TS215ac, here is the math (with one more significant figure than the whole numbers on the spec sheet):
Equalized Sensitivity: 99.2 dB
Maximum Peak Voltage of the Amplifiers: 150 V
"Peak Power" into 2 ohms (actually two channels driving 4 ohms each): 11,250 W
Peak Power, expressed in decibels: 40.5 dB
99.2 dB + 40.5 dB = 139.7 dB, which rounds to 140 dB"



Back to subjective/measured response, prior to building the Keystones, I got a chance to compare four of my small ported dual twelve cabinets using Lab 12 speakers to eight dual 18 Meyers 650P cabinets.

On a two stage side by side outdoor show I got a chance to compare four of my small ported dual twelve cabinets using Lab 12 speakers to eight dual 18 Meyers 650P cabinets, measurements done on a RTA at the same point equidistant from both sub set ups.

The four 22.5 x 22.5 x 26.5 dual Lab 12” (fB 36 Hz) driven by a pair of Crest CA-9 amplifiers put out 4 dB less at 60 Hz, but 2 dB more at 40 Hz than the eight 650P, using a small fraction of the power, the whole PA was run off two 20 Amp 120 volt circuits. Those four cabinets equal the size of a pair of Keystones.

8)12” cones, 3600 watts, 31 cubic feet of truck space, 400 LBS.
Compared to the eight Meyers 650P :
16) 18” cones, 9920 watts ”burst capability”,140 cubic feet of truck space, 1768 LBS.

A pair of Keystones using the 18SW115-4 driven with the same amplification are louder than the four dual Lab 12, which were louder at 40 Hz than the Meyers 650P, and the Keystones are several dB louder at 60-100 Hz than the four dual Lab 12.

At any rate, if you look at the Meyers 650P specs, you can see a large disparity between "paper" and subjective/objective reality.

Art
 
I have looked at the plans seems a simple build I have built subs before (BFM T24s, Cubo Sub 18) and have 2 sheets of 4X8 BB 13 ply I have a PD 184 new in the box shipped to me 2008, can I use this driver low Qts, will use this for low power sub Djing 100-250 capacity venue weddings indoors so no real high volume needed here. https://www.solen.ca/documents/pdf/precisiondevices/PD184.pdf
Big thanks!
 
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I have a PD 184 new in the box shipped to me 2008, can I use this driver?

Any driver can be used in any box, you can use the Hornresp inputs from post 96 or 130 and enter in the PD 184 parameters to get an idea of the response, and if it will do what you want.

Response should not look too bad, but will have at best -6 dB less output than the BC18SW115.

Art
 
The DSL spec for the TH118 speaks of sensitivity as being 108 dbspl at 1m. If that means 2.83 volts into a 4 ohm load, then I can assume the SPL is still 105 dbspl for 8 ohms.

I believe the 1M SPL rating is based on measurements that were done at 10M.

I also believe that the assumption was made that the SPL would drop off at a specific rate as a mike is moved from 1M to 10M away.

If that assumption is pessimistic, then the calculated performance @1M would be optimistic :).
 
1) Probably quite similar, if measured the same.
I was hoping by now there would be some definite measurements available.

2) Peak response in calculated manufacturer's specs don't consider Xmax, the 130 dB I quoted is at Xmax.

With what wattage was the speaker being fed ? If it was with 2,500 watts, then this appears to work back to less than 97 db for 1 watt/1m.

Here is a comparison of a DSL TH118 to an EAW SB1000z:
https://soundforums.net/threads/6793-TH118vsSB1000z
.

This is great stuff. I have heard the SB1000s so I can almost imagine from the chart how the TH118 will sound. A comparison like this between a DSL TH118 and a Keystone would be extremely useful to me. I have heard the DSL TH115 s, nice and punchy and thick at the same time.

David Gunness, former designer at EV and EAW, now with Fulcrum Acoustics has explanations of the specs "game" in post #18 on 4/10/14:

https://soundforums.net/threads/9905-Compact-Power-Subs-for-Stick-mains
. Great stuff.


The four 22.5 x 22.5 x 26.5 dual Lab 12” (fB 36 Hz) driven by a pair of Crest CA-9 amplifiers put out 4 dB less at 60 Hz, but 2 dB more at 40 Hz than the eight 650P, using a small fraction of the power, the whole PA was run off two 20 Amp 120 volt circuits.
.

This is almost unbelievable when rated against Meyers reputation for bass, but I guess it is what it is.

Which would you say gives the best punch around 45Hz to 60 Hz, a Keystone, a Th18 or an Othorn?
 
scientific, there is most definitely a direct comparison between the keystone and the th18 in this thread. with measurements.

they are very similar in response shape and sensitivity. subjective analysis by member PASC states that he enjoyed his keystone more than his XOC1 TH18 (which, is not exactly a danley th118), due to "better cone control" (again, a subjective analysis)
 
1)I was hoping by now there would be some definite measurements available.
2)With what wattage was the speaker being fed ? If it was with 2,500 watts, then this appears to work back to less than 97 db for 1 watt/1m.
3) A comparison like this between a DSL TH118 and a Keystone would be extremely useful to me.
4)This is almost unbelievable when rated against Meyers reputation for bass, but I guess it is what it is.
5)Which would you say gives the best punch around 45Hz to 60 Hz, a Keystone, a Th18 or an Othorn?
1) I have never seen a DSL TH118 in New Mexico, so have not been able to compare the two. I have sold my Keystone/Paraline system to a sound company in Colorado, so no longer could make a direct comparison.
2) According to Hornresp, 82volts (about 1681 watts) results in 15mm excursion with the BC18SW115-4 in the Keystone. That seem pretty close to PASC's and my measured response using "normal" SPL meters.
3) DIY ;^).
4) Frankly, the side by side comparison was a surprise to me, but it was real world.
5) Having only looked at measurements of Th18 or an Othorn, I'd expect them to be similar, with the Keystone having a bit (2 dB, IIRC) more output than the TH18 according to PASC. The Othorn goes lower, which could translate to sounding less "punchy".

Art
 
scientific, there is most definitely a direct comparison between the keystone and the th18 in this thread. with measurements.

they are very similar in response shape and sensitivity. subjective analysis by member PASC states that he enjoyed his keystone more than his XOC1 TH18 (which, is not exactly a danley th118), due to "better cone control" (again, a subjective analysis)

The driver is mounted vertically in the KS and horizontally in the TH18, in their normal config. I wonder if that has anything to do with it?
 
The driver is mounted vertically in the KS and horizontally in the TH18, in their normal config. I wonder if that has anything to do with it?
Brian,

I have rotated subs so the cones are vertical or horizontal on many different gigs, no difference in output before breakup occurs.

Gravity will eventually take it's toll on horizontal cones and cause them to sag, but "cone control" is determined by acoustical loading.

Art
 
Brian,
I have rotated subs so the cones are vertical or horizontal on many different gigs, no difference in output before breakup occurs.

In the case of the KS, wouldn't that result in the mouth facing upwards?


Gravity will eventually take it's toll on horizontal cones and cause them to sag, but "cone control" is determined by acoustical loading.

Good point. How different though is the loading on the driver between the KS and the TH18?

There's another possibility. Perhaps it might be due to panel flex colouring the sound. My POC3 uses the same fold at the TH18. I may be imagining things, but I've noticed a difference when it's placed on its side compared to when it's upright. I thought that might have something to do with the bottom panel not being against the ground when the sub is used on its side (of all the panels, the side panels flex / vibrate the least) . I've never tried to quantify it by measurements though. I'll try to do that this weekend.