I will try them in the TH18 design, but I will also build a modified version of it, 45*32*22.5 inches to get it flat to 33 hz instead of 38. With that driver i think I can keep the same SPL as with the TH18 design but I will not have to worry for the excursion. It can safely be used with 21 mm excursion protection and continuously getting over 15 mm without any issues.
Then I will build a reflex sub with the same form function and external dimensions as the PK Gravity 218 which is using the same drivers and the IPal amp to see how they compare.
The KS28 and the LA12 X both received reviews in the Production Partner Magazine , with enough measurements to know exactly what and how they will do in the field. I heard it and played with it and compared it with some Outline Sub218 and DBS18-2 which are using the TBX100, against JBL VTX G28 and tested it against the E219 from Adamson in the same day . The results were interesting. The Outline had the highest tuning frequency, at 37 Hz. All the others had it at 29-31 hz so the sound was very different on them. The JBL had the smoothest less punchy sound of all of them. Deep ,yes!! But not gut crunching and not that loud before flutter.
The Adamson was the meanest and loudest, clearest and had more impact even than the Outlines . But the KS28 was best all-round. It could sustain a drop for long seconds before limiting, the sound was crisp and there was no port noise even when pushed deep into clip. That is the best reflex sub I have ever heard.
The SB28 is not like that. The motor force is not as high as it is on the B&C or eighteensound drivers and the response is low shelved under 60 Hz. That's why they need +11 dB of eq to make them sound flat. This equipment adds a lot of group delay and it lacks punch. I compared a set of 4 of them against 6 Funktion1 F218 last month and even though they were almost as loud and went way deeper, they weren't very engaging. The LA8 amp is good and clean with strong sustained power, but cannot sustain a lot of current over time so the 3.1 Ohms at Fb is engaging the limiters quicker than it is in the next 2 octaves so when pushed hard, the sound changes from a deep strong bass and rumble to a more conventional enclosure, but without the port chuffing.
The sound of the TH18 is better than the one in all of the others. The group delay is very low , by design.if you have a strong amp, stable and with short thick cables, the damping is better because there is no.enclosure to store the energy.
Also the impedance minimum is right where the maximum occurs on most reflex designs so the excursion to reproduce a 50 hz techno beat is minimum in this design compared to max on the reflex. This translates in a different sound signature . another thing, because the radiation surface is way smaller in this TH than those BR, if you are standing closer than 2 meters, the kick is better felt and it appears louder , but not so much over that distance where the radiating surface tend not to count as much.
The particle velocity of the air is increasing in a stable manner as you go lower in frequency and all the sound radiates from the same point in space. This is why they also couple better together and the high order harmonics are diminished
All in all, If I had the money for all the subs and amps I need, I would buy the KS28 with LA12X instead of the TH118 with Linea, just from a business point of view. That's because they would bring me more shows just from riders acceptance and I am sure I wouldn't be asking for more sub and I wouldn't miss anything from the deepest depths to the meanest kicks if I could afford 10-20 of them.
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Yes that would be the best solution but not the most cost effective. It won't be using all the potential of that amp so a version with 21Ipal would be better, tuned at the same frequency, around 32-34 hz low corner, but a bit bigger than the Othorn. Here the choice between a FLH and a TH starts to be taken into consideration so sticking with the original plan of making a slightly larger 18 TH-Ipal.
This is why I wanna see if the clone can be stable enough on that impedance. Also it will be used with K8-20 amps from Powersoft. 2 of them in series on a K20 will be pretty interesting.
Wow, that's almost exactly the dimensions I went with for my POC4 build. The POC4 was slightly less high though, at 40" external. I was able to achieve a ~33 Hz Fb with it, but measured response was down about 6dB at that point. I'm curious to see what fold you came up with.
Playing with the driver on a Crown XLS2002 at FS to see how much the coil can travelTapatalk Cloud - Downlaoad File VID_20170918_140919.mp4Tapatalk Cloud - Downlaoad File VID_20170918_140906.mp4
Hello everyone, I did some tests between the TH18 vs L-ACOUSTICS SB28 , 2 vs 2.
In the blue measurement one can see the response of the 2 TH18 with crossover and EQ and all pass filters to match their impedance trace and coupled to the SB28 .
Yellow curve there's the SB28 raw response and red is processed on the LA8. They add 11.5 dB @34 HZ 0.7 Q
Look at that measurements of something!
A suggestion. Next time you post measurements cut your scale back a bit to zoom in on the bandwidth of interest. No need to show all of the way down to 20 or 30dB SPL. Anything that is 30 or 40dB below the main bandwidth is of little consequence anyway. If the measured output is around 110dB there is no need to have the graph go any lower than 60 or 70dB or so. It will make the graphs uglier though. Good job.
You mentioned that the vented cab was a bit louder than the TH. How did you determine this? What test signal? Was the amplifier itself a limiting factor?
Thanks,
RCF LF18X401 TH MK2 with Side Baffle Adaptation
New TH build nearly complete.
Tuned for 35Hz with an RCF LF18X401 in each, side baffle semi-keystone cutout (mainly for rear rejection purposes) and a removable top to tune using quarter-wave tubes, Helmholtz resonators and velocity or pressure-gradient damping.
They're rough around the edges but they're prototypes.
Hopefully my links work
New TH build nearly complete.
Tuned for 35Hz with an RCF LF18X401 in each, side baffle semi-keystone cutout (mainly for rear rejection purposes) and a removable top to tune using quarter-wave tubes, Helmholtz resonators and velocity or pressure-gradient damping.
They're rough around the edges but they're prototypes.
Hopefully my links work
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Sorry, I uploaded using google drive. You have to right click and open in new tab to view. I still havent got the hang of it
Yeah kind of. Different expansion rate to the Danleys. I'd be lying if I said I didn't take the idea for the mass loading caused by the driver plate overlap from the Danleys.
Yeah same principal as those lambda horns. Just trying to direct more energy forwards.
These are basically just a test bed for some tuning ideas i have inside the horn.
That sloping panel at the bottom of the enclosure - with it as shown, there's the possibility of it getting pushed by the weight of the TH in if you mount any wheels there and use them to move the TH around.
If anyone is interested, In my first prototypes I drilled bolt holes all the way through and attched with teenuts. At high pressure levels you could hear air hissing through the bolt holes. I tried using rubber washers but I could no longer get the tension on the bolts required to prevent a gap forming between the driver/mounting plate interface. The double mounting plate not only provides a seal for the back of the bolts but also more rigged mounting points.