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Directivity of TH115/118

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Steven Gustafson:
Mike keep up the good work.  As one of Doug Jones' former students, I know your company is on the good track.  I'll be purchasing sometime.  Just have to save.

Mike Hedden:
Another point on the measured response of 8 TH15's is the measurement us 90 degrees off axis. The measured response behind the cluster where the typical stage position was closer to -15dB referenced to on axis.

Mike Hedden
Danley Sound Labs, Inc

Franz Francis:
Since I have been referenced and I am the proud owner of twenty-four (24) TH-115 I will share my views of the twenty (20) TH-115 I arrayed for this particular Carnival location and many other outdoor venues where the requirement for high output, musical sounding subwoofer reinforcement calls for.
Like I’ve always noted in the old forum I prefer the TH-115 sound or performance when powered with an amplifier rated at twice the RMS of the driver in the box. I have no scientific data to back this up therefore don’t hold me hostage because of this claim. I started off powering them with the Crown 5000VZ based on its reputation as a legendary subwoofer amplifier.

The Lab Gruppen FP=13,000 (Presently replaced by the FP=14,000) are probably some of the most Versatile professional amplifiers presently manufactured, not only can they deliver full output power but can also be  scaled down to varying lower output levels  through their  VPL dip switches. Back then there was this unscientific claim switching power supply amplifiers was not good for powering subs. I convinced myself I could work around this myth by reducing the output leaving enough power supply headroom to cater for extended low frequency burst.

Coincidentally I was doing component level repairs on one of my 5000VZ in the shop and discovered in the service manual this amplifier is only rated at 1700 watts into four (4) ohms amplifying frequencies below 1Khz. I was way under powering my subs with this amplifier.

My TH-115s are the eight ohm models, each rated at a thousand (1000) watts RMS. Two boxes in parallel on one amplifier channel should be able to take the full voltage of an amplifier capable of doing 4000 watts into four ohms based on Danley’s info and the manufacturer of the loaded TBX100 driver B&C. Although I believe both manufacturer ratings are quite conservative
I decided to AB test them with the higher powered Lab Gruppen configured for full output into eight and four ohm loads per channel. Man the difference was like night and day, it was so much louder, heavier and more controlled with the Lab Gruppen amplifier. I have no scientific data to back up my claim it is just way better with this amplifier. I am hoping to carry out the same test with Powersoft’s K20, this amplifier specs are just as impressive as the Lab Gruppens

As of today I have never turned back, sold most of my 5000VZ and bought more FP+14,000.
On the question of directivity, after listening and measuring various configurations outdoors (I love the outdoors there is no limit as to what one can do with the PA) in the popular left and right configuration, I discovered  when arrayed as mentioned earlier in the thread  there is a huge amount of forward directivity together with a huge reduction of sound from the back of the boxes, it is almost like doing a cardioid setup without having to go through the drawback of having to point speakers facing backwards then applying delay to the front boxes to create it.

Having ten (10) or more TH-115 per side configured this way is an experience one will never forget. Phase aligned with the GEOT there is only a small and I am stressing a small amount of the power alley effect on either side of the middle, when cranked up to concert levels it is almost inaudible or felt and can be ignored.

Front of house for our outdoor deployments located at one hundred and fourty (140) feet back exposes us to blurred vision and a thundering low end which feels like our chest cavity is ready to rip open but very musical.
 Anyone who has experienced our outdoor deployments with twenty (20) and sometimes twenty-four (24) boxes of TH-115s configured this way can never walk away with the same feeling about large scale musical sounding high output subwoofer system capabilities; even diehard touring sound engineers are converted. There was this one guy who was convinced there was some magic going on in the Dolby Lake Controller, I went as far to show him the tunings, high passed at 31Hz  BW24, low passed at 85Hz BW  one parametric EQ of 4Db in the 35-40 Hz area and three out of band parametric, increases the low pass crossover slop and that’s it, well with limiters engaged. :}:}

NEXO’s NEXstrem Load for the GEOT high passes the box at 90 Hz therefore I am forced to low pass the TH-115 in the-85Hz area. I honestly don’t like the tone of the sub as a matter of fact any sub low passed this high, I prefer and believe subs rain king low passed in the 71 Hz and below area. This is where I low pass them when I deploy them with our SH-50 and SH25 boxes and work out very well this way. The TH-115 seem to have a lot of acoustic energy above the 79hz region and needs to be tamed properly but pretty soon I will work around this small issue with the GEOD sub flow with the GEOT in overlap mode. The NXstream load high passes the GEOD sub at 75Hz for overlap mode. I will then be able to low pass the Danley in the 70 Hz and below area.

I will also be increasing my fleet of 24 TH-115 with eight  of their TH-118, the amplifiers have already been ordered for them.

This is my first post on the new forum, since I have not read the fine prints about the rules and regulations I hope I am not offending anyone here by naming several manufacturers in my post, I am not affiliated with any of them. Moderators feel free to delete my post if it disqualifies. Thanks.

Franz Francis   


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