I always liked the quality of sound in IMAX, even it may have been too loud for me, since I have good hearing and like to keep it.
IMAX sounds way better than normal Regal Cinemas with their distorting over the top sound.
Interested what set of drivers are used in IMAX.
IMAX sounds way better than normal Regal Cinemas with their distorting over the top sound.
Interested what set of drivers are used in IMAX.
Drivers used in the IMAX PPS system??
EarlK
Jay Mitchell over at LHF said:I am the designer of the IMAX PPS (Proportional Point Source) theater loudspeakers and associated active crossovers. I came across this thread and joined the forum to provide correct information about these speakers.
Originally Posted by Woofer
Two more pics of the back of the boxes showing the TAD (with the 8" removed), and crossover.
The components on the PC board are for DC protection only. The crossovers were entirely active and were integral with the power amplifiers.
The polarity "reversal" on the 8" midrange driver - which only applies to the larger version of the speaker with 4x12 LF transducers - is to account for its physical reversal: it is mounted with its magnet forward. The same transducer in the smaller version, which employed 2 12" LF transducers firing through slots - was mounted and wired conventionally.
With the exception of the TAD 2001 HF driver, the transducers in the PPS speaker were produced for Sonics on an OEM basis by Eminence. Other than the HF driver, which was TAD only, my specifications for the design included approved transducers from three manufacturers: JBL, Cetec Gauss, and Eminence. JBL discontinued the 12" drivers in the LF section and Sonics encountered some issues with the JBL 8" driver called out for the midrange. Mark IV Audio acquired the Cetec Group, moved transducer manufacturing to an EV plant in Tennessee, and immediately began using different parts to make Gauss transducers. At that point, the only manufacturer whose parts were compliant with the specification was Eminence, so Sonics went with them. To my knowledge, those components were unchanged for the production life of the design. IMAX dissolved Sonics ca. 2002 (+/- a year or two), at which time production of the PPS system ceased. At that time, sufficient inventory of those systems had been amassed to supply new theaters for the next 3-4 years.
EarlK
Yes, have the foam.
I have Jay's book ( the designer), but no helpful information.
I have also written to Jay, but he hasn't replied.
I have Jay's book ( the designer), but no helpful information.
I have also written to Jay, but he hasn't replied.
I have all the original drivers.
Would just like to know the details of the crossovers.
The 400-7kHz range was never suggested by Jay Mitchell, the designer of the IMAX PPS.
He mentions in his 2013 Lansing Heritage posts the active crossovers were integral with the power amps used.
To duplicate what Jay designed would require duplicating the transfer function of the original crossover in whatever DSP you are using.
As a guess, Jay's filters may be "unique" in using different orders to time/phase align without using digital delay, while also providing corrective equalization to raise the falling upper response of the proportional point source horns.
Since finding transfer function is unlikely, I'd suggest starting with LR24 at 400 and 1600Hz, with PEQ flattening far field on axis response within each pass band. The 8" mid horn may require delay to line up with the HF horn. The 12" may also require a bit of time offset too.
Art
Hi Art
Many thanks for the response.
Yes, we know all that. Even though the people helping me design the crossovers are very knowledgeable, it would still be nice to know what he did.
We have the flexibility to implement virtually any type of crossover, any slope, eq, etc.
Although we are very happy with the outcome, it would be nice, to have the choice of using his implementation.
A very important factor in all this, is we will not be using them in a situation they were designed for.
It is highly probable, that if he were designing them for domestic use, much smaller spaces, closer listening position, the crossovers would different from Imax use.
Thanks again
Many thanks for the response.
Yes, we know all that. Even though the people helping me design the crossovers are very knowledgeable, it would still be nice to know what he did.
We have the flexibility to implement virtually any type of crossover, any slope, eq, etc.
Although we are very happy with the outcome, it would be nice, to have the choice of using his implementation.
A very important factor in all this, is we will not be using them in a situation they were designed for.
It is highly probable, that if he were designing them for domestic use, much smaller spaces, closer listening position, the crossovers would different from Imax use.
Thanks again
The asymmetrical downward directivity of the PPS horns were designed to accommodate the steep rake, usual front to back distance and absorptive quality of large scale IMAX seating in conjunction with the high frequency roll-off from the projection screen in front of them.
It is highly probable a domestic use situation won't match the design criteria for the loudspeaker or crossover as originally designed 😉 .
I have a set of these monsters I'm building into a rediculous mega theater above my office for my kids secret hideout lair. I sell and trade audio and speakers so it's costing me next to nothing but probably will be 50K+ worth of gear if it was purchased new. I'll be running them triamped and using a DBX driverack to set them up. First gonna give the auto-eq a run on them and see how well it will do. Probably going to put some FaitalPro mids in them instead of the originals. Also most likely going to load a Faital HF10AK for the HF as I sold off the TADS they come with the more than cover the original cost of the cabs. We shall see how it comes out. The room is in mid construction right now. I just came here to look up any info people may have on them but...
I am using the Faitals. They are good, but I still want to hear them with the TAD's.
Mine were blown, so have been looking for affordable diaphrams. Hard to find.
I am using a Najda for the xover, and it is brilliant.
Good luck.
Mine were blown, so have been looking for affordable diaphrams. Hard to find.
I am using a Najda for the xover, and it is brilliant.
Good luck.
There is nothing wrong with the original drivers. No changes needed. I have been in touch with Emminence, and even they recommend keeping the original drivers.
They don't currently make any current drivers that work as a direct replacement.
I have the subs as well, and they make a hell of a system.
They don't currently make any current drivers that work as a direct replacement.
I have the subs as well, and they make a hell of a system.
I've heard this system before it was removed the the Science museum IMAX with the film Dunkirk, its by far the best cinema sound I have heard. The gunfire was a scary.
The amplifiers used are Bryston amplifiers with custom input boards that do the crossovers a freind has a load of them. Thye are quite complex for an anolog crossover including features like time alignment. These will need re-doing for domestic use anyway so I would go with DSP.
The amplifiers used are Bryston amplifiers with custom input boards that do the crossovers a freind has a load of them. Thye are quite complex for an anolog crossover including features like time alignment. These will need re-doing for domestic use anyway so I would go with DSP.