I don't know the story on picture #26.

http://www.audioroundtable.com/ArraySpeakers/messages/1281.html

AS such, there's virtually NO cross driver interference (limited only to horizontal plane), the planars are FAST, and the imaging is spectacular.

total cost per speaker was ~$700 US.

This is an exception. Those drivers new cost about $1500 a pair,
therefore I can find something better for that budget. I wouldn't
spend that kind of money for RD75, I'd want more performance for
that kind of coin.

And why do you haved to have a 2 way crossing at 350hz?

I don't agree with spending the amount of money you are talking about, and compromising the array in the way you have done. I mean $1500 for the tweeters?

I don't understand.

Email me and we'll talk about it off-line.

marlboro

Still, sensitivity and more importantly max SPL will go up considerably with close to 50 drivers, and 90 looks about right for 2.83v/1m for 45 of them. This may work, but it will require some quite serious amplification - reacing peak at 20w/driver means 900w dissipated for an SPL of 97db at 1 meter. This is still a bit on the low side, and 11db lower than the RD75 at peak power (400w).

I am not writing this of, but dynamic headroom is important. And based on these numbers the savings from going with the cheaper drivers may not outweigh the costs in terms of less headroom and much more work in building the things...

Interesting setup! Could I ask if you have tested the RD75's to see how far they can go upwards and downwards? I see that you got some advise from ThomasW to cross relatively high to the HDS182's, but there are quite a few reports of good results down below 300. Any experience with this?

Also, have you tried EQing the RD75's to get them (closer to) flat up to 20k?

700/speaker is not bad BTW - I have a feeling I am looking at the wrong side of 2k per speaker. Still, should be worth it!

The 90db sensitivity rating for 1w/1m with 45 drivers is a bit misleading. This is a measure for the SPL with 1w energy dissipated for each driver. The SPL for 1w total energy dissipation does not change, that remains at 74db/1m (according to Zaph), only it is now generated by 45 drivers burning off 1/45w each. The real gain is in lower distortion and more headroom. It is more meaningful (although not very precise due to impedance variation over frequency) to use the SPL @ 2.83v/1m measure here, as 2.83v across all 45 drivers will produce around 90db/1m.

Anyway, you are right in that my number was too low, it should be around 103,5 max SPL with 20w/driver peak. That is actually less than 5db off the RD75, so this may not be so bad. More thinking required!

When multiple drivers are used, the sound waves emanating from them will combine to create a composite sound wave that is louder. BassBox Pro assumes that the drivers are all the same kind and, in most cases, that they are driven with identical signals so that their sound waves will usually sum coherently. This means that the net sound level will increase 6 dB with every doubling of drivers.

However, there may be occasions when the sound waves do not add coherently and the “Drivers do NOT add coherently” option should be turned on. In these cases the net sound level will increase only 3 dB for every doubling of drivers. The following list describes situations when coherent additions will not happen. Turn on the “Drivers do NOT add coherently” option for these situations:

• The drivers will not sum coherently if they are wired separately and are driven with different signals. For example, two woofers are mounted in a common cabinet but one is driven from a left stereo signal and the other is driven from a right stereo channel.
• The drivers will not sum coherently if they are mounted too far apart. Their center-to-center spacing should be no greater than one quarter (¼) wavelength for the frequencies in their passband. This is usually not a problem for subwoofers because they are driven only with low-frequencies having long wavelengths. For example, many subwoofers use a crossover frequency of 100 Hz or less—the wavelength of 100 Hz is 136 inches (345 cm). As long as the drivers reproduce frequencies that are not higher than 100 Hz then the drivers in the subwoofer can be mounted as far as 34 inches (86 cm) apart because this is one quarter of 136 inches.

I did try running them swept up to ~16K or so... pretty much followed the response found online on numerous forums... hence the panasonic supertweeter... down lower I didn't need as the peerless midwoofs are smooth up to > 1Khz and have plenty of wallop (>108dB @ 15 feet listening position)...

rather than pushing the RD75's w/eq, I added the ATC neoplanar 25's I found on ebay for ~$175 ea. they're good past 20Khz, @ ~92 - 93 db/w.. handle 150W RMS...had to pad them down abit to match the RD75's.

I would have probably built using only the neoplanars had I found them first, but this setup sounds incredible as is.. so I'm a happy camper... keep your eyes out for these planars... not withstanding the nay-sayers... I can never go back to pisstonic cone speakers (other than bass and subs) after building and hearing these line source dipoles... the imaging is staggeringly rock solid and lifelike...