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[Silas Pradetto]

Elliot Thompson wrote on Wed, 05 August 2009 09:31

The RCF Chris suggested would be as efficient as the Electrovoice EVM 15B Series II with a similar frequency response. It is a good replacement for the driver you are currently using. What you lose in efficiency (1 - 2 dB less) you will gain with more power handling. A 4-ohm version will not be louder than an 8-ohm version. The only difference is where you stand on amplification. If your amplifiers deliver 1000-1300 watts @ 8 ohms, it would be safer to use the 8-ohm version  @ 1000-1300 watts than, a 4-ohm version that will see 2000-2500 watts. Using 4-ohm drivers only benefit those who don't have enough amplification to drive the loudspeaker at the recommended wattage by the manufacture at 8 ohms. Bear in mind, these drivers are Mid-Bass loudspeakers not woofers. There will still be a large reduction below 75 Hertz in terms of output. However excursion headroom will be more than the stock driver sitting in the horn at the moment. You should not have any problems attaining frequencies ranging from baritone male vocals to tenor female vocals with this driver. Add the horn in the equation and, you will have a very High SPL horn-loaded cabinet under today’s standard.   The difference in tone amongst the old driver & RCF is merely adjusting your parametric. If the box begins to ring when feeding it 600+ watts at certain frequencies, just dampen the flares with any type of dense fabric material inside the box. Best Regards,

Excellent. I don't know if I've described the speaker or if you're familiar with the box, but it's the old Community RS880. Here's a link to the newer version: http://www.directproaudio.com/product.cfm?directid=56190 which is also discontinued. The only reason I'd like to keep impedance the same is because it has a passive-only crossover. I can modify it to make it biamp if I have to but I'd rather not. The dual 15 passband operates from 100Hz to something like 400Hz, so there will not be any strong bass going toward it. Community even told me that going below 100Hz blows the top 15 every time because the ports are above the top driver only and there is a problem with unequal air pressure.

I'll look into sourcing these RCF drivers and see how they do.

[Art Welter]

Silas Pradetto wrote on Wed, 05 August 2009 09:12

The only reason I'd like to keep impedance the same is because it has a passive-only crossover.

Good luck finding 2.29 ohm speakers.

[Silas Pradetto]

Art Welter wrote on Wed, 05 August 2009 14:11

Silas Pradetto wrote on Wed, 05 August 2009 09:12 The only reason I'd like to keep impedance the same is because it has a passive-only crossover. Good luck finding 2.29 ohm speakers.

That's DC resistance Art, I don't think that's out of the question for a 4 ohm "nominal impedance" woofer?

[Elliot Thompson]

Thanks for the photo for I had no idea what the enclosure resembled.

Two 8-ohm drivers wired parallel will bring forth a four ohm nominal load so, you should have no issues using two 8-ohm drivers with your passive crossover… Providing the passive crossover can withstand the amount of wattage you are going to feed the loudspeakers.

If they are not strong enough the choke will burn and/or the capacitors will explode. Since your cabinets are older than the photo you offered, the power handling could be lower as well. I would imagine Community will be able to tell you how stout the passive crossover is under the wattage you plan on feeding the cabinet.

Even if you feed the cabinet 1200 watts it will be very loud from 250 Hz on up considering it has a large mouth. It should sound really good on percussion instruments.

Best Regards,

[Art Welter]

Silas Pradetto wrote on Wed, 05 August 2009 12:14

Art Welter wrote on Wed, 05 August 2009 14:11 Silas Pradetto wrote on Wed, 05 August 2009 09:12 The only reason I'd like to keep impedance the same is because it has a passive-only crossover. Good luck finding 2.29 ohm speakers. That's DC resistance Art, I don't think that's out of the question for a 4 ohm "nominal impedance" woofer?

The only 4 ohm nominal speaker I happen to see in the Eminence line, the basslight C2515 (weighs only 5.7 pounds) has re of 3.72 ohms.

Not very close.

The RS880 uses a lower than normal DC resistance as the horn loading raises the nominal impedance.

Anyway, the re factor is not the only parameter that will mess with the passive crossover frequency and slope.

If the speakers are all intact, and you want to stay passive without going down the rebuild the passive crossover rabbit hole, I’d just put a new coat of latex around the surrounds and call it a day.
You are only going to save 10% cabinet weight and probably will loose efficiency with just about any modern replacement. Go with higher power lower efficiency speakers, and the passive crossovers may smoke, and not sound good in the process.

[Silas Pradetto]

Art Welter wrote on Wed, 05 August 2009 14:48

Silas Pradetto wrote on Wed, 05 August 2009 12:14 Art Welter wrote on Wed, 05 August 2009 14:11 Silas Pradetto wrote on Wed, 05 August 2009 09:12 The only reason I'd like to keep impedance the same is because it has a passive-only crossover. Good luck finding 2.29 ohm speakers. That's DC resistance Art, I don't think that's out of the question for a 4 ohm "nominal impedance" woofer? The only 4 ohm nominal speaker I happen to see in the Eminence line, the basslight C2515 (weighs only 5.7 pounds) has re of 3.72 ohms. Not very close. The RS880 uses a lower than normal DC resistance as the horn loading raises the nominal impedance. Anyway, the re factor is not the only parameter that will mess with the passive crossover frequency and slope. If the speakers are all intact, and you want to stay passive without going down the rebuild the passive crossover rabbit hole, I’d just put a new coat of latex around the surrounds and call it a day. You are only going to save 10% cabinet weight and probably will loose efficiency with just about any modern replacement. Go with higher power lower efficiency speakers, and the passive crossovers may smoke, and not sound good in the process.

I absolutely agree. I will be getting the 880s in early next week, and I'll check out the sound and the drivers. There is a chance I'll drop in the SLS980 crossovers (these allow biamping) and use new drivers, but if all is well as they sit then I'll just keep them that way. They're only for sidefills and DJ fills anyway; I'll probably never use them as a main PA.

[Rory Buszka]

You can make your RS880's into a biampable speaker easily: add a panel-mount Speakon and a toggle switch that switches the LF end of the crossover in and out.

Be ready to use a lot of processing with these speakers. They were originally made to work with active equalization provided by a system processor in a scheme similar to the passive Meyer Ultraseries, so they eschewed purely resistive components in the crossover network. Really, you ought to be biamping these as a rule, not just for special occasions, and some sort of system processing is a prerequesite - otherwise the M200 will run away from the other passbands. The RS and SLS speakers were designed to be far more efficient through the midband than in the other passbands - since that's where much of the music is, and a speaker's ability to 'throw' depends on an efficient, undistorted midrange. This ensures that at high levels, neither the LF or HF sections run away from the midrange.

The Community M200 is an excellent midrange driver. Ordinary 2" compression drivers are horribly distorted through the midrange, primarily because of the compromises required in phase plug design for a driver that produces usable treble energy. By contrast, the M200s have a very large metalized Mylar diaphragm (~ 4") and a I don't recommend ever replacing the M200s.