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[Bob Leonard]

I use a 4050HD for each pair of backline 718s and 725s, and a 3602 for each pair of 725s used for vocals.

[Randall Hyde]

For DJ playback and occasional live sound gigs.  Right now I have two 725 tops and two 728 subs running off of one Crest 10004 (two 8001 amps in one chassis).  It's rated for 1200/rms into 4 channels, so each cabinet sees 1200 watts RMS.  It's plenty loud, but I see people here talking about hitting the subs with 3000+ watts per cabinet.  I realize they're rated for 3200 program, but I just can't imagine putting 2000 watts into EACH driver.  Will they even survive?

Currently, I run four SRX 728s off two ITech 8000 amps. That seems to be a very good match for the subs (1600/3200/6400). I use a DR260 as cross-over (yeah, yeah, why not use the amp's DSP? I know) and it provides appropriate limiting.  Kicks chest in out to about 100'-150' real easy. Nice bass thereafter.

I also run four SRX 725s off two ITech 8000 amps. A bit much for these speakers. I'm going to be looking for some used ITech 6000 amps for the 725 cabs real soon now and use all four IT8K amps for subs (I have six 728s cabs, but no power for two of them yet; I'll probably buy two more so I can run a cardiod subwoofer array).

With 4 SRX 725 and 4 SRX 728s cabs, I've been doing crowds of 2,000 with good SPL near the back of the venue. By adding a second set of four SRX 725 cabs as delay stacks, I've gotten as high as 4,000 people (though the sound quality sucks with delay stacks). Don't put subs in the delay stacks as (1) I don't have the amps, (2) I don't have enough subs to do subs at the delay stack position (*need* cardiod arrays there).

For DJ'ing, that's a pretty good rig you have there. Depending on your max audience size, who cares if you have the biggest and baddest amps? Despite popular opinion, you don't damage the speakers by underpowering them, they just won't get as loud as they are capable of. If you're happy with the sound in the back of the venues you work at, don't sweat it.
cheers,
Randy Hyde

[Jonathan Betts]

Yep - they are rated at 1600 cont.  I don't run them near that limit continuously (more like 3db below that).  Though, the subs really shine when the performance calls for it.  Compressors help keep things under control. 

Running the PLX in stereo would not fit well for those speakers.  The amp's max power in that mode is less than what the speaker can handle continuously; this would probably result in the amp running close to full power (lower headroom) more often while at the same time, not being able to experience what the 728 can provide.

If you get an opportunity, try running your 718's with 1600 watts (not continuously!), but to provide 3-6db of headroom; I think you'll be surprised how well the cabinets can take the power and much more full the system will sound.

I have always been warned by many whom have more experience than me that power compression takes over near 700w with these cabinets. Any more power is just producing heat not volume. This is coming from people who recone these speakers on a regular basis.

[Scott Carneval]

I think I'll stick with my 1200 watts per cab.  Like the saying goes "If it ain't broke, don't fix it"

[Robert Weston]

I have always been warned by many whom have more experience than me that power compression takes over near 700w with these cabinets. Any more power is just producing heat not volume. This is coming from people who recone these speakers on a regular basis.

Burning speakers --- sounds like there's probably some (more like a lot) inexperienced people behind the board of many systems.  For most, I think they see watts and they think they can run their amps and speakers to the maximum of whatever the equipment says.  I grew up listening to live sound that sounded like shit.  But when I did hear a good sounding event, I talked to the FOH guy every time.  Learned a lot.  Unfortunately, there's still a lot of people running systems incorrectly.

[Jonathan Betts]

I use a 4050HD for each pair of backline 718s and 725s, and a 3602 for each pair of 725s used for vocals.

I also have a 4050 HD and have run my 4 718's in stereo with this amp. It sounds amazing. I love this amp and have found a permanent home for it in one  of my local venues. It will be running 2 712's and 2 718's. Perfect for the 200 person club.

[Robert Weston]

I think I'll stick with my 1200 watts per cab.  Like the saying goes "If it ain't broke, don't fix it"

Yeah - if it works for you, no sense in changing!

[Robert Weston]

Speaking of power...

From JBL's website:

"Ideally you should pick an amplifier that can deliver power equal to twice the speaker's continuous IEC power rating. This means that a speaker with a "nominal impedance" of 8 ohms and a continuous IEC power rating of 350 watts will require an amplifier that can produce 700 watts into an 8 ohm load. For a stereo pair of speakers, the amplifier should be rated at 700 watts per channel into 8 ohms."

I knew I saw this somewhere before... 

[g'bye, Dick Rees]

Speaking of power....

[Bob Leonard]

Speaking of power...

From JBL's website:

"Ideally you should pick an amplifier that can deliver power equal to twice the speaker's continuous IEC power rating. This means that a speaker with a "nominal impedance" of 8 ohms and a continuous IEC power rating of 350 watts will require an amplifier that can produce 700 watts into an 8 ohm load. For a stereo pair of speakers, the amplifier should be rated at 700 watts per channel into 8 ohms."

I knew I saw this somewhere before...

You have, in about 1000 replies to people who are always asking the question. It's a rule of thumb that's been in use since the 60's. But like everything else, it depends on .........

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