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Efficient Method of Powering (2) Carvin LS1503's?

Zooberwerx

Zooberwerx

Gold Supporting Member
Dec 21, 2002
23,324
28,126
68
Virginia Beach, VA
#1
Okay, get out your sliderules! I'm reconfiguring the rack and would like to re-assign the existing QSC RMX "lead sleds" to get the most out of our modest enclosures. Note: all enclosures are passive and there is no shortage of crossovers, cables, etc. Here's what's available:

(2) Carvin LS1503's

(2) Low-end Yorkville 18" subs daisy-chained together to create a single 4 ohm enclosure. The drivers are aftermarket so I'm not sure what the power rating is. I haven't torn them to tatters so all must be well.

(2) QSC RMX 1450's

(2) QSC RMX 2450's

Fire away and please include the rationale supporting your suggestion(s). Thanks!

Riis
 
#2
With what you have provided for info and what the specs. show on line....

(1) RMX2450 powering (1) Carvin LS1503 per channel.
(1) RMX2450 powering (1) Yorkville sub per channel.

Sell or use the RMX1450's to power monitors.
The 1503 Carvin speakers are only rated 400w continuous, the RMX2450 is 450w @ 8ohms per channel....pretty perfect matchup IMO.

With no info on the sub I can only imagine the 18" driver is rated 250-400w @ 8ohms....so again, the 2450 is properly sized to power these at 1-per channel.
 
#3
Vinny D's recommendation is good. It will allow you to run stereo main's if you wanted to.
I would probably run a 2450 bridged on the two bass cabs, but I would put a limiter on the system, and set your gain structure up so you don't fry the subs again.
Wes
 
#4
Vinny D said:
With what you have provided for info and what the specs. show on line....

(1) RMX2450 powering (1) Carvin LS1503 per channel.
(1) RMX2450 powering (1) Yorkville sub per channel.

Sell or use the RMX1450's to power monitors.
The 1503 Carvin speakers are only rated 400w continuous, the RMX2450 is 450w @ 8ohms per channel....pretty perfect matchup IMO.

With no info on the sub I can only imagine the 18" driver is rated 250-400w @ 8ohms....so again, the 2450 is properly sized to power these at 1-per channel.
Click to expand...

Pretty much what I was thinking. I've been running the subs daisy-chained with a 1450 in bridged mono. I really need to pull the drivers and verify specs!

Edit: I am using the DRPA limiters on all channels.

Riis
 
#6
uhdinator said:
Ls1503 spec
[Invalid or Expired Link Removed]

One 2450 bridged to run tops in mono, carvin recommends 600-1200. Peak is 1600. 2450 in stereo mode is only getting you about 500 per cab.

Subs? Who knows
Click to expand...

I have run both of the aforementioned 1450's in bridged mono, one for each LS1503, which does produce ~900 watts per enclosure. One amp per side...makes for a heavy PA rig!

The single 2450 in bridged mono with enclosures daisy-chained is an option. Any limitations or words of caution?

Edit: Actually, the Carvin DCM2000L, which has similar specs to the 2450, is the recommended / included amp with the LS1503 PA package.

Riis
 
#7
You can't run stereo mains, which may or may not be a concern for you.
We throw a lot of power to our mains (QSC 3402 on 4 Yamaha club series 12x2s), even though they don't advertise that kind of power handing. I like having the power on tap, but you better set your limiters, or know the limitations of your speakers. Set steep crossover slopes, keep the harshness out of the horns.

Regardless, I'd haul around two 2450's, and start off in stereo for the mains. If you feel like you are running out of headroom, then bridge it. Nothing wrong with having too much power, but do it safely.
Wes
 
#8
uhdinator said:
Ls1503 spec
[Invalid or Expired Link Removed]

One 2450 bridged to run tops in mono, carvin recommends 600-1200. Peak is 1600. 2450 in stereo mode is only getting you about 500 per cab.

Subs? Who knows
Click to expand...


This is the only spec. that ever matters: Full Range 400w continuous

Nothing is stopping you from using a much larger amplifier then needed....but the LS1503 is only a 400 watt speaker.
 
#9
Vinny D said:
This is the only spec. that ever matters: Full Range 400w continuous
Nothing is stopping you from using a much larger amplifier then needed....but the LS1503 is only a 400 watt speaker.
Click to expand...

Right... but that says nothing about the amplifier power you need.
A 400w "continuous" speaker will probably need a ~1600w amp on it to receive anything close to 400 continuous Watts. That's the part that most people forget. And if you're crossing that full-range speaker at 150Hz, you can probably dump 150% more power into it, if only because you're running less of a risk of launching the woofer into the stratosphere with low bass.
Sure, you always have to be careful... but just because a top says it can handle 400w RMS doesn't mean you can only put a 400w amp on it.
 
#10
Vinny D said:
This is the only spec. that ever matters: Full Range 400w continuous

Nothing is stopping you from using a much larger amplifier then needed....but the LS1503 is only a 400 watt speaker.
Click to expand...

Unless you are in the business of amplifying test signals you are leaving a good 6 dB of available SPL on the table by only using a 400 watt amp with a 400 watt speaker box.

At least twice the thermal limit of the speaker box and a properly configured speaker management system (and a good set of ears) is generally considered best practice among people who do this sort of thing a lot.
 
#11
thumbknuckle said:
Unless you are in the business of amplifying test signals you are leaving a good 6 dB of available SPL on the table by only using a 400 watt amp with a 400 watt speaker box.

At least twice the thermal limit of the speaker box and a properly configured speaker management system (and a good set of ears) is generally considered best practice among people who do this sort of thing a lot.
Click to expand...

I do this sort of thing alot....
And yes...if you are going to use proper limiters & filters you can use just about any size amp you want.
However...in this case the OP doesn't mention any speaker management, limiters etc... so he is best to power at or close to the RMS rating.
 
#13
thumbknuckle said:
The OP has a Driverack PA. Not the fanciest thing in the world but in my experience they work fine.
Click to expand...

This is true. I do crossover @ 100 hz with a LR 24 slope and structured the whole schmear (including limiters) with pink noise. I have a pretty good idea as to where I stand in terms of system capabilities and limitations. Given the various venue demands, I think I can (and have) pull this off with two 2450's as previously suggested.

Riis
 
#15
uhdinator said:
Carvin recommends 600-1200 range right on their specs on their website.
A bridged 1450 would work fine too
And Give 725 per speaker with 2-8 ohm cabs. Follow the drive rack gain staging on their web.
Click to expand...

You mean bridged and feeding the daisy-chained mains, correct? As mentioned, I could also pull this off with the 2450 as I have one to spare. The RMX's have handled 2 ohms / side with no problems in the past. Sidenote: as I understand it, bridged mono operation works best with a single 8 ohm load as it accommodates the the wider voltage swings.

The gain staging tutorial you mentioned is a must for those who have limited experience!

Riis
 
#18
All amp specs are listed/based on the 8 ohm load. Damping factor, THD, and noise specs are lower at 4 ohm or 2 ohm.
Its not significant enough to worry about for live sound.

Amps that can run min 2 ohm per channel will be 4 ohm min for bridge mode.

Amps that can only do 4 ohm min per channel will only do 8 ohm min bridge mode. If you go below the min ohm rating you will eventually let the smoke out of the box.

If those subs happen to be 4 ohm and you were paralleling them on a bridged 1450, it's getting a 2 ohm load, would be sending more than 1450w to the pair.
 
#19
Zooberwerx said:
This is true. I do crossover @ 100 hz with a LR 24 slope and structured the whole schmear (including limiters) with pink noise. I have a pretty good idea as to where I stand in terms of system capabilities and limitations. Given the various venue demands, I think I can (and have) pull this off with two 2450's as previously suggested.

Riis
Click to expand...

OK, this is all "pink noise" to me. Where is a good source for a TOTAL live sound noob to start learning. I'm starting a new band and we're gonna need a PA. All the bands I've been in already had a PA and some one to run it. I don't wanna hijack this thread so maybe PM me your recommendations for a starting point.
 
#20
I run a similar set up in mono with 1 2450, the subs on 1 channel and the tops on the other. In smaller bars I have done the same with a 1202 (half the power of the 2450)
My subs are summed to 2 ohms though... I was thinking of going stereo but would need 2x the power for the tops i currently have or need to add an amp..2 more spaces in a rack I don't have.
 

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