Jump to content


Output rating question XLS vs DC 300A


  • Please log in to reply
4 replies to this topic

#1 Duke

Duke
  • Members
  • 3 posts

Posted 04 September 2011 - 08:38 AM

Hello,
I have a few DC 300A amps and a year ago purchased a XLS 802 so I could run 4 ohm full range cabs with enough power in stereo mode without overworking the DC 300s in mono mode running a 4 ohm load. ( I do realize that the DC 300 is not spec'd to run @ 4 ohms mono, it does get hot)
If the XLS 802 is rated at 800w @ 4ohms, I do not understand why it is much quieter than a DC 300A run in mono with a 4 ohm load. Even at 4 ohms, the DC300 should not put out 800w, and it is still much louder than the 802? I am running these to Community full range cabs rated at 200 rms / 500 program.
Am I missing something, or do we measure output ratings differently from amp to amp?

Duke

#2 Kevin Heber

Kevin Heber

    Power User

  • Crown Staff
  • 883 posts

Posted 06 September 2011 - 01:14 PM

I'm guessing what you are noticing is the input sensitivity difference.  For the same input signal, the DC300 will have about twice as much output.  However, the XLS will be able to push that signal further & harder.  So the difference you are paying for in watts is noticeable at the very top end of its capability, just below and at clipping.  In that range, the XLS will push the same signal into the same speakers to a higher SPL at all frequencies, assuming the speaker can handle the power.

#3 Duke

Duke
  • Members
  • 3 posts

Posted 06 September 2011 - 05:38 PM

QUOTE(Duke @ Sep 4 2011, 09:38 AM) View Post
Hello,
I have a few DC 300A amps and a year ago purchased a XLS 802 so I could run 4 ohm full range cabs with enough power in stereo mode without overworking the DC 300s in mono mode running a 4 ohm load. ( I do realize that the DC 300 is not spec'd to run @ 4 ohms mono, it does get hot)
If the XLS 802 is rated at 800w @ 4ohms, I do not understand why it is much quieter than a DC 300A run in mono with a 4 ohm load. Even at 4 ohms, the DC300 should not put out 800w, and it is still much louder than the 802? I am running these to Community full range cabs rated at 200 rms / 500 program.
Am I missing something, or do we measure output ratings differently from amp to amp?

Duke


Kevin,
Not sure I fully understand the sensitivity setting---"Note that lower sensitivity values will increase the level of output for any given input."   So the XLS 802D is rated for a sensitivity if 1.25v, but the DC 300 A has an input sensitivity setting of 1.75v. So if I keep my levels constant prior to the amplifier inputs, shouldn't the 802 be "louder" with the lower sensitivity value?
Can the input voltage be measured with a standard digital volt meter? Is this measuring the signal output of the crossover?

How long will the DC300 A hold up running the 4 ohm bridge load.....will this be stable as long as I can keep them cooled sufficiently?

#4 Kevin Heber

Kevin Heber

    Power User

  • Crown Staff
  • 883 posts

Posted 07 September 2011 - 09:08 AM

You are correct -- I was assuming the DC300A to be a 0.775V sensitivity.  Is it possible that it was modified?  See page 23 here -
http://www.crownaudio.com/pdf/legacy/dc300a2.pdf

You can indeed measure input voltage (on a sine wave signal coming from a preamp or crossover) with a multimeter.

Cooling the DC300A to run a 4-ohm bridge load is the main thing for the output transistors, but there is also the matter that the other components in the output stage were not designed for that amount of current, so those could fail prematurely.

#5 Duke

Duke
  • Members
  • 3 posts

Posted 07 September 2011 - 06:39 PM

QUOTE(Kevin Heber @ Sep 7 2011, 10:08 AM) View Post
You are correct -- I was assuming the DC300A to be a 0.775V sensitivity.  Is it possible that it was modified?  See page 23 here -
http://www.crownaudio.com/pdf/legacy/dc300a2.pdf

You can indeed measure input voltage (on a sine wave signal coming from a preamp or crossover) with a multimeter.

Cooling the DC300A to run a 4-ohm bridge load is the main thing for the output transistors, but there is also the matter that the other components in the output stage were not designed for that amount of current, so those could fail prematurely.



Thanks.. I appreciate the info. I have two of the DC300A running at 4 ohms bridged each driving one full range cab rated at 500w program. These amps came from different places, so I doubt they are modified in any way to create higher output. The only mod I know of is in one that is an earlier model, without the bridge / mono switch. I went in and did the internal bridge connections myself, other than that I did not see anything to indicate additional mods.

So, do we measure output wattage differently these days?----I assume the DC300 driven at that 4 ohm bridged load will produce an output of approx. 550-600w. Am I under calculating the output?