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K2 Amplifier Heat


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#1 LCHoffman

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Posted 09 January 2006 - 12:53 AM

I purchased a Crown K2 amp off of ebay last week while home on vacation. The amp was delivered to me a couple of days ago, and the package was pretty badly busted up upon arrival. The front right corner of the box was so blown out that you could clearly read the "Crown" logo on the faceplate sticker, and there was a small gouge on the bottom corner of the faceplate on that side. The guy who sent me the amp had no idea how to prorerly package such a heavy item. Other than the small gouge, the amp appeared to be fine. While handling it though, I noticed that I could feel the internal components shift when I rotated the amp from a horizontal position to a vertical position. This was disconcerning, as you can imagine. Cautiously, I went ahead and plugged the unit into a wall outlet, and the power indicator lights came on. I then decided that it was safe to hook up to a system. I went ahead and replaced my Adcom 555 woofer amp with the Crown, and proceeded to run it in my system driving a pair of 8", 8 ohm woofers wired in parallel in an all active 3 way (not the intended service and big time overkill, but I didn't want to risk damaging anything expensive). The unit sounds fine, and it drives the woofers with no problem, as you would expect. The issue is that the unit is really, really, hot. I mean, it is almost too hot to hold your hand on it for a long period of time, and I'm only listening to the football commentators on TV. Does this seem like something is wrong with the amp? Having never owned a pro amp before, I have no idea how hot they run. This amp is nearly idling with the load it's currently seeing.

For what it is worth, the amp is in bridged mode, and the channel 1 gain is at 0 (full gain). It is being fed a summed bass signal from a dbx Drive Rack PA, which runs pretty darned hot itself.  Lastly, the thermal overload lights on the front panel did not come on at any time during the 4 hours that the amp ran.

Any feedback on your experience with this amp would be appreciated.

Lou

#2 DGlass

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Posted 09 January 2006 - 09:45 AM

The K-2 will feel hot to the touch as the front panel and chassis are the amplifier's heat sinks. The K-2 however only generates about half the heat that a conventional amplifier of the same output power would produce. This is why the K-series amplifiers do not require a fan for cooling but they will still produce some heat.

#3 LCHoffman

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Posted 09 January 2006 - 10:13 PM

DGlass,

I understand what you are saying about the case being the heat dissipation mechanism.  However, it doesn't explain the excessive heat coming off of the thing driving a pair of home audio 8" midbass woofers.  An Adcom 555 amplifier with 1/3 the power delivery potential of the Crown never even got warm under the same conditions.  I should bring home a temperature gun from work and measure the surface temperature of the amp so that I have some real numbers to share with you.  "Hot to the touch" is just too subjective.  Are there any tests that I can run to determine if the amp is drawing excessive current?  I can probably find an amp meter to measure idle current on the plug.

Lou

#4 DGlass

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Posted 10 January 2006 - 08:43 AM

Without getting into the whole technical description of the K series amplifiers...

They K-series amps are a PWM switching output stage amplifier. The switching done in the amplifier for the reproduction of the signal is accruing all the time the amplifier is reproducing a signal and is not in sleep mode. In other words when its on its on.  Thus it will be generating some heat even when it is only producing a low level signal. However, compared to a conventional linear output stage amplifier it produces about half the heat for the same output. You can’t get that type of power without some heat. Take a look at the BTU/Hr rating of the K-2 as compared to the MA-2402 (that has the same output power) and you will see that the K-2 is a lot more efficient. The MA-2402 is a linear amplifier design and if its fan was disabled the amp would shortly, even at idle, go into thermal protection.

http://www.crownaudio.com/pdf/amps/k1k2calc.pdf
http://www.crownaudio.com/pdf/amps/131509.pdf

Because of the efficiency of the K-2 amplifiers they do not require a fan for internal cooling and rely on their chassis and front panel for “Convection” cooling and the TLC circuit for protection. If the TLC/Thermal light comes on than the amplifier will start limiting its output until the thermal issue goes away in that channel or channels.

In the old days of DC300 amplifiers we used convection cooling. During those days I have seen DC300s (rated for only175w/8-ohms) so hot you could fry an egg on them and that was with a window box fan blowing on them. The K-2 is rated for 500 watts/8-ohms and yes it will get hot to the touch its Convection cooled. smile.gif

If you desire to test the current draw of the amplifier the above mentioned sheets will give you an average of were you would be at for inputs of different Duty Cycles.

#5 MoreCowbell

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Posted 17 January 2006 - 11:55 AM

I use two K2's in my band, one for mids/highs one for subs.  I've found at moderately loud full band volumes the amps get fairly hot to the touch on the top towards the front.  Not so hot it would burn your hand, but hot enough that it would make you think twice, more than just warm.  That's after a 4 hour show, no fan or anything on it, maybe 2 rack spaces between the amps.

Based on this unscientific info, something sounds odd about your scenario, I wouldn't think they would be THAT hot.  There also shouldn't be anything rattling around inside.

Hope that helps.

#6 LCHoffman

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Posted 21 January 2006 - 10:21 AM

Thanks for sharing your experience.  Yep, that's what I was thinking also.  I reported the damage to UPS over a week ago, and I haven't heard anything from them since.  We'll see what transpires.

Lou

#7 Ghost_Dog

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Posted 22 January 2006 - 05:43 PM

QUOTE(LCHoffman @ Jan 21 2006, 11:21 AM)
Thanks for sharing your experience.  Yep, that's what I was thinking also.  I reported the damage to UPS over a week ago, and I haven't heard anything from them since.  We'll see what transpires.

Lou



If you think it is ideed defective then you better just get a refund from the seller and let him handle UPS...UPS dont pay out if it was not packaged correctly...*beep* they dont pay out even if it was.  laugh.gif