sfogg Posted January 1, 2006 Share Posted January 1, 2006 "Don't know what is meant by true RMS meter" Root mean square. If you don't have an RMS meter you are measuring point to point so the RMS wattage will be lower. "The amp is definitely feeding a load, " The amp is not feeding a load like a speaker. "I saw the meter rise as I turned up volume."" Of course it did. Volume is directly related to voltage/wattage. Turn down the volume and the meter is going to go down too. During the quiet parts of the songs the meter is going to drop too. "If I understand Craig's "transients" issue, that would mean the meter would lag behind the peaks, correct? " To a degree that method will give you average levels well. There is a better way to determine what you max possible wattage would be for transients. With your speakers connected play some of your music and set the volume to your typical listening level and measure the average level. Now change the CD to a CD that has a test tone on it such as the stereophile test CDs. Play the tone and measure its voltage. From that you can covert to wattage. Then you can calculate the max needed wattage by looking at the recorded level of the test tone. For example if it was recorded at -20dB you would multiple the wattage you calculated above by 100 to determine what the max possible power would need to be to handle everything possible on a CD at that volume setting. Shawn Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted January 1, 2006 Share Posted January 1, 2006 Actually, I calculated 25 v = 78 watts in that channel yes, yes, yes ...no peak, no real impedance, freq, etc let's NOT go down the Forum Path of showing just how intelligent we all are by Anal-izing every freakin' detail ... at least we Now Have An Idea ... of what Jeff is doin' ...OK ..??? Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 1, 2006 Share Posted January 1, 2006 I'm not all together convinced that using two seperate CD's one with test tones and one with music is going to really give accurate answer. Music CD's are recorded at such wildly different levels. Craig Quote Link to comment Share on other sites More sharing options...
jpm Posted January 1, 2006 Share Posted January 1, 2006 "The preamp has a more mission critical task than the power amp, IMO." I agree. No matter what amp I use, the music sounds 'peachy'. Hi Dean! This is an interesting comment. As you know I run a ss amp. My preamp is a British Rega Cursa... I'm told it's tube like in sound. Do you think it is? Does anyone have any feedback on the Rega Pre amp? Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted January 1, 2006 Share Posted January 1, 2006 Craig ... what is the derivation of the formula you used in this application .... curious ...[:^)] Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted January 1, 2006 Share Posted January 1, 2006 Jeff, Is your meter a true RMS meter or is it just giving peak to peak voltages? Are you feeding it music or a test signal? Many cheap meters aren't very accurate on AC at anything but 60hz. The formula to calculate watts requires the load source... if you unplugged your speakers the amp isn't feeding a load. Since it is a SS low output impedance amp the voltage shouldn't change much when you plug a load back in but it is something to keep in mind anyway. Lastly.... the level you are measuring... is this how loud you are actually listening at or are you just cranking things up to make measurements? Shawn Don't know what is meant by true RMS meter. Feeding it music, but with speakers disconnected. The amp is definitely feeding a load, I saw the meter rise as I turned up volume. The level I measured is what I listen to when I want to just crank for 3 or 4 songs. I do it regularly, but my "regular" level is when I play drums, which is well below that. If I understand Craig's "transients" issue, that would mean the meter would lag behind the peaks, correct? Meaning the margin of error would be skewed toward the low side? Lastly, FYI, the meter stayed fairly steady between 20 and 25 volts - it wasn't all over the place. Just FYI. I'm gonna take a quick shower and come back to see what answers I get. I'd especially like to see the conversion to SPL's through the KHorns. jeff ... ya gotta have a Load .... hookem up them KH Quote Link to comment Share on other sites More sharing options...
sfogg Posted January 1, 2006 Share Posted January 1, 2006 Craig, Yes they are, however peak level is peak level on all CDs. 0dBFS. The difference is some CDs average is much closer to 0dBFS then other CDs. That is why you use his music to get the average level on what he listens to. Then for peak you use a known reference level noise with the pre-amp at the same volume level as the music. That will give you the max possible level that any CD can produce at that volume setting on the pre-amp. Far more accurate then trying to guess peak levels (PWKs add 13dB) or then trying to measure them with slow equipment. Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted January 1, 2006 Share Posted January 1, 2006 Duke, "ya gotta have a Load ...." For the Crown it likely will make little difference actually. Measuring output unloaded and loaded on the same test signal is actually how you measure/calculate output impedance of an amp. On an amp that has very low output impedance the voltage will barely change loaded to unloaded. For an amp with high output impedance there will be a much larger difference in voltage loaded to unloaded. Shawn Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 1, 2006 Share Posted January 1, 2006 Actually, I calculated 25 v = 78 watts in that channel yes, yes, yes ...no peak, no real impedance, freq, etc let's NOT go down the Forum Path of showing just how intelligent we all are by Anal-izing every freakin' detail ... at least we Now Have An Idea ... of what Jeff is doin' ...OK ..??? Duke, This method is flawed. As Shawn stated meters can be so wildly off especially the cheap ones, then factor in the changing impedance this test is a joke. If his meter is not a true RMS meter and is reading peak - peak voltage then he is not even remotely near 78 watts. New formula 25 p-p VAC X .707 = 17.675 RMS Volts AC 17.675 X 17.675 = 312.405/ 8 0hms = 39.05 watts Then factor in the the meter itself could be off by a large margin and then at any given frequency the speaker load could be 4 ohms or 30 ohms?? this test is a joke. Craig Quote Link to comment Share on other sites More sharing options...
Jeff Matthews Posted January 1, 2006 Author Share Posted January 1, 2006 Okay, just for grins, let's go with Duke's 78 watts. I just gotta know - why is it that my 90 watt/channel Marantz 1180DC of years long ago did not nearly deliver the precision and punch on peaks that my Crown does? It seems running 78 watts, there might be enough headroom in both, so what gives? The Crown definitely out-classes the Marantz 1180DC hands down. Here's 1180DC specs: (go down the page for all the specs) http://www.classic-audio.com/marantz/1180dc.html Here's the Crown specs: http://64.233.187.104/search?q=cache:T425d8agDMMJ:www.crownaudio.com/pdf/amps/133775.pdf+crown+%22microtech+1200%22+specifications&hl=en So, tell me, gurus, what is it about the Crown, if not power, that makes it outclass a very powerful Marantz? Quote Link to comment Share on other sites More sharing options...
Jeff Matthews Posted January 1, 2006 Author Share Posted January 1, 2006 And "double" goes to my question assuming Craig's speculation that I might be running wattage in the 30's. Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted January 1, 2006 Share Posted January 1, 2006 OK, Craig ... I'l buy into your formula of Peak-Peak volts as most likely he does not have an averaging meter .. but ... the test ain't a joke ... we now know he's not listening to 1 Watt .....[] Quote Link to comment Share on other sites More sharing options...
sfogg Posted January 1, 2006 Share Posted January 1, 2006 Could be different frequency response, different damping, different current delivery (check how each amps power rating changes to different loads), distortion differences, actual power outputs (not specs)...etc...etc.... There is a lot more to an amp then just a one specification. Shawn Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted January 1, 2006 Share Posted January 1, 2006 Jeff ... Craigs formula .. does get us in the ballpark, bud correcting for your meter not being True RMS Quote Link to comment Share on other sites More sharing options...
Jeff Matthews Posted January 1, 2006 Author Share Posted January 1, 2006 And I'll throw the specs of the Marantz 2230 30 watt/channel that we still have downstairs. This amp is a sorry joke compared to the Crown. Yeah, it gets somewhat loud, but dead with no peaks, punch and speed. But yet 30 watts..... Why is it not even in the orbit of the Crown if I'm listening to 39 watts? So what gives? http://www.classic-audio.com/marantz/2230.html Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 1, 2006 Share Posted January 1, 2006 OK, Craig ... I'l buy into your formula of Peak-Peak volts as most likely he does not have an averaging meter .. but ... the test ain't a joke ... we now know he's not listening to 1 Watt .....[] I never said he was listening at 1 watt Quote Link to comment Share on other sites More sharing options...
Jeff Matthews Posted January 1, 2006 Author Share Posted January 1, 2006 Seems like nobody necessarily wants to venture down the specs trail on the comparative amps to see what makes them tick. If anybody cares, I'm all ears. I just don't know how to interpret all that stuff. Duke, if I'm running 39 watts, is that inclusive of peaks? It is hard to imagine that 1/2 way is 39 watts on a 310 watt/channel amp. That means there's 271 watts left in the second 1/2. Are you all sure of these calcs? Maybe you're giving me average watts and leaving out peaks..... Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 1, 2006 Share Posted January 1, 2006 And I'll throw the specs of the Marantz 2230 30 watt/channel that we still have downstairs. This amp is a sorry joke compared to the Crown. Yeah, it gets somewhat loud, but dead with no peaks, punch and speed. But yet 30 watts..... Why is it not even in the orbit of the Crown if I'm listening to 39 watts? So what gives? http://www.classic-audio.com/marantz/2230.html Jeff, Specs are not the be all end all. Face it those old Marantz amps are not even remotely similar to your beastly Crown. They have a sonic signature all there own. Very warm and soft much like a bone stock vintage tube amp. Craig Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 1, 2006 Share Posted January 1, 2006 What meter are you using? Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 1, 2006 Share Posted January 1, 2006 What music are you using? Quote Link to comment Share on other sites More sharing options...
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