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Post by audiosyndrome on Dec 13, 2015 15:56:10 GMT -5
Something amiss with the specs above. Output impedance 8 ohms. ON WAY from a solid state output stage. Very poorly designed or perhaps transformer coupled output.  Russ |
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Post by Boomzilla on Dec 13, 2015 15:59:21 GMT -5
Something amiss with the specs above. Output impedance 8 ohms. ON WAY from a solid state output stage. Very poorly designed or perhaps transformer coupled output. Russ No transformer audio coupling - solid state chips only. Output impedance is obviously misstated. They mean that they recommend an 8-ohm speaker. Translation error. |
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Post by lionear on Dec 13, 2015 22:53:00 GMT -5
When you hook it up to a 4-ohm load. I know that in theory the wattage output doubles (ohm's law), but only if the power supply is sufficiently robust to deliver the extra current. Most amplifiers can NOT deliver that much current, so their four ohm output is less (sometimes significantly less) wattage than the theoretical 2x the 8-ohm output. Which brings up the next question. Since the power supply may already be "sagging" with 4-ohm loads, what does this do the the SOUND of the amp? Is there less bass control? Do the output transistors change their frequency response curve due to the higher operating temperatures? I realize that there are too many variables to give any absolutely factual answers, but assuming a standard A/B-class amplifier configuration, what should the listener be aware of to determine whether or not the amp is under stress. For purposes of this question, please assume operation WELL below the clipping range. Thanks - Boomzilla My guess is that you'll hear better bass from an amp that's better designed to handle low impedance. Many years ago, I was looking for an amp, and a dealer switched between three amps - each had the same source and the same speakers. The amps were part of a family of amps from the same manufacturer so I think they shared similar designs, etc. The difference was in the power: 20W, 40W and 60W. They were set to the same volume setting, and I was surprised to find that one didn't sound louder than the other. The biggest difference was in the bass - the 60W amp had a fuller sound in the lower midband, handled the bass more comfortably, etc. Of course, a lot will depend on the specifics. At what frequency does the speaker dip below 8 Ohms? The amp may have difficulty transferring energy to the speaker at that frequency. However, one might have an enclosure or driver resonance at about the same frequency, and so the dip in impedance may balance out and the overall result may be better sound. On the other hand, the Apogee Scintilla speakers would dip to 2 ohms in the high frequencies - and one would hear that as a roll-off in the high frequencies. As Tannoy found out many years ago, there seemed to be an ideal match between a specific speaker and a specific amp. The designer of NOLA speakers always shows off his speakers with Audio Research Ref amps. So it will depend on the specific amp and specific speaker..... and the rest of your system, room, etc. |
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Post by jackfish on Jan 1, 2016 21:49:54 GMT -5
If one is afraid they will not have enough power into 4 Ohms, get more power?
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Post by knucklehead on Jan 2, 2016 0:37:59 GMT -5
If one is afraid they will not have enough power into 4 Ohms, get more power? Or get 8ohm speakers. |
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Post by vcautokid on Jan 2, 2016 7:02:04 GMT -5
The real simple takeaway is get the amplifier that matches the speakers impedance characteristics. Some very narrow impedance swing speakers are fine with integrated and AVR applications. It is only with how much more you want beyond that listening window where you may want more power to keep things clean. Planars and Electrostatic speakers like the big Logans can see an incredibly low impedance. Your amplifier choice should take that into account.
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