burningbusch Posted March 9, 2004 Share Posted March 9, 2004 Dave, you are way simplifying this issue. There are many factors that contribute to the "sound" of an amplifier, e.g. THD, slew rate, damping factor. How an amp specs with a test signal and how it tests/sounds with full range, dynamic music are two very different things. Amps are not sonically neutral. Busch. Link to comment Share on other sites More sharing options...
rylos Posted March 9, 2004 Share Posted March 9, 2004 Just for the hell of it, I went to QSC's web site because I own a QSC amp, a Powerlight. All of their Powerlight amps have a frequency response of at least 20 - 20k plus or minus 0.15 dB. That's flat, there ain't no color there. Unless you look at things like phases shifts, damping factor, etc. Damping factor won't show on the frequency plot, but has a huge effect on how "tight" the bass can sound. That's one of the reasons my Crown sounds solid, when a larger (but cheaper) amp I used to use had a much poorer sound, even on the same speakers. One listen to the way drums sounded when using the crown was all it took. With some amps the drums sound like drums, other amps the drums sound like someone whacking a cardboard box. "shit" happens. Success Takes Focus. Link to comment Share on other sites More sharing options...
Dave Horne Posted March 9, 2004 Share Posted March 9, 2004 Originally posted by rylos: Just for the hell of it, I went to QSC's web site because I own a QSC amp, a Powerlight. All of their Powerlight amps have a frequency response of at least 20 - 20k plus or minus 0.15 dB. That's flat, there ain't no color there. Unless you look at things like phases shifts, damping factor, etc. Damping factor won't show on the frequency plot, but has a huge effect on how "tight" the bass can sound. That's one of the reasons my Crown sounds solid, when a larger (but cheaper) amp I used to use had a much poorer sound, even on the same speakers. One listen to the way drums sounded when using the crown was all it took. With some amps the drums sound like drums, other amps the drums sound like someone whacking a cardboard box.A damping factor or 10 or more is adequate. The _lowest_ number I've seen on these kind of amps (if we can believe the hype in the advertising dept.) was 200, I believe, on the Yamaha amps. The QSC specs had 400 or 500. On any amp today, the damping factor is more than adequate and if you want to compare damping factors between amps, go ahead - you won't hear any difference (but a large number on a spec sheet does look good, doesn't it). A lot (most) of all this stuff is advertising hype. A quick google search brought this ... damping link quote: The point I'm trying to make is that the actual amplifier damping factor specification has little to do with the damping factor seen by a typical woofer...unless the woofer is welded directly to the output terminals of the amplifier ... there could be a patent here. :-) Many audio engineers are of the opinion that an amplifier damping factor of 10 or greater is adequate. Those sky high damping factors seen on the spec sheets of some amps are frequently just inventions of the marketing department and are irrelevant to actual system performance. The effect of higher source impedances (lower damping factors) is the same as adding series resistance in the speaker cable. Ultimately, the effect is a micro equalization of the frequency response as the voltage drive to the speaker becomes non-flat due to the frequency dependant impedance of the speaker. (adding series resistance creates a small peak at the speaker's own impedance peak...often on the order of 0.25 dB or so) The effect of the series resistance of the "damping" of the speaker is difficult to see when the problem is viewed this way. No guitarists were harmed during the making of this message. In general, harmonic complexity is inversely proportional to the ratio between chording and non-chording instruments. Link to comment Share on other sites More sharing options...
Dave Horne Posted March 9, 2004 Share Posted March 9, 2004 Originally posted by burningbusch: Dave, you are way simplifying this issue. There are many factors that contribute to the "sound" of an amplifier, e.g. THD, slew rate, damping factor. How an amp specs with a test signal and how it tests/sounds with full range, dynamic music are two very different things. Amps are not sonically neutral. Busch.Compare the THD of any amp made by any well known company - I'm talking about those rack amps that cost in excess of $500. The specs on all of them are simply fantastic. (The specs for my home stereo receiver's amp are incredible, but we'll leave that amp out of this discussion.) I think we will have have to agree to disagree (and I'll let someone else carry the ball on this). When I bought my amp for my rack case (for jobs) the only two factors I considered were RMS output per channel and the weight. That was it. I didn't care if the THD was 0.05 or 0.1 at its rated output. I didn't compare frequency response, slew rate, damping factor, IM distortion, color, number of lights, number of buttons, I just compared the output and the weight. If you want to buy your next amp on the advertised THD specs claimed by the manufacturer, go ahead. I won't hear the difference between 0.05 and 0.1 THD and I doubt you will either. A well designed amp is sonically neutral and if you want to really improve the sound of any system, replacing the speakers would be my first choice. Someone else can carry the ball on this. No guitarists were harmed during the making of this message. In general, harmonic complexity is inversely proportional to the ratio between chording and non-chording instruments. Link to comment Share on other sites More sharing options...
coyote Posted March 9, 2004 Share Posted March 9, 2004 How exactly does one determine whether an amp's frequency response sounds flat? Especially when one considers the distortion we accept as 'normal' nowadays - even some symphony orchestras in major concert halls have taken to enhancing their performances with amplification. Given the subjective nature of our individual sound experiences, this argument is kinda silly. I'm sure we could all agree if a given system had a particular frequency emphasis, but once you get past that it becomes a case of splitting hairs. And like I said above, you're free to spend many thousands of dollars to split those hairs if you want but it sure seems like overkill to me. I used to think I was Libertarian. Until I saw their platform; now I know I'm no more Libertarian than I am RepubliCrat or neoCON or Liberal or Socialist. This ain't no track meet; this is football. Link to comment Share on other sites More sharing options...
AmplifierExperts Posted March 9, 2004 Share Posted March 9, 2004 Originally posted by burningbusch: Dave, you are way simplifying this issue. There are many factors that contribute to the "sound" of an amplifier, e.g. THD, slew rate, damping factor. How an amp specs with a test signal and how it tests/sounds with full range, dynamic music are two very different things. Amps are not sonically neutral. Busch.Don't forget TIMD--Transient Intermodulation Distortion. That's the one that Matti Otala discovered in 1979 or so that causes loss of 'stage depth' because it smears time arrivals. A fellow named Holman devised a since-squarewave test signal to test for this distortion. TIMD is caused by high open loop gain. It's a transient clipping that gets corrected later on in the feedback loop, however, the timing information gets merged by this late correction, so the damage is done to the audio. Such amps had ultra-low IMD and THD, but musically, they lacked dimension and sounded flat. Best Regards, Mark A. Weiss, P.E. www.ampexperts.com - Link to comment Share on other sites More sharing options...
Griffinator Posted March 9, 2004 Share Posted March 9, 2004 Originally posted by burningbusch: Dave, you are way simplifying this issue. There are many factors that contribute to the "sound" of an amplifier, e.g. THD, slew rate, damping factor. How an amp specs with a test signal and how it tests/sounds with full range, dynamic music are two very different things. Amps are not sonically neutral. Busch.Thank you. This silliness about the 20-20K response being the only thing that matters in any piece of reproduction equipment is just inane. Dave, get over it. There are more factors to any piece of equipment than its 20-20K response. Fact is, Sony touts a low-end HT (HT stands for Home Theater, BTW) amplifier (STR-DE585) that's listed as 20-20Khz, +/-3dB. What isn't listed is slew, THD, THD+N, and a host of other mitigating factors. They list it as a 100WPC amp. What they don't tell you is that 100WPC is two channels driven, not all 6, and that it's at 1Khz with 0.9%THD. The head to head comparison on that amp versus a Yamaha HTR-5650 (discrete transistor amp - 80WPC all channels driven with less than 0.5%THD) at the same price point? The Yamaha drives the same pair of speakers louder, cleaner, and with less effort at the same volume level. Get over this 20-20K crap, Dave. There's a lot more to it than that. I suggest you do some research into the equipment you're pooh-poohing and understand the technology and why things like high-quality crystals, well-isolated power supplies, high-grade DAC circuits, quality discrete components (the basic stuff like caps, transistors, etc) have a dramatic effect on the final output quality. Or for that matter, ask GM why he doesn't use cheap surface-mounted high-tolerance parts in his EQ's, comps, etc. I'm sure he'd be happy to explain it to you. A bunch of loud, obnoxious music I USED to make with friends. Link to comment Share on other sites More sharing options...
Griffinator Posted March 9, 2004 Share Posted March 9, 2004 Originally posted by Dave Horne: Compare the THD of any amp made by any well known company - I'm talking about those rack amps that cost in excess of $500. The specs on all of them are simply fantastic. (The specs for my home stereo receiver's amp are incredible, but we'll leave that amp out of this discussion.) I think we will have have to agree to disagree (and I'll let someone else carry the ball on this). When I bought my amp for my rack case (for jobs) the only two factors I considered were RMS output per channel and the weight. That was it. I didn't care if the THD was 0.05 or 0.1 at its rated output. I didn't compare frequency response, slew rate, damping factor, IM distortion, color, number of lights, number of buttons, I just compared the output and the weight. If you want to buy your next amp on the advertised THD specs claimed by the manufacturer, go ahead. I won't hear the difference between 0.05 and 0.1 THD and I doubt you will either. A well designed amp is sonically neutral and if you want to really improve the sound of any system, replacing the speakers would be my first choice. Someone else can carry the ball on this.Never mind. Looks like you've already decided to not understand the technology. A bunch of loud, obnoxious music I USED to make with friends. Link to comment Share on other sites More sharing options...
Botch. Posted March 10, 2004 Share Posted March 10, 2004 Originally posted by Griffinator: Do you really believe, for example, that a Behringer A/D/A box is going to sound the same as an Apogee? It might, for a couple weeks at least... Botch "Eccentric language often is symptomatic of peculiar thinking" - George Will www.puddlestone.net Link to comment Share on other sites More sharing options...
MurMan Posted March 10, 2004 Share Posted March 10, 2004 Originally posted by Dave Horne: ...unless the woofer is welded directly to the output terminals of the amplifier ... Demanding audiophiles have known about this for years and require that all welding is done using gold welding rods. Casio PX-5S, Korg Kronos 61, Omnisphere 2, Ableton Live, LaunchKey 25, 2M cables Link to comment Share on other sites More sharing options...
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