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#1
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So what's the skinny on digital amps?
I don't have any first-hand experience with "class D" digital
amplifiers, but I saw an ad for a PowerAcoustik model that supposedly puts out 2300W RMS into one ohm, and costs just a little over $300. Even if they're wildly inflating the power numbers, that still sounds like a hell of a deal. I paid almost that much for a Linear Power 2202IQ (about 375W RMS mono) in 1991, and $300 is about what I paid for the used PPI A1200.2 (1200 WRMS mono) that I'm using now. I know that digital amps are bandwidth-limited, making them more suitable as subwoofer amps than as full-range amps, but are there any other drawbacks to this design? Scott Gardner |
#2
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So what's the skinny on digital amps?
First, I know your calling them "digital" because thats the way they are
marketed. So I am not attacking your choice of words. But there is no such thing as a "digital amplifier". Digital means 1s and 0s. You can't amplify 1s and 0s! You can convert an analog singal to digital, process the signal, and convert it back to analog for amplifying. Hence "digital singal processing". I have no idea why they are called "digital", but it just bugs me.... To try and answer your question though, they are much more efficient than a typical class A/B design. They take less space. Those are the major advantages. I wont say "all" of them, because I dont know for sure, but every one I have seen has a fairly poor damping factor, which means less "control" of the sub, so it could sound sloppy (compared to a good Class A/B). Overall they are not as good for sound quality as a Class A/B of equal quality build. Class D (or Class T, or BD, or whatever) use a different type switching which makes them useless for full range. They can't operate fast enough for full range. Infinity used to make a Beta series amp (they even had the words DIGITAL on the amps) that was supposed to be OK for full range. Not sure how well they did it, but they were supposed to be capable of it. I heard them used on subs, never on full range, so I can't say. So with some exceptions, the basic rule is subwoofer use only. If I were you, I would NOT get rid of that PPI A1200 for a PowerAcoustik ANYTHING. Class D or not. But, that's just me. -- John Spagnolo - teamROCS #016 Multi Media Xpress Car Audio www.mmxpress.com "It's about the music stupid!" John "Batvette" Lucier 98' R.A.C. FAQ: http://www.mobileaudio.com/rac-faq/ JL Audio Tech Section: http://www.jlaudio.com/tutorials MMXpress Tech Section: http://www.mmxpress.com/technical/ "Scott Gardner" wrote in message ... I don't have any first-hand experience with "class D" digital amplifiers, but I saw an ad for a PowerAcoustik model that supposedly puts out 2300W RMS into one ohm, and costs just a little over $300. Even if they're wildly inflating the power numbers, that still sounds like a hell of a deal. I paid almost that much for a Linear Power 2202IQ (about 375W RMS mono) in 1991, and $300 is about what I paid for the used PPI A1200.2 (1200 WRMS mono) that I'm using now. I know that digital amps are bandwidth-limited, making them more suitable as subwoofer amps than as full-range amps, but are there any other drawbacks to this design? Scott Gardner |
#3
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So what's the skinny on digital amps?
Oh, I'm not getting rid of my PPI amps for anything. I just came
across the PowerAcoustik model when I was researching some other stuff for a friend. I don't know anything about that brand, I was just using it as an example. As for why they're called "digital", I believe it's in reference to the power supply switching method. I know it's a marketing term, that's why I put "class D" in quotes. I wouldn't be too concerned about the low damping factor. The only reason that class AB amps have such astronomical damping factors is because damping factor is related to the amount of global negative feedback in the amplifier design, and AB amps use a LOT of global negative feedback. If you look at class A tube amplifiers for home use, some of them have damping factors of 20 or even lower, and they have no problems controlling subwoofer movement. Damping factor turned into a marketing selling point for car amplifiers, but it's really just a by-product of the feedback circuitry. I think you'd probably be hard-pressed to tell the difference between a damping factor of 50 or 500, all else being equal. Some of the best-sounding pure class A tube amps have damping factors of less than 10. However, these tend to be single-ended triode amps, and generally put out less than 10 watts per channel, so driving huge subs isn't a priority with these amps. So, it sounds like if sound quality isn't your top priority, and you're just using it to efficiently throw a LOT of power to a subwoofer, a "class D" amplifier might be a good choice. Do you know of any models that are accurately-rated as to their power output? I'm still getting over that 2300W PowerAcoustik amp for $300, and I'd like to find out if that kind of watts-per-dollar ratio is really possible with a "digital" amp. Scott Gardner On Sun, 21 Dec 2003 12:35:06 GMT, "John Spagnolo MMXpress.com" wrote: First, I know your calling them "digital" because thats the way they are marketed. So I am not attacking your choice of words. But there is no such thing as a "digital amplifier". Digital means 1s and 0s. You can't amplify 1s and 0s! You can convert an analog singal to digital, process the signal, and convert it back to analog for amplifying. Hence "digital singal processing". I have no idea why they are called "digital", but it just bugs me.... To try and answer your question though, they are much more efficient than a typical class A/B design. They take less space. Those are the major advantages. I wont say "all" of them, because I dont know for sure, but every one I have seen has a fairly poor damping factor, which means less "control" of the sub, so it could sound sloppy (compared to a good Class A/B). Overall they are not as good for sound quality as a Class A/B of equal quality build. Class D (or Class T, or BD, or whatever) use a different type switching which makes them useless for full range. They can't operate fast enough for full range. Infinity used to make a Beta series amp (they even had the words DIGITAL on the amps) that was supposed to be OK for full range. Not sure how well they did it, but they were supposed to be capable of it. I heard them used on subs, never on full range, so I can't say. So with some exceptions, the basic rule is subwoofer use only. If I were you, I would NOT get rid of that PPI A1200 for a PowerAcoustik ANYTHING. Class D or not. But, that's just me. -- John Spagnolo - teamROCS #016 Multi Media Xpress Car Audio www.mmxpress.com "It's about the music stupid!" John "Batvette" Lucier 98' R.A.C. FAQ: http://www.mobileaudio.com/rac-faq/ JL Audio Tech Section: http://www.jlaudio.com/tutorials MMXpress Tech Section: http://www.mmxpress.com/technical/ "Scott Gardner" wrote in message ... I don't have any first-hand experience with "class D" digital amplifiers, but I saw an ad for a PowerAcoustik model that supposedly puts out 2300W RMS into one ohm, and costs just a little over $300. Even if they're wildly inflating the power numbers, that still sounds like a hell of a deal. I paid almost that much for a Linear Power 2202IQ (about 375W RMS mono) in 1991, and $300 is about what I paid for the used PPI A1200.2 (1200 WRMS mono) that I'm using now. I know that digital amps are bandwidth-limited, making them more suitable as subwoofer amps than as full-range amps, but are there any other drawbacks to this design? Scott Gardner |
#4
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So what's the skinny on digital amps?
There's nothing wrong with the sound quality of a class D amp.
Also, a good discussion on damping factor can be found he http://www.diyspeakers.net/Articles/...G%20FACTOR.pdf "Scott Gardner" wrote in message ... Oh, I'm not getting rid of my PPI amps for anything. I just came across the PowerAcoustik model when I was researching some other stuff for a friend. I don't know anything about that brand, I was just using it as an example. As for why they're called "digital", I believe it's in reference to the power supply switching method. I know it's a marketing term, that's why I put "class D" in quotes. I wouldn't be too concerned about the low damping factor. The only reason that class AB amps have such astronomical damping factors is because damping factor is related to the amount of global negative feedback in the amplifier design, and AB amps use a LOT of global negative feedback. If you look at class A tube amplifiers for home use, some of them have damping factors of 20 or even lower, and they have no problems controlling subwoofer movement. Damping factor turned into a marketing selling point for car amplifiers, but it's really just a by-product of the feedback circuitry. I think you'd probably be hard-pressed to tell the difference between a damping factor of 50 or 500, all else being equal. Some of the best-sounding pure class A tube amps have damping factors of less than 10. However, these tend to be single-ended triode amps, and generally put out less than 10 watts per channel, so driving huge subs isn't a priority with these amps. So, it sounds like if sound quality isn't your top priority, and you're just using it to efficiently throw a LOT of power to a subwoofer, a "class D" amplifier might be a good choice. Do you know of any models that are accurately-rated as to their power output? I'm still getting over that 2300W PowerAcoustik amp for $300, and I'd like to find out if that kind of watts-per-dollar ratio is really possible with a "digital" amp. Scott Gardner On Sun, 21 Dec 2003 12:35:06 GMT, "John Spagnolo MMXpress.com" wrote: First, I know your calling them "digital" because thats the way they are marketed. So I am not attacking your choice of words. But there is no such thing as a "digital amplifier". Digital means 1s and 0s. You can't amplify 1s and 0s! You can convert an analog singal to digital, process the signal, and convert it back to analog for amplifying. Hence "digital singal processing". I have no idea why they are called "digital", but it just bugs me.... To try and answer your question though, they are much more efficient than a typical class A/B design. They take less space. Those are the major advantages. I wont say "all" of them, because I dont know for sure, but every one I have seen has a fairly poor damping factor, which means less "control" of the sub, so it could sound sloppy (compared to a good Class A/B). Overall they are not as good for sound quality as a Class A/B of equal quality build. Class D (or Class T, or BD, or whatever) use a different type switching which makes them useless for full range. They can't operate fast enough for full range. Infinity used to make a Beta series amp (they even had the words DIGITAL on the amps) that was supposed to be OK for full range. Not sure how well they did it, but they were supposed to be capable of it. I heard them used on subs, never on full range, so I can't say. So with some exceptions, the basic rule is subwoofer use only. If I were you, I would NOT get rid of that PPI A1200 for a PowerAcoustik ANYTHING. Class D or not. But, that's just me. -- John Spagnolo - teamROCS #016 Multi Media Xpress Car Audio www.mmxpress.com "It's about the music stupid!" John "Batvette" Lucier 98' R.A.C. FAQ: http://www.mobileaudio.com/rac-faq/ JL Audio Tech Section: http://www.jlaudio.com/tutorials MMXpress Tech Section: http://www.mmxpress.com/technical/ "Scott Gardner" wrote in message ... I don't have any first-hand experience with "class D" digital amplifiers, but I saw an ad for a PowerAcoustik model that supposedly puts out 2300W RMS into one ohm, and costs just a little over $300. Even if they're wildly inflating the power numbers, that still sounds like a hell of a deal. I paid almost that much for a Linear Power 2202IQ (about 375W RMS mono) in 1991, and $300 is about what I paid for the used PPI A1200.2 (1200 WRMS mono) that I'm using now. I know that digital amps are bandwidth-limited, making them more suitable as subwoofer amps than as full-range amps, but are there any other drawbacks to this design? Scott Gardner |
#5
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So what's the skinny on digital amps?
So, it sounds like if sound quality isn't your top priority, and
you're just using it to efficiently throw a LOT of power to a subwoofer, a "class D" amplifier might be a good choice. Do you know of any models that are accurately-rated as to their power output? I'm still getting over that 2300W PowerAcoustik amp for $300, and I'd like to find out if that kind of watts-per-dollar ratio is really possible with a "digital" amp. I was looking at getting a pair of Kenwood KAC-810D's a while ago. They go for abouy $750 CDN each, and IIRC they are rated for 800W into 2 ohms, or 1600W into 1 ohm. I'd be a little warry of a $300 USD amp that claims 2300 watts but I dunno... Aaron |
#6
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So what's the skinny on digital amps?
On Sun, 21 Dec 2003 10:37:44 -0500, "Mark Zarella"
wrote: There's nothing wrong with the sound quality of a class D amp. Also, a good discussion on damping factor can be found he http://www.diyspeakers.net/Articles/...G%20FACTOR.pdf I've already read that article, and it says basically what I posted, that high damping factors are a by-product of feedback, and that higher numbers really don't buy you anything. Actually, Pierce goes as far to say that differences in damping factor are inaudible over 20. I at least went as high as 50. Scott Gardner "Scott Gardner" wrote in message ... Oh, I'm not getting rid of my PPI amps for anything. I just came across the PowerAcoustik model when I was researching some other stuff for a friend. I don't know anything about that brand, I was just using it as an example. As for why they're called "digital", I believe it's in reference to the power supply switching method. I know it's a marketing term, that's why I put "class D" in quotes. I wouldn't be too concerned about the low damping factor. The only reason that class AB amps have such astronomical damping factors is because damping factor is related to the amount of global negative feedback in the amplifier design, and AB amps use a LOT of global negative feedback. If you look at class A tube amplifiers for home use, some of them have damping factors of 20 or even lower, and they have no problems controlling subwoofer movement. Damping factor turned into a marketing selling point for car amplifiers, but it's really just a by-product of the feedback circuitry. I think you'd probably be hard-pressed to tell the difference between a damping factor of 50 or 500, all else being equal. Some of the best-sounding pure class A tube amps have damping factors of less than 10. However, these tend to be single-ended triode amps, and generally put out less than 10 watts per channel, so driving huge subs isn't a priority with these amps. So, it sounds like if sound quality isn't your top priority, and you're just using it to efficiently throw a LOT of power to a subwoofer, a "class D" amplifier might be a good choice. Do you know of any models that are accurately-rated as to their power output? I'm still getting over that 2300W PowerAcoustik amp for $300, and I'd like to find out if that kind of watts-per-dollar ratio is really possible with a "digital" amp. Scott Gardner On Sun, 21 Dec 2003 12:35:06 GMT, "John Spagnolo MMXpress.com" wrote: First, I know your calling them "digital" because thats the way they are marketed. So I am not attacking your choice of words. But there is no such thing as a "digital amplifier". Digital means 1s and 0s. You can't amplify 1s and 0s! You can convert an analog singal to digital, process the signal, and convert it back to analog for amplifying. Hence "digital singal processing". I have no idea why they are called "digital", but it just bugs me.... To try and answer your question though, they are much more efficient than a typical class A/B design. They take less space. Those are the major advantages. I wont say "all" of them, because I dont know for sure, but every one I have seen has a fairly poor damping factor, which means less "control" of the sub, so it could sound sloppy (compared to a good Class A/B). Overall they are not as good for sound quality as a Class A/B of equal quality build. Class D (or Class T, or BD, or whatever) use a different type switching which makes them useless for full range. They can't operate fast enough for full range. Infinity used to make a Beta series amp (they even had the words DIGITAL on the amps) that was supposed to be OK for full range. Not sure how well they did it, but they were supposed to be capable of it. I heard them used on subs, never on full range, so I can't say. So with some exceptions, the basic rule is subwoofer use only. If I were you, I would NOT get rid of that PPI A1200 for a PowerAcoustik ANYTHING. Class D or not. But, that's just me. -- John Spagnolo - teamROCS #016 Multi Media Xpress Car Audio www.mmxpress.com "It's about the music stupid!" John "Batvette" Lucier 98' R.A.C. FAQ: http://www.mobileaudio.com/rac-faq/ JL Audio Tech Section: http://www.jlaudio.com/tutorials MMXpress Tech Section: http://www.mmxpress.com/technical/ "Scott Gardner" wrote in message ... I don't have any first-hand experience with "class D" digital amplifiers, but I saw an ad for a PowerAcoustik model that supposedly puts out 2300W RMS into one ohm, and costs just a little over $300. Even if they're wildly inflating the power numbers, that still sounds like a hell of a deal. I paid almost that much for a Linear Power 2202IQ (about 375W RMS mono) in 1991, and $300 is about what I paid for the used PPI A1200.2 (1200 WRMS mono) that I'm using now. I know that digital amps are bandwidth-limited, making them more suitable as subwoofer amps than as full-range amps, but are there any other drawbacks to this design? Scott Gardner |
#7
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So what's the skinny on digital amps?
Class D amplifiers are quite effective at low frequencies, they have severe
problems with harmonic distortion at higher audio frequencies. It is for this reason they are popular as subwoofer amplifiers, but little else. Tripath (class T) amplifiers are fullrange amplifiers that sound just as good if not better then most class A/B amplifiers, and are just as efficient as class D amplifiers. To try and answer your question though, they are much more efficient than a typical class A/B design. They take less space. Those are the major advantages. I wont say "all" of them, because I dont know for sure, but every one I have seen has a fairly poor damping factor, which means less "control" of the sub, so it could sound sloppy (compared to a good Class A/B). Overall they are not as good for sound quality as a Class A/B of equal quality build. Class D (or Class T, or BD, or whatever) use a different type switching which makes them useless for full range. They can't operate fast enough for full range. Infinity used to make a Beta series amp (they even had the words DIGITAL on the amps) that was supposed to be OK for full range. Not sure how well they did it, but they were supposed to be capable of it. I heard them used on subs, never on full range, so I can't say. So with some exceptions, the basic rule is subwoofer use only. If I were you, I would NOT get rid of that PPI A1200 for a PowerAcoustik ANYTHING. Class D or not. But, that's just me. |
#8
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So what's the skinny on digital amps?
K, so you already knew the "skinny" on the circuitry, you were just amazed
at the price points! :-) Gotcha. And I know what you mean about the much-to-high damping factor on some amps not mattering. PPI is one that comes to mind for having one that is VERY high. Overkill, but it looks good. The amp you mentioned, low power pure tube amps, are like you said, low power. Damping doesn't really come into play much with that kind of wattage. Tube amps also tend to have very high (relatively) THD ratings. Compared to some amps, very high. Some of them with 6% and I've seen as high as 10%. But there are other factors that negate these points. The end, IMHO, is a much warmer sound. I think most of the class D's that are out now in car audio have fine sound quality, and I doubt *I* could tell the difference. I was just trying to give you the simple differences in design, and keep it simple. Obviously you already knew the differences! I still hate the words "digital amp". :-) -- John Spagnolo - teamROCS #016 Multi Media Xpress Car Audio www.mmxpress.com "It's about the music stupid!" John "Batvette" Lucier 98' R.A.C. FAQ: http://www.mobileaudio.com/rac-faq/ JL Audio Tech Section: http://www.jlaudio.com/tutorials MMXpress Tech Section: http://www.mmxpress.com/technical/ "Scott Gardner" wrote in message ... Oh, I'm not getting rid of my PPI amps for anything. I just came across the PowerAcoustik model when I was researching some other stuff for a friend. I don't know anything about that brand, I was just using it as an example. As for why they're called "digital", I believe it's in reference to the power supply switching method. I know it's a marketing term, that's why I put "class D" in quotes. I wouldn't be too concerned about the low damping factor. The only reason that class AB amps have such astronomical damping factors is because damping factor is related to the amount of global negative feedback in the amplifier design, and AB amps use a LOT of global negative feedback. If you look at class A tube amplifiers for home use, some of them have damping factors of 20 or even lower, and they have no problems controlling subwoofer movement. Damping factor turned into a marketing selling point for car amplifiers, but it's really just a by-product of the feedback circuitry. I think you'd probably be hard-pressed to tell the difference between a damping factor of 50 or 500, all else being equal. Some of the best-sounding pure class A tube amps have damping factors of less than 10. However, these tend to be single-ended triode amps, and generally put out less than 10 watts per channel, so driving huge subs isn't a priority with these amps. So, it sounds like if sound quality isn't your top priority, and you're just using it to efficiently throw a LOT of power to a subwoofer, a "class D" amplifier might be a good choice. Do you know of any models that are accurately-rated as to their power output? I'm still getting over that 2300W PowerAcoustik amp for $300, and I'd like to find out if that kind of watts-per-dollar ratio is really possible with a "digital" amp. Scott Gardner On Sun, 21 Dec 2003 12:35:06 GMT, "John Spagnolo MMXpress.com" wrote: First, I know your calling them "digital" because thats the way they are marketed. So I am not attacking your choice of words. But there is no such thing as a "digital amplifier". Digital means 1s and 0s. You can't amplify 1s and 0s! You can convert an analog singal to digital, process the signal, and convert it back to analog for amplifying. Hence "digital singal processing". I have no idea why they are called "digital", but it just bugs me.... To try and answer your question though, they are much more efficient than a typical class A/B design. They take less space. Those are the major advantages. I wont say "all" of them, because I dont know for sure, but every one I have seen has a fairly poor damping factor, which means less "control" of the sub, so it could sound sloppy (compared to a good Class A/B). Overall they are not as good for sound quality as a Class A/B of equal quality build. Class D (or Class T, or BD, or whatever) use a different type switching which makes them useless for full range. They can't operate fast enough for full range. Infinity used to make a Beta series amp (they even had the words DIGITAL on the amps) that was supposed to be OK for full range. Not sure how well they did it, but they were supposed to be capable of it. I heard them used on subs, never on full range, so I can't say. So with some exceptions, the basic rule is subwoofer use only. If I were you, I would NOT get rid of that PPI A1200 for a PowerAcoustik ANYTHING. Class D or not. But, that's just me. -- John Spagnolo - teamROCS #016 Multi Media Xpress Car Audio www.mmxpress.com "It's about the music stupid!" John "Batvette" Lucier 98' R.A.C. FAQ: http://www.mobileaudio.com/rac-faq/ JL Audio Tech Section: http://www.jlaudio.com/tutorials MMXpress Tech Section: http://www.mmxpress.com/technical/ "Scott Gardner" wrote in message ... I don't have any first-hand experience with "class D" digital amplifiers, but I saw an ad for a PowerAcoustik model that supposedly puts out 2300W RMS into one ohm, and costs just a little over $300. Even if they're wildly inflating the power numbers, that still sounds like a hell of a deal. I paid almost that much for a Linear Power 2202IQ (about 375W RMS mono) in 1991, and $300 is about what I paid for the used PPI A1200.2 (1200 WRMS mono) that I'm using now. I know that digital amps are bandwidth-limited, making them more suitable as subwoofer amps than as full-range amps, but are there any other drawbacks to this design? Scott Gardner |
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