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#81
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How Do I Determine A Power-Amp's Input Impedance?
Stewart,
If you don't understand *system* design, then you shouldn't be messing with passives. I guess I just don't see the value of passive audio gear. I appreciate that reducing the number of devices in the chain is always a good idea when all else is equal. But in this case all else is decidely not equal. An active output can drive cables with no HF loss, and the low output impedance reduces or avoids altogether RFI and other interference problems. An active input can be balanced to reduce hum and RFI. Further, the obssession some people have to avoid adding 0.001% distortion seems silly given that all loudspeakers have 100 times more distortion. And any room you're likely to put speakers in has a response that varies by 20-30 dB throughout the entire low end. Which makes it a basic lie - it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. Not to defend Manley. I have no use for tubes either. :-) --Ethan |
#83
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How Do I Determine A Power-Amp's Input Impedance?
On 14 Jan 2004 08:36:40 -0500, (Mike Rivers)
wrote: In article writes: I appreciate the advice, but as I said before I only have a digital multimeter at my disposal. It sounds like I'd have to bench the amp and connect it up to a tone or sine wave generator to do what you suggest. Am I interpreting you correctly? Well, yes. Your digital multimeter doesn't have an input impedance scale does it? It's not the same as resistance in most cases, in case that's what you were dreaming about. Actually, it pretty much is, in most cases. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#84
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How Do I Determine A Power-Amp's Input Impedance?
On 14 Jan 2004 08:36:40 -0500, (Mike Rivers)
wrote: In article writes: I appreciate the advice, but as I said before I only have a digital multimeter at my disposal. It sounds like I'd have to bench the amp and connect it up to a tone or sine wave generator to do what you suggest. Am I interpreting you correctly? Well, yes. Your digital multimeter doesn't have an input impedance scale does it? It's not the same as resistance in most cases, in case that's what you were dreaming about. Actually, it pretty much is, in most cases. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#85
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How Do I Determine A Power-Amp's Input Impedance?
On 14 Jan 2004 08:36:40 -0500, (Mike Rivers)
wrote: In article writes: I appreciate the advice, but as I said before I only have a digital multimeter at my disposal. It sounds like I'd have to bench the amp and connect it up to a tone or sine wave generator to do what you suggest. Am I interpreting you correctly? Well, yes. Your digital multimeter doesn't have an input impedance scale does it? It's not the same as resistance in most cases, in case that's what you were dreaming about. Actually, it pretty much is, in most cases. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#86
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How Do I Determine A Power-Amp's Input Impedance?
On Wed, 14 Jan 2004 10:43:48 -0500, "Ethan Winer" ethanw at
ethanwiner dot com wrote: Stewart, If you don't understand *system* design, then you shouldn't be messing with passives. I guess I just don't see the value of passive audio gear. I appreciate that reducing the number of devices in the chain is always a good idea when all else is equal. But in this case all else is decidely not equal. An active output can drive cables with no HF loss, and the low output impedance reduces or avoids altogether RFI and other interference problems. I have no such problems in my system. An active input can be balanced to reduce hum and RFI. True, but very few domestic hi-fi systems use balanced connections. Further, a passive controller can also be made balanced, indeed Audio Synthesis used to make just such devices, the Passion 8 and ProPassion. Further, the obssession some people have to avoid adding 0.001% distortion seems silly given that all loudspeakers have 100 times more distortion. And any room you're likely to put speakers in has a response that varies by 20-30 dB throughout the entire low end. Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. Which makes it a basic lie - it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. Not to defend Manley. I have no use for tubes either. :-) Actually, they can work extremely well in a pre-amp! :-) -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#87
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How Do I Determine A Power-Amp's Input Impedance?
On Wed, 14 Jan 2004 10:43:48 -0500, "Ethan Winer" ethanw at
ethanwiner dot com wrote: Stewart, If you don't understand *system* design, then you shouldn't be messing with passives. I guess I just don't see the value of passive audio gear. I appreciate that reducing the number of devices in the chain is always a good idea when all else is equal. But in this case all else is decidely not equal. An active output can drive cables with no HF loss, and the low output impedance reduces or avoids altogether RFI and other interference problems. I have no such problems in my system. An active input can be balanced to reduce hum and RFI. True, but very few domestic hi-fi systems use balanced connections. Further, a passive controller can also be made balanced, indeed Audio Synthesis used to make just such devices, the Passion 8 and ProPassion. Further, the obssession some people have to avoid adding 0.001% distortion seems silly given that all loudspeakers have 100 times more distortion. And any room you're likely to put speakers in has a response that varies by 20-30 dB throughout the entire low end. Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. Which makes it a basic lie - it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. Not to defend Manley. I have no use for tubes either. :-) Actually, they can work extremely well in a pre-amp! :-) -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#88
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How Do I Determine A Power-Amp's Input Impedance?
On Wed, 14 Jan 2004 10:43:48 -0500, "Ethan Winer" ethanw at
ethanwiner dot com wrote: Stewart, If you don't understand *system* design, then you shouldn't be messing with passives. I guess I just don't see the value of passive audio gear. I appreciate that reducing the number of devices in the chain is always a good idea when all else is equal. But in this case all else is decidely not equal. An active output can drive cables with no HF loss, and the low output impedance reduces or avoids altogether RFI and other interference problems. I have no such problems in my system. An active input can be balanced to reduce hum and RFI. True, but very few domestic hi-fi systems use balanced connections. Further, a passive controller can also be made balanced, indeed Audio Synthesis used to make just such devices, the Passion 8 and ProPassion. Further, the obssession some people have to avoid adding 0.001% distortion seems silly given that all loudspeakers have 100 times more distortion. And any room you're likely to put speakers in has a response that varies by 20-30 dB throughout the entire low end. Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. Which makes it a basic lie - it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. Not to defend Manley. I have no use for tubes either. :-) Actually, they can work extremely well in a pre-amp! :-) -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#89
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How Do I Determine A Power-Amp's Input Impedance?
On Wed, 14 Jan 2004 10:43:48 -0500, "Ethan Winer" ethanw at
ethanwiner dot com wrote: Stewart, If you don't understand *system* design, then you shouldn't be messing with passives. I guess I just don't see the value of passive audio gear. I appreciate that reducing the number of devices in the chain is always a good idea when all else is equal. But in this case all else is decidely not equal. An active output can drive cables with no HF loss, and the low output impedance reduces or avoids altogether RFI and other interference problems. I have no such problems in my system. An active input can be balanced to reduce hum and RFI. True, but very few domestic hi-fi systems use balanced connections. Further, a passive controller can also be made balanced, indeed Audio Synthesis used to make just such devices, the Passion 8 and ProPassion. Further, the obssession some people have to avoid adding 0.001% distortion seems silly given that all loudspeakers have 100 times more distortion. And any room you're likely to put speakers in has a response that varies by 20-30 dB throughout the entire low end. Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. Which makes it a basic lie - it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. Not to defend Manley. I have no use for tubes either. :-) Actually, they can work extremely well in a pre-amp! :-) -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#90
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How Do I Determine A Power-Amp's Input Impedance?
Yes, no argument there. If I ever changed my system,
I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Which makes it a basic lie -- it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. |
#91
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How Do I Determine A Power-Amp's Input Impedance?
Yes, no argument there. If I ever changed my system,
I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Which makes it a basic lie -- it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. |
#92
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How Do I Determine A Power-Amp's Input Impedance?
Yes, no argument there. If I ever changed my system,
I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Which makes it a basic lie -- it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. |
#93
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How Do I Determine A Power-Amp's Input Impedance?
Yes, no argument there. If I ever changed my system,
I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Which makes it a basic lie -- it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. |
#94
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How Do I Determine A Power-Amp's Input Impedance?
"Ethan Winer" ethanw at ethanwiner dot com wrote in message
I guess I just don't see the value of passive audio gear. Cheap, simple, convenient if used with reasonable care. Case in point the NHTPro PVC. I use one basically because my NHT A10 monitor system power amp has no volume control of its own. Yes, there's a volume control on the sound card I drive it with, but sometimes its just easier to use a real physical volume control than rummage through windows to find the software version. I use my other PVC for odd attenuation needs around the shop. I appreciate that reducing the number of devices in the chain is always a good idea when all else is equal. But in this case all else is decidedly not equal. An active output can drive cables with no HF loss, Not a problem if you put the attenuator reasonably close to the active load. and the low output impedance reduces or avoids altogether RFI and other interference problems. Two words: balanced I/O. An active input can be balanced to reduce hum and RFI. Right, and the A10's power amp has balanced inputs. Further, the obsession some people have to avoid adding 0.001% distortion seems silly given that all loudspeakers have 100 times more distortion. Agreed, OTOH, when I use a PVC to test equipment over a range of input levels, its zero THD feature has some merit. And any room you're likely to put speakers in has a response that varies by 20-30 dB throughout the entire low end. Agreed again. |
#95
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How Do I Determine A Power-Amp's Input Impedance?
"Ethan Winer" ethanw at ethanwiner dot com wrote in message
I guess I just don't see the value of passive audio gear. Cheap, simple, convenient if used with reasonable care. Case in point the NHTPro PVC. I use one basically because my NHT A10 monitor system power amp has no volume control of its own. Yes, there's a volume control on the sound card I drive it with, but sometimes its just easier to use a real physical volume control than rummage through windows to find the software version. I use my other PVC for odd attenuation needs around the shop. I appreciate that reducing the number of devices in the chain is always a good idea when all else is equal. But in this case all else is decidedly not equal. An active output can drive cables with no HF loss, Not a problem if you put the attenuator reasonably close to the active load. and the low output impedance reduces or avoids altogether RFI and other interference problems. Two words: balanced I/O. An active input can be balanced to reduce hum and RFI. Right, and the A10's power amp has balanced inputs. Further, the obsession some people have to avoid adding 0.001% distortion seems silly given that all loudspeakers have 100 times more distortion. Agreed, OTOH, when I use a PVC to test equipment over a range of input levels, its zero THD feature has some merit. And any room you're likely to put speakers in has a response that varies by 20-30 dB throughout the entire low end. Agreed again. |
#96
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How Do I Determine A Power-Amp's Input Impedance?
"Ethan Winer" ethanw at ethanwiner dot com wrote in message
I guess I just don't see the value of passive audio gear. Cheap, simple, convenient if used with reasonable care. Case in point the NHTPro PVC. I use one basically because my NHT A10 monitor system power amp has no volume control of its own. Yes, there's a volume control on the sound card I drive it with, but sometimes its just easier to use a real physical volume control than rummage through windows to find the software version. I use my other PVC for odd attenuation needs around the shop. I appreciate that reducing the number of devices in the chain is always a good idea when all else is equal. But in this case all else is decidedly not equal. An active output can drive cables with no HF loss, Not a problem if you put the attenuator reasonably close to the active load. and the low output impedance reduces or avoids altogether RFI and other interference problems. Two words: balanced I/O. An active input can be balanced to reduce hum and RFI. Right, and the A10's power amp has balanced inputs. Further, the obsession some people have to avoid adding 0.001% distortion seems silly given that all loudspeakers have 100 times more distortion. Agreed, OTOH, when I use a PVC to test equipment over a range of input levels, its zero THD feature has some merit. And any room you're likely to put speakers in has a response that varies by 20-30 dB throughout the entire low end. Agreed again. |
#97
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How Do I Determine A Power-Amp's Input Impedance?
"Ethan Winer" ethanw at ethanwiner dot com wrote in message
I guess I just don't see the value of passive audio gear. Cheap, simple, convenient if used with reasonable care. Case in point the NHTPro PVC. I use one basically because my NHT A10 monitor system power amp has no volume control of its own. Yes, there's a volume control on the sound card I drive it with, but sometimes its just easier to use a real physical volume control than rummage through windows to find the software version. I use my other PVC for odd attenuation needs around the shop. I appreciate that reducing the number of devices in the chain is always a good idea when all else is equal. But in this case all else is decidedly not equal. An active output can drive cables with no HF loss, Not a problem if you put the attenuator reasonably close to the active load. and the low output impedance reduces or avoids altogether RFI and other interference problems. Two words: balanced I/O. An active input can be balanced to reduce hum and RFI. Right, and the A10's power amp has balanced inputs. Further, the obsession some people have to avoid adding 0.001% distortion seems silly given that all loudspeakers have 100 times more distortion. Agreed, OTOH, when I use a PVC to test equipment over a range of input levels, its zero THD feature has some merit. And any room you're likely to put speakers in has a response that varies by 20-30 dB throughout the entire low end. Agreed again. |
#98
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How Do I Determine A Power-Amp's Input Impedance?
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#99
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How Do I Determine A Power-Amp's Input Impedance?
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#101
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How Do I Determine A Power-Amp's Input Impedance?
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#102
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How Do I Determine A Power-Amp's Input Impedance?
On 15 Jan 2004 00:05:42 -0500, (Mike Rivers)
wrote: In article writes: Well, yes. Your digital multimeter doesn't have an input impedance scale does it? It's not the same as resistance in most cases, in case that's what you were dreaming about. Actually, it pretty much is, in most cases. Not when there's a capacitor in series with the input. That will only have effect below 20Hz, and should not have an f3 point above 2Hz. Most multimeters will show a 'flash' reading of the true input resistance, which will then creep higher as the capacitor charges. However, your point is well taken. Personally, I would *never* design an amp with an open capacitor on the input, as this can cause *major* speaker damage if disconnected and reconnected 'hot'. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#103
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How Do I Determine A Power-Amp's Input Impedance?
On 15 Jan 2004 00:05:42 -0500, (Mike Rivers)
wrote: In article writes: Well, yes. Your digital multimeter doesn't have an input impedance scale does it? It's not the same as resistance in most cases, in case that's what you were dreaming about. Actually, it pretty much is, in most cases. Not when there's a capacitor in series with the input. That will only have effect below 20Hz, and should not have an f3 point above 2Hz. Most multimeters will show a 'flash' reading of the true input resistance, which will then creep higher as the capacitor charges. However, your point is well taken. Personally, I would *never* design an amp with an open capacitor on the input, as this can cause *major* speaker damage if disconnected and reconnected 'hot'. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#104
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How Do I Determine A Power-Amp's Input Impedance?
On 15 Jan 2004 00:05:42 -0500, (Mike Rivers)
wrote: In article writes: Well, yes. Your digital multimeter doesn't have an input impedance scale does it? It's not the same as resistance in most cases, in case that's what you were dreaming about. Actually, it pretty much is, in most cases. Not when there's a capacitor in series with the input. That will only have effect below 20Hz, and should not have an f3 point above 2Hz. Most multimeters will show a 'flash' reading of the true input resistance, which will then creep higher as the capacitor charges. However, your point is well taken. Personally, I would *never* design an amp with an open capacitor on the input, as this can cause *major* speaker damage if disconnected and reconnected 'hot'. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#105
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How Do I Determine A Power-Amp's Input Impedance?
On 15 Jan 2004 00:05:42 -0500, (Mike Rivers)
wrote: In article writes: Well, yes. Your digital multimeter doesn't have an input impedance scale does it? It's not the same as resistance in most cases, in case that's what you were dreaming about. Actually, it pretty much is, in most cases. Not when there's a capacitor in series with the input. That will only have effect below 20Hz, and should not have an f3 point above 2Hz. Most multimeters will show a 'flash' reading of the true input resistance, which will then creep higher as the capacitor charges. However, your point is well taken. Personally, I would *never* design an amp with an open capacitor on the input, as this can cause *major* speaker damage if disconnected and reconnected 'hot'. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#106
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How Do I Determine A Power-Amp's Input Impedance?
On Wed, 14 Jan 2004 12:38:58 -0800, "William Sommerwerck"
wrote: Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) Which makes it a basic lie -- it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#107
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How Do I Determine A Power-Amp's Input Impedance?
On Wed, 14 Jan 2004 12:38:58 -0800, "William Sommerwerck"
wrote: Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) Which makes it a basic lie -- it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#108
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How Do I Determine A Power-Amp's Input Impedance?
On Wed, 14 Jan 2004 12:38:58 -0800, "William Sommerwerck"
wrote: Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) Which makes it a basic lie -- it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#109
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How Do I Determine A Power-Amp's Input Impedance?
On Wed, 14 Jan 2004 12:38:58 -0800, "William Sommerwerck"
wrote: Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) Which makes it a basic lie -- it's *not* passive. As Paul explained, a passive device with input and output buffering can still legitimately be considered passive. No, it can't, since the buffering is *active*, and can contribute noise and distortion, just the same as if it had gain. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#110
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How Do I Determine A Power-Amp's Input Impedance?
Yes, no argument there. If I ever changed my system,
I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) I considered "system" to be sufficiently ambiguous to justify my comment. Yes, orthodynamic speakers are pretty much resistive, but Divas are not the sort of speaker you drive with an integrated amp -- just on general principles. They "deserve" separates, if only for reasons of snobbishness. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. I was using EQ as a generic term for a change in frequency response (which includes crossover functions). The Vendetta moving-coil preamp (which brings the signal up to line level) uses passive EQ for the HF equalization, followed by active EQ for LF. John Curl told me he had a hell of time getting the first stage quiet enough without feedback. But you can turn the volume control on the amp following the Vendetta "all the way to 11" and only a little bit of hiss is audible. |
#111
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How Do I Determine A Power-Amp's Input Impedance?
Yes, no argument there. If I ever changed my system,
I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) I considered "system" to be sufficiently ambiguous to justify my comment. Yes, orthodynamic speakers are pretty much resistive, but Divas are not the sort of speaker you drive with an integrated amp -- just on general principles. They "deserve" separates, if only for reasons of snobbishness. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. I was using EQ as a generic term for a change in frequency response (which includes crossover functions). The Vendetta moving-coil preamp (which brings the signal up to line level) uses passive EQ for the HF equalization, followed by active EQ for LF. John Curl told me he had a hell of time getting the first stage quiet enough without feedback. But you can turn the volume control on the amp following the Vendetta "all the way to 11" and only a little bit of hiss is audible. |
#112
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How Do I Determine A Power-Amp's Input Impedance?
Yes, no argument there. If I ever changed my system,
I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) I considered "system" to be sufficiently ambiguous to justify my comment. Yes, orthodynamic speakers are pretty much resistive, but Divas are not the sort of speaker you drive with an integrated amp -- just on general principles. They "deserve" separates, if only for reasons of snobbishness. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. I was using EQ as a generic term for a change in frequency response (which includes crossover functions). The Vendetta moving-coil preamp (which brings the signal up to line level) uses passive EQ for the HF equalization, followed by active EQ for LF. John Curl told me he had a hell of time getting the first stage quiet enough without feedback. But you can turn the volume control on the amp following the Vendetta "all the way to 11" and only a little bit of hiss is audible. |
#113
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How Do I Determine A Power-Amp's Input Impedance?
Yes, no argument there. If I ever changed my system,
I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) I considered "system" to be sufficiently ambiguous to justify my comment. Yes, orthodynamic speakers are pretty much resistive, but Divas are not the sort of speaker you drive with an integrated amp -- just on general principles. They "deserve" separates, if only for reasons of snobbishness. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. I was using EQ as a generic term for a change in frequency response (which includes crossover functions). The Vendetta moving-coil preamp (which brings the signal up to line level) uses passive EQ for the HF equalization, followed by active EQ for LF. John Curl told me he had a hell of time getting the first stage quiet enough without feedback. But you can turn the volume control on the amp following the Vendetta "all the way to 11" and only a little bit of hiss is audible. |
#114
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How Do I Determine A Power-Amp's Input Impedance?
"William Sommerwerck" wrote in message
Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) Right. 4 ohm mostly resistive with is common with ribbons and 4 ohms way reactive which is common with moving-coil speakers are two different things. The resistor is way too easy, which is why I test amps with a loudspeaker simulator that tries to be highly reactive and have low impedance magnitude in the same frequency ranges. I considered "system" to be sufficiently ambiguous to justify my comment. Yes, orthodynamic speakers are pretty much resistive, but Divas are not the sort of speaker you drive with an integrated amp -- just on general principles. They "deserve" separates, if only for reasons of snobbishness. Hold that thought: "snobbishness". The hidden agenda in power amp design is the nature of music signals themselves. The peak-to-average ratios are 8 dB or more even for highly-compressed, highly clipped so-called music. By law in the US we rate consumer home stereo amps with signals that have a peak-to-average ratio of 0 dB. That means that by law just about all amps, even $79 100 wpc receivers, are wildly overbuilt if used with even a modicum of common sense. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. That's one way to look at it. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. I was using EQ as a generic term for a change in frequency response (which includes crossover functions). I think we all agree that EQ also includes pre-emphasis and de-emphasis. The Vendetta moving-coil preamp (which brings the signal up to line level) uses passive EQ for the HF equalization, followed by active EQ for LF. John Curl told me he had a hell of time getting the first stage quiet enough without feedback. You're preaching to the choir here. If you searched google you'd find a number of posts from Pinkerton alluding to the same issue. You'd also find a link to a very nice schematic of his personal phono preamp. 20 dB of passive Eq applied to a pre-emphasized signal that tends to rise in amplitude often implies some fairly significant sacrifices in terms of dynamic range. On balance, the vinyl record itself is usually if not always so noisy that handling signals derived from it with modern electronics is usually not much of a serious challenge. Things get a little dicier with low-output MC cartridges, but IMO that's a case of unnecessarily trying to make things hard for yourself. But you can turn the volume control on the amp following the Vendetta "all the way to 11" and only a little bit of hiss is audible. Lat time I looked, "all the way" was more like 5 o'clock. Is the Vendetta volume control mounted oddly? |
#115
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How Do I Determine A Power-Amp's Input Impedance?
"William Sommerwerck" wrote in message
Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) Right. 4 ohm mostly resistive with is common with ribbons and 4 ohms way reactive which is common with moving-coil speakers are two different things. The resistor is way too easy, which is why I test amps with a loudspeaker simulator that tries to be highly reactive and have low impedance magnitude in the same frequency ranges. I considered "system" to be sufficiently ambiguous to justify my comment. Yes, orthodynamic speakers are pretty much resistive, but Divas are not the sort of speaker you drive with an integrated amp -- just on general principles. They "deserve" separates, if only for reasons of snobbishness. Hold that thought: "snobbishness". The hidden agenda in power amp design is the nature of music signals themselves. The peak-to-average ratios are 8 dB or more even for highly-compressed, highly clipped so-called music. By law in the US we rate consumer home stereo amps with signals that have a peak-to-average ratio of 0 dB. That means that by law just about all amps, even $79 100 wpc receivers, are wildly overbuilt if used with even a modicum of common sense. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. That's one way to look at it. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. I was using EQ as a generic term for a change in frequency response (which includes crossover functions). I think we all agree that EQ also includes pre-emphasis and de-emphasis. The Vendetta moving-coil preamp (which brings the signal up to line level) uses passive EQ for the HF equalization, followed by active EQ for LF. John Curl told me he had a hell of time getting the first stage quiet enough without feedback. You're preaching to the choir here. If you searched google you'd find a number of posts from Pinkerton alluding to the same issue. You'd also find a link to a very nice schematic of his personal phono preamp. 20 dB of passive Eq applied to a pre-emphasized signal that tends to rise in amplitude often implies some fairly significant sacrifices in terms of dynamic range. On balance, the vinyl record itself is usually if not always so noisy that handling signals derived from it with modern electronics is usually not much of a serious challenge. Things get a little dicier with low-output MC cartridges, but IMO that's a case of unnecessarily trying to make things hard for yourself. But you can turn the volume control on the amp following the Vendetta "all the way to 11" and only a little bit of hiss is audible. Lat time I looked, "all the way" was more like 5 o'clock. Is the Vendetta volume control mounted oddly? |
#116
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How Do I Determine A Power-Amp's Input Impedance?
"William Sommerwerck" wrote in message
Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) Right. 4 ohm mostly resistive with is common with ribbons and 4 ohms way reactive which is common with moving-coil speakers are two different things. The resistor is way too easy, which is why I test amps with a loudspeaker simulator that tries to be highly reactive and have low impedance magnitude in the same frequency ranges. I considered "system" to be sufficiently ambiguous to justify my comment. Yes, orthodynamic speakers are pretty much resistive, but Divas are not the sort of speaker you drive with an integrated amp -- just on general principles. They "deserve" separates, if only for reasons of snobbishness. Hold that thought: "snobbishness". The hidden agenda in power amp design is the nature of music signals themselves. The peak-to-average ratios are 8 dB or more even for highly-compressed, highly clipped so-called music. By law in the US we rate consumer home stereo amps with signals that have a peak-to-average ratio of 0 dB. That means that by law just about all amps, even $79 100 wpc receivers, are wildly overbuilt if used with even a modicum of common sense. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. That's one way to look at it. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. I was using EQ as a generic term for a change in frequency response (which includes crossover functions). I think we all agree that EQ also includes pre-emphasis and de-emphasis. The Vendetta moving-coil preamp (which brings the signal up to line level) uses passive EQ for the HF equalization, followed by active EQ for LF. John Curl told me he had a hell of time getting the first stage quiet enough without feedback. You're preaching to the choir here. If you searched google you'd find a number of posts from Pinkerton alluding to the same issue. You'd also find a link to a very nice schematic of his personal phono preamp. 20 dB of passive Eq applied to a pre-emphasized signal that tends to rise in amplitude often implies some fairly significant sacrifices in terms of dynamic range. On balance, the vinyl record itself is usually if not always so noisy that handling signals derived from it with modern electronics is usually not much of a serious challenge. Things get a little dicier with low-output MC cartridges, but IMO that's a case of unnecessarily trying to make things hard for yourself. But you can turn the volume control on the amp following the Vendetta "all the way to 11" and only a little bit of hiss is audible. Lat time I looked, "all the way" was more like 5 o'clock. Is the Vendetta volume control mounted oddly? |
#117
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How Do I Determine A Power-Amp's Input Impedance?
"William Sommerwerck" wrote in message
Yes, no argument there. If I ever changed my system, I'd like as not use a modern integrated amplifier. To drive Apogee Divas? Thou jesteth. Note that I said change the *system*. BTW, Divas are a pretty much resistive 4 ohm load, not nearly so difficult to drive as many modern boxes. There's so much mythology in 'high end' audio! :-) Right. 4 ohm mostly resistive with is common with ribbons and 4 ohms way reactive which is common with moving-coil speakers are two different things. The resistor is way too easy, which is why I test amps with a loudspeaker simulator that tries to be highly reactive and have low impedance magnitude in the same frequency ranges. I considered "system" to be sufficiently ambiguous to justify my comment. Yes, orthodynamic speakers are pretty much resistive, but Divas are not the sort of speaker you drive with an integrated amp -- just on general principles. They "deserve" separates, if only for reasons of snobbishness. Hold that thought: "snobbishness". The hidden agenda in power amp design is the nature of music signals themselves. The peak-to-average ratios are 8 dB or more even for highly-compressed, highly clipped so-called music. By law in the US we rate consumer home stereo amps with signals that have a peak-to-average ratio of 0 dB. That means that by law just about all amps, even $79 100 wpc receivers, are wildly overbuilt if used with even a modicum of common sense. You guys are confusing the device with the transfer function. If the EQ is obtained by a device outside the feedback loop, then it is passive EQ. That's one way to look at it. No one is talking about EQ. You are clearly talking about phono stages, where passive HF EQ can indeed be beneficial, but that's another story. I was using EQ as a generic term for a change in frequency response (which includes crossover functions). I think we all agree that EQ also includes pre-emphasis and de-emphasis. The Vendetta moving-coil preamp (which brings the signal up to line level) uses passive EQ for the HF equalization, followed by active EQ for LF. John Curl told me he had a hell of time getting the first stage quiet enough without feedback. You're preaching to the choir here. If you searched google you'd find a number of posts from Pinkerton alluding to the same issue. You'd also find a link to a very nice schematic of his personal phono preamp. 20 dB of passive Eq applied to a pre-emphasized signal that tends to rise in amplitude often implies some fairly significant sacrifices in terms of dynamic range. On balance, the vinyl record itself is usually if not always so noisy that handling signals derived from it with modern electronics is usually not much of a serious challenge. Things get a little dicier with low-output MC cartridges, but IMO that's a case of unnecessarily trying to make things hard for yourself. But you can turn the volume control on the amp following the Vendetta "all the way to 11" and only a little bit of hiss is audible. Lat time I looked, "all the way" was more like 5 o'clock. Is the Vendetta volume control mounted oddly? |
#118
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How Do I Determine A Power-Amp's Input Impedance?
Arny,
Cheap, simple, convenient if used with reasonable care. My first "passive volume control" was 30-40 years ago, when I bought a four-input Radio Shack passive mixer. Remember those? It was great for the time, and my budget back then. An active output can drive cables with no HF loss Not a problem if you put the attenuator reasonably close to the active load. Agreed. I just bought a Jensen transformer for my subwoofer, and they too made the point that the transformer should be at the subwoofer end of the wire. when I use a PVC to test equipment over a range of input levels, its zero THD feature has some merit. Yes, since you do professional testing I agree. Then again, I don't think most audiophiles do much testing! --Ethan |
#119
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How Do I Determine A Power-Amp's Input Impedance?
Arny,
Cheap, simple, convenient if used with reasonable care. My first "passive volume control" was 30-40 years ago, when I bought a four-input Radio Shack passive mixer. Remember those? It was great for the time, and my budget back then. An active output can drive cables with no HF loss Not a problem if you put the attenuator reasonably close to the active load. Agreed. I just bought a Jensen transformer for my subwoofer, and they too made the point that the transformer should be at the subwoofer end of the wire. when I use a PVC to test equipment over a range of input levels, its zero THD feature has some merit. Yes, since you do professional testing I agree. Then again, I don't think most audiophiles do much testing! --Ethan |
#120
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How Do I Determine A Power-Amp's Input Impedance?
Arny,
Cheap, simple, convenient if used with reasonable care. My first "passive volume control" was 30-40 years ago, when I bought a four-input Radio Shack passive mixer. Remember those? It was great for the time, and my budget back then. An active output can drive cables with no HF loss Not a problem if you put the attenuator reasonably close to the active load. Agreed. I just bought a Jensen transformer for my subwoofer, and they too made the point that the transformer should be at the subwoofer end of the wire. when I use a PVC to test equipment over a range of input levels, its zero THD feature has some merit. Yes, since you do professional testing I agree. Then again, I don't think most audiophiles do much testing! --Ethan |
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