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Post by mgbpuff on Sept 26, 2020 10:16:26 GMT -5
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Post by knucklehead on Sept 26, 2020 11:40:36 GMT -5
From that article:
Emotiva XPA-2 Gen3: $999 (two-channel version) $$$
The XPA Gen3 is a modular class-H amplifier—its input stage tells its power-supply stage when and when not to stoke the fires of its output stage—but it isn't just a stereo amp: it can be ordered with anywhere from two to seven channels. (The two-channel version costs $999; each additional channel adds $200 to the price. Channels can be added only by Emotiva or an authorized Emotiva dealer.) HR tried a two-channel XPA Gen3—300Wpc into 8 ohms, 550Wpc into 4 ohms—with a variety of different speakers. The pairing with Zu Soul Supremes was less than dreamy, but listening to Miles Davis through the hard-to-drive Magnepan .7s, Herb wrote that "the bell of his trumpet was right there in front of me," and observed that the Emotiva "held and guided the Magnepan .7s with almost a lover's touch: not too tight, not too loose." Then again, through the Technics SB-C700S speakers, the sound of the Emotiva had HR reaching for words like "hard" and "transistor sound." In measuring the XPA Gen3, JA discovered that the percentage of THD+N climbed "precipitously" above 15kHz, though he acknowledged that it offered very high power "at a very affordable price." (Vol.40 No.8 WWW)
I highlited that one phrase, of all the flowery prose I've read over the years that audio reviewers have used, I thought I'd heard it all. I guess I should quit saying "I've heard it all now."
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Deleted
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Post by Deleted on Sept 26, 2020 15:43:09 GMT -5
From that article: Emotiva XPA-2 Gen3: $999 (two-channel version) $$$The XPA Gen3 is a modular class-H amplifier—its input stage tells its power-supply stage when and when not to stoke the fires of its output stage—but it isn't just a stereo amp: it can be ordered with anywhere from two to seven channels. (The two-channel version costs $999; each additional channel adds $200 to the price. Channels can be added only by Emotiva or an authorized Emotiva dealer.) HR tried a two-channel XPA Gen3—300Wpc into 8 ohms, 550Wpc into 4 ohms—with a variety of different speakers. The pairing with Zu Soul Supremes was less than dreamy, but listening to Miles Davis through the hard-to-drive Magnepan .7s, Herb wrote that "the bell of his trumpet was right there in front of me," and observed that the Emotiva "held and guided the Magnepan .7s with almost a lover's touch: not too tight, not too loose." Then again, through the Technics SB-C700S speakers, the sound of the Emotiva had HR reaching for words like "hard" and "transistor sound." In measuring the XPA Gen3, JA discovered that the percentage of THD+N climbed "precipitously" above 15kHz, though he acknowledged that it offered very high power "at a very affordable price." (Vol.40 No.8 WWW) I highlited that one phrase, of all the flowery prose I've read over the years that audio reviewers have used, I thought I'd heard it all. I guess I should quit saying "I've heard it all now." I "almost" enjoyed that! Meh, could of been better or could of been worse. |
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Post by leonski on Sept 27, 2020 16:16:14 GMT -5
Maybe good news for Magnepan owners?
No assigned reason for the rise in THD, though maybe the switcher is intruding here? What kind of filter is used to get rid of the switching noise?
Also, what IS the switching frequency? And while I'm at it? Any word on Dynamic Headroomm?? Or does that switcher top out and that's IT?
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Post by Cogito on Sept 27, 2020 20:57:11 GMT -5
Maybe good news for Magnepan owners? No assigned reason for the rise in THD, though maybe the switcher is intruding here? What kind of filter is used to get rid of the switching noise? Also, what IS the switching frequency? And while I'm at it? Any word on Dynamic Headroomm?? Or does that switcher top out and that's IT? Switching power supplies typically don't have much headroom. ANOTHER reason not to use them in power amps. |
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Post by leonski on Sept 27, 2020 23:12:14 GMT -5
Maybe good news for Magnepan owners? No assigned reason for the rise in THD, though maybe the switcher is intruding here? What kind of filter is used to get rid of the switching noise? Also, what IS the switching frequency? And while I'm at it? Any word on Dynamic Headroomm?? Or does that switcher top out and that's IT? Switching power supplies typically don't have much headroom. ANOTHER reason not to use them in power amps. Yep.....That's why I ASKED. Very low stored energy in such a PS means little headroom.....That's why I'm STILL a fan of conventional PS......and simplicity. |
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cawgijoe
Emo VIPs 
"When you come to a fork in the road, take it." - Yogi Berra
Posts: 5,033
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Post by cawgijoe on Sept 28, 2020 6:17:06 GMT -5
Maybe good news for Magnepan owners? No assigned reason for the rise in THD, though maybe the switcher is intruding here? What kind of filter is used to get rid of the switching noise? Also, what IS the switching frequency? And while I'm at it? Any word on Dynamic Headroomm?? Or does that switcher top out and that's IT? Switching power supplies typically don't have much headroom. ANOTHER reason not to use them in power amps. Just from my experience, not comparing the technology, my current XPA-5 Gen 3 sounds better to my ears than the XPA-5 Gen 1 I owned. There is plenty of headroom using my Thiel speakers....CS1.6 and SCS3. It's not a huge difference, but I find the new Gen to be clearer and more defined. |
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Post by rbk123 on Sept 28, 2020 8:04:24 GMT -5
They don't need much headroom. Their architecture is such that they are so fast, they generate the needed power instantly instead of having to rely on capacitor reserves. Their "headroom" is built into their design. It can be good or it can be bad depending on how it's integrated with the rest of the design. Emo did it more than correctly so I wouldn't worry about it, or at least not worry about this attribute.
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Post by mgbpuff on Sept 28, 2020 10:46:28 GMT -5
They don't need much headroom. Their architecture is such that they are so fast, they generate the needed power instantly instead of having to rely on capacitor reserves. Their "headroom" is built into their design. It can be good or it can be bad depending on how it's integrated with the rest of the design. Emo did it more than correctly so I wouldn't worry about it, or at least not worry about this attribute. I am a believer in the isolation provided by a transformer. Also the instantaneous energy stored in a conventional power supply can be several times above that of instantaneous direct current delivery from a 15 amp household circuit. |
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Post by rbk123 on Sept 28, 2020 10:57:25 GMT -5
That's why SMPS's have some capacitance, just nowhere near as much as torroids. It's part of that "implemented correctly" thing I mentioned....
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Post by Deleted on Sept 28, 2020 11:04:03 GMT -5
Boulder Amplifier, "Boulder's 2050 monoblock, introduced in 2000—is among those relatively recent designs that operate in class-A for their full rated power, yet do so by means of microprocessor-based circuits that continually adjust bias in response to current draw, load, and other parameters. Consequently, the 2150 runs relatively cool. Each 2150 uses global feedback (proudly: its manufacturer suggests that manufacturers who don't use feedback simply don't know how to do so properly), boasts an output section containing 80 bipolar devices, requires an AC cord compatible with its 32A IEC socket, has heatsinks machined into the sides of its chassis, and weighs an extraordinary 220lb (319lb in its shipping crate). For all that bigness, the Boulder amp kept out of MF's way, sonically: "It was about as tonally neutral a piece of electronics as I've heard here, neither warm nor cool." MF also praised the Boulder's "unrestricted microdynamic excursions" and its "well-controlled, ultra-solid, well-defined low-frequency response."
I enjoyed this......... I realize we're comparing a Ferrari to .......... a lemon but nevertheless enjoyed the company's response.
Being a newfound Parasound "fanboy" I also enjoyed seeing TWO Parasounds make this list without compromising "fidelity for price point", a characteristic the Emotiva was mentioned as having [Paraphrasing] to even get onto the list.
Class A ......... to me is most desirable.
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Post by mgbpuff on Sept 28, 2020 11:52:14 GMT -5
That's why SMPS's have some capacitance, just nowhere near as much as torroids. It's part of that "implemented correctly" thing I mentioned.... It's like the difference between a hose and a water tower. |
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Post by rbk123 on Sept 28, 2020 12:09:39 GMT -5
Um yeah, when it comes to amp performance - not so much.
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Post by leonski on Sept 29, 2020 18:25:50 GMT -5
That's why SMPS's have some capacitance, just nowhere near as much as torroids. It's part of that "implemented correctly" thing I mentioned.... It's like the difference between a hose and a water tower. that's the 'TRICK' of a switcher. First? a Capacitor.....is one of the basic building blocks of ALL circuits. Crossovers in speakers, for example use Capacitors, Inductors and Resistors......3 elementary components. Switchers V linear? Switchers operate at quite high frequencies. 100khz? 200khz? 400khz? and higher. So the capacitors get to recharge a LOT MORE OFTEN. A linear supply only recharges at line frequency of 50hz or 60hz. And than, only when the capacitor drops BELOW PS voltage. THATS where switchers have a theoretical advantage. But you must get rid of the frequency from the PS and they have poor dynamic power.......continuous is IT. To go back to the hose? You can either have a huge water tower (big PS caps) OR a small bucket from which you refill the hose instantly. At the other end? should be tough to tell the difference. |
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Post by mgbpuff on Sept 30, 2020 8:17:53 GMT -5
It's like the difference between a hose and a water tower. that's the 'TRICK' of a switcher. First? a Capacitor.....is one of the basic building blocks of ALL circuits. Crossovers in speakers, for example use Capacitors, Inductors and Resistors......3 elementary components. Switchers V linear? Switchers operate at quite high frequencies. 100khz? 200khz? 400khz? and higher. So the capacitors get to recharge a LOT MORE OFTEN. A linear supply only recharges at line frequency of 50hz or 60hz. And than, only when the capacitor drops BELOW PS voltage. THATS where switchers have a theoretical advantage. But you must get rid of the frequency from the PS and they have poor dynamic power.......continuous is IT. To go back to the hose? You can either have a huge water tower (big PS caps) OR a small bucket from which you refill the hose instantly. At the other end? should be tough to tell the difference. The linear ps with it's huge capacitive storage, breaks the direct link to the utility line with all its noises and micro drop outs and spikes. It also is capable of higher instantaneous power delivery. I'll take the old fashioned path. |
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Post by rbk123 on Sept 30, 2020 10:04:24 GMT -5
It doesn't "break the link" since it doesn't draw on the capacitance every time, that's only for when needed by the source material, not the power company. Powerline noise doesn't get filtered by the power supply capacitors; if it did the amp wouldn't be susceptible to brown outs and all other issues that torroids and their capacitors do nothing to prevent. However none of this matters as it's just classic audiophools doing armchair engineering. The only thing that matters is the end result and how does it sound. If it doesn't sound better then other amps, then people won't buy it, however clearly these are fine sounding amps.
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Post by mgbpuff on Sept 30, 2020 10:24:33 GMT -5
It doesn't "break the link" since it doesn't draw on the capacitance every time, that's only for when needed by the source material, not the power company. Powerline noise doesn't get filtered by the power supply capacitors; if it did the amp wouldn't be susceptible to brown outs and all other issues that torroids and their capacitors do nothing to prevent. However none of this matters as it's just classic audiophools doing armchair engineering. The only thing that matters is the end result and how does it sound. If it doesn't sound better then other amps, then people won't buy it, however clearly these are fine sounding amps. Fist by definition isolation transformers isolate. Second capacitors store charge (you know, those little invisible particles called electrons). The amount of storage is small but more than enough to supply up to four times the instantaneous power of a direct line and more than enough to obscure (o.K. filter) many small line disturbances. SMPS introduce high frequency noise (a lot). but they are cheap cheap cheap and that is their attraction. If you want to protect against brown outs, you need a lot more storage, not less. You need an uninterruptable power supple with battery storage. |
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Post by rbk123 on Sept 30, 2020 12:39:04 GMT -5
First isolation transforms isolate the circuitry - this is for grounding and other electrical purposes. The torroid is simply a stepping (up/down/even) function, however whatever amplitude changes come into it (line noise) also get passed on to the windings of the 2nd stage.
Second, any filtering of those little invisible particles called electrons, performed by the capacitors is post torroid stage. This means that an SMPS can also utilize filtering capacitors, for you know those little invisible particles called electrons, as well - and surprise, they do. The goal of BOTH power supply designs is to provide as straight a line of DC power as possible; they want to appear like a battery.
Third, SMPS's *can* introduce high frequency noise but that depends on the design.
Of course you need a UPS for brown out protection, just pointing out the absurdity of your prior hair-brained idea that a torroid based power supply protects against "utility line noises". You really need to give it a rest.
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Post by leonski on Sept 30, 2020 14:31:52 GMT -5
I use an external device for low AND high voltage protection. My power will shut down OVER about 135v and BELOW about 95v on the 'incoming'.....
I've seen several 'Scope images of 10khz aquare wave amp output with a 'sawtooth' riding along. Counting the bumps and doing the math gives a good idea of the switching frequency of the PS.
A brownout is not exactly noise. And transfromers will not pass certain crumby stuff from the powerline into the circuit in question. I have a 400va Isolation transformer into which my low current stuff plugs. VERY quiet.
When I first hooked this up, I had a CRT televsion. Virtually all the snow disappeared. Colors and contrast, as a result, improved dramatically.
An iso transformer is a special case with 1:1 windings ratio with other properties shared with the rest of the toroid line.
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Post by rbk123 on Sept 30, 2020 18:45:09 GMT -5
An iso transformer is a special case with 1:1 windings ratio with other properties shared with the rest of the toroid line. Exactly - they have no step up or down, they're the "even" I mentioned. I guarantee you the Puffster doesn't own a single amp that has an isolation transformer in it. I don't think one has ever been made with one, but I suppose there may be some extremely rare model out there. |
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