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Post by Deleted on Feb 6, 2023 15:18:04 GMT -5
I read the Stereophile article...way above my head. Here are the specs for the OSD amp. Good enough for B&w 702 LCR? I like the idea of combing the OSD Nero Amp with the MR1 driving the rest of my speakers (SVS prime elevation) Amplifier Class: Class H Channels/Zones: 3 Channels Power Output @ 8 Ohm: 165W RMS per Channel Power Output @ 4 Ohm: 260W RMS per Channel Frequency Response: 7.5Hz to 80kHz +/-0.5dB Impedance: 8 Ohm and 4 Ohm Stable Transformer Type: .9 KVA toroidal Inputs: XLR / RCA Outputs: 4 per channel Capacitors, number & size: 6800uf&12pcs The lack of a straight answer from anyone on how this amp or the MR-1 will perform with the 702s is due to the subjective nature of any response. System synergy is tricky and specs don’t tell the story. Only you can decide if it sounds good to you. I think the MR-1 does a great job driving the 702s, but I also think a sub is a necessity as the S2s really just do not have a full bottom end IMO (something B&W rectified with the new S3). That’s me. You might think otherwise and that’s great. The only thing you can do to get a real answer is buy the MR-1 and try it. |
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Post by creimes on Feb 6, 2023 15:43:48 GMT -5
I read the Stereophile article...way above my head. Here are the specs for the OSD amp. Good enough for B&w 702 LCR? I like the idea of combing the OSD Nero Amp with the MR1 driving the rest of my speakers (SVS prime elevation) Amplifier Class: Class H Channels/Zones: 3 Channels Power Output @ 8 Ohm: 165W RMS per Channel Power Output @ 4 Ohm: 260W RMS per Channel Frequency Response: 7.5Hz to 80kHz +/-0.5dB Impedance: 8 Ohm and 4 Ohm Stable Transformer Type: .9 KVA toroidal Inputs: XLR / RCA Outputs: 4 per channel Capacitors, number & size: 6800uf&12pcs The lack of a straight answer from anyone on how this amp or the MR-1 will perform with the 702s is due to the subjective nature of any response. System synergy is tricky and specs don’t tell the story. Only you can decide if it sounds good to you. I think the MR-1 does a great job driving the 702s, but I also think a sub is a necessity as the S2s really just do not have a full bottom end IMO (something B&W rectified with the new S3). That’s me. You might think otherwise and that’s great. The only thing you can do to get a real answer is buy the MR-1 and try it. This is where the 30 day trial comes in handy, try it in your room to your ears with your gear and see hear what you think |
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Post by leonski on Feb 6, 2023 17:37:15 GMT -5
The ONLY red flag, Bernie? Amp class 'H' is not a class but rather a power supply design. I don't know exactly....but it is either a PS with 'rails' in which the amp cruises most of the time with say.....a 20 or 30 volt rail. When a peak comes along? Amp automatically switches to 50 or maybe higher for the 'other' and higher rail voltage. I think EMO does the same thing. OR it is a 'tracking' PS, the philosophical son of what Carver did many years ago, starting with his Carver t-mod amps.... This constantly adjusts the PS to match the music. My Carver Cube did this and would dim the lights in the house at the highest peaks....This was the M400t which had a 15amp power fuse (a lot) and 'only' 200x2 8 ohm watts..... www.psiaudio.swiss/faq-items/vivamus-ullamcorper-nim-sit-amet-consequat-laoreet-tortor-tortor-dictum-egestas-urna/In any event? Amp has reasonable specs. BUT, must wait for a listening evaluation. It is possible for such a PS to create some noise due to the artifacts of how it works.... Listen to Bernie about 'testing before buying'.....A very good idea. |
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Post by KeithL on Feb 6, 2023 23:02:59 GMT -5
Most speaker designers I know would say that, if a speaker has an impedance of 3.1 Ohms, over a significant portion of the frequency range, then it should be considered to be a 4 Ohm speaker. (In general "a well behaved speaker shouldn't drop much below about 3/4 of its rated impedance"... )
But, since that isn't a problem either way for the MR1, or for any of our amps, it doesn't really matter. (Although, yes, I guess some really anemic AVRs might have trouble with it.  ) www.stereophile.com/content/bowers-wilkins-702-s2-loudspeaker-measurementsSpeaker is fairly sensitivy at about 90db. But does drop to 3.1 ohms on an 8 ohm 'nominal' rating. Stereophile liked 'em with the A31.....2 channels of which are basically an A21 of 250x2 @8 ohms. In a small room? You probably won't need that kind of 'ooomph' but be able to make do with 1/2 that or so. Call it 3db less power. The A23 might work, if you like the Parasound presentation.... Read the review to get some idea what and WHY the reviewer makes the choices he makes..... He also recommends using an amp with strong 4 ohm ratings. IMO? You might want to consider a good power and low distortion at the lower impedance rating..... I would ALSO suggest that few if Any HT amps or 'integrateds' (like the mr1) need apply...... |
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Post by KeithL on Feb 6, 2023 23:10:54 GMT -5
Here's the catch there....
Because music is dynamic, unless you're literally playing really long pipe organ notes, an amplifier will NEVER be asked to deliver anywhere near full power, from even one channel, for very long. Because normal music is dynamic, if you play it "as loud as you can without clipping the peaks", the average power you're using is usually between 1/10 and 1/20 of rated full power. So, in real life, most of the time, you've got, at most, one or two channels, delivering full rated power, for a small fraction of a second.
(And, if you really are playing sustained pipe organ notes, at full rated power, you should really be using a sub for that... because, among other things, that will warm up regular woofers pretty quickly.)
So, while we do include the "4 Ohms - all channels driven" rating on the MR1...
Unless you're "using it to light bulbs or heat up resistors" the "two channels driven" and even "five channels driven" numbers matter much more. Question about the power rating on the three front channels. Page 18 of the manual states: "...The amplifiers powering the front three channels feature a special high-current output stage for exceptional sound stage coherence and clarity." Are the 3 front channels rated at a higher watt per channel than the surrounds? 165 watts for each front 3 and 100 watts for each of the 8 surrounds? In any event, rated power will drop like a stone when all channels are in play. Even if not at 'full tilt', I'd expect a 20% power reduction to start. More as demand rises.... And power / distortion at 4ohms also comes into play, if even so rated. |
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Post by Deleted on Feb 6, 2023 23:26:18 GMT -5
After a good hard reboot of the AppleTV, the MR-1 and the AppleTV seem to be playing nicely with one another on HDMI 1. Haven't watched a ton of content, but it has been mixed and no issues have cropped up. Thanks again doc1963 for the suggestion. Can't believe I didn't think of it  |
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Post by akcorr on Feb 6, 2023 23:55:40 GMT -5
After a good hard reboot of the AppleTV, the MR-1 and the AppleTV seem to be playing nicely with one another on HDMI 1. Haven't watched a ton of content, but it has been mixed and no issues have cropped up. Thanks again doc1963 for the suggestion. Can't believe I didn't think of it Really good info there to keep in mind when mine arrives! Did not know that about the EDID and a cold boot but it makes sense! |
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Post by leonski on Feb 7, 2023 13:26:03 GMT -5
Here's the catch there....
Because music is dynamic, unless you're literally playing really long pipe organ notes, an amplifier will NEVER be asked to deliver anywhere near full power, from even one channel, for very long. Because normal music is dynamic, if you play it "as loud as you can without clipping the peaks", the average power you're using is usually between 1/10 and 1/20 of rated full power. So, in real life, most of the time, you've got, at most, one or two channels, delivering full rated power, for a small fraction of a second.
(And, if you really are playing sustained pipe organ notes, at full rated power, you should really be using a sub for that... because, among other things, that will warm up regular woofers pretty quickly.)
So, while we do include the "4 Ohms - all channels driven" rating on the MR1...
Unless you're "using it to light bulbs or heat up resistors" the "two channels driven" and even "five channels driven" numbers matter much more. In any event, rated power will drop like a stone when all channels are in play. Even if not at 'full tilt', I'd expect a 20% power reduction to start. More as demand rises.... And power / distortion at 4ohms also comes into play, if even so rated. Yes. Usual 'crest factor'.....the ratio of peak to average, is usually either considered to be 10 db or 20 db.....In general NOT a big deal except when you own lower than average sensitivity speakers and a combination of liking it LOUD and having larger space (cubic, not square feet or meters) So? With a 10db crest factor, you can be cruising along a 5 watts and instantly need 50.......for a short time period. That's at 10db.....20db gets a LOT worse, fairly quickly. from our truth in advertising department? 5 watts is LOUD...... My 4 ohm remark will stand. I'm always a little leery of any amp rated at 1% distortion. That's a red-flag for 'low headroom'....at least at higher distortion. The good news with THAT is nobody knows what most of those movie effects sound like, anyway..... |
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Post by Deleted on Feb 7, 2023 22:21:32 GMT -5
Does any of the Emotiva gear have signal sensing on either the coax digital or USB inputs to turn on? Want to add a Roon streamer, but don’t want to have to turn on the MR-1 separately.
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Post by leonski on Feb 8, 2023 1:48:25 GMT -5
Really? That a deal breaker? Or just something you'd like to have included?
Either is OK, but there IS something like a Logitech remote which in my case turns on TV, Preamp and Small Dish receiver. I have to turn on the optic switch with ITS remote.....
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Post by Deleted on Feb 8, 2023 8:26:53 GMT -5
Really? That a deal breaker? Or just something you'd like to have included? Either is OK, but there IS something like a Logitech remote which in my case turns on TV, Preamp and Small Dish receiver. I have to turn on the optic switch with ITS remote..... No, it was just a question. If the processors had that feature I might consider upgrading. As for the Harmony, it does not work in this case as I was considering adding a Blusound Node. Roon capability isn't a necessity, but I use it extensively around the house and while my AppleTV can act as an endpoint when I go to use it the TV comes on too since I have CEC control turned on. |
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Post by KeithL on Feb 8, 2023 13:20:34 GMT -5
I wanted to weigh in here on your last comment... about rating things at 1% THD. The simple fact is that, with almost all modern solid state designs, including ours, this works out a bit differently than it used to "way back in the old days". The first thing to understand is that, with most modern solid state amplifier designs, the distortion doesn't rise gradually. The distortion starts out quite low, remains low throughout most of the amplifier's rated operating range, then rises sharply once you reach "full power". So, for example, with a typical amplifier, you may get 0.05% at 5 watts, 0.05% at 20 watts, 0.05% at 60 watts, 0.1% at 90 watts, and 1.0% at 100 watts. (Also keep in mind that the difference in loudness between 90 watts and 100 watts is an imperceptible fraction of a dB.) (And also keep in mind that, even a few percent distortion, if it only happens occasionally, on one or two loud peaks, isn't likely to be audible either.) (The way we think about that amongst ourselves is "the distortion is going to be inaudibly low until it starts to approach clipping".) The upshot of all this is that, rather than a careful decision about exactly how much distortion is audible, most amplifier ratings are not nearly that carefully thought out. In the example above.... - we could rate that amplifier as "90 watts at 0.1% THD" or as "100 watts at 1.0% THD" - we might go with the 0.1% number because we think it looks better "to be consistent with our other products" - or we might go with the 1% number "so we can get a nice round 100 watt rating" - or we might decide based on how our competitors advertise their competing models ("do they go for maximum power, or lowest THD, or do they target a specific number for one or the other?") The second thing worth understanding is how "dynamic power" and "dynamic headroom" work on modern amplifiers and specifically multi-channel amplifiers. (I'm going to avoid explaining the technical reasons why this makes sense for now....) Here's the deal... Most modern power amplifiers are designed to be able to deliver a lot of power CONTINUOUSLY. They are not specifically designed to be able to deliver more power for a short amount of time. So, if you look at it that way, they don't have much "dynamic headroom" and don't use that rating. Also note that, for a Class A/B amplifier, a given design must be optimized, in terms of efficiency, for a certain output power. (So, in order to make more power available short term, you end up reducing its efficiency at lower power levels.) The bottom line is that... We're not going to make a "100 watt amplifier with 100% dynamic headroom".... We'll just design it to be able to deliver 200 watts continuously and rate it accurately as "a 200 watt amplifier".... (We think it would be silly to design an amplifier that could deliver 200 watts, but only short term, then charge you for a 200 watt amplifier.) If you want to look at the equivalent of dynamic headroom on our amplifiers (short term power capability)... Just look at their "Two Channels driven" rating and ignore the "All Channels Driven" rating if it's a bit lower... (Since that's really the power they can deliver to two channels continuously or to any or all of their channels short term.) And, yes, you should always plan to buy the power you actually need. Here's the catch there.... Because music is dynamic, unless you're literally playing really long pipe organ notes, an amplifier will NEVER be asked to deliver anywhere near full power, from even one channel, for very long. Because normal music is dynamic, if you play it "as loud as you can without clipping the peaks", the average power you're using is usually between 1/10 and 1/20 of rated full power. So, in real life, most of the time, you've got, at most, one or two channels, delivering full rated power, for a small fraction of a second.
(And, if you really are playing sustained pipe organ notes, at full rated power, you should really be using a sub for that... because, among other things, that will warm up regular woofers pretty quickly.)
So, while we do include the "4 Ohms - all channels driven" rating on the MR1...
Unless you're "using it to light bulbs or heat up resistors" the "two channels driven" and even "five channels driven" numbers matter much more. Yes. Usual 'crest factor'.....the ratio of peak to average, is usually either considered to be 10 db or 20 db.....In general NOT a big deal except when you own lower than average sensitivity speakers and a combination of liking it LOUD and having larger space (cubic, not square feet or meters) So? With a 10db crest factor, you can be cruising along a 5 watts and instantly need 50.......for a short time period. That's at 10db.....20db gets a LOT worse, fairly quickly. from our truth in advertising department? 5 watts is LOUD...... My 4 ohm remark will stand. I'm always a little leery of any amp rated at 1% distortion. That's a red-flag for 'low headroom'....at least at higher distortion. The good news with THAT is nobody knows what most of those movie effects sound like, anyway..... |
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Post by marcl on Feb 8, 2023 14:05:06 GMT -5
I wanted to weigh in here on your last comment... about rating things at 1% THD. The simple fact is that, with almost all modern solid state designs, including ours, this works out a bit differently than it used to "way back in the old days". The first thing to understand is that, with most modern solid state amplifier designs, the distortion doesn't rise gradually. The distortion starts out quite low, remains low throughout most of the amplifier's rated operating range, then rises sharply once you reach "full power". So, for example, with a typical amplifier, you may get 0.05% at 5 watts, 0.05% at 20 watts, 0.05% at 60 watts, 0.1% at 90 watts, and 1.0% at 100 watts. (Also keep in mind that the difference in loudness between 90 watts and 100 watts is an imperceptible fraction of a dB.) (And also keep in mind that, even a few percent distortion, if it only happens occasionally, on one or two loud peaks, isn't likely to be audible either.) (The way we think about that amongst ourselves is "the distortion is going to be inaudibly low until it starts to approach clipping".) The upshot of all this is that, rather than a careful decision about exactly how much distortion is audible, most amplifier ratings are not nearly that carefully thought out. In the example above.... - we could rate that amplifier as "90 watts at 0.1% THD" or as "100 watts at 1.0% THD" - we might go with the 0.1% number because we think it looks better "to be consistent with our other products" - or we might go with the 1% number "so we can get a nice round 100 watt rating" - or we might decide based on how our competitors advertise their competing models ("do they go for maximum power, or lowest THD, or do they target a specific number for one or the other?") The second thing worth understanding is how "dynamic power" and "dynamic headroom" work on modern amplifiers and specifically multi-channel amplifiers. (I'm going to avoid explaining the technical reasons why this makes sense for now....) Here's the deal... Most modern power amplifiers are designed to be able to deliver a lot of power CONTINUOUSLY. They are not specifically designed to be able to deliver more power for a short amount of time. So, if you look at it that way, they don't have much "dynamic headroom" and don't use that rating. Also note that, for a Class A/B amplifier, a given design must be optimized, in terms of efficiency, for a certain output power. (So, in order to make more power available short term, you end up reducing its efficiency at lower power levels.) The bottom line is that... We're not going to make a "100 watt amplifier with 100% dynamic headroom".... We'll just design it to be able to deliver 200 watts continuously and rate it accurately as "a 200 watt amplifier".... (We think it would be silly to design an amplifier that could deliver 200 watts, but only short term, then charge you for a 200 watt amplifier.) If you want to look at the equivalent of dynamic headroom on our amplifiers (short term power capability)... Just look at their "Two Channels driven" rating and ignore the "All Channels Driven" rating if it's a bit lower... (Since that's really the power they can deliver to two channels continuously or to any or all of their channels short term.) And, yes, you should always plan to buy the power you actually need. Yes. Usual 'crest factor'.....the ratio of peak to average, is usually either considered to be 10 db or 20 db.....In general NOT a big deal except when you own lower than average sensitivity speakers and a combination of liking it LOUD and having larger space (cubic, not square feet or meters) So? With a 10db crest factor, you can be cruising along a 5 watts and instantly need 50.......for a short time period. That's at 10db.....20db gets a LOT worse, fairly quickly. from our truth in advertising department? 5 watts is LOUD...... My 4 ohm remark will stand. I'm always a little leery of any amp rated at 1% distortion. That's a red-flag for 'low headroom'....at least at higher distortion. The good news with THAT is nobody knows what most of those movie effects sound like, anyway..... Great explanation Keith! So here's a question ... how would one assess the suitability of this amp? For example, Magnepan recommends "high current" amps, defined as those that are spec'ed at double the power at 4ohms compared to 8ohms. Here's an amp that does that ... but the spec gives "short term" ratings at both 0.1 and 1.0% distortion ... and continuous "limited by thermal system". Okay so I know that if I immersed it in liquid nitrogen it couldn't produce infinite power forever  But in practical terms, how would one look at these specs and say it's suitable for driving a particular speaker?  |
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Post by leonski on Feb 8, 2023 15:17:46 GMT -5
I wanted to weigh in here on your last comment... about rating things at 1% THD. The simple fact is that, with almost all modern solid state designs, including ours, this works out a bit differently than it used to "way back in the old days". The first thing to understand is that, with most modern solid state amplifier designs, the distortion doesn't rise gradually. The distortion starts out quite low, remains low throughout most of the amplifier's rated operating range, then rises sharply once you reach "full power". So, for example, with a typical amplifier, you may get 0.05% at 5 watts, 0.05% at 20 watts, 0.05% at 60 watts, 0.1% at 90 watts, and 1.0% at 100 watts. (Also keep in mind that the difference in loudness between 90 watts and 100 watts is an imperceptible fraction of a dB.) (And also keep in mind that, even a few percent distortion, if it only happens occasionally, on one or two loud peaks, isn't likely to be audible either.) (The way we think about that amongst ourselves is "the distortion is going to be inaudibly low until it starts to approach clipping".) The upshot of all this is that, rather than a careful decision about exactly how much distortion is audible, most amplifier ratings are not nearly that carefully thought out. In the example above.... - we could rate that amplifier as "90 watts at 0.1% THD" or as "100 watts at 1.0% THD" - we might go with the 0.1% number because we think it looks better "to be consistent with our other products" - or we might go with the 1% number "so we can get a nice round 100 watt rating" - or we might decide based on how our competitors advertise their competing models ("do they go for maximum power, or lowest THD, or do they target a specific number for one or the other?") The second thing worth understanding is how "dynamic power" and "dynamic headroom" work on modern amplifiers and specifically multi-channel amplifiers. (I'm going to avoid explaining the technical reasons why this makes sense for now....) Here's the deal... Most modern power amplifiers are designed to be able to deliver a lot of power CONTINUOUSLY. They are not specifically designed to be able to deliver more power for a short amount of time. So, if you look at it that way, they don't have much "dynamic headroom" and don't use that rating. Also note that, for a Class A/B amplifier, a given design must be optimized, in terms of efficiency, for a certain output power. (So, in order to make more power available short term, you end up reducing its efficiency at lower power levels.) The bottom line is that... We're not going to make a "100 watt amplifier with 100% dynamic headroom".... We'll just design it to be able to deliver 200 watts continuously and rate it accurately as "a 200 watt amplifier".... (We think it would be silly to design an amplifier that could deliver 200 watts, but only short term, then charge you for a 200 watt amplifier.) If you want to look at the equivalent of dynamic headroom on our amplifiers (short term power capability)... Just look at their "Two Channels driven" rating and ignore the "All Channels Driven" rating if it's a bit lower... (Since that's really the power they can deliver to two channels continuously or to any or all of their channels short term.) And, yes, you should always plan to buy the power you actually need. Yes. Usual 'crest factor'.....the ratio of peak to average, is usually either considered to be 10 db or 20 db.....In general NOT a big deal except when you own lower than average sensitivity speakers and a combination of liking it LOUD and having larger space (cubic, not square feet or meters) So? With a 10db crest factor, you can be cruising along a 5 watts and instantly need 50.......for a short time period. That's at 10db.....20db gets a LOT worse, fairly quickly. from our truth in advertising department? 5 watts is LOUD...... My 4 ohm remark will stand. I'm always a little leery of any amp rated at 1% distortion. That's a red-flag for 'low headroom'....at least at higher distortion. The good news with THAT is nobody knows what most of those movie effects sound like, anyway..... Exactly why I chose 1%. That's the usual 'knee' in the curve and typically goes up...fairly quickly at that point So I'm always leery of an amp with a higher number for listed distortion since I know the amp is just about 'out of gas' at that point. If you run 10db crest factor material at say......10 watts (probably louder than I'd want!) and have a 1% limit of 80 watts? You are clearly exceeding th !% level on peaks..... I'd go so far as to say that an amps' 1% distortion level leaves NO useable headroom.... It turns into, IMO, some kind of rating game. I also note that the population of 4ohm HT speakers is fairly low. At least compared to 8ohm or perhaps even 6ohm.....Given that most HT speakers are of a higher impedance AND designed with few big dips? I'd not worry overmuch about 4 ohm power.....and distortion. |
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Post by KeithL on Feb 8, 2023 17:15:23 GMT -5
Thanks... I'd start by saying that I don't agree that Magneplanars really need "a high current amplifier". They generally have a pretty benign impedance... but they are a 4 Ohm speaker... and they do like plenty of power. So they may not work very well with something that just plain can't deliver much power into 4 Ohms... That amplifier you asked about is a Class D amp.... which can make life a bit more interesting. The fact that it's rated to run into 2 Ohms, and actually almost doubles from 4 Ohms to 2 Ohms, says that it can deliver plenty of current. Although, since Magneplanars are quite friendly 4 Ohm speakers, being able to run into a 2 Ohm load doesn't necessary offer it an advantage either. In practice many Class D amplifiers, while being very efficient, don't have much in the way of heat sinks... And this does tend to limit their maximum continuous output. This means that it probably can't deliver anywhere near that much power continuously (which is why they omit the continuous power rating). However most also tend to have excellent monitoring and protection circuitry. In other words, it would probably deliver lots of power when actually playing music, and deliver its rated power doing so... But, if you try to test it on a test bench, it will probably tend to overheat and shut down if you push it anywhere near that level... (So it will probably work great when playing music but not test so well...) Some Class D amps have issues running into unusual load impedances, or have a frequency response that varies when they do... But, again, since the Magneplanars are a pretty benign mostly resistive load, I wouldn't expect that to be an issue either. (And the fact that this amp is rated to run into 2 Ohms also tends to back up that supposition.) And, of course, some Class D amps "just plain don't sound very good" (although I see nothing whatsoever to suggest that would be the case here). The bottom line is that I would expect that amp to work just fine with Maggies... ------------------ I'm going to throw something in here that I'm sure Marcl already knows (just for the benefit of anyone else reading this): The amount of current a speaker "requires" depends ENTIRELY on the load impedance it presents. In technical terms we say that "a normal high-fidelity amplifier is a voltage source". The amplifier delivers a specific signal VOLTAGE to the load (the speaker). And, for that given amount of output voltage from the amplifier, the load " DRAWS the current it needs". If the amplifier is unable to supply that amount of current then the result will be distortion... And, if there is no distortion, then you know that the amplifier is capable of delivering the necessary amount of current... There is no real benefit to having an amplifier that can deliver more current than the load draws. (The only conceivable justification is that the amplifier might distort more "if stressed near its limits".) The main legitimate reason for a speaker to "require a high current amplifier" is that it has an unusually low impedance and so "will draw a lot of current". (This is not the case with Magneplanars.) There is also the possibility that, if the speaker has an exceptionally massive woofer, and a powerful "motor", it may require a lot of current "to properly damp the driver". (The amplifier is "providing the current to cancel out the current due to the back-EMF from the driver"... which again shows up as "the current drawn by the load".) It is possible to have an amplifier that works well into a resistive load but doesn't work well with some speakers for this reason. (However, since this also doesn't apply at all to Magneplanars, this is a non-issue too.) I strongly suspect that "what Magnepan really means" is that "Magneplanars really need a powerful amplifier to run well".... And wimpy little amplifiers and AVRs, especially of the sort with a very low power output into 4 Ohms, should therefore be avoided. (And, yes, I know that some folks find their performance perfectly acceptable with low powered amps, especially tube amps... but they do TEND to like lots of power, especially if you want them to get at all loud..) ------------------------------- Great explanation Keith! So here's a question ... how would one assess the suitability of this amp? For example, Magnepan recommends "high current" amps, defined as those that are spec'ed at double the power at 4ohms compared to 8ohms. Here's an amp that does that ... but the spec gives "short term" ratings at both 0.1 and 1.0% distortion ... and continuous "limited by thermal system". Okay so I know that if I immersed it in liquid nitrogen it couldn't produce infinite power forever But in practical terms, how would one look at these specs and say it's suitable for driving a particular speaker? View Attachment |
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Post by KeithL on Feb 8, 2023 17:58:23 GMT -5
I quite agree... at some point it all devolves into a somewhat pointless "rating game". However my point is simply that, with most amplifiers, "the power rating is going to be at or just below the point where the curve starts to climb sharply"... And the actual power rating you'll see for the 0.1% point and the 1% point is only going to be different by a very small fraction of a dB. (So you're talking about a fraction of a dB difference in headroom.) To be fair, if you've got a 100 watt amp, the occasional clipped single drumbeat, or pistol shot, is probably not going to be especially audible anyway. (It's a single, very short, transient waveform... and it's almost certainly already been crushed by a peak limiter during production anyway.) And you're going to need a lot more power if you want to be sure that really loud peaks don't ever clip. (Either way, whether the amp "runs out" at 80 watts or 90 watts is unlikely to make much difference.) --------------------------- Exactly why I chose 1%. That's the usual 'knee' in the curve and typically goes up...fairly quickly at that point So I'm always leery of an amp with a higher number for listed distortion since I know the amp is just about 'out of gas' at that point. If you run 10db crest factor material at say......10 watts (probably louder than I'd want!) and have a 1% limit of 80 watts? You are clearly exceeding th !% level on peaks..... I'd go so far as to say that an amps' 1% distortion level leaves NO useable headroom.... It turns into, IMO, some kind of rating game. I also note that the population of 4ohm HT speakers is fairly low. At least compared to 8ohm or perhaps even 6ohm.....Given that most HT speakers are of a higher impedance AND designed with few big dips? I'd not worry overmuch about 4 ohm power.....and distortion. |
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Post by vcautokid on Feb 8, 2023 18:59:36 GMT -5
And here we go again. Denon is introducing a new flagship receiver for $6500.00! Yeah okay great, they are doing some good things, but how does that stack with the fact I can get 3 MR-1s for that and pocket some change. Emotiva is holding the for what counts, and doing it right. Denon wants to do the right thing too, but $6500.00 is what it will cost you. Talk about a false economy there. Score another for the MR-1.
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Post by leonski on Feb 9, 2023 0:21:31 GMT -5
I quite agree... at some point it all devolves into a somewhat pointless "rating game". However my point is simply that, with most amplifiers, "the power rating is going to be at or just below the point where the curve starts to climb sharply"... And the actual power rating you'll see for the 0.1% point and the 1% point is only going to be different by a very small fraction of a dB. (So you're talking about a fraction of a dB difference in headroom.) To be fair, if you've got a 100 watt amp, the occasional clipped single drumbeat, or pistol shot, is probably not going to be especially audible anyway. (It's a single, very short, transient waveform... and it's almost certainly already been crushed by a peak limiter during production anyway.) And you're going to need a lot more power if you want to be sure that really loud peaks don't ever clip. (Either way, whether the amp "runs out" at 80 watts or 90 watts is unlikely to make much difference.) Exactly why I chose 1%. That's the usual 'knee' in the curve and typically goes up...fairly quickly at that point So I'm always leery of an amp with a higher number for listed distortion since I know the amp is just about 'out of gas' at that point. If you run 10db crest factor material at say......10 watts (probably louder than I'd want!) and have a 1% limit of 80 watts? You are clearly exceeding th !% level on peaks..... I'd go so far as to say that an amps' 1% distortion level leaves NO useable headroom.... It turns into, IMO, some kind of rating game. I also note that the population of 4ohm HT speakers is fairly low. At least compared to 8ohm or perhaps even 6ohm.....Given that most HT speakers are of a higher impedance AND designed with few big dips? I'd not worry overmuch about 4 ohm power.....and distortion. MOST indeed, Keith. In years past NAD had amps with IIRC......6 db headroom. I would guess, a fairly HIGH voltage PS but a transformer on the small side for output..... So you could get a decent continuous power, but have plenty of capacity at a higher voltage for 'peaks'...... At least that's all I can figure. Even my very modest Parasounds call out 1.3db headroom....Whcih I suspect is 'typical' ....Thought they make what I consider Wacky claims for current....which must certainly be at a very low voltage and for the briefest of times.... |
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ttocs
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I always have a wonderful time, wherever I am, whomever I'm with. (Elwood P Dowd)
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Post by ttocs on Feb 9, 2023 0:39:35 GMT -5
To be fair, if you've got a 100 watt amp, the occasional clipped single drumbeat, or pistol shot, is probably not going to be especially audible anyway. (It's a single, very short, transient waveform... and it's almost certainly already been crushed by a peak limiter during production anyway.) The cymbal "crash" is a sort of "sustained peak" sound I use for amplifier listening tests and my speakers, such as can be found on Billy Cobham's Spectrum album. When they sound smooth, life is good. When they sound harsh or painful, I need go no further with the amp in question. |
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Post by akcorr on Feb 9, 2023 8:22:23 GMT -5
Mine arrived late last night. Did the speaker and XPA-5 connections but didn't have a chance to run EMO-Q. Question for you all because I honestly don't know: Can a 7.2.2 configuration have either Front or Rear Height channels or is a 7.2.2 configuration only referring to 7 bed channels, 2 subwoofers, and 2 Front height channels only? Can those height channels be rear height channels?
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) 
But in practical terms, how would one look at these specs and say it's suitable for driving a particular speaker?
