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Post by pknaz on Mar 4, 2017 12:18:20 GMT -5
Simple math. What is the efficiency of those new speakers you have? Increase that number by +3 for each doubling of power until you reach your max comfortable listening level, then +3 or +6 for safety. That's how much power you need. Example:
Efficiency = 89db/1watt/1meter
2 Watts = 92db listening level
4 Watts = 95db listening level (this is very loud, and will cause permanent hearing dmg at prolonged periods)
8 Watts = 98db listening level
16 Watts = 101db listening level
32 Watts = 104db listening level
64 Watts = 107db listening level
128 Watts = 110db listening level
256 Watts = 113db Listening level
....
More than likely, the power rating on these speakers is a thermal rating, so depending on the bass alignment, they might not actually handle 300Watts on certain bass frequencies.
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Post by leonski on Mar 4, 2017 14:30:48 GMT -5
Music and movies are both very dynamic, of course.
You might cruise along at 2 watts and it is pretty loud. But something happens and you are suddenly at 10x the power for an instant. And 10db louder.
You could feed your speaker a continuous 32 watts, using a sine wave or other test material, but WHY? And how long would the speaker take it?
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Post by pknaz on Mar 4, 2017 19:39:13 GMT -5
Those are RMS numbers, handling dynamics is why you have peak power. with the example I gave, listening at an average level of 98db, which is insanely loud, by the way, you would still only need roughly 80watts to hit your 10db peak.
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Post by pknaz on Mar 4, 2017 19:52:13 GMT -5
I believe the OP speakers in question are 90db/w/m, which means 250watts RMS would provide safe power requirements for any safe listening level. The difference between 250watts and 300 (the speakers max rating) would be less than one db. Even going up to 500Watts (beyond the safe range of the speaker) would only give you an additional 3db of headroom, and likewise, the next jump for another 3db is 1,000 watts. Understanding real world listening levels, how much dynamic range is really used in mastering a playback recording, and realistic power requirements helps to determine real world requirements on power. Don't get me wrong, I use a set of XPA-1's, but even at ear damage level listening SPLs, I'm still not even peaking at 250 Watts, and I have similarly efficient speakers.  When employing a fletcher munson curve, and slowly increasing gain to see where my system limits were, I ran into driver induced distortion long before reaching the amps limits. |
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Post by leonski on Mar 4, 2017 21:12:32 GMT -5
It only is a 'danger' to the speaker if you REALLY crank it. And yes, I'm certain the drivers, probably tweeter first, will distort AUDIBLY before the amp reaches its limits.
Why is this even a discussion? 90db sensitive (not efficient) speakers with 250 watts? Even cruising along at 25 watts with a 10db crest factor (=250 watts) will produce Ear Shattering
levels in any normal room. I except a room of greather than 10,000 cubic feet with 5 walls (include ceiling) of wide-band absorption. and Soft Carpets and furnishings for the '6th wall'. (floor)
And please don't forget that the scale in the above post is for a SINGLE speaker at 1 meter. Sound drops off as a direct function of distance but you have 2 speakers and Room Gain to contend with.
It isn't as simple as the numbers would have you 'believe'.
Fletcher and Munson are banned from my house. Even if they bring the beer.
I've always told people that instead of simply buying MORE power, which I'll admit is cheap these days, to, For The Same money, find a speaker they like as much with higher sensitivity and put the differnce
into a Better Amp.
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Post by pknaz on Mar 5, 2017 12:36:26 GMT -5
Leonski, I think we're relatively in agreement here.
Spending money on speakers and room treatments are almost always offer better results than amplifiers, up to a certain point, of course.
There will be 'some' gain when driving additional speakers (Not the +3 the math may tell you). Even with wide band absorbtion in the room, you'd have to have 100% of the surface area covered and know the absorption rates of the coverings to calculate the decrease in SPL. I believe it was Floyd Toole who found that in small rooms SPL does not decrease by -6db per doubling of the distance as it would in open air due to reflections.
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Post by garbulky on Mar 5, 2017 15:14:36 GMT -5
The difference between amps so far have been a lack of top to bottom composure between volumes. The XPA-1 does pretty good with it. So does the XPA-2. The smaller amps will still have more than enough power for most speakers but they can't maintain the mid range full ness or the bass extension without coming off as a little loose, smeared or lacking in detail.
Mind you not all amps do this. But that is the general impression I've been getting. I've heard very powerful amps do the same thing where they lack composure too. A lot of the solid state units I've heard, the main differences I can see are due to larger power supplies.
Mind you some of the tube amps I've heard do not express this lack of composure in the mid range. Though the bass can get wooly. I've heard a 12 watt amp and a 60 watt tube amp sound great and superior to say an XPA-5. Their sound quality can easily rival an XPA-2 - though they sound different. So it's hard to say what is the contributor.
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Post by leonski on Mar 5, 2017 16:20:20 GMT -5
pknaz,
What you note about the lack of 6db decrease due to 2x distance is one way to state 'Room Gain'.
I wouldn't bother to Calculate this even if I had a good model to start with. Nope. MEASURE a before
and after situation will give you a much better idea.
Room setup IS key and frequently omitted since other factors come into play, like it MUST go there or in
the garage, sort of stuff.
garbulky: What you may note is or MIGHT be due to an amps ability or INability to drive REAL speaker loads
which usually appear to a greater or lesser degree as a capacitor or inductor to the partnering amp. Even
amps which measure pretty much the SAME into a resistor will fail in this regard. And some 'big names' may
even fail. A speaker with a big impedance dip at the same place as a huge reactance swing is worst case scenario.
HT speakers are by design, somewhat of an easier load. I don't care what anybody SAYS about 'my speaker is a tough load',
it probably isn't if being successfully driven by an HT receiver or similar. Few people know what the reactance of their
particular speaker measures and 3 ohms impedance is not really 'difficult' unless it extends for sevaral octaves and is
coupled with huge reactance swings.
The true way to measure an amp is with a simulated speaker dummy load with real peaks and dips in impedance as well
as reactive elements. If it were a standard, amps could more easily be compared.
Tube amps with output transformers can track the impedance swings of the paired speaker. This will give peaks and dips in
the response Tube amps also do not like either capacitive or inductive loads, I don't 'member which.
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Post by saru on Mar 10, 2017 11:53:54 GMT -5
So today I'd managed to find my 14AWG extension cords so that I could get the XPA-1Ls off the power conditioner and into a wall outlet that was too far to stretch with the existing power cords. As I was unplugging the amps from the Panamax, I noticed something odd: the gauges for the power cables were different between each amp! The one connected to my left channel was 14AWG but the one on the right channel was 18AWG. I'm not sure if they came to me that way (I bought them used from a Lounger) or if I just goofed up and swapped one cord to another component during a re-arrangement at some point. In any case, I wonder if this is why my left channel has been seeming more present than the right since I brought the amps up to my office.
And speaking of power cables: anyone have good experience with upgrading stock cords for their amps? I've been looking at the Pangea cables for the past week, but it seems a little silly to drop $150-200 for an AC9 cable to power an amp that retailed for $500.
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Post by monkumonku on Mar 10, 2017 12:00:41 GMT -5
So today I'd managed to find my 14AWG extension cords so that I could get the XPA-1Ls off the power conditioner and into a wall outlet that was too far to stretch with the existing power cords. As I was unplugging the amps from the Panamax, I noticed something odd: the gauges for the power cables were different between each amp! The one connected to my left channel was 14AWG but the one on the right channel was 18AWG. I'm not sure if they came to me that way (I bought them used from a Lounger) or if I just goofed up and swapped one cord to another component during a re-arrangement at some point. In any case, I wonder if this is why my left channel has been seeming more present than the right since I brought the amps up to my office. And speaking of power cables: anyone have good experience with upgrading stock cords for their amps? I've been looking at the Pangea cables for the past week, but it seems a little silly to drop $150-200 for an AC9 cable to power an amp that retailed for $500. If you think your left channel seems more "present" than the right, then switch the power cords between the left and right and see if the right channel now seems more "present." Or better yet, ask someone to do the switching and let them decide if they really switch it or just leave it as is, then see if you can tell which channel seems to be more present. I use Monoprice 14AWG for my stuff. Spending any more than that is silly. The cords supplied by the manufacturer are perfectly adequate. I just use Monoprice because they offer different lengths and also I like a uniform AWG in the system. |
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Post by saru on Mar 10, 2017 12:20:38 GMT -5
So today I'd managed to find my 14AWG extension cords so that I could get the XPA-1Ls off the power conditioner and into a wall outlet that was too far to stretch with the existing power cords. As I was unplugging the amps from the Panamax, I noticed something odd: the gauges for the power cables were different between each amp! The one connected to my left channel was 14AWG but the one on the right channel was 18AWG. I'm not sure if they came to me that way (I bought them used from a Lounger) or if I just goofed up and swapped one cord to another component during a re-arrangement at some point. In any case, I wonder if this is why my left channel has been seeming more present than the right since I brought the amps up to my office. And speaking of power cables: anyone have good experience with upgrading stock cords for their amps? I've been looking at the Pangea cables for the past week, but it seems a little silly to drop $150-200 for an AC9 cable to power an amp that retailed for $500. If you think your left channel seems more "present" than the right, then switch the power cords between the left and right and see if the right channel now seems more "present." Or better yet, ask someone to do the switching and let them decide if they really switch it or just leave it as is, then see if you can tell which channel seems to be more present. I use Monoprice 14AWG for my stuff. Spending any more than that is silly. The cords supplied by the manufacturer are perfectly adequate. I just use Monoprice because they offer different lengths and also I like a uniform AWG in the system. Oh, that's a good idea. Cords have been swapped; I'll leave 'em that way for a while and see if anything sounds different. I probably will do some kind of power cord upgrade on these. Mainly for length (I'm not too keen on having these long extension cords in the system), but also for the AWG uniformity, as you mentioned. |
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Post by leonski on Mar 10, 2017 16:05:26 GMT -5
So today I'd managed to find my 14AWG extension cords so that I could get the XPA-1Ls off the power conditioner and into a wall outlet that was too far to stretch with the existing power cords. As I was unplugging the amps from the Panamax, I noticed something odd: the gauges for the power cables were different between each amp! The one connected to my left channel was 14AWG but the one on the right channel was 18AWG. I'm not sure if they came to me that way (I bought them used from a Lounger) or if I just goofed up and swapped one cord to another component during a re-arrangement at some point. In any case, I wonder if this is why my left channel has been seeming more present than the right since I brought the amps up to my office. And speaking of power cables: anyone have good experience with upgrading stock cords for their amps? I've been looking at the Pangea cables for the past week, but it seems a little silly to drop $150-200 for an AC9 cable to power an amp that retailed for $500. Than Don'T buy the AC9! The 14 is MORE than sufficient for your amp. Unless you run Sine-Waves at clipping for hours on end. I'm sending off for a pair for my Parasound A23s which are 125x2 each. Do NOT sell the DIY option short. |
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Post by saru on Mar 10, 2017 16:39:12 GMT -5
So today I'd managed to find my 14AWG extension cords so that I could get the XPA-1Ls off the power conditioner and into a wall outlet that was too far to stretch with the existing power cords. As I was unplugging the amps from the Panamax, I noticed something odd: the gauges for the power cables were different between each amp! The one connected to my left channel was 14AWG but the one on the right channel was 18AWG. I'm not sure if they came to me that way (I bought them used from a Lounger) or if I just goofed up and swapped one cord to another component during a re-arrangement at some point. In any case, I wonder if this is why my left channel has been seeming more present than the right since I brought the amps up to my office. And speaking of power cables: anyone have good experience with upgrading stock cords for their amps? I've been looking at the Pangea cables for the past week, but it seems a little silly to drop $150-200 for an AC9 cable to power an amp that retailed for $500. Than Don'T buy the AC9! The 14 is MORE than sufficient for your amp. Unless you run Sine-Waves at clipping for hours on end. I'm sending off for a pair for my Parasound A23s which are 125x2 each. Do NOT sell the DIY option short. Actually, I ended up putting a pair of AC14's in my Amazon cart this afternoon. I am mainly interested in trying them on various components (Oppo, Gumby, XSP-1, XMC-1, etc.), but of course I'll stick them in the amps too and see what happens. At $40 each for 1.5m lengths, it's not a big loss if I don't notice significant SQ gains. Only reason I considered the thicker AC9's was user comments complaining that the AC14 didn't deliver on amp performance for them, but I'll see firsthand whether that's true or not. |
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Post by leonski on Mar 10, 2017 17:54:13 GMT -5
If you want 12ga which would be nice for higher powered amps, then DIY is still on the table for maybe what the 14 ga Pangea cords run. Here is link to BELDEN 83803 which is a very highly regarded and Fully Shielded 12x3 power cable. Several DIYs exist touting this as one of the best wires for the Home Experimenter. www.parts-express.com/belden-83803-12-awg-3-conductor-power-cable-1-ft-usa--100-790Much more $$ than I remember, I'd shop PRICE or maybe try to get people together for a Group Buy. Count me in for 15 to 20 feet. Connectors? Also an expense, and some are WACKY amounts of $$$. Except for a very FEW and very HIGH powered amps, this should be fine for runs to 6 or 8 feet from outlet: Let me know about a group buy and we'll figure out how to organize it. |
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