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post #811 of 837 Old 06-24-2014, 10:23 PM
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Quote:
Originally Posted by TownsendAvalnch View Post

Playing with the SPL calculator you linked, it seems to be very hard to get 105dB as the peak. For LS50 paired with a 100 Watt amp, this gives an SPL of 100.5 dB at 11 feet.
Yes, the LS50 is meant to be for near field placement. Playing around with Peak SPL Calculator, using the LS50 efficiency, a pair of speakers and having them in a corner placement (18"to 24"from wall), the distance works out be about 9.2 ft. to get around 105dB peak. That means you would need to move the couch up from the back wall by about 4'10" to get the desired SPL. The good side of this having space behind the couch so you can out up some broad band sound absorbing material to help reduce the reflections from the speakers - all speakers would have this issue in a room.

Quote:
Originally Posted by TownsendAvalnch View Post
(Side note: in trying to understand the physics of this and how to pair an amp with a speaker, I am finding that some manufacturers don't list the speaker's power rating . This doesn't make any sense to me. I looked up the Wilson Alexandria XLF for the heck of it. and it only listed the minimum power requirements for the amp, but it didn't list the power rating for the speaker or what the max was. Seems the max power amp the KEF LS50 can handle is 100 Watts based on the spec sheet. How does one know if the setup can prevent "clipping" and therefore a higher power amp can be used?)
Most good speaker manufacturers will state a range of power requirement for continuous operation. For the LS50, KEF states the range to be 25W to 100W of continuous power rating. The amp must be able to produce the minimum power cleanly, i.e. no clipping and with minimal distortion. A good amp manufacturer will state what it can produce in 2-channel mode at nominal resistance of 8 ohms. Best to look for amps that can also drive nominal resistance of 4 ohms as the LS50 can go done to about 3 ohms. Overall you want the amp to have less THD (less than 1%) at it's maximum rated output.

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post #812 of 837 Old 06-26-2014, 07:42 AM
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Thank you for the replies and the links to those blog entries. The problem I am running into is that there are so many subtly different numbers, but those differences are extremely important. Example: blog entry 3 lists power out, minimum power out, and maximum power out as three important numbers to know. Max is peak-to-peak. Minimum is continuous rating. Which is all fine.

However, looking at actual amplifier or receiver specs, they generally only list one number (like "power output") and do not specify how that measurement is taken or what the range is. Then I have the problem of matching "speaker power rating" to amplifier specs, when the numbers for BOTH components could be measured in slightly different (but important) ways. Example: KEF LS50 "amplifier requirements" are 25 to 100 Watts. Are those continuous or peak to peak numbers? Is that the power rating of the speakers as well, or just the amplifier (or are these the same)? I'll fry the speakers if I pick an amp that has a continuous rating ~100 Watts (I think). But I don't want to go too low either. Then I also need to multiply the numbers by a factor to find the right power "range". Etc. It's incredibly confusing. Mainly because there are different ways to measure power and there is no consistency between reported specs.

Other problem is that I live in an apartment that has thick concrete between the units, but I'm not sure how thick or how well it absorbs sound. Maybe a sound system that reaches 105 dB will be completely unnecessary as I won't ever play it that loud? Because of this I am mostly interested in sound clarity, so I'm guessing a mini-monitor like the LS50 makes sense even if the SPL at my listening position doesn't reach 105 dB, but I'm not 100% sure on that.
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post #813 of 837 Old 06-26-2014, 08:26 AM
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My room is similar to yours. 13x27 with 14 foot vaulted ceilings.
With 2 subs in the room to even out the bass.
I sit 9 feet from the Ls50's.

In 2 channel mode with subs on volume is never an issue.
My Sherwood Newcastle 972 at -10 is extremely loud.
During the 15 months with my Ls50's I have considered a larger
amplifier but have yet to see the need.

In 7 channel mode the the room is perfect with movies.
The Trinnov is mostly responsible for correcting this odd room but
the Ls50's really are exceptional.

Steve
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post #814 of 837 Old 06-26-2014, 10:37 AM
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Quote:
Originally Posted by TownsendAvalnch View Post
Thank you for the replies and the links to those blog entries. The problem I am running into is that there are so many subtly different numbers, but those differences are extremely important. Example: blog entry 3 lists power out, minimum power out, and maximum power out as three important numbers to know. Max is peak-to-peak. Minimum is continuous rating. Which is all fine.

However, looking at actual amplifier or receiver specs, they generally only list one number (like "power output") and do not specify how that measurement is taken or what the range is. Then I have the problem of matching "speaker power rating" to amplifier specs, when the numbers for BOTH components could be measured in slightly different (but important) ways. Example: KEF LS50 "amplifier requirements" are 25 to 100 Watts. Are those continuous or peak to peak numbers? Is that the power rating of the speakers as well, or just the amplifier (or are these the same)? I'll fry the speakers if I pick an amp that has a continuous rating ~100 Watts (I think). But I don't want to go too low either. Then I also need to multiply the numbers by a factor to find the right power "range". Etc. It's incredibly confusing. Mainly because there are different ways to measure power and there is no consistency between reported specs.

Other problem is that I live in an apartment that has thick concrete between the units, but I'm not sure how thick or how well it absorbs sound. Maybe a sound system that reaches 105 dB will be completely unnecessary as I won't ever play it that loud? Because of this I am mostly interested in sound clarity, so I'm guessing a mini-monitor like the LS50 makes sense even if the SPL at my listening position doesn't reach 105 dB, but I'm not 100% sure on that.
Hi,
The KEF LS50 is rated for 25w - 100w of continuous power. If you are unsure of the specified rating of an amplifier, it would be best to contact the amp manufacturer.

Sincerely,

KEF America
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post #815 of 837 Old 06-26-2014, 12:08 PM - Thread Starter
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Quote:
Originally Posted by KEFAmerica View Post
Hi,The KEF LS50 is rated for 25w - 100w of continuous power. If you are unsure of the specified rating of an amplifier, it would be best to contact the amp manufacturer.

Sincerely, KEF America
So I would assume that this amp should be good enought, yes?

- Parasound A23 http://www.parasound.com/halo/a23.php
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post #816 of 837 Old 06-26-2014, 01:06 PM
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Originally Posted by wse View Post
So I would assume that this amp should be good enought, yes?

- Parasound A23 http://www.parasound.com/halo/a23.php
Hi,
The Parasound A23 is rated at 125 watts RMS x 2, 20 Hz - 20 kHz, 8 Ω, both channels driven,so it will have no problem powering the KEF LS50. Whether you like the combination of a Parasound Amp with the KEF LS50 is your subjectivity.

Sincerely,

KEF America
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post #817 of 837 Old 06-26-2014, 06:26 PM - Thread Starter
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Quote:
Originally Posted by KEFAmerica View Post
Hi,
The Parasound A23 is rated at 125 watts RMS x 2, 20 Hz - 20 kHz, 8 Ω, both channels driven,so it will have no problem powering the KEF LS50. Whether you like the combination of a Parasound Amp with the KEF LS50 is your subjectivity. Sincerely, KEF America
Any recommendations?
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post #818 of 837 Old 06-26-2014, 08:01 PM
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I would think Parasound Halo would match up quite well.
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post #819 of 837 Old 06-26-2014, 10:57 PM
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Quote:
Originally Posted by TownsendAvalnch View Post
Example: blog entry 3 lists power out, minimum power out, and maximum power out as three important numbers to know. Max is peak-to-peak. Minimum is continuous rating. Which is all fine.
Using the worked example on KEF blog, here is the continuous power range for LS50 per speaker basis.

Minimum continuous power = Min rating of speaker x 2 x 0.8 = 25 x 2 x 0.8 = 40W
Maximum continuous power = Max rating of speaker x 2 x 0.8 = 100 x 2 x 0.8 = 160W

So you would look for an amp that has a continuous rating per channel in the above range. The Parasound Halo A23 2-channel amp fits into this range (125W per channel at the LS50 nominal impedance of 8 ohms). Some members have reported a good match between the LS50 and Parasound amps.

Quote:
Originally Posted by TownsendAvalnch View Post
However, looking at actual amplifier or receiver specs, they generally only list one number (like "power output") and do not specify how that measurement is taken or what the range is. Then I have the problem of matching "speaker power rating" to amplifier specs, when the numbers for BOTH components could be measured in slightly different (but important) ways. Example: KEF LS50 "amplifier requirements" are 25 to 100 Watts. Are those continuous or peak to peak numbers? Is that the power rating of the speakers as well, or just the amplifier (or are these the same)? I'll fry the speakers if I pick an amp that has a continuous rating ~100 Watts (I think). But I don't want to go too low either. Then I also need to multiply the numbers by a factor to find the right power "range". Etc. It's incredibly confusing. Mainly because there are different ways to measure power and there is no consistency between reported specs.
Rating by KEF is for continuous power. See worked example above on the amp power range. The amps are nominally rated for maximum continuous power. Look for amps that have low THD (<1%) at the speaker nominal impedance rating of 8 ohms. Better yet, check with the amp supplier if 4 ohms is supported as the LS50 goes down to 3 ohms. Using the Parasound Halo A23 as an example, it has a THD of <0.06% at full power. This is very good. It also supports both 8 ohm and 4 ohm loads, so no problem with the LS50.

Quote:
Originally Posted by TownsendAvalnch View Post
Other problem is that I live in an apartment that has thick concrete between the units, but I'm not sure how thick or how well it absorbs sound. Maybe a sound system that reaches 105 dB will be completely unnecessary as I won't ever play it that loud? Because of this I am mostly interested in sound clarity, so I'm guessing a mini-monitor like the LS50 makes sense even if the SPL at my listening position doesn't reach 105 dB, but I'm not 100% sure on that.
105 dB is extremely loud at the Main Listening Position, but it's a transient condition (think of an explosion scene in a movie). The reference level is nominally set at 85dB (movie theater reference) and most people find this to be too loud. People would generally turn it down by some amount. By how much is a preference thing.

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post #820 of 837 Old 06-27-2014, 06:39 AM
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I've seen KEF demoing the LS50s with Parasound Halo gear and Arcam FMJ gear. I didn't care for the A23 paired with them and a Benchmark DAC2 HGC but you might.

I'm swapping out my 30" Sanus NF30 stands for a set of NHT P6 pedestals, they match the LS50s pretty well (not my setup as I don't have the pedestals yet):




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post #821 of 837 Old 06-27-2014, 07:49 AM
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Originally Posted by wse View Post
Any recommendations?
Hi,
KEF doesn't recommend any specific accompanying equipment (amps, stands, cables, DACs...etc.) since everyone's needs and preference are different.

Sincerely,

KEF America
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post #822 of 837 Old 06-27-2014, 12:17 PM
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Quote:
Originally Posted by KEFAmerica View Post
Hi,
The Parasound A23 is rated at 125 watts RMS x 2, 20 Hz - 20 kHz, 8 Ω, both channels driven,so it will have no problem powering the KEF LS50. Whether you like the combination of a Parasound Amp with the KEF LS50 is your subjectivity.

Sincerely,

KEF America
This amp is perfect for the LS50s in my nearfield setup. It has all the transparency you could ever ask for. I did add a tube pre-amp to take the slight edge off my system due to my DAC. The system sounds sublime with this setup.
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post #823 of 837 Old 06-27-2014, 01:27 PM
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Early this year I visited a local dealer, listened to an Anthem Integrated 225 and was awestruck by the detail and clarity coming from the speakers. It was driving a Triton 7 so I knew this amp will easily drive the LS50s as well...for an even better output.
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post #824 of 837 Old 06-27-2014, 05:42 PM
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Quote:
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This amp is perfect for the LS50s in my nearfield setup. It has all the transparency you could ever ask for. I did add a tube pre-amp to take the slight edge off my system due to my DAC. The system sounds sublime with this setup.
I think the DAC was the issue with the sound I was getting with my A23 as well.
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post #825 of 837 Old 07-02-2014, 06:53 AM
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I have a question for KEFAmerica. If one is using the port plugs, obviously it reduces the bass output of the speakers. But my question is, does it also increase the performance ability or efficiency of the driver in anyway, such as the same if one were to place a high pass filter in the circuit upstream?

Last edited by jkhome; 07-02-2014 at 07:04 AM.
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post #826 of 837 Old 07-02-2014, 07:20 AM
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Originally Posted by jkhome View Post
I have a question for KEFAmerica. If one is using the port plugs, obviously it reduces the bass output of the speakers. But my question is, does it also increase the performance ability or efficiency of the driver in anyway, such as the same if one were to place a high pass filter in the circuit upstream?
Hi JKhome,
The answer is no. The port plug simply changes how the speaker reacts within the room it is placed and has nothing to do with speaker efficiency or electrical performance.

Sincerely,

KEF America
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post #827 of 837 Old 07-02-2014, 09:30 AM
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Originally Posted by KEFAmerica View Post
Hi JKhome,
The answer is no. The port plug simply changes how the speaker reacts within the room it is placed and has nothing to do with speaker efficiency or electrical performance.

Sincerely,

KEF America
OK, thanks. Nice to have the port plug option anyway.
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post #828 of 837 Old 07-02-2014, 01:38 PM
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KEFAmerica - with Pioneer ahead of the ballgame, is there anything KEF is planning on the horizon for Dolby Atmos?
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post #829 of 837 Old 07-02-2014, 01:49 PM - Thread Starter
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How does the plug affect the sound of the LS-50?
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post #830 of 837 Old 07-02-2014, 02:18 PM
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If the port is plugged can they be put right against a wall for surround duty?
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post #831 of 837 Old 07-02-2014, 05:27 PM
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Quote:
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How does the plug affect the sound of the LS-50?
It reduces the bass output of the speaker. If the speaker is set close to a surface such as a wall or in a cabinet, the speaker can get more bass boom. The plugs help reduce this. If you have the owners manual, it shows the distances recommended for partial or full port plugging.

In my case, the rear ports of the speakers are 20" from the sidewall. But also I wanted to reduce the bass output so that the mid bass subs I use located right next to the KEFs can be ran higher. Works great.
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post #832 of 837 Old 07-02-2014, 05:28 PM - Thread Starter
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Quote:
Originally Posted by KEFAmerica View Post
Hi,
KEF doesn't recommend any specific accompanying equipment (amps, stands, cables, DACs...etc.) since everyone's needs and preference are different.

Sincerely,

KEF America

How would the Pioneer Class D3 Amplification sound with the KEF LS50? Has any one tried and what did you think?


http://www.pioneerelectronics.com/ep...0Sheet_v13.pdf

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post #833 of 837 Old 07-02-2014, 05:29 PM - Thread Starter
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Quote:
Originally Posted by jkhome View Post
It reduces the bass output of the speaker. If the speaker is set close to a surface such as a wall or in a cabinet, the speaker can get more bass boom. The plugs help reduce this. If you have the owners manual, it shows the distances recommended for partial or full port plugging.

In my case, the rear ports of the speakers are 20" from the sidewall. Also I want to reduce the bass output so that the mid bass subs next to them can be ran higher. Works great.
They don't take in consideration the fact that you can use crossover? Why not just setting the crossover at 80HZ and no plugs problem solved


So they say:

< 7.87 inches from the back wall both plugs

< 19.685 inches from the back wall one plug

> 19.685 inches from the back wall no plugs

http://www.kef.com/uploads/files/en/...iew_250412.pdf

In addition I tried stands at 24" and 30" I like it better at 30"

Last edited by wse; 07-02-2014 at 05:36 PM.
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post #834 of 837 Old 07-02-2014, 06:04 PM
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Quote:
Originally Posted by wse View Post
They don't take in consideration the fact that you can use crossover? Why not just setting the crossover at 80HZ and no plugs problem solved


So they say:

< 7.87 inches from the back wall both plugs

< 19.685 inches from the back wall one plug

> 19.685 inches from the back wall no plugs

http://www.kef.com/uploads/files/en/...iew_250412.pdf

In addition I tried stands at 24" and 30" I like it better at 30"
Yes that's one way to do it, but in two channels systems, and in other apps, alot of folks don't run their mains through a crossover. I run my KEFs full range (via a two channel diy tube preamp), and then cross over the subs downstream.

I actually went the other way with the speaker height. Started out with the speakers on Isoacoustic platforms, sitting on 24" stands (which equaled around a 30" height). But settled with the speaker directly on the bottom stand, at a 24" height. Smoothed out the highs perfectly in my setup that way.

Speaker positioning is a big part of making these speakers sound great, so it just takes some experimenting to find out what works best for each individual system.
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post #835 of 837 Old 07-03-2014, 12:10 AM
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LS50 owners,

Would like to know if anyone has paired their LS50 with Emotiva XPA-1L mono blocks? These mono blocks have a unique feature of operating as class A amp up to 35W (this is greater than the lower limit recommended by KEF's amp sizing blog) and switches to class AB beyond 35W up to 250W (which is beyond the upper 160W limit). One has to take care in prevent over driving the LS50+XPA-1L via the pre/pro.

When the amp is operating in pure class A mode, there is no switching at the zero point and hence no harmonic distortion (the odd order such as 3rd, 5th, 7th, 9th, etc.) that can cause listening fatigue. The downside to class A operation is that the transistors are operating all the time, hence the amp gets hot and is not very efficient.

So for low to medium level listening, I'm thinking this would be a nice combo; KEF LS50 + Emotiva XPA-1L. Currently Emotiva has the XPA-1L on sale to make way for the 2nd generation units.

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post #836 of 837 Old 07-03-2014, 03:24 AM
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Quote:
Originally Posted by steveting99 View Post
LS50 owners,

Would like to know if anyone has paired their LS50 with Emotiva XPA-1L mono blocks? These mono blocks have a unique feature of operating as class A amp up to 35W (this is greater than the lower limit recommended by KEF's amp sizing blog) and switches to class AB beyond 35W up to 250W (which is beyond the upper 160W limit). One has to take care in prevent over driving the LS50+XPA-1L via the pre/pro.

When the amp is operating in pure class A mode, there is no switching at the zero point and hence no harmonic distortion (the odd order such as 3rd, 5th, 7th, 9th, etc.) that can cause listening fatigue. The downside to class A operation is that the transistors are operating all the time, hence the amp gets hot and is not very efficient.

So for low to medium level listening, I'm thinking this would be a nice combo; KEF LS50 + Emotiva XPA-1L. Currently Emotiva has the XPA-1L on sale to make way for the 2nd generation units.
The meters on my amp rarely ever read higher than 1W of output so I'd think those Emotivas would be fine, as long as you're not in a huge room or trying to pretend the KEFs are a PA system.

Bill
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post #837 of 837 Old 07-09-2014, 06:10 PM
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So the NHT pedestals in my post above are the P5. Those are slightly shorter, narrower, and shallower and do not come with the outrigger feet that the P6 I ordered does. I just got them tonight so these are only initial impressions:
  • They're heavy - 3/4" MDF wrapped in some sort of veneer and weighing in at over 20 lbs.
  • They don't match exactly but they're damn close. They're the same shade of gray as the front baffle of the LS50 but they've got a metallic, car-like finish.
  • They're stable - MUCH more stable than the stands they're replacing.
  • With spikes on carpet and a bit of Blu-Tak in between them and the speakers they put the tweeters at 34" which is about an inch lower than my previous stands. I don't notice much of a difference in sound but the LS50s are fairly even off-axis so I'm not surprised.

They must have been NOS because they shipped from NHT's Benicia, CA address but that wasn't the user-name on eBay.





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