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post #7321 of 7331 Old 05-02-2015, 11:31 PM
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Quote:
Originally Posted by steveting99 View Post
Use the following web app to determine the Sound Pressure Level (SPL) that can be achieved in your room with the Q900: http://myhometheater.homestead.com/splcalculator.html the goal is to reach 105dB peak at the Main Listening Position (MLP) - i.e. where you sit. Are you able to achieve this just in stereo mode?
That calculator is worthless, unless one is talking about listening outdoors or in an anechoic chamber. For more, better to point you here than to repeat myself.

Bottom line is really that Q900's demand very little from an amp, and chances are excellent that one's subwoofers are the limiting factor when using main speakers of that size and efficiency.

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post #7322 of 7331 Old Yesterday, 12:53 AM
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Originally Posted by DS-21 View Post
That calculator is worthless....
Do you have a better method / calculation to determine the relationship amp power, number of speakers, seating distance to MLP and speaker placement?

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post #7323 of 7331 Old Yesterday, 09:56 AM
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Originally Posted by steveting99 View Post
Do you have a better method / calculation to determine the relationship amp power, number of speakers, seating distance to MLP and speaker placement?
My method is simply not to obsess about things that are generally non-issues in real life with modern equipment and bass management.

But on Q900s, a friend of mine owns a pair. He, as many people affected by nonsense audiophool marketing claptrap, heard them on his AVR and insisted he needed a separate amp to get the best out of them. So he bought a Parasound amp that cost I think more than the speakers did. Objectively an excellent amplifier: high power, low noise, attractive faceplate. I offered to help him dial in the system after with the new amp. In the process, I snuck one of these cheap, old zone amps behind the thing and connected the Q900s to it. (I bought that amp for nearly nothing, and use it as a test amp for measurements, etc.) Needless to say, he enthused the amazing improvement offered by the amp - in everything from output to treble air to image centering! - over the AVR and wanted me to eat crow. I said I heard something that sounded like a bad connection, and asked him to check the connections. Red faces and valuable, four-figure-USD-saving lessons ensued.
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post #7324 of 7331 Old Yesterday, 10:46 AM
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Boy that's quite the story, it's almost believable. You had me up until "I snuck in a zone amp". Hahahaha

Now back to your regularly scheduled programming...

Hear me now, Listen to me later....
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post #7325 of 7331 Old Yesterday, 10:55 AM
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Quote:
Originally Posted by DS-21 View Post
My method is simply not to obsess about things that are generally non-issues in real life with modern equipment and bass management.

But on Q900s, a friend of mine owns a pair. He, as many people affected by nonsense audiophool marketing claptrap, heard them on his AVR and insisted he needed a separate amp to get the best out of them. So he bought a Parasound amp that cost I think more than the speakers did. Objectively an excellent amplifier: high power, low noise, attractive faceplate. I offered to help him dial in the system after with the new amp. In the process, I snuck one of these cheap, old zone amps behind the thing and connected the Q900s to it. (I bought that amp for nearly nothing, and use it as a test amp for measurements, etc.) Needless to say, he enthused the amazing improvement offered by the amp - in everything from output to treble air to image centering! - over the AVR and wanted me to eat crow. I said I heard something that sounded like a bad connection, and asked him to check the connections. Red faces and valuable, four-figure-USD-saving lessons ensued.
All that does...is prove; even a lowly, stand-alone separate amp...sounds better than an AVR. Just imagine, how much better his more-expensive Parasound unit would have sounded.

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post #7326 of 7331 Old Yesterday, 11:02 AM
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Boy that's quite the story, it's almost believable. You had me up until "I snuck in a zone amp". Hahahaha
Of course a salesman would interject something like that.

(The salesman who processed the return on the Parasound amp was not happy, either. )

A thinking person who understands what a 90+ dB/W/m speaker in a fairly standard size living room with bass management employed actually requires would understand why I did what I did, and that the result was inevitable. (The one question a thoughtful person might have is how I made the switch quickly and inconspicuously, considering that little amp has Phoenix terminals that require a screwdriver to terminate the speaker leads and not banana jacks or binding posts. The answer is a pigtail lead connected to one of these. I use this amp as a test amp when I'm measuring a loudspeaker outdoors, because I have no concerns about throwing it around. And the binding posts mean I don't have to use a screwdriver if I need longer speaker wire.)

The bottom line is that any marginal AB amp will be able to drive Q900's in a bass managed system to deafening levels just fine. They're efficient and a somewhat tough load. And a competent (load invariant, e.g. Hypex, Icepower, Anaview) Class D amp can too. Even one based on the little Icepower 50ASX2 (~25W/ch) in stereo mode.

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post #7327 of 7331 Old Yesterday, 04:25 PM
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My method is simply not to obsess about things that are generally non-issues in real life with modern equipment and bass management..
Think I've highlighted the key words in DS-21 point of using 25W per channel amps for his speakers.

Most modern receivers do have well implemented bass management system, the question then becomes what % of the power requirement is re-directed to the bass and is this dependent on the crossover freqeuncy.

There are readily available functions and a feature that would put the 25W per channel amp into risk of clipping and possibly damaging the speakers with high distortion.

(1) Room Equalization (REQ) that can reduce the gain stage by up to 9dB - if usiing a modern room correction algorithm such as Audyssey.
(2) PURE DIRECT mode. This is where the receiver disables bass management and sends the full range signals to the front left and front right amps.
(3) Party mode and/or all channel stereo mode. This where the 2.0 signal is sent to the surrounds and downmixed to the center channel.

I did an experiment with (1) + (3) and set the volume limit to 0dB (reference level) with the Marantz NR-1504 receiver. The setting on the receiver was bass management enabled, all channel stereo. Had the sub crossover frequency on the high side - 100Hz. Maximum distance to MLP was just over 10'. The NR-1504 is rated at 50W per channel in stereo mode with very low distortion and was placed in an open area with sufficient space around it for cooling. Was playing around with a few tunes during the evening and noticed the compression in the KEF E301, but it was late and had to work the next day.

Got a complaint from the wife the next day saying the receiver keep shutting down (due to thermal protection) while she was streaming tunes using Spotify and had the volume turned up. I repeated her experiment and shure enough she was right. Had to place a lower limiter on the receiver to -10dB so that the unit would not go into thermal protection. The wife is now happy since she can now stream her tunes.

When using the web app, found out that 50W per channel was NOT sufficient.

So my experience is very different from yours.

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post #7328 of 7331 Old Yesterday, 06:07 PM
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Originally Posted by steveting99 View Post
Think I've highlighted the key words in DS-21 point of using 25W per channel amps for his speakers.
For the record, they're not my speakers. (I do use the 8" Uni-Q from the Q900 in my desktop speakers.) The only KEF speakers currently in my main system are R800ds surroundThe Q900's have really great bones, but the cabinet quality is not sufficient for my living room, and the crossover needs to be reworked to let that amazing 8" Uni-Q shine. (Could probably get 90% of the way there with a notch filter to tame the midwoofers' breakup. One of those things I've planned to get around to doing at some point. Hard to take measurements of large speakers in someone else's living room when they have a toddler, though...)

In fact, on my speakers I actually use a fairly expensive separate amp capable of greater than 200W into 8Ω with all channels driven. Why? Because I want to. I make no claims of sonic superiority for it, except that its noise floor is so low it had no trouble powering 96dB/W/m speakers at a short listening distance. I just wanted it.

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I did an experiment with [an obsolete variant of Audyssey known for doing even more nasty things to the treble than their current XT32 version] + [all channel "stereo"] and set the volume limit to 0dB (reference level) with the Marantz NR-1504 receiver. The setting on the receiver was bass management enabled, all channel stereo.
First, I assumed a standard mode (stereo, surround sound expansion by something like DPL2, discrete multichannel) not a no-fi sound spraying setup.

OK...now please explain to everyone how willfully
-using a tiny (and thus lower thermal capacity, given its Class AB amps) AVR
-in a no-fidelity mode
-to drive tiny low efficiency speakers with tiny cones backed up by basically no cabinet volume below their capabilities

has to do with

-using a standard AVR or AVR-grade AB amp (the Sherbourne I used in this particular case was below AVR grade, admittedly)
-in a mode worth of good audio gear
-to drive fairly large and high efficiency speakers with fairly large cone area operating in a fairly large cabinet volume?

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Originally Posted by steveting99 View Post
Had the sub crossover frequency on the high side - 100Hz. Maximum distance to MLP was just over 10'. The NR-1504 is rated at 50W per channel in stereo mode with very low distortion and was placed in an open area with sufficient space around it for cooling. Was playing around with a few tunes during the evening and noticed the compression in the KEF E301, but it was late and had to work the next day.
I can see how that must've sounded awful. The E301 eggs (I recently picked up a pair, FWIW, for potential immersive heights; I have a bunch of the predecessor HTS3005SE, but they're all black so they would not look good mounted as heights in my living room. The E301's are white.) cannot play that low without serious dynamic compression regardless of power in a space bigger than a BMW X5. It doesn't matter if there's a chipamp or an ATI AT6000 driving them. It's a matter of tiny tiny cone, and motor that gets very hot because the egg has basically no airspace in it. The older HTS3001SE was a little better in that regard, even though I believe the midrange's voicecoil was considerably smaller-diameter. There was just more room in there because the driver motor was much smaller. Neo slug rather than giant ceramic disk. But I still highpassed 'em at 120Hz. See "modest multisubs" thread.)


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Originally Posted by steveting99 View Post
So my experience is very different from yours.
I agree, but that's because your starting conditions are not ones I would consider reasonable use of good audio gear. Use your system like someone who cares about how music sounds (no all channel "stereo" silliness, a highpass appropriate to the mains speakers) and/or pick an AVR that's not inherently a marginal performer because of the design choices made (lotsa heat-producing stuff - HDMI boards, AB amps - in a very compact case) and you might come around to my view.

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post #7329 of 7331 Old Yesterday, 06:33 PM
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I tired the 25W Nad 7050 D with a pair of Kef LS50s. It was a bad combo. The LS50s aren't 90db efficient though. I had to turn the volume all the way into the +side for any decent, not even loud, volume. A 70W Marantz integrated worked wonderfully though. I could A|B them with my Paradigm S2. The difference in efficiency between the two speakers was striking.
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post #7330 of 7331 Old Yesterday, 07:45 PM
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Originally Posted by DS-21 View Post
...

First, I assumed a standard mode (stereo, surround sound expansion by something like DPL2, discrete multichannel) not a no-fi sound spraying setup.

OK...now please explain to everyone how willfully
-using a tiny (and thus lower thermal capacity, given its Class AB amps) AVR
-in a no-fidelity mode
-to drive tiny low efficiency speakers with tiny cones backed up by basically no cabinet volume below their capabilities

has to do with

-using a standard AVR or AVR-grade AB amp (the Sherbourne I used in this particular case was below AVR grade, admittedly)
-in a mode worth of good audio gear
-to drive fairly large and high efficiency speakers with fairly large cone area operating in a fairly large cabinet volume?
Thought the we were discussing amp power requirements for KEF speakers in room - or is it going off tangent now? Your previous post says that the web app for determining power requirements based on a number factors is "worthless", I disagree as there is no real good alternative tool. I note that KEF doesn't give both the anechoic speaker sensitivity as well as in-room sensitivity numbers. Speaker manufacturers that do give both anechoic and in-room speaker sensitivity numbers, the in-room numbers are always higher. I ASSumed KEF's numbers are in-room. Maybe this is a bad thing to ASSume since I don't know how KEF tested their speakers?

So I ask again, how would one determine amp power requirements based on in room speaker sensitivity, the number of speakers, seating distance to MLP and speaker placement in the room? Avoiding the question doesn't provide a satisfactory answer. I'm on the lookout for a better tool to use - if there is one.

The fundamental question is that of risk. Having sufficient power or over driving the amp into clipping and leading to potential damage of the speakers? Most consumers would not know how to gain match components within the audio chain. The ordinary Joe would not know the passive speaker crossover design and power split between woofer to mid-range + tweeter. Do you? If so, what is the engineering basis with bass management electronic crossover implemented in the pre/pro/receiver? Would like to know the power split based on the electronic crossover selected on the pre/pro/receiver.

The basis of your claim on the "worthless" web app is that it over estimates the power requirement for the amp. For pure 2-channel stereo mode, i.e. without bass management, this is good enough to get an approximate power figure. A check against the amp/receiver's capabilities for clean maximum power is a sensible thing to do. So I disagree with you on this point that the web app is "worthless".

What you're implying is that less than 50W per channel is all that's needed to get to reference levels provided one ALWAYS enables bass management and not use any of the available functions because you consider them to be "...no-fi sound spraying setup" How did you determine that PURE DIRECT/DIRECT mode to be "no-fi sound spraying setup"? There are people who do enjoy playing tunes in pure stereo mode using just their front left and front right speakers as the noise makers. That's been the case since stereo was developed from mono.

An actual test case was used to show that less than 50W per channel system failed with bass management and unable to maintain reference level. It is a repeatable test. The all stereo / party mode feature is available on every modern receiver so that anyone can do this test. Results may and will differ for each room/setup. You may not want to use this feature for what ever reason, but if one was having a house party - this feature would be useful. Image the look on everyone's face when the receiver goes into thermal protection mode and the music stops. A non-functioning setup is the same thing no setup. Who is/are having the red face(s) then? It may not be you, but others might want to consider this risk.

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..I agree, but that's because your starting conditions are not ones I would consider reasonable use of good audio gear. Use your system like someone who cares about how music sounds (no all channel "stereo" silliness, a highpass appropriate to the mains speakers) and/or pick an AVR that's not inherently a marginal performer because of the design choices made (lotsa heat-producing stuff - HDMI boards, AB amps - in a very compact case) and you might come around to my view.
The starting conditions have changed. Going to get some mid-bass modules from Rythmik to complement the E301 with Dirac Live REQ + Atmos setup. Have purchased additional speakers + external amps. See my signature below.

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Last edited by steveting99; Yesterday at 10:47 PM. Reason: typo
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post #7331 of 7331 Old Today, 08:50 PM
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Thought the we were discussing amp power requirements for KEF speakers in room - or is it going off tangent now?
The question was as follows: "Hello, I just bought a pair of KEF Q900's a *** does anyone have any suggestions for a separate multi-ch amp, how to connect it and potential benefits over what I'm using?"

So no, not power requirements for KEF speakers generally. Power requirements for Q900s specifically. Power requirements for a brand of speakers generally is not something I would comment on, because it's a stupid question to ask.

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Your previous post says that the web app for determining power requirements based on a number factors is "worthless", I disagree as there is no real good alternative tool.
That's not a reasonable point of disagreement. Here's basically the exchange:
Me: There's no spaceship that can get a man to Mars, so you shouldn't use a current model spaceship to try to go to Mars.
You: I disagree as there is no real good alternative ship. So we should use this one that we know is not going to get us anywhere close anyway.

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I note that KEF doesn't give both the anechoic speaker sensitivity as well as in-room sensitivity numbers.
That's because those aren't two real things. There is sensitivity, which is conventionally defined as output either on pink noise or over a defined bandwidth at 2.83V, measured at 1m. Besides that, anything else is a pointless BS spec made up by marketers for the technically illiterate.

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So I ask again, how would one determine amp power requirements based on in room speaker sensitivity, the number of speakers, seating distance to MLP and speaker placement in the room?
One who knew what s/he was talking about would not attempt to do that, because the variables make no sense.

"In room speaker sensitivity" is not a real thing except in the eyes of technically illiterate marketers.

Number of speakers is irrelevant.

The effect of speakers and seating distance on SPL falloff depends on the room.

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Avoiding the question doesn't provide a satisfactory answer. I'm on the lookout for a better tool to use - if there is one.
I'm not avoiding the question, I'm answering it directly: there is no such tool, because it's not a reasonable thing to expect an online calculator to provide.

Also, obsessing about amplifier power is stupid. Smart people don't do it. One will know if s/he has too little power easily, by listening. Clipping is audible, though less experienced people may confound speaker output or linearity problems with amp power problems.

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The fundamental question is that of risk.
No, the fundamental question is one of obsessing about something that's generally a non issue.

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Originally Posted by steveting99 View Post
The basis of your claim on the "worthless" web app is that it over estimates the power requirement for the amp.
No, the basis of my claim is that it ignores material variables, and the variables it uses are only useful outdoors or in an anechoic chamber.

That it overstates power requirements is factually correct, but completely irrelevant to my claim that it's worthless.

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Originally Posted by steveting99 View Post
How did you determine that PURE DIRECT/DIRECT mode to be "no-fi sound spraying setup"?
That comment was about all channel "stereo," not playing two channel program material over two channels.

Quote:
Originally Posted by steveting99 View Post
An actual test case was used to show that less than 50W per channel system failed with bass management and unable to maintain reference level.
An actual test case really just showed that a tiny tiny speakers can be overdriven when misused, and that a very compact budget AVR model has insufficient heat-sinking for an HDMI board and a multichannel AB amp asked to run full-tilt. Nothing more.

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Originally Posted by steveting99 View Post
but if one was having a house party - this feature would be useful.
I would never insult my guests, my ears, or my equipment by using an all channel "stereo" mode.

Do you even know what "stereo" means? It has nothing to do with the number of channels. (Stereo was actually a 3-channel format until it was degraded to 2 channel so that stereo recordings could be cut into vinyl records.) "Stereo" means "solid," as in creating a soundstage. IOW, "stereo" is a synonym for "imaging." The very thing that playing the same content at the same level completely destroys.

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Originally Posted by steveting99 View Post
The starting conditions have changed. Going to get some mid-bass modules from Rythmik to complement the E301 with Dirac Live REQ + Atmos setup. Have purchased additional speakers + external amps. See my signature below.
Why not sell those cockamamie servo things and buy competently-designed subwoofers with adequate bandwidth?

As for the broken link, my apologies. Try this: Measurements of a modest multisub setup in a temporary rental apartment

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