Worst case I know of is someone pulling up a document for having an italicized full stop. Sadly he didn't really read the technical content!
I worry about that metric, at least for classical as many pieces have significant quiet sections that a simple RMS calculation will not show. But it does roughly align with THX/Red book. I reckon 99% of my listening cases would be covered with 85dB at -20dBFS with attenuation down from that for genre/time of day. 10dB for normal listening (classical) 20dB for modern studio stuff (sob) and 30dB for late at night.
If you were that worried your listening room would be designed for quiet aircon or you would live in a more human friendly isocline.
panels of arrays help here 🙂
Other than exotics like I would have if I had the space 82dB/W would suggest someone trying to squeeze bass out of a tiny woofer in a tiny box. If you listen to LS3/5a at 3m you deserve everything you get.
What interests me is whether active gives you a lot more flexibility below 200Hz. There are a lot of long throw sub units you can look at once freed from the tyranny of trying to match efficiencies across 3 drivers.
Daniel, congratulations in advance- you'll do fine. Just remember that you know more about the subject than anyone on your committee.
Bill, the LS3/5 is a rather good loudspeaker, but also oribably one of the most misused speakers in the world. Ot is exactly what its name says, a monitor loudspeaker, initially developed for BBC report vans, where space is at a premium. Using it in a normal room is asking for trouble because it has virtually nothing below about 100 Hz. Meaning that if you really want it in a room with full range, two subwoofers become mandatory, or you need to change to BBC's bigger monitors, as are those from Rogers et al. Buy a Spendor BC3 instead, it's a speaker to die for.
My experience is that for in room loudness you need speakers and amps which can together produce no less than 112 dB at 1 m. Then your chances of hitting some compression will really be quite minimal, even with super recordings.
Assumig that is so, and that you have a nominally 100W/8 amp, which is 20 dBW, then your speaker would need an effiviency of (112-20) 92 dB/1W/1m. In real life, you will exeperience a loss across the XO of at least 1 dB at increasing levels, so it would be wise to have an amp rated at 21 dBW, which is app. 125W/8, which is almost eaxctly what John is doing. My own H/K P2400 is guaranteede a mnimum of 170W/8, which is (rounded off) 22 dBW, and my speakers are rated at 92 dB/1W/1m, so I have a theoretical pressure of (92+22-1) 113 dB SPL/1m, or (113-6) 107 dB SPL at 3 meters.
Since renovating the apartment two years ago, my new windows offer excellent sound proofing (I live on the 8th floor above a very noisy street, the city dweller's curse) my ambient noise has decreased to 37-38 dB, leaving me a dynamic range of potentially (107-38) 69 dB, not ideal, but reasonable enough. I could improve that by maybe 2 dB if I use biamping as that would reduce XO losses by going active and outside the speaker box.. Just DON'T ask me what those windows cost me (aluminium frames, sound proofing, etc).
Assumig that is so, and that you have a nominally 100W/8 amp, which is 20 dBW, then your speaker would need an effiviency of (112-20) 92 dB/1W/1m. In real life, you will exeperience a loss across the XO of at least 1 dB at increasing levels, so it would be wise to have an amp rated at 21 dBW, which is app. 125W/8, which is almost eaxctly what John is doing. My own H/K P2400 is guaranteede a mnimum of 170W/8, which is (rounded off) 22 dBW, and my speakers are rated at 92 dB/1W/1m, so I have a theoretical pressure of (92+22-1) 113 dB SPL/1m, or (113-6) 107 dB SPL at 3 meters.
Since renovating the apartment two years ago, my new windows offer excellent sound proofing (I live on the 8th floor above a very noisy street, the city dweller's curse) my ambient noise has decreased to 37-38 dB, leaving me a dynamic range of potentially (107-38) 69 dB, not ideal, but reasonable enough. I could improve that by maybe 2 dB if I use biamping as that would reduce XO losses by going active and outside the speaker box.. Just DON'T ask me what those windows cost me (aluminium frames, sound proofing, etc).
I used the LS3/5a example as it was 82dB/W. Can't think of anything else that inefficient other than my Apogee hybrids (which are rare and unusual) and super-high-end stuff. But even those, once freed from the tyranny of the passive x-over gives me an 89dB woofer and a ribbon that is a benign resistive load.
The first and only time I heard that track was on a pair of KEF KM-1 in a reasonably large room. I must admit that I was fairly impressed. 🙂
Mogens
I am not much better off myself, Bill. The measured distance from either speaker is just a bit more than 2.5 meters, with 4m between the speakers. Fortunately, both stand at exactly the same distance from me, and relative to the floor (custom furniture helps here, add spikes and you're just fine, no overblown bass). The reflex port is on the back of the speakers, and right benhind them are thick cotton curtains with next to zero reflexion. If anything, this tends to thin out the bass lines, rather than inflate them.
The one and only misgiving I have is the fact that the system is located to the right of the right speaker, dictating a distance of almost 6 meters from the system to the left speaker, necessetating very thick wiring (van den Hul, CS352, 5.5 sq,mm, a mix of silver plated OFC copper and carbon fibre 2*254 strands). But all the slam I want is there if present in the incoming signal.
Bet you don't have this http://www.amazon.com/Baby-Diego-CubZone-Playpen-Activity/dp/B00B49IQPM to deal with floor bounce tho 🙂
I have my speaker facing the opposite wall, which makes the wall sound like a stage. Does that mean my distance from the speaker is longer than the width of my room?
Kindy,
I suspect a few professional typists still exist, hopefully happily retired. The closest equivalent would be a graphic designer today.
Billy,
My ambient noise level runs below 10 dBa. However measuring this is a bit difficult as with a handheld meter I have to hold my breath.
In most real rooms even if you are 3M away from the loudspeaker bounce off of the wall behind you will raise the level. Inverse square law meets it's match indoors.
The issue is not so much loudspeaker efficiency as it is boosted bass levels to make the volume across the frequency spectrum match. That does take more energy. As to listening volume based on audience experiments the minimum is 70 dBa.
Derfy,
It is a shame you can't tell when I am serious. SO WHEN I AM..... You really should consider letting Brad get a peak at your latest comic book. If he doesn't scream it may increase your confidence.
There is certain to be someone on your panel who is convinced they know more than you or your advisor and will want to be sure you know that.
Or as the advice given to the folks just before going to the firing squad, "Relax, doesn't matter how many guys are shooting at you, the only guy who counts has a whistle."
That should be your advisor.
I suspect a few professional typists still exist, hopefully happily retired. The closest equivalent would be a graphic designer today.
Billy,
My ambient noise level runs below 10 dBa. However measuring this is a bit difficult as with a handheld meter I have to hold my breath.
In most real rooms even if you are 3M away from the loudspeaker bounce off of the wall behind you will raise the level. Inverse square law meets it's match indoors.
The issue is not so much loudspeaker efficiency as it is boosted bass levels to make the volume across the frequency spectrum match. That does take more energy. As to listening volume based on audience experiments the minimum is 70 dBa.
Derfy,
It is a shame you can't tell when I am serious. SO WHEN I AM..... You really should consider letting Brad get a peak at your latest comic book. If he doesn't scream it may increase your confidence.
There is certain to be someone on your panel who is convinced they know more than you or your advisor and will want to be sure you know that.
Or as the advice given to the folks just before going to the firing squad, "Relax, doesn't matter how many guys are shooting at you, the only guy who counts has a whistle."
That should be your advisor.
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70dBa what tho? ref -20dBFS or uncompressed music RMS?
As for bass
1. I have realistic expectations from a room that is basically a 12' cube with added challenges
2. I have 12" of infinity's finest servostatic where I need that little extra
3. New movie trailers at the local cinema have the bass so high I feel queasy. If that is correct I don't want it!
4. I've lived with little below 100Hz for so long I'm used to it.
Checking what JC meant by having THX ultra accreditation I came across this THX Loudness Plus THX.com which made me smile as its admission that THX reference is too loud unless you have a dedicated and sound proofed home cinema.
dBa SPL
The reference is 20 uPa. The weighting is "A". The meter is set for "Slow" averaging.
Or about as loud as 1,000,000 mosquitos swarming around you.
BTY Just checked my office with music on is about 41 dBa SPL.
Sorry, need to be monosyllabic
70dBa against what. top 40 pop music will have a DR of 4 or 5 so that will be around -6dBFS. Nice music might be -40dBFS. At your 70dBa what would 0dBFS give you without touching the volume knob?
70dBa against what. top 40 pop music will have a DR of 4 or 5 so that will be around -6dBFS. Nice music might be -40dBFS. At your 70dBa what would 0dBFS give you without touching the volume knob?
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