Tannoy F1 Custom speakers: distance from wall (Update)

Dazmb

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I'm interested in these speakers after the 2007 WHF award result. I've seen the article in WHF, and their advice not to place too near walls. Now i'm no hi-fi expert, but why is this a problem with front porting speakers. Surely the very purpose of front porting is to avoid 'booming' from walls as you would never have them pointing at a wall?

Tannoys own leaflet says back of speaker ideal distance from wall is 0.5m's. That seems a huge gap for a compact speaker to have to be optimal. I simply don't have that much space available to give them between my wall and where I sit (directly in front of them about 2m's away with speakers toed-in).

Will I suffer bass bloom/boom if they are closer? I can spare them 0.20m's max...

Any guidance appreciated, cheers.
 

Dazmb

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They are about 2m's apart from each other Andrew (not the widest soundstage I know...), and have 1+m's free to the side walls (although the left speaker is close up to my CRT telly).
 
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Anonymous

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Room acoustics and speaker placement is a very unpredictable thing it amazes me how complicated a frustrating it can be, and how a speaker will respond in a certain position with a room, but i've found unless the speakers is moffit? hope thats the correct word, or designed to be be placed hard against a wall, a speaker in general sounds better well away from the walls, especially in a smaller sized room, if you are concerned get a freq sweep test disc, a SP Metre to record the results and see where the bass response is most satisfactory in relation to the walls.
 

gregory

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rega r1 work close to a wall but they may be over budget,the other members are right though all speakers work better away form walls there are exceptions to the rule like omnidirectional speakers but then its a different ball game.
 

Dazmb

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Have bought QA 1010's reading another good web review... Couldn't risk the T F1C's as the dimensions just seemed too big.

Hope I don't regret it after reading the WHF £150 supertest in the next few days!
 

Andrew Everard

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[quote user="Dazmb"]

Hope I don't regret it after reading the WHF £150 supertest in the next few days!

[/quote]

emotion-16.gif
 
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Anonymous

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Sound resonates in all directions from a speaker... you can still hear it when it's facing away from you. You might notice the treble is quietened and the bass not so in this situation though, because cabinet resonance is also one of the producers of the bass, not just the air moved by the driver. Anyway, the wavelength of a bass note (say 55Hz, which is 3 octaves below concert pitch A) is measured in meters.

At 55hz you have a wavelength (given the speed of sound as 330m/s) of 330/55=6 metres. So what happens is that when you place the speakers near the wall is that the sound is reflected back (at say, 50cm from the wall) 1m out of phase. Also, given the distance it's moved it will have attenuated according to the 1/r squared principle.

So at your listening position (say 2 meters in front of the speakers), you have two 'bass notes' coming your way. One that is the original speaker output that has attentuated to 1/4 the sound pressure level you'd hear at 1m from the speaker. The other is the reflected wave off the back wall. This wave is 1 meter out of phase.. with a wavelength of 6m this will interefere constructively giving you more bass. This waveform is 1/9 the intensity though.

Sounds like I've just spelt doom for having a speaker anywhere near a wall at all ever, but thats not the case. Firstly, the wall is not going to relfect 100% of the sound, secondly, the speaker designer is well aware that this will happen and will design the unit to mask this effect and thirdly, something I didn't take into account above (because I don't know the numbers) a speaker does not produced an equal amount of sound going backwards as it does forwards. Audio is directional, it's just bass notes are very good at diffracting aorund objects and hence will get around doors and walls and chairs etc without attenuating nearly as much as treble would. (hence wall proximity effects the bass and not much else).

That's the crux of it anyway, imagine your living room is filled with water up to the level of your speaker cones. Start playing music and watch what the waves created in your 'living pool' do. Air is a fluid just like water is.
 

Dazmb

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Hmmm ... Ok, so having spent my £4.10 on WHF today I take it I can be happy that the old version 1010's I should recieve are better than the new 1010i's which you seem not to like?
 

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