HiFi+ goes digital and multichannel!

It's possibly difficult to generate two similar waveforms at a precise and adjustable phase difference with most signal generators. And they're usually not calibrated in rpm...

Whereas almost everybody has a PC with a soundcard. And once you've decided what phase sounds best you cut a CD and put that expensive player to a proper purpose.

Paul
 
Originally posted by Paul Ranson
So now 50Hz is inaudible?
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Paul, 50Hz is, of course, audible. However, its location is not generally detectable, which isn't surprising as its wavelength is just under 22 feet.

Confusion is this area is rife though, especially when people are discussing the ability to detect the location of subwoofers. This is complicated by the purity of the sound made by the speakers and the amplifiers, etc. (higher harmonics will often be directional). Vibrations from the sub's enclosure are also a give-away as to position.

I also believe (although it isn't often cited) that the size of the listening room makes a difference to the frequency that is directional. In a smaller room the frequency would need to be higher before its location could be detected.

I suspect that lowrider is right and that the higher frequency harmonics are giving away the position of the power amps buzzing.
 
Thanks Steve,

Thats exactly what I mean... :D

I use 60hz xover because in my room I can detect the subwoofers at 80hz... :rolleyes:
 
50Hz is, of course, audible. However, its location is not generally detectable, which isn't surprising as its wavelength is just under 22 feet.[/quote
A quick test with pure 50Hz shows that the general area of emanation is clear. I don't know what the location mechanism is perhaps my speakers hideously distort at low levels of 50Hz.

It also showed an interesting left/right asymmetry which I will have to investigate.

I think perhaps we have to get down to actual subsonics before directionality truly disappears.

Try it for yourself, as the general advice goes....

Paul
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Even with the "general" area of emanation being clear, the sub is close enough not to be heard, still, I bet if you analyse the sound, you will have some harmonics... :rolleyes:
 
By 'general area' I mean I can determine left and right coming from the direction of my loudspeakers. Due to the nature of my signal generation I couldn't do a full sweep.

So I need two subs, located near the main speakers...

Paul
 
Thats what I have and recommend, but one somewhere between the speakers wont make itself too obvious, if it is properly setup, and xover up to 60hz... :MILD:

Also, I hear that deep bass is usually mono, same from both stereo speakers, I wonder if that is true... :rolleyes:
 
Last edited by a moderator:
Originally posted by lowrider
Thats what I have and recommend, but one somewhere between the speakers wont make itself too obvious, if it is properly setup, and xover up to 60hz... :MILD:

Also, I hear that deep bass is usually mono, same from both stereo speakers, I wonder if that is true... :rolleyes:
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There are two issues to the 'deep bass is usually mono' question and they should be considered separately.

Firstly there's the recording. Generally, on LPs deep bass is in mono whereas on cds it can be recorded in stereo.

Secondly there's the question of at what frequency we can detect the location of the bass. This depends on room size (I believe) and in practice also depends on the steepness of the crossover slope, speaker and amplifier distortion and speaker cabinet. In other words, when we play a frequency of, say, 60Hz, we may be hearing harmonics at 120 and/or 180Hz and it may also excite cabinet vibrations (and standing waves). This will give us location information that we wouldn't get with a pure tone.

If the subwoofer content is really below 60Hz (with a reasonably steep crossover slope and low distortions, resonances and vibrations), you could place the subwoofer in a room corner and not detect its location. Corner positioning will excite the room modes and give a louder output. This may be a good thing, particularly if you're using equalization, as it's easier to remove the peaks than to fill in the troughs and the extra efficiency is useful.

If I've said it once I've said it a thousand times, there's no such thing in hi-fi as .... wait a minute, you're just winding me up lowrider, aren't you?

Ok, cancel all of the above.
 

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