Brian Bunge
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Receivers with LFE 80Hz-Crossover, are Front Spkr sets missing their acoustic-mark (1 Viewer)
- Thread starter Paul A. Robinso
- Start date
Bryan Acevedo
Second Unit
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- Aug 7, 2001
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- 290
Let me clarify.
What I meant by full range was just a base reference level - not necessarily Dolby Digital Reference Level. It could be 80 db, or 70 db, or whatever - it is whatever level you are inputting to the amp.
So basically, what I am saying is that if you gave a speaker a test tone, that was at a constant of 80 db from 20 Hz to 20 kHz, and your speaker's -3 db point was at 32 Hz, you would get a 77 db output level at 32 Hz, and at 80 Hz it would be 80 db.
If it's -3 db point was say 70 Hz, then you would get 77 db at 70 Hz and 80 db at 80 Hz.
But then everyone assumes that the speaker has no output at 40 Hz. This speakers -12 db point could be at 40 Hz, we don't know unless we were to measure it. It could even be -6 db at 40 Hz.
So, lets say you take that full range signal I was talking about earlier, and you pass it through an 80 Hz High Pass Crossover. Now, at 40 Hz, this speaker only has to play a signal that is 12 db quieter than the rest of the signal. So it only needs to be able to play at 68 db at 40 Hz, which this speaker could be capable of, but we don't know only based on its -3 db point of 70 Hz. Some speakers roll off gradually, and some speakers roll off sharply.
So my point is that the whole assumption that a speaker with a -3 db point greater than 40 Hz will not work when passed through a 80 Hz High Pass Crossover does not hold up. This could be true in practice if the speaker couldn't even play a -12 db signal at 40 Hz, but I would guess that most can do this.
My guess is this is one reason why SVS doesn't rate their subs like this, as it is misleading and confusing. And the only thing that matters is what the speaker does in the real world, not on paper.
Bryan
What I meant by full range was just a base reference level - not necessarily Dolby Digital Reference Level. It could be 80 db, or 70 db, or whatever - it is whatever level you are inputting to the amp.
So basically, what I am saying is that if you gave a speaker a test tone, that was at a constant of 80 db from 20 Hz to 20 kHz, and your speaker's -3 db point was at 32 Hz, you would get a 77 db output level at 32 Hz, and at 80 Hz it would be 80 db.
If it's -3 db point was say 70 Hz, then you would get 77 db at 70 Hz and 80 db at 80 Hz.
But then everyone assumes that the speaker has no output at 40 Hz. This speakers -12 db point could be at 40 Hz, we don't know unless we were to measure it. It could even be -6 db at 40 Hz.
So, lets say you take that full range signal I was talking about earlier, and you pass it through an 80 Hz High Pass Crossover. Now, at 40 Hz, this speaker only has to play a signal that is 12 db quieter than the rest of the signal. So it only needs to be able to play at 68 db at 40 Hz, which this speaker could be capable of, but we don't know only based on its -3 db point of 70 Hz. Some speakers roll off gradually, and some speakers roll off sharply.
So my point is that the whole assumption that a speaker with a -3 db point greater than 40 Hz will not work when passed through a 80 Hz High Pass Crossover does not hold up. This could be true in practice if the speaker couldn't even play a -12 db signal at 40 Hz, but I would guess that most can do this.
My guess is this is one reason why SVS doesn't rate their subs like this, as it is misleading and confusing. And the only thing that matters is what the speaker does in the real world, not on paper.
Bryan
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