Discussion on matching of satellites to subwoofer

Ettepet

Novice Member
Ideally your speakers should be able to do frequencies well all the way down to as low as your subwoofer cut-off divided by 1.5. This means you'd need pretty good satellites.... (not talking about budget sollutions here of course ;))
 

Smurfin

Distinguished Member
Originally posted by Ettepet
Ideally your speakers should be able to do frequencies well all the way down to as low as your subwoofer cut-off divided by 1.5. This means you'd need pretty good satellites.... (not talking about budget sollutions here of course ;))
Eh?:confused: You're saying that with an 80hz cut-off frequency you need satellites which extend cleanly to 53hz? Someone tell me I read that wrong....:rolleyes:

If that is what you meant then imho you are sorely misguided. Some of the best systems I've heard have speakers which cut-off @ 80hz. My old M&Ks cut-off at that frequency, and my current THX pm3 approved actives do the same.
 

Ettepet

Novice Member
Originally posted by Smurfin
Eh?:confused: You're saying that with an 80hz cut-off frequency you need satellites which extend cleanly to 53hz? Someone tell me I read that wrong....:rolleyes:
You didn't read that wrong, but it might be too high-end a requirement for nearly all people out there. I just mentioned it to give some idea of an upper limit for such a quality product as the SVS sub. Sorry for causing you a heart condition.. :D
 

Jeff

Distinguished Member
It's a bit like saying that if you want a car so that you can constantly drive at 100mph you should go for a car that can do 150mph. It sort of makes sense a bit. But then not all speakers rated at 80Hz are the same ;)
 

Ettepet

Novice Member
Originally posted by Jeff
It's a bit like saying that if you want a car so that you can constantly drive at 100mph you should go for a car that can do 150mph. It sort of makes sense a bit. But then not all speakers rated at 80Hz are the same ;)
Not all speakers are, sure.

In this case it is all about the drop off that occurs at the lower bounds of the speaker and the one from the cut-off. These ideally shouldn't coincide, unless maybe to counteract a resonance in your room. Remember this is for high-end, not budget systems.

And yes, very few cars will drive comfortably at their top speed, unless that top speed is artificially lowered. :)
 

rags

Well-known Member
Ettepet - I sort of agree with you but it really depends on the speaker (otherwise we will all be buying floorstanders with 8 inch bass drivers just to get the headrom). The frequency responses quoted by certain manfacturers I am sure are bull**** anyway.
 

Ettepet

Novice Member
Originally posted by rags
And why would your rule of thumb only apply to high end systems only ???
I never said that! :D

But the topic is about what speakers match the SVS sub, and when "satellites" were mentioned I thought to step in a bit, as those are hardly a match.
 

rags

Well-known Member
Originally posted by Ettepet
Ideally your speakers should be able to do frequencies well all the way down to as low as your subwoofer cut-off divided by 1.5. This means you'd need pretty good satellites.... (not talking about budget sollutions here of course ;))

Originally posted by Ettepet
Remember this is for high-end, not budget systems.

Originally posted by Ettepet
You didn't read that wrong, but it might be too high-end a requirement for nearly all people out there. I just mentioned it to give some idea of an upper limit for such a quality product as the SVS sub. Sorry for causing you a heart condition.
I am not sure why :rolleyes: but somehow I get the feeling that you did.
 

Ettepet

Novice Member
I still didn't say it. You might try to read it in a way that it does, but I wasn't trying to sollicit as a lawyer.

And, I was trying to get the discussion on-topic again... ;)
 

Nimby

Distinguished Member
It should be remembered that speakers don't just stop dead at 80Hz. Or any other frequency in the bass. There is a slope, measured in dB per octave, that describes how quickly the speaker rolls off in the bass.

Different speakers roll off at different rates (or slopes). Infinite baffles roll off more slowly compared with reflex boxes. But reflex speakers usually go deeper for box size thanks to the port. This is a general rule not an absolute fact.

It is important that a speaker is able to reproduce frequencies well below 80 Hz or it won't be able to achieve -3dB (half power) at 80Hz. Many small speakers cannot produce enough deep bass to be able to roll off at 80Hz.

Normally (ignoring room effects) the main speakers should be at exatly the same audible output level as the sub when both are at -3dB in their roll off slopes. Both are then giving exactly the same contribution to the toal sound at that (-3dB) point as each other. <Whatever the volume level you are using>.

Active subs may have a steep (active filter) roll off slope to their upper frequncies to avoid too much mixing of their own sound with the other speakers. While the main speakers are still rolling off at their natural slope.

Turning up the volume affects the level of audible sound well beyond the cut-off point in the bass. The slope (dB per octave) remains exactly the same but lower points on the slope are raised to audible level. This assumes the speaker can produce anything worthwhile at these lower frequencies.

The human ear has its own roll off in the bass (and treble of course). This means bass has to be played louder than any other frequency to become audible <the deeper the bass goes>.

Which is why SVS & other powerful subs are so popular here. Because these subs play very deep bass without distortion at sufficiently high levels to become audible. Despite the ear's natural roll off in the bass.
They also overcome the small room's inability to allow deep bass standing waves to exist. So the room is pressure loaded instead. This takes a lot of power to pump enough air at very low frequencies.

I have never heard of the 1.5x factor but that doesn't mean it doesn't exist. It may well be a good rule of thumb given the average roll off slope slope for main speakers.

Hope this helps? :D

NIMBY
 

Jeff

Distinguished Member
Good post Nimby :)
 

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