How do inadequate speakers handle low Hz?

[Trace79]

I'm just curious as to what happens when my speakers that are rated to go down to 64Hz get signals lower than that? Will they not play the sound at all? Or is it more of a roll-off? I know 64Hz isn't much for handling low frequencies at all but to me it seems these (Tannoy 501A studio monitors,) do really well at low freqs for only having a 5" driver. They were a night and day difference when sampling them at Guitar Center vs. the KRK Rokits, Mackies, and Yamahas. But I can tell there are low-end frequencies mixed in the recordings that I'm just not hearing properly. My SVS PC12-NSD sub is almost here so I'm wondering if I'll be hearing totally new sounds in the low-end once it's hooked up or just more clearer and stronger output from what I can already hear with the Tannoy monitors?

Thanks in advance.

 

[monkish54]

Will they not play the sound at all? Or is it more of a roll-off?

I think it's either the drivers natural roll-off, or they put a high pass filter to help roll the low frequencies even faster. I'd guess the former is the most common.

I'm wondering if I'll be hearing totally new sounds in the low-end once it's hooked up or just more clearer and stronger output from what I can already hear with the Tannoy monitors?

Interactive Frequency Chart - Independent Recording Network

According to this chart you should hear a little bit more of the Tuba, Harp, and Bass.

You should also feel the bass more. About 60hz down is when you start to really feel the bass.

 

[agarwalro]

Further to what Monk said, if there is insufficient roll-off or someone intentionally sends excess power to the driver, the following will happen as power increases,

1. Distortion increases and sound quality goes down
2. Driver physical travel limit (X max) is reached and you hear DubStep like sounds, aka, bottoming out
3. Driver thermal limit is exceeded and voice coil melts (smoked) or X max is exceeded and driver rips itself apart (blown)

 

[monkish54]

[*]Distortion increases and sound quality goes down
[*]Driver physical travel limit (X max) is reached and you hear DubStep like sounds, aka, bottoming out

Just a small correction:

Xmax is the linear travel of the driver.

Xmech is the mechanical limit. Once you reach Xmech...damage is happening.

Xmax/Xmech--------Short for Maximum Linear Excursion. Speaker output becomes non-linear when the voice coil begins to leave the magnetic gap. Although suspensions can create non-linearity in output, the point at which the number of turns in the gap (see BL) begins to decrease is when distortion starts to increase. Eminence has historically been very conservative with this measurement and indicated only the voice coil overhang (Xmax: Voice coil height minus top plate thickness, divided by 2). Xmech is expressed by Eminence as the lowest of four potential failure condition measurements times 2: Spider crashing on top plate; Voice coil bottoming on back plate; Voice coil coming out of gap above core; Physical limitation of cone. Take the lowest of these measurements then multiply it by two. This gives a distance that describes the maximum mechanical movement of the cone.

 

[j_garcia]

The speaker will play to the point that it mechanically cannot reproduce the sound any longer. As was mentioned, it will still attempt to play those sounds and if you push it too hard, the result could be damage to the speaker. There is typically no high pass filter in a speaker to control the lower limit (other than Bose, I've never seen that done). It is the natural roll off of the design of that driver in that box/alignment.

 

[JerryLove]

But within the speakers rated power, the presence of a 20Hz signal should not damage the speaker (if it's designed competently), and steps should have been taken to prevent signifigant distortion (if it's designed well).

You should just get less volume below the specified frequency: approaching effective 0 pretty rapidly in most speakers.

 

[monkish54]

But within the speakers rated power, the presence of a 20Hz signal should not damage the speaker

Yup! To add to Jerry: It's not the frequency that is an issue, it is the power level and amount of exertion necessary to amplify that frequency to a specific level.

Take the Dayton 2" for instance. If you play some music through the speaker with no crossover, it will still be playing the content at 100hz, but it will be down in level by 30db! Imagine the amount of exertion & power level needed to play 2khz at 90db at 12 feet, imagine the heat created in the VC. Now imagine trying to play 100hz at 90db through that speaker! That would be the equivalent of playing that 2khz tone at 120db!! To play 120db at 12 feet with that driver, you would need 11,000 watts. That is slightly over the 60 watt RMS the driver is happy handling. :O That would turn that driver into LIQUID **** and drive it WELL past Xmax, Xmech, and Xsus. Hell, the spider and surround will probably tear apart and the diaphragm will fly off...if it doesn't melt first!

 

[j_garcia]

But within the speakers rated power, the presence of a 20Hz signal should not damage the speaker (if it's designed competently), and steps should have been taken to prevent signifigant distortion (if it's designed well).

You should just get less volume below the specified frequency: approaching effective 0 pretty rapidly in most speakers.

Yes, that too It is not like you would send a 20Hz signal to a speaker that has a -3dB of 65Hz and it would fry, it simply won't play it. If there is something within the physical range of the speaker however, then it may present an issue.