Basic question about PEQ

[shkumar4963]

Can I use PEQ to lift bass response of a standmount speaker? If yes, what is the limit of this approach? How much increase at lower frequencies (in db) is accoetable? For a speaker with -6db point at 50 hz and -12 db at 32 hz, can I raise 12 db using PEQ for a flat frequency response till 32 hz. That would be sufficient for all kind of music except for home theater. one negative could be danger of burning the speaker by pumping so much energy in the speaker at that low frequency. How do I estimate what is the max energy I can put in the speaker safely? For average music listening levels ( about 86 to 90 db at 1 m), is there a danger for kef ls50.

 

[BoredSysAdmin]

the right way to use any EQ is to lower the signal in order to improve it's response, LS50 is ported speakers, trying to EQ it below it's F3 (at 79hz) is at best futile exercise.
You've already spend around $1.5k for great speakers. The right thing to do in order to improve bass is to get good subwoofer. Which one - depends on room size, budget and how loud you like it to play, but as general rule - everything below $500 is not matching with KEF LS50

 

[shkumar4963]

"trying to EQ it below it's F3 (at 79hz) is at best futile exercise" I understand your recommendation. I was more looking for a scientific explanation for why or why not it can be done.

 

[BoredSysAdmin]

"trying to EQ it below it's F3 (at 79hz) is at best futile exercise" I understand your recommendation. I was more looking for a scientific explanation for why or why now it can be done.

Lets hope that @TLS Guy has a second to reply to that question.

 

[slipperybidness]

Short answer--You are fighting a losing battle!

It would take tremendous amounts of power to bump up the response below the tuning frequency. If you put that much power continuously through the voice coils, you will fry them.

 

[ski2xblack]

"trying to EQ it below it's F3 (at 79hz) is at best futile exercise" I understand your recommendation. I was more looking for a scientific explanation for why or why not it can be done.

If your mains are sealed, you will require excessive eq and power applied. Distortions associated with cone motion will increase.

If you mains are ported, below port tuning the driver and port go out of phase, thus lots of cone movement but no increase in sonic output.

In both cases you increase the risk of pushing the drivers out of their safe operating area.

 

[shkumar4963]

Without knowing xmax for ls50 bass driver, it is probably not possible to know if PEQ will work or not above the port frequency (50 hz). Below the port frequency PEQ may not be as effective but again depending on the xmax, PEQ may be somewhat effective.

 

[markw]

Trying to get a loud 32 hz tone from a 5" speaker is an exercise in futility and petty much guarantees the death of an otherwise fine speaker. If that's what you want, go for it but a subwoofer would be a much better, and effective, solution.

When you consider that to get an effective doubling of the acoustic output (about 10 decibles), you need TEN times the power. So, if the rest of the speaker is handling ten watts, you need 100 watts for the bass alone. When you consider that these will be called on for peaks, that means even more power. Can your speakers handle that amount of power? Can it handle the cone excursion needed to move that much air at that frequency? I kinda doubt it.

Again, this is just an example. Real world considerations can get even more ugly.

Like another said, equalizers are best utilized to cut a frequency range, not boost it beyond all reason.

 

[KEW]

Without knowing xmax for ls50 bass driver, it is probably not possible to know if PEQ will work or not above the port frequency (50 hz). Below the port frequency PEQ may not be as effective but again depending on the xmax, PEQ may be somewhat effective.

I agree Xmax and heat are the biggest concerns. The surround doesn't look like it is made for the dramatic excursions you are interested in. It looks like a mid-woofer surround, not a subwoofer. KEF specs power at 25-100Watts, FWIW.

FWIW, Sound stage has NRC measurements of FR:

 

[shkumar4963]

Agree. But lets look at what kills a speaker. Mechanically I am assuming that high excision does not hurt as there are mechanical stops on both sides to stop diaphragm movement before it tears the surrounds. But what happens to the current and impedence of a speaker when the excursion is maxed out. Does it fry because of extreme low impedence and reaultant high current and lack of air cooling. Or current limitation circuit in the amp protects the speaker.

 

[BoredSysAdmin]

It's an interesting theoretical conversation, but back in real life I would rather get a small sub like HSU STF2 for $375 shipped rather than taking a chance of permanent damage to $1500 speakers.
First option would give you significantly better bass anyways, I guarantee you

 

[shkumar4963]

Agreed. My purpose was to better understand how speakers work and where are the limitations from many knowledgeable people here.