Consequences of speaker EQing on amp power needed

[daftcombo]

Hi,

Let's say I have a braodband speaker with a sensitivity of 90dB/W/m.
If I apply some EQ, for instance a room curve or any other bass boost (like +10dB at 40Hz descendint to 0dB at 20kHz):
- does it "change" the speaker sensitivity?
- how much SPL will I have at 1 meter with 1 Watt?
- do I need a more powerful amp?

Cheers.

 

[andreasmaaan]

If you boost the output by 10dB at 40Hz, that will require 10x the power in comparison to the rest of the spectrum.

It doesn’t “change” the sensitivity of the speaker, but it would require more power to reach the same broadband SPLs.

Usually, though, EQ is best used to cut a bit of energy out at room modal frequencies, not to apply boost. It depends on your goals though of course.

 

[DonH56]

Speaker sensitivity does not change for all practical purposes. (There is power compression as you approach the power limits but that can be neglected for this.)

Speaker sensitivity is normally specified as a single point at 1 kHz. Other than that, you have to get more data from the manufacturer or measure it yourself. The SPL at the listening position depends upon the power into the speaker, its sensitivity, how far away you are sitting, and what sort of room you are in (large, small, treated or not -- fundamentally how much reflected energy is present at the listening position). An online SPL calculator can provide some insight though are generally only useful a rough guide since so many factors are not included. Here's one: Peak SPL Calculator

+10 dB requires 10x the power. Whether you need a more powerful amp depends upon how loudly you want to listen, the speakers, etc. -- all the factors above. The scale is logarithmic: P(dB) = 10*log10(Pout/Pref). If you set the reference to 1 then you can start playing with the power ratios:

​

+3 dB = 2x the power​

+6 dB = 4x the power​

+10 dB = 10x the power​

In general a 1 dB change is barely noticeable, 3 dB is "a little bit louder", and 10 dB is twice as loud. That is in the midrange; at low frequencies the equal-loudness curves compress so 3~5 dB may sound (feel) twice as loud. See e.g. https://en.wikipedia.org/wiki/Equal-loudness_contour

HTH - Don

 

[Cortes]

savyy guys, a practical question:

1. I listen to ~50 db average (my head is about ~1.4m distance from the monitors)
2. My office is small (3.1x3.9x2.67 m^3)
3. Monitors sensibility is 86db
4. Integrated Amp is a valve Class A @ 20 W.

Volume knob of integrated amp uses to be at ~1/8 of the full range (my new SMSL-SU8 DAC generates a huge output)

Am I missing anything with this integrated amp?. Apart from lower distorsion, am I missing something that super-powered Hypex modules can give me?.

 

[DonH56]

Using the calculator I linked you should achieve ~99 dB from a pair of them driven by 20 W each assuming no room reinforcement. I'd guess you are fine.

 

[daftcombo]

I listen to ~50 db average

This seems very low, just above the noise floor of any room. Are you sure of this value?

 

[Cortes]

This seems very low, just above the noise floor of any room. Are you sure of this value?

yes, it's fine, measured. Usually in the 45-55 range. Reasons are two: I'm almost always with music on, continous loud levels are unhealthy; and it's on office, with people nearby I don't want to bother. I have good headphones (Sr-007+srm727), but I only like heaphones during short periods.

 

[DonH56]

A quiet room is often in the 30~40 dB SPL range, with a good studio in the 10~20 dB range.

 

[daftcombo]

Ok. At that volume, I think there will be no need for higher-end products than your 20W amp. Distortion at 0.1% is sufficient.

 

[svart-hvitt]

If you boost the output by 10dB at 40Hz, that will require 10x the power in comparison to the rest of the spectrum.

It doesn’t “change” the sensitivity of the speaker, but it would require more power to reach the same broadband SPLs.

Usually, though, EQ is best used to cut a bit of energy out at room modal frequencies, not to apply boost. It depends on your goals though of course.

If you «cut a bit of energy» by means of EQ (say DSP room compensation), does it mean that the headroom of your system takes a cut too?

If so, never underestimate the headroom in your system and better have a margin of safety?

 

[andreasmaaan]

If you «cut a bit of energy» by means of EQ (say DSP room compensation), does it mean that the headroom of your system takes a cut too?

If so, never underestimate the headroom in your system and better have a margin of safety?

I agree it's always better to have extra headroom, but can't see how cutting a bit of energy by means of EQ could reduce headroom?

 

[Cortes]

Ok. At that volume, I think there will be no need for higher-end products than your 20W amp. Distortion at 0.1% is sufficient.[/QUOTE]

it's what I suspected... so the thing to get better sound is either, (i) upgrade to active (Gelenece 8340/ Dynaudio Core 7 / Similar), (ii) purchase a better passive monitor (it's shame Revel are almost impossible in Europe), or (iii) simply to buy a small subwoofer like the Rel Tzero to get a more 'corporal' experience.

 

[svart-hvitt]

I agree it's always better to have extra headroom, but can't see how cutting a bit of energy by means of EQ could reduce headroom?

Thinking through this once more, I am not so sure myself either...

I think I was confused, like this:

Imagine the extreme, theoretical case where you EQ down the curve by 30 dB. Then you’d need a volume knob that goes to say 130 to compensate for the cutting off of energy. So your system plays at a lower SPL after EQ than before. But distortion will not/cannot be a result of the EQ if you play at an equal, very high SPL compared to prior to EQ...

Did you understand my confusion....?

 

[andreasmaaan]

Thinking through this once more, I am not so sure myself either...

I think I was confused, like this:

Imagine the extreme, theoretical case where you EQ down the curve by 30 dB. Then you’d need a volume knob that goes to say 130 to compensate for the cutting off of energy. So your system plays at a lower SPL after EQ than before. But distortion will not/cannot be a result of the EQ if you play at an equal, very high SPL compared to prior to EQ...

Did you understand my confusion....?

Yeh I think so What I would have said is that boosting a particular frequency will tend to reduce headroom, but cutting a particular frequency will not.

 

[Ron Texas]

Yeh I think so What I would have said is that boosting a particular frequency will tend to reduce headroom, but cutting a particular frequency will not.

This is very important, especially with small stand mounts. They don't have a lot of headroom to start with.

 

[daftcombo]

it's what I suspected... so the thing to get better sound is either, (i) upgrade to active (Gelenece 8340/ Dynaudio Core 7 / Similar), (ii) purchase a better passive monitor (it's shame Revel are almost impossible in Europe), or (iii) simply to buy a small subwoofer like the Rel Tzero to get a more 'corporal' experience.

IMHO, for 50 dB listening, it is not worth investing in anything if your speakers are already decent.
"Better speakers" could have a larger bandwidth or less distortion, but at that volume you won't hear much low frequencies (because of human ear various thresholds following the frequencies) nor distortion under 0.3 %.

 

[DonH56]

IMHO, for 50 dB listening, it is not worth investing in anything if your speakers are already decent.
"Better speakers" could have a larger bandwidth or less distortion, but at that volume you won't hear much low frequencies (because of human ear various thresholds following the frequencies) nor distortion under 0.3 dB.

And if you are trying to keep the level low in an office a subwoofer is a bad idea... Sound isolation in offices is usually pretty poor, especially at low frequencies.

 

[LTig]

savyy guys, a practical question:

1. I listen to ~50 db average (my head is about ~1.4m distance from the monitors)
2. My office is small (3.1x3.9x2.67 m^3)
3. Monitors sensibility is 86db
4. Integrated Amp is a valve Class A @ 20 W.

Volume knob of integrated amp uses to be at ~1/8 of the full range (my new SMSL-SU8 DAC generates a huge output)

Am I missing anything with this integrated amp?. Apart from lower distorsion, am I missing something that super-powered Hypex modules can give me?.

The position of the volume knob has no relevant meaning. But with 50 db average level the peak levels are in the 70-75 dB region. To reach this level you need less than 1 W peak power, so there is nothing to gain from amps with more power.

 

[LTig]

it's what I suspected... so the thing to get better sound is either, (i) upgrade to active (Gelenece 8340/ Dynaudio Core 7 / Similar), (ii) purchase a better passive monitor (it's shame Revel are almost impossible in Europe), or (iii) simply to buy a small subwoofer like the Rel Tzero to get a more 'corporal' experience.

Take also the Neumann KH 80 DSP in account. It's very small but the reviews here and here are very good, at low levels matching or exceeding the Neumann KH 310. Using EQ for loudness correction should be no problem at 50 db level.

 

[Cortes]

The position of the volume knob has no relevant meaning. But with 50 db average level the peak levels are in the 70-75 dB region. To reach this level you need less than 1 W peak power, so there is nothing to gain from amps with more power.

amazing, you nailed it!. Indeed I can run direct the speakers from the DAC.

However, somehow I thought that more power is good for higher dynamic range. Infact, I don't understand why headphones amps are so bulky, when so little power is needed.