A Watt is a Watt or do you need a powerful amplifier for good bass?

[Audioagnostic]

The title says it all. There is an audio myth that large amplifiers are needed to get good bass.
Is this true?

My feeling as a scientifically inclined audio agnostic leans heavily towards the opinion that a Watt is a Watt and that therefore it does not make a difference what the power of your amplifier is, or how heavy the transformer in the amplifier is. My knowledge about audio is quite limited though hence my question in this forum.

Please let me know if there is a good source or thread on this subject. I searched but have difficulties to find a definitive answer.

I am of course aware that more power can give more output but my question is about sound levels that do not require a large amount of power.

My setup, if this helps.

I am using dynaudio excite x38 speakers, sensitivity 88 dB, 4 ohm, 34 Hz - 23 kHz.

At the moment I am powering it with a raspberry pi based streamer amplifier combo, hifiberry amp2. https://www.hifiberry.com/shop/boards/hifiberry-amp2/

I really like the tiny size and the combination sound excellent. Power is stated as 60 Watt but that seems highly optimistic. I have it limited in Volumio to avoid the distortion this amp will have at higher output levels.

Why ask this question if it sound good you might say. Well of course I like to experiment and will hook up a big amplifier that I have gathering dust in the attic. It will be impossible to do a blind test and I just want to know a bit more about the theoretical aspects of amplification and bass.

This was quite a long question, hope you guys can help me.

 

[watchnerd]

The title says it all. There is an audio myth that large amplifiers are needed to get good bass.
Is this true?

My feeling as a scientifically inclined audio agnostic leans heavily towards the opinion that a Watt is a Watt and that therefore it does not make a difference what the power of your amplifier is, or how heavy the transformer in the amplifier is. My knowledge about audio is quite limited though hence my question in this forum.

Please let me know if there is a good source or thread on this subject. I searched but have difficulties to find a definitive answer.

I am of course aware that more power can give more output but my question is about sound levels that do not require a large amount of power.

My setup, if this helps.

I am using dynaudio excite x38 speakers, sensitivity 88 dB, 4 ohm, 34 Hz - 23 kHz.

At the moment I am powering it with a raspberry pi based streamer amplifier combo, hifiberry amp2. https://www.hifiberry.com/shop/boards/hifiberry-amp2/

I really like the tiny size and the combination sound excellent. Power is stated as 60 Watt but that seems highly optimistic. I have it limited in Volumio to avoid the distortion this amp will have at higher output levels.

Why ask this question if it sound good you might say. Well of course I like to experiment and will hook up a big amplifier that I have gathering dust in the attic. It will be impossible to do a blind test and I just want to know a bit more about the theoretical aspects of amplification and bass.

This was quite a long question, hope you guys can help me.

I own, and have owned, a lot of Dynaudio speakers.

In the past, they were known to be power hungry / lower efficiency than the rated specs, especially the 'inside magnet', big voice coil designs. The newer, smaller VC, 'outside magnet' designs are more efficient.

But back to the general question:

Damping factor is usually what is cited as the 'it factor' when getting better bass, with better meaning tighter and more controlled.

Cheap amps don't tend to have good damping factor. Although you can get pretty good damping factor with mid-tier class D amps.

On the other hand, there is a diminishing return where the damping factor is 'enough' and more damping factor doesn't help.

 

[etc6849]

Welcome to the forum. You clearly have a technical background and are willing to learn which is great.

Maybe start by reading this interesting application note... It is definitely not true that a watt is a watt (measurements such as THD+N for low power levels will quickly show this).

https://benchmarkmedia.com/blogs/application_notes/power-amplifiers-the-importance-of-the-first-watt

This one discussing speaker sensitivity versus amplifier power is decent too.
https://benchmarkmedia.com/blogs/application_notes/speaker-efficiency-and-amplifier-power

I would recommend a bigger amplifier, but I'd want to see measurements of both amps (or at least basic specs) and the impedance curve of the speaker. Class D might be your cheapest, smallest and best bang for your buck option. However, they are not all going to measure and perform the same.

I would also look for the impedance curve of you speakers (impedance just means resistive and reactive load). This is going to change with frequency (since reactance does). Your speakers may honestly dip below 4 ohms for lower frequencies for all we know. If needed, I would call the manufacturer and ask for this information.

I would think of the amp as a voltage source, so as the impedance drops, the speakers are demanding more current from the amp. There are some DIY hypex ncore options I've seen that can handle this (or even prebuilt optoins like this: https://www.ati-amp.com/AT52XNC.php). Problem is they aren't $39 either... I only recommend the hypex ncore modules as I've seen Audio Precision measurements for them. I personally wouldn't buy any amp that I can't compare measurements for.

If I can't see THD at very low loads and at very high loads, I'm not interested. There was a THX Standards site that objectively compared amps, but it seems it is gone now?

 

[watchnerd]

I would also look for the impedance curve of you speakers (impedance just means resistive and reactive load). This is going to change with frequency (since reactance does). Your speakers may honestly dip below 4 ohms for lower frequencies for all we know. If needed, I would call the manufacturer and ask for this information.

Dynaudios used to have pretty punishing impedance in the lower frequencies.

The new designs aren't as bad, but I still wouldn't call them an easy load.

The OP's X38 hits a minimum of 3.3 ohms.

 

[etc6849]

Interesting. My Klipsch P-39f's (99dB @ 2.83V / 1m) have a nasty impedance dip too: https://www.stereophile.com/content/klipsch-palladium-p-39f-loudspeaker-measurements

This is probably why Klipsch recommends up to a 1000W amp despite the claimed sensitivity. Hopefully Amir has measured some mid-tier class d amps. I don't doubt there is a cheaper option than an ATI 52xNC line or a Benchmark AHB2 amp.

I ended up going all out and actively tri-amping my speakers, but it is a lot of learning and money, plus I was looking for ultimate performance.

Dynaudios used to have pretty punishing impedance in the lower frequencies.

The new designs aren't as bad, but I still wouldn't call them an easy load.

The OP's X38 hits a minimum of 3.3 ohms.

 

[FrantzM]

Hi

I would venture an explanation:

We are thinking anything under 150 Hz.. Arbitrary number but cannot be mistaken for anything else ..
To begin let us remove , just for now, the room. It plays an important, perhaps determinant role in the quality of bass produced. We are positing that we have an ideal room or better we're in free space. We are also supposing a pistonic driver. Your usual electromagnetic , round woofer driver.
Bass requires that an important volume of air be displaced. You also need it move linearlily,in other words, the displacement must remain linear i-e proportional to the signal, ideally exactly like the signal. For that to happen you need either a large diaphragm or a smaller diaphragme with a good travel. The ideal would be a large diaphragm with a good travel. Large means greater mass. The greater mass means more inertia , thus greater force to move it and stop it ... Greater force means greater power ... Smaller drivers are possible but there travel has to be much longer for the same volume of air displaced and they tend (have to ?) to also be less sensitive thus more power anyway ...
Very simplistic, I know we could delve in arcana but it seems to me to be the crux of the matter. You will not move large masses with a few watts.. You can but in the real world of bass drivers with their mass, low sensitivity and cabinet loading .. You need to send a few watts in a driver. Moreover you need the variations of impedance of the driver to not be seen by the amp ... Damping factor aka as low output impedance needs to be high.
In the end for bass the more powerful and the lower the output impedance ( to an extent .. Not sure , that a 1000 damping factor would be audible as compared to say 200 but ...) The better. There is much more to bass reproduction but ...

 

[solderdude]

Bass levels need about 10x more 'power' than the mids in this song (Keb Mo, the worst is yet to come)
So depending on how loud one plays the bass requires by far the most power.

When playing softly it does not matter if the amp is 10W or 1000W.
When playing at realistic or loud levels the 10W is coming up short, the 1000W is not.
As long as you don't hear any distortion your speakers will be fine with both a 10W or 1000W amp.

Consider the following. The difference between 40W and 60W is only 1.7dB.
To play about twice as loud you need 10x more power (10dB).
So if a 40W amp is a bit short you may want to look for something that can put out 200W or so and gain 7dB in max. loudness.
Or... buy an equally good sounding higher efficiency speaker.

 

[Audioagnostic]

Thanks watchnerd etc6849 and frantzM.

Of course it seems that my question is naive and the answer will be it depends on the characteristics of your speakers and your amplifier.
The world is not black and white but composed of many nuances...

The problem I am getting aware of seems to be that damping factors of amplifiers are not usually published? Yet I would appreciate a link as to what would be an acceptable combination of damping factor and speaker impedance. Do small class D amplifiers always have poor damping factors to drive speakers with low impedances?

 

[Audioagnostic]

Solderdude you seem to be of the opinion that high wattage is only required for higher sound levels? A Watt is a Watt? Or am I misinterpreting your post?

 

[solderdude]

When you would be listening at very low levels only (88dB/W) then yes... it really does not matter if the connected amp is 10W or 1000W.
For high efficiency speakers things are different as noise and distortion at low power levels may become problematic.

Basically... it depends on the efficiency of the speaker, how loud you want to play (without distortion/clipping) and how well the amp can handle the varying impedance.
A Watt is a Watt but a 20W tube amp is not the same as a 20W SS amp and a 20W amp in 8Ohm that is only 25W in 4 Ohm is not the same as a 20W amp in 8 Ohm that can provide 80W in 2Ohm as well.

A lot has been written about damping factors.. When speakers have passive filters there are always large inductors in series with the woofers. These have a DC resistance and also increase in impedance at higher bass frequencies... bye bye high number DF.
For midranges and tweeters, certainly in low efficiency designs the speakers are often attenuated a few dB with resistors... by bye DF.

Active speakers ... that's the way to go. Short wires no passive components in series... yes !
Dynaudio has them too (love these speakers .. but don't own them)

 

[watchnerd]

Dynaudio has them too (love these speakers .. but don't own them)

I have both Dynaudio actives (LYD series) and passives (Contour 20)

I probably do at least 60% of my listening on the active LYD speakers and they're very satisfying, especially for the money.

 

[RayDunzl]

My cheap subs experiment, the Cheezewoofers, are 15" with only an advertised 150W each. I haven't measured the voltage going to the drivers.

Since there are 4 of them, and they run in parallel with the 12" woofers in the mains, I get to reduce the amplitude of the individual bass drivers by 9dB vs a single woofer per side, and find the lowish power rating sufficient for the task. The house rattles excessively before the speakers sound strained.

I figured I might reduce the low frequency harmonic distortion by spreading the load, and stopped there, being currently satisfied with the result. I haven't spread them around the room yet, they're just stacked outboard of the mains.

Main amps rated for 700W @ 4 ohms.

 

[maty]

Some hours ago, in Audiocircle forums, I wrote about the need of watts with low sensitivity speakers.

https://www.audiocircle.com/index.php?topic=150792.msg1716836#msg1716836

-> https://www.soundstagehifi.com/index.php/system-one/1237-nads-d3045-a-d3020v2-on-steroids

New speakers from a new amp?​

​

Although the D 3045’s new feature set is significant, for me the biggest benefit is the power output from the D 3045’s class-D power-amp section. The change from 30Wpc to 60Wpc shouldn’t have amounted to a hill of beans -- no surprise to those who know that every doubling of power results in a volume increase of only 3dB from the speakers. That difference in SPL is only just noticeable, even if achieving it requires substantial upsizing of an amplifier’s power supply, output transistors, etc. Nonetheless, the differences I heard were dramatic -- far more than just being able to play music louder.​

​

The night before I unboxed the D 3045, the D 3020 V2 was still in my system, hooked up to the Paradigm Monitor SE Atom speakers ($300/pair) I wrote about in my first two columns. When fellow writer Philip Beaudette came over, wanting to hear the system he’d been reading about, I played him some tracks. He agreed that it sounded really good -- then said, “What more would most people ask for?”​

The next morning, I unboxed the D 3045, swapped out the D 3020 V2, and put on the same track. I got a jolt as if I’d been shocked with 500V. “Rockin’ in the Free World” now thundered with dynamics that simply hadn’t been there the day before. Chad Cromwell’s bass drum hit like a punch in the stomach, the entire audioband was reproduced with much more clarity -- and I could turn it up louder. It was as if I were hearing a different pair of speakers.​

 

[DonH56]

A Watt is a Watt but that is only one measure of performance. Bigger amps usually have more output devices and greater gain with greater feedback ratios that lead to lower output impedance. Lower output impedance means higher damping factor, FWIW. Lower output impedance means the amplifier is less influenced by the speaker's (often wildly) varying impedance.

Whether a doubling of power matters very much depends upon how loudly you listen and where you start from. Doubling from 1 W to 2 W may not be as big a deal as from 10 W to 20 W or whatever. A speaker that is 100 dB/W/m sensitive may not need a doubling from 50 W to 100 W (or whatever) whilst an 80 dB/W/m panel might. Generalizations are generally bad. And perception bias generally very strong, obscuring real results (good or bad).

 

[maty]

https://www.soundstage.com/index.ph...itor-se-atom-loudspeakers&catid=77&Itemid=153

83.9dB and about minimum 6 Ohms

 

[GGroch]

Whoa Guys. Lets look again at the specific products that Audioagnostic is using.

The description of the Hifiberry amp he links to says it is stereo and has 60 watts...but that is too general to know what is meant. The photo of the board shows a single TAS5756M Stereo Digital Amp chip. Texas Instruments Data Sheet shows Instantaneous WPC at 20 watts and Continuous WPC at 18 watts at 10% THD into 4 ohms. Yep, that is how these chip makers rate power output...10%

Audioagnostic's Speakers are 4 driver towers of medium efficiency.
In my old audio sales days I would ask where are they located, how big is the room, and how loud do you listen before trying to answer his question...but very few people use tower speakers on a desktop 2 feet away. (Audioagnostic is that how you use them?).

So, it is certainly true that if you listen at low levels all the time with content material lacking in deep bass (which takes more power as previously stated) you might be OK. But I doubt anyone here would choose an amp that perhaps puts out 12 WPC cleanly and has very little reserve dynamic power as optimal for these speakers.

How amps...particularly digital amp specs work today is new to me. I own an "80 WPC" FX Audio FX502Pro that was just tested by Amir to put out maybe 30. Which turns out to be fine because I am using it to push desktop monitors and I am old. But by almost any standard the Hifiberry does not seem optimum for these speakers.

Please let me know how I am mistaken.

 

[watchnerd]

Whoa Guys. Lets look again at the specific products that Audioagnostic is using.

The description of the Hifiberry amp he links to says it is stereo and has 60 watts...but that is too general to know what is meant. The photo of the board shows a single TAS5756M Stereo Digital Amp chip. Texas Instruments Data Sheet shows Instantaneous WPC at 20 watts and Continuous WPC at 18 watts at 10% THD into 4 ohms. Yep, that is how these chip makers rate power output...10%

Audioagnostic's Speakers are 4 driver towers of medium efficiency.
In my old audio sales days I would ask where are they located, how big is the room, and how loud do you listen before trying to answer his question...but very few people use tower speakers on a desktop 2 feet away. (Audioagnostic is that how you use them?).

So, it is certainly true that if you listen at low levels all the time with content material lacking in deep bass (which takes more power as previously stated) you might be OK. But I doubt anyone here would choose an amp that perhaps puts out 12 WPC cleanly and has very little reserve dynamic power as optimal for these speakers.

How amps...particularly digital amp specs work today is new to me. I own an "80 WPC" FX Audio FX502Pro that was just tested by Amir to put out maybe 30. Which turns out to be fine because I am using it to push desktop monitors and I am old. But by almost any standard the Hifiberry does not seem optimum for these speakers.

Please let me know how I am mistaken.

I don't think you're mistaken at all.

But I assumed he knew you can't really drive a 4 driver tower speaker that dips below 4 ohms off a Raspberry Pi chip board with no meaningful power supply (perhaps I'm wrong and the OP didn't know), and was just asking generally about how power and bass relate....

 

[SIY]

The unknown here is what the amp's max output is at different impedance magnitude and phase angles. The old Audio Critic amp reviews used the Power Cube, which really does a great job of telling you what happens with real-world loads (and the biggest impedance swings for non-pathological speakers is in the bass).

I get where people are coming from re: damping factor, but I think that (again putting aside pathological cases like zero feedback pentode amps or OTLs) it's a very secondary thing, especially when you compare it to all the other series resistances. If you do a sim of a speaker's bass response with a damping factor of 10 (i.e., 0.8 ohm source impedance) versus 1000 (i.e., 0.008 ohm source impedance), you'll rarely see the bass response change be anything even close to significant.

 

[watchnerd]

The unknown here is what the amp's max output is at different impedance magnitude and phase angles. The old Audio Critic amp reviews used the Power Cube, which really does a great job of telling you what happens with real-world loads (and the biggest impedance swings for non-pathological speakers is in the bass).

I get where people are coming from re: damping factor, but I think that (again putting aside pathological cases like zero feedback pentode amps or OTLs) it's a very secondary thing, especially when you compare it to all the other series resistances. If you do a sim of a speaker's bass response with a damping factor of 10 (i.e., 0.8 ohm source impedance) versus 1000 (i.e., 0.008 ohm source impedance), you'll rarely see the bass response change be anything even close to significant.

I wrote about damping factor not for this specific use case (which is all solid state), but as part of a general universe of amps, in which goofy things like OTLs do exist.

 

[Audioagnostic]

Thanks for all your input although I have to say that I am still very much confused!

That my current combination is not optimal is clear. I cannot reach higher sound levels because of the limited power. I am still unsure if listening at low levels will improve if I lug down my old creek evo amplifier from my attic and hook it up. Subjectively it probably will...

I probably should have stated my question differently. Is it likely there will be a difference in bass if you have different amplifiers outputting the same amount of power? This where one amplifier is a tiny hifiberry compared to a large hifi grade amplifier. Of course without a difference in distortion levels.

However, what I gather from all your answers is that this question is impossible to answer since it depends on characteristics of the speaker and amplifier. Is that a correct summary?