[newzooreview]

If you run the numbers, a 20 watt amp that is stable down to 3Ω should be more than sufficient to drive perfect bass reproduction in a passive Spatial Audio loudspeaker, the X4 or M3 Sapphire for example. This assumes you are sitting 8 feet from the speakers, they are 93 dB efficient, and they are far enough from room boundaries to minimize issues (e.g, see below).

However, people report getting better bass (in some way or another) with high power amps with their Sapphires or X4s. I am curious about technical insights regarding why this might be.

I use a 25 watt per channel Class A amp with my Sapphires and have very good bass texture and volume where it exists in the recording. My Benchmark AHB2 amp did not provide (in the same room with same components) the tone and texture in the bass and the last half octave of bass that I get from my Pass Labs XA25. So my very limited experience suggests that the 20 watt theoretical calculation is about right and that component quality and amp design are more important than wattage above 20 watts.

Nevertheless, I've seen folks who heard improvements to bass moving to higher wattage amps in cases where the quality of parts and design of the amp was not significantly different.

Is there any technical wisdom out there that might shed light on these questions?



https://myhometheater.homestead.com/splcalculator.html

[Bingenito]

Your calc is correct and in a large room I only drove a Pass X250.8 out of class A twice and it was just to see how loud it would be. Needless to say the answer was too loud.

Few observations
1- Seems like you are happy with your current amp so why not stay there? Clearly this is the sound you prefer and this is all preference not right or wrong.
2- My move from Pass to high power class D was to get tighter bass and control the woofers with an iron fist. The do that so it met my expectations and preference.
3- All depends what music you listen to. If it is acoustic bass, slower and more romantic I can see you favoring Amp A vs Amp B. If you listen to any electronic music the differences in bass control are quite clear and not related to the power of the amp.

[catluck]

NewZoo - wondering how the calculator you reference deals with frequency differences or is that question meaningless? Isn't it true that lower frequencies require higher current to produce any given SPL (than mid/upper frequencies)?  Don't know how the calculator deals with the issue. But unless the many reviewers, and here I'll reference Orchard's site, are delusional or biased, there are too many reports of increased/enhanced bass, clarity, etc. (attributed to design? power output? circuit execution?).  I thought that with the 92dB M3's power above my 50 watt class A 845's would be superfluous, i.e., no discernable sonic difference.  That is clearly not the case.   Again, amp design? execution? I lack the engineering experience or education to comment let alone conclude.  But that the "more powerful" amps brought something new and highly desirable to the party (even if slight trade-offs say in harmonic bloom or spatial presentation) is, for me, no longer subject to dispute.  Seems like something is going on here.

[newzooreview]

I only drove a Pass X250.8 out of class A twice and it was just to see how loud it would be. Needless to say the answer was too loud.

Few observations
2- My move from Pass to high power class D was to get tighter bass and control the woofers with an iron fist. The do that so it met my expectations and preference.

This is what I'm interested to understand. Nothing aimed at anyone in particular, but the underlying reasons (physics, electrical engineering) for your observations are what puzzle me.

To stick with this example, the Pass 250.8 is biased to 25 watts Class A, and running it past Class A is not something that would be comfortable with the Spatials. So the Pass had far more power than was needed to achieve volume and control the low and mid drivers in a passive Spatial design. So it can't be the actual power (wattage) of the Class D amp that made a difference.

Yet, to generalize the case, I often see people say "I got a higher power amp and the bass improved."

With all of the volume generated by the first couple of watts, is the benefit of a 200 watt versus a 20 watt amp the speed of acceleration and deceleration in the higher powered amp? Does the extra power allow the high-powered amp to vary the voltage it is delivering to the woofer within, say, 100 nanoseconds while the 20 watt amp takes 300 nanoseconds? Would the ability to change current quickly then provide more punch (percussive force) and texture to bass compared to the slight smearing of the lower powered amp?

Shouldn't this be something that can be measured? I am not a measurement zealot, but it seems like there should be a way to gauge something like voltage delivery (knowing the impedances involved, the mass of the driver, etc.).

[Early B.]

This is what I'm interested to understand. Nothing aimed at anyone in particular, but the underlying reasons (physics, electrical engineering) for your observations are what puzzle me.

To stick with this example, the Pass 250.8 is biased to 25 watts Class A, and running it past Class A is not something that would be comfortable with the Spatials. So the Pass had far more power than was needed to achieve volume and control the low and mid drivers in a passive Spatial design. So it can't be the actual power (wattage) of the Class D amp that made a difference.

Yet, to generalize the case, I often see people say "I got a higher power amp and the bass improved."

With all of the volume generated by the first couple of watts, is the benefit of a 200 watt versus a 20 watt amp the speed of acceleration and deceleration in the higher powered amp? Does the extra power allow the high-powered amp to vary the voltage it is delivering to the woofer within, say, 100 nanoseconds while the 20 watt amp takes 300 nanoseconds? Would the ability to change current quickly then provide more punch (percussive force) and texture to bass compared to the slight smearing of the lower powered amp?

Shouldn't this be something that can be measured? I am not a measurement zealot, but it seems like there should be a way to gauge something like voltage delivery (knowing the impedances involved, the mass of the driver, etc.).

Good luck trying to figure out how to measure the relationship between power and sound or bass quality. I agree that power matters, but watts are only one measure of power and not a good one. There are plenty of low-fi amps with lots of watts or voltage.

[Bingenito]

Power supply and dampening factor are 2 places to look. Assuming manufactures publish real specs but that is another thread.

[Early B.]

Power supply and dampening factor are 2 places to look. Assuming manufactures publish real specs but that is another thread.

Power supply parts quality is a significant factor, but that's not measurable.   

[newzooreview]

Power supply and dampening factor are 2 places to look. Assuming manufactures publish real specs but that is another thread.

Damping factor doesn't predictably equate to bass performance, unfortunately. Too low a damping factor could produce audible problems but above the 200-400 range (theoretically) there's little audible difference due to damping factor. Nelson Pass has said that anything 20 or above is fine, but perhaps he measures it differently than Benchmark. The Benchmark AHB2 is 350 at 20Hz and the Pass Labs XA25 is 500 at no specified frequency. In my system with the Sapphires the XA25 had more bass texture, better tone, and reached lower.

The AHB2 has a maximum current output of 29 Amps peak per channel; the XA25 is nearly three times lower at 10 Amps peak per channel.

https://benchmarkmedia.com/blogs/application_notes/audio-myth-damping-factor-isnt-much-of-a-factor

I expect that Early B. is correct, and I have not missed any technical insights or new discoveries in the last few decades that I've been into good sound. It's a shame that NASA doesn't need a great stereo for the next moon mission. The investment in research regarding what measurements actually correlate to great sound just isn't there.

[Bingenito]

Instead of spending a lot of time reading online since much of it is half truths and marketing… why not invite a few people over who have different amps?

[Early B.]

Instead of spending a lot of time reading online since much of it is half truths and marketing… why not invite a few people over who have different amps?

You're being kind by using the term, "half truths." Ninety-eight percent of what is written about audio is nonsense, especially the technical stuff. You can only rely on your own experiences. Swapping gear with peers appears appealing.

[Bingenito]

You're being kind by using the term, "half truths.

Trying not to be another know it all... the internet has enough of those . That said, yes most of the marketing and specs are skewed. At the end of the day it is how things sound and only one way to figure that out.

PS If anyone can read the flowery articles that are called reviews and make any logical sense out of what they are saying then please enlighten me. Audio reviews remind me of some people in corp America who can talk for 20 mins and not say a damn thing. It is a real art or total waste depending on your perspective 

[Early B.]

Audio reviews remind me of some people in corp America who can talk for 20 mins and not say a damn thing. It is a real art or total waste depending on your perspective 

In grad school, the professor taught us to never respond to a question with, "I don't know," so we practiced talking without saying anything. It's silly, but that's corporate culture in America. All audio reviews should be limited to three sentences. Everything else is BS.   

[DaveWin88]

Damping factor doesn't predictably equate to bass performance, unfortunately. Too low a damping factor could produce audible problems but above the 200-400 range (theoretically) there's little audible difference due to damping factor. Nelson Pass has said that anything 20 or above is fine, but perhaps he measures it differently than Benchmark. The Benchmark AHB2 is 350 at 20Hz and the Pass Labs XA25 is 500 at no specified frequency. In my system with the Sapphires the XA25 had more bass texture, better tone, and reached lower.

The AHB2 has a maximum current output of 29 Amps peak per channel; the XA25 is nearly three times lower at 10 Amps peak per channel.

https://benchmarkmedia.com/blogs/application_notes/audio-myth-damping-factor-isnt-much-of-a-factor

I expect that Early B. is correct, and I have not missed any technical insights or new discoveries in the last few decades that I've been into good sound. It's a shame that NASA doesn't need a great stereo for the next moon mission. The investment in research regarding what measurements actually correlate to great sound just isn't there.

Damping factor can be a questionable topic. Some of the big guns say 50-100 is plenty. Hegel claims up to 4000 on some amps.