Does the same wattage sound different at 4 vs 8 ohms?

[agedhorse]

"When a tube amplifier has less control over a bass driver—typically due to a low damping factor—the result is a "looser," warmer, and more resonant bass sound rather than the tight, punchy sound associated with solid-state amps." (Google AI on bass response, lower damping)

I don't need to be educated by Google/AI anything on this topic, this is what I do professionally.

First of all, I was referring specifically to high damping factor solid state amps, per my comments answering other questions on this topic, and second, the difference in damping factor of a TUBE AMP between 4 and 8 ohms is almost nothing because the output impedance changes along with the change in output transformer tap. At 4 ohms, the output impedance falls by ~1/2, therefore the damping factor remains constant across impedances. It's a unique aspect of tube amps with output matching transformers.

On a tube amp versus solid state amp (which hadn't been mentioned prior to this comment), it's true that the damping factor it TYPICALLY (not always) lower on a tube amp. But this has nothing to do with the previous discussion about 4 ohm versus 8 ohm (single driver) speakers .

 

[Kaplan]

I don't need to be educated by Google/AI anything on this topic, this is what I do professionally.

First of all, I was referring specifically to high damping factor solid state amps, per my comments answering other questions on this topic, and second, the difference in damping factor of a TUBE AMP between 4 and 8 ohms is almost nothing because the output impedance changes along with the change in output transformer tap. At 4 ohms, the output impedance falls by ~1/2, therefore the damping factor remains constant across impedances. It's a unique aspect of tube amps with output matching transformers.

On a tube amp versus solid state amp (which hadn't been mentioned prior to this comment), it's true that the damping factor it TYPICALLY (not always) lower on a tube amp. But this has nothing to do with the previous discussion about 4 ohm versus 8 ohm (single driver) speakers .

Sorry, I didn't mean to lecture you. AI is just summarizing general knowledge. In my view, it's relevant to the topic, because I'm also familiar with the phenomenon where less bass control seems to produce more bass – though this is an illusion, since the bass simply becomes less precise. Whether this is noticeable in a specific case is another matter, but the OP asked about it.

 

[agedhorse]

Sorry, I didn't mean to lecture you. AI is just summarizing general knowledge. In my view, it's relevant to the topic, because I'm also familiar with the phenomenon where less bass control seems to produce more bass – though this is an illusion, since the bass simply becomes less precise. Whether this is noticeable in a specific case is another matter, but the OP asked about it.

There can be a perception of greater bass with some amps, damping factor can have some impact on this but it’s also due to amp voicing as well as the speakers themselves.

The problem with generalizations is that they are often inaccurate, and AI tends to enhance these inaccuracies because it trains on inaccurate data. This is especially true where urban myths factor into discussions.

 

[dbsfgyd1]

But how would it sound when you whip up the following scenario:

Solid state amp, obviously 4 ohm capable. You hook up one cabinet with 8 ohm, and set the dials so that on your test tone, exactly 100W arrive at the cabinet input.

Then, you modify the setup by hooking up a second, identical 8 ohm cabinet, but this is acoustically completely isolated from your listening spot, and yet again, you set the dials that exactly 100W arrive at the cabinet input.

Despite the fact that you are doubling the amount of speakers and the wattage of your amp, do not expect doubling your volume. You will have to ask the engineers here to explain the physics. I’m not qualified.

Personally, I don’t care for 4 ohm cabs as they are harder to match output wattage and the RMS rating of the cabs, and really can get problematic with multiple cabs set ups. From a more practical standpoint, there isn’t a major gain in decibles between a 4 ohm cab powered with the max output of an amp, compared with the same amp powering an 8 ohm version of the same cab at half the output wattage.

 

[Solipsistik]

Despite the fact that you are doubling the amount of speakers and the wattage of your amp, do not expect doubling your volume. You will have to ask the engineers here to explain the physics. I’m not qualified.

3db is roughly doubling the volume. It's just that your ear doesn't really make that out as "louder." Studies have been done showing that volume is not perceived in a linear way by the human ear.

 

[agedhorse]

3db is roughly doubling the volume. It's just that your ear doesn't really make that out as "louder." Studies have been done showing that volume is not perceived in a linear way by the human ear.

No, 3dB is a doubling of POWER, but this doesn't translate to the perception of doubling the volume. My experience is somewhere around 10dB translated to that impression with most players.

3dB is a clearly audible difference to most players, but not a doubling difference.

[edit} Wait a minute, didn't you say that a 3dB difference couldn't be heard in post #21???

 

[Solipsistik]

No, 3dB is a doubling of POWER, but this doesn't translate to the perception of doubling the volume. My experience is somewhere around 10dB translated to that impression with most players.

It's a doubling of sound intensity level (SIL), measured in decibels. "A decibel (dB) is a logarithmic unit used to measure sound levels, power ratios, and other quantities. It expresses the ratio between two values, typically power or intensity, on a logarithmic scale."

I use this scale a whole lot in the rural wireless infrastructure I've built. One end transmitting a particular amount of power expressed in dbm does not necessarily translate to it being received at the other end as "volume" or "signal level," because there are things in its way, including the atmosphere itself. Measured reception depends on many things including the distance from the source, etc. Measured differences in DB are accurate because it's determined at the exact point where you are receiving the signal (sound or otherwise), and thus is the sum of how much sound intensity you are receiving, not what it took to get it there.

3dB is a clearly audible difference to most players, but not a doubling difference.

However, measurement of 3db is still doubling. 9db would be an eight-fold difference.

[edit} Wait a minute, didn't you say that a 3dB difference couldn't be heard in post #21???

Yes, your ear won't make out 3db as being significantly louder. It takes 7-9db for the ear to hear a substantial difference in sound volume. This is down to the physics of your ear and your perception of amounts.

If you're doubling the cabs (double the sound amount of generated sound, see?), then you can often reach to your higher sound goal with less stress on the speakers, or simply attain a higher sound level, period. Otherwise, it's unlikely that anybody would bother with multiple cabs, at least not all aimed in the same direction. It isn't waves of transmitted power traveling to your ear like wireless signals, and in fact the electrical power that drives the speakers moves at roughly the speed of light, no; what is reaching your ears is vibrations of the atmosphere itself which move tiny fine hairs in the ear canal to detect those vibrations. No atmosphere, no sound waves. More speakers move more air... which stimulates more movement in your ear's components. It's also why different sized speakers with the same ratings have their own sound characteristics unique to them, they may move that air in wider or narrower frequencies and ampitudes.

It's moderately confusing, I grant you that. The biggest reason is that db is a logarithmic scale. I come from a time and place in the world where we taught both the pascal and db.

 

[agedhorse]

It's not confusing in the slightest. I deal with this math every day as an EE.

You say that a 3dB increase can't really be heard yet you also say that it's a doubling of volume, which is a perception. I say that a 3dB increase in volume can be easily heard by most players, and a 10dB increase is perceived by most players as a "doubling of volume".

You are missing the entire perception thing as it relates to volume, which is separate from voltage, power and SPL measurements and absolutes.

 

[el murdoque]

Despite the fact that you are doubling the amount of speakers and the wattage of your amp, do not expect doubling your volume. You will have to ask the engineers here to explain the physics. I’m not qualified.

Personally, I don’t care for 4 ohm cabs as they are harder to match output wattage and the RMS rating of the cabs, and really can get problematic with multiple cabs set ups. From a more practical standpoint, there isn’t a major gain in decibles between a 4 ohm cab powered with the max output of an amp, compared with the same amp powering an 8 ohm version of the same cab at half the output wattage.

I want to point to the line where I wrote that the second cabinet is acoustically completely isolated from the listening spot.
By that I meant complete isolation. In another room, or shielded by a magic, sound absorbing bubble.

 

[dbsfgyd1]

I want to point to the line where I wrote that the second cabinet is acoustically completely isolated from the listening spot.
By that I meant complete isolation. In another room, or shielded by a magic, sound absorbing bubble.

Most of us here are more about practical application as opposed.to experiments in physics. My response was directed at the mass. -.

 

[Solipsistik]

You say that a 3dB increase can't really be heard yet you also say that it's a doubling of volume, which is a perception. I say that a 3dB increase in volume can be easily heard by most players, and a 10dB increase is perceived by most players as a "doubling of volume".

I'm not saying it, the study said it. I haven't done a peer-reviewed study on human hearing, have you?

I do know that I don't own any piece of sound equipment that changes in any substantial way with a 3db adjustment. Can I hear it? Maybe I can, maybe I can't, a lot of that depends on the existing sound intensity and where I'm physically at in relationship to other objects that might dampen or reflect sound waves at a certain physical amount of "sound pressure," and that does matter there's an element of air particle impact (excited, moving air particles). A measurement will discern none of those variables but will give you the actual intensity of the sound and any differences you initiate at that fixed point.

I'm not missing perceived volume vs. power into the system at all. I'm talking measured sound intensity at a fixed position having changed by 3db. This even takes into account atmospheric differences etc. because the measurement is absolute, not constrained by human hearing or perception, not even by objects in the way of the transmitting speakers. The sound might distorted and muddy, or bright and harsh, but the sound measuring device won't even notice, (unless that's also one of its functions), since its duty is to report the intensity of the sound waves in decibels.

 

[agedhorse]

I conduct controlled, blind listening tests as part of my day job developing amps and speakers. I know without ANY doubt that a 3dB change in level is easily heard by most players. I have no problem at all perceiving a 3dB change in volume or SPL, and can detect 1dB changes pretty easily too (but I am trained to listen and my hearing, when tested, was well above average for a male of my age.

Since hearing is in part perception, perception plays a role in what players perceive in terms of volume. Perception is also different between men and women, both in absolute volume and in different frequency ranges.

 

[tom-g]

I'm not saying it, the study said it. I haven't done a peer-reviewed study on human hearing, have you?

I do know that I don't own any piece of sound equipment that changes in any substantial way with a 3db adjustment. Can I hear it? Maybe I can, maybe I can't, a lot of that depends on the existing sound intensity and where I'm physically at in relationship to other objects that might dampen or reflect sound waves at a certain physical amount of "sound pressure," and that does matter there's an element of air particle impact (excited, moving air particles). A measurement will discern none of those variables but will give you the actual intensity of the sound and any differences you initiate at that fixed point.

I'm not missing perceived volume vs. power into the system at all. I'm talking measured sound intensity at a fixed position having changed by 3db. This even takes into account atmospheric differences etc. because the measurement is absolute, not constrained by human hearing or perception, not even by objects in the way of the transmitting speakers. The sound might distorted and muddy, or bright and harsh, but the sound measuring device won't even notice, (unless that's also one of its functions), since its duty is to report the intensity of the sound waves in decibels.

I suggest to look up the definition of the units you are referencing to make more sense of what @agedhorse is talking about, i.e. volume in acoustics.

 

[KidAmnesia]

This is fun.

 

[Bassdirty]

This is fun.

T$

 

[agedhorse]

This is fun.

Not really

 

[Jazzdogg]

Not really

Why is it that the less some folks know, the louder they talk, the more fact-resistant they seem to be, and the more argumentative they become when confronted by experts using facts?

 

[tom-g]

Why is it that the less some folks know, the louder they talk, the more fact-resistant they seem to be, and the more argumentative they become when confronted by experts using facts?

It isn’t “the less some folks know“, it‘s they think they know how things work and not being able to admit they got it wrong. I have a brother who‘s a physicist. He knows everything.

 

[Jazzdogg]

It isn’t “the less some folks know“, it‘s they think they know how things work and not being able to admit they got it wrong. I have a brother who‘s a physicist. He knows everything.

Perhaps it's both...

 

[Jazzdogg]

Ego Is The Enemy, a book by Ryan Holiday, is worth reading.