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

[Solipsistik]

3dB is EASILY discernible by the average player, even 1dB difference can be heard by many players. 7-9dB is a MONSTROUS difference.

I literally pulled that from a study on human hearing. The human ear will generally not be able ti discern a 3db difference. In other matters, you keep agreeing with me but arguing the opposite anyway.

Whatever. I know where this goes. You're also the guy who said that a 15" speaker is no different than a 10" speaker.

 

[Solipsistik]

• 4 ohms = sq rt (100/4) = 5A
• 8 ohms = sq rt (100/8) = ~3.54S

Here's what you guys are missing. Amps (current) are what gets things done. In real life components have different weights, different efficiencies and different friction coefficients to name a few - a higher current will always do more work in a given time, moderated by voltage. Amps matter. Don't believe me? Grab ahold of, say, 100V and a great deal less than one amp, and you'll likely live. Grab ahold of 1 amp at 50V and there's an excellent chance that you'll die. Current matters. Current makes a difference. 4 ohm speaker systems have a higher current than 8 ohm systems do. Think of amperes as the flow of water in a tube and Voltage as the pressure of that flow - at 4 ohms you have lower voltage and higher current (amperes) and so the speakers naturally do more work since there's much more current and the action of them is more precise because there's less pressure. AKA, they're more efficient.

Try a 120a battery in your diesel truck. Let me know if it starts. An 800a battery will start it. They're both 12V. Good luck.

 

[5StringBlues]

 

[agedhorse]

I literally pulled that from a study on human hearing. The human ear will generally not be able ti discern a 3db difference. In other matters, you keep agreeing with me but arguing the opposite anyway.

Whatever. I know where this goes. You're also the guy who said that a 15" speaker is no different than a 10" speaker.

No sir, the study you have chosen sounds like it was mined via AI, because the information is very much incorrect. As part of my day job, I do a LOT of controlled listening tests with different players when designing new amps and cabinets, and MY data shows that most players have no difficulty discerning 3dB differences in AB testing, and a surprising number can reliably hear 1dB differences (which I can too).

You must have taken my speaker size comment out of context, though it's possible for the TONE of a 15" and a 10" speaker to be the same IF that's the designer's intent and they are willing to give up some other performance parameter in the process (ie. trade-offs)

Here's what you guys are missing. Amps (current) are what gets things done. In real life components have different weights, different efficiencies and different friction coefficients to name a few - a higher current will always do more work in a given time, moderated by voltage. Amps matter. Don't believe me? Grab ahold of, say, 100V and a great deal less than one amp, and you'll likely live. Grab ahold of 1 amp at 50V and there's an excellent chance that you'll die. Current matters. Current makes a difference. 4 ohm speaker systems have a higher current than 8 ohm systems do. Think of amperes as the flow of water in a tube and Voltage as the pressure of that flow - at 4 ohms you have lower voltage and higher current (amperes) and so the speakers naturally do more work since there's much more current and the action of them is more precise because there's less pressure. AKA, they're more efficient.

Try a 120a battery in your diesel truck. Let me know if it starts. An 800a battery will start it. They're both 12V. Good luck.

You have simplified your explanation (and apparently your understanding of electronics) to the point that you are simply wrong.

There are several of us here who work with is stuff every day (I have been an electrical engineer for 45+ years), and while we have tried to explain it, you are not understanding even the most basic aspects.

First of all, current, voltage and power are all inter-related via OHM's law, there's no way to change one without the others changing.

For example, you give the example of grabbing hold of 1 amp at 50V, yet through the average body 50V is intrinsically safe, meaning that there is no way for 1 amp to flow because the body's internal resistance is too high. In fact, this is EXACTLY why voltage less than ~50 volts is NOT hazardous, and other than in medical implants, is exempt for most of the international safety standards. I have to know this (for real) because I am professionally responsible for representing products as they go through the UL process for all international safety standards, and that means practicing in front of UL's regulatory engineering review panel.

Current flows BECAUSE of voltage and resistance, that's what Wasnex was trying to explain, but you missed the basics.

In your speaker example, while the current through the coil is what generates the varying magnetic field, you are ignoring that the number of turns will be different (lower) in a 4 ohm speaker which offsets the increased current. This is part of the issue with making different impedance speakers with the same sensitivity.

Your truck example doesn't apply here, not even a little bit.

 

[Wasnex]

Here's what you guys are missing. Amps (current) are what gets things done. In real life components have different weights, different efficiencies and different friction coefficients to name a few - a higher current will always do more work in a given time, moderated by voltage. Amps matter. Don't believe me? Grab ahold of, say, 100V and a great deal less than one amp, and you'll likely live. Grab ahold of 1 amp at 50V and there's an excellent chance that you'll die. Current matters. Current makes a difference. 4 ohm speaker systems have a higher current than 8 ohm systems do. Think of amperes as the flow of water in a tube and Voltage as the pressure of that flow - at 4 ohms you have lower voltage and higher current (amperes) and so the speakers naturally do more work since there's much more current and the action of them is more precise because there's less pressure. AKA, they're more efficient.

Try a 120a battery in your diesel truck. Let me know if it starts. An 800a battery will start it. They're both 12V. Good luck.

Sorry but you are jumping to a lot of wrong conclusions .

 

[fdeck]

Here's why it's not simple. The driving force, that's proportional to current, is offset by multiple opposing forces: Electrical damping, mechanical damping, mechanical resistance (springy-ness), inductance, and inertia (mass). All of those things also affect the relationship between voltage and current (impedance).

To make it more fun, the properties of the speaker that govern these forces have to be balanced against one another to produce a speaker with an acceptable response curve, such as a reasonable amount of bass response with a minimal "hump" at the natural resonant frequency of the system. The efficiency that results from this balance is actually surprisingly low -- a few percent.

For things that can be described as real bass speakers, these factors have already been balanced in this way. This would include, for instance, 8- and 4-Ohm versions of otherwise similar speakers.

I don't want to pile on here, and I'm not implying any blame if this stuff isn't intuitive. There's a lot of physics and math behind it.

Which I'm happy to share.

 

[Guitalia]

This might be the first instance of AI guesswork being invoked to argue with TalkBass's resident professional amp design experts. Probably not the last.

 

[Dasgre0g]

 

[Bassdirty]

......average SPL sensitivity, between 50Hz and 5kHz at 1 watt RMS into the nominal impedance, calculated into a 1/2-space anechoic acoustic environment.

Yea, I was JUST gonna say this, but ya beat me to it.

Kidding, No Idea what language this even is.
Half kidding, I do get most of it. (Ok, some).





*** would I do without 'emojis"?

Carry on.

 

[pepj]

The amp might not think any differently but I had a 4 ohm and 8 ohm cabs of the same design and the 8 ohm sounder 'better'.
Small small difference but enough for me to notice and want the 8ohm back

 

[Kaplan]

If the speaker's impedance is halved (e.g., from 8 to 4 ohm), the damping factor is also halved when using the same amplifier. This means less control.

 

[Rich Fiscus]

You can learn a lot from this thread, and some of it is even true.

 

[agedhorse]

If the speaker's impedance is halved (e.g., from to ), the damping factor is also halved when using the same amplifier. This means less control.

While this is technically correct, on a (typical) solid state amp specifically, changing the damping factor from say 500 to 250 will have virtually zero effect on the control or frequency response.

Why is this? Because the speakers used for bass guitar (and also PA) use overhung voice coils, which meant that a good portion of the voice coil sits outside the magnetic gap. This resistive component of the load effectively decreases the damping factor, and is often modeled when designing speakers. This resistive component also decreases sensitivity, which is why there is the trade-off between large Xmax, sensitivity and high frequency extension.

 

[DuluthDank]

A little different since the drivers will not have exactly the same performance at 4 ohms and 8 ohms. They may be pretty close but in general the 4 ohm driver will have a little lower sensitivity compared with the 8 ohm version.

How would the end user perceive this slight loss in sensitivity, in terms of the words they would use to describe the difference?

 

[agedhorse]

How would the end user perceive this slight loss in sensitivity, in terms of the words they would use to describe the difference?

Lower maximum SPL.

 

[jnewmark]

The amp might not think any differently but I had a 4 ohm and 8 ohm cabs of the same design and the 8 ohm sounder 'better'.
Small small difference but enough for me to notice and want the 8ohm back

Funny, the opposite happened to me, but it might be brand/driver/cab specific. Although the difference in volume was not night and day, the tone or "girth" of the sound was very noticeable to me; the overall sound of the cab was thicker and a tad louder at 4 ohms. I have always used 4 ohm cabs since,(Schroeder).

 

[Kaplan]

Funny, the opposite happened to me, but it might be brand/driver/cab specific. Although the difference in volume was not night and day, the tone or "girth" of the sound was very noticeable to me; the overall sound of the cab was thicker and a tad louder at 4 ohms. I have always used 4 ohm cabs since,(Schroeder).

Lower control at 4 ohms (damping factor) results in “more bass.” According to agedhorse, this isn't audible, but in your case, it certainly is.

 

[jnewmark]

Lower control at 4 ohms (damping factor) results in “more bass.” According to agedhorse, this isn't audible, but in your case, it certainly is.

Yes, although I had others listen on a gig who thought the same, two were bass players. I had two Schroeder cabs, a single 115, one 8, one 4, and switched them during a break. Now, I'm not saying this was a strict blind testing method by any stretch, but it was a real gig situation, with no difference in settings on the amp. Obviously, a lot of other factors were in play like room conditions, amount of people coming and going in the room, yadda yadda. But, it was enough for me to start using 4 ohm cabs, at least with the Schroeders.

 

[agedhorse]

Lower control at 4 ohms (damping factor) results in “more bass.” According to agedhorse, this isn't audible, but in your case, it certainly is.

And it’s not true either (in general) but may be in some specific cases where the 4 ohm driver was optimized and the 8 ohm driver wasn’t as well designed for the application.

Yes, although I had others listen on a gig who thought the same, two were bass players. I had two Schroeder cabs, a single 115, one 8, one 4, and switched them during a break. Now, I'm not saying this was a strict blind testing method by any stretch, but it was a real gig situation, with no difference in settings on the amp. Obviously, a lot of other factors were in play like room conditions, amount of people coming and going in the room, yadda yadda. But, it was enough for me to start using 4 ohm cabs, at least with the Schroeders.

That may be the case with this specific cabinet/design, but it’s not be any means a universal truth. You are also driving the 4 ohm cabinet with a lot more power, this may benefit a particularly inefficient cabinet.

 

[Kaplan]

And it’s not true either (in general) but may be in some specific cases where the 4 ohm driver was optimized and the 8 ohm driver wasn’t as well designed for the application.

"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)