2-ohm vs. 4-ohm midbass speakers

[Ge0]

No cons, but no pros necessarily either. "More power going in" isn't any advantage if the speaker can't use it... and if your speaker needs more power (especially in a free-air setup like a door), that's not necessarily a good speaker. I'd have lots of questions about it, and why I couldn't drive it to full output on the 4 ohm level of power. Of course, that also assumes we're talking about an otherwise-identical comparison - a 4 ohm speaker that left you wanting, so you bought the 2 ohm version... which doesn't really exist in the midbass world. My point is - "more power" has no intrinsic benefit.
You want the appropriate amount of power to drive the speaker to full excursion.
And if that's possible with, say, 50 watts at 4 ohms, why would you swap in a speaker that required 100 watts to do the same thing?

Same things with subwoofers - I hear people bragging all the time about how a sub can handle over 1000w - "that's impressive!"
No, it's not really. It's a big, fat, heavy high-mass winding that's increasing moving mass to the point where it NEEDS nearly 1000w just to get loud. If you could get the same excursion and output with a sub that only needs 200w - THAT's the more impressive subwoofer.

(just like I wonder all the time, how so many people today are totally OK with thinking they need a 2000w+ amplifier, upgraded alternator, extra batteries, etc... just to drive a couple subs - and apparently aren't bottoming them out! Tell me THAT doesn't raise questions about the most inefficient system ever... )

All that matters is what matters - that you are driving your speakers cleanly, and are getting full output out of them - that your amp (at whatever impedance) can drive them to full excursion. People focus on the stuff that doesn't matter - or worse, praise the stuff they don't understand (triple-stack magnet, anyone?) - a whole lot.

And I don't mean you, this is a great question to actually start a deep-dive into some real understanding.

OEM's drop speaker loads down to 2 ohm due to the latest ultra cheap micro-amp configurations. For the rest of us with SQ amps designed for the 4 ohm world --> Holy shit! What an epiphany. Congrats and thanks .

Just to reiterate geolemon's point: https://www.youtube.com/watch?v=GHFwb69T-Tc

Ge0

[jtrosky]

Ok, so stupid question. After changing my midbass speakers from 4-ohm speakers to 2-ohm speakers, I'm assuming that I should reset gains on the amp for those channels?

Thanks.

[JCsAudio]

Ok, so stupid question. After changing my midbass speakers from 4-ohm speakers to 2-ohm speakers, I'm assuming that I should reset gains on the amp for those channels?

Thanks.

Bust out your microphone and REW and just adjust the gain so that your mid-bass speakers are playing matched up to your target curve relative to the other drivers and subwoofer.

[jtrosky]

Bust out your microphone and REW and just adjust the gain so that your mid-bass speakers are playing matched up to your target curve relative to the other drivers and subwoofer.

Thanks for the reply - I appreciate it. My concern wasn't really about the level of the speakers in relation to the other speakers at this point. My concern was whether or not the switch from 4-ohm speakers to 2-ohm speakers would require me to adjust the gains on the amp, in regards to amp and speaker "safety". I can easily account for the level differences from within the DSP itself.

After I posted the question, I did check the JL documentation and their documentation lists completely different voltages for setting gains with a multimeter, depending on whether the speaker is 2 ohms or 4 ohms. Since the speakers aren't even connected during this gain-setting procedure, it sounds like they want the gains to be set significantly lower for channels that will be connected to 2-ohm speakers.

With all of that said, what I find interesting is that the 2-ohm speakers really don't seem to provide any more "volume" than the 4-ohm speakers that they replaced - so I don't think lowering the gains per the JL documentation really makes sense.

So, I guess I'll just leave everything as-is. :-) I was really hoping to get more volume from the 2-ohm CDT speakers, but that doesn't seem to be the case - which seems strange to me. Not only are they 2-ohm speakers, but the sensitivity on them is also higher - so you'd think that there would be a noticeable level difference....

Is there any way to tell for sure whether the speakers I received are *really* 2-ohm speakers or not? Unfortunately, nothing on the speaker itself actually identifies the speaker - there is just a "generic" CDT label. No model number, no ohm rating and no serial number... Kind of crappy that they aren't identified on the actual speaker at all. For all I know, I actually received 4-ohm speakers in a box that has a 2-ohm "sticker"...

[geolemon]

Yes - just meter it with your DMM set to Ohms.
You are just measuring the straight DC resistance, if you will - but it'll be somewhere between 3 and 4 ohms if it's a 4 ohm speaker (usually closer to three).
And similarly a 2 ohm speaker should measure somewhere pretty close to 2 ohms.

[JCsAudio]

Thanks for the reply - I appreciate it. My concern wasn't really about the level of the speakers in relation to the other speakers at this point. My concern was whether or not the switch from 4-ohm speakers to 2-ohm speakers would require me to adjust the gains on the amp, in regards to amp and speaker "safety". I can easily account for the level differences from within the DSP itself.

After I posted the question, I did check the JL documentation and their documentation lists completely different voltages for setting gains with a multimeter, depending on whether the speaker is 2 ohms or 4 ohms. Since the speakers aren't even connected during this gain-setting procedure, it sounds like they want the gains to be set significantly lower for channels that will be connected to 2-ohm speakers.

With all of that said, what I find interesting is that the 2-ohm speakers really don't seem to provide any more "volume" than the 4-ohm speakers that they replaced - so I don't think lowering the gains per the JL documentation really makes sense.

So, I guess I'll just leave everything as-is. :-) I was really hoping to get more volume from the 2-ohm CDT speakers, but that doesn't seem to be the case - which seems strange to me. Not only are they 2-ohm speakers, but the sensitivity on them is also higher - so you'd think that there would be a noticeable level difference....

Is there any way to tell for sure whether the speakers I received are *really* 2-ohm speakers or not? Unfortunately, nothing on the speaker itself actually identifies the speaker - there is just a "generic" CDT label. No model number, no ohm rating and no serial number... Kind of crappy that they aren't identified on the actual speaker at all. For all I know, I actually received 4-ohm speakers in a box that has a 2-ohm "sticker"...

I’ll tell you what, point me in the right direction to the speakers ts parameters and I’ll model the 2 ohm vs 4 ohm so we can compare in Bassbox pro. This should give us a good estimate on the maximum SPL you’ll be able to generate on any given power and I’ll be able to verify excursion too which could be a limiting factor overall.

[Jdunk54nl]

After I posted the question, I did check the JL documentation and their documentation lists completely different voltages for setting gains with a multimeter, depending on whether the speaker is 2 ohms or 4 ohms. Since the speakers aren't even connected during this gain-setting procedure, it sounds like they want the gains to be set significantly lower for channels that will be connected to 2-ohm speakers.

With all of that said, what I find interesting is that the 2-ohm speakers really don't seem to provide any more "volume" than the 4-ohm speakers that they replaced - so I don't think lowering the gains per the JL documentation really makes sense.

2 ohms offers less resistance then 4ohms so you get more current. Power=V*I . So with more current (I) the voltage (V) needs to drop to get the same power.

For your jl xd600/6 amp

To get 75w on 4 ohms, you'd need 17.32 volts and 4.33 amps to get (75w= 17.32v x 4.33 amps)
To get 100w on 2 ohms, you'd need 14.14 volts and 7.07 amps. (100w = 14.14v x 7.07 amps)

Moral of the story, if you keep your voltage at 17.32 volts and don't adjust, you are now sending 17.32 volts and 8.66 amps to your speakers or 150 watts of power. Your amp (on paper) can't handle that, you are heavily clipping the signal.

Granted, that all assumes you are actually sending all that power to it.

Also, as to why the speakers don't seem much louder, Humans require about 10db gain to be perceive double volume. Doubling power is only a 3db gain (if you go from 4ohms to 2ohms amps somewhat double), so even if you got a 5db gain by higher sensitivity and doubling the power, you still wouldn't perceive that to be much louder.

[jtrosky]

2 ohms offers less resistance then 4ohms so you get more current. Power=V*I . So with more current (I) the voltage (V) needs to drop to get the same power.

For your jl xd600/6 amp

To get 75w on 4 ohms, you'd need 17.32 volts and 4.33 amps to get (75w= 17.32v x 4.33 amps)
To get 100w on 2 ohms, you'd need 14.14 volts and 7.07 amps. (100w = 14.14v x 7.07 amps)

Moral of the story, if you keep your voltage at 17.32 volts and don't adjust, you are now sending 17.32 volts and 8.66 amps to your speakers or 150 watts of power. Your amp (on paper) can't handle that, you are heavily clipping the signal.

Granted, that all assumes you are actually sending all that power to it.

Also, as to why the speakers don't seem much louder, Humans require about 10db gain to be perceive double volume. Doubling power is only a 3db gain (if you go from 4ohms to 2ohms amps somewhat double), so even if you got a 5db gain by higher sensitivity and doubling the power, you still wouldn't perceive that to be much louder.

Yeah, this whole 2-ohm speaker "upgrade" was kind of disappointing. I wasn't expecting anywhere near a "doubling" of volume, but I *was* expecting to at least hear and see a very minor increase in output from the 2-ohm speakers, but I'm not seeing *any* increase - not a single dB - either via measurements or just using my ears. The volume level is basically the same as it was with my 4-ohm speaker that had a lower sensitivity rating. Once I lower the amp gain, I'm assuming my actual output level will be *lower* than my previous 4-ohm speaker - which is why I'm kind of curious if they actually sent me 4-ohm versions of the speaker - or their whole "we have 2-ohm and 4-ohm versions of these speakers" is a bunch of BS. The speakers aren't labeled at all - either way, so I really have no idea what I have. The speakers actually sound good - no complaints there, but I'm not get any advantage - and maybe even a "downgrade" with the 2-ohm speakers. Oh well, at least I didn't pay much for them. :-)

The speakers are installed, so I can't easily check resistance with a multimeter - although, that doesn't always show the nominal impedance anyway from my experience.

[geolemon]

There's just too many variables.

I know I mentioned pages back that I am forehead-slapping all the time, seeing kids running 3000w 1 ohm amps/subs that have massive, heavy windings and concrete suspensions that make it so you NEED 3000w just to hear it...

Jtrotsky makes a good point on power and dB and psychoacoustics... and when you mix in a 4 ohm speaker that might be slightly more efficient than a 2 ohm speaker - you could easily waste that extra power that the speaker is getting.
To me, that makes it pointless.

For a subwoofer, I'd rather be the guy making his car "breathe" with a 400w amp, than be the guy with his headlights dimming and half as loud as mine.

For interior speakers, I'd definitely be hoping for at least a little more midbass. I feel you there.

[jtrosky]

Is there any chance that I just need to give the new 2-ohm speakers a little more "break-in" time before I experience the full output from them? I haven't taken new measurements yet, but after playing them at decent levels for a few hours yesterday while driving, they actually *do* seem to be a bit louder now - to the point where I feel that I need to reduce the midbass levels a little (haven't done it yet, but probably will). So maybe I was just too quick to "judge" them?

I think I will lower the gains on the amp for these channels, per JL - and see how things go. I don't want to risk damaging anything if I turn the system up too loud - especially since I actually felt the need to reduce the midbass level a little now anyway. I'm kind of curious what kind of level difference I'll see when I lower the gains per JL's recommendations (measured levels).