Trying to decide which subwoofer to get

[hispls 5,000+ posts]

Still moving 30 times per second, but it's seeing more peak power without more movement


I'm saying it's seeing more power without cooling more when it gets a square wave

So under this theory a square wave at 10hz below tuning would be safe while a sine wave at 50hz where it would be moving even less would be a problem?

 

[adulbrich 5,000+ posts]

So under this theory a square wave at 10hz below tuning would be safe while a sine wave at 50hz where it would be moving even less would be a problem?

No, because I'm guessing 10hz is below your box tuning and the sub would unload and exceed it's mechanical limits.

Rise would generally be lower at the lower frequency. If it was, which I'm not saying it would in all cases, the sub would see more power.

If it sees equal power and doesn't exceed mechanical limits, possibly.

 

[wew lad 5,000+ posts]

The proper tool for the job is Dayton DATS. 100$ at Parts Express and worth every penny. But yes, that's what you'd want to do to be safe.... assuming of course that the amp manufacturer didn't already gamble (cough Brazilians cough) that you'd run their rated impedance nominal sub and that within normal bandwidth you're not already coming in a bit high.
In the example I posted, if you could cross over with a steep enough slope you could probably get away with 24-64hz running this "2 ohm" woofer with a 4 ohm stable amp. It may go into protect though even at low power when it sees the lower impedance though. If you were using test tones you could be 100% confident of what's going to happen or if you mixed your own music or had a good spectrum analyzer you could chose songs that didn't have anything outside the "safe" areas and be fine as well.

good insight, thanks. you wouldn't trust a DMM and clamp meter to give an accurate representation of the actual impedence im seeing? I ask because I'm getting a dual .7 sub and I have a 1 ohm hd3000, obviously running this amp at .4 would be a dumb idea, but .7 maybe not if i can verify that my rise is greater than 1.5 from 20-80hz

I'll probably end up getting a 2k @.5 amp if i do decide to run at .4

 

[Massive spl]

good insight, thanks. you wouldn't trust a DMM and clamp meter to give an accurate representation of the actual impedence im seeing? I ask because I'm getting a dual .7 sub and I have a 1 ohm hd3000, obviously running this amp at .4 would be a dumb idea, but .7 maybe not if i can verify that my rise is greater than 1.5 from 20-80hz
I'll probably end up getting a 2k @.5 amp if i do decide to run at .4

If u have a dual .7 woofer u can run at .35ohm or 1.4ohm... But yea I'd get diff amp and run at .35ohm

 

[wew lad 5,000+ posts]

If u have a dual .7 woofer u can run at .35ohm or 1.4ohm... But yea I'd get diff amp and run at .35ohm

i have two of them, if i decided to get a new box id run them at .7 once i knew my rise

just for one though ya i need a new amp or i can run this at 1.4

 

[hispls 5,000+ posts]

good insight, thanks. you wouldn't trust a DMM and clamp meter to give an accurate representation of the actual impedence im seeing? I ask because I'm getting a dual .7 sub and I have a 1 ohm hd3000, obviously running this amp at .4 would be a dumb idea, but .7 maybe not if i can verify that my rise is greater than 1.5 from 20-80hz
I'll probably end up getting a 2k @.5 amp if i do decide to run at .4

You MUST test at each frequency from 15hz up to 100hz anyway to be 100% safe... really by 80hz you should see a steady upward trend of ANY subwoofer due to inductance of the coil which will guarantee a steady rise of impedance as you go higher and higher so once you see that trend you can extrapolate from there. . Even if your crossover is set at 80hz for example it's still playing 120hz it's just attenuated. And as you can see from the example it varies pretty wildly right in the range where 90% of music is going to be playing.

I'd bet that a .7 DCR sub would NEVER be below 1 ohm within that bandwidth but you really can't know for certain until you measure and FYI 1 ohm is still really hard on semiconductors.

No, because I'm guessing 10hz is below your box tuning and the sub would unload and exceed it's mechanical limits.
Rise would generally be lower at the lower frequency. If it was, which I'm not saying it would in all cases, the sub would see more power.

If it sees equal power and doesn't exceed mechanical limits, possibly.

Did you even look at the impedance data I posted? 32hz was 4.5 ohms and 24hz was 10 ohms, your claim that "rise" is less at lower frequency just proves that you have no idea how a loudspeaker system works and that you're not even paying attention but are merely arguing for the sake of raising your post count. Besides which if were talking about power it implies P=IE so "rise" doesn't enter into it.

Your "less cone movement" theory falls on it's face when you examine what the woofer does through its entire bandwidth.

Does "clean" power effect the mechanical limits? If not why did you bring that up?

 

[adulbrich 5,000+ posts]

You MUST test at each frequency from 15hz up to 100hz anyway to be 100% safe... really by 80hz you should see a steady upward trend of ANY subwoofer due to inductance of the coil which will guarantee a steady rise of impedance as you go higher and higher so once you see that trend you can extrapolate from there. . Even if your crossover is set at 80hz for example it's still playing 120hz it's just attenuated. And as you can see from the example it varies pretty wildly right in the range where 90% of music is going to be playing.
I'd bet that a .7 DCR sub would NEVER be below 1 ohm within that bandwidth but you really can't know for certain until you measure and FYI 1 ohm is still really hard on semiconductors.

Did you even look at the impedance data I posted? 32hz was 4.5 ohms and 24hz was 10 ohms, your claim that "rise" is less at lower frequency just proves that you have no idea how a loudspeaker system works and that you're not even paying attention but are merely arguing for the sake of raising your post count. Besides which if were talking about power it implies P=IE so "rise" doesn't enter into it.

Your "less cone movement" theory falls on it's face when you examine what the woofer does through its entire bandwidth.

Does "clean" power effect the mechanical limits? If not why did you bring that up?

No, I didn't even look at it. I didn't say it was always lower at lower frequencies. If I did, I mis-spoke

Clean power affects thermal more than mechanical

 

[hispls 5,000+ posts]

No, I didn't even look at it. I didn't say it was always lower at lower frequencies. If I did, I mis-spoke
Clean power affects thermal more than mechanical

Still sticking with the "clean" power statement though, huh? What happens when you're listening to music where the instrument is played through a tube over-drive to intentionally clip the signal? And playing a clipped signal below tuning is fine so long as the cone is moving more than at other points?

Go back and look at the impedance data I posted (ignore phase). Let the implications sink in of what would happen over a long enough time period playing a wide enough variety of music. Consider also, changes to the box would move those numbers all around as would different subs. I wish I had saved more impedance data but that old laptop that I ran the WT3 on got so messy with the software I was using for work that I generally lost all my date a couple times a year.

Have you looked at a waveform on graph paper sinusoidal vs. square to understand what AC "Power" is? I'm shocked that you don't touch on this in just high school physics class? Can you take any basic electronics theory classes in your school? Drawing the waveform and shading in the part which represents "power" is like a week 1 exercise and very illustrative.

I will agree that cone movement comes into play with cooling. I've observed that larger subs tend to overheat faster than smaller subs (motor, suspension and coil being equal) but it's not dramatic enough to substantiate a "clean" power theory where the difference in excursion between a 12 and 18" driver will be far more dramatic than the 30% you claim is the deal breaker with "dirty" power. Why are not larger subs in the same product line rated for less power?

I would theorize that "clipping" is simply a boogeyman used to explain thermal failures from too much power and that the shape of the waveform of that power isn't terribly relevant. I think people also greatly underestimate how quickly heat builds up into a runaway situation as you approach and especially when you exceed the thermal limits of the coil and that's a big part of this.

 

[adulbrich 5,000+ posts]

Still sticking with the "clean" power statement though, huh? What happens when you're listening to music where the instrument is played through a tube over-drive to intentionally clip the signal? And playing a clipped signal below tuning is fine so long as the cone is moving more than at other points?
Go back and look at the impedance data I posted (ignore phase). Let the implications sink in of what would happen over a long enough time period playing a wide enough variety of music. Consider also, changes to the box would move those numbers all around as would different subs. I wish I had saved more impedance data but that old laptop that I ran the WT3 on got so messy with the software I was using for work that I generally lost all my date a couple times a year.

Have you looked at a waveform on graph paper sinusoidal vs. square to understand what AC "Power" is? I'm shocked that you don't touch on this in just high school physics class? Can you take any basic electronics theory classes in your school? Drawing the waveform and shading in the part which represents "power" is like a week 1 exercise and very illustrative.

I will agree that cone movement comes into play with cooling. I've observed that larger subs tend to overheat faster than smaller subs (motor, suspension and coil being equal) but it's not dramatic enough to substantiate a "clean" power theory where the difference in excursion between a 12 and 18" driver will be far more dramatic than the 30% you claim is the deal breaker with "dirty" power. Why are not larger subs in the same product line rated for less power?

I would theorize that "clipping" is simply a boogeyman used to explain thermal failures from too much power and that the shape of the waveform of that power isn't terribly relevant. I think people also greatly underestimate how quickly heat builds up into a runaway situation as you approach and especially when you exceed the thermal limits of the coil and that's a big part of this.

I know some music has intentional clipping to get a different sound. Old rock has a lot of clipping. I know newer stuff does too. No I'm not saying clipping below tuning is ok.

We don't do electrical stuff in physics class. Lots of velocity stuff with radial motion and falling objects right now

If 30% isn't significant, what would you say is?

If clipping "isn't terribly relevant", why not just max your gains and wang?

My Z's were fine up until the clipping light started to flicker on the 20k. A couple times I could smell a hint of glue, so I turned it down. Because I mounted the amp where I could see it while driving, I was able to monitor it easily. It was especially easy to see at night. I always played it safe for daily listening. Only went a click or two into soft clipping for demos. I know the clipping indicator on amps isn't 100% accurate, but it's better than nothing

 

[hispls 5,000+ posts]

I know some music has intentional clipping to get a different sound. Old rock has a lot of clipping. I know newer stuff does too. No I'm not saying clipping below tuning is ok.
We don't do electrical stuff in physics class. Lots of velocity stuff with radial motion and falling objects right now

If 30% isn't significant, what would you say is?

If clipping "isn't terribly relevant", why not just max your gains and wang?

My Z's were fine up until the clipping light started to flicker on the 20k. A couple times I could smell a hint of glue, so I turned it down. Because I mounted the amp where I could see it while driving, I was able to monitor it easily. It was especially easy to see at night. I always played it safe for daily listening. Only went a click or two into soft clipping for demos. I know the clipping indicator on amps isn't 100% accurate, but it's better than nothing

The point is that too much power is too much power regardless of the shape of the waveform!

Since most people try to "match" their amp to their subs or even run amps capable of doubling rated power to their amps the extra 30% power whether clipped or unclipped puts you from a safe operating condition into trouble really fast. The logarithmic dB scale and the way acoustic power works makes this even more of an issue.

Let's say your volume is at 22 on your head unit and you can bang away all day long, your amp is making 5000W. Now raise that one click on the volume knob and you're making 7500W. Your coils that were right at their limit at 2400W each are now way beyond that. Now raise volume knob another click and the amp is trying to make 10KW.... make that a clipped waveform and it's making 12-13KW. Even forget about the volume knob and substitute the wide dynamic range of music. The same example with you playing a 1000W amp and I'd wager it would be virtually impossible to blow those Z's even with a full square wave. My 0-35 Kenwood is right about 1 click = 1.4dB and once you get higher and higher compression ensures even less than that actual output for the power you're trying to throw into things so essentially in the space between what feels like just slightly louder you go from perfectly safe to get ready for smoke.

Clipping is far more strenuous on the amp and sounds like dirt is why we avoid it. From the sub's point of view, current creates heat and too much is too much. Again, take a 12" sub next to an 18" sub same motor and suspension and correctly proportioned box/port and tuning and play a 30hz tone and watch how far the cone moves. I'd be willing to bet it's more than 30% difference which your theory suggests is the deal breaker with "dirty" power.

Does your "clip" indicator light sense voltage, current, or a product of both? It's highly unlikely it's actually examining the waveform and is likely just going by some theoretical "max" voltage.

So, back to OP's post, he has a 800W sub that he is throwing 1300W into assuming he's hard clipping his 1000W amp. I'm very confident a nice round looking 1300W sine wave would fry that Alpine sub just as quickly.

 

[adulbrich 5,000+ posts]

The point is that too much power is too much power regardless of the shape of the waveform!
Since most people try to "match" their amp to their subs or even run amps capable of doubling rated power to their amps the extra 30% power whether clipped or unclipped puts you from a safe operating condition into trouble really fast. The logarithmic dB scale and the way acoustic power works makes this even more of an issue.

Let's say your volume is at 22 on your head unit and you can bang away all day long, your amp is making 5000W. Now raise that one click on the volume knob and you're making 7500W. Your coils that were right at their limit at 2400W each are now way beyond that. Now raise volume knob another click and the amp is trying to make 10KW.... make that a clipped waveform and it's making 12-13KW. Even forget about the volume knob and substitute the wide dynamic range of music. The same example with you playing a 1000W amp and I'd wager it would be virtually impossible to blow those Z's even with a full square wave. My 0-35 Kenwood is right about 1 click = 1.4dB and once you get higher and higher compression ensures even less than that actual output for the power you're trying to throw into things so essentially in the space between what feels like just slightly louder you go from perfectly safe to get ready for smoke.

Clipping is far more strenuous on the amp and sounds like dirt is why we avoid it. From the sub's point of view, current creates heat and too much is too much. Again, take a 12" sub next to an 18" sub same motor and suspension and correctly proportioned box/port and tuning and play a 30hz tone and watch how far the cone moves. I'd be willing to bet it's more than 30% difference which your theory suggests is the deal breaker with "dirty" power.

Does your "clip" indicator light sense voltage, current, or a product of both? It's highly unlikely it's actually examining the waveform and is likely just going by some theoretical "max" voltage.

So, back to OP's post, he has a 800W sub that he is throwing 1300W into assuming he's hard clipping his 1000W amp. I'm very confident a nice round looking 1300W sine wave would fry that Alpine sub just as quickly.

So you're saying the shape of the waveform doesn't mater? I disagree about that, but we're obviously not getting anywhere.

Does one click on the volume knob really make that much difference as far as power goes?

Not sure what the 20k's clip indicator uses

 

[bullshit8421]

I don't plan on competing with it i just like to feel my bass as I'm driving. And i had a newer version of the type r's and the amp was only at half power because i was still breaking the sub in so it was only sending the sub about 500 watts at 2 ohms. Some of you mentioned Sundown's how do those compare to the others I've listed. I couldn't find much on them and I've spent months looking

 

[adulbrich 5,000+ posts]

Tons of Sundown info on the forums. Lots of nutthuggers too.

 

[hispls 5,000+ posts]

So you're saying the shape of the waveform doesn't mater? I disagree about that, but we're obviously not getting anywhere.
Does one click on the volume knob really make that much difference as far as power goes?

Not sure what the 20k's clip indicator uses

You can not believe in gravity but it will effect you and until you can disprove modern physics you're in the minority.

Read about it here.

https://www.ibiblio.org/kuphaldt/electricCircuits/AC/AC_1.html

Like I said, I've measured 1.4dB per click on my Kenwood. Assuming NO COMPRESSION (which is unlikely) that's almost doubling power every two clicks. If you have a 1-50 volume dial yours may be 1dB per click but that's still a LOT Of extra power as you really start winding up. Sounding "twice as loud" requires 10X more power, so yes, power increase as you click up towards max volume is dramatic.

I don't plan on competing with it i just like to feel my bass as I'm driving. And i had a newer version of the type r's and the amp was only at half power because i was still breaking the sub in so it was only sending the sub about 500 watts at 2 ohms. Some of you mentioned Sundown's how do those compare to the others I've listed. I couldn't find much on them and I've spent months looking

How did you figure out that you're only getting "half power" out of your amp?

 

[adulbrich 5,000+ posts]

You can not believe in gravity but it will effect you and until you can disprove modern physics you're in the minority.

Read about it here.

https://www.ibiblio.org/kuphaldt/electricCircuits/AC/AC_1.html

Like I said, I've measured 1.4dB per click on my Kenwood. Assuming NO COMPRESSION (which is unlikely) that's almost doubling power every two clicks. If you have a 1-50 volume dial yours may be 1dB per click but that's still a LOT Of extra power as you really start winding up. Sounding "twice as loud" requires 10X more power, so yes, power increase as you click up towards max volume is dramatic.

How did you figure out that you're only getting "half power" out of your amp?

Mine goes up to 35