Why won't my 2000w sub amp power a 1000w max peak car sub?

Austin Berry

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Sep 17, 2013
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***UPDATED 2:30 PM 12/23/13*** (If you have already read the article, just look for the stars to view updated information)

[Blue colored words are responses to responders so all new coming people may be caught up on important information without going through all the comments]

I recently had a 15" 1500w Technical Pro sub woofer that I powered with a Gemini-2000w sub woofer amplifier. Recently the sub has gone out and even though I know how to re-cone a speaker, it will definitely cost more to re-cone this speaker than the speaker is worth.

Instead, what I would like to do is to buy a 15" sub woofer and install it in the previous box. I host movie nights and enjoy recreating sound as it is in movie theaters.

Here is where my trouble really comes in... I would like to replace the blown sub with a car sub, which usually carries more power than a HT sub, but comes with the problems of not being able to hit lower frequencies outside of a pressurized cabin, such as a car. I have been told that it will not sound as good as a home theater sub in a home.

My first question is, WHY? How is the design different from a HT sub.
My second question, will i really be able to hear a difference between a 15" 2000w car sub compared to a 15" 1500w HT sub?

My final question leads into this final story. I have a acquaintance who let me try my HT amplifier on his car audio sub woofers. I am not entirely sure of the specs but do know his car amp is no more than 1000 watts. His subs can rattle my ears pretty good. When I tried my HT Gemini-2000w sub amp on those same speakers, the speakers acted as though they were not receiving enough power from my amp. The sounds were quiet and sounded terrible. ***I have messed with different variations of ohm amount. For example, I tried to bridge the speaker for more power but had the same poor sounding effect. Not sure what the ground/lift switch does.***

So, my third and final question is, why wouldn't my amp power his car subs? This all leads into me buying a car sub for a replacement to my blown sub. Am I going to have trouble using a car sub as a replacement for my HT sub woofer?

If you can think of any reasons my amp would not correctly power his car subs, please let me know. Also feel free to ask any questions that were not clarified clearly within the post.

Thank you all and have a Merry Christmas!

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I think I know what you are saying itzdanielp. The HT sub was an 8 ohm sub-woofer while I believe the others were not less than 4 ohm speakers. I have an analog multimeter but when I try to measure the sub, I get no resistance or infinity ohms. I have tried measuring the resistance on a different speaker but still get infinity ohms. Not sure why, and I have the multimeter set to ohms 10 ohms. How would I tell if my amplifier only supports so many ohms?
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The exact model of my amp is Gemini XGA-2000

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I am not using a Low Pass Filter with my current setup. I have the signal from my main amp's sub woofer output plugged into the sub amp. Now, when you say stay away from 2 ohms, why is that? Isn't the less resistance the sub has, the louder it can perform at? I am trying to grasp the arts of the sound world but it can be difficult so please forgive me for any lame questions. Also thanks for the quick replies.
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So, if I had an AMP that could support 2 ohm, then I could run 2, 4, and 8 ohm speakers with it?
Also, how do you measure the hz the AMP is generating and the speaker. As said before, I could not calculate the ohms my previous speaker supported for some reason.
Finally, do you think that this speaker, Lanzar MAXP154D Max Pro 15-Inch 2000-Watt Small-Enclosure Dual 4-Ohm Subwoofer, or something along those lines would work completely normal with my AMP?
Also, once again, will there be any major drop in sound performance using a speaker such as these?

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Final question before closing the post. Firstly, thank you itzdanielp for all your help. As a college student at ITT Tech majoring in Electrical Engineering, it is always great to get a head start in some classes and helps to hear people clarify certain aspects of things we haven't learned yet. So once again, thank you for all your help

Now for my final questions, could my AMP burn out the previously described sub if wired incorrectly? For example, I wired the speaker to both stereo channels on my AMP instead of bridged the connection. Or if I wire the setup to hook both channels to the bridge on the AMP? Do I need to worry about burning this speaker out with the current AMP I posses?

Will sound quality be reduced being used as a HT sub? (The sub is 15")

And Finally, how loud do you think this speaker will sound in a home environment?
 

Antimatter79

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Jul 24, 2009
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Austin, you always run the risk of damaging your equipment if wired incorrectly. You may want to take a little time to fully understand bridging amp channels, series, and parallel wiring of speakers, multiple voice coils, etc. so that you can apply the advice you're given to variable situations. That way, even if you're asking a very specific question about a wiring configuration, you can take the knowledge and apply it to different scenarios, b/c no doubt you are wanting to experiment and try different things. The only choice you have at the moment with that sub and your amp is to wire it stereo which is not ideal.
1 - I would not feed a stereo signal to a subwoofer. Stereo is typically used to create depth and spaciousness of sound, as well as other effects, so the full low frequency range may/may not be fed identically to each channel. Stick to mono for your application.
2- As for burning your speaker out vs damaging your amp, there are lots of variables in play. Are you over driving the equipment, meaning are your amp or sub being driven to the point of distortion or clipping? Is your amp getting sufficient cooling? Those are things that will damage your equipment, aside from improper wiring. As for your amp not sounding good in your friend's car, unfortunately, your amp does not put out anywhere near 1000 watts; it's closer to 95 watts RMS per channel, not sure in bridge mode, most likely just 190 watts. If your friend's subs are truly designed to handle the power you stated (RMS, not max) then they probably have a very low sensitivity as well and your amp would not be enough to push them very loudly without distorting.
3 - The sub will be ok (not ideal b/c it will be in stereo) with your amp but do not set your crossover anywhere near 120 HZ. I didn't see any mention of your main speakers and what they're low end frequency response is, but you generally don't want to run your sub above 80Hz give or take; too much higher bass frequency will cause make your sub bass easily localized instead of seeming to come "from everywhere". Also, the narrower the frequency range for a subwoofer, the cleaner it can play. Also, that subwoofer is advertised as requiring a small enclosure, but that depends on what frequency you want to tune your box to. A car has the benefit of cabin gain; your home will not. It also won't have the same low bass notes in the house as it does in the car with the same enclosure, so you also have to account for that. Download the PDF manual from the website, find an online speaker cabinet calculator, and key in the speaker's measurements. This will give you an expectation of the correct enclosure size for your chosen tuned frequency, whether you go with a sealed or ported enclosure.
 

itzdanielp

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Aug 23, 2011
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More than likely it has to do with the impedance on the car sub vs the home theatre sub (probably 8ohm vs 4ohm).

Check your AMP, and see what the output at different impedance is.
 

Austin Berry

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I think I know what you are saying itzdanielp. The HT sub was an 8 ohm sub-woofer while I believe the others were not less than 4 ohm speakers. I have an analog multimeter but when I try to measure the sub, I get no resistance or infinity ohms. I have tried measuring the resistance on a different speaker but still get infinity ohms. Not sure why, and I have the multimeter set to ohms 10 ohms. How would I tell if my amplifier only supports so many ohms?
 

itzdanielp

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Aug 23, 2011
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Do you have any kind of LPF (Low Pass Filter) that you are using in conjunction with it? I ask because a good way to blow a cone is pumping higher frequencies at a higher power into a LFE.

The AMP is rate at Stereo 8ohms 90RMS, Stereo 4ohms at 125RMS, and Bridged 8ohms(what you would probably use) at 250RMS

So, depending on the impedance of the LFE you are using, would possibly explain the difference in volume.

If you wanted to use a car sub, you should be ok using a 4 or 8 ohm LFE, I would stay away from 2ohm, as you may overdrive it. 8ohm would be the preference. I would also put a lowpass filter at around 100-120Hz just to make sure you aren't overdriving it. And depending on the sub, put a highpass filter around 20-40hz (the amp can drive at as low as 10hz, which will destroy a sub not designed for frequencies that low)
 

Austin Berry

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Sep 17, 2013
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I am not using a Low Pass Filter with my current setup. I have the signal from my main amp's sub woofer output plugged into the sub amp. Now, when you say stay away from 2 ohms, why is that? Isn't the less resistance the sub has, the louder it can perform at? I am trying to grasp the arts of the sound world but it can be difficult so please forgive me for any lame questions. Also thanks for the quick replies.
 

itzdanielp

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Aug 23, 2011
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Using lower impedance speakers than your amp is designed to drive can cause your amp to overheat, and possibly be damaged (normally they will just shut off) this is because the speaker isn't giving enough resistance back to the amp, causing the amp to basically generate too much power.

Since you are driving a single LFE, it would be best to use a 8ohm sub with designed around 250RMS. And bridge both amp channels to the one output. Or you could use a cabinet with 2 4ohm or 8ohm subs each driven by a separate channel on the amp.

Verify the settings on your main amp to make sure it is cutting off the signal to the sub amp at around 120hz max.
 

Austin Berry

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So, if I had an AMP that could support 2 ohm, then I could run 2, 4, and 8 ohm speakers with it?
Also, how do you measure the hz the AMP is generating and the speaker. As said before, I could not calculate the ohms my previous speaker supported for some reason.
Finally, do you think that this speaker, Lanzar MAXP154D Max Pro 15-Inch 2000-Watt Small-Enclosure Dual 4-Ohm Subwoofer, or something along those lines would work completely normal with my AMP?
Also, once again, will there be any major drop in sound performance using a speaker such as these?
 

itzdanielp

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Aug 23, 2011
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That is correct, you never want to use more or less ohm's than your amp supports. (although if you have to, you can drive a higher ohm speaker, just at a reduced level)

To measure frequency (hz) you would need an oscilloscope. Measuring RMS or Impedance is very difficult unless you have some way to terminate the signal with a load, which most meters won't. This is why all of the information is included with speakers / amps. However the LowPass Filter on your main amp should be accurate.

Yes, that sub would work great. The fact that it is dual 4ohm is a cool feature, but not necessary with your amp. That is more along the lines if you had a smaller car amp that couldn't drive it so it us bridging the signal at the speaker instead of the amp, so you could use 2 channels.



 

Austin Berry

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Sep 17, 2013
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Final questions before closing the post. Firstly, thank you itzdanielp for all your help. As a college student at ITT Tech majoring in Electrical Engineering, it is always great to get a head start in some classes and helps to hear people clarify certain aspects of things we haven't learned yet. So once again, thank you for all your help

Now for my final questions, could my AMP burn out the previously described sub if wired incorrectly? For example, I wired the speaker to both stereo channels on my AMP instead of bridged the connection. Or if I wire the setup to hook both channels to the bridge on the AMP? Do I need to worry about burning this speaker out with the current AMP I posses?

Will sound quality be reduced being used as a HT sub? (The sub is 15")

And Finally, how loud do you think this speaker will sound in a home environment?
 

Antimatter79

Distinguished
Jul 24, 2009
103
0
18,640
3
Austin, you always run the risk of damaging your equipment if wired incorrectly. You may want to take a little time to fully understand bridging amp channels, series, and parallel wiring of speakers, multiple voice coils, etc. so that you can apply the advice you're given to variable situations. That way, even if you're asking a very specific question about a wiring configuration, you can take the knowledge and apply it to different scenarios, b/c no doubt you are wanting to experiment and try different things. The only choice you have at the moment with that sub and your amp is to wire it stereo which is not ideal.
1 - I would not feed a stereo signal to a subwoofer. Stereo is typically used to create depth and spaciousness of sound, as well as other effects, so the full low frequency range may/may not be fed identically to each channel. Stick to mono for your application.
2- As for burning your speaker out vs damaging your amp, there are lots of variables in play. Are you over driving the equipment, meaning are your amp or sub being driven to the point of distortion or clipping? Is your amp getting sufficient cooling? Those are things that will damage your equipment, aside from improper wiring. As for your amp not sounding good in your friend's car, unfortunately, your amp does not put out anywhere near 1000 watts; it's closer to 95 watts RMS per channel, not sure in bridge mode, most likely just 190 watts. If your friend's subs are truly designed to handle the power you stated (RMS, not max) then they probably have a very low sensitivity as well and your amp would not be enough to push them very loudly without distorting.
3 - The sub will be ok (not ideal b/c it will be in stereo) with your amp but do not set your crossover anywhere near 120 HZ. I didn't see any mention of your main speakers and what they're low end frequency response is, but you generally don't want to run your sub above 80Hz give or take; too much higher bass frequency will cause make your sub bass easily localized instead of seeming to come "from everywhere". Also, the narrower the frequency range for a subwoofer, the cleaner it can play. Also, that subwoofer is advertised as requiring a small enclosure, but that depends on what frequency you want to tune your box to. A car has the benefit of cabin gain; your home will not. It also won't have the same low bass notes in the house as it does in the car with the same enclosure, so you also have to account for that. Download the PDF manual from the website, find an online speaker cabinet calculator, and key in the speaker's measurements. This will give you an expectation of the correct enclosure size for your chosen tuned frequency, whether you go with a sealed or ported enclosure.
 

Autotech67

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Jan 1, 2014
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if you do like I said you will be heard from a block away
 
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