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Is it safe to have 2 different sized amps pushin the same subs?

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Is it safe to have 2 different sized amps pushin the same subs?

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I kinda think i know the answer to this question, but times are hard and i'm considering options... Anyway i recently purchased a planet audio amp and was a little dissapointed with the output. So, instead of paying a shipping and restocking fee, i'm considering a second amp. The problem is i'm not sure if another one of these amps would be quite enough, and was curious if instead of doing a master/slave opperation, i could manually wire in another amp of a higher output.   O and the current amp is supposed to put out around 1500 rms at 2 ohm. I'm thinking it's more like 700 to 900, maybe... My 2 15s can handle 2000 rms together.

Verified Answer
  • You can't use two different brand amps to power both of your subs together.

    You of course could use the Planet Audio amp to power one sub and some other brand amp to power the second sub - with the understanding that the second sub might be louder and might also hit at the wrong time, leading to cancellation.

    I wasn't sure, but I did some research and it seems that you can only strap amps of the same power output together, so your only option would be one or more additional of the same model amp for strapping (You couldn't strap together a 1500W RMS and a 3000W RMS amp to get 4500W RMS, for example).

    Hope This Helps!!!

    Anyone else have suggestions?

     



    [edited by: TigerHeli at 10:03 AM (GMT -5) on Mon, May 9 2011] typo

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

All Replies
  • matt333
    I kinda think i know the answer to this question

    Me too.

    Give some model numbers please!

    It is ALWAYS best to drive subs from a single channel.  Read about the issues THIS user had with several amps being no louder than 1.

  • You can't use two different brand amps to power both of your subs together.

    You of course could use the Planet Audio amp to power one sub and some other brand amp to power the second sub - with the understanding that the second sub might be louder and might also hit at the wrong time, leading to cancellation.

    I wasn't sure, but I did some research and it seems that you can only strap amps of the same power output together, so your only option would be one or more additional of the same model amp for strapping (You couldn't strap together a 1500W RMS and a 3000W RMS amp to get 4500W RMS, for example).

    Hope This Helps!!!

    Anyone else have suggestions?

     



    [edited by: TigerHeli at 10:03 AM (GMT -5) on Mon, May 9 2011] typo

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • Yeah kinda figured that'd be the answer... I think that i'm going to build separate boxes and wire each sub to its own amp. If i do it that way i can drop my subs to 1 ohm and the amps might be capable of actually pushing them then. And i've already thought of the delay to the second sub. Figured i could use a splitter on the original rcas and run 2 of the same and smaller rcas to each amp. I'm guessing that essentially the signal would be traveling the same length and the subs would respond at roughly the same time. (i think better than using the output that comes on most amps for a second amp, which might make it delay there)

  • Of course the second amp would be of the same make and model too....

  • Just to clarify - signal difference has NOTHING to do with length of the RCA's.

    It comes from either having one sub play the left channel output and the other sub playing the right channel output - or in your case, from using separate boxes and having the sound waves from the subs cancel each other.

    You would probably do better using the same box you have (hopefully with a divided airspace) and adding another terminal cup so you can wire the subs to separate amps.

    Hope This Helps!!!

    Anyone else have suggestions?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • matt333
    I think that i'm going to build separate boxes and wire each sub to its own amp.

    If the amps are strappable than just strap them!  You want both subs to get exactly the same signal.  Running them off different channels means you've got separate gains and filters and it's hard to get them both playing exactly alike.  No wait, it's impossible.

    Give the model numbers.  Please!  I'd really like to help you out!

    matt333
    i've already thought of the delay to the second sub. Figured i could use a splitter on the original rcas and run 2 of the same and smaller rcas to each amp. I'm guessing that essentially the signal would be traveling the same length and the subs would respond at roughly the same time. (i think better than using the output that comes on most amps for a second amp, which might make it delay there)

    Tiger's on point.  The problem with cancellation comes not from delayed signals, it is from 2 or more speakers generating a different signal, or being placed far enough apart that the signals grow out of phase.  I've seen people taking delicate measurements of their speaker wires and wrapping RCA's in long coils to avoid differing lengths.  These individuals claim to be perfectionists or audiophiles or some other self-praising term, and can usually come up with a way of convincing themselves that it's not just a waste of time.  Unfortunately, that's exactly what it is.  Completely pointless.  Don't sweat RCA cables or speaker wires being different lengths.  Electrical signals are relayed through wire just a few ticks slower than light speed. If a signal were strong enough, you could wind one RCA around your car 100 times and still not get as much delay as moving one speaker a single millimeter further away. 

    The individual electrons in a circuit don't actually move very far.  They just push the neighboring electron forward, and that pushes the next one and so on.  Imagine that marbles represent the free electron in copper atoms.  You and a friend who hold different ends of a hollow tube completely filled with marbles.  You want to send your friend on the other end a marble.  Instead of walking over to him, you push a marble into the tube and immediately a marble falls out the other end.  Even if the tube were very long and filled with thousands of marbles, pushing a marble into one end would still instantly push a marble out the other.

  • I like the consept of the electrical signal being marbles, kinda makes since. However, i dont really understand how there could be much of a signal problem/cancellation when the amps would be recieving the same signal, and also considering that my amps would be single channel mono's, and that the subs would only be on seperate sides of the vehicle. Anyway my current amp is a Anarchy 3000.1 Planet Audio, and you can strap them together. The only reason i didn't really like the idea of strapping them is that when strapped they claim to only be stable at only a 2ohm load, while when sepperate they can handle a 1ohm load. But here recently i figured it would probably be best to go ahead and strap the amps... Already have a slight hearing problem. With 2 15s capable of 2000 rms and a 4000 peak between the 2, accompanied with kicker tweeters and infinity kappa 6x9s it dosen't take much to hurt your ears...

  • Also i noticed tiger mentioned that he preffered a divided airspace. What are the benefits to that setup? Does it really matter if the are recieving the same signal, like if they were running off the same amp wired together in a parrellel or series fashion? And how would that be any different from seperater boxes?

  • matt333
    i dont really understand how there could be much of a signal problem/cancellation when the amps would be recieving the same signal



    Amplifiers are not perfect.  They try their best, but output fluctuates across the frequency spectrum.  When sub's warm up, their resistance increases as well, and it's impossible to predict exactly how to set the gain to get them playing exactly alike at all times, at all frequencies, at all temperatures.  It's way easier to simply send both subs a single signal to begin with, that way if the amp's output fluctuates, both subs will be affected the same way. 

    matt333
    The only reason i didn't really like the idea of strapping them is that when strapped they claim to only be stable at only a 2ohm load, while when sepperate they can handle a 1ohm load.


    It shouldn't make any difference.  It's like bridging a stereo amplifier.  Yeah, the final load can only be 2 ohm instead of one, but the amp's also make full power at 2 ohms instead of one.  If each sub is 1 ohm, than wired in series they would be 2 ohm.  You'd get the same output power either way.

    matt333
    Also i noticed tiger mentioned that he preffered a divided airspace. What are the benefits to that setup?


    The benefits are not huge, but the greatest benefit is it makes the setup more reliable.  In the event that one sub stops playing, the other sub will suddenly find itself in an enclosure that is twice the recommended volume.  That can definitely cause it to bottom out.  Be a shame if one sub died, but it would be even worse if it caused the other sub to tear itself apart.  Also, a divider adds a substantial amount of rigidity to an enclosure, and you always want your box to be as strong as you can make it.  Further, using a single enclosure eliminates some cancellation since the subs are closer together, and aimed the same direction.  It makes the overall response more predictable.  Imagine if you dropped 2 stones in a calm lake at the same point.  The waves generated will be larger and propagate in generally a circular fashion.  If you dropped the same 2 stones a meter apart, the waves will mostly work together, but there will be some ripples that intersect oddly and cause cancellation. 

  • i understand that no matter what ohm load the amps would still reach the same peak power point. The difference, as i understand it, is that when in a 1 ohm load the rms value increases. If i'm not mistaking that means clarity at a higher volume. when in either ohm configuration you may can reach the same wattage, but ultimately not the same sound.

    Plus to be completely honest i'm using an old box from a previous setup i had. i admit it was a little big but it was a 5 cubic ft box with one of the same type of 15s i have, on a more powerful amp. That setup operated fine. So that being said i cut out a hole for a secondary sub, and hooked up what i thought to be a larger amp... sadly a supposed 3000 peak 1500rms @ 2 ohm planet audio still pales in comparison to a kicker zx 750.1.    dang planet audio in their over rating and kicker in their under rating. lol    Anyway with a slightly weaker amp i doubt that if one sub failed id be faced with damage to the second... seeing as how one did fine before...

  • However when i do add the second amp, and strap them together there may be a concern for overpowering the remaining sub provided one fails...

    O i also neglected to mention this box is ported and i believe the specs on these 15s (kicker cvx) for a ported box is 3 ft^3 to 5 or 6...

  • J Ro
    Imagine if you dropped 2 stones in a calm lake at the same point.  The waves generated will be larger and propagate in generally a circular fashion.  If you dropped the same 2 stones a meter apart, the waves will mostly work together, but there will be some ripples that intersect oddly and cause cancellation.



    Great analogy.

    Really, the only time it makes sense NOT to have a divided box is with a ported enclosure where you wanted a single port to act for both subs.

    Hope This Helps!!!

    Anyone else have suggestions?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • There is nothing specifically wrong with using the same airspace with 2 subs.  It will work fine (unless something goes wrong), it's just not the absolute optimum way of doing it. 

    matt333
    i understand that no matter what ohm load the amps would still reach the same peak power point. The difference, as i understand it, is that when in a 1 ohm load the rms value increases. If i'm not mistaking that means clarity at a higher volume. when in either ohm configuration you may can reach the same wattage, but ultimately not the same sound.

    I think you're not understanding the advantages of strapping.  If you had 2 PA amps both running 1500 watts at 2 ohms, than strapped they will output 3000 watts at 4 ohms.  There is no loss of RMS power.  Each amp is seeing a 2 ohm load.  It's like bridging.  If a stereo amp makes 100 watts per channel at 2 ohms, than it will make 200 watts bridged to 4 ohms.

  • matt333
    i understand that no matter what ohm load the amps would still reach the same peak power point. The difference, as i understand it, is that when in a 1 ohm load the rms value increases. If i'm not mistaking that means clarity at a higher volume. when in either ohm configuration you may can reach the same wattage, but ultimately not the same sound.

    You are missing a lot of things here.  Peak power is meaningless.  The single amp puts out more RMS and Peak power at 1-ohm than at 2-ohms.  That means more clarity, but you will NOT reach the same wattage at 2-ohms.

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • what you're saying dosen't make any sense to me. From what i understand when you bridge two channels it does indeed double the wattage but it wouldn't be as in your example were a 100 watt load at 2 ohm bridged would create a 200 watt compacity at 4 ohm. I'm pretty sure it would be 100 watts at 2 ohm bridged would create a 200 watt capacity at 2 ohm...    200 watts at 4 ohm would be akin to 400 @ 2 ohm.