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Thread: Problem matching Sub & Amp Ohm's

  1. #1
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    Problem matching Sub & Amp Ohm's

    Hi all I currently have 1x PP-SW120 http://www.fusionelectronics.com/car...p-12-Subwoofer

    and am looking at getting another one. They each have Dual 2 Ohm Voice Coils, 500w RMS, 2000w Peak.

    Looking at matching with the following amps.....

    Simplest option: CA-DA41400 http://www.fusionelectronics.com/car...nnel-Amplifier

    A 4 Channel Amp that will output 440w RMS x2 @ 4 Ohms, Which will almost perfectly suit the Sub's with a little bit of under powering.

    More Painful Options: CA-DA12250 http://www.fusionelectronics.com/car...lock-Amplifier
    or 2x CA-AM10900 http://www.fusionelectronics.com/car...lock-amplifier

    Now the CA-DA12250 will output 1x 1100w RMS @ 1 Ohms, Only problem is getting the 2x PP-SW120 to 1 Ohm i can get to .5 Ohm or 2 Ohm.

    The CA-AM10900 will output 1x 480w RMS @ 2 Ohms, Same problem getting a single PP-SW120 to run at a 2 Ohm load.


    I looked around and came across some Resistors that i thought could be added in the mix to get my desired load, but wondering if it will effect the quality, the amount of power the sub will receive or anything else it may effect...

    To get the desired load for the DA-DA12250:
    http://www.ebay.com.au/itm/500W-2-Oh...item3a786513c6

    To get the desired load for the CA-AM10900:
    http://www.ebay.com.au/itm/1000W-4oh...item2573ef10e7
    Or
    http://www.ebay.com.au/itm/4-Ohm-4R-...item45ff04a368


    Thanks for any insight and help.
    Last edited by tjr1990; 08-25-2012 at 09:24 PM.

  2. #2
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    Don't use load resistance !
    Plug the sub in order to have 1 ohms each, so 1ohms load for the amp.
    You'll get better results in this configuration.

    Otherwise use another brand material...

  3. #3
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    Quote Originally Posted by riga View Post
    Don't use load resistance !
    Plug the sub in order to have 1 ohms each, so 1ohms load for the amp.
    You'll get better results in this configuration.

    Otherwise use another brand material...
    Information on why you come to this conclusion would be nice...

  4. #4
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    don't ever use load resistors-- after a few minutes at high power levels, those will be hot enough to ignite nearby flammable materials-- like your wood sub box, trunk carpet, plastic tail lights, etc. unless you're looking for a quick way to burn down your car....


    what are you trying to accomplish?

    looking at the wattage is like looking only at the horsepower of a car-- it doesn't tell the whole story.

    a 1,000 w 1ohm setup is like a 1,000 HP car with 1 foot-pound of torque. sure it sounds loud and nasty sitting in a parking lot, but it barely has enough power to get onto the highway.

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    Quote Originally Posted by soundman98 View Post
    don't ever use load resistors-- after a few minutes at high power levels, those will be hot enough to ignite nearby flammable materials-- like your wood sub box, trunk carpet, plastic tail lights, etc. unless you're looking for a quick way to burn down your car....


    what are you trying to accomplish?

    Ahh ok well that makes more sense as to why i shouldn't use resistors.

    And I'm trying to get the best matched Amp from the Fusion line for the Sub/Subs, Whatever Amp will run the driver at or near it RMS to get full potential.

    **Reason for sticking with Fusion is if i build it all up with their gear getting it all nice and stuff they will sponsor you.
    Last edited by tjr1990; 08-28-2012 at 03:05 AM.

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    Ok some concepts here need some fixing!!

    Firstly all audio is rated in IMPEDANCE is not RESISTANCE. Resistance simply put is the resisting of the flow of current. Impedance is the resistance at a certain frequency. So a 1ohm voice coil is NOT the same as a 1ohm resistor as it's 'resistance' will vary with frequency, so you cannot 'load balance' using resistors.

    An amplifiers stability rating (i.e. stable at 1000Wrms @ 2ohm) is the minimum impedance at which it is stable. So you can go higher in impedance (ie 4ohms, 8 ohms etc) but NOT smaller (i.e. 1 ohm).
    So for your subs... if they are DVC and 2ohms per coil, then run each subs VCs in Parallel and then series the 2 subs together. This will give you a total of 2 ohms. You can then use any amp which is stable at 2 ohms or less (i.e. the 1 ohm monoblock you were looking at)

    Also avoid bridging where possible, a single monoblock amp will do a better job (puts on flame suit...).

    I would never buy an amp which had an RMS power rating which was less than the RMS rating of the speakers it was powering. Always get more than needed and then dial back the gains. Its like towing a big boat with a small Daihatsu as opposed to a Nissan Patrol. Sure the Diahatsu may do the job but it will be working extremely hard so is more prone to fail a lot quicker. The Patrol will be a lot more suited to the job and last a lot longer under the load.

    Suggestion:
    Wire the subs as I mentioned to get 2 ohms system impedance. Subs are rated at 500W each, so a total of 1000W rms.
    Use the CA-DA12250 as it is stable at 1 ohm (so will cope with your 2 ohms fine) but is only rated at 850 Watts RMS x 1 @ 2 Ohm. You don't have any headroom at all. BUT it's the best option from the ones you have listed.

    The CA-DA41400 won't do it as it isn't stable at 2 ohms.
    The CA-AM10900 won't do it either as it's only rated at 480 Watts RMS x 1 @ 2 Ohm.


    Any particular reason you decided on Fusion? They fact they rate their amps in PMPO makes me cringe. The specs aren't anything flash either...
    For that sort of money I would look at the Response monoblocks from Jaycar, a better amp for the money in my opinion.

    Hope that helps! Let me know if you have any other questions.

    Pete
    Last edited by Poita; 08-28-2012 at 04:06 PM.

  7. #7
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    Quote Originally Posted by Poita View Post
    Also avoid bridging where possible, a single monoblock amp will do a better job (puts on flame suit...).

    I would never buy an amp which had an RMS power rating which was less than the RMS rating of the speakers it was powering. Always get more than needed and then dial back the gains
    for someone experienced with setting gains, i agree--i run double in my own setup without issues. but it is important to note that setting the gains is only part of the puzzle-- it is also important to set your x-over points correctly as well to reduce the driver from playing out-of-range frequencies that more easily generate distortion.

    for someone who just installs it and runs with whatever settings it came with, i recommend the opposite-- a lower rms amp with a higher rms sub.


    Quote Originally Posted by Poita View Post
    Any particular reason you decided on Fusion? They fact they rate their amps in PMPO makes me cringe. The specs aren't anything flash either...
    For that sort of money I would look at the Response monoblocks from Jaycar, a better amp for the money in my opinion.
    agreed. there are a lot of beautiful amps on the market, and i think it is a shame not to mix and match gear unless they are already giving you the gear for free.

    or, otherwise, what does their sponsorship get you? and what guarantees you'll get a sponsorship by running their gear?

  8. #8
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    Quote Originally Posted by soundman98 View Post
    for someone experienced with setting gains, i agree--i run double in my own setup without issues. but it is important to note that setting the gains is only part of the puzzle-- it is also important to set your x-over points correctly as well to reduce the driver from playing out-of-range frequencies that more easily generate distortion.

    for someone who just installs it and runs with whatever settings it came with, i recommend the opposite-- a lower rms amp with a higher rms sub.
    Agreed, but I would assume if you are putting an amp in you would be taking the time to work out what the little knobs are all about, otherwise it could be a very expensive experiment. A lot of headunits now allow basic crossover settings in their menu setups so setting it on the amp is less critical, but I am not a fan of doing it this way. It does work if you are not sure about the amp end of things though.


    Quote Originally Posted by soundman98 View Post
    agreed. there are a lot of beautiful amps on the market, and i think it is a shame not to mix and match gear unless they are already giving you the gear for free.

    or, otherwise, what does their sponsorship get you? and what guarantees you'll get a sponsorship by running their gear?
    If the gear was average I couldn't give a stuff about sponsorship to be honest... but that's just my opinion.

    tjr1990 - as soundman98 mentioned, have they guaranteed you sponsorship? If so, why not use the best gear they will give you? Matching would also be less of a hassle and they should have plenty of techs who can recommend what to use. Otherwise you may find yourself spending a lot of money and being left high and dry. The only people I know that have been sponsored have insane setups that cost thousands with massively custom door and boot installs... is this what you are aiming for? If so I am surprised that you think $699 for an amp is painful... is on the lower end of amps!

  9. #9
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    Quote Originally Posted by Poita View Post
    Ok some concepts here need some fixing!!

    Firstly all audio is rated in IMPEDANCE is not RESISTANCE. Resistance simply put is the resisting of the flow of current. Impedance is the resistance at a certain frequency. So a 1ohm voice coil is NOT the same as a 1ohm resistor as it's 'resistance' will vary with frequency, so you cannot 'load balance' using resistors.

    An amplifiers stability rating (i.e. stable at 1000Wrms @ 2ohm) is the minimum impedance at which it is stable. So you can go higher in impedance (ie 4ohms, 8 ohms etc) but NOT smaller (i.e. 1 ohm).
    So for your subs... if they are DVC and 2ohms per coil, then run each subs VCs in Parallel and then series the 2 subs together. This will give you a total of 2 ohms. You can then use any amp which is stable at 2 ohms or less (i.e. the 1 ohm monoblock you were looking at)

    Also avoid bridging where possible, a single monoblock amp will do a better job (puts on flame suit...).

    I would never buy an amp which had an RMS power rating which was less than the RMS rating of the speakers it was powering. Always get more than needed and then dial back the gains. Its like towing a big boat with a small Daihatsu as opposed to a Nissan Patrol. Sure the Diahatsu may do the job but it will be working extremely hard so is more prone to fail a lot quicker. The Patrol will be a lot more suited to the job and last a lot longer under the load.

    Suggestion:
    Wire the subs as I mentioned to get 2 ohms system impedance. Subs are rated at 500W each, so a total of 1000W rms.
    Use the CA-DA12250 as it is stable at 1 ohm (so will cope with your 2 ohms fine) but is only rated at 850 Watts RMS x 1 @ 2 Ohm. You don't have any headroom at all. BUT it's the best option from the ones you have listed.

    The CA-DA41400 won't do it as it isn't stable at 2 ohms.
    The CA-AM10900 won't do it either as it's only rated at 480 Watts RMS x 1 @ 2 Ohm.


    Any particular reason you decided on Fusion? They fact they rate their amps in PMPO makes me cringe. The specs aren't anything flash either...
    For that sort of money I would look at the Response monoblocks from Jaycar, a better amp for the money in my opinion.

    Hope that helps! Let me know if you have any other questions.

    Pete
    Instead of running the CA-DA12250 providing 425 WRMS to each sub would i not be better bridging the CA-DA41400 to get 440 WRMS that bit more power?
    or is bridging that unrecommended that i should go the mono?

    As for the choice with Fusion, It started when i got my first car and my Dad brought me splits, 2-ways and a sub + amp active enclosure for it. The sound was great and never had a problem for the few years i had the car. Then when i Contacted Fusion about my plans to create a show car and shown the progress was given a gift pack of merch and some Powerplant Splits, 2-Ways and a 4 Chan Amp the run them for the car as a starter pack. I did contact them about my Amp matching problem and they said the CA-DA12250 Mono, but I just can't see spending another $100 when the CA-DA41400 4 Chan Bridged will give more WRMS to each sub?


    Quote Originally Posted by Poita View Post
    Agreed, but I would assume if you are putting an amp in you would be taking the time to work out what the little knobs are all about, otherwise it could be a very expensive experiment. A lot of headunits now allow basic crossover settings in their menu setups so setting it on the amp is less critical, but I am not a fan of doing it this way. It does work if you are not sure about the amp end of things though.




    If the gear was average I couldn't give a stuff about sponsorship to be honest... but that's just my opinion.

    tjr1990 - as soundman98 mentioned, have they guaranteed you sponsorship? If so, why not use the best gear they will give you? Matching would also be less of a hassle and they should have plenty of techs who can recommend what to use. Otherwise you may find yourself spending a lot of money and being left high and dry. The only people I know that have been sponsored have insane setups that cost thousands with massively custom door and boot installs... is this what you are aiming for? If so I am surprised that you think $699 for an amp is painful... is on the lower end of amps!
    My car is undergoing one of them massively custom makeovers atm, got most of the fiberglass boot done just paused till i get the gear so i can have it all fit nicely.

  10. #10
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    Oh also doing some reading around and found this: http://www.the12volt.com/installbay/...640~PN~5~TPN~5

    Now what if i was to wire 1 VC of a PP-SW120 to a CA-AM10900 that would give me 480 WRMS to that coil and according to what they say on that forum that should be perfectly fine for the sub?

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