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Thread: Problem matching Sub & Amp Ohm's

  1. #11
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    Quote Originally Posted by tjr1990 View Post
    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?
    You could run bridged but I am always a fan of doing it once, doing it properly...
    You can only use the CA-DA12250 if you wire each subs VCs in series so each sub has a total impedance of 4 ohms, as it's only stable from 4 ohms... 440W RMS x 2 @ 4Ω Bridged. It's a workable solution but not really the preferred one.
    A better solution if you can't find a Fusion monoblock to power both at once is to buy 2 monoblocks... saves bridging. The CA-AM10900 will do 480W RMS x 1 @ 2Ω.
    I would prefer 1 (or even better 2) of the CA-DA12250 as they have plenty of power and allow you to wire your VCs up in whatever configuration you like really.

    Quote Originally Posted by tjr1990 View Post
    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?
    A quote from another forum as to why bridging is bad:
    "You double the distortion (0.5% THD suddenly becomes 1.0% THD) and you quadruple the noise floor (raise noise by 6dB). You also cut the damping in half. "

    Also an extract from 'Audio Asylum - Biamplification Basics'
    Bridging (also called monobridging or monoblocking) is the summing of two channels of an amp to give one higher-powered channel. An amp normally rated at 100W might deliver 300W to 400W when bridged. Because of the summing however, the load on the amp is seen as half of its normal value. In other words, an 8-ohm speaker becomes a 4-ohm speaker load, and a 4-ohm speaker becomes a 2-ohm speaker load. Speaker impedance ratings are nominal only. Actual impedance may dip to a much lower value through part of its range. When an amp's current load has been doubled due to bridging, it can often fail to provide the required amount of current into the load. Sonic effects include harshness in the midrange and highs, and thin bass. In almost all situations therefore, biamping with similar amps will result in better sound quality than bridging. Bridging is best left to professional sound-reinforcement applications, where sound quality is secondary.

    I tested this in my old system, going from a bridged setup to a monoblock and there was a definite improvement.
    If you are investing this much time and money into a show type install, don't cut corners on the sound gear, you will regret it!


    Quote Originally Posted by tjr1990 View Post
    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.
    Cool!! Got some pics anywhere??

  2. #12
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    hmmmm i think i posted but it isnt showing up :\

    EDIT:

    So i did some reading and this thread seems to think i can run my PP-SW120 (2x 2Ohm VC's) off of just 1 VC, so it would have a 2 Ohm load then i could pair it with the CA-AM10900 (480 WRMS @ 2 Ohms) and the sub is rated at 500 WRMS....

    What are your thoughts on this? has anyone tried or done this before?

    http://www.the12volt.com/installbay/...640&TPN=1&PN=1

    ^Thread with the information.
    Last edited by tjr1990; 09-01-2012 at 01:35 PM.

  3. #13
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    Note that a small increase in power doesn't have much effect - ie, to be twice as loud as 440W you need 1760W (4x the power).


    As per that the12volt thread, running only one of 2 voice coils means half the power (output), and an SVC is better.

    AFAIK, DVCs are for greater impedance versatility - eg, a 4Ohm DVC can be wired as 2 or 8 Ohms (full power) or 4 Ohms (half power).
    And there are some tuning possibilities with DVCs by adding resistance etc to the 2nd VC (eg, Q factor), but ask the12volt or others for confirmation or detail.


    A sound system should be designed as a system - ie, select desired speakers or amps and match them - eg, want a 2Ohm 500W RMS speaker, then match a 2Ohm (or lower) stable amp with ~500W RMS output (or more or less depending which advice you prefer - ie, should amp be bigger or smaller than the speakers?).

  4. #14
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    Quote Originally Posted by OldSpark View Post
    As per that the12volt thread, running only one of 2 voice coils means half the power (output), and an SVC is better.

    AFAIK, DVCs are for greater impedance versatility - eg, a 4Ohm DVC can be wired as 2 or 8 Ohms (full power) or 4 Ohms (half power).
    And there are some tuning possibilities with DVCs by adding resistance etc to the 2nd VC (eg, Q factor), but ask the12volt or others for confirmation or detail.
    On the 12volt thread they are under the assumption that you only loose 15-20% of the total power, That takes the sub to 400-425 WRMS. ?

  5. #15
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    Maybe it depends on the subs.
    If one VC handles 250W then 2 VCs handle 500W unless the sub can't handle the combined heat.

  6. #16
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    ^ nope, not half, 10-25% less. page 3:
    http://www.the12volt.com/installbay/...3~TPN~3#366655
    Acutally power handling isn't halved. Here's a quote by Dan Wiggins on this topic:

    "Lastly, power handling isn't compromised by a factor of 2; it's usually decreased 10-25%. The reason is that rarely are you current-limited by the gauge of the wire, and voice coils are wound concentrically so you still have the entire thermal mass working for you. Just that now all the power is dissipated in a single voice coil (typically two of four layers) so you may end up with an inert, non-conducting thermal mass insulating one side of the voice coil. This does not halve power handling, but can reduce it somewhat."
    i got to it reading through the thread because saying the power is halved doesn't make any sense to me...



    regardless, my amps rms rating is equal to my subs max rating, and i am running a single coil on a dvc sub, and have not run into issues yet..

  7. #17
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    That the12volt statement means that one voicecoil can handle the total power - ie, its winding gauge can handle the current.
    My former statement then becomes... if each VC can handle 500W but if the total handling of the sub is 500W (ie, thermal), then if 2 VCs are used, each is limited to 250W. (Or the sum of both equals 500W - eg, 400W + 100W, though that's not IMO a common situation.)

    By the sounds of it, in your sub each VC can handle the total rating. If not, then your single VC is on borrowed time - ie, if its winding gauge isn't sufficient for the total rating, it is hanging on thanks to the total thermal dissipation, but the winding (coil/wire) is hotter than it should be and hence will fail earlier. That assumes running at max power (or rather, above half its rated power).
    But that's where the sub's specs should clarify what the individual VC limits are. EG - the specs state the individual VC power limits and the total power limit (unless there is an industry standard).
    If including the 2nd VC is optional (for full power rating), then each VC should handle the total power.

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