Do subs play in stereo?

[ladysmanfelpz 10+ year member]

Title

I have an accord coupe and want to wire up my system here and am planning only a front stage and sub stage. I want the bass in the cab and don't really care about people in the back seat, plus its just me and maybe one other person most of the time. The plan is to get a 4 channel amp and have the front 2 channels powering my 5.25 door components and tweets on the dash. I'm looking at 6x9 subs for the rear deck, specifically the CDT HD line but if there are any others that fit into the stock location in the rear deck please let me know. Planning on powering them with 50 watts when their rms is 125.

Now would I wire my subs to each their own channel on the other two channels and just set the LPF to 100-120 hz? I'm looking at alpine 4 channels that allow you to independently set HPF/LPF or all pass for both the front and rear channels. Is it fine to not specify they are subs and just low pass them at around 120 so they can play the 30 hz to 120 hz tones even tho they are capable of being a mid driver up to 3000 hz or so? Should 50 watts be sufficient if I'm planning on an extensive sound deadening project without rebuilding the rear deck but only putting MDF rings below the subs? By extensive I mean MLV and the whole business plus I prefer under powering subs for safety and I think 50 watts should be fine as my stock gives quite a bit of boom with just CLD tiles on the rear deck, but I don't want to be handicapping my subs either.

Thats just my plan for you experts out there with an opinion on the build, but back to the main question. How songs will throw sound from left to right or vice versa, will subs do this if they are wired separately, or do most (hopefully some keep stereo in bass) songs cut out the stereo effects below a certain frequency since bass tends to fill the whole room anyway?

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[bbeljefe]

Bass is omnidirectional and is not easily localized so it doesn't really matter if it's in stereo unless you're listening to headphones. You can do it however you like but if you use the subwoofer output from the head unit, it will likely be summed to mono anyway.

Also, it takes a lot more power to make low frequencies play at the same volume level as high frequencies... which is why low frequency channels almost always use larger amplifiers than high frequency channels. If you run your subwoofers on the same power as the mids, you will not have good bass response. Moreover, it is common practice and very safe to over power subwoofers by up to 25%, as the normal impedance rise that happens will prevent your subs from seeing the full amount of power the amp is capable of... regardless of how much power it produces.

Being safe is good but underpowering subs by the amount you're planning to is akin to only driving your car three miles per hour just to be safe. You may not tear anything up but you'll get nowhere in the process.

Lastly, it's best to cross your subs at 80Hz to begin with. 20-80Hz is considered the sub bass frequency range.

 

[ladysmanfelpz 10+ year member]

Okay thanks. I'm no complete noob, but had not heard much of the info you provided. Well the plan is to almost make it a 'sleeper' car audio build using the factory head unit and factory speaker locations with amp mounted under the seat. I would use a line output converter so I would not have or use the sub RCA's, but the rear ones instead. I still think I would want to wire up the subs in stereo since they would be mounted decently apart it may be cool to hear the stereo effect and have a lower ohm load on the amp, but if I can't tell a difference I can wire them up in parallel later.

Well I am planning to run Infinite Baffle since they would be in the rear deck and my understanding is that IB requires less power due to less resistance. Now CDT has rms at 125 but suggests them ran as IB so I'm guessing this is the power they would prefer in a rear deck situation. The thing is I do want a sleeper build, but am not trying to go to extremes on this one. It's my chance on messing with IB set up and more sound dampening. I do not plan on rebuilding the rear deck (unless it can be easily done for fairly cheap) but just speaker rings around and MLV on top to seal off the trunk as much as I can. So the integrity of the rear deck is the big factor I am worried about. I feel two high powered subs with 30oz magnets each might mess up my rear deck. I'm looking for more bass response for sure, but plan to install an EQ as well to really fine tune the SQ of an IB set up. I plan to build an MDF board to completely seal off the rear seats later and may even look into somehow bracing the rear deck from below say from a strut tower bar. If you think the stock rear deck can handle two 125 watts subs on them with moderate sound dampening, that would be great to know. If I'm shooting out of my league, that input is also appreciated so I can look to other strategies of building a decent system for my coupe.

 

[bbeljefe]

I don't see any reason why the package tray can't support the weight you're talking about adding but I would recommend bracing it for the sake of sound quality. If the subs have it flexing away that's a negative for your bass output and SQ.

 

[ladysmanfelpz 10+ year member]

Thanks for the info Jefe. Reason I was thinking about underpowering is cuz I was looking at lightweight crank pulleys, but think I've decided against it especially since audio is my main priority. What are some common ways of bracing a rear deck? Pics or links would be appreciated. Thanks again.