any audio savvies on here... active vs passive q

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any audio savvies on here... active vs passive q

Postby jacobrjett » Thu Sep 06, 2012 11:38 am

cannot be bothered signing up to some audio forum so ill see what knowledge is floating about on here first...

doing an install this afternoon for a collegue, hes got a 5 channel amp, which puts out 490wrms @ 2ohm + 4x100rms @ 4 ohm

was gonna run sub to the rear channel (obviously)

but ive come across the idea of running the front components (pioneer tsd1720c) actively.

the amp has a high pass filter on the front channel, and a low pass and a high pass filter on the rear channel.

so i could run the tweets high passed to the front channel, and the mids bandpassed to the rear channel. was thinking bandpass the mids around 80hz-4500hz and the tweets high passed around 4300hz.

does anyone have any experience with active components and is it worth the hassle for average joes system. hes an audiophile by no means he just wants a loud clean setup and i want to do the best setup i can for him considering its not mine - which means i wont have forever to muck around with it. i ask this because im wondering if its worth the effort, or if i should just hook the components and crossovers up directly to the front channel and leave the rear channel blank as originally planned.

does impedence change when you ditch the crossovers?


also, anyone know how twitchy fuses tend to be? im wondering if i can get away with a 60a fuse if i use all 5 channels instead of the original 3 i planned to. with 3 channels it totals 690 rms, with 5 it totals 890 rms, and a 60a x 14.4v = 864 watts of room...


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Postby scotty_ish » Thu Sep 06, 2012 7:06 pm

If hes not going to notice the quality difference I wouldnt bother, plus its harder to tune, where as passive is ready to go out of the box.

If it was me I would look at bridging the front channels to one side, and the rear to the other side, giving plenty of power, just be careful with the gains.
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Postby phoenix » Thu Sep 06, 2012 7:38 pm

I wouldn't bother with an active unless you were tuning the car for sq events. The manufacturer set the crossover points on the passive for a reason.

If the amp is a true 4x100wrms I'd just run the components through the front channels. If the tweeter location isn't optimal and can be partially fixed through a greater control over of the tweeters (over and above what attenuation the passives may allow) then I'd go to an active setup.

In terms of the fuse, unless you are running test tones you are unlikely to blow the 60a. Best to run as low as possible so it blows when it's supposed to - to stop a fire.
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Postby simonlenihan » Thu Sep 06, 2012 7:51 pm

What model amp?

Have a look at what fuses are on the amp itself for a good idea what fuse to run up front.

jacobrjett wrote:with 5 it totals 890 rms, and a 60a x 14.4v = 864 watts of room...

Sure, if your amp is 100% efficient in turning power consumption into power output......
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Postby jacobrjett » Fri Sep 07, 2012 12:04 am

amplifier is a Soundstream l5.1110.

i dont think bridging the front and rear channels for the front speakers is a good idea - it supposedly puts out 2x310rms if you bridge the 4 channels into two. 310rms into a 60rms speaker... id have to be very careful... 100wrms should be plenty...
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Postby jacobrjett » Fri Sep 07, 2012 12:07 am

simonlenihan wrote:What model amp?


soundstream l5.1110

Have a look at what fuses are on the amp itself for a good idea what fuse to run up front.

the amp doesnt actually have any fuses on it... puzzled me too, looked up online and apparently amps of these size (in total it puts out 1110wrms) it can get hard to integrate the fuses into the circuits... so they just rely on a correct install, and the inline fuse...

jacobrjett wrote:with 5 it totals 890 rms, and a 60a x 14.4v = 864 watts of room...

Sure, if your amp is 100% efficient in turning power consumption into power output......


ive never thought of that... so if its putting out 890wrms through the speakers, it could actually be sucking up more then 890wrms through the fuse?
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Postby sergei » Fri Sep 07, 2012 11:12 am

jacobrjett wrote:
simonlenihan wrote:What model amp?


soundstream l5.1110

Have a look at what fuses are on the amp itself for a good idea what fuse to run up front.

the amp doesnt actually have any fuses on it... puzzled me too, looked up online and apparently amps of these size (in total it puts out 1110wrms) it can get hard to integrate the fuses into the circuits... so they just rely on a correct install, and the inline fuse...

jacobrjett wrote:with 5 it totals 890 rms, and a 60a x 14.4v = 864 watts of room...

Sure, if your amp is 100% efficient in turning power consumption into power output......


ive never thought of that... so if its putting out 890wrms through the speakers, it could actually be sucking up more then 890wrms through the fuse?


No. The power rating is bullshit.

The amps are normally at 50-60% Efficiency (unless class D, which is about 90% or so). Which means that max power your amp will output total of about 500W at 60A and 14.4V. Now knowing the fuses have a headroom, your amp will probably consume about 40A max. Which brings down the power to ~350W or so. That is disregarding the THD and what not. It is probably about 50-60W per channel before it gets to 10% THD.

Here how they calculate the power output of an amp to get the "RMS" power that is on sticker:

They only load up only one channel with dummy load (a resistor). They put 1kHz (a tone in voice range) through that channel as input signal and measure current output at desired THD level (normally 10%, to inflate the figures).
Now the realife load is spread across the channel which loads up the power supply (the car amps have DC-to-DC power supplies that bring the voltage up to +/-50V, or 100V rail to rail) which is shared between all channels. Additionally speakers are not resistors and the current is not in phase with voltage (look up power factor), which means the power output also drops. Then you add the whole 20Hz-20kHz range vs 1kHz which also brings down how much and amp can provide.
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Postby scotty_ish » Fri Sep 07, 2012 6:34 pm

jacobrjett wrote:amplifier is a Soundstream l5.1110.

i dont think bridging the front and rear channels for the front speakers is a good idea - it supposedly puts out 2x310rms if you bridge the 4 channels into two. 310rms into a 60rms speaker... id have to be very careful... 100wrms should be plenty...


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Postby jacobrjett » Sat Sep 08, 2012 2:37 am

scotty_ish wrote:
jacobrjett wrote:amplifier is a Soundstream l5.1110.

i dont think bridging the front and rear channels for the front speakers is a good idea - it supposedly puts out 2x310rms if you bridge the 4 channels into two. 310rms into a 60rms speaker... id have to be very careful... 100wrms should be plenty...


chicken :lol: :twisted:


lol, i suppose i am currently putting "1000wrms" into a 350wrms sub at the moment and it seems to be surviving with the gain down.

im sure 100wrms will get the most out of these components anyway though.
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Postby jacobrjett » Wed Sep 12, 2012 12:44 pm

damn, the pioneer tsd-1720 components are deafeningly loud with 100wrms only after 10 minutes of running in, i highly recommend them for anyone that just wants something bloody loud, they may not be top grade audiophile components or anything but they sound bloody good (loud, even and extremely clear, with enough midbass to back up your sub on the kicks) to me.

ive heard them with the recommended 60rms before and they sounded asleep compared to with 100wrms.

$180 with the code "drivestud" on here
http://www.hyper.co.nz/drive/product/speakers/129/comp-6-5-inch-tsd-1720/152527/detail

anyway just went with the components hooked up to the crossovers and running passive off the front channels leaving the rear ones blank, am amazed at how good it sounds. definately no need to run them seperately unless you are into competition etc. IMO. (from a casual audio guy)
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Postby LEAKER » Mon Oct 08, 2012 11:03 am

How have you got on with the gear in your car dude? Done anything to it?
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Postby jacobrjett » Tue Oct 16, 2012 6:32 pm

in my car? I have done nothing! lol. same setup as before. Xplod headunit, pioneer premier sub, earthquake amp, and some components i havnt checked yet.

id like to get a couple new amps and a new headunit, put my type Rs in, and a custom sub box but I dont have the monies :cry:
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