SPLITTERS FOR TWO AMPS

should i run a splitter for two amps, a 800watt and a 200watt, one for subs one for mids, the splitter i have takes one power wire and splits to 2, of course, it is a fused splitter, with two fuses,

will this take power from one amp, and not supply enough power to the 800watt, to push the subs, or it will probally drain the batt, and alternater too? should i run the (batt)power to the amp, and then run (amp) power to the other amp?, or is that series wiring, if some one could touch up on this for me i'd greatly appreciate it

what about runing the (batt)power, to splitter, then power to 200watt, and power to a capacitor to keep a good current on the 800watt for the subs

will this hurt anything, or is there any pointers for this instalation

thank you for the information. the 800wt has 2 15amp fuses, and the 200wt, has a 20amp, so i would it be safe to put a 30amp, in the fuse holder at the battery? the block must be after the first fuse holder, but does it have to be a certain distance, like per say 3 foot from the first fuse. i had a pic but it wont fit.

the capacitor?, would that keep the strain off my alternator, and save my battery, or what do yall think about a battery in the trunk, the gel ones?

dood, there is no way your amp with two 15amp fuses pushed out 800watts. that thing is waaaay overrated.

P= E x I

Power  = voltage X current

if your car's electrical system max voltage is 14.4volts and you have 30amps of protection the max power is 432watts.

https://www.the12volt.com/ohm/page2.asp

even at 2/3s of the fuse rating, which would be 20amps, your wattage would only be 288watts.

(someone correct me if i am wrong)

jdsoldno7, add up the fuses in the amplifiers and you get 50 amperes.  The power wire should be at least 8 gauge (preferably 4 ga.), and a fuse of at least 50 amps in a fusenolder within a foot of the battery.  Power wire runs back to the area where the amps are to be installed.  The distro block is placed near the amps, with 8 gauge wire out to each amp.  The distro should have fuseholders built into it to fuse the two outgoing wires, you can use about 30 or 40 amps for each one.

As for the stiffening cap, I would suggest you try out the system before you install it....for the chance that you can return it and spend the money on more necessary stuff like sound damping.  If you do want to use it or feel it is necessary, place it in line between the distro block and the subwoofer amp, directly before the amp.

If I were a salesman in the field and made my pay on commissions, you can bet that everybody who left my store with an amplifier also had a cap!  But I'm not, and so I advise to find out first if your system actually could benefit from it.  It's an easy add-on.

jon02accord,  I hear that often but it's not correct.  You are talking about finding Power, which in this case is watts from the speakers.  The voltage you used is the car's electrical system voltage, where to find power you would need to use the voltage output of the amplifier.

The job of an amplifier is to make voltage, after all.

The fuses on an amp are there to limit incoming amperage, and must not be confused with the amperage that the amplifier produces.   The input to the amp is low voltage, high current.  The output is high voltage, low current. 

Since the amplifier makes volts, and P = E X I, then the power would come from the amp's output voltage times the current it produces which is determined by the load.

An example:  a USacoustics USB600D mono class D amp has a fuse of 20 amps.  It outputs 200 watts into 4 ohms, and 350 watts into 2 ohms.  By your reckoning, the maximum power output of this amp would be 288 watts, using your formula of 14.4 volts X 20 amps.  Your guess is way off track.  I have measured this particular amp and know its rating is accurate, but you can use any known amplifier and find the error in your reasoning.

Just for info:  Class D amps are much more efficient than class A/B amps and so would need less amperage in the fuses.  Their efficiency allows them to make more voltage with less amperage input, so the fuse rating can't be used to tell much.  And a class A amp, being even less efficient than A/B, will have a larger fuse rating than either of the above...for the same power output.  This makes you realize that the amp's fuse rating has little to do with the power a speaker will ultimately get.

The actual measurement is not voltage.  Voltage is the difference of potential and doesn't equate to power until it meets a resistive load.  What is the resistive load on an amplifier?  The speakers, at a given impedance load.  So "watts" is all proper to use when talking about what an amplifier will do.  It is the load of resistance on the amp that causes it to make the watts. 

You see that when a manufacturer gives a rating for an amplifier, it is given as so many watts into a load of impedance, such as 400 watts @ 2 ohms.  You have the amplifier and the connected speaker(s) combined to get to that.  And yes, there is quite a bit of subjectivity in the industry.  Notice how all power ratings of amplifiers end in even numbers?  75, 150, 400, etc.  What's the chances that every amp has been lab tested and the results always ended up at an even number?  None, of course.

But you understand that the amp fuse ratings do not correspond to it's power output, don't you?  It can be used as a "ballpark guideline", if you have enough experience with amps and have installed enough and tested enough of them to tell.  But it doesn't work in a simple E x I Ohm's formula.  If someone were to guess ballpark, first he has to know the amp's efficiency, which means some of the power is let off as heat.  He would guess the different types of amplifiers using somewhat different criteria.

In this thread, the "800 watts" spoken about had nothing to do with the intent of the question, and so it was not necessary to comment on.  Everybody knows nowadays that a lot of amps are advertised at power ratings  they could only hope to achieve in one millisecond when the solar system is perfectly alligned.  I'm not jumping on you for commenting, but just saying that I wouldn't in this particular subject, as it had no bearing on the question.  My comment to you was to make you (and others) more aware that judging the power an amplifier can make goes far beyond using a simple E x I formula using the car's voltage and the amp's fuses.

no harm no faul, i dont feel that you jumping on me, and i wasnt attempting to flame the 800watt remark either. i can tell you that for some reason both my amps (one of which is an alpine 4ch and the other is a mtx d-class mono) seem to have a wattage output pretty close to 2/3 of the fuse rating. maybe just ironic, i dont know.

and i appreciate you commenting in regards to my asking to be corrected. :)

thanks for the info, i didnt mean the total output, that is the peak of the amp, which i know dont mean alot, it is a viberant lanzar 418, this is the rating, it is a 4-channel, the speakers are rated 4ohms, so if i bridged the two speakers to the 4 channels, + & - on both terminals, it should give me a what load(ohms)?

Use the RMS rating as your guide...4 x 100 Watts RMS at 4 Ohms / 4 x 175 Watts at 2 Ohms .  If you were to bridge a 4 ohm load ( one sub ) onto channels 1 and 2, the load would be 4 ohm bridged.  That is equivalent to the 2 ohm rating because bridging a 4 ohm load is in effect putting a 2 ohm load onto each channel.  You see that the 2 ohm rating for this amp is 175 watts per channel at 2 ohms.  So the sub should get 2 X 175 = 350 watts.

Do the same thing for the second sub onto channels 3 and 4, and each sub should get 350 watts, combined for 700 watts.  According to the rated specs.

Now this is where the guesswork of real power output is guessed at.  The amp is a class A/B with an efficiency of 50 - 55%.  You would look at other known amps of the same type and do a quick comparison.....no math required.  And you would expect that an amp with factory-supplied fuses of that size would indicate that the amp has a true RMS output of about 4 X 45 watts @ 4 ohms, or 4 X 75 watts @ 2 ohms.  So a more realistic guess as to what each sub would actually get in watts would be 150 watts each.

The key for an installation, especially with a suspect-rated amp, is to set the gains on the amp carefully.  Don't allow any distorted sound from those woofers when you are playing your system at full tilt, so that means don't use the amp gains to get more decibels if you think they're not loud enough.

Which means, as I look at it, that I am pretty much in concurrence with jon02accord on the guess of the output of this particular amp.......although I would bump it up a little.  But you know, you can get it set up just right with no distortion/clipping, then get someone to do a reading of the output voltage and you'll know what the output is.  You could do that yourself, too, later on if you feel the need.  We have posted info for such a task here in the forum.  Who knows?  The guesswork might be way wrong and you're reallly getting 200 to 250 watts to each sub. 

stevdart wrote:

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jon02accord,  I hear that often but it's not correct.  You are talking about finding Power, which in this case is watts from the speakers.  The voltage you used is the car's electrical system voltage, where to find power you would need to use the voltage output of the amplifier.

The job of an amplifier is to make voltage, after all.

The fuses on an amp are there to limit incoming amperage, and must not be confused with the amperage that the amplifier produces.   The input to the amp is low voltage, high current.  The output is high voltage, low current. 

Since the amplifier makes volts, and P = E X I, then the power would come from the amp's output voltage times the current it produces which is determined by the load.

An example:  a USacoustics USB600D mono class D amp has a fuse of 20 amps.  It outputs 200 watts into 4 ohms, and 350 watts into 2 ohms.  By your reckoning, the maximum power output of this amp would be 288 watts, using your formula of 14.4 volts X 20 amps.  Your guess is way off track.  I have measured this particular amp and know its rating is accurate, but you can use any known amplifier and find the error in your reasoning.

Just for info:  Class D amps are much more efficient than class A/B amps and so would need less amperage in the fuses.  Their efficiency allows them to make more voltage with less amperage input, so the fuse rating can't be used to tell much.  And a class A amp, being even less efficient than A/B, will have a larger fuse rating than either of the above...for the same power output.  This makes you realize that the amp's fuse rating has little to do with the power a speaker will ultimately get.

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