Numbers to look at when matching amp to subs

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jddavid6409

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When trying to match an amp to subs, different rms watts are listed on subs, so do I look at the 4 ohm number, since my subs are 4 ohms, or do I look at 2 ohms, since the total speaker impedance will be 2.66 (wired parallel/series with two sets of 3 in parallel, and the two sets in series)?

I will be powering six Pyle supposedly 250w rms 4 ohm subs in mono.  I suspect the max watt is 400 as said one time in the description, despite also being said to be 800 in the description, and even on the back of the speaker, since rms is usually about half of the max watts.

Obviously, they are not for a car, but tower speakers.  I want to use audio amps for how much cheaper they are.  I already bought a 92 amp supermicro switching power supply for only $16, but now realize I'll probably need twice that amperage, since I was likely looking at the wrong watt numbers listed on amps.

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I figured it out myself, no thanks to this site.  

I needed around 1500w rms for my six subs, and 500w x 2 for the smaller speakers, so figured out that the ohm numbers to look at on amps depends on the lowest total ohms I can wire my speakers at for a given channel that would not be too low for the amp.  For instance, I could have wired my mono subs several ways to total 0.66, 1.5, 2.66, or 6 ohms.  2.66 would have worked for a 1500w 2ohmm amp, but I didn't like the idea of having to wire the wires coming out of the tower speakers in series, and any amp that powers 1500 rms watts at 2 ohm is normally 1 ohm stable, meaning it's capable of putting out twice the amps I need.  The same is true of 0.66ohms.  Any amp stable at 0.5ohms is going to put out way more than 1500w.

It turns out that since I will be wiring my speakers at 1.5 ohms, the correct watt number to look at isn't even listed.  To find the correct wattage of an amp to match to my 1.5 ohm wired speakers is the rms watts the amp puts out at 1.5 ohms, which is the number between what they put out at 1 ohm, and 2 ohm.  I found a good deal on a perfectly sized one because it is manufacturer refurbished.  It is the Planet Audio PL4000.1D which puts out exactly 1500w rms at 1.5 ohms, because 1500 is between the 2000 rms it can do at 1 ohm, and 1000 at 2 ohms.

Only slight problem with that, is that I may wind up needing to wire them at 2.66 ohms, in which case the amps may not be able to drive my subs to their full bass thumping potential.  Bummer if that is how I have to wire them.  Anyone ever wired an odd number of speakers series/parallel as I'd like to do?  I will be wiring the bottom two in series, wire the top parallel to them, and then wire the two sets of three parallel together.  My question is, since speakers wired in series have higher resistance, and therefore lower volume, will my top speakers play louder, or will being wired to the same output even out the voltage to make them all sound the same?  I assume that is the case, but wonder if anyone has tried it to find out.  Usually speakers wired series/parallel are an even number.

Really, now that I think about it, it makes just as much sense that the top one would be louder, considering that speakers wired in series are seen by the amp as one big speaker.  That, and the fact that I'm pretty sure you can exclude adding resistors to small speakers connected to the same input as large speakers, if you add the right amount of them together in a series.  For instance, like in my case, I wired three 4ohm 250w rms woofers in parallel, and six 4ohm 75w rmf tweeter/mids in series, connected to the same input, and could barely hear anything out of the tweeter/mids, so wired them in two series of three, and the volume was about right compared to the woofers.  It could be that one of the wires was loose when I couldn't hear much of anything out of the little speakers wired in total series, but I don't think so.  I think the volume of them can be adjusted to the larger speakers connected to the same exact input, since wiring them in series increases their resistance.

With that in mind, I am now doubting the idea of wiring them series/parallel/parallel.  I guess if the top speaker does play louder, I can rewire them to the 2.66ohms, but then the amp I ordered may not be able to drive them to their full bass thumping capacity.

 
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:banghead: :clap: :scared: :thumbsup: .......  :hide:

Merry Xmas!

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That musta' been hell to type... I've got a headache from reading it

Hope it sounds great... ought to knock the walls down

 
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