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Discussion Starter #1
My question is this, My buddy is running 4 midbass drivers per door in his tahoe. They are 4 ohm each. all wired in parallel we get a 1 ohm load. The problem being is that obviously his 4 channel amp can't power the 1 ohm load safely. If we were to wire in a 4 ohm resistor before each speaker (series installed) we would get a 2 ohm load in the end correct? Also, is this safe to do so?

He is more of an SPL guy which is why there are 4 per door and 2 tweeters per A pillar. plus 4 18s in the "trunk".


I know we could wire them series parallel to achieve a 4 ohm load and run it that way but he wants all the power he can get. So, 250 watts (MB Quart Onyx 4125 ) per channel at 2 ohms and 125 for tweeters at 4 ohm is what he's looking for.


The resistors would have to be 4 ohm, 50 watt resistors then correct? the gain won't be cranked full obviously because it starts clipping around 3/4 of the way.


Thanks for any help.
 

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Discussion Starter #3
thats why i'm asking the question. i've also found companies who do wire wound high power resistors that would work.


In my head, a 50 watt 4 ohm resistor for each speaker would work because that would be 4 resistors in the series. so, each speaker would make an 8 ohm load now and be rated for 50 watts.

Do you know a better way to do it? i know we could get him a different amp capable of a 1 ohm load. but that means spending about $600 and he already has the 4 channel tucked away and made nice.
 

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Years ago I remember there being autoformers for impedence matching (Rockford?)... I also remember them as being pretty big too.

I agree the resistor inline isn't they way to go. I'd wire it at 4 ohms and call it good. That's a lot of mid-bassery in the doors! :eek: :D
 

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All that resistor is going to do is turn watts into heat.
I 2nd the series parallel solution, or get a bigger amp.

Bret
PPI-ART COLLECTOR
 

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series 2 pairs of mids per door for an 8ohm load per PAIR, then wire parellel and achieve a 4ohm load per corner..


Adding a resistor is ****ing silly... the power WILL be shared by all devices connected, so as stated, 1/2 the power will simply be wasted turnind to HEAT...

Dumb...
 

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Wiring in a resistor is pointless. It will absorb power from the rest of the drivers, and convert it to heat. Makes no sense.
 

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The only time a resistor really works is if you have two drivers and want to cut one back, its the cheap way to do it without a L pad or fader of some kind. Such as running front and rears parallel and putting resistors on the rears to make the front stage more and still having sound in the rear. That way the resistor will tend to force more of the power to the front speaker rather than wasting it in the resistor.

I'd recommend you wire them two pair each in series and parallel those for a 4 ohm load, then find an amp to bridge on them that will get you a 2 ohm load per channel at the amp (4 ohm bridged). Get another amp for the tweeters/etc.

You really have no other choice other than running them 4 ohm, the resistor will just eat the power so the speaker does not see it so you get no advantage that way. Otherwise just try 4 ohm it might not work that bad with the added dB from quads.
 

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Bigger amp or more amps is your best solution. If you go and get some tiny little 4 ohm resistors and wire those things in they're gonna get quite hot... Then eventually fail and mess up your system. Or they'll get hot enough to go boom/catch fire.
 

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it will take some of the power out of the drivers themselves.
 

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Actually if he wires the resistor in to make it a 2 ohm load, the drivers will see the same or less power than they would in a 4 ohm load without a resistor. Also, the amp will run hotter and less stable, and it's a bigger strain on your electrical system.
 

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Actually if he wires the resistor in to make it a 2 ohm load, the drivers will see the same or less power than they would in a 4 ohm load without a resistor. Also, the amp will run hotter and less stable, and it's a bigger strain on your electrical system.
if there is only 1 speaker and a resistor involved. But the advantage would be from having multiple speakers to reach a safer ohm load? correct
 

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All that resistor is going to do is turn watts into heat.
I 2nd the series parallel solution, or get a bigger amp.

Bret
PPI-ART COLLECTOR
Yep, makes no sense. Your trying to gain power but all the gain will be lost in the resister its self.
 

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Discussion Starter #14 (Edited)
Deleting old post... not worth getting into virtual arguments with people.


Thanks to those who stated exactly why it won't work. I originally said to bridge the 4 channel and leave gain low for headroom.

Those who feel the need to swear, thank you for the color.
 

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Well "in theory" it gets full power out of your amp, but unfortunately that does not equate to getting more power to the speakers in question. As has been stated in several different levels of politeness: the resistors will change the load to the amp but will more or less (depending on the frequency and impedance swing) eat up the extra power your amp will be producing and turn it in to heat instead of the more delightful music.

Best solutions for louder music are:
A) Run it series/parallel at 4 ohm and relish in the fact that at that load your amp should live a long life and pass of natural causes
B) Get a larger amplifier and go with the series/parallel configuration for 4 ohm
C) Find an amp that supports 1 ohm stereo (kind of rare in a full-range amp nowadays) and purchase that
D) Assuming you have an above average/overbuilt 4 channel amp (I'm probably going out on a limb here since you have not named any brands or model numbers yet) run it 1 ohm stereo and make sure it has decent cooling. As long as he doesn't listen to sine waves non-stop most amps worth their salt can safely run mids & highs below their ohm rating. I would only recommend this for someone that was pretty responsible with their listening habits and can positively identify what it sounds like when equipment is being overdriven (and actually has decent equipment, as most cheaper stuff in the past few years is designed with no built-in headroom and runs within an inch of it's life).
 

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Discussion Starter #16
Well "in theory" it gets full power out of your amp, but unfortunately that does not equate to getting more power to the speakers in question. As has been stated in several different levels of politeness: the resistors will change the load to the amp but will more or less (depending on the frequency and impedance swing) eat up the extra power your amp will be producing and turn it in to heat instead of the more delightful music.

Best solutions for louder music are:
A) Run it series/parallel at 4 ohm and relish in the fact that at that load your amp should live a long life and pass of natural causes
B) Get a larger amplifier and go with the series/parallel configuration for 4 ohm
C) Find an amp that supports 1 ohm stereo (kind of rare in a full-range amp nowadays) and purchase that
D) Assuming you have an above average/overbuilt 4 channel amp (I'm probably going out on a limb here since you have not named any brands or model numbers yet) run it 1 ohm stereo and make sure it has decent cooling. As long as he doesn't listen to sine waves non-stop most amps worth their salt can safely run mids & highs below their ohm rating. I would only recommend this for someone that was pretty responsible with their listening habits and can positively identify what it sounds like when equipment is being overdriven (and actually has decent equipment, as most cheaper stuff in the past few years is designed with no built-in headroom and runs within an inch of it's life).


thanks for the input.

the tahoe has dual mechman alternators, up front with 8 XS 3100s under the "trunk" in a bracket similar to Steve Meade. (i hate using him but thats the only person that everyone out there has heard of).

Then a Stetsom 14K powering 4 SSA Zcons for competition. He knows what to listen for in systems and such, just wanted some help with the doors. I can't remember off hand what the door mids are, i just know that they're 4 ohms speakers.

He has the MB quart 4125 4 channel installed already that we're going to bridge and run to the doors and then a polk amp that we're going to run to his pillars. I just wanted to see if it were possible to safely do a resistor in line with speakers or not. A simple no with reason why or yes and reason why was all i was asking for. I got that and thank you guys for the help.
 

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Seems like you got it covered now. As a side note: if you are going to bridge that 4-channel amp just for the mid-basses the series/parallel config (4 ohm final load at each door) should yield full power from your amp w/o having to resort to resistors.

Good luck with the upgrades, sounds like a monster system :)
 

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Discussion Starter #18
Seems like you got it covered now. As a side note: if you are going to bridge that 4-channel amp just for the mid-basses the series/parallel config (4 ohm final load at each door) should yield full power from your amp w/o having to resort to resistors.

Good luck with the upgrades, sounds like a monster system :)
thanks man, it loves the competitions but sad news is that he got T-boned today and truck is totaled. so we're ripping it all out and he's looking into getting an Astro Van and only 2 18s..... wow do metro detroit drivers suck.
 

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AS long as everyone's OK. Sometimes it's fun to start over (though not really when it wasn't your idea) :(
 
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