Running 2 ohm speakers parallel

[asilentfire 10+ year member]

I just bought a JVC Arsenal KDA535 head unit and JBL P560C component speakers, and I'm looking for the best amp to power them while still leaving room for a sub and full range speakers in back.

Here are the specs for my JBL P560C component set:

Power Handling, RMS: 75 Watts

Power Handling, Peak: 225 Watts

Sensitivity: 92dB

Frequency Response (±3dB): 55Hz - 23kHz

Mounting Depth: Mid/Woofer 2-1/16" Tweeter 1-3/16"

Impedance: 2 Ohms

I want these speakers to get the full 75 watts RMS.

I was thinking of getting a 4 channel amp, bridging 2 channels to a sub and running the other 2 parallel through some full range speakers to the components up front.

This is my first system and I'm sure there are many things I don't understand, but please bear with me and correct me where I am wrong.

I am looking at 2 amps; the Infinity Reference 475a:

RMS Power Output (Watts x Channels) 75 x 4

Peak Power Output (Watts x Channels) 117 x 4

Power at 2 Ohms (Watts x Channels) 90 x 4

Bridged Power (Watts x Channels) 180 x 2

Minimum Impedance Bridged 4

Minimum Impedance Unbridged 2

and the Infinity Reference 5350a:

RMS Power Output (Watts x Channels) 50 x 4

150 x 1

Peak Power Output (Watts x Channels) 89 x 4

Power at 2 Ohms (Watts x Channels) 60 x 4

Bridged Power (Watts x Channels) 120 x 2

Minimum Impedance Bridged 4

Minimum Impedance Unbridged 2

I would like to use the 4 channel 475a amp as I have a better price on it, but I can get either one fairly cheap.

I want to reach close to 75 RMS to the front speakers, and I'm not sure the 4 channel can do that.

My hope is that I can run the wire parallel through some full range speakers in back at around 60-75 RMS at 4 ohms and still have enough juice left over to give the front components 75 RMS at 2 ohms. I have to do this because I need the other 2 channels to power an amp.

The front components take power priority, I would be okay with the back speakers only getting 35 RMS if need be.

Well that's it, please let me know if the amp fits the bill,

THANKS!

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[MisterDeadeye 10+ year member]

I just bought a JVC Arsenal KDA535 head unit and JBL P560C component speakers, and I'm looking for the best amp to power them while still leaving room for a sub and full range speakers in back.
Here are the specs for my JBL P560C component set:

Power Handling, RMS: 75 Watts

Power Handling, Peak: 225 Watts

Sensitivity: 92dB

Frequency Response (±3dB): 55Hz - 23kHz

Mounting Depth: Mid/Woofer 2-1/16" Tweeter 1-3/16"

Impedance: 2 Ohms

I want these speakers to get the full 75 watts RMS.

I was thinking of getting a 4 channel amp, bridging 2 channels to a sub and running the other 2 parallel through some full range speakers to the components up front.

This is my first system and I'm sure there are many things I don't understand, but please bear with me and correct me where I am wrong.

I am looking at 2 amps; the Infinity Reference 475a:

RMS Power Output (Watts x Channels) 75 x 4

Peak Power Output (Watts x Channels) 117 x 4

Power at 2 Ohms (Watts x Channels) 90 x 4

Bridged Power (Watts x Channels) 180 x 2

Minimum Impedance Bridged 4

Minimum Impedance Unbridged 2

and the Infinity Reference 5350a:

RMS Power Output (Watts x Channels) 50 x 4

150 x 1

Peak Power Output (Watts x Channels) 89 x 4

Power at 2 Ohms (Watts x Channels) 60 x 4

Bridged Power (Watts x Channels) 120 x 2

Minimum Impedance Bridged 4

Minimum Impedance Unbridged 2

I would like to use the 4 channel 475a amp as I have a better price on it, but I can get either one fairly cheap.

I want to reach close to 75 RMS to the front speakers, and I'm not sure the 4 channel can do that.

My hope is that I can run the wire parallel through some full range speakers in back at around 60-75 RMS at 4 ohms and still have enough juice left over to give the front components 75 RMS at 2 ohms. I have to do this because I need the other 2 channels to power an amp.

The front components take power priority, I would be okay with the back speakers only getting 35 RMS if need be.

Well that's it, please let me know if the amp fits the bill,

THANKS!

Well, it looks like you've got a choice to make. If you get a 90x4 4 channel, you'll get the extra 30WRMS(not that much when you think about it) to your speakers, but you'll also have to get another amp when you want to run a sub, which means you'll be using much more current, and losing more voltage. With the 5 channel, you've got all of it right there, but you'll be losing a bit of power.

In my experience, an extra bit of power to the speakers isn't worth the few negatives(one of them including the fact that you'd have to spend a lot more money on more wire and an amp!)

Now, I don't know how good of a deal you'd be getting on those amps, but this will give you your 75x2 @ 2 ohms, and has the extra channel for a sub, and would probably sound better(and it has better crossovers).

Aura RPM5350 RPM Stage 2 Mobile Amplifier 4x50W + 1x150W 269-191

 

[asilentfire 10+ year member]

Thanks, I think I can deal with 30 watts to the rear speakers, but how can I choose which speakers get what power?

Did you just get banned?! I like your pic btw, Alex Grey's Stoned Ape.

 

[MisterDeadeye 10+ year member]

Thanks, I think I can deal with 30 watts to the rear speakers, but how can I choose which speakers get what power?
Did you just get banned?! I like your pic btw, Alex Grey's Stoned Ape.

Three n's. And thank you, you'd be surprised at how many people here ask me about that image.

You can't choose which speakers get what power; it will be pretty much even all the way around, unless you have the gain set lower for one set of channels. Either way, the JBL components will be getting more power than whatever else you get(because of the difference in impedance). Your coaxials in the rear will most likely be 4 ohms, which means if you're using that Aura amp I gave you a link to, they'd be getting 50W or less depending on how you set the gain, and the JBL components would be getting 75W or less depending on how you set the gain.

 

[maylar 10+ year member]

If you parallel front and rear speakers off the same amp channels they'll both get the same power. You can't say, "I want 30 watts to the back and 60 to the front" unless they're on separate channels.

 

[trumpet 5,000+ posts]

The power will be split so the speaker with the lower impedance will get more power. It will constantly change with music playing.

You really don't need to match amp and speaker RMS power ratings. Those JBL speakers will sound fine off less than 75W.

 

[zako 10+ year member]

I just bought a JVC Arsenal KDA535 head unit and JBL P560C component speakers, and I'm looking for the best amp to power them while still leaving room for a sub and full range speakers in back.
Here are the specs for my JBL P560C component set:

Power Handling, RMS: 75 Watts

Power Handling, Peak: 225 Watts

Sensitivity: 92dB

Frequency Response (±3dB): 55Hz - 23kHz

Mounting Depth: Mid/Woofer 2-1/16" Tweeter 1-3/16"

Impedance: 2 Ohms

I want these speakers to get the full 75 watts RMS.

I was thinking of getting a 4 channel amp, bridging 2 channels to a sub and running the other 2 parallel through some full range speakers to the components up front.

This is my first system and I'm sure there are many things I don't understand, but please bear with me and correct me where I am wrong.

First, even if this would work, why would you want to do this? This seems like a recipe for bad sound quality. You lose fader control. Also, depending on which speakers have more sensitivity, the rear or front would end up playing louder. You can't predict that since the factory sensitivity numbers are small signal parameters.

Next, I don't even think this will work. If you wire your 2ohm JBL speaker in parallel with another 2 or 4ohm speaker, then the final impedance seen by the amplifier will drop below 2ohm. At best, your amplifier will run very hot and go into thermal shutdowns. At worse, you will damage the amplifier. What if you wire speakers in series? The final impedance seen by the amplifier will be the sum of all speaker impedances, so this will work. In fact, if the rear speaker is 4ohm speaker, the final impedance will be 6ohms, which is fairly safe for most amplifiers. However, you still have no fader control.

The final problem, is that even without wiring any speakers in parallel, say if you use two channels to run JBL speakers, and the other channels bridged for subwoofer, all amplifier channels internally will see final 2ohm impedance. I would not recommend doing this with a Class A/B amplifier. Class A/B amplifiers already run relatively hot. Force 2ohm impedance on all four channels, and it may go into thermal shutdowns every once in a while on a hot summer day unless extra care was provided to ventilation and proper installation (e.g. not on a side or upside down). I have seen this before. I'd recommend a budget class D amplifier, something like PPI Phantom P900.4. They run more efficiently and cooler.

My personal recommendation is not to worry about rear speakers at all. Do not upgrade them and run them off stereo's amplifier. Most expert tuners attenuate their output so that they don't draw the sound stage to the rear of car. Get a four channel to power your front speakers and subwoofer. If you do want to run more power to the rear speakers, do it the right way and get a 5 channel amplifier, or 4-channel + mono.

 

[asilentfire 10+ year member]

The final problem, is that even without wiring any speakers in parallel, say if you use two channels to run JBL speakers, and the other channels bridged for subwoofer, all amplifier channels internally will see final 2ohm impedance.

That's news to me!

So if the 2 front channels are 2 ohms and the bridged sub is 4 ohms the amp will see all channels as 2 ohms?

I'm probably going to go with a 5 channel, something like MisterDeadeye suggested.. or is that a 4 channel + mono? and whats the difference?