# Amp to speaker ohm difference?



## eagletat (Aug 25, 2013)

I recently picked up a pair of MTX P215H speakers, 4ohm 300 watt RMS 1200 watt total power frequency response 36hz-20khz. My amp\receiver is a Pioneer Elite VSX 70, the manual says the unit supports speakers with a nominal impedance of 6 to 16 ohms. My question is will it hurt or effect my receiver in any way because the speakers are 4 ohm?
Thank you


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## buildsafire (Nov 10, 2013)

I don't necessarily think it will hurt your receiver, but it probably won't sound good, and might hurt your speakers. Not just the ohm rating, but also the wattage of those speakers... plus, they're fairly inefficient - my opinion is not to try it. Good luck


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## tonyvdb (Sep 5, 2007)

They are 96db efficient so not a hard to drive speaker however I would not recommended pushing the volume as 4ohms puts a hard load on the amp to drive. Are you still using a sub with these speakers?


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## buildsafire (Nov 10, 2013)

My bad, I thought I read 86db... sorry about that.


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## eagletat (Aug 25, 2013)

I have 2 subs running on my system, I am still using the AALs at the moment have not hooked the P215s up yet.


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## rab-byte (Feb 1, 2011)

Your speakers draw more power from the amp. This means unlike systems with weak speakers your amp is going to have to work harder to produce sound. This typical manifests as more heat in the amp and you may have a harder time getting bass. Unless you're rocking all night you should be fine but if you notice the receiver getting too hot turn it off and look for an amp.


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## chashint (Jan 12, 2011)

Chances are it's going to work great.
Listen closely as you turn the volume up, if you do not hear distortion everything is fine.
If you do hear distortion turn it down. 
As long as you don't go out of your way to try and break something no harm will come to your AVR or speakers.


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## Tonto (Jun 30, 2007)

As you increase the volume, you will max out the amp faster. This will cause the amp to clip & send distortion to the speaker which will be audible. You can get a seperate amp for not much money that would drive them correctly.


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## eagletat (Aug 25, 2013)

By a seperate amp are you talking about a pre amp?


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## rab-byte (Feb 1, 2011)

eagletat said:


> By a seperate amp are you talking about a pre amp?


No quite the opposite. He is talking about connecting a power amplifier to "preamp out" on your pioneer AVR.


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## Viggen (Dec 31, 2008)

Should be ok.... My 20+ year old denon receiver has been powering bic speakers of similar vintage to the denon which are also 4 ohms ..... And it's been trouble free

Yes the amp will have to work harder, but not that much harder. Be sure the amp has room to breath and it should be fine. Distortion shouldn't be noticeable with only going down 2ohms from its min rating. Only time that it could be a problem to me is if you crank a movie or music for maybe 2+ hours where a lot of heat might be generated. 

Having efficient speakers you shouldn't need a lot of power to get them loud but that depends on how loud you like your music/movies. Not a clue what your receiver is rated at power wise ..... where people get into trouble is when the amp doesn't have enough power to play as loud as the listener wants thus they feed the speakers a bad signal resulting in blown speakers. I have always had the opinion giving speakers more power then they are rated for is safer vs under powering speakers however under powering speakers will not hurt them


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## Viggen (Dec 31, 2008)

And o yea.... Buying a separate amp makes a huge improvement is sound quality. Lots of great brands out there that don't cost a lot and can make those speakers crank plenty loud!

For $300-500 you can get a very solid used amp


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## eagletat (Aug 25, 2013)

By hooking up another amp will that affect my surround sound?


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## nova (Apr 30, 2006)

Should not affect your surround sound, though you may need to get into your set-up menu and adjust your speaker levels.


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## chashint (Jan 12, 2011)

Until the equipment in hand proves itself incapable of the task it is silly to buy additional equipment.
Without knowing much more about the typical volume the OP desires, listening distance, and even type of music typically played it is all just speculation (my opinion included).
With two subwoofers on hand it is very doubtful IMO the AVR will have any issues playing the 4 ohm speakers.
The VSX70 does not have pre-outs so external amps are not an option without replacing the AVR. IMHO 90 watts should be more than enough to get the job done.


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## tonyvdb (Sep 5, 2007)

The VSX70 does have pre outs for the front channels and the sub. Just none for the center and surround channels but that totally un necessary.


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## chashint (Jan 12, 2011)

Good catch.
I missed that on the front channels.
I would still try it out and see how well it works.


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## rab-byte (Feb 1, 2011)

tonyvdb said:


> The VSX70 does have pre outs for the front channels and the sub. Just none for the center and surround channels but that totally un necessary.





chashint said:


> Good catch. I missed that on the front channels. I would still try it out and see how well it works.


This is why I love this place. Team work and kudos!


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## GCG (Aug 22, 2013)

I ran 4Ω Infinity's on a VSX-43TX for years without problems but ran them 'small'. At one time I did run them large for a short while and they did cause the amp to trip out on a thermal overload. Bass management is important. Driving the low end into 4Ω will use up a lot of head room. If you set the fronts to small you should be OK.


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## eagletat (Aug 25, 2013)

OK I have hooked them up everything seems to be good to go. So then I tried hooking up my AALs to the B speaker output with the P215s to the A output also tried switching them. The B output is a lot quieter than the A. I have read and reread the manual can't find anything why this would be. I went into the setup and changed the settings from front wide to A & B with no difference. Are the A output driven with a higher wattage than the B or am I missing something. Also adjusted the channel levels, no difference.


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## tonyvdb (Sep 5, 2007)

Your AALs are not nearly as efficient as the P215s but also the "B" output automatically reduces the output when engaged as you are sharing the same amp across the front channels. This is done to prevent damage. You do not want to run both sets of speaker at the same time ever or you will damage the receiver.


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## eagletat (Aug 25, 2013)

How and why will it damage the receiver?


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## tonyvdb (Sep 5, 2007)

If your running both pairs of speakers at the same time. Yes, you can damage the amp as its then putting even more strain on it.


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## chashint (Jan 12, 2011)

As long as the volume is kept to a reasonable level there should be no issues with running both sets of speakers.
If you hear distortion turn it down.
If the AVR trips off let it cool and don't turn it up that loud again.
You do not have to be afraid of using your equipment, just pay attention until you have excercised it for a while.


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## Viggen (Dec 31, 2008)

I would think depending on how the amp splits the signal can determine if it will do damage to itself or not running both A and B speakers

If the AVR runs the signal in series you would be ok 

If the AVR runs the signal in parallel then yes it will fry it

I have no clue which way it gets the power


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## rab-byte (Feb 1, 2011)

Viggen said:


> I would think depending on how the amp splits the signal can determine if it will do damage to itself or not running both A and B speakers If the AVR runs the signal in series you would be ok If the AVR runs the signal in parallel then yes it will fry it I have no clue which way it gets the power


It should run in series. Can't imaging an engender designing an amp with the ability to run a&b together w/o making the amp able to do that. So yes my guess would be series.


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## eagletat (Aug 25, 2013)

Right why would they design the amp with A&B if its not made to be used that way. In the setup I can change the way the sound is sent to the B outputs, "front height, front wide or just B. I can also bi amp the front or set set up zone 2 but that uses the surround back outputs.


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## rab-byte (Feb 1, 2011)

There may be a term discrepancy popping up. 

Typical it's only stereo receivers with A&B channels. That is one amp to drive both. That was what I'm referring to. 

Surround sound AVRs with 7ch+ sometimes have a pair of assignable terminals that can play independently as channels 6&7 or zone2 or "B" the difference is these have independent amplification allowing you to bi-amp. 

The reason you can't truly bi-amp from B is because you're still drawing from the same amp. So you have the same load and the same voltage drop/resistance.


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## GCG (Aug 22, 2013)

Here's the manual page that deals with the Front Wide/Surround Back relationship. This raises the question - Are you trying to run surround back speakers with the front wide speakers? From what you say I would guess not and the volume difference is sensitivity related since it appears that the surround back amps are used.


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## GCG (Aug 22, 2013)

BTW Here's the link to the manual on the Pioneer site. My previous post was from page 18.

http://www.pioneerelectronics.com/StaticFiles/Manuals/Home/VSX-70_OperatingInstructions021313.pdf


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## GCG (Aug 22, 2013)

One more thing to check is the front speaker levels in MCACC. If there is a substantial boost vs the SB this could be the culprit.


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## rab-byte (Feb 1, 2011)

I should add "B" assignment also means a common volume trim. So as "A" gets louder so does "B"

Your AVR is a 9ch so the assignable speakers become 8&9 or it's a 3zone so 6&7 and 8&9 are both usable pairs; I think it's a 9ch 2zone.


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## GCG (Aug 22, 2013)

Check again. Pioneer lists the VSX-70 as 7.2. I can't find a configuration in the manual where more than 7 full range channels are available simultaneously.


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## rab-byte (Feb 1, 2011)

Count your terminals you have 9
Count your speakers in the literature you posted. See the diagrams you're using up to 9


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## GCG (Aug 22, 2013)

Don't want to get into a war over this. In my previous post where I included that specific manual page the configurations which show 9 channels present have text that states when when FH or FW or "B" speakers are in use then no sound will come from the SB speakers. Pioneer allows for the use of the SB amps for those 3 options in their 7.2 platforms. It places them on terms 8&9 so that if the options aren't desired (for whatever reason) the SB can be placed back into action without rewiring.

Like I said, don't want to get in a fight, just don't want to mis-lead the OP either.


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## rab-byte (Feb 1, 2011)

GCG said:


> Don't want to get into a war over this. In my previous post where I included that specific manual page the configurations which show 9 channels present have text that states when when FH or FW or "B" speakers are in use then no sound will come from the SB speakers. Pioneer allows for the use of the SB amps for those 3 options in their 7.2 platforms. It places them on terms 8&9 so that if the options aren't desired (for whatever reason) the SB can be placed back into action without rewiring. Like I said, don't want to get in a fight, just don't want to mis-lead the OP either.


My bad I misread that.


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## GCG (Aug 22, 2013)

That's cool. It had me scratching my head right after I bought my SC-71. My 43TX was easier. SB doubled for bi-amping the front speakers. So many more options are available on the newer Pioneer stuff in comparison ... but I digress.

Like I said, just want the OP to stay on track.


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