# TX-SR 608 driving 4 ohms?



## kadijk (Jan 23, 2011)

I got a great deal on a lsi c center channel from Polk, not realizing it is rated as a 4 ohm speaker. I'm driving it with a Onkyo TX-SR 608, which appears to be tested for continuous 6 ohm use but the specs say nothing about 4 ohm. Should I see this as a problem? Am I asking for trouble? Or is it a non issue? I sure don't want to fry my avr on it's first use. 
Kadijk


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## drdoan (Aug 30, 2006)

As long as you don't get to frisky with the volume, you should be fine. Have fun. Dennis


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## robbo266317 (Sep 22, 2008)

As Dennis said, go easy on the volume and try it at your own risk as my manual states 6Ω minimum.
If it were me I would try it with a 2Ω 10Watt resistor in series with it to be on the safe side. 

Cheers,
Bill.


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## Jungle Jack (Jul 28, 2009)

Hello,
With the 608, Onkyo upgraded the Amplifier Stage over prior 600 Series to meet THX Select2 Certification. You really should be fine. Just be careful at first and gradually raise the Volume and make sure you are not experiencing any sort of Distortion. Moreover, Polk's tend not to be too difficult to drive by AVR's.
Cheers,
JJ


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## kadijk (Jan 23, 2011)

Thanks guys. The resistor idea is interesting to me however I'm not sure of the specifics in making that work. I also looked in my Onkyo manual(last resort) and it's telling me that I can select a setting for speaker resistance, one of them being "less than 6 ohm". I haven't confirmed that this is actually possible but it sounds like a solution to me. Thanks for your help. Any other ideas are totally welcome


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## Jungle Jack (Jul 28, 2009)

kadijk said:


> Thanks guys. The resistor idea is interesting to me however I'm not sure of the specifics in making that work. I also looked in my Onkyo manual(last resort) and it's telling me that I can select a setting for speaker resistance, one of them being "less than 6 ohm". I haven't confirmed that this is actually possible but it sounds like a solution to me. Thanks for your help. Any other ideas are totally welcome


Do not select the 4 Ohm Setting unless you are experiencing Thermal Overloads as it greatly reduces the available power. This Setting is there more to meet UL Certification and to err on the side of caution. Again, Polks tend not to have a very difficult Impedance and are decidedly Designed with AVR's in mind. I really think the Default 6 Ohm Setting will be fine.
Cheers,
JJ


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## tesseract (Aug 9, 2010)

Kadijk - The Polk may dip down to 4 ohms a certain frequencies, but it's average load is higher than 4 ohms. Unless you are playing high level test tones at these frequencies for extended periods, you will be fine.


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## typ44q (Apr 7, 2008)

I am going to have to disagree with most of you, while most polks are very AV receiver friendly the LSI line is a totally different beast and they are very power hungry. The efficiency (sensitivity) was tested at 87dB's and at a nominal 4 ohms with drops to 2.5 - 4 ohms

I was driving a Lsi C with my Onkyo TX-805 which is much more powerful than the 608 and while it sounded ok I did not fully realize its potential until adding a Emotiva XPA3 external amp and WOW it made a HUGE difference.
I think the 608 will work and be safe (at lower volume) but don't expect to get the full potential out of that speaker.


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## Jungle Jack (Jul 28, 2009)

typ44q said:


> I am going to have to disagree with most of you, while most polks are very AV receiver friendly the LSI line is a totally different beast and they are very power hungry. The efficiency (sensitivity) was tested at 87dB's and at a nominal 4 ohms with drops to 2.5 - 4 ohms
> 
> I was driving a Lsi C with my Onkyo TX-805 which is much more powerful than the 608 and while it sounded ok I did not fully realize its potential until adding a Emotiva XPA3 external amp and WOW it made a HUGE difference.
> I think the 608 will work and be safe (at lower volume) but don't expect to get the full potential out of that speaker.


The 805 had an amazing Amplifier Stage for an AVR and while I know the LSi Towers were harder to drive, I am pretty sure the Center Channel is easier to drive than the Mains. As it appeared the OP was only using the LSi Center Channel and not the entire Series, I still think the 608 can drive it.

After looking at the Measurements, the LSi C is 88db Efficient and does dip to 2.36 Ohms at 65hz. As almost all would be using a Subwoofer, this low impedance will not have to be dealt with provided the CC is crossed over at 80hz which it should be anyway. Here is a link to the Measurements: http://www.hometheater.com/content/polk-lsiii-speaker-system-ht-labs-measures

Provided the rest of the Speakers are not LSi Series and the CC is XO'ed at 80hz I do think the 608 can handle it.
Cheers,
JJ


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## typ44q (Apr 7, 2008)

I agree, I would not try to run the CC full range off of that AVR, pairing it with a powered sub will take a huge load off the receiver and sound better.

I think the receiver can handle it and it will not fry it tho it might shut down if pushed too hard, just know that the speaker has a lot more potential in it that requires more power to be realized.


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## Jungle Jack (Jul 28, 2009)

Hello,
The LSi and RSi are a far more ambitious Design than the run of the mill Polk Audio Speakers. Much of this due to them using Vifa's amazing Ring Radiator Tweeter that is used in some ultra expensive Speakers.

Compared to the rest of the Polk Lineup, these Speakers are far more difficult to drive. Regardless. the 608 has a very good Amplifier Stage for an AVR its price. I have long admired the Ring Radiator equipped Polk Speakers and was quite shocked when they first released them. They were even Reviewed in Stereophile and represent tremendous value.

What is yet to be disclosed is what are the accompanying Speakers beyond the LSi C. If the rest of the Speakers are LSi's, then it really might be time to sell the 608 and get an AVR with Preamp Outputs and an Amplifier or perhaps the Emotiva SSP that is being blown out for $499 coupled with a XPA-5.
Cheers,
JJ


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## tesseract (Aug 9, 2010)

typ44q said:


> I am going to have to disagree with most of you, while most polks are very AV receiver friendly the LSI line is a totally different beast and they are very power hungry. The efficiency (sensitivity) was tested at 87dB's and at a nominal 4 ohms with drops to 2.5 - 4 ohms
> 
> I was driving a Lsi C with my Onkyo TX-805 which is much more powerful than the 608 and while it sounded ok I did not fully realize its potential until adding a Emotiva XPA3 external amp and WOW it made a HUGE difference.
> I think the 608 will work and be safe (at lower volume) but don't expect to get the full potential out of that speaker.


I didn't realize that LSi's tested down to the 2 ohm range. I feel that most receivers in general do not allow you to realize the full potential of any worthwhile speaker.


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## Jungle Jack (Jul 28, 2009)

Hello,
Granted this Impedance is at the bottom of the Frequency Range and by setting the Crossover to 80hz, the AVR will not see such a low Impedance. However, the LSi and RSi are quite impressive and really are quite different than the vast majority of Polk Speakers. The Ring Radiator is fantastic and endows these Speakers with top tier Highs.
Cheers,
JJ


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## kadijk (Jan 23, 2011)

Guys, I sure have enjoyed your discussion and comments. I'm glad that when I upgrade my avr, someday, I shouldn't have to upgrade my speakers. The LSi C is the only LSi series speaker I have(it was a steal at $275, I think). My mains and surrounds are the slightly older yet brand new in the box RTi 10's. I am hoping they will all match up ok. The front mains will be bi-amped(as the 608 allows). And I will keep the center crossed over at 80 hz. I should have it all set up in a couple weeks...


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