How would I know if my AVR can drive floorstanders?

[blued888]

I am looking to purchase either one of the following 5.1 speaker sets:

Infinity Primus PC350 Center (10-150 watts power handling/91 dB sensitivity)
Infinity Primus P362 Floorstanders (10-200 watts power handling/93 dB sensitivity)
Infinity Primus P362 Floorstanders (10-200 watts power handling/93 dB sensitivity)

Infinity Primus PC350 Center (10-150 watts power handling/91 dB sensitivity)
Infinity Primus P362 Floorstanders (10-200 watts power handling/93 dB sensitivity)
Infinity Primus P162 Bookshelves (10-150 watts power handling/90 dB sensitivity)

I am using a Yamaha HTR-5540 (75w x 5). http://www.yamaha.com/yec/products/productdetail.html?CNTID=200180&CTID=5000400&ATRID=1010&DETYP=ATTRIBUTE

My question is, will it work fine? Or would the floorstanders require too much power from the amp and damage components in the long run? Will a pair of floorstanders work fine, but not 2 pairs of floorstanders?

I've read somewhere that higher sensitivity speakers are easier to drive. These Infinitys are rated at, at least 90dB. Which are above the usual 88dB or below sensitivity I saw in other speakers I have been looking at (some Wharfedales).

I talked with a salesperson over the phone and he said that my AVR is probably not "high-current capable" so he doesn't know if my AVR can handle the floorstanders. I don't know if he's saying the truth or just a marketing tactic on his part in getting me to buy a new AVR. Sorry, newbie on these stuff.

Any help would be greatly appreciated! Thanks!

 

[Davemcc]

You will be fine. The other spec to look at is the impedence. The Primus are all 8 Ohm and with the high sensitivity, present an easy load to the amp.

Your salesman is not helping you. An 8 Ohm speaker does not need a high current amp, floorstanding or otherwise.

 

[jamie2112]

You will be fine. The other spec to look at is the impedence. The Primus are all 8 Ohm and with the high sensitivity, present an easy load to the amp.

Your salesman is not helping you. An 8 Ohm speaker does not need a high current amp, floorstanding or otherwise.

You are totally right with your statement. The salesman wants to sell you a receiver as well........the first thing to upgrade is your speakers. They are the most important component. Your amp will work fine with the Infinitys..

 

[allargon]

Actually, Wmax said the Infinity P360 (but not necessarily the P362) gets down to 4 Ohms in this post:

http://forums.audioholics.com/forums/showpost.php?p=430078&postcount=47

I have a pair of Infinity P362's. I initially drove them with a POS Sony STR-K790 before I got my HK AVR. There was no clipping with the Sony. Your Yammy will be fine. I would use the additional AVR money on a sub.

 

[blued888]

Actually, Wmax said the Infinity P360 (but not necessarily the P362) gets down to 4 Ohms in this post:

http://forums.audioholics.com/forums/showpost.php?p=430078&postcount=47

I have a pair of Infinity P362's. I initially drove them with a POS Sony STR-K790 before I got my HK AVR. There was no clipping with the Sony. Your Yammy will be fine. I would use the additional AVR money on a sub.

I already ordered an Elemental Design A2-300 for my subwoofer.

Another thing, if the floorstanders are set to large and LFE is also redirected to them because there is no subwoofer, that means they take more load as opposed to having them set as either small or large only and no LFE? In the first scenario, their impedance drops more than the latter scenario (with small setting having the smallest impedance dips). Is that correct?

 

[Joe Schmoe]

The Primuses were designed to be easy to drive. You would be fine if your AVR only put out 15 watts.ch.

 

[allargon]

I already ordered an Elemental Design A2-300 for my subwoofer.

Another thing, if the floorstanders are set to large and LFE is also redirected to them because there is no subwoofer, that means they take more load as opposed to having them set as either small or large only and no LFE? In the first scenario, their impedance drops more than the latter scenario (with small setting having the smallest impedance dips). Is that correct?

Set them to small and cross them at 40Hz if you can.

http://forums.audioholics.com/forums/showthread.php?t=45970

 

[3db]

Set them to small and cross them at 40Hz if you can.

http://forums.audioholics.com/forums/showthread.php?t=45970

reproducing 40Hz is considered large, not small..If the speakers are set small, change the crossover to something like 80 Hz.

 

[PENG]

Another thing, if the floorstanders are set to large and LFE is also redirected to them because there is no subwoofer, that means they take more load as opposed to having them set as either small or large only and no LFE? In the first scenario, their impedance drops more than the latter scenario (with small setting having the smallest impedance dips). Is that correct?

The impedance of a loudspeakers varies with frequency. The phase angle between the voltage (applied to the speaker) and the current also varies with frequency. At a fixed volume (example:0 dB) position, the power demand by a loudspeaker would depend on both impedance and phase angle so you can see that it is not possible to answer your question precisely without seeing the impedance & phase angle vs frequency graphs. I have seen many such graphs in the past and the worst impedance dips and phase angles may or may not coincide with the current demanding low frequencies. So don't be scared automatically by the reported impedance dips, it may or may not matter much. You have to see the graphs first before jumping to conclusion.

Aside from that, as others have suggested, your receiver will do fine, I think you do need a sub and set all your speakers to small. Also, I assume you room is not too big and you don't play your music/movies too loud.

 

[no. 5]

Or would the floorstanders require too much power from the amp and damage components in the long run?

The amount of power needed is determined by a speakers electrical properties, not its size. And speaking of electrical properties, Stereophile measured the 360.

Another thing, if the floorstanders are set to large and LFE is also redirected to them because there is no subwoofer, that means they take more load as opposed to having them set as either small or large only and no LFE? In the first scenario, their impedance drops more than the latter scenario (with small setting having the smallest impedance dips). Is that correct?

If I understood correctly, the answer is no; because a speakers impedance curve is dependent on its own inherent electrical properties, not how much bass is being sent to it. Looking at the Stereophile measurements, if you did want to use the crossover to prevent the amplifier from "seeing" most of the 360s low impedance, they would need to be crossed at around 300Hz to prevent the amplifier from seeing most of the sub 4 Ohm impedance.

The advice to prevent bass from going to a speaker is because of room acoustics and the speakers frequency (and sometimes excursion) limits.

 

[Alex2507]

Here's a direct quote out of the Stereophile measurments article relating to impedance and phase angle:

–45º phase angle at 93Hz will tax amplifiers rated at 8 ohms.)

The bright side is that once I do understand this stuff better, it'll seem like a piece of cake.

 

[no. 5]

The bright side is that once I do understand this stuff better, it'll seem like a piece of cake.

That's the spirit!

 

[Alex2507]

blue888,

I just took a look at the link in post #1 and it seems that in the spec's they are talking about that rec'r dishing out juice to a 2 ohm load. It'll handle the 362's fine if I understand this right.

Personally I would not hesitate to get the Primus line, wait a minute, I did get the Primus line.

Alex

 

[PENG]

Here's a direct quote out of the Stereophile measurments article relating to impedance and phase angle:

–45º phase angle at 93Hz will tax amplifiers rated at 8 ohms.)

The bright side is that once I do understand this stuff better, it'll seem like a piece of cake.

Cosine 45 degree=0.707
Cosine 30 degree=0.866

So at 45 degree, the power factor=0.707, meaning for every 1W required by the speaker, the amp has to deliver 1/0.707=1.414VA. Any 6 or 4 ohm speakers, combine with this kind of power factor will likely be hard to drive unless the tough phase angles and low impedance dips coincide with the less power demanding higher frequencies.

That being said, I doubt you will find too many speakers with this kind of phase angle. I have never see a graph of any speakers that shows 45 degree or higher, regardless of frequencies. That does not mean such speakers do not exist though. (Edit: Thanks to Alex, I have now seen one such speaker, the Infinity Primus 360 )

 

[Alex2507]

Any 6 or 4 ohm speakers, combine with this kind of power factor will likely be hard to drive unless the tough phase angles and low impedance dips coincide with the less power demanding higher frequencies.

I have never see a graph of any speakers that shows 45 degree or higher, regardless of frequencies. That does not mean such speakers do not exist though.

So the higher the phase angle of the speaker at a particular frequency, the harder it is for the amp to drive. Got it.

I didn't do the best job with the Stereophile quote. Here it is again but with impedance factored in:

(The combination of 5.2 ohms and –45º phase angle at 93Hz will tax amplifiers rated at 8 ohms.)

I believe that I have come to a heightened level of counter intuitive understanding. The Primus 360 while being very efficient with a measured sensitivity rating of 91.5dB is still hard to drive @ 93Hz. Looking at the graph in the review I also noticed that everything above 3.5kHz is below 6 ohms and everthing below 9kHz is below 4 ohms.

I'm gonna hook mine up to a 2 channel amp that is 4 ohm stable via the left and right pre-outs on my H/K AVR430 and see how that works.

Thanks for the lesson. Let's hope I do alright on the test Monday.

 

[PENG]

So the higher the phase angle of the speaker at a particular frequency, the harder it is for the amp to drive. Got it.

I didn't do the best job with the Stereophile quote. Here it is again but with impedance factored in:

(The combination of 5.2 ohms and –45º phase angle at 93Hz will tax amplifiers rated at 8 ohms.)

I believe that I have come to a heightened level of counter intuitive understanding. The Primus 360 while being very efficient with a measured sensitivity rating of 91.5dB is still hard to drive @ 93Hz. Looking at the graph in the review I also noticed that everything above 3.5kHz is below 6 ohms and everthing below 9kHz is below 4 ohms.

I'm gonna hook mine up to a 2 channel amp that is 4 ohm stable via the left and right pre-outs on my H/K AVR430 and see how that works.

Thanks for the lesson. Let's hope I do alright on the test Monday.

I read the review and hence edited my post.

 

[blued888]

(The combination of 5.2 ohms and –45º phase angle at 93Hz will tax amplifiers rated at 8 ohms.)

I believe that I have come to a heightened level of counter intuitive understanding. The Primus 360 while being very efficient with a measured sensitivity rating of 91.5dB is still hard to drive @ 93Hz. Looking at the graph in the review I also noticed that everything above 3.5kHz is below 6 ohms and everthing below 9kHz is below 4 ohms.

Uhm, so overall my amp should pretty much still take it okay, right? I have a switch in the back for impedance selection. It's either 8 ohms for main/center/surrounds or main = 4 ohms / center = 6 ohms / surrounds = 6 ohms.

I should be selecting all 8 ohms when I get my speakers because that is their nominal impedance, correct?

I don't want to get $525 for a pair of floorstanders and fry them in the long run. I plan to change the AVR sometime in the future and possibly add an external power amplifier but that might be in 2 to 3 years time because the external power amplifier alone would cost a great bit of money.

Btw, someone told me that it is better to have a more powerful amplifier than having an underpowered amplifier. That means too little power would damage the speakers along the way. Is that true?

 

[Alex2507]

I think you're fine running those with the 8 ohm setting.

I know that $525 is too much for the pair of 362's.

Check eBay and/or google the speakers. Do some searches on this site on them looking for alternatives to $525 for a pair. Shoot, for $525, I'll sell you my pair! Just kidding. Harman Audio on eBay is the place to get 'em. Full warranty and I've dealt with them before so I can say that they are a great. Auction prices are great too.

I've read stuff about strong and weak amps here before but am not well versed enough to speak on it. If you don't get your answer here you can start a thread on it in the rec'r/amp section.

 

[blued888]

Follow-up question on this post. Is there any amplifier near the $200 range that will power the P362s marginally better and enable me to use the speakers' large capabilities (i.e. for the bass extension)? Would one of the following be a significant improvement over my current receiver?

Onkyo TX-SR505 (75w x 7) @ $180 (http://www.us.onkyo.com/model.cfm?m=TX-SR505&class=Receiver&p=s)
Onkyo TX-SR506 (75w x 7) @ $215 (http://www.us.onkyo.com/model.cfm?m=TX-SR506&class=Receiver&p=s)
Onkyo TX-SR574 (80w x 7) @ $199 (http://www.us.onkyo.com/model.cfm?m=TX-SR574&class=Receiver&p=s)
Onkyo TX-SR575 (80w x 7) @ $229 (http://www.us.onkyo.com/model.cfm?m=TX-SR575&class=Receiver&p=s)
Yamaha RX-V559 (95w x 6) @ $199 (http://www.yamaha.com/yec/products/productdetail.html?CNTID=200507&CNTYP=PRODUCT&LGFL=Y)

The Onkyos are 'specified' as "high current low impedance drive" amplifiers. Would that mean it will be able to handle the 4 ohm dips of the P362s?

 

[Joe Schmoe]

I know that $525 is too much for the pair of 362's.

I recently read about the 362s being on sale for $199/pr brand new! Heck, that's less than I paid for my 250s!