Old receiver, getting new speakers. Some questions.

[blued888]

I am looking to purchase this 5.1 speaker set:

Infinity Primus PC350 Center (10-150 watts power handling/91 dB sensitivity)
http://www.infinitysystems.com/home/products/product_detail.aspx?prod=PC350BK&ser=PRI&Language=ENG&Region=USA&Country=US

Infinity Primus P362 Floorstanders (10-200 watts power handling/93 dB sensitivity)
http://www.infinitysystems.com/home/products/product_detail.aspx?prod=P362BK&ser=PRI&Language=ENG&Region=USA&Country=US

Infinity Primus P162 Bookshelves (10-150 watts power handling/90 dB sensitivity)
http://www.infinitysystems.com/home/products/product_detail.aspx?prod=P162BK&ser=PRI&Language=ENG&Region=USA&Country=US

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

The AVR comes from an HTIB, I sold the satellites and the subwoofer. I have already ordered an eD A2-300 as my new subwoofer.

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? My receiver has an impedance selector switch:

MAIN 4 ohms
CENTER 6 ohms
SURROUNDS 6 ohms

or

MAIN 8 ohms
CENTER 8 ohms
SURROUNDS 8 ohms

I would guess that I need to set the impedance to 8 ohms since specifications of the Primus line indicate a nominal impedance of 8 ohms. However impedance dips on the Infinity Primus 360 (the previous generation) graph show that it goes to as low as 4 ohms during certain frequencies/phase angles.

I have read that tweeters are usually the first to burn out when receiver and speakers are not properly matched. I've read the measurements/graphs on Stereophile for the Infinity Primus 360 but I don't exactly get what they mean. I pretty much know that impedance dips by the speaker require more power/current from the amplifier.

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 Diamond 9's).

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.

If absolutely and necessarily required, my alternative to the old receiver would be to get a new Yamaha RX-V663. But that would entail me to shell out another $300. Which is pretty heavy because the Primus set would cost around $1,000 from where I am (Philippines).

Any help would be greatly appreciated! Thanks!

NOTE: I posted a similar thread on the loudspeaker section, but thought this would solicit even more responses.

 

[blued888]

Additional information:

All speakers, mains/center/surrounds have 8 ohms nominal impedance.

 

[snappy_snoopy]

Additional information:

All speakers, mains/center/surrounds have 8 ohms nominal impedance.

not all speakers have 8 ohms impedance, i have a set which is 6 ohms, and the above is correct it varies over frequency as a speaker acts as a inductor which has a impedance give by

Impedance = 2*pi*f*L,

where f is the frequency and L the inductance, but this equation does not take any protection circuitry in the speaker or shunt internal cabling into account.

I do not have experience with these speakers, but in some receiver cases they have different speaker impedance settings as you have found, by varying these settings all you are doing is changing the thermal cut off for the amplifier, that way you can drive low impedance speakers but the thermal cut off will trigger earlier, so effectively you will not be able to play them as loud or your amplifiers safety switch will turn it off. (at least this is what happens on good receivers).

This piece of information i got from some one else on this website.
Plus another thing to consider is as you have also noticed, what frequency was used for stating the impedance as this will vary between manufacturer.

If you see what i am getting at, if you have a good reciever you most likely have nothing to worry about. But i would check your receiver first before you do that. And your speakers only in rare cases will have a nominal impedance of 4ohms,this is usually the tower speakers (big ones, used for mains)

 

[mike c]

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.

welcome to Audioholics

i'm guessing that salesperson sells Harman Kardon receivers ... correct? "high current" is the sales pitch of the HK/JBL/Infinity group when they were trying to sell me HK over Yammy before.

if you can't afford the receiver yet, i would use your existing receiver, set all speakers to small to protect both the receiver and speakers from too much SPL and use a subwoofer.

but personally i would use the 663

 

[blued888]

not all speakers have 8 ohms impedance, i have a set which is 6 ohms, and the above is correct it varies over frequency as a speaker acts as a inductor which has a impedance give by

Impedance = 2*pi*f*L,

where f is the frequency and L the inductance, but this equation does not take any protection circuitry in the speaker or shunt internal cabling into account.

I do not have experience with these speakers, but in some receiver cases they have different speaker impedance settings as you have found, by varying these settings all you are doing is changing the thermal cut off for the amplifier, that way you can drive low impedance speakers but the thermal cut off will trigger earlier, so effectively you will not be able to play them as loud or your amplifiers safety switch will turn it off. (at least this is what happens on good receivers).

This piece of information i got from some one else on this website.
Plus another thing to consider is as you have also noticed, what frequency was used for stating the impedance as this will vary between manufacturer.

If you see what i am getting at, if you have a good reciever you most likely have nothing to worry about. But i would check your receiver first before you do that. And your speakers only in rare cases will have a nominal impedance of 4ohms,this is usually the tower speakers (big ones, used for mains)

I mean... all the Primus speakers I will be purchasing are rated at 8 ohms nominal. Not speaking for all speakers in general. Sorry about the confusion.

 

[blued888]

Another question...

My amplifier specifications show this:

Dynamic Power per Channel

MAIN, 8/6/4/2 Ω 95/115/140/160W

I was wondering what this means? Does it mean that when the impedance dips to 4 ohms, the amplifier outputs 140w of power? I am guessing this is just for peaks only?

 

[Nomo]

That means that when the receiver is driving 8 ohm speakers the draw on the receiver will be 95 watts and down to 2 ohms it will supposedly be 160 watts, for a about 10 seconds before it over heats and shuts down. Don't take those numbers too seriously. That receiver will do OK with those speakers at moderate levels, but an upgrade would be something to consider in the future.

 

[jcPanny]

Speaker setup.

When you get the new sub, set all speakers to SMALL and a crossover around 80 Hz. When you set the receiver to power the mains full range, it requires much more power.

 

[blued888]

When you get the new sub, set all speakers to SMALL and a crossover around 80 Hz. When you set the receiver to power the mains full range, it requires much more power.

My Yamaha doesn't allow custom tuning of crossover. It sets the crossover automatically for 90hz when speakers are set to small. I'll use that, thanks!