Elementary Question

[Big Piney]

I have a Panasonic amp which is rated 7.1 @ 120 watts per channel. I want to purchase two RS-25 surround speakers which are rated at 75 watts (300 peak) for my L/R backs. Will this be okay as long as I don't crank the volume up close to max? Or should I go for a higher rated wattage? Money is limited for now at $300 for a surround back pair. I'm no electrical engineer so excuse my ignorance. But I know I can get a straight answer here. Thanks.

[Guest BobG]

This is fine for several reasons. Rear speakers rarely receive as loud a signal as fronts, so when you are playing at loud volume overall, the front 3 speakers may see near full power but the rears are usually loafing along far below maximum power.

Also, speaker power handling specs are approximate especially for short term listening. If you were to run a continuous 120 watts to these surrounds for hours on end, they might eventually overheat and suffer some sort of failure, but that is not the nature of audio signals. They are constantly changing in level.

Just as you suggested, be reasonable with maxing out the volume and use the speakers in confidence.

[Daddy Dee]

I'm no electrical engineer, but I did stay at a Holiday Inn Express last night.

You are right in thinking they will be ok as long as you don't crank the volume to max.

It is unlikely that you'd be enjoy the sound pressure levels to drive them with that amount of wattage.

BTW, which Panasonic?

[oldbuckster]

The way I understand it; Underpower is far more dangerous then Overpower; 100 watts to a 75 watt speaker is fine, if you try to power those same 75 watt speakers with 50 watts, and cause the amp/ receiver to clip, that's where you have a problem. If I'm wrong someone will let me know. Underpower is a bigger problem.

[colterphoto1]

Oldbuckster has hit it right on the money. You're far more likely to blow speakers by sending the distorted power from too small an amplifer than the occasional spike they might get from too large an amp, so long as you don't crank it all the time.

[Big Piney]

Thanks guys. That's what I thought. I was born at night but not last night.

Panasonic STR-DE998. Just had it a month and I'm just now figuring it out. My audio/music/video experiences come from the sixties and seventies when two channels was all to reckon with. Now I am reawakening in this seven channel world kicking and screaming all the way.

But I'm learning. This board helps a bunch.

Thanks.

[DizRotus]

Oldbuckster and Colter, IMO, are correct. Clipping is the danger. You're more likely to get clipping from an underpowered amplifier that's being asked to deliver more than it can. Nevertheless, if you overdrive a high powered amplifier to the point of clipping you'll cause damage also. Intuitively, high powered clipping is more dangerous than low powered clipping.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

With efficient horn speakers there should not be any reason to drive even a moderately powered amplifier to the point of clipping. One of the benefits of tube equipment is the way it responds to being overdriven. It's my understanding that its a softer gentler clipped signal than that sent by overtaxed SS gear.

I speak from experience about the evils of high powered SS clipping. In the mid-70s, while a student, I used four 8 ohm Speakerlab SKhorns in a mobile DJ business. With two per side in parallel, that presented a 4 ohm load to the Dynaco ST-400 amplifier, i.e., 300 watts/channel. By the end of each evening the volume was at ear bleed levels; the SKhorns played LOUD and clear. The evidence of high powered clipping was regularly fried T-35s. I must have replaced a dozen T-35 voice coils over two years. Id call EV (then at <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />

600 Cecil St., Buchanan, MI

) on Monday and theyd send out the diaphragm(s) along with an invoice (my recollection is that they were about $15 each). Id be good to go by the weekend. Those were the days when a company like EV would give a student an open account and mail replacement parts without requiring pre-payment.