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@garyclayton,

 

Welcome to the forum.

 

What is the size of your room?

How loud do you like to listen.

 

In general, the amount of amplifier wattage isn't the most important thing, the quality of amplifier wattage is.  In an average size room(2500ft3 or so), as little as 40w/ch will make the RF-7 sing cleanly at pretty high levels provided those 40 watts are "quality" watts.  Quality meaning high current 4 ohm stable.  I once took my 90w/ch@8 ohms, 140w/ch@4ohms Yamaha A-S1000 integrated amp over to forum member @Youthman's home for an RF-7 vs RF-7II vs RF-7III shootout and all three shined with the Yamaha.  His family room/kitchen/dining room is pretty large and the Yamaha had no issues with dynamics and thumping those 10" woofers.  Enter the Acurus A200 and the punch was even more pronounced.  In the same room I bet that 40w/ch would have impressed as well.

 

 

Bill

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Hi Bill, thank you for your advice.  My room is about 300 sq ft. I just bought the RF7-lll towers.  I don't think at this time that I will add surround to the mix.  Primarily the speakers will be for listening to music, records, CD's, etc.  I have a 40 year old Akai AM-2950 amp.  It's rated 130 w per channel @ 4 ohms and 120 w @ 8 ohms. I hear about clipping if not using a compatible amp and don't know what to look for.  So would you thing my existing amp would be okay to use?

thanks Bill, Gary

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As long as there isn't audible distortion from the speakers you'll be fine. 

Very generally speaking, older amps like yours are much better suited at driving speakers like your RF-7s compared to an inexpensive modern surround receiver. 

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the Akai  AM-2950 should still power these speakers reasonably well enough for you to enjoy them 

 

Remember , some people use tube amps of 20-30-40 wpc only -so 120wpc should in theory be that much better -

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Thanks Randy, the only thing I worry about, and don't understand, is the potential damage by clipping.  I've read that to underpower your speakers can damage them by clipping as much as overpowering them.  I wish there was a graph of some sort that made it easy, Clipping for Dummies, that would be for me.

Thanks for your help, Gary

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8 minutes ago, garyclayton said:

Thanks Randy, the only thing I worry about, and don't understand, is the potential damage by clipping.  I've read that to underpower your speakers can damage them by clipping as much as overpowering them.  I wish there was a graph of some sort that made it easy, Clipping for Dummies, that would be for me.

Thanks for your help, Gary

Clipping isn't good. Those RF7llls are power hungry, and will have some lower ohm dips, you'll want plenty of good clean power, your amp should be fine. Do you have anyone that might let you audition an amp or receiver? Some amp/speaker combos just sound better together than others.

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Thanks for your advice, unfortunately I don't have anyone that I can go to trial various amps.

 

With underpowering as long as I'm not blasting the speakers would I be safe to assume that I shouldn't have to worry about clipping?

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1 minute ago, garyclayton said:

Thanks for your advice, unfortunately I don't have anyone that I can go to trial various amps.

 

With underpowering as long as I'm not blasting the speakers would I be safe to assume that I shouldn't have to worry about clipping?

Yes. When your amp starts to struggle, it throws out distortion. You'll hear when distortion is added. Just be easy on the volume knob, and you'll be fine. I'll bet that amp will do fine.

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Wuzzzer I was thinking the same, a lot of the medium to lower priced surround amps don't seem to have much wattage.  My old amp was very powerful and expensive in its day so I'm sure it will offer decent power at 120@8 and 130@4.

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10 minutes ago, garyclayton said:

Thanks for your advice, unfortunately I don't have anyone that I can go to trial various amps.

 

With underpowering as long as I'm not blasting the speakers would I be safe to assume that I shouldn't have to worry about clipping?

 

With clipping, visualize it via a sine wave.  Normally it's a smooth curve up and over the top.  Now if you are trying to push too much power through an amp that cannot handle it, the top of the "mountain" curve ends up getting chopped off flat.  This acts like DC current, always on during that flat part.

 

Your drivers are run on AC, so the voltage goes from high to low 60 times a second.  So your drivers move in and out as per the voltage.  During the clip, it's powering the driver with a constant on.  Drivers don't like that, heat up, and burn out.  (I know I took a lot of shortcuts with this explanation, but they are simply concepts...)

 

My post count was 667 on this one.  The neighbor of the beast.  *<;o)

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Just now, garyclayton said:

Thanks Ceptorman I will give it a try, still have to purchase the wiring.  Speakers just arrived yesterday..

Aren't they impressive? Your amp was built in 1978-80. I'm sure its well built, and it's 4 ohm stable. Get ready to be impressed!

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41 minutes ago, garyclayton said:

Thanks Randy, the only thing I worry about, and don't understand, is the potential damage by clipping.  I've read that to underpower your speakers can damage them by clipping as much as overpowering them.  I wish there was a graph of some sort that made it easy, Clipping for Dummies, that would be for me.

Thanks for your help, Gary

You will hear the clipping.  How loud do you listen?  If not at extreme levels you are probably fine. 

 

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Thanks for the clipping visualization Oicu812, so basically underpowered amps will destroy your speakers if you're asking too much of them.  Any recommendations on an amp for the RF7-lll that would be just to power them for CD's, records, and streamed music?  Also if I decided to go surround as well would you recommend a 2 amp system or is there an AVR that would do a good job for both applications.

Thanks, Gary

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TigerwoodsKhorn, I won't have them to loud for sure.  So the clipping noise is audible so that's a good thing, I'll be sure to listen for it as the unit warms up.

Thanks

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4 minutes ago, garyclayton said:

Thanks for the clipping visualization Oicu812, so basically underpowered amps will destroy your speakers if you're asking too much of them.  Any recommendations on an amp for the RF7-lll that would be just to power them for CD's, records, and streamed music?  Also if I decided to go surround as well would you recommend a 2 amp system or is there an AVR that would do a good job for both applications.

Thanks, Gary

 

I run 7 Klipsch Pro speakers on an Onkyo 7.1 receiver.  It's supposedly rated at 120W per channel, but the RMS rating is probably closer to 85 or 90.  Halfway up the volume is painful and will run you out of my office, long before any clipping occurs.  *<;o)

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1 hour ago, garyclayton said:

That's good to know, this amp us RMS 120 @8 and 130@4 so I should be safe! 

thanks for your help Oicu812

Nice amp.  Wanna sell it?  (j/k)

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