Question about Watts

[Ready for Ryan]

Hi,

Absolute newbie here. I am planning to buy B&W CM9 speakers and two Emotiva XPA-1 monoblocks for a 2.0 speaker setup.

The CM9 specs say that the 'recommended amplifier power is 30W - 200W into 8Ω on unclipped programme'. And the XPA-1 has Power output of 500 watts RMS @ 8 ohm.

My question is - Is this an incorrect setup? Will the speakers be damaged if connected to this amp?

Thanks in advance.

Ryan

 

[gmichael]

Hi,

Absolute newbie here. I am planning to buy B&W CM9 speakers and two Emotiva XPA-1 monoblocks for a 2.0 speaker setup.

The CM9 specs say that the 'recommended amplifier power is 30W - 200W into 8Ω on unclipped programme'. And the XPA-1 has Power output of 500 watts RMS @ 8 ohm.

My question is - Is this an incorrect setup? Will the speakers be damaged if connected to this amp?
Thanks in advance.

Ryan

Only if you turn it up, and then up, and then as far up as it will go.

 

[JerryLove]

Only if you turn it up, and then up, and then as far up as it will go.

Although somewhat hyperbole, this is essentially correct.

You should be safe up to 112db (peaks can be a bit higher).

 

[XEagleDriver]

JerryL,

How did you arrive at the "112 db" figure?

I am not doubting your math, just interested in learning the process to go from the 200W @ 8ohms spec to 112 db.

r/
XEagleDriver

 

[JerryLove]

89db at 1 watt at 1 meter
99db = 10w
109db = 100w
112db = 200w

There are some other factors: I wouldn't recommend running pink-noise at 112db... but that's a rough idea.

Posted wattage, from reputable brands like B&W, I understand to be about sustained: meaning peaks can safely be higher.
But I may be simplifying. Someone is welcome to correct me.

 

[XEagleDriver]

Got it, Thanks.

89db at 1 watt at 1 meter
99db = 10w
109db = 100w
112db = 200w

There are some other factors: I wouldn't recommend running pink-noise at 112db... but that's a rough idea.

Posted wattage, from reputable brands like B&W, I understand to be about sustained: meaning peaks can safely be higher.
But I may be simplifying. Someone is welcome to correct me.

JerryL,

Thanks, makes sense now!

The piece I was missing was to start with the spec'd sensitivity (89 db @ 1m) which I take it was obtained from the B&W manual/website, since the OP did not reference it.

r/,
XEagleDriver

 

[JerryLove]

The piece I was missing was to start with the spec'd sensitivity (89 db @ 1m) which I take it was obtained from the B&W manual/website, since the OP did not reference it.

Yea, I went out to B&W's site to look it up.

Though it still makes me sad, because I missed getting a trio of CM7s a couple months back for $250 out of my own stupidity.

I will have to drown my sorrow in my new custom builds... whatever year they are finished in (it will be interesting to see what efficiency those end up with, but I've got >900WPC that says they'll be loud)

 

[Ready for Ryan]

Thank you very much guys! Don't want to risk damaging the speakers. I guess I will go for a Rotel RB-1562 then.

Ryan

 

[gmichael]

Although somewhat hyperbole, this is essentially correct.

You should be safe up to 112db (peaks can be a bit higher).

Hyperbole? OK. I achieved the desired effect then.

 

[Quickley17]

I'm not sure how big your room is, or what you plan to do with your speakers, but if you are planning to listen to your speakers at 112 dB, bear this in mind... the 112 dB sound will reflect a loudness of about 100 dB at 3 meters (10 ish feet). For the record, OSHA permits workers 2 hours per day at 100 dB. For reference, a normal conversation is 60 dB and loud music or a "typical concert" (depending on who you ask) is between 95 and 115 dB... If you are like me, and you have a quiet room that you want to listen in (if your room is active and has a lot going on, I'm not sure why you want CM9's in that room) you probably wont be listening to your speakers anywhere near 100 dB.

 

[Ready for Ryan]

I'm not sure how big your room is, or what you plan to do with your speakers, but if you are planning to listen to your speakers at 112 dB, bear this in mind... the 112 dB sound will reflect a loudness of about 100 dB at 3 meters (10 ish feet). For the record, OSHA permits workers 2 hours per day at 100 dB. For reference, a normal conversation is 60 dB and loud music or a "typical concert" (depending on who you ask) is between 95 and 115 dB... If you are like me, and you have a quiet room that you want to listen in (if your room is active and has a lot going on, I'm not sure why you want CM9's in that room) you probably wont be listening to your speakers anywhere near 100 dB.

I don't intend to listen to speakers at that high volumes. The reason I am getting CM9s are so that even if I move to a larger house in the future, I still could use them comfortably. I am looking for a long term purchase.

My question was whether the high powered amps would damage the speakers. And the answer it seems is yes if the volume is turned high. The last thing I want is someone in the house turning up the volume by mistake and damaging the speakers.

 

[Quickley17]

yes, but you can also cause damage with a low powered amp by turning up the volume too high. I think this:

http://emotiva.com/xpa2.shtm

might be a good fit for you. I think it's a lot cheaper than the Rotel too, and you mentioned emotiva already.

 

[Ready for Ryan]

I meant the RB-1572 not 1562. Typo. The Rotels are expensive but I read quite a few positive reviews with the Rotel -B&W combo. The Emotiva XPA-2 sounds like a good choice, especially with their price and return policy I guess its a no-brainer.

 

[Quickley17]

You might want to read about peoples' opinions on Class D (the rotel RB-1572) amplifiers vs Class A/B (Emotiva XPA-2). You could do a search here, or google class D amplifiers.

Also, Rotel and B&W are the same overarching company, so a lot of times you will see the equipment paired in stores that are trying to sell both. Just keep that in mind when you get recommendations and make sure you can tell who is doing the review.

Edit: This might sound like I am biased against Rotel, when in fact I really like their products. I just want to make sure you make the informed decision.

 

[jamie2112]

The Db measurement can be radically different using an "A" weighting and a "C" weighting.A weighting is measured using frequencies that are within the human vocal range.C weighting is really used to measure low end pressure within the listening area.A measurement in the C weighting with sub like most people like to listen to in a room 15x12 could be 110dbCweighted and 95 db A weighted. Also 89db sensativity is a power hungry speaker and thus would require more power than say a 93db sens speaker to reach its full potential.