Trying to figure out the amp to speaker power ratio...

[hybridauth_Facebook_100000278936519]

Hi everyone,

I recently got a Denon PMA520AE, it's a pretty nice 2 channel amp that outputs 45W per channel at 8 ohms and 70W at 4 ohms, it got bundled with some large Boston Acoustics CS 260 II speakers that don't work well with it, they start clipping and stuff. (250W speakers). Getting a power amp for them would be ridiculous so I'm thinking about getting some smaller bookshelf speakers.

I am really new at this stuff and I have no idea what the amp to speaker power ratio should be, all I understood is that underpowering speakers is a huge mistake. I've been thinking about some Bowers & Wilkins 686 speakers but they're a bit over my budget, but I guess they should work with my amp. They are also some of the lowest power speakers I've fond for my amp (100W).

 

[drummerman]

Most people use no more than 10 watts into speakers of reasonable sensitivity, 88db+ and that will sound loud. Music Peaks will slightly increase the power required but for the average person with average speakers 40 to 50 clean watts into 8 ohm and 70 or so in to 4 (which is what most modern stand mounts are) is plenty.

However, many modern Stand mounted speakers are perhaps 84 to 85db, not the manufacturer stated 88+ so a multi driver floor stander will usually have the advantage in that respect.

It all depends how loud you listen and yes, clipping is fine way to destroy speakers.

 

[lindsayt]

Alvi Tellez, I have one amp and speaker combination where the ratio of max amp power (continuous into 8 ohms less than 1% THD) to maximum recommended power for the speakers (continuous 24/7) is 6 to 1. And I have another combination where the ratio is 1 to 25. Both combinations sound fine and neither combination is ever used at peak volumes where clipping will occur. There's no magic ratio for amp max power to speaker power handling.

Ideally we could do with you doing the following experiment:

Buy or borrow a calibrated sound pressure meter.

Play your system at volumes where you think clipping is occuring.

Measure the peak volumes at 1 metre from directly in front of one speaker.

Tell us how many db's this is.

This would give us some indication as to whether the distortion you're hearing is due to the power amp section clipping (assuming your power amp is fully working and the manufacturer hasn't exagerated the power specifications and the speaker manufacturer hasn't exaggerated their speaker efficiency or power handling).

It could be that your power amp section is indeed clipping. Or it could be that you're hearing gross distortion from your speakers, or that the pre-amp section is being overloaded by your source and this becomes more apparent as you turn the volume up, or there could be some other source of easily heard distortion in your system, such as your bass cones hitting their end stops or something not working properly - ie needing a repair.

 

[MeanandGreen]

Speaker power ratings are only intended as a guide for which amplifers to use. your speakers power recomandation is 15 - 250 watts. So your Denon fits into that categoary.

The next thing to consider is the sensitivty of the speakers of which yours are 89 db/watt/meter. This is about average and won't require huge amounts of power to produce a loud sound.

I can only assume you have a very large room and are pushing the amplifer beyond it's abilities. Or you just play at seriously high levels?

You could either seek out higer sensitivity speakers which are well into the 90's or even 100's for db/watt/meter. Or you get a much more powerfull amp, or you get higher sensitivty speakers and a more powerful amp together.

 

[Vladimir]

B&W are overpriced and not recommended for people with a tight budget, as well as notorious for needing more amplifier power to get them really going.

In your scenario best to look at Focal, Monitor Audio and Mordaunt Short. I highly recommend the Mordaunt Short Mezzo 6.

 

[hybridauth_Facebook_100000278936519]

B&W are overpriced and not recommended for people with a tight budget, as well as notorious for needing more amplifier power to get them really going.

In your scenario best to look at Focal, Monitor Audio and Mordaunt Short. I highly recommend the Mordaunt Short Mezzo 6.

I just checked out my local online store and they have the Monitor Audio MR1, MR2, BX1 and BX2 in my price range. The MR1 and BX1 are 70W and the other two are 100W, what should I do? I am really afraid to screwing up again and buying another pair of clippy or other incompatible speakers. Could the 70W ones or even the 100W ones work well on my 45W per channel amp?

 

[Vladimir]

The BX2 will certanly do best from the bunch. It has the biggest woofer, cabinet, higher sensitivity and rated at 8 ohms.

 

[MeanandGreen]

B&W are overpriced and not recommended for people with a tight budget, as well as notorious for needing more amplifier power to get them really going.

In your scenario best to look at Focal, Monitor Audio and Mordaunt Short. I highly recommend the Mordaunt Short Mezzo 6.

I just checked out my local online store and they have the Monitor Audio MR1, MR2, BX1 and BX2 in my price range. The MR1 and BX1 are 70W and the other two are 100W, what should I do? I am really afraid to screwing up again and buying another pair of clippy or other incompatible speakers. Could the 70W ones or even the 100W ones work well on my 45W per channel amp?

You are looking at meaningless figures. Forget speaker wattage and look at the sensitivity. The higher the sensitivity the louder the sound per watt of amplifier power.

There are no 'clippy' speakers, that is your amp running out of power. Unless you change to speakers with a sensitivity in the high 90's w/m/db, you aren't going to achieve anything.

 

[hybridauth_Facebook_100000278936519]

There are no 'clippy' speakers, that is your amp running out of power. Unless you change to speakers with a sensitivity in the high 90's w/m/db, you aren't going to achieve anything.

What I meant by "Clippy" is that the Amp wasn't able to deal with them, not that the speakers had anything wrong.

I think I got it now, a 100W speaker with 90db is better than a 250W speaker with 90db because it's more efficient, meaning it can get farther with the power it has available?

But then why 20k$ speakers are insanely powerful (500W+) and still hang around 90db though?

 

[lindsayt]

Have a look at this Alvi.

http://www.whathifi.com/forum/hi-fi/speaker-sensitivity

One thing I would add is that every speaker I've heard of over 97 dbs/2.83v/ 1 metre has been relatively good at recreating dynamics, whilst every conventional coned and domed speaker I've heard of 86 dbs/2.83v/ 1 metre or less efficiency has been poor to mediocre at dynamics.

 

[Craig M.]

I think I got it now, a 100W speaker with 90db is better than a 250W speaker with 90db because it's more efficient, meaning it can get farther with the power it has available?

No. The 90db figure is the efficiency, the figure in Watts is (at a guess) the maximum recommended amp power. It's better to have an amp with more power than you need rather than one with not enough, you're more likely to damage the speakers with an underpowered amp (as the amp is more likely to clip).

 

[MeanandGreen]

There are no 'clippy' speakers, that is your amp running out of power. Unless you change to speakers with a sensitivity in the high 90's w/m/db, you aren't going to achieve anything.

What I meant by "Clippy" is that the Amp wasn't able to deal with them, not that the speakers had anything wrong.

I think I got it now, a 100W speaker with 90db is better than a 250W speaker with 90db because it's more efficient, meaning it can get farther with the power it has available?

But then why 20k$ speakers are insanely powerful (500W+) and still hang around 90db though?

Please forget about speaker 'wattage' it is a totally useless figure. Seriously pay it no attention, forget it.

The db/W/meter measurement tells you how sensitive the speaker is and therefore how easy to achieve volume in the sound per unit of power.

A 90db/Watt/Meter speaker will produce 90db of sound at a distance of 1 meter from the drivers, with 1 watt of amplifier input power. It doesn't matter whatsoever if the speaker is rated at 100W, 250W or 600W. The volume output at 1 meter will be 90db with 1 watt of input power.

The more db/Watt/Meter the speaker rating is, the more volume you will get from your amplifier watts. You won't have to turn the volume dial up as far with a 95db speaker as you would a 87db speaker to achieve the same volume. Therefore less clipping as your amplifier isn't being overdriven.

I can't put it any simpler.