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Confused, speaker sensitivity, listening distance and spl


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'ello lovely hifi community.

I have been into hifi for years, but only with some knowledge. I let reviews, hifi shop guys, and friends guide me.

I'm beginning to understand the relationship between sensitivity and required power.  For example, my Proac d20r speakers have a sensitivity of 88.5db/1w/1m. If at same distance I wanted to increase by 3db, my amp would need to output 2w and for an additional 3db I'd need to output 4w, and so on.  Now, nobody sits 1 metre from their speakers.  I am currently about 3-4 metres from my rig and my phone db metre says i'm hitting an average of 81db. My first question is, how does distance affect power requirement to maintain desired db, based on sensitivity and power relationship?

My second question is related to impedance. My Roksan Caspian M2 amp outputs 85w into 8ohm and 125w into 4ohms, but from what I gather speaker impedance is not content, it fluxuates dependent on frequency output, and I guess other factors.  My interpretation of this is that the relationship between sensitivity and db increase is not exponentially liniar. I may need more or less wattage based on dynamics of what i'm listening to at the time. Is my interpretation of this correct?

I'm thinking of upgrading my amp and I'm intrigued how much power and headroom I need to maintain the spl to which i'm used to listening.  For example would a Sugden A21 SE at 33w into 8ohms give around same SPL, based on speaker sensitivity and listening distance?

Cheers

A

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This might help:

http://www.sengpielaudio.com/calculator-distance.htm
.

As a side note, remember not to post any graphs, it tends to make people angry.

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ProAc state the sensitivity as 88.5db for the D2R, but Stereophile say it's nearer to 85db 2.83v/m. Most manufactures seem to be over generous with their sensitivity figures.

https://www.stereophile.com/content/proac-response-d2r-loudspeaker-measurements

Amplifier power:

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Agree with both the comments above. In my view alI I would say is if you really need more volume that you are better looking at getting a new speaker with increased sensitivity than chasing amplifier power . As you state in order to get a 6db increase in volume you need to double the power of your amplifier . This almost never (SET amps aside) starts at single figure power . A small amplifier will be most likely 25 W so then you need a 50 W and then 100 W then a 200 W . I know you get the point but once you are looking a good quality high power amplifiers you are looking at good money for a 100 W and then really serious money above this . You will also I think find that it does not offer that much increase in sound volume certainly not as much as you think . On the other hand a 90db sensitivity speaker will sound so much louder for same input than an 85db one . In fact if you use the same volume setting the 90db speaker may well be far too loud . 

Then and again not everyone agrees with this so take it with the usual yeah right attitude but it is my view . The ability to drive a real loud speaker in a real room with real music and not test tones is often not reflected by the specifications . Some amplifiers quite a few of them Valve units but also in my experience Krell Class A (I have a Mk1 KSA50) and certain other amplifiers have a modest power rating (Krell is 50W) but they drive speakers to very loud levels in quite large rooms . So the ability to make music go loud with an amplifier is not always a simple this is more powerful it will sound louder . One of the loudest combinations I have heard was an KEF Reference speaker (sorry not sure of the model number but I know it had an Isobaric loaded bass) powered by a pair of EAR Monoblock amps . The EAR were rated at 100 W but they controlled the speaker so well that as you increased the volume things just got louder not distorted or over driven so the sound was loud but easy to listen to and you just did not realise how loud it was till you tried to speak and you had to either turn the volume down or shout .

Edited by bencat
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Jon Devore thoughts or just get a pair of speakers like Klipsch & 1watt will fill a large room

John DeVore goes on a rant about the High End Audio lie that inspired him to start his company - YouTube

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32 minutes ago, alboy1975 said:

There's a bit of information missing from the title of that video.

The amount of watts needed depends on speaker sensitivity and load characteristics and on room size.

If you buy a pair of Avangarde Duo Mezzos which have powered woofers and a sensitivity of 107dB then 1W is probably enough.

On the other hand, some speakers are difficult loads to drive and require 200W monos.

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19 hours ago, tuga said:

This might help:

http://www.sengpielaudio.com/calculator-distance.htm
.

As a side note, remember not to post any graphs, it tends to make people angry.

graphs are fun :doh:

  • Haha 1
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17 hours ago, tuga said:

There's a bit of information missing from the title of that video.

The amount of watts needed depends on speaker sensitivity and load characteristics and on room size.

If you buy a pair of Avangarde Duo Mezzos which have powered woofers and a sensitivity of 107dB then 1W is probably enough.

On the other hand, some speakers are difficult loads to drive and require 200W monos.

What he just said . There is a more complex set of factors than simply power and sensitivity .

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