Basic amplifier and speaker theory question

ChefDude

Standard Member
I have a pioneer VSX LX52 a/v amp (rated 150w per channel) and a Focal Dome 5.1 set up (domes recommended Amplifier Power: 25-100 Watts).

My question is, how loud is too loud? What feed back will i get that the kit cannot take any more.

I usually watch/listen to
downloaded TV at -23db
blu-ray trueHD at -18db
DVDs at -17/-18db

sometimes the DVDs are still too quiet, but I am reluctant to increase the volume.... but i have no idea why lol. the speakers have *never* felt blowey/compromised/like they were struggling.

If i amplify a near silent sound at 0db is the amp working really hard to amplify 'not much' or is it not doing much work at all?

I guess the basic question is, if the DVD is too quiet, can I just turn it up regardless of what db figure the amp says?

this must sound very basic, but I defer to the greater knowledgebase here :)

Thanks
 

Badger0-0

Distinguished Member
this must sound very basic

Not really :)

speakers have *never* felt blowey/compromised/like they were struggling.

Speaker-wise, these are the best signs.

Amp-wise, first sign is the protection will kick in and shut it down.

I think you could go louder, but full belt is never advisable.
 

siggy_7

Active Member
Decibels are a logarithmic relationship, for every 3dB change in gain you're halving/doubling the power. So if your amp is delivering 150W per channel at 0dB, then scientifically at -3dB it should only be delivering 75W per channel, which shouldn't damage your speakers from what the specs say. The actual sound volume you get also depends on your speaker's sensitivity of course, which you don't cite. Personally I would stay a few dB below this, but providing you don't hear distortion creeping in you should be fine.
 

dante01

Distinguished Member
Decibels are a logarithmic relationship, for every 3dB change in gain you're halving/doubling the power. So if your amp is delivering 150W per channel at 0dB, then scientifically at -3dB it should only be delivering 75W per channel, which shouldn't damage your speakers from what the specs say. The actual sound volume you get also depends on your speaker's sensitivity of course, which you don't cite. Personally I would stay a few dB below this, but providing you don't hear distortion creeping in you should be fine.

Interesting, but who says that the amp delivers 150 watts when the volume dial is at 0db????


There's no real scientific way to judge this and you must use your common sense and hearing. Simply don't go overboard with the volume and decrease it as soon as you hear any distortion.

Your speakers should be safe within acceptable listening levels, levels which if exceeded would probably damage your hearing as much as your speakers. ;) I'd suggest you not exceed the 0db (85 - 115db in real terms) point on the volume dial. There's no real reason or need to do this anyway ;)
 
Last edited:
Interesting, but who says that an amp delivers 150 watts when the volume dial is at 0db????

I think those figures were just being used as an example:lesson:. But, conversely, who says it doesn't?

Posted before your edit.
 

dante01

Distinguished Member
I think those figures were just being used as an example:lesson:. But, conversely, who says it doesn't?

Posted before your edit.

Well if the amp is outputting 150 watts constantly while the volume dial says 0db then the speakers are the hardest speakers known to man to drive and a more powerful amp is required. Does that sound like the amp will be outputting 150 watts at 0db in reality? You say it yourself, " The actual sound volume you get also depends on your speaker's sensitivity of course…".

Watts are not a measurement of volume or loudness ;)
 
Last edited:

a8ch

Active Member
A historic guide was to keep the gain/volume control under 3/4. This was to try and ensure the amps output was kept in the low distortion band. It is however dependent to speaker design in as much as some models deplete current from an amp more than others.

This is what separates the wheat from the chaff performance wise. I also would advise sticking at 0db or below. In real terms 0db is the reference figure.
 

ChefDude

Standard Member
Thanks all :smashin:

Really informative.

and, for the record, my amp has never risen above -15db and the domes seem to have a sensitivity of 88db :)
 

Mark.Yudkin

Distinguished Member
My question is, how loud is too loud? What feed back will i get that the kit cannot take any more.
I've always worked on the following principle, which seems to work really well for me.

When your wife tells you to "turn the volume down", it's OK.
When your wife yells at you to "turn the volume down", it's loud.
When your wife yells at you to "turn the f***ing volume down" it's too loud.

Of course, YMMV.
 

ChefDude

Standard Member
Mark, we clearly have different women.

In my house
g/f "Turn it up, I can't hear it over the tumble dryer
me "It's on -15, I am not blowing up the amp!"

In my car
g/f "Can you go a bit quicker, the video of the traffic is dull at this speed"
me "Err, we're doing 105, so no!"

(That's mph for people stateside)

so I am the control point. I do love a g/f that loves movies at a healthy sound level though :D
 

siggy_7

Active Member
Interesting, but who says that the amp delivers 150 watts when the volume dial is at 0db????

The OP stated the amp has having a rated output of 150W per channel, so I'm making the assumption that max output is at 0dB. An assumption obviously, but not without reason!
 

dante01

Distinguished Member
The OP stated the amp has having a rated output of 150W per channel, so I'm making the assumption that max output is at 0dB. An assumption obviously, but not without reason!

0db equates to 85 -115db in real terms and as measured from the listening position after calibration. It is not the maximum output of the amp and has no association with a particular wattage or the maximum power the amp can supply. Apart from this, the wattage levels are never constant regardless of where the volume dial is set to. Wattage continually varies dependant on frequencies and the fluctuation in impedance caused by those varying frequencies. It is very unlikely that the amp will need to constantly output 150 watts while the volume dial is set to 0db. In the extremely unlikely event of the amp doing this, a bigger amp is required or the speakers should be replaced with ones easier for it to drive.
 
Last edited:

The latest video from AVForums

Star Wars Andor, Woman King, more Star Trek 4K, Rings of Power & the latest TV, movies & 4K releases
Subscribe to our YouTube channel

Full fat HDMI teeshirts

Support AVForums with Patreon

Top Bottom