Volume and Mathematics Question

[roundmound]

I have an unusual question and please indicate if my logic is extremely flawed.

I own the Rotel 1068, 1095 (200Wx5) and 1060 along with B&W 705s, which are rated at 50-120W power handling. By linear logic, the 1068 at volume 60 means that the 1095 is providing the maximum 120W to the speakers. Am I correct in this logic?

The reason I ask is that I am trying to determine if my equipment has any issues. With the volume on the 1068 at 60, music sounds reasonably loud but movies are at low levels and very anemic (needs volume of 72 for sufficient sound). Through other posts, I determined that room treatments are needed for harshness issues, but quality of sound should not relate to volume. Do you I think have equipment problems or am I being an idiot?

Thanks in advance.

[KEN KAZ]

The sould levels and power levels in stereo equipment are all logritmic, not linear. Every 3dB effectively doubles the power.

I am not familiar with your speakers, butit is a safe bet that they are about 89dB efficent at 1 watt. 89dB is pretty loud. There is a good chance that when you have the preamp set at 60, and the sound is adequate, that you are pushing less than 1 watt.

You have two options here
1. if you are worried about blowing your speakers, dont. its heghly unlikely you will blow a b&w speaker with Rotel amps.....before you blow your eardrums. Most speakers are blown from lack of power (clipping) rather than too much power.

2. if you are interested in the science, then get an SPL meter. put it about 1 m from the speaker. Turn it up until you are at 89 dB (this is loud) you are only pushing a watt.....but you are about to enter diminishing returns. Every 3dB louder you get, you double the power. An increase of 3dB is barely noticable. Here you go
1w---89dB
2w---92dB
4w---95dB
8w---98dB
16w- 101dB
32w--104dB
64w--107dB
128w-110dB
256w-113dB at this point, you are clpping your amp, your speakers sound like hell, and you have blood runnign down your neck....this might be ok, espically if you really like Black Sabbath.

[purplepeople]

It's not uncommon for the players or preamps to divide up output power when switching stereo to multi-channel.

I don't use Rotel, but at that price point, I would expect the 1068 to have level-matching capability when switching from one function to another.

ensen.

[Marcel B]

purplepeople, what do you mean by dividing output ?

The 1068 is a preamp, so I don't understand what you mean.
5-channel power amplifiers (or integrated) often have power supplies that are not big enough to deliver the same amount of wattage in 5 channel mode as in 2-channel mode, but with a preamp it's new to me. (in fact on my 1098 I have to lower the volume when I switch from 2 ch to 5 ch, because with 5 speakers the sound pressure is of course higher)

Marcel B

[Kevin P]

Power isn't being divided, instead most DVDs and 5.1 media are recorded at lower baseline levels in order to increase dynamic range. CDs could also be recorded at these levels but instead they tend to compress the dynamic range to cater to the boom box crowd. This is why a CD tends to be a lot louder than a DVD. The CD will be at the same relative level the whole way through, while the DVD could be soft, then go to loud (during action scenes), etc.

[purplepeople]

Actually, Kevin, that's the impression I got from reading the manual on my Sony DVP-NC650V, as if the power supply is not strong enough for all channels. At least, that's how I remember it when after reading it, I checked around the web and found other examples.... none of which come to mind here at the office. I'll look again when I get home.

ensen.

[roundmound]

Thanks for the excellent and educational answers. Does anyone know of a good website that covers the science of our addictive hobby (obsession)?

[Azeke]

Thanks for the excellent and educational answers. Does anyone know of a good website that covers the science of our addictive hobby (obsession)?

This one is pretty good:

HT

Regards,

Azeke