Wadia S7i direct to amp

so, a 3dB reduction in voltage corresponds to a 6dB reduction in power.

wrong! a 3dB reduction in POWER corresponds to a 6dB reduction in VOLTAGE.

i took a look at the wadia manual, and i think that there is an error in the manual.

I had a good laugh at this one!!! :-)

it appears that there is actually a 1dB change in volume for each step in the digital volume control.

Oh, is it??
so, now we have 100 steps & 100dB of volume control??
You better call up Wadia & tell them that they actually have 100dB of volume control & not 50dB.....

Paperw8: a 3dB reduction in voltage corresponds to a 6dB reduction in power.

Bombaywalla: wrong! a 3dB reduction in POWER corresponds to a 6dB reduction in VOLTAGE.

I haven't taken the time to read through most of this thread, but I'll just say with respect to the quoted comments that neither is correct.

A 3db reduction in power corresponds to a 3db reduction in voltage, for a given impedance. A 6db reduction in power corresponds to a 6db reduction in voltage, for a given impedance.

To see that, consider that a 3db reduction in voltage corresponds to the voltage being reduced by a factor of 0.707. Since, as I think we all agree, P = Esquared/R, that 3db reduction in voltage results in power being reduced by a factor of 0.707 x 0.707 = 0.5, which is also 3db.

Regards,
-- Al

12-05-10: Bombaywalla
wrong! a 3dB reduction in POWER corresponds to a 6dB reduction in VOLTAGE.

unlike much of the subjective discussion in this forum, this is a factual matter; your *opinion* on the matter is irrelevent to the actual *facts*.

12-05-10: Almarg
I haven't taken the time to read through most of this thread, but I'll just say with respect to the quoted comments that neither is correct.

A 3db reduction in power corresponds to a 3db reduction in voltage, for a given impedance. A 6db reduction in power corresponds to a 6db reduction in voltage, for a given impedance.

the reason why impedance is not considered is because you are generally looking at power at a given point. for example, when you measure output power, you are always measuring power at the output terminals, so there is no difference in impedance. in this case, what we are describing is the effect of the wadia digital volume control on either the voltage output level or on power output level. so if you do a decibel measurement on voltage, the voltage level is halved at each 3dB increment; if you do a decibel measurement on the power level, that too is halved at each 3dB measurement, but if you look at power as a function of voltage and perform the power measurement AS A RATIO OF THE CORRESPONDING VOLTAGE LEVELS, then each halving of voltage level corresponds to a 6dB redunction in power level (you need to pay particular attention to the capitalized section).

at this point i have to say that i think that i have explained this as best i can. so if someone still isn't following this, then i can't help them and they will have to refer to other sources for further discussion.

Paperw8: If you look at power as a function of voltage and perform the power measurement AS A RATIO OF THE CORRESPONDING VOLTAGE LEVELS, then each halving of voltage level corresponds to a 6dB reduction in power level

Yes, absolutely. But note that each halving of voltage ALSO corresponds to a 6dB reduction in voltage level.

the voltage level is halved at each 3dB increment

I haven't taken the time to follow the parts of the thread that may be behind that statement, but an increment that results in voltage being halved is not in fact a 3db increment, regardless of the wording that may be used to refer to it. It is a 6db increment.

db = 20log(V1/V2) = 10log(P1/P2)

20log(0.5) = -6.02

Best regards,
-- Al