CDP voltage output...what does it mean to volume?

Through my Pass XP10 inputs 1 and 2 (both balanced inputs) when you switch back and forth, the Parasound is about 6 clicks louder on the volume knob (6 dB?).

@marlin38 Yes, according to the specs and the manual for your preamp 6 clicks corresponds to about 6 db.

My suspicion is that the reason for your findings is that one of the two signals in the balanced signal pair that is being provided by the Theta is not working (i.e., is zero volts). For a given setting of the volume control on the preamp that would result in 6 db less volume than if the Theta was working normally.

If you have a multimeter you could disconnect the Theta from the preamp, play some music with it, and using an AC voltage scale on the meter that is suitable for measuring a few volts measure the voltage between pins 1 and 3 of the Theta’s XLR output connector, and also between pins 1 of 2 of that connector. If my suspicion is correct you’ll most likely see (depending on the internal grounding configuration of the Theta) that the meter indicates a significant voltage for one of those measurements (fluctuating with the music), but zero (or close to it) for the other measurement.

A magnifying glass may be helpful in reading the pin numbers that are marked on the connector.

Regards,
-- Al

Really?  Do you know which models had/have this?  I'm not a McIntosh guy, so the volume of gear they have is bewildering.

marlin38

... how cool would it be if you could preset the volume on your preamp to different levels by input so you could volume match different sources - does that exist?

Oh yes, McIntosh has offered that feature on many of its preamplifiers for years.

I'm hoping to resurrect this thread after being dormant for 13 years.  I too am confused by output voltage from different sources and how it relates to volume.

I have a Parasound D/AC-1600 which states it has an output voltage of 6.0V through the balanced output.  My Theta Pro Gen Va has a stated output of 7.0V through the balanced outputs.  You'd think the volume of the Theta would be "louder" than the Parasound, right?  Well, it's not.

Through my Pass XP10 inputs 1 and 2 (both balanced inputs) when you switch back and forth, the Parasound is about 6 clicks louder on the volume knob (6 dB?).  I've had other DACs hooked to the balanced inputs that were lower output voltage, and they (as expected) were not as loud as the Parasound.  Could the specs be wrong on the Parasound?  Any other explanations?

Sidebar:  how cool would it be if you could preset the volume on your preamp to different levels by input so you could volume match different sources - does that exist?

Here are a couple of more links to sort this out:

Crown amplifiers and dB

Relation ship between dB and perceived volume

This link to Stereophile may help clarify things. On reading through the various posts, I can say that jcmcgrogan2 has got it right. There is something in Gregm's post that might confuse things more...but I'm not sure. I find myself turnig to Wikipedia more and more these days as it is peer review and continuously edited to fairly accurate on most issues...truly an amazing resource enabled by the internet.

cheers,

Bottom line, 10 db SPL doubles the output. 70db is twice as loud as 60 db. 80 db is twice as loud as 70 db. 90 db is twice as loud as 80 db, etc, etc, etc.

No, no Jmc.
As Peak & others note, it is generally accepted that 10dB SPL "SOUNDS" twice as loud (or half, depending how you look at it).

In sound pressure terms (SPL), +6dB is double the sound pressure.
In order to achieve +6dB SPL you need 4x the power.

Also, looking at the formulae Peak's posted, you'll see that 20dB (SPL) is 10x louder (3,16^2).

A difference of 20dB SPL= 10 times "louder" (i.e. sound pressure level). A difference of 40dB SPL= 100 times louder... etc.

Ultimately the confusion stems from the fact that there is a difference between intensity and sound pressure level. You need 4x the intensity (energy/watts) to achieve 2x in spl terms. A difference of 10dB (SPL) is 3,16 times louder... a difference of 20dB (SPL) is roughly 3,16 x 3,16 louder...
You need x10 watts to achieve +10dB of sound pressure... so, 10watts => +10dB spl, 100watts => +20dB spl, 1000w=> +30dB spl (and the speakers have kicked the bucket long ago).
Cheers

This is getting all too confusing.

Bottom line, 10 db SPL doubles the output. 70db is twice as loud as 60 db. 80 db is twice as loud as 70 db. 90 db is twice as loud as 80 db, etc, etc, etc.

Amplifier power, twice the amplifier power will give you 3 db more SPL. So a 200 wpc amp will give you 3 db more output than a 100 wpc amp. So you would approximately need a 1000 wpc amp to create sound twice as loud as a 100 wpc amp.

As for voltages, I'm not sure of the formula, but if indeed twice the voltage gives you 6 db more SPL, then Peak's formula sounds accurate. 6V would sound roughly twice as loud as the standard 2V output. The reason for this is normally so that a preamplifier is not necessary. Since the BAT preamps provide 17 db of gain, your Cary already provides 10 db of gain more than a 2V output, you could easily drive your Pass amps to their full output w/o a preamp.

All this really means is that you have much more gain than you need, and will probably be listening with the volume control turned down pretty low. Careful you don't crank it by accident, you could damage your speakers.

Yes, 6dB is half as loud when you are talking about voltages. If you talk about power, it is 3dB.

Arthur

So something playing 10db less will sound half as loud

Note the phrase "will SOUND half as loud". 6dB SPL is half as loud.

02-19-07: Tboooe
Thanks Peak. So something playing 10db less will sound half as loud? In other words 75db sounds half as loud as 85db?

Correct!

Thanks Peak. So something playing 10db less will sound half as loud? In other words 75db sounds half as loud as 85db?

The formula to determine the differences in dB is
dB = 10* log10(power_ratio)

For voltage it is:
dB =20 * log10(voltage_ratio)

For the 2V system compare to the 6V

dB =20 *log10(2/6) = -9.54 dB

Every 10 dB is 1/10 the power (or about (1/3)**2 ) and will sound about 1/2 as loud. Hope this helps.

I believe the difference between 2v and 6v output is 12db. Thats a quasi educated guess. I do 'know' that the difference between 2v and 4v is 6db so I assumed an equal increase from 4v to 6v. :-)