Stupid? Question!

[Cal Blacksmith]

Ok, I am an old fart. There was a time when the gain on an amp or reciever had numbers next to the dial (if there were numbers at all) they went from 1 to 10 clockwise. Our new Yamaha Rs-v750 reciever uses -DB to indicat the level. The question is, What is this in reference to? With a dial that goes from 1 to 10, 2 is louder than 1 and less loud than 3 but WHAT THE %^$&%$^ IS -25DB referenced to??????

[Ray Garrison]

Generally speaking, no telling. In an ideal world, the volume scale would be referenced to some standard load, and calibrated such that 0dB (that is, no attenuation) would represent the maximum available output level without clipping. And, each 6dB decrease (say, from -10dB to -16dB) would represent a 50% reduction in output level.

However, every speaker represents a different impedence and sensitivity, such that that 0dB rating, even if it were carefully and accurately calibrated to some standard load, would only be accurate into that specific load. Into a more difficult load, the amp would clip before you turned it to the zero dB level. Into a more benign load, it might be able to push more power into a load past the zero dB reference.

About all you can assume is that "further minus" you go, the lower the output level.

Mostly, the dB scales on volume controls are there because someone in marketing thought it looked cool, with the exception of pro stuff or companies like Macintosh.

[Cal Blacksmith]

Thanks! I kinda thought that but wasn't sure. FREEKING marketing people! Something as simpe as a volume dial and they couldn't leave it alone

[Mighty Favog]

I'm trying to think of something funny to do to the power switch that coincide with the same genre but it just isn't coming to mind right now.

[picky]

Ray pretty much took the words right out of my mouth (great explanation Ray).

In the "real world" (whatever that is?) we, as humans, have hearing that requires approximately a 3 decibel (db) change in volume level (either up or down) before we actually notice a change in that volume. Now, that is on average for the majority as there are of course some individuals with more sensitive hearing than that.

If you look at one of the "0, 1, 2, 3,... to 10" volume controls, "5" gives one the perception that this means the volume is half way up, or at 50%. This is not so. But, the way this really works is logarithmic, making, the - and + db graduated volume control a closer approximation to the truth.

Here is a simple rule of thumb: I we humans require a change of at least 3 db in order to tell that something is louder or more quiet, also consider that if increasing the volume 3 db to hear a increase in volume, it will take twice an much amplifer power to do so. Hence:

These are PURLY hypothetical!!!

1-10 Volume Sound level in room Amplifier output power (In Watts)

Control setting

1 70 db .5 watts

2 73 db (slighty louder) 1.0

3 76 db (louder) 2.0

4 79 db 4.0

5 82 db 8.0

6 85 db 16.0

7 88db 32.0

8 91 db 64.0

9 94 db 128.0 watts

10 97 db 256.0 watts

and so on.....

If this were representative of a 250 watt power amp, the scale above would indicate that the #9 volume setting is actually half way up instead of #5!

I hope I have not confused you more.

[Cal Blacksmith]

No I understand the logrymthic scale of db and watts. No problem there. It is just as I get nearer to that 50 year mark (I'm not kissing it yet but there is some hot breath action!) I rember the way things were when I learned about this stuff and it seems that there is change just for the sake of change. BTW, most any amp I have had started to clip at about the number 7, so 10 never really was used anyway. I also guess that the -db scale makes more sense but on another note, why did they ever had to put electricty in cars? Things were just fine with lanterns on the fenders

[LarryC]

Aren't volume controls also sometimes "tapered," i.e., a steeper volume change in some part of the rotation, usually near the maximum? That would allow smaller, more finely graded volume changes at the low end of the rotation. When I got my 23-step VC preamp, I had a choice of locating the big changes per step at the top or the bottom of the rotation, and I chose the top, to keep the small changes per step at the bottom.

Larry

[Klewless]

My new receiver has the negative numbers for volume setting. Regardless of the type or direction (+/-), these are only reference points.

I don't know or care what the absolute level these numbers represent.

But I do love the ability to return to a previous setting using those reference numbers.

I also do not know whether my receiver uses the audio taper on the volume control. Chances are it does since I think that is pretty standard now (it used to be standary anyway).

[D-MAN]

Good point. In theory, the zero indicates that there is zero attenuation being applied; the amplified output is at maximum.

I had a Crown preamp that had an attenuator volume dial which had 0 in the middle so it was marked off in negative and positive values on either side of the zero mark. What this meant I have no idea...

DM

[Griffinator]

-25dB is referencing maximum input gain. 0dB on a receiver is the receiver slamming out whatever's put into it at maximum power. There are receivers that will allow you to exceed 0dB, but they're basically overdriving the amps to do that.