Propeller Head Plaza

Technical and scientific discussion of amps, cables and other topics.

Use this form to submit comments directly to the Asylum moderators for this forum. We're particularly interested in truly outstanding posts that might be added to our FAQs.
You may also use this form to provide feedback or to call attention to messages that may be in violation of our content rules.

You must login to use this feature.

Inmate Login

By default, logging in will set a session cookie that disappears when you close your browser. Clicking on the 'Remember my Moniker & Password' below will cause a permanent 'Login Cookie' to be set.

Moniker/Username: The Name that you picked or by default, your email. Forgot Moniker?	Examples "Rapper", "Bob W", "joe@aol.com".
Password:	Forgot Password?
	Remember my Moniker & Password ( What's this?)

If you don't have an Asylum Account, you can create one by clicking Here.

Our privacy policy can be reviewed by clicking Here.

Inmate Comments

From:
Your Email:
Subject:

Message Comments

Original Message

RE: Yeah ... and... ? LOL

Posted by tomservo on June 26, 2014 at 07:10:00:
Hi
I am not sure what you mean but I can explain without using dB which is a log scale and can be confusing.
As the dB scale is commonly used, maybe explain that would be better.

dB in this use refers to the difference between two things, a 3dB difference is a factor of two in power, 6dB is 4 times, 12dB is 16 times, 20dB is 100 times, 60dB is a million times.

So, if the distortion in an amplifier were -40dB down from the real signal, the THD would be about 1/10,000 the power or level of the desired signal or 1/100 the Voltage level.

-75 dB here means the difference between the two is about 1/30,000,000 the power of the desired signal.

Is that much change audible?
Now this is more complicated because ears are not microphones, what we experience as “audible reality” is FAR more than just the sound pressure reaching ones ears and includes what we see and know as well.

It is the lifetime of hearing that has allowed us to learn to use all the weird things our ears do as a function of angle and height, to create the 3d mental image we experience as reality.
That stuff is usually disconcerting to audiophiles as we know nothing else but that experience and yet it is also well known to audiologists that our ears aren’t “flat” in their frequency response at all and have all kinds of complications.
Hope that helps