EEVblog #49 - Decibels (dB's) for Engineers - A Tutorial

Are you a pessimist or an optimist?
Dave explains dB's and how they are useful for us engineering types.

[mrex]

I'm literally 4 classes away from an electrical engineering degree and this video is the first time anyone's ever explained to me what db actually are

[kartikeyak]

13 years old but still helping so many students. I'm so glad i came across your channel!!

[ShizzleMyChizzle]

So passionate about teaching, absolute must watch channel for any electronic engineer.

[selvakumarr]

Wow, I never imagined that I will get so real meaning of dBs. Thank you so much for this.
Recently i came across working with dBs in my profession, I asked many of my friends on what is the real world meaning of dBs, Frankly nobody able to explain anything closer to this. Keep up your wonderful work.

[retrobrw]

I'm so glad I found the EEVBlog. It's such great supplement to my college studies in Electronics Engineering Technology!

[HamedAdefuwa]

dave, ur approach is just genius, everytime I watch your videos I get filled with "dont worry about it, its easy to understand" - all other engineering videos fill me with despair, like I've got to go back and complete 50 physics text books before I can do EE.

[EscapeMCP]

Should have included how to work out dB's inbetween decades e.g.:
20:1 is +6dB for x2 and +20dB for x10 = +26dB
1:50 is -40db for /100 and then +6dB for *2 = -34dB
Such an elegant system. You can always get pretty accurate ballpark figures without any need for calculators.

[aerohk]

Something my professor tried to hide from me.

[eighthourlunch]

Excellent explanation, thank you. I wish my college professors had been as competent at distilling ideas like these into something understandable.

[fuahuahuatime]

Thank you for the video! I learned about dB back in school but never grasped the idea, and it's always been my biggest weakness.

[abberdakas]

Thanks Dave!! Some subjects in class leave me more confused than i was when I started, so I come home and watch your videos and it all becomes clear. Excellent video

[coyohti]

"Because it's nicer when things get more complex."

This video has not only helped me understand dB better but the above quote has helped me understand why my dad (an electrical engineer) was the way he was. 😉

[JennyEverywhere]

If someone wants to really understand logarithms, they should study how to use a slide rule. It gets the concept of logs deep into how you calculate things. There's even dedicated rules designed with radio, electronics, or engineering in mind.

[dylan_king]

this was such a great explanation and your excitement made it really enjoyable. thanks.

[Richard_Broom_Photography]

An excellent video.  Swept away years of misunderstanding.

[kevinchau]

I'm about to graduate from college with an EE degree, I've learned more from your channel than the UofA has taught me.

[HighestRank]

Here's the straight forward equation minus the derpworthy typos and readability issues:
(V.out/V.in)·Log(20)=dB.V.


•Inverse formula:
dB.V/20<10x>=V.out.

dBm/10<10x>=P.out.
•Here is the -3dB. that you hear so much about:
0-3.dBx./20<10x>=0.707<Down by 70.7%>.
0.707Log(20)=0-3dBx.

[forhadahmed]

this man is one of the best teacher on EE on youtube. Hats off

[SmokedTurkey]

Better than my Communication Theory prof's explanation, which took more than 2 classes and I still didn't get it.

Thanks!

[hoofbags]

For some reason, as with quite a few amateur electronics hobbyists, I had a blind spot for dB. As usual, your explanation is hugely helpful. Many thanks. (o: