DiyMobileAudio.com Car Stereo Forum banner
1 - 12 of 12 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter · #1 ·
Okay, so I was recommended this site to learn more about speaker quality and performance. I dont know too much about the technical aspects of speakers. What I want to know is what to look for, especially HOW to read a graph of a speaker. What to look for when I see a graph, and what it all means in terms of a speaker's specific performance. Thank you.

btw...great site you guys, wonderful information you have here.

Big Poppa
 

·
Registered
Joined
·
2,298 Posts
Well the red line in this case is your sensitivity measured in decible (db). It's measured across the frequency range that the graph shows.

The blue line is the impedance of the driver. In this case it looks to be 6 ohms (or somewhere in there). The rise in impedance is normal. As the speaker reaches it's lower frequency limits the impedance starts to peak. The impedance also starts to rise as it starts to extend upward. In this speaker's case, I'd say it will run well between 200-7000 hz. If I were adding this speaker to a 3 way setup, which it looks like it would be well suited for, I'd cross it over (bandpass) at 250hz (highpass) and 5000hz (lowpass). That would be totally preference though, and all the graphs in the world can't tell you how a driver will perform in a car.

I'm guessing this driver is somewhere between 4" and 5 1/4" based on it's frequency response.
 

·
Registered
Joined
·
120 Posts
Big Poppa said:
Thanks and what about this frequency graph? What does this tell me about his particular speaker?

on axis, that speaker preforms best from approx. 200hz to 2khz with a sensitivity around 95db. (top line)
I am not sure what the two lower lines are. I am guessing off axis response, but those dont look like typical off axis graphs. If they are then you defiantly dont want to be using those speakers off axis!
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #8 ·
But what about the graph makes you say that. I would like to learn HOW to read graphs. Do I just look for the peaks in the graph? Is this how I tell if a certain speaker performs well? I know that graphs are a generalization of performance, but it can give certain expectations or foreshadow its performance.
 

·
Registered
Joined
·
32 Posts
If you look at the thing its really self explanitory lol. On the left you have your number in DB (In simple terms this is how loud the speaker is at the givin test range/wattage). On the bottom in the frequency (20-80 is basically subs, 80-200 is midbass, 200-about 5000 is midrange, and above that is what most little tweeters play, these are very rough numbers btw i dont know EXACTLY how its classified but thats somewhere close).

A responce graph can tell you somewhat ow a speaker will perform. In basic terms the goal here is to have the flattest responce you can achieve.Any dips and peaks in that graph is showing that the speaker is louder and quieter at certain frequencies. which we do NOT want unless you are purposley doing this with a proccesor to change the sound to your preference.
The problem with these graphs is that its not measured in a car where you will get relfextion, cancelation, wierd dips and peaks all over the damn place. So whn you drop a speaker or anyting in you car the graph will look extreamly different than the one the manufacturer shows it does. In order to correct these issues in a car we use things as Equalizers, to independently adjust several frequencies to bring the responce flat again. Again the goal here is to have a flat line from 20-20,000 hertz basically.

No if your wondering why these graphs are any good since its different in a car (which you should be), i do not know the answer for sure. But i know the most common use for these is finding the basic idea of the limits of the speaker for mating with crossovers. If the graph shows that a speaker starts dropping from 5k+, that means you will need anothr speaker to play 5k+ becuase the other speaker cannot do it. This is why stereos consist of multiple speakers. If the graph shows that the speaker starts dropping from 300 an below, then you cannot run that speaker any lower than around 250-300 becuase you will blow it when you turn it up to loud. Small speakers dont play Low frequencies, these graphs help you understand the limit of how far down, or high the speaker can play.

Generally we want a speaker to be able to play +or - 3 Db in the area that we wil have it set to playing. So if you want a speaker to play from 300hertz-5000hertz, then you want the graph to not dip or peak more than about 3Db in each direction. Once you get big dips and peaks in each direction you need an EQ (equalizer) to fix it. Now i know i said earlier that this wont matter becuase being in carscrews everything up, but many people modify there cars so that these reflections and things that disrupt the frequency responce dont occur. So if the speaker has a flat repsponce on that manufature measured graphs you have posted, then they wil be damn close in the car when you set everything up right (which can be very very hard and time consuming)

Nowon the off axis an on axis responce. Lower frequncies genreally do not need to be pointed at you. A sub for exaple. You can here it basically everywhere in the car about the same even whenits not pointed at you becuase the wavelengths of the frequency are so large. As you get into higher frequencies such as 500+ the wavelengths get smaller and smaller. So if your speaker is not pointed at you or however it needs to be pointed the get the flat responce te higher frequencies will slowly start rolling down. You generally see this on graphs when there are multiple lines and each has a different color. Example you have a 5 inch midrange that can play 200-8k on axis. Off axis at 15 degrees it might play 200-6k, 30 degrees 200-4k, and its gets lower and lower the more you point off axis.Youll see what i mean when you view the graphs.

Some speakers are purposley designed with these peaks becuase they are meant to drop right into you door very much off axis. This natural boost the speaker has in the upper frequencies gets cut down from being off axis and makes a flatter responce. On axis the speaker will sound horrid unless eq'd, but being off axis cuts down that natural boost the speaker has. So sometimes the grpahs can fool you like that, you must read howthe speaker is designed to be installed before you judge the graphs in many cases.

This is a very rough explanation of how things work i know, so hopefuly more people can refine further what ive said, or correct me if i said anyting wrong.
 

·
Registered
Joined
·
32 Posts
here is an example of a graph showing the speakr on axis and off axis responce. The bright green is on axis, anything below it is off axis. As you can see when you get into the higher frequencies the more off axis you go the faster and steeper the responce rolls off. But in the case of this graph here, you can see even far off axis it is usuable up to 2k. On axis you can go higher that 2k.

 

·
Registered
Joined
·
2,409 Posts
smee said:
A responce graph can tell you somewhat ow a speaker will perform. In basic terms the goal here is to have the flattest responce you can achieve.Any dips and peaks in that graph is showing that the speaker is louder and quieter at certain frequencies.

Again the goal here is to have a flat line from 20-20,000 hertz basically.

But i know the most common use for these is finding the basic idea of the limits of the speaker for mating with crossovers. If the graph shows that a speaker starts dropping from 5k+, that means you will need anothr speaker to play 5k+ becuase the other speaker cannot do it.

these graphs help you understand the limit of how far down, or high the speaker can play.

Generally we want a speaker to be able to play +or - 3 Db in the area that we wil have it set to playing. So if you want a speaker to play from 300hertz-5000hertz, then you want the graph to not dip or peak more than about 3Db in each direction.

So if the speaker has a flat repsponce on that manufature measured graphs you have posted, then they wil be damn close in the car when you set everything up right (which can be very very hard and time consuming)

This is a very rough explanation of how things work i know, so hopefuly more people can refine further what ive said, or correct me if i said anyting wrong.
I think you covered the main points. I definately learned a few things reading your post. Nice job.
 
1 - 12 of 12 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top