dephilile
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- Jun 27, 2005
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Hi
On both my JBL amps I have some little dB lights that light up with the music. The louder the music the more of them light up. I have been trying to work out exactly what they are for. Does anyone know?
I’ve come up with the following information after going through some electronics books I have at home.
If you graph the gain of an amplification circuit on log graph paper. Put frequency response on the horizontal axis and decibels on the vertical. This will graph the frequency response of an amp. When the frequency response of an amp is zero decibels it means the frequency that corresponds to that point on the line graph is unfiltered. As the Decibels grow negative then the frequency is slowly filtered.
Ok, so here is what I’m thinking. On my amp I have lights that light up from -15dB to +3dB (picture of what i'm talking bout here http://users.cjb.net/dephililepictures/index.htm) if the +3dB LED lights up does that mean the amp is clipping? It needs to be f***ing loud for that to happen. So does that mean I should tune my setup so that it never passes the 0db LED?
To give you some idea of what the graph I was talking about looks like I tried to recreate something similar to what I found in the text book with text characters. The red “/” and “-“ represent the graph of frequency response.
Ignore any blue zero’s. I had to use them to space things out coz the forum don’t like it when you just use spaces.
BTW, is there some sort of browser setting that needs to be set to upload pictures? I couldn’t upload the picture, I had to chuck it on a website and link to it. i use firefox.
|000000000 /--------------------------- 0db
|000000/
|000/ -20db Decibels
|/
| -40db
|
|
|_____________________________
100001000001000 00010000
frequency
On both my JBL amps I have some little dB lights that light up with the music. The louder the music the more of them light up. I have been trying to work out exactly what they are for. Does anyone know?
I’ve come up with the following information after going through some electronics books I have at home.
If you graph the gain of an amplification circuit on log graph paper. Put frequency response on the horizontal axis and decibels on the vertical. This will graph the frequency response of an amp. When the frequency response of an amp is zero decibels it means the frequency that corresponds to that point on the line graph is unfiltered. As the Decibels grow negative then the frequency is slowly filtered.
Ok, so here is what I’m thinking. On my amp I have lights that light up from -15dB to +3dB (picture of what i'm talking bout here http://users.cjb.net/dephililepictures/index.htm) if the +3dB LED lights up does that mean the amp is clipping? It needs to be f***ing loud for that to happen. So does that mean I should tune my setup so that it never passes the 0db LED?
To give you some idea of what the graph I was talking about looks like I tried to recreate something similar to what I found in the text book with text characters. The red “/” and “-“ represent the graph of frequency response.
Ignore any blue zero’s. I had to use them to space things out coz the forum don’t like it when you just use spaces.
BTW, is there some sort of browser setting that needs to be set to upload pictures? I couldn’t upload the picture, I had to chuck it on a website and link to it. i use firefox.
|000000000 /--------------------------- 0db
|000000/
|000/ -20db Decibels
|/
| -40db
|
|
|_____________________________
100001000001000 00010000
frequency
