I need help

[dustinpruente]

Im trying to make a monorural (one speaker) meter so that i can meter and detect speaker problems. i hooked the speaker directly up to the meter and it tops out. i tried resistors but they distort the signal. it would be awesome also if i could make a light bar for it. ex: 6 leds, each light up 1-6 as the wattage goes up. can somebody help me because it really sucks having the signal on my left speaker screwed up, thats why i have to meter it.

 

[Klaus]

What you are looking for is a logarithmic meter, VU meters work like that.
Put the resistor in the connection to the meter, not the speaker.
You can use the 3915 LOG LED bar driver chip to make the LED display.
You find suitable circuits for that in the 3914/3915 application notes, try googling for them.
Klaus

 

[dustinpruente]

i have the meter. thanks for the help.

 

[dustinpruente]

One more problem, i got the meter set up and the needle keeps topping out. is there a resistor that will allow realtime frequency changes so that it dosent mess with the signal?

 

[audioguru]

Dust,
A level meter won't tell anything if a speaker has a mechanical problem. Also, if the problem is caused by the amplifier, then you won't know what is a "good" or "bad" meter reading.
Since you have only one speaker that is messed-up, then you probably have another one that is good. Swap the 2 speakers, and if the messed-up problem moves to the other side, then that speaker, not the amplifier, is messed-up. If the problem remains on that same side, then the amplifier or the speaker's wiring (in a car) is messed-up.

 

[Nigel Goodwin]

One more problem, i got the meter set up and the needle keeps topping out. is there a resistor that will allow realtime frequency changes so that it dosent mess with the signal?

A resistor, or two in a potential divider, won't affect the signal in any way, if it is doing you're doing something wrong.

However, I agree with 'audioguru', I don't see what you are hoping to achieve?.

Try giving more details, for a start do you only have the problem with one channel of a stereo system?, if so you have a fault somewhere, and metering the signal to the speaker isn't going to help!.

If you want to build an LED meter, there are loads of examples on the web, try here for a suitable one **broken link removed**.

 

[dustinpruente]

Dust,
A level meter won't tell anything if a speaker has a mechanical problem. Also, if the problem is caused by the amplifier, then you won't know what is a "good" or "bad" meter reading.
Since you have only one speaker that is messed-up, then you probably have another one that is good. Swap the 2 speakers, and if the messed-up problem moves to the other side, then that speaker, not the amplifier, is messed-up. If the problem remains on that same side, then the amplifier or the speaker's wiring (in a car) is messed-up.

Its not about trying to see if a problem is in a mechanical state. Im in the middle of building a 10 channel amplifier for real time surround sound. you have to meter every channel correctly or you could screw it up.

Thanks for the help. ive just about got it.

 

[Nigel Goodwin]

Its not about trying to see if a problem is in a mechanical state. Im in the middle of building a 10 channel amplifier for real time surround sound. you have to meter every channel correctly or you could screw it up.

Interesting idea - but what's 'real time' surround sound?, and where are you going to get a 10 channel surround sound source?.

 

[dustinpruente]

i built a digital processor to change from 5.1 and break it down into 10 diff. channels. maybe ill mass produce 10 channel surround sometime. anyway, i should have worded it different. its not really real time, its real environment. you will actually feel like you are there, there is one drawback, though. you have to have an amp for each channel and they all have to be set EXACTLY the same or it wont sound right. i need the meters to test this.