need volume booster schematic

[prorms]

need a schematic for volume booster
not just regular volume one that use an opamp
one that doesnt add distortion

 

[jaycee]

I'm guessing what you really mean here is that you want a circuit for an audio compressor, as they use on TV commercials to make them sound 5 times louder than the program you're watching!

 

[anatech]

Hi prorms,
Would you please clarify your needs?

An idea of available power supply may come in handy too.

The only thing I understand from your post is that you don't seem to like op amps and that you think they all add distortion.

-Chris

 

[prorms]

i every time i build volume werer need to increase the output
alot of the time i get distortion wondering what would be a good
design to work with

example 25mV to to 8v

 

[anatech]

Hi prorms,
Alright then, what power supply voltages are available to use? What type of system are you working on?

example 25mV to to 8v

25 mV is high and 8 V isn't really a signal level. It's higher.

What are you trying to do?

-Chris

 

[prorms]

+ 7 v
-7 v
i can always change the voltage

 

[jaycee]

you want 8V swings with a 7v supply? no wonder it's distorting - it's probably clipping at around 4-5v.

 

[prorms]

what would be a good way get out of this problem

 

[davidallancole]

More voltage.

 

[prorms]

what would be a good opamp design to use that will not cause distortion????

also is thier ant way to stop clipping beside increase power supply???

 

[anatech]

Hi prorms,

also is thier ant way to stop clipping beside increase power supply???

When you are out of volts, you are out of volts. It's as simple as that. You could use a step up transformer, but that's another can of worms.

what would be a good opamp design to use that will not cause distortion????

Firstly, compared to what?? A 741? Sure, almost any op amp will do that. NE5532A's sound good. You also have to understand that the circuit depends on your layout and assembly abilities to sound good.

It sounds like you need to do some reading before you start anything.

-Chris

 

[prorms]

does NE5532A need a capacitor between pin 1 and 8 22pf??
http://focus.ti.com/lit/ds/symlink/ne5534.pdf
and the 741 dont???

 

[anatech]

Hi prorms,

does NE5532A need a capacitor between pin 1 and 8 22pf??

? New one on me. It's unity gain stable.

Ah ha! You are looking at the NE5534A, and it is not unity gain stable out of the box. SO for the NE5534A - Yes! You do need to add compensation.

-Chris

 

[prorms]

this type of schematic???????

unity gain stable

 

[prorms]

....

 

[gootee]

http://www.national.com/an/AN/AN-20.pdf

http://www.national.com/an/AN/AN-31.pdf

 

[anatech]

Hi prorms,
gootee has just given you a couple old but good app. notes. You should be able to find some ideas in there. I doubt you want to use an op amp at unity gain if you want some gain. It will simply behave better when it's unity gain stable. Easier for beginners.

Please, what exactly are you try to do?

-Chris

 

[prorms]

clear up
5% distortion

 

[gootee]

what would be a good opamp design to use that will not cause distortion????

also is thier ant way to stop clipping beside increase power supply???

Hi prorms,

You are not giving enough information for anyone to be able to give you a specific solution, or even be able to easily point you in the right direction. For example, what is the signal source? What is its maximum output voltage swing? And what are you driving, with this "booster"? And what is the maximum voltage swing that it can accept at its input? Knowing their impedances would br very helpful, too.

Without any specific information, I can only speak in generalities, which might make it more tedious than necessary to try to help you:

To do this right, even assuming the most-favorable impedances, you have to know the maximum possible voltage swing (i.e. maximum peak-to-peak or zero-to-peak signal voltages) of whatever is supplying the input signal for the amplifier we're discussing, that you want to construct. And you have to know the maximum voltage swing that can be accepted by whatever the amplifier's output will be driving.

If the input signal source's maximum output voltage is fixed, i.e. cannot be changed, then just assume the maximum signal level it can produce.

Then, the gain of this new amplifier multiplied by its peak input signal level cannot exceed the maximum acceptable level for the input of whatever this amplifier's output will be driving. If it does, probably either the driven unit will be damaged, or, the signal might "clip", i.e. have its peaks shaved off, probably at whatever level the power supply limits the voltage swing to (which will usually be at least a volt or two below the power supply voltage), in whatever this amplifier is driving. Clipping causes distortion; often major distortion.

Another way to get clipping (and distortion) is if this new amplifier's gain multiplied by the maximum input signal level is greater that the voltage to which its opamp can swing, which might be because either the power supply voltages are too low, or the gain is too high.

Many opamps cannot swing closer than 1.5v to 2.5v from the power supply voltages. So, for example, if you want your amplifier's output signal to swing +/-5 volts max, it would be wise to have power supply voltages of at least, or more than, +/-7.5 volts. (And, for many opamps, it's best to use a lot higher power supply voltage than you actually need, to get the lowest distortion (as long as you don't exceed the max power supply voltages specified in the opamp's datasheet, of course). )

Another possibility is that your input level is really tiny and your output level needs to be quite high. If you need a gain of, say, 100X, you can usually get less distortion by using two 10X amplifiers, in series, i.e. one after the other, instead of one 100X amp.

As long as you're SURE that you wouldn't exceed the driven unit's maximum acceptable input voltage, you could just make a simple opamp amplifier, and use a potentiometer (probably with also a small resistor in series with it) in place of one of the two gain-setting resistors, and vary the pot (and thus the gain) until you get a high-enough output voltage, but no clipping or distortion.

You should definitely download the datasheet for whatever opamp you're planning to use, and study it.

Good luck.

- Tom Gootee

http://www.fullnet.com/~tomg/index.html

 

[prorms]

here is the start of preamp were gain is
if need the reset let me know