This may seem like a dumb question, but can any op-amp be used for audio?
I'm currently working on a prototype for my active high-pass filter. Everything was created in Vituixcad 2. (like the image below).
I used the LM311 along with some tantalum capacitors and resistors.
The problem is that there is no audio at all; instead, there is a lot of high-frequency noise.
I'm not sure if I chose the wrong opamp or if the problem is with my wiring.
I'm new at this, and I'm hoping you can help.
Thanks all
I'm currently working on a prototype for my active high-pass filter. Everything was created in Vituixcad 2. (like the image below).
I used the LM311 along with some tantalum capacitors and resistors.
The problem is that there is no audio at all; instead, there is a lot of high-frequency noise.
I'm not sure if I chose the wrong opamp or if the problem is with my wiring.
I'm new at this, and I'm hoping you can help.
Thanks all
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What frequencies are you interested in? that 3 ohm resistor doesn't look right, it's so low value it's probably overloading the preceding stage.
LM311 is a comparator. Use an op-amp like NE5532.
Ed
Ed
When you do an active crossover, you should use much higher values for resistors. This will mean that you also can use much smaller capacitors. Now, to me, it looks like you are trying to re-use some components from a passive crossover. This will not work.
Try resistors values like 1000 ohm (1 k ohm) or maybe 10k ohm and calculate the capacitors values using Vituixcad.
And as someone said - that is not an op-amp. It is a component that you use to build logical circuits. So you must change it for something else. TL-074 or NE5534 perhaps?
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Try resistors values like 1000 ohm (1 k ohm) or maybe 10k ohm and calculate the capacitors values using Vituixcad.
And as someone said - that is not an op-amp. It is a component that you use to build logical circuits. So you must change it for something else. TL-074 or NE5534 perhaps?
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So a quick and dirty high pass filter in Analog designer comes out like this for me.. As you can see, the resistors are way larger than yours. That's necessary so the preceding stage isn't overloaded.
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Yeah
I would add another basic important thing : a speaker needs current ( and voltage: so, power! ) and an audio amplifier should be used to raise the level. Well, the little transistor-radio needs only one bjt to work, and nowadays there are Op-amps that might drive a speaker ( not the LM 386 but ...).
Another hint: the feedback loop! Aren't any designs that use to filter the NFB loop ? Yes, I know there are ( many amplifiers, used to integrate the tone controls in the FB loop, though it might seem risky ) IC based power amplifiers that do that. And also discrete... though they are in the low-fidelity segment, but that's was long time ago, I guess nowadays is all done in the digital domain (EQ, x-over )
probably.
I would add another basic important thing : a speaker needs current ( and voltage: so, power! ) and an audio amplifier should be used to raise the level. Well, the little transistor-radio needs only one bjt to work, and nowadays there are Op-amps that might drive a speaker ( not the LM 386 but ...).
Another hint: the feedback loop! Aren't any designs that use to filter the NFB loop ? Yes, I know there are ( many amplifiers, used to integrate the tone controls in the FB loop, though it might seem risky ) IC based power amplifiers that do that. And also discrete... though they are in the low-fidelity segment, but that's was long time ago, I guess nowadays is all done in the digital domain (EQ, x-over )
I'm not sure if your schematic is accurate, but it shows you are driving the speaker directly with the opamp. That will not work. Typical opamp will drive around 1k although some will go down a bit lower. Your speaker is 8 ohms roughly. You need a power amp between the opamp and speaker.
There are better ones and poor ones. It depends on various factors. But in any case, the external load must be sufficiently high to not overload the opamp output current. Suppose a 10mA output current with +/- 15V this means 15Vpk/10mA = 1.5Kohms. This is a minimum value. Preferable to use the higher you can compatible with the function to be used (some passive filters may need negative capacitors if too high resistances are used) and Johnson noise in them.
1) LM311 is NOT an Op Amp
2) LM311 is OPEN COLLECTOR so it always needs a resistor load from output to +V ; typically 4k7 ... or a lamp/relay coil/etc. , the intended use.
3) LM311 can NOT drive a speaker
4) all your crossover impedances are at least 1000 times too low.
5) sadly, and that is my main beef with simulators, is that they do not have "common sense" or "experience", you put nonsense values in as you did and it happily gives you an answer, such as "4kHz highpass" or whatever you asked, without adding the slightest warning that in practice it will NOT work, as all of us are telling above.
2) LM311 is OPEN COLLECTOR so it always needs a resistor load from output to +V ; typically 4k7 ... or a lamp/relay coil/etc. , the intended use.
3) LM311 can NOT drive a speaker
4) all your crossover impedances are at least 1000 times too low.
5) sadly, and that is my main beef with simulators, is that they do not have "common sense" or "experience", you put nonsense values in as you did and it happily gives you an answer, such as "4kHz highpass" or whatever you asked, without adding the slightest warning that in practice it will NOT work, as all of us are telling above.
Sorry, I was typing when you replied. I was sort of surprised no one had mentioned an opamp can't drive a speaker, but you got there a minute before I did!
Some opamps may drive some speakers. I did a Wien Bridge oscillating at 4KHz that supposedly reject mosquitos, and diretly drive a TV 3x5" 32R speaker at some output volts sufficient to harm myself, from a TLC272 CMOS opamp.
Yah, I mean the LM3886 series are basically big opamps that can drive a speaker
1a) LM311 is a comparator, which means it is not stable with feedback. It is intended to switch between on and off, and not for linear operation.
2a) And pin1 has to be connected, typically to the negative rail. You cannot ignore the equivalent schematic and expect it to work. You have to understand how the chip maker accomplishes their goals and work with or around their choices. Looking at the equivalent schematic, you can predict problems and decide if they are a problem in your application. Such problems may include slew rate, distortion, common mode range, ...
5a) The real problem with simulation is poor simulation models. A classic problem is op-amp models that use internal voltage or current sources and ignore the rail voltages and/or do not model the supply pin currents. I have never seen these problems with LTC models but most 5532 models are trash. The LM3886 model is seriously flawed. This may be deliberate to discourage cheap copies, and better models are provided to authorized users? Note that the Vbe Zener voltage and Vceo of bjts is ignored by default. Simulation references all voltage from "ground", so you cannot simulate a floating circuit.
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Please read the relevant data sheets and application notes before using a particular device.
That's what they are for.
The data sheet says:
The LMx11 operates solely as a voltage comparator, comparing the differential voltage between
the positive and negative pins and outputting a logic low or high impedance (logic high with pullup)
based on the input differential polarity.
Thank you, I actually use a calculator to make a crossover and then put all of the value to Vituixcad and hope it's gonna work. I have learned a lot here
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Thank you for the info, I actually use a tpa3110 as my amplifier