Hello,
I am using Dynamic Balanced Microphone with MAX4063 as preamplifier with a maximum gain of 46dB.I need futher amplification to get to the signal to line level.
Can anyone suggest the cascading stage to this IC for further amplification of signal from MIC level to Line Level audio signals.
Suneetha.V
I am using Dynamic Balanced Microphone with MAX4063 as preamplifier with a maximum gain of 46dB.I need futher amplification to get to the signal to line level.
Can anyone suggest the cascading stage to this IC for further amplification of signal from MIC level to Line Level audio signals.
Suneetha.V
Just as a thought, I'd use an NE5532 set for a gain of 20. The MAX4063 specs already state a gain of 20, so total gain would be 400, which would I guess get you to something approaching line level.
OR use both sides of an NE5532, both set to a gain of 20, which would be a gain of 400, times the gain of the MAX4063 = gain of 8,000, which would run your car.
OR use both sides of an NE5532, both set to a gain of 20, which would be a gain of 400, times the gain of the MAX4063 = gain of 8,000, which would run your car.
Why are you using a Max4063?
What power supply are you using?
What kind of sound do you want to pick up?
Don't answer just "voice".... specify whether it's somebody whispering 10 meters away or a Rock singer blasting into a microphone pressed into his lips or anything in between.
It's not suitable for line level signals anyway.
Max output I would use is 200 mV RMS, just to have reasonable headroom.
What power supply are you using?
What kind of sound do you want to pick up?
Don't answer just "voice".... specify whether it's somebody whispering 10 meters away or a Rock singer blasting into a microphone pressed into his lips or anything in between.
It's not suitable for line level signals anyway.
Max output I would use is 200 mV RMS, just to have reasonable headroom.
Hi,
Can any one give gain calculations of how much gain is required for microphone preamplifier for a dynamic microphone having sensitivity of 2.2mV/Pa for general announcements in trains,so that I get the +4dbu line level signal?
It's not that complicated really. You mainly need to do some level ballparking.
1 Pa = 94 dB SPL. Singers can reach >110 dB or even >120 dB directly at a mic, but I guess an announcement would take place at a larger distance. It still needs to get over ambient noise though, which even with a directional mic and a ~100 Hz highpass (both highly recommended) could approach 60..70 dB or so. So let's go with a 94 dB target level for the sake of simplicity - it doesn't seem too bad a ballpark figure, and assuming a +20 dBu maximum output level, would give you headroom up to 110 dB. Input dynamic range handling could be increased further by including an ALC/AGC (actually I think this is virtually a must for good intelligibility, but do make sure that the AGC knee still is well above ambient noise).
2.2 mV / Pa, or -53 dBV / Pa... sounds like a dynamic mic, right?
So let's say we want +4 dBu of output for 94 dB SPL. That means we need a total gain of 20 log (1.228 V / 2.2 mV) = 55 dB. If you still want full output at 85 dB, maximum gain should be about 64 dB. So I'd give the MAX 34 dB and the AGC amp up to 30 dB.
Hmm, the MAX is a 5 V part. (Output voltage swing even on 3 V would be more than sufficient for +4 dBu output though.) And it looks like it's intended for electret mics, for dynamic ones noise would be a tad on the high side. So I guess your mic is an electret? Do you intend to be using the bias output? If so, you should determine what sort of levels the microphone will still accept at the given bias voltage. It makes little sense to have the mic go into limiting well before the chain behind it does.
1 Pa = 94 dB SPL. Singers can reach >110 dB or even >120 dB directly at a mic, but I guess an announcement would take place at a larger distance. It still needs to get over ambient noise though, which even with a directional mic and a ~100 Hz highpass (both highly recommended) could approach 60..70 dB or so. So let's go with a 94 dB target level for the sake of simplicity - it doesn't seem too bad a ballpark figure, and assuming a +20 dBu maximum output level, would give you headroom up to 110 dB. Input dynamic range handling could be increased further by including an ALC/AGC (actually I think this is virtually a must for good intelligibility, but do make sure that the AGC knee still is well above ambient noise).
2.2 mV / Pa, or -53 dBV / Pa... sounds like a dynamic mic, right?
So let's say we want +4 dBu of output for 94 dB SPL. That means we need a total gain of 20 log (1.228 V / 2.2 mV) = 55 dB. If you still want full output at 85 dB, maximum gain should be about 64 dB. So I'd give the MAX 34 dB and the AGC amp up to 30 dB.
Hmm, the MAX is a 5 V part. (Output voltage swing even on 3 V would be more than sufficient for +4 dBu output though.) And it looks like it's intended for electret mics, for dynamic ones noise would be a tad on the high side. So I guess your mic is an electret? Do you intend to be using the bias output? If so, you should determine what sort of levels the microphone will still accept at the given bias voltage. It makes little sense to have the mic go into limiting well before the chain behind it does.
Now we are talking Real World application.
And an incredibly noisy background one, so slight almost inaudible hiss will be of no consequence at all.
To begin with, forget Max4063 which is an excellent mic preamp ... if all you have is:
meaning cellphones and similar low voltage battery powered uses and which makes it impossible to get the line level signal you want.
At most -10dB when you ask for +4
Unless you are 15 to 200 meters away from the preamp , you don't even need a balanced input, go figure, even if your microphone is balanced.
If you have +/-15V available or , say, +24V or at least +12V , use just a TL072 .
First stage fixed gain, say 50X ; then 10K log (audio) to 100K log volume control, and another 20 to 50X gain stage, easily driving those +4dB .
In the first stage you can add a trimmer pot or 2 or 3 switch selectable gain resistors to optimize gain.
All theoretical calculations don't mean much if we don't know how loud and how close will the speaker be.
So the first time you make him speak like he will ever do, both in volume and distance, and you adjust bthe first stage gain so the volume control works roughly in the middle part (say between 3 and 7) .
If you consistently need to use it on 8 to 10, increase the gain of the first stage; if always on 1 or 2, decrease gain.
If you decide to make it so, I can suggest a practical circuit with real values.
And if for any reason you really need balanced inputs, that can be settled to.
Extra detail: cut lows, at least below 100Hz and maybe as much as below 250Hz, acoustics in Bus and Train stations are HORRIBLE.
You'll also need a distributed speaker system, so nobody is very far from one.
Or, if you mean a PA system inside train cars, that can also be accomodated.
Or is it a rolling system?
Mounted on a small hand pushed rolling cart?
Battery powered?
Every situation has a different solution.
Now we are talking Real World application.
And an incredibly noisy background one, so slight almost inaudible hiss will be of no consequence at all.
To begin with, forget Max4063 which is an excellent mic preamp ... if all you have is: meaning cellphones and similar low voltage battery powered uses and which makes it impossible to get the line level signal you want.
At most -10dB when you ask for +4
Unless you are 15 to 200 meters away from the preamp , you don't even need a balanced input, go figure, even if your microphone is balanced.
If you have +/-15V available or , say, +24V or at least +12V , use just a TL072 .
First stage fixed gain, say 50X ; then 10K log (audio) to 100K log volume control, and another 20 to 50X gain stage, easily driving those +4dB .
In the first stage you can add a trimmer pot or 2 or 3 switch selectable gain resistors to optimize gain.
All theoretical calculations don't mean much if we don't know how loud and how close will the speaker be.
So the first time you make him speak like he will ever do, both in volume and distance, and you adjust bthe first stage gain so the volume control works roughly in the middle part (say between 3 and 7) .
If you consistently need to use it on 8 to 10, increase the gain of the first stage; if always on 1 or 2, decrease gain.
If you decide to make it so, I can suggest a practical circuit with real values.
And if for any reason you really need balanced inputs, that can be settled to.
Extra detail: cut lows, at least below 100Hz and maybe as much as below 250Hz, acoustics in Bus and Train stations are HORRIBLE.
You'll also need a distributed speaker system, so nobody is very far from one.
Or, if you mean a PA system inside train cars, that can also be accomodated.
Or is it a rolling system?
Mounted on a small hand pushed rolling cart?
Battery powered?
Every situation has a different solution.
Now we are talking Real World application.
And an incredibly noisy background one, so slight almost inaudible hiss will be of no consequence at all.
To begin with, forget Max4063 which is an excellent mic preamp ... if all you have is: meaning cellphones and similar low voltage battery powered uses and which makes it impossible to get the line level signal you want.
At most -10dB when you ask for +4
Unless you are 15 to 200 meters away from the preamp , you don't even need a balanced input, go figure, even if your microphone is balanced.
If you have +/-15V available or , say, +24V or at least +12V , use just a TL072 .
First stage fixed gain, say 50X ; then 10K log (audio) to 100K log volume control, and another 20 to 50X gain stage, easily driving those +4dB .
In the first stage you can add a trimmer pot or 2 or 3 switch selectable gain resistors to optimize gain.
All theoretical calculations don't mean much if we don't know how loud and how close will the speaker be.
So the first time you make him speak like he will ever do, both in volume and distance, and you adjust bthe first stage gain so the volume control works roughly in the middle part (say between 3 and 7) .
If you consistently need to use it on 8 to 10, increase the gain of the first stage; if always on 1 or 2, decrease gain.
If you decide to make it so, I can suggest a practical circuit with real values.
And if for any reason you really need balanced inputs, that can be settled to.
Extra detail: cut lows, at least below 100Hz and maybe as much as below 250Hz, acoustics in Bus and Train stations are HORRIBLE.
You'll also need a distributed speaker system, so nobody is very far from one.
Or, if you mean a PA system inside train cars, that can also be accomodated.
Or is it a rolling system?
Mounted on a small hand pushed rolling cart?
Battery powered?
Every situation has a different solution.
Hello JMFahey,
Our system is working on 5V only.no split supplies and high voltages.I tested the ckt with 5V Supply with Ahuja AGN-500 balanced microphone using MAX4063.If I need further amplification can I use a transistor ckt or increase the gain at Power amplifier stage?
It would be difficult to do anything on the input side without compromising CMRR. You could try looking for a balanced, rail-rail output differential opamp for the output side, or make up one of your own using two conventional rail-rail output opamps in the first stage of an instrumentation amplifier. (I very much assume that the latter option would require much less exotic parts while getting the job done just the same.)
And to repeat, both a highpass and an ALC are highly recommended. The highpass should come no later than after the MAX in order to avoid amplfying useless rumble that could clip later stages. A hang-type AGC / ALC (in about the same place or unified with the post-amplifier) is very useful because speaking volumes can differ quite a bit and train PA systems often have very little dynamic range to work with in between ambient noise and the mechanical limits of the smallish speaker drivers used. All such circuits I've come across so far have been unbalanced though.
(ALC vs. AGC is more of a terminology difference than anything else. If it's affecting audio, it's typically called ALC, while at IF or RF you'd find AGC instead. Underlying principles are the same, however, and you'll find a lot more theoretical discussion among RF folks, yours truly actually included.)
And to repeat, both a highpass and an ALC are highly recommended. The highpass should come no later than after the MAX in order to avoid amplfying useless rumble that could clip later stages. A hang-type AGC / ALC (in about the same place or unified with the post-amplifier) is very useful because speaking volumes can differ quite a bit and train PA systems often have very little dynamic range to work with in between ambient noise and the mechanical limits of the smallish speaker drivers used. All such circuits I've come across so far have been unbalanced though.
(ALC vs. AGC is more of a terminology difference than anything else. If it's affecting audio, it's typically called ALC, while at IF or RF you'd find AGC instead. Underlying principles are the same, however, and you'll find a lot more theoretical discussion among RF folks, yours truly actually included.)
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