Best Audio Chip For.......

[Space Varmint]

Hey, if Audioguru is around or anybody. Looking for the best alternative for an audio chip to drive a small speaker. I am running the output of a single conversion receiver into a LM386 right now and just does not have quite enough kick for a speaker. Sounds great with head phones and will make your ears bleed but not the case with a speaker. I do not want stereo because I don't want a wasted channel. Just single IN single OUT with a little more umf! than a LM386.

Thanks, SV

 

[Gobbledok]

How about a TDA1905?

 

[Speakerguy]

LM1875 is nice and simple, and a BIG power increase (up to 20W). It's in a TO-220 style package.

 

[Ubergeek63]

if you can handle fine pitch use https://www.electro-tech-online.com/custompdfs/2010/03/tpa2000d1.pdf it has a decent kick (2W into 4 ohms @ 5V) and no power pad to solder down. Plus as a class d it does so at 90% efficiency.

 

[audioguru]

The output at clipping for an LM386 with a 9V supply is only 0.45W into 8 ohms. If the LM386 has a higher supply voltage then its heating increases, not its output power. It drives a 4 ohm speaker poorly with with a high power loss as heat.

Most little speakers are 8 ohms. Cars use 4 ohm speakers.
Twice as loud needs power that is 10 times more. So you probably need 4.5W.

The TDA1905 has an output of 4.5W into 8 ohms at clipping when its supply is its max of 18V.
The LM1875 has an output of 4.5W into 8 ohms at clipping when its supply is about 24V and its idle current is extremely high.
The TPA2000 has an output of only 1.2W into 8 ohms so it won't sound much louder than an LM386.

I would probably use a TDA7240A amplifier IC that produces 4.5W into 8 ohms at clipping with a 10V supply.

 

[Space Varmint]

These look great! Thanks guys (thumbs up symbol goes here)

 

[Ubergeek63]

The output at clipping for an LM386 with a 9V supply is only 0.45W into 8 ohms. If the LM386 has a higher supply voltage then its heating increases, not its output power. It drives a 4 ohm speaker poorly with with a high power loss as heat.

Most little speakers are 8 ohms. Cars use 4 ohm speakers.
Twice as loud needs power that is 10 times more. So you probably need 4.5W.

The TDA1905 has an output of 4.5W into 8 ohms at clipping when its supply is its max of 18V.
The LM1875 has an output of 4.5W into 8 ohms at clipping when its supply is about 24V and its idle current is extremely high.
The TPA2000 has an output of only 1.2W into 8 ohms so it won't sound much louder than an LM386.

I would probably use a TDA7240A amplifier IC that produces 4.5W into 8 ohms at clipping with a 10V supply.

Not true ... BEWARE SPECMANSHIP!!!!!

the most power that you can get out of an LM386 into 8Ω is 0.7W at 12V per the data sheet.

I=√P/R=√0.7/8=0.3A RMS

multiply by 12V and divide by 2 since it is only drawing on the positive half of the cycle:

0.3A*12V/2=1.8W

minus the power delivered to the load: 1.8W-0.7W=1.1W

multiply by thermal resistance (107 best case case) and add ambient: 1.1W*107C/W+50C (in the summer) =170C with a 150C max junction temp.

that is assuming you are using a DIP package, the others are 172C/W and 210C/W

At 5V the LM386 only puts out 0.25W into 8Ω and the OP did not state his power rail voltage or speaker type (and still has not done so)

Dan

 

[audioguru]

Not true ... BEWARE SPECMANSHIP!!!!!

the most power that you can get out of an LM386 into 8Ω is 0.7W at 12V per the data sheet.

No.
The output power is not spec'd when the supply is 12V but a graph is shown where its output into 8 ohms is 6.5V p-p.
6.5V p-p is 2.3V RMS. Then the power into 8 ohms at a horrible-sounding 10% distortion is 2.3 squared/8= 0.66W and the output at clipping is 0.66W x 0.8= 0.53W, not 0.7W.

At 5V the LM386 only puts out 0.25W into 8Ω

No.
With a 6V supply the distortion graph shows it clipping at only 200mW.
With a 5V supply its output into 8 ohms is shown on a graph at 3V p-p which is 1.06V RMS which is an output of 141mW with a horrible-sounding 10% distortion. It is only 113mW at clipping, not 250mW.

 

[Ubergeek63]

No.
With a 6V supply the distortion graph shows it clipping at only 200mW.
With a 5V supply its output into 8 ohms is shown on a graph at 3V p-p which is 1.06V RMS which is an output of 141mW with a horrible-sounding 10% distortion. It is only 113mW at clipping, not 250mW.

Audio, Audio, Audio...

You can't have it both ways. I was trying to be fair, and you are refusing!

On equal footing then he SHOULD use the TPA2000 if he is at 5V or so since by your own admission the LM386 is only good for 150mW and the TPA2000 puts 1W into 8 ohms at 5V for 0.1%THD

Dan

 

[Ubergeek63]

No.
The output power is not spec'd when the supply is 12V but a graph is shown where its output into 8 ohms is 6.5V p-p.
6.5V p-p is 2.3V RMS. Then the power into 8 ohms at a horrible-sounding 10% distortion is 2.3 squared/8= 0.66W and the output at clipping is 0.66W x 0.8= 0.53W, not 0.7W.

check the data sheet - i did not bother with the calculation, 0.7W is right off the sheet

 

[Space Varmint]

Not true ... BEWARE SPECMANSHIP!!!!!

the most power that you can get out of an LM386 into 8Ω is 0.7W at 12V per the data sheet.

I=√P/R=√0.7/8=0.3A RMS

multiply by 12V and divide by 2 since it is only drawing on the positive half of the cycle:

0.3A*12V/2=1.8W

minus the power delivered to the load: 1.8W-0.7W=1.1W

multiply by thermal resistance (107 best case case) and add ambient: 1.1W*107C/W+50C (in the summer) =170C with a 150C max junction temp.

that is assuming you are using a DIP package, the others are 172C/W and 210C/W

At 5V the LM386 only puts out 0.25W into 8Ω and the OP did not state his power rail voltage or speaker type (and still has not done so)

Dan

Yeah that's right. I have heard or read that somewhere. (.7 watts). Sorry, I am using 6 volts so I'm stuck with head phones this go round. Will pull down some data sheets today.

 

[Ubergeek63]

Yeah that's right. I have heard or read that somewhere. (.7 watts). Sorry, I am using 6 volts so I'm stuck with head phones this go round. Will pull down some data sheets today.

like i was saying to Audio: TPA2000 gives 1W @ 0.1%THD into 8 ohms @ 5V

 

[Space Varmint]

like i was saying to Audio: TPA2000 gives 1W @ 0.1%THD into 8 ohms @ 5V

That sounds lie a good one there. You think 1 watt is ample audio? You know, lie some cheap toy. I might need 2 watts for shortwave since most signal are not that strong like local broadcast.

 

[Ubergeek63]

That sounds lie a good one there. You think 1 watt is ample audio? You know, lie some cheap toy. I might need 2 watts for shortwave since most signal are not that strong like local broadcast.

that has nothing to do with it. signal strength effects reception

the audio gain and max audio level are not linked together. ... see that little knob over there? turn it clockwise

dan

 

[audioguru]

Yes Space Varmint,
You are confusing the voltage gain of an amplifier and actually the voltage gain of the entire radio with the max power an amplifier can produce in a speaker. A cheap clock radio has an output power at clipping of 0.5W to 1W.

I souped up my clock radio with an LM390 bootstrapped amplfier IC that has an output at clipping of 1.0W into 8 ohms with a 9V supply.

Yes Dan,
The TPA2000 has an output of only 1W and it cannot use a higher supply voltage. An ordinary TDA2822M is in a DIP-8 case and also produces an output at clipping of 1W into 8 ohms but with a 6V supply.

1W is not much volume from a cheap little speaker. 4.5W will be noticeably louder.

 

[Space Varmint]

that has nothing to do with it. signal strength effects reception

the audio gain and max audio level are not linked together. ... see that little knob over there? turn it clockwise

dan

Oh brother. Here it comes. Yes I know some radio. I know that single conversion does not give much IF strength. But the audio can do more, hopefully without feedback.

 

[Space Varmint]

Yes Space Varmint,
You are confusing the voltage gain of an amplifier and actually the voltage gain of the entire radio with the max power an amplifier can produce in a speaker. A cheap clock radio has an output power at clipping of 0.5W to 1W.

I souped up my clock radio with an LM390 bootstrapped amplfier IC that has an output at clipping of 1.0W into 8 ohms with a 9V supply.

Yes Dan,
The TPA2000 has an output of only 1W and it cannot use a higher supply voltage. An ordinary TDA2822M is in a DIP-8 case and also produces an output at clipping of 1W into 8 ohms but with a 6V supply.

1W is not much volume from a cheap little speaker. 4.5W will be noticeably louder.

See? That's what I'm talking about. So what would give me 4.5 watts? I might get some feedback...right?

 

[audioguru]

Your LM386 amp produces 0.45W max when it has a 9V supply. When its gain is set to 20 then an audio input of 106mV lets it produce max output.
A 4.5W amplifier can also be set with a gain of 20 so its output will also be at 0.45W when its input is 106mV.
Both amplifiers will be exactly the same.

But only when the input signal is higher then the amplifier with more max output power will sound louder.
With weak signals they will sound exactly the same.

Your radios do not have enough RF gain. The output level from an AM radio is determined by the amplitude of the signal. When the signal is strong then the output level is high. When the signal is weak then the radio's AGC sets the gain to max but if there is not enough gain then the output level will be low. Max output power has nothing to do with an amplifier's gain.


Feedback? Acousical feedback howling or whistling is caused when a microphone can hear the speaker that its amplifier is driving. I don't think your radio has a microphone so it won't have acoustical feedback.

 

[Space Varmint]

Your LM386 amp produces 0.45W max when it has a 9V supply. When its gain is set to 20 then an audio input of 106mV lets it produce max output.
A 4.5W amplifier can also be set with a gain of 20 so its output will also be at 0.45W when its input is 106mV.
Both amplifiers will be exactly the same.

But only when the input signal is higher then the amplifier with more max output power will sound louder.
With weak signals they will sound exactly the same.

Your radios do not have enough RF gain. The output level from an AM radio is determined by the amplitude of the signal. When the signal is strong then the output level is high. When the signal is weak then the radio's AGC sets the gain to max but if there is not enough gain then the output level will be low. Max output power has nothing to do with an amplifier's gain.


Feedback? Acousical feedback howling or whistling is caused when a microphone can hear the speaker that its amplifier is driving. I don't think your radio has a microphone so it won't have acoustical feedback.

Oh, so you are saying that if your audio gain is too high and the input is not substantial, then there is no way to have feedback unless you have a microphone? Better think that through. There are numerous paths for feedback, one being the power buss. You are right that my AGC is set low because I have no shielding. I'm trying to put all in one box which is done. I just want more audio.

 

[Nigel Goodwin]

Oh, so you are saying that if your audio gain is too high and the input is not substantial, then there is no way to have feedback unless you have a microphone? Better think that through. There are numerous paths for feedback, one being the power buss. You are right that my AGC is set low because I have no shielding. I'm trying to put all in one box which is done. I just want more audio.

If you get feedback in that way, then it's because your design is completely useless - it's absolutely impossible in anything like a correct design.