Seeking Advice with an Amplifier Design

[yoosefheidari]

hi everyone
i need a good stereo audio ic and power about 5w+5w
i need an ic with high efficiency and good quality.
please intruduce some ic's and i buy one of them.

 

[goldsmith]

hi everyone
i need a good stereo audio ic and power about 5w+5w
i need an ic with high efficiency and good quality.
please intruduce some ic's and i buy one of them.

Hi yoosefheidari

Try TEA2025

Best Wishes
Goldsmith

 

[Audioguru]

The TEA2025 IC does not produce 5W per channel stereo at low distortion. It was made to produce about 1W or less per channel into 8 ohm speakers in portable cassette players (remember them?). With 1W per channel it gets very hot because it is not efficient.

Texas Instruments has 105 mid to high power audio amp ICs and most are class-D with 90% efficiency so they do not need heatsinks.

 

[yoosefheidari]

i need a class ab amplifire
can you introduce me some ic's?

 

[crutschow]

Why does it need to be class AB? They are much less efficient then class D switching amps. The sound quality of a good class D amp is likely undetectable from a class AB by most listeners.

 

[goldsmith]

The TEA2025 IC does not produce 5W per channel stereo at low distortion. It was made to produce about 1W or less per channel into 8 ohm speakers in portable cassette players (remember them?). With 1W per channel it gets very hot because it is not efficient.

Texas Instruments has 105 mid to high power audio amp ICs and most are class-D with 90% efficiency so they do not need heatsinks.

If it be used as a bridge amp ( two of em ) it can easily handle it . doesn't it ?!
BTW : i guess you really Love class D amp ha ha ( either me ) ;-)

Best Luck
Goldsmith

 

[Audioguru]

With a 9V supply when bridged its output is 4.7W into 8 ohms with a massive 10% distortion (clipping like crazy). Its junction is probably far above its maximum allowed temperature of 150 degrees C and adding a heatsink is very difficult (glue one on?). When bridged then its output current is high and the datasheet shows very high distortion when the output current is high (stereo into 4 ohm speakers).

The datasheet for the TEA2025 says it is obsolete.

 

[goldsmith]

With a 9V supply when bridged its output is 4.7W into 8 ohms

Hi again
Who told the load is 8 ohm ? 4 ohm speakers can be used too . isn't it ?

Regarding heat sink , i should say that the datasheet said the IC has an internally thermal protection . and it's supply voltage can be up to 15 volt . you just said 9 but it can be about 15 !


Best Wishes
Goldsmith

 

[D.A.(Tony)Stewart]

Here's a novel design...

Use a 3 terminal linear regulator with good heat sink as a power Amp. to produce 30W/ch if done right.

 

[goldsmith]

Here's a novel design...

Use a 3 terminal linear regulator with good heat sink as a power Amp. to produce 30W/ch if done right.

Oh my G O D ! you have converter an LM317 into an audio amp ? brilliant i've never seen anything like this before . let me confess that you are a very very expert engineer !
Now i've learned this from you . thanks a lot .

Best Regards
Goldsmith

 

[Audioguru]

The LM317 "amplifier" is class-A. Its output transistor produces a pulldown current of only 0.7V/60 ohms= 12mA so the maximum output power is extremely low (0.6mW into 8 ohms).
For 1W RMS into 8 ohms the pulldown current must be 500mA peak. For 1W RMS into 4 ohms the pulldown current must be be 707mA peak.

EDIT: For an output of 30W into 8 ohms the pulldown current must be 2.74A peak then the LM317 must produce a peak current of 5.48A which is impossible from the LM317. The LM317 and the transistor would melt anyway.

 

[D.A.(Tony)Stewart]

Audioguru, I agree with your specs, but the addition of the YT2 and 2 diodes makes the output a Class AB output with active pull-down.

45Vdc with 5V drop on both bipolar (Darlington) drivers with 1.5A limit but using D²PAK RthJC = 3 °C/W which would require aggressive forced air cooling to dump 20W while delivering 30W at 60% efficiency to stay under 90'C,

Speaker impedance was not mentioned but it would be much higher than 8 Ohms. (60?)

But it should do 5W pretty easily. Class D is the way to go forward however. But this is cheap and dirty.

 

[Audioguru]

Audioguru, I agree with your specs, but the addition of the YT2 and 2 diodes makes the output a Class AB output with active pull-down.

I disagree.
VT2, the two diodes and the 60 ohm resistor are a 12mA constant current sink as a load for the LM317 emitter-follower class-A amplifier. The two diodes clamp the base voltage of VT2 so that its current is constant.
A class-AB amplifier has an emitter-follower at the top and another emitter-follower at the bottom, both are driven with the signal.