Good chip for 5 Watts or so into 8 Ohm?

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Omega_Void

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Joined 2007
#1
I crave the benefit of your advice:

I'd like to build me an amp giving about 5 Watts at least, to 10 Watts maximum, into an 8 ohm speaker.

I want if possible to run it off +/- 15 to 18 Volts for convenience, as the circuit will include some line-level OpAmp circuit also.

TDA2030 looks about the right spec, but I really prefer the National Semi kind of sound to the Thompson chips in general. Strong and warm rather than precise and analytical is the kind of thing I'm hoping for.

Thanks.
 
#3
Thanks for the link, I looked at that one but it seemed higher power than I wanted.

Will LM1875 be okay with +/- 15 Volts? I sort of gather these chips sound quite differently with different supply voltages.

If I give it +/- 25 Volts it'll put out 20W max, which is more than twice my speaker is rated for. That would make me nervous. As well as making the PSU more complex and expensive.

I'll call this chip "Plan B" I think, if nobody proposes anything more exactly fitting...

Thanks.
 
#4
At +/-15V, LM1875 delivers about 10W (from datasheet....), and it is a way better then TDA2030.

The same PSU design will probably work.

A low-wattage speaker should not be a problem, optionally you could place a fuse in series to the speaker.
 
#6
Omega_Void said:
Will LM1875 be okay with +/- 15 Volts? I sort of gather these chips sound quite differently with different supply voltages.
Click to expand...
Yes, it will be fine with ±15 V. You could expect around 9 W into 8 Ohm. Although it would be a pity to waste all that power in a regulated power supply.

Omega_Void said:
If I give it +/- 25 Volts it'll put out 20W max, which is more than twice my speaker is rated for. That would make me nervous. As well as making the PSU more complex and expensive.
Click to expand...
No need to be nervous. The 2x15 V transformer you need for the regulated power supply would, depending on your power supplies layout, give you somewhere between 12 and 13 W into 8 Ohm with an unregulated setup for the amp. Even 20 W will not harm 10 W speakers.

Take into account that 20 W would be the peak output, while your speaker rating is for an average power during a specified amount of time. Even loud listening hardly surpasses an average of 1 W at home. Look at your speaker's efficiency at 1W/1m. Compare that to the fact that an average SPL of 80 dB(A) in industrial environments means in many countries that you are obliged to wear hearing protection. Peaks that may reach the amplifiers nominal output are only present for so short amounts of time, they won't do harm.
 
#8
I have LM1875 amp on +- 16V (2x12V sec; 1.5amp - small tranny; one bridge made of SB560 diods). Sounds just incredible good. LM3785 doesn't sound that good on the same PS.
I also like my TDA2050 amp on the same power supply. Hard to tell which is better (I mean by sound, not by datasheet specs).
 
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