lm1875 question?

tadiam1 · 26th May 2010, 07:01 PM

Is correct put an 7818/7918 regulators in the ps of my gainclone?

No need much power...or put in parell an tansistor on 78xx

infinia · 26th May 2010, 07:20 PM

see attachment for regulator idea

tadiam1 · 26th May 2010, 07:29 PM

thanks

AndrewT · 27th May 2010, 12:16 PM

Tadiam,
most chipamps are specified for maximum output current of 3Apk to 7Apk.
This is why they struggle to perform well. I believe the current capability is too low to drive reactive speakers, particularly when the chip gets warm and/or the speaker impedance is low and not efficient.

The 78xx series are limited to 1 to 1.5Apk. That will cripple the performance of the amplifier.

johnr66 · 27th May 2010, 03:16 PM

I don't know why people want to stiff-rail an audio amp PSU. Music is dynamic after all unless you like playing constant sine waves at near clipping.

infinia · 27th May 2010, 03:51 PM

Quote:

Originally Posted by johnr66

I don't know why people want to stiff-rail an audio amp PSU. Music is dynamic after all unless you like playing constant sine waves at near clipping.

Well there are number of reasons for using Vregs.
1) maybe your XFMR voltages are too high.
2) Adapting the rail volts to obtain better chip amp SOA to output impedance ratio. 8-4 ohm switch?
3) Reducing PS ripple.
Usually by using voltage regulation lets one get the last ounce of audio performance from these little chips. Changing the sound of power amps playing near the rails is fun too.

tadiam1 · 27th May 2010, 04:41 PM

tanks all

26th May 2010, 07:01 PM	#1
tadiam1 diyAudio Member Join Date: Dec 2009 Location: argentina	lm1875 question? Is correct put an 7818/7918 regulators in the ps of my gainclone? No need much power...or put in parell an tansistor on 78xx

26th May 2010, 07:29 PM	#3
tadiam1 diyAudio Member Join Date: Dec 2009 Location: argentina	re thanks

27th May 2010, 12:16 PM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Tadiam, most chipamps are specified for maximum output current of 3Apk to 7Apk. This is why they struggle to perform well. I believe the current capability is too low to drive reactive speakers, particularly when the chip gets warm and/or the speaker impedance is low and not efficient. The 78xx series are limited to 1 to 1.5Apk. That will cripple the performance of the amplifier. __________________ regards Andrew T.

27th May 2010, 04:41 PM	#7
tadiam1 diyAudio Member Join Date: Dec 2009 Location: argentina	re tanks all

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27th May 2010, 03:16 PM	#5
johnr66 diyAudio Member Join Date: Mar 2009	I don't know why people want to stiff-rail an audio amp PSU. Music is dynamic after all unless you like playing constant sine waves at near clipping.

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