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-   -   lm1875 question? (http://www.diyaudio.com/forums/chip-amps/167521-lm1875-question.html)

tadiam1 26th May 2010 07:01 PM

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

infinia 26th May 2010 07:20 PM

1 Attachment(s)
see attachment for regulator idea

tadiam1 26th May 2010 07:29 PM

re
 
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 (Post 2200031)
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

re
 
tanks all


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