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Post by vmedchagr on May 10, 2012 11:21:54 GMT
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Deleted
Deleted Member
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Post by Deleted on May 10, 2012 18:40:14 GMT
Some (meaningless ?) background info on this amp for those interested.
It is designed around a chip that is intended for portable gear and specified for 8, 16 and 32 Ohm headphones. It can work on 3V to 5V power supplies (max 5.5V)
The board itself can run between 8V and 24V because of the LM317 that is set to around 5V.
The specs are: freq range (-3dB) 50 Hz to 600kHz presumably at 8Ohm load. With a 32 Ohm load this will be around 10Hz to 600kHz. This can be extended lower by increasing the value of the output caps (originally 470uF) to 1000 or 2200uF (10V rating minimum) and by increasing the value of the (1uF) input caps to higher values (say 3.3uF)
The distortion is given as 0.02% @ 1kHz with a 32 Ohm load and at 75mW output. This looks like a nice figure and around 1kHz our hearing is most sensitive for distortion (roughly between 300Hz and 3kHz) This chip, however, has considerable higher amounts of distortion within the audible band (20Hz to 20kHz) and can even reach 0.3%. To most this will be bordering on being audible so just like the PA2V2 (3V supply) it can sound quite good to seriously good.
The gain can be set at 3x or 6x (10dB or 16dB) The input impedance is 1.7k or 3k3 depending on the gain setting so should be enough to be driven from portable gear. From CDP it is already on the low side of things but can be used.
It is intended for use with 8 to 32 Ohm speakers/headphones. The output resistance is around 0 Ohm.
max output powers for the most common headphones (with 10% distortion) and is determined by the maximum output voltage which is 1.6V:
8 Ohm (very rare): 200mW 16 Ohm = 150mW 32 Ohm = 80mW 64 Ohm = 40mW 120 Ohm = 20mW 300 Ohm = 8 mW 600 Ohm = 4mW
so suited for headphones to 64 Ohms. Above those impedances it simply won't go loud.
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XTRProf
Fully Modded
Pssst ! Got any spare capacitors ?
Posts: 5,689
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Post by XTRProf on May 11, 2012 0:13:58 GMT
I don't like chip amp and low power type. Period.
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