ppl
Building amps and assuring water resistance.
- Joined
- Jun 21, 2001
- Posts
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Regarding Your Concerns
(1)The PPA prototype board I using has OPA637/627 combo and bias @ 16-20 Ma no stability issues. With the Triad Module the primary reason that stability issues arise were too low of a bias 10mA combined with having the Module socket and mounted what are stilts placing the output stage well away from the remaining circuitry. In addition since the PPA2.0 has the buffer on board and as an integral part of the board then the rest of the amp can be designed to accommodate this. So with the default @20 mA this will not be a problem.
(2)While not finalized yet alternate resistor values in the emitter stage for portable low bias use and high bias home use.
(3)AMB correctly pointed out that the Bias is also adjustable with a trim pot so one could set it with in reason to achieve there desired goal
(4)As for concerns regarding the sound everyone that has replaced the IC buffers with 5002’s have reported sonic improvement not one person has
reported a reduction in sound so these concerns are not warranted
(5)Regarding the LED I think that one led position to the side is plenty as was done on the M3
(6)With the Bass boost pot mounted in the center this places the volume control, Bass boost and Headphone Jack at even intervals and surly one would not use the same size Knob for bass boost as they would the Volume. There are exceptions Like xtreme 4099
(1)The PPA prototype board I using has OPA637/627 combo and bias @ 16-20 Ma no stability issues. With the Triad Module the primary reason that stability issues arise were too low of a bias 10mA combined with having the Module socket and mounted what are stilts placing the output stage well away from the remaining circuitry. In addition since the PPA2.0 has the buffer on board and as an integral part of the board then the rest of the amp can be designed to accommodate this. So with the default @20 mA this will not be a problem.
(2)While not finalized yet alternate resistor values in the emitter stage for portable low bias use and high bias home use.
(3)AMB correctly pointed out that the Bias is also adjustable with a trim pot so one could set it with in reason to achieve there desired goal
(4)As for concerns regarding the sound everyone that has replaced the IC buffers with 5002’s have reported sonic improvement not one person has
reported a reduction in sound so these concerns are not warranted
(5)Regarding the LED I think that one led position to the side is plenty as was done on the M3
(6)With the Bass boost pot mounted in the center this places the volume control, Bass boost and Headphone Jack at even intervals and surly one would not use the same size Knob for bass boost as they would the Volume. There are exceptions Like xtreme 4099