Some Questions
Hi, I know this thread has been inactive for a while, but I don´t know where else to ask. I´m willing to build this amplifiers and I have a few questions:
1º - I want to use IRFP250 instead of the original 240, it has higher current capability (30A vs. 20A), higher power dissipation (190W vs. 150W) and lower RDSon, which I think might translate in less heat dissipated by the amplifier (correct me if I´m wrong); all of this should make a more reliable amp, I think. In the other hand it has a higher imput capacitance (2800pF vs. 1300pF), which if I´m correct would translate in increased distortion; It is going to be used as a subwoofer amp, do you think this would affect performance in a considerable way?
2º - I am planning to use LM350T (TO 3P metal package),with a heatsink, instead of LM317K (TO3 metal package), the first is a higher current version of the other (3A vs. 1,5A), because it is easier to add this package in the PCB, would it be ok?
3º - I saw some photos of the amp finished and I saw one of the transistors mounted upon one of the output devices, as thermally tracking, is that correct? Is it Q 13?
Thanks in advance, Chalo.
Hi, I know this thread has been inactive for a while, but I don´t know where else to ask. I´m willing to build this amplifiers and I have a few questions:
1º - I want to use IRFP250 instead of the original 240, it has higher current capability (30A vs. 20A), higher power dissipation (190W vs. 150W) and lower RDSon, which I think might translate in less heat dissipated by the amplifier (correct me if I´m wrong); all of this should make a more reliable amp, I think. In the other hand it has a higher imput capacitance (2800pF vs. 1300pF), which if I´m correct would translate in increased distortion; It is going to be used as a subwoofer amp, do you think this would affect performance in a considerable way?
2º - I am planning to use LM350T (TO 3P metal package),with a heatsink, instead of LM317K (TO3 metal package), the first is a higher current version of the other (3A vs. 1,5A), because it is easier to add this package in the PCB, would it be ok?
3º - I saw some photos of the amp finished and I saw one of the transistors mounted upon one of the output devices, as thermally tracking, is that correct? Is it Q 13?
Thanks in advance, Chalo.
hi chalo
greetings
1 irfp 250 is being used in my amp have had no problems but they need to be matched
2 mje 350 attached to output transistor
3 use lm 317t more than adequate
thanking you
andrew lebon
greetings
1 irfp 250 is being used in my amp have had no problems but they need to be matched
2 mje 350 attached to output transistor
3 use lm 317t more than adequate
thanking you
andrew lebon
Hi Andrew, thank you for your fast reply, what might happend if I don´t match my mosfets? mje´s ar in place of Q13? why did you used that insyead of IRF610 (if this is the case)? and last is ok to use a common plastic lm317 (not TO3 metal) I´ve read that it gets pretty hot.
Thank you again.
Thank you again.
MJE was in place of Q12 but the component values around that were different. Use Q12 as shown in the schematic.
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