fligti91 said:
welcome to the wonderfull world of single ended classA
fligti91 said:
Get a datasheet on your particular brand of MPSA's and check the pinout carefully. Different makes can have different pinouts. (Rarely, but it is seen before) Just check that Base, Emitter and so on goes to the right connections.
And never forget: The schematic is correct
No doubt.Good luck
so if i run lower bias current with higher voltage than specified for original circuit what does this do to distortion? the article states that lower current induces more distortion but will more voltage help lower it? im just worried about how much more distortion ill get if i lower the bias current
This is not all that complicated.
You got like 2 A bias, so the heatsink will have to deal with 2A*45V=90W of heat.
I have no idea what your heatsink can handle, hence my advice yesterday, to not let it get warmer than you can touch it for a few seconds.
Mosfets has something called a de-rating curve, which is a curve that shows power handling VS. case temperature, see data sheet of IRFP9240 :
http://www.irf.com/product-info/datasheets/data/irfp9240.pdf
So if your mosfet temperature has gone through the roof, which I'm pretty sure is what happened, they go belly up.
One way to deal with this is to better the thermal interface from the mosfet, to the heatsink, another way is to get a bigger heatsink, or the last resort, a fan.
Magura
You got like 2 A bias, so the heatsink will have to deal with 2A*45V=90W of heat.
I have no idea what your heatsink can handle, hence my advice yesterday, to not let it get warmer than you can touch it for a few seconds.
Mosfets has something called a de-rating curve, which is a curve that shows power handling VS. case temperature, see data sheet of IRFP9240 :
http://www.irf.com/product-info/datasheets/data/irfp9240.pdf
So if your mosfet temperature has gone through the roof, which I'm pretty sure is what happened, they go belly up.
One way to deal with this is to better the thermal interface from the mosfet, to the heatsink, another way is to get a bigger heatsink, or the last resort, a fan.
Magura
fligti91 said:
Till you get a little control over this, putting 2 * 0R33 in series, to get 0R66 for R1, would make your life easier.
Later when you get some idea about what signs to look for, to not have things go bang, you can up the bias, and have fun.
It works just fine with 1A bias (0R66 as described above), it's not like it's going "klonk" and turns heavily distorted.
Magura
fligti91 said:
Well, you could probably get away with running one channel as it is, with that heatsink.
It would be worth trying, just monitor the temperature, and if it gets too hot to touch, turn it off again.
This way you can figure, if you just need to go buy another heatsink like the one you have, or more radical means are required.
Magura
ok first i would like to thank everyone for all the help. im sorry i havent gotten back to any of you for a couple of days but ive been stuck in my chair with this huge smile on my face because my amp finally WORKS!!!
this thing is so freaking clean and smooooth. this project was deff. worth it!
on a side note my q3's were correctly installed originally, after looking at the pinouts on the manufacturer's website i found that i needed to put them back the way they were with the emitter going to main power in. i also upped the r1 to .68 ohms.
the heat is under control. this thing sounds like its putting out way more than 10 watts though. im thinking with the 45v rails ive got to be getting more power. either way it got a pair of bookshelves very loud.
THANK YOU TO ALL THAT HELPED ME WITH THIS PROJECT
this thing is so freaking clean and smooooth. this project was deff. worth it!
on a side note my q3's were correctly installed originally, after looking at the pinouts on the manufacturer's website i found that i needed to put them back the way they were with the emitter going to main power in. i also upped the r1 to .68 ohms.
the heat is under control. this thing sounds like its putting out way more than 10 watts though. im thinking with the 45v rails ive got to be getting more power. either way it got a pair of bookshelves very loud.
THANK YOU TO ALL THAT HELPED ME WITH THIS PROJECT
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