People here, seems to turn themselves shocked with chips.
This is some "second class" audio amplifiers for some purists...some hi level exigence audiophiles.
I think the have some reason, despite that the idea is very interesting.
If you want people to came fast....let some error....this way, many will be motivated to enter, as they will help you. If everything well made...they will see and think...hummmm, and go away.
regards,
Carlos
This is some "second class" audio amplifiers for some purists...some hi level exigence audiophiles.
I think the have some reason, despite that the idea is very interesting.
If you want people to came fast....let some error....this way, many will be motivated to enter, as they will help you. If everything well made...they will see and think...hummmm, and go away.
regards,
Carlos
the reason for the fuse is simple, the amp ( lm3886 ) has a quiesent current of 50mA, this is the current thrue the 220ohm resistors, the voltage over this resistors should be ~0.6V, but it is infakt 11V, so the whole circuit acts like a short circuit.
If you or only going to use a 8ohm load, just leave the transistors out, if you look at the datasheet of the chipamp you wil see the amp can perfektly handle 8ohm loads.
there is no need to make this hobby more difficult as it is
Rudy
If you or only going to use a 8ohm load, just leave the transistors out, if you look at the datasheet of the chipamp you wil see the amp can perfektly handle 8ohm loads.
there is no need to make this hobby more difficult as it is
Rudy
rudy,
the resone i added the transistors is because i only had 1 chip left and 50 transistors, second resone is i was thinking of getting +-100 watts. its for a subwoofer amp... is there any way to chang something so that the amp will work like i expected? 68watts(more like 50) is not enough for me at the moment....
Thanks,
Kinser
the resone i added the transistors is because i only had 1 chip left and 50 transistors, second resone is i was thinking of getting +-100 watts. its for a subwoofer amp... is there any way to chang something so that the amp will work like i expected? 68watts(more like 50) is not enough for me at the moment....
Thanks,
Kinser
1. try using 12ohm resistors instead of the 220ohm
2. the 0.1ohm resistors should be located between the supply and the emitter off the transistors( not on the collector ), and you better use some higher values, like 0.22 or 0.47ohm
after this you should check the quiesing current off the whole amp, if it is still to mutch then lower the resistor of 12ohm.
but 1 thing i just have to mension, you cannot go with a higher supply voltage then 42V, or you will destroy the chipamp.
Rudy
2. the 0.1ohm resistors should be located between the supply and the emitter off the transistors( not on the collector ), and you better use some higher values, like 0.22 or 0.47ohm
after this you should check the quiesing current off the whole amp, if it is still to mutch then lower the resistor of 12ohm.
but 1 thing i just have to mension, you cannot go with a higher supply voltage then 42V, or you will destroy the chipamp.
Rudy
Try R2=R3=1 ohms 1W or 2.2 ohms .5W and R6 and R7 in series with the emitters
If you are using a single pair of output devices, R6 and R7 may be omitted on this circuit, otherwise 0.1 ohms is a suitable value
For this circuit to work properly you must ensure class B operation and force low gain for the boost transistors
Also, some chip amps may be powered up to its absolute maximum rated rails provided their output current is kept low so SOA is not exceded
If you are using a single pair of output devices, R6 and R7 may be omitted on this circuit, otherwise 0.1 ohms is a suitable value
For this circuit to work properly you must ensure class B operation and force low gain for the boost transistors
Also, some chip amps may be powered up to its absolute maximum rated rails provided their output current is kept low so SOA is not exceded
Eva,
Two think you told me to do:
1."For this circuit to work properly you must ensure class B operation and force low gain for the boost transistors"
2."Also, some chip amps may be powered up to its absolute maximum rated rails provided their output current is kept low so SOA is not exceded"
As for no' 1 how do I do that? how to ensure that its calss B operation? how to force low gain for the transistors?
As for no' 2 the SOA fore the mjw21195/6 is 2.25A, 80V, 1 second. is this ok for 35vdc+/-?
BTW i am using only one pair of transistors..!
Thanks,
Kinser
Two think you told me to do:
1."For this circuit to work properly you must ensure class B operation and force low gain for the boost transistors"
2."Also, some chip amps may be powered up to its absolute maximum rated rails provided their output current is kept low so SOA is not exceded"
As for no' 1 how do I do that? how to ensure that its calss B operation? how to force low gain for the transistors?
As for no' 2 the SOA fore the mjw21195/6 is 2.25A, 80V, 1 second. is this ok for 35vdc+/-?
BTW i am using only one pair of transistors..!
Thanks,
Kinser
Delete R6, R7, not needed unless you add more outputs.
R2, R3 should be on the order of 1 ohm, this will force it into class B operation. If you have some cheap plastic TIP35C and 36C around use them, they might actually work better.
If you bridge a pair of these with the 1 ohm and the TIPs with ±40V or so, youcan get 400W at 4 ohms.
R2, R3 should be on the order of 1 ohm, this will force it into class B operation. If you have some cheap plastic TIP35C and 36C around use them, they might actually work better.
If you bridge a pair of these with the 1 ohm and the TIPs with ±40V or so, youcan get 400W at 4 ohms.
Thanks djk,
I will try it without R6 and R7, I didnt use mosfets for the output boost because I dont have any, and here in Israel thay are expensive, and because I dont know which ones to get. (could you suggest which ones are preferred)
I have just ordered some OPA549, OPA548 and some OPA541 power op amps, maby I could try use mosfets with these amps
Thanks,
Kinser
I will try it without R6 and R7, I didnt use mosfets for the output boost because I dont have any, and here in Israel thay are expensive, and because I dont know which ones to get. (could you suggest which ones are preferred)
I have just ordered some OPA549, OPA548 and some OPA541 power op amps, maby I could try use mosfets with these amps
Thanks,
Kinser
djk,
Ammm... about the mosfets, I know someone else wrote that.. I was refering to who ever read the post... dosn't matter.
I used the mjw2119x because I orderd them as samples from
"On Semi" 25 of each + MJL4302A and MJL4281A, 25 of each.
I have took out R6 and R7 and changed R2 and R3 to 1 Ohm resistors... now all I need is to go and buy the fuses (BTW the power supply is from a "Creek Audio" 4330mk2 integrated amp, 250VA toroid transformer!
Thanks,
Kinser
Ammm... about the mosfets, I know someone else wrote that.. I was refering to who ever read the post... dosn't matter.
I used the mjw2119x because I orderd them as samples from
"On Semi" 25 of each + MJL4302A and MJL4281A, 25 of each.
I have took out R6 and R7 and changed R2 and R3 to 1 Ohm resistors... now all I need is to go and buy the fuses (BTW the power supply is from a "Creek Audio" 4330mk2 integrated amp, 250VA toroid transformer!
Thanks,
Kinser
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