Check the post 37: http://www.diyaudio.com/forums/showthread.php?postid=854432#post854432
I just bought two of those board to use with Zv9.
I just bought two of those board to use with Zv9.
steenoe said:
I was thinking along those lines also, MoeI am in the process to see if it is possible to pursuade Russ White into it
Steen
Hi Steen,
Indeed, I am very excited about the project/PCB. I am working up the schematic right now and will be drawing the PCB soon. I am still doing some reading to be sure I understand what I am doing as much as possible, but I think it will be a very fun project.
I will be looking for input from everybody, and I hope I can get as much great help with this one as I did with Twisted XBOSOZ.
Cheers!
Russ
power supply load...
I'm using psud2 to design a ps for this amp. My 50/50 plitrons may work if I use an lclc filter (10mH@.1ohm), thus dropping the voltage to around 52 volts. That's assuming the ZV-9 offers a 25 ohm load. Hence, my question: is 25 ohms correct? Now, how to lose another 2 volts... (I may be losing my marbles)
Thanks,
John
I'm using psud2 to design a ps for this amp. My 50/50 plitrons may work if I use an lclc filter (10mH@.1ohm), thus dropping the voltage to around 52 volts. That's assuming the ZV-9 offers a 25 ohm load. Hence, my question: is 25 ohms correct? Now, how to lose another 2 volts... (I may be losing my marbles)
Thanks,
John
0R47 at 3W . . . ? Most probably too small . . .
0R47 takes a role of sensing the amount of the output ac current.
By the way, as the bias is abt 2A with 50% ac current gain, max output I(rms) could be 0.71x4A . . . then, the time-evrage power is 0.5 x 4 x 4 x 0.47 =3.76W . . . I would use . . . mmm . . . 5W rating. Or, 1R 3W // 1R 3W, i.e. 0R5 6W.
Regards
jh
0R47 takes a role of sensing the amount of the output ac current.
By the way, as the bias is abt 2A with 50% ac current gain, max output I(rms) could be 0.71x4A . . . then, the time-evrage power is 0.5 x 4 x 4 x 0.47 =3.76W . . . I would use . . . mmm . . . 5W rating. Or, 1R 3W // 1R 3W, i.e. 0R5 6W.
Regards
jh
BDP is correct. A 2 or 3W resistor is fine.
It's a question of continuous output power, not peak. Let's be generous and say that you're pushing the amp to 20W. Assuming an 8 Ohm load, that's a little less than 1.6A. Using the I(squared)R formula for wattage, a .47 Ohm resistor will experience about 1.2W of heat.
Music being music, it's not going to run the amp to full wattage all the time unless it's grossly overdriven. An old rule of thumb says that the peaks are ten times the RMS power. If you grant that assumption, the actual power dissipation will be less than one-eighth watt.
Still, it's best to be ready for a full power bench test. Use the 2 or 3W, whichever is handy. I use a 3W in cases like this, not because the part can't take it, but so that the resistor will be more comfortable to touch if I'm prodding around in the circuit.
Resistors are robust devices and can take an absurd amount of punishment. You could probably use a .25W part for normal use and a 1W for bench testing, but they would burn you if you touched them. After a while, they would discolor. So would the board. So would your finger.
Grey
It's a question of continuous output power, not peak. Let's be generous and say that you're pushing the amp to 20W. Assuming an 8 Ohm load, that's a little less than 1.6A. Using the I(squared)R formula for wattage, a .47 Ohm resistor will experience about 1.2W of heat.
Music being music, it's not going to run the amp to full wattage all the time unless it's grossly overdriven. An old rule of thumb says that the peaks are ten times the RMS power. If you grant that assumption, the actual power dissipation will be less than one-eighth watt.
Still, it's best to be ready for a full power bench test. Use the 2 or 3W, whichever is handy. I use a 3W in cases like this, not because the part can't take it, but so that the resistor will be more comfortable to touch if I'm prodding around in the circuit.
Resistors are robust devices and can take an absurd amount of punishment. You could probably use a .25W part for normal use and a 1W for bench testing, but they would burn you if you touched them. After a while, they would discolor. So would the board. So would your finger.
Grey
Grey
Yeah . . . I entirely agree with you about all details.
I just started my thinking from the extreme case. And, if all safe at the extreme point, we could stretch our legs and make ourselves eased. If there is apace for a bit bigger resistor and the price is minor part, why not . . . ? . . . Of course, we already have many of 2W or 3W grade sleeping in our room and like to wake them up . . . then . . . 
jh
Yeah . . . I entirely agree with you about all details.
I just started my thinking from the extreme case. And, if all safe at the extreme point, we could stretch our legs and make ourselves eased. If there is apace for a bit bigger resistor and the price is minor part, why not . . . ?
. . . Of course, we already have many of 2W or 3W grade sleeping in our room and like to wake them up . . . then . . . jh
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