something is wrong with your build if amp is malfunctioning
if you're asking for Iq setting, it's easy
if you put DVM probes across R16 or R18 , you have there 0R47//0R68=0R28, so for 1A8 you'll see 500mV
if you put DVM probes across R17 or R19 , you have there 1R//1R5=0R6, so for 1A8 you'll see 1080mV=1V08
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I used the kit-components pr. spec and I adjusted Iq to just below 1A9 with still room for some adjustment.
what?
work with me, if you have a problem and you want me to try helping to solve it
reply/confirm what I wrote in post #421
first make present amplifier properly
then, if you are able, try whatever you can to make it better; I can help with that too, but first thing first
如果放大器出现故障，说明您的构建有问题
如果你问的是智商设置，很简单
如果将DVM探针放在R16或R18上，则0R47//0R68=0R28，因此对于1A8，您会看到500mV
如果将DVM探针放在R17或R19上，则1R//1R5=0R6，因此对于1A8，您将看到1080mV=1V08
Sir, I don't think you've understood what I mean. Please forgive this lousy translation software. What I want to say is, can four IRFP150s be connected in parallel for the Babelfish f8?
OK, I understand.thank you sirsomething is wrong with your build if amp is malfunctioning
if you're asking for Iq setting, it's easy
if you put DVM probes across R16 or R18 , you have there 0R47//0R68=0R28, so for 1A8 you'll see 500mV
如果将DVM探针放在R17或R19上，则1R//1R5=0R6，因此对于1A8，您将看到1080mV=1V08
they can, but with changes in circuit, and only after explanation what intended goal is
can you clarify, then, do you have amplifier already made by present schematic, properly set ( standing current and DC Offset)?
Yes, I made it exactly according to your schematic diagram. It works quite normally. The static current is set at 1.5 to 1.8 amperes, and the midpoint voltage offset is about 60 millivolts. At present, I think its low-frequency performance is insufficient, so I plan to connect four IRFP150s in parallel.
what you are trying to drive with amp, which speakers?
I can't see how is possible that amp is not behaving well, if combined with adequate speakers
post some info, and pictures of your build
Could be interesting to hear about which speakers if they go below 1 ohm below 50 Hz.
The exact value of Iq should be known and it must be stable?
The exact value of Iq should be known and it must be stable?
Hey, would you believe me if I said I've found the cause? It's so touching! There was a 1000 microfarad capacitor on the PC817, but I used a 2200 microfarad one. After I replaced it with a 1000 microfarad capacitor, everything worked fine. I'm really sorry. I'd like to express my gratitude to all of you!
good that you solved your issue
though, I'm not sure that culprit was in value of cap you noted
it's important that it is big enough, but I can't see it's even possible it being too big in value
though, I'm not sure that culprit was in value of cap you noted
it's important that it is big enough, but I can't see it's even possible it being too big in value
I remember that I also encountered this problem when I was building the First Watt J2 amplifier before. There was also a capacitor next to the 4N35. However, increasing its capacitance actually made the performance worse. I really don't know why. 😢