thanks silvio , the tl074/84 is a very sensitive area . if i put chinese tl074/84 they don't work but consumes a lot of current. same as the bc337/327 they have to be genuine parts .Regarding the NE5532A (from Texas instruments) it is claimed to go up to 10Mhz. This should be fast enough for the 240Khz you may be needing.
I would like to understand why are the output fets heat up with a particular transistor. Is it the waveform produced, the noise, bias, gain, output swing, amplitude etc? Understanding why will help you cure the problem using different transistors I guess. As I can see you surely need a complimentary pair not to say matched for your need. These need to work together and have the same symmetry in their outputs.
Hi Stewin, I called a friend of mine and asked about your choice of ICs. He mentioned a few and told me that they are direct replacement for each other. He also told me that it would be better to use 2 dual op-amps instead of a quad one for the reason to minimize cross talk. His experience is rather dealing with pre amplifiers rather than class d. Your particular use may be somewhat different as here you only need to generate the triangular wave form for the base frequency of the amplifier. I am listing a few iCs for you whom are directly replaceable with each other regarding input, output and supply pins.hi silvio . will this below quad opamp work??
thanks silvio for the reply. this amp is robust and works flawless without any hf noise and comfortably handles 2ohms load per channel with +/-49volts . the only issue is that you have to use geniune tl074/84 and bc327 and bc337 if you use counterfeit the amp will draw alot of current and it will produce nasty hf noise at outputIf I am correct it seems that you opted for 4 X 200w mono amplifiers. I guess that is a very versatile setup. It can take 4 X 15 inch speakers whenever needed and having a total of 800w power. I seen this made in pro amplifiers. A common heatsink for every two amps will make a good stack and can fit in a 2U box. My guess having 4 separate volume controls and 4 separate preamps which can make a bridged pair thus either having a stereo unit with bridged amps or 4 mono. This will need 4 separate inputs and 4 separate outputs.
One last note. Have you tried a band pass filter for reducing HF noise in the input? Are you using an smps to drive these amplifiers? Some carful screening maybe also passing a grounded trace between the signal traces may help you out. Just some ideas that cropped up for you.