I am currently building a Mofo to drive an efficient 100db 8ohm speaker. In my estimation, one or two watts RMS should be enough to have comfy or even loud volumes. For now I am building it according to the article with a 12V smps and IRFP250 biased at 1.7A. Does it make sense to look for a smaller mosfet that would bias with a smaller current and a smaller heasink? Any suggestions for parts to try?
Thanks. Any suggestions for min voltage and bias currents for it?
I had a deep dive in my stash but could not find any 510s. I'll get some on my next order.
I got lots of 610s and FQP3N30s though, so I'll probably start there
610 is good too
see Papa's ACA Mini for rails and Iq
say 15Vdc and no less than 200mA
more if you need more oomph!
see Papa's ACA Mini for rails and Iq
say 15Vdc and no less than 200mA
more if you need more oomph!
2 Watts works out something less than 7V and 1A. A third of the heat. I don't think you need to down-size the FET for such a small shift. I don't know that the energy savings justifies odd power supplies; 12V seems fine to me. You rarely regret having a little more power thna you think you need. (And it is easy to mis-estimate.)
I checked the ACA mini article again, and something like a 510 at 0.4A sounds really promising and will not require a huge heatsink. I will build both though and see how things work and sound
I haven't read the whole thread yet (I will), but can anyone recommend a production output transformer that could replace the capacitor on the output? What would the specifications for it be?
J&K Audio Design can build output transformers for solid state amps. I have a pair which I will be using for a SIT amp.
I suggest giving the capacitor output a try.
"The proof of the pudding is in the eating."
An audio grade electrolytic capacitor is perhaps $10 whereas an output transformer is hundreds of dollars. It's easier on the wallet to start with the capacitor. 🙂
"The proof of the pudding is in the eating."
An audio grade electrolytic capacitor is perhaps $10 whereas an output transformer is hundreds of dollars. It's easier on the wallet to start with the capacitor. 🙂
Of course the circuit will be built with a capacitor out in the first instance and may stay that way. 6,800uf is far beyond DC Link caps so has to be electrolytic, but I guess some have experimented with smaller bypasses.