Combine them into a single package managed without significant compromises that basically boiled down to a decrease in power output terminal stages with 2 x 80 W up to 2 x 50 watts into 8 ohms. It does not matter, because the CD-Receivers are usually bought for work in small spaces. Much more important is that the amplification path is made not on the chips, as usual in compact devices and discrete components. Now for the design and ergonomics.
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This was really fun to build! He wanted a high-current version of the GFA, so we went all-out with dual Avel VA transformers, gigantic 27,uF filter caps, and a truly dual-mono layout throughout. This amp has dual power cords, fuses and power switches. The sound is just incredible! Perhaps the best one yet. Super clean and powerful, and never seems runs out of gas, right up to clipping. I measured W at 8 ohm and at 4 ohm just before clipping! That is one stiff power supply!
Dual power switches. This thing is truly dual-mono throughout. One must always be very careful when upgrading the power supply of an amp, so as not to overload it and possibly blow it up! The Safe Operating Area of the transistors must be considered. SOA of transistors in preceding stages must also be considered, as they could be under more stress driving upstream transistors that are now pushing more current. This mod bumps that to about W. So, we are not pushing the output section too hard, though we have given away some SOA headroom.
This upgrade is not without risk. It would have a little less 8 ohm power, but would also have even less sag. The Amphion One 15 is rated at 8 ohms, but of course all speakers have a curve. This one has a somewhat unusual impedance dip to nearly 2 ohms at 20KHz.
Zobel network maybe? I reckon what these speakers like is an amp that can deliver big current at high frequencies. The point of this upgrade is not so much the increased power output, but to improve the power supply regulation. The fact that it delivers nearly double power into halved impedance means the supply is barely sagging. This is an important feature for speakers with complex impedance curves, such as electrostatics, or speakers with complicated crossovers.
Avel Y Dual bridges feed the caps. Less hum than typical center-tapped, single rectifier layout Transformers are mounted face-to-face to null out some of the radiated magnetic field. Dual bridges like a lot of high-end amps made these days. Wima MKP 0. Less hum than typical center-tapped, single rectifier layout Completed boards. I had to hone flat the transistor mounting surfaces.
This is a common issue with the , but not the for some reason. The tapped screw holes are warped out and proud of the surface.
This makes for poor thermal contact. Such excellent transistors, and really consistent manufacturing. Dual power cords and fuses.
2SC3856 Datasheet, Equivalent, Cross Reference Search
A custom GFA-545 II with an insane power supply