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In Reply to: RE: Ether C headphone by MrSpeakers. posted by genungo on April 17, 2016 at 12:36:04
My little "zen" amp (N. Pass type circuit)
Edits: 05/07/16Follow Ups:
Wow, looks amazing!
The Zen amp has dual power supplies (two generously-sized transformers,two IXYS FBE22-06N1
fast / soft recovery rectifier bridges, etc) uses Silmic II electrolytics, Wima film caps, Alps "blue velvet" pot and is very heavily biased into Class A. This circuit has only ONE active device in the direct audio path, a Mosfet. It is a single-ended design, based on Nelson Pass ideas. (Although there is only one active device directly in the signal path, there are constant current sources etc that "feed" the device, and they certainly affect the sound. Still, this is a SINGLE STAGE SINGLE ENDED AMPLIFIER, and for that reason it can be thought of as being special.)
Since it's single-ended, there's DC at the output that needs to be blocked. The output capacitors in my version are 1,000 uF film caps, and I've also put in a switch allowing you to select a 1,000 Silimic II electrolytic instead- so you can A/B a film coupling cap vs an electrolytic.
The amp is fairly powerful, and can drive HiFiMan HE-6 headphones. The sound is tube-ish.
The Beta 22 has a few "special" touches. The power supply is completely (and safely) electrically isolated from the main chassis by Delrin plastic and rubber. This inner subchassis is connected to "third prong" AC safety ground, but the overall main chassis is not, and is connected only to audio ground. The power transformer is magnetically shielded. This arrangement provides all the advantages of a two-chassis design in a single chassis. Also, to maintain very low impedance in supply and return rails, all power rail wiring is 14 ga wire, soldered directly to the amp boards; the 0V return power rail is 12 ga. All wiring is teflon-insulated silver plated. (I don't know if using that kind of wire makes it sound any better- some would say so; what I like is the silver-plated wire provides a more reliable solder connection, and the Teflon insulation doesn't melt or pull back when you solder the wire, making for tidy wiring.)
The Beta 22 has a Goldpoint attenuator, mounted right next to the input jacks. The volume knob is on a long shaft, but I took care to mount it all very solidly and the volume knob was a very positive, smooth feel to it.
Both amplifiers have custom AC cords that I made, which are a little heavier (14 ga) than most, and have good quality IEC and power plug hardware on them to help them stay reliable for a long time. The cord is kind of nice, too- cloth covered which I think dresses it up a little.
"If people don't want to come, nothing will stop them" - Sol Hurok
....or my Beta 22 amp
Did you assemble and finish these amps yourself?
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