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FS: B1 with Korg Triode/Bottlehead Quicksand - battery powered hybrid power amplifier

Price - $750

This is a modern DIY version of the amplifiers Redwine Audio used to sell. The preamplifier section is a PASS Labs B1 with Korg Triode (NuTube) kit. The amplifier section is a Bottlehead Quicksand kit. The battery is a 24v lithium ion. The chassis is a powder-coated and modded DAL audio replacement for Dynaco ST-120.

It was built to use a DAP as the source, which would mean there would be no wall powered components involved. I've successfully tested it with a wall powered source before.

The circuit works like this. When the switch is in the up position--amplifier is on, display/charging is off. When the switch is in the middle--everything is off. When the switch is down--amp is off, display is on/charging is enabled (charger is plugged in then); so down is used for charging and checking battery level.

The amp sounds great. Cosmetically, the amp is a 9. The battery used to last forever, but I let it get too low once. The battery is still good, probably a 7--most wouldn't need to charge it for week(s), I'm guessing. So I'd give it an 8 overall rating.

There are a few things to keep in mind. The amplifier has roughly 36dB of gain and therefore should be paired with a passive preamp or source with minimal gain. The B1 with Triode has built-in adjustments to shape the sound. This requires a screwdriver, voltmeter, and some intelligence to dial in best sound. NuTubes tend to be microphonic; this one has tamed over time and hardly ever reacts to anything now. Though, this is an open chassis and loud noises could vibrate the NuTube (think like a loud sneeze). Also, there is a startup thump--I went minimalist and opted not to install anything extra. That's the entire concept, no line noise and no extra parts detrimental to the circuit.

I can install a brand new battery for $150.

Optionally, I might part this out. It might be worth more money parted out if no one is interested in this type of build.

Comes with amplifier, smart charger, extra TPA3122 chip, and custom shipping box.
 

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