GE 12AU7/6189W Vacuum Tube Review w/ Upscale Audio's Kevin Deal 

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Helically-wound filaments baby! Kevin recently found a stash of these, and soon as we'd tested a big enough batch to give us the tightest possible matches, these NOS tubes went out into the world and sent back rave reviews.
Robert H. Levi wrote in Positive Feedback: “In addition to excellent definition, the GE 6189 tubes were the quietest 12AU7 types in the world. ... With the quiet came added definition, layering, blacker background, and greater realism.”