Audio Power Labs
The Audio Power Labs exhibit took my breath away, Imagine, a huge, beautiful $175,000 per pair, 200Wpc monoblock tube amplifier using 833C, graphite-plate, radio-frequency transmitter tubes that have a bandwidth of 30MHz and run with 1500V on the plates! These tubes were used in the output stage of BCF-1 radio transmitters. Now imagine that the amplifier's designers are named Squeek Rieker (right) and Peeya Iwagoshi (left), and you know why I had to pinch myself to make sure I wasn't dreaming.
Audio Power Labs buys the 833 Richardson in Texas who imports them from China. Lots go through a matching process that yields 60 pairs, with the rest sold on eBay at cost.
The microprocessor-controlled amplifier has no capacitors in the signal path. It has less than 1% THD at rated output with a frequency response of 15Hz33kHz ±3dB. The company also sells the 50W 50TNT monoblock for $47,500/pair. It has a frequency response of 15Hz25Hz, ±3dB with less than 2% THD from its 8 ohm output tap. Unlike the 833TNT, its 572B output tubes are no longer manufactured, so Audio Power Labs has sourced over 700 tubes for their production and warranty work.