The BAT topology is not exactly push-pull, but rather single-ended floating bridge(similar to Atma-Sphere), as described by Victor Khomenko:
"The VK60 is neither a traditional single-ended design nor a push-pull design. We refer to the VK-60 through VK-1000 amplifiers as single-ended bridge designs. This fundamental circuit dates back to the early 1950's and was invented by Henry Wiggins while working for the ElectroVoice Company. The original name for this type of output topology was Circlotron. The single-ended bridge design relies upon two single-ended amplifiers arranged in a floating bridge formation. This differentiates it from other forms of bridge topologies, most of which effectively incorporate two push-pull sides. The output circuit is inherently balanced and is driven differentially from a preceding stage. The two DC bias currents that exist in each half of the output stage cancel each other in the load. It is a more expensive way of building an amplifier as it requires multiple floating power supplies, as opposed to the more traditional ground-referenced supplies. The benefits of this approach, however, include enhanced symmetry when compared to push-pull designs and lack of the DC saturation problem inherent to single-ended designs."
After hearing an Atma MA-1 I was ready to sell my VK-75SE, but instead set about modding the piece to the point that I feel I'm getting similar performance. Both manufacturers provide excellent customer service, with Ralph at Atma going the extra mile regarding customization, upgrades, and long-term personal relationships with customers.
You can't go wrong with either of these similar designs. However Atma OTLs need to be closely matched to speakers with benign impedances, and they do run hotter.
"The VK60 is neither a traditional single-ended design nor a push-pull design. We refer to the VK-60 through VK-1000 amplifiers as single-ended bridge designs. This fundamental circuit dates back to the early 1950's and was invented by Henry Wiggins while working for the ElectroVoice Company. The original name for this type of output topology was Circlotron. The single-ended bridge design relies upon two single-ended amplifiers arranged in a floating bridge formation. This differentiates it from other forms of bridge topologies, most of which effectively incorporate two push-pull sides. The output circuit is inherently balanced and is driven differentially from a preceding stage. The two DC bias currents that exist in each half of the output stage cancel each other in the load. It is a more expensive way of building an amplifier as it requires multiple floating power supplies, as opposed to the more traditional ground-referenced supplies. The benefits of this approach, however, include enhanced symmetry when compared to push-pull designs and lack of the DC saturation problem inherent to single-ended designs."
After hearing an Atma MA-1 I was ready to sell my VK-75SE, but instead set about modding the piece to the point that I feel I'm getting similar performance. Both manufacturers provide excellent customer service, with Ralph at Atma going the extra mile regarding customization, upgrades, and long-term personal relationships with customers.
You can't go wrong with either of these similar designs. However Atma OTLs need to be closely matched to speakers with benign impedances, and they do run hotter.