Smooth dryers
Oh yeah, the smooth constant sound of a dryer.
I have used a vented and a few condenser Mieles, and nothing comes close to this smooth run they had.
The old ELux dryers at one laundromat are small, but beyond powerfull. They literally run no hotter then 140°F. If even. However, these things feel and sound the negative king of durable. Not exactly cheap, but just not smooth.
However, their home heatpump dryers with inverter motors and best the A+++ models are in my opinion the smoothest operators in HP dryers.
BSH has the silent dryers at 61-65dB, but I always thought that the heatpumps sounded rather annoying, and the start was always so weiredly "slow". First, condensing pump turned on, then light, the motor, the heater on condenser models clicked in, and all happend in well distinctable timeframes.
However, while the Whirlpool build dryers are far from bad, you really don't want on in living areas. These are loud, and run verry suttle. Their heatpumps have this tendency to cavitate (loud, destinctable compressor noise vs audible medium humming), and the motors have this clear sound of working motor with lots of speed variations that drasticly change motor noise, even with small loads.