We are pleased to let you know that the Elektor Store now has the 13th edition of the ever popular Linear Audio series available for your enjoyment. This issue boasts the usual format of a series of bookzines dedicated to technical and audio perception. 
To name a few, this edition contains an article about Reed Relay Distortion — an article in which the authors present measurement data as well as simple models to estimate the 3rd-harmonic distortion contribution in a circuit, an article about the Axis Equalizer in which the author designs a special filter that reduces forward beaming, making the on-axis frequency response flatter, and  an article entitled "The valve DAC — Submicron silicon meets submillimetre vacuum" which features the author seeing how far he can get with building a DAC that has all critical analogue and mixed-signal functions realized in valve technology.
This is just a flavour of what the new edition holds for you, but it is definitely not one to be missed. Get your copy in the Elektor Store today.