The V72 was developed by the German broadcast station NWDR. Together with the V76, these two amplifiers replaced the older V41. The first versions of these amplifiers were built by the firm Maihak AG, afterwards the main-production went to Siemens & Halske. This Amplifier was introduced to the German broadcast stations in 1952.

Comparing with the older version V41, the V72 became a fixed gain of 34 dB from two EF804S, which were mounted upside down in this amplifiers.

The input-transformer, which made Siemens for their amplifiers by themselves, was a disc coil transformer too. The ratio turn was 1:20. The V 72 input transformer has had only six discs, two primary and four secondary windings. The shield for this input-transfromers was a multi layer design with mu-metal and copper. If you want to buy any of these amplifier please pay attention to this input-transformer. Often it has one broken winding.

As the most other amplifiers developed for the German broadcast stations, the V72 has had a reduced wave band from 40Hz to 15kHz too.

Two years after introducing the V72, the V78 was developed. The V78, which was only produced by Siemens & Halske, was a copy of the V72, but has had a variable gain from 50dB to 70dB. This gain increase was reached by using a modified input transformer, but therefore, the frequency respond was smaller.

On the following pages you will find a lot of pictures of an opened V72 and a lot of points how to fix problems. Also we want to show you, hoe you can repair the output and input transformer, when it is broken

• Spare Parts (will come)
• More Pictures with a detailed discriptions of all parts and how to repair them
• Schematics (view/download .pdf)
• original V 72 "Braunbuch" discription (contains complete shematics of V72/download .pdf)
• original V 78 "Braunbuch" discription (contains complete shematic of V78/download. pdf)