| Telefunken amp from the Concerto 2500 radio | |||||||||
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OK - this amp is not pretty, BUT it is one of my absolutely favourite units. It is found in the Concerto 2500 tube receiver and comes along with 2 of the coolest audio tubes I know: the Telefunken ECC83 and the Telefunken round plate EL84. The circuit is very simple and the unit sounds very nice in original condition. The output transformer is designed for 4 Ohms use only, so that the amp works best (better bass and output power) with 4 Ohms speakers.
What you should do for HiFi use:
1. Remove the equalization PCB. Instead of it you should solder 10kOhms resistors in the signal path (connector 1-2 and 5-6 - see picture below on the left).
2. Install an input jack. The easiest way is to use a DIN jack as there is a hole provided above the speaker connectors to install it. 3. Remove the power connector for the radio/preamp section to avoid electrical shock. (4. Add jumpers for correct speaker connection next to the 10k R's as shown in the picture. Not necessary in all units) If you want more: Disassamble the amp and rebuilt it (using the same PCB and OPTs) on a bigger chassis with a bigger power transformer. Use better filter caps and a choke in the power supply. With a B+ of 320V you will get 5 watts of great sounding ouput power! |
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