Audvance upgrades for your Telefunken M15A 
For maximum sound quality we have dramatically improved on the audio boards of the M15A by designing all new record and playback boards. Integrated circuits and transformers have been removed from the signal path, as well as overall feedback. All filtering is passive. Now the performance of the electronics finally matches the performance of the wonderful mechanics of these machines.
Playback amplifier M15A for all speeds (BC-WV replacement)
• No transformers on input or output side needed • All discrete circuitry with no IC's in signalpath • JFET low noise input stage (with multiple LSK170) • Vishay/Dale resistors throughout • Polypropylene caps in signal path • No global feedback applied • Passive filters • Active power supply noise filter • Relays instead of FETs used for switching • Switchable NAB and IEC/CCIR equalization • Multiple equalization time constant options with jumpers • Handle makes is easier to remove board and fits under metal cover • Handbuilt in the Netherlands
This all new designed board supports both 19/38cm/s and 38/76cm/s machines and is perfect to play your favourite master tape copies. There are no input or output transformers any longer, which would be sensitive to electromagnetic fields and cause non-linear distortion. Instead a low noise JFET input stage is directly connected to the playback head and avoids any DC current flowing through it. A discrete balanced output stage with zero phase difference -among the phases- drives the outputs, driving long lines with ease. The signal path from input to output is optimised for sound quality. That means that you can expect the most natural and uncoloured sound that is possible with three-dimensional staging and amazing dynamics. High-end audio quality that is. Top quality components, creative circuit design and the lack of overall feedback are the main ingredients for this result. The circuit is very linear by itself so there is no need for overall feedback. Remaining distortion is very small and mainly second order, similar to tube amplifiers. Due to the lack of feedback output noise is 4dB higher (A-weighting) compared to the original board, put practically undetectable from the listening seat. The output level is lowered to match the output level of modern sources in a high-end system.
Switching of the equalization between NAB and IEC/CCIR is supported and is similar to the original board. With a single jumper the board can also be set into either equalization. Adjustments with pots are limited to level and upper time constant for each speed (high frequency adjustment). Selectable time constants at 19cm/s and CCIR are 50μs, 70μs and 100μs. With NAB a selection is possible between 30μs (Telefunken default) and 50μs. With Audvance boards in place the record-playback cycle has a frequency response (with Vacodur heads) of 20Hz-23kHz (+1/-3dB) at 19cm/s and 23Hz-31kHz (+2/-3dB) at 38cm/s. Details about this board can be found here.
Price: € 699 (per channel)
Add to cartRecord amplifier M15A 19/38 cm/s (BC-AV replacement)
• No transformer on input side needed • All discrete circuitry with no IC's in signalpath • Vishay/Dale resistors throughout • Polypropylene caps in signal path • No global feedback applied • Passive filters • Active power supply noise filter • Relays instead of FETs used for switching • Increased bias level fits modern tapes • Switchable NAB and IEC/CCIR equalization • Handle makes is easier to remove board and fits under metal cover • Handbuilt in the Netherlands
This all new designed board supports 19/38 cm/s machines. There is no input transformer here, which would be sensitive to electromagnetic fields and cause non-linear distortion. A new proprietary balanced input circuit replaces the input transformer, not having any of its disadvantages. Common mode input noise is effectively rejected by it. The output stage is balanced too and is DC coupled to the recording head, avoiding a large capacitor in the signal path. The signal path from input to output is optimised for sound quality. That means that you can expect the most natural and uncoloured sound that is possible and sonically is a match with high-end audio and top-of-the-range professional equipment. Top quality components, creative circuit design and the lack of overall feedback are the main ingredients for this result. Due to the lack of feedback noise is higher, but only marginally at 1.6dB (A-weighting) compared to the original board.
Switching of the equalization between NAB and IEC/CCIR is supported and similar to the original board. With a single jumper the board can also be set into either equalization. Adjustments with pots are also similar to the original board. With Audvance boards in place the record-playback cycle has a frequency response (with Vacodur heads) of 20Hz-23kHz (+1/-3dB) at 19cm/s and 23Hz-31kHz (+2/-3dB) at 38cm/s. Details about this board can be found here.
Price: € 699 (per channel)
Add to cartExtension board
• Easy bias trimmer adjustment of record amplifier • Easy measurements on all audio cards • 4-layer board with top and bottom shielding • Direct output of playback head • Handle makes is easier to remove board and fits under metal cover • Handbuilt in the Netherlands
With this board you get easy access to controls and components on any audio card. On the Audvance record amplifier there is a bias trimmer that can only be accessed with this board in place. This board can also be used instead of a playback board when you would like to use an external tape preamplifier. The signal from the playback head is directly available on a three pin connector on the front. Details about this board can be found here.
Price: € 149 (each)
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