Yamamoto Sound Craft A-06-3 AD1/AD-1M Single Stereo Amplifier

This single stereo power amplifier uses the AD1M, a modern reproduction of the famous European AD1 vacuum tube. The AD1M is a single two-stage amplifier that maximizes the appeal of the output tube and uses the long-life, highly reliable C3m vacuum tube for clear sound across the entire bandwidth. The power supply uses a current regulator circuit for a clean and energetic sound.

Single stereo power amplifier employing AD1M, a modern reproduction of the famous European AD1 vacuum tube

The maximum output power of 4W × 2 is obtained in a single configuration as a simple circuit configuration to take advantage of the character of the triode output tube. Tubes can be selected from Emission Labs and Telefunken products, so that the characteristics of each can be utilized.
The rectifier tube also uses the same side-contact type European vacuum tube AZ-4 as the AD1, and all the tubes are made in Europe to achieve a European sound. A self-biased circuit is used to ensure stable use of the valuable AD1/AD-1M vacuum tubes, and the characteristics of the AD1 are brought out by the non-reduction configuration.

An ammeter is provided to check the output tube current at any time.
Polypropylene film capacitors are used for the capacitors for quick response and low distortion, and all transformers are high-performance high-beam type original cut-core transformers with Teflon insulation paper to achieve excellent sound with low distortion. A timer relay is inserted in the output tube grid to ensure reliable use over a long period of time.
The input terminals are the company's original pin jacks employing chrome copper, and the speaker terminals are made of pure copper. Although the speaker terminals are 8Ω output terminals only, there is nothing wrong with using 4Ω or 16Ω speakers. However, in either case, the maximum output power will be reduced; a maximum output power of 8W will be reduced to about 4-6W.

Type	AD1/AD-1M Single Stereo Power Amplifier
Tubes used	AD1/AD-1M x2, C3m x2, AZ-4 x1
Maximum output	4W+4W
Frequency Response	20-20kHz
Input impedance	200kOhms
Size	480(W)325(D)200(H)mm
Weight	14.8kg

The reproduced sound is clean and simple, based on a good range expansion around the midrange. The tone and sound quality are smooth and refreshing to the ear. Listening was done mainly with Emission Labs, but the vintage Telefunken output tubes have a good persistence in terms of sound quality.
*analog
The Telefunken tubes are relaxing and gentle, while the Emission Labs tubes are crisp and fresh. Although the overall reproducibility is compact, it is enjoyable to listen to small ensembles, focusing on the appeal of the realistic reproduction of the flesh tones of the singers. For general use, it can be enjoyed without worrying about small output.
*analog