YAMAMOTO A08-S User Manual

Amplifier kit

Table of Contents

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Horber Steige 25 * 72172 Sulz * Germany * Tel: ++49-1755382641

First we must say, for legal reasons it is not possible that our company JACMUSIC writes an official

manual for other companies products. However we answer often technical questions about the A08-S,

so we intend this document to be used only additional to what is officially supplied by the

YAMAMOTO SOUNDCRAFT COMPANY OF JAPAN.

An earlier version of this amplifier was called A08. This newer version is called A08-S, where the S

stands for the DC current meter, and lower hum of the output signal, and replacement of the 5U4G

tube with the Type 80 tube.

The A08-S is supplied by the factory as pictured above, with 8 Ohms output. A special version can be

ordered, such as amplifiers designed for Western Electric 205D tubes, or a 16 Ohms output.

Materials used

The wood is cherry, which is beautiful looking by itself, but not very suitable to construct a tube

amplifier directly. So before use, the wood is specially treated by Yamamoto, called the Shashih

process. This process significantly increases the hardness, and in this way, the thread of the screws can

be cut directly in the wood, even for very small screws like 3mm, this works excellent. Also the

www.jacmusic.com

Copying of this document is not allowed, also not partially, and also not for private publication in the internet. In case of

Yamamoto A08-S Amplifier Kit

August 24

www.jacmusic.com

* Horber Steige 25 * 72172 Sulz * Germany * Tel: ++49-1755382641

2009 b

Table of Contents

Do you have a question about the A08-S and is the answer not in the manual?

Page 1 Type 80 tube. The A08-S is supplied by the factory as pictured above, with 8 Ohms output. A special version can be ordered, such as amplifiers designed for Western Electric 205D tubes, or a 16 Ohms output.
Page 2: Tubes Replacement
Tubes replacement Great care must be taken that the tubes for your A08-S are in good condition, since best sound can only come this way. Saving money on tubes is the worst you can do, when good sound is what you want.
Page 3 With EML 45 tubes With RCA 245 tubes From historical production all 45 can be used when they have sufficient emission. This can be seen from the plate current on the meter, it must be approximately 32mA, and not drop at high loudness. End-of-Life with 45 tubes.
Page 4 Not so with the A08-S! The bottom cover of the A08-S is one single piece, and when it is removed, all parts can be very conveniently reached even from the sides, for service or repairs. Though perhaps not important when new, your service technician will be satisfied to see how convenient it is, to work an the A08-S.
Page 5 Switch on: . The A08-S may only be switched on with the Speakers connected and with the inputs connected, and all tubes inserted. (Exception 717A tubes, read next part below).
Page 6: Specifications
These are very hard to identify, and you may have no clue where it comes from, and accuse the wrong parts of the equipment. A simple way to find this out with the A08-S, is to remove the 717A tubes while the amplifier is OFF.