About Gold plating of contacts:

With the gold plating process of low cost products, a layer of nickel is put on the material first, and after that the gold alloy plating is done, (not pure gold). as thin as technically possible.

The reason is, a gold layer will not give a shiny surface on metals like copper or bronze. So, first they put a mirro shining nickel layer, and then a gold alloy is applied on that. Nickel layer gives the mirror e shiny surface that people relate to "pure gold". In reality, the gold-over-nickel technology is lower cost, better looking, and frankly it does the job.

Yamamoto has another process: For best Sound results, all Yamamoto's connecting devices are made completely nickel-free by definition and by company philosophy. All base materials are BRONZE. However, bronze can not be fold plated well. For best properties, first a silver layer is put on the bronze. Then over the silver plating a gold layer is applied. This will give the gold layer it's Yamamoto-typical opaque surface, with superior contact proportions, for better sound. Also you will notice the pin soldering is much easier to do. This gold plating with 100% pure gold, will have the much deeper yellow color, which is typical for 24k gold .

About the Yamamoto contact pin material:

All contact pins are made of a solid blocks
of bronze, and are nickel free. They are CNC machined to get the shape they have. With the Noval sockets, this needs a CNC machine that can also do parts for watches!

Contact bronze is a special alloy of mainly copper and zinc, and it is superior to any other contact Material. It can only be tooled on
CNC machines, so is not used in commercial devices.

The pins can be taken apart for cleaning or adjusting the pulling force. Also with the very fine made 9 pin miniature socket.

Silver Version
Order Number: 320-019-67

Silver Version only

WIth this socket you can much increase your possible choice of tubes. Use of 1930's European tubes and USA tubes are possible in the same circuit now!.

Even though European tubes are 4V and USA tubes at 5V, it can be done. So this socket combines:

• European B4 base (normally 4V tubes)
• USA UX4 base (normally 5V tubes)

Part 1. Use 4V or 5V Rectifiers by just plug them in.

European rectifiers are available in much nicer variations, globe glass and mesh types can be found still. When you do this with a 5U4G circuit, the 5Z3 is the UX4 version of 5U4G. So this is the one tube. The European tube is RGN2504, PV200/600 or AZ50. (See our NOS pages) for rectifiers. Or switch from Type 83 mercury to AX50 Mercury.

The difference in filament voltage is solved with small series resistors. These do not even get very warm, and can be mountectly on the socket, and that's all you need to do.

Click here to see how it's connected for rectifiers.

Part 2. Use 4V or 5V Triodes by just plug them in.

This socket combines an UX4 socket with UV4 sockets. Why is that?
When you build a 205D amplifier, you can use the Fullmusic 205D, which has a UX4 socket.
Then later, just suppose you get the idea to try NOS 205D, these have an older type socket (UV4).
With this socket, all you need to do is rotate the tube 90 degrees, and it will take both types.
There are many other interesting tube combinations possible with this socket.

READ ALSO with the UX4-B4 socket for ideas about possible other applications.

Gold version only

Loctal
Tubes like: C3g, C3m, ECH21

I am sorry, as much as we like the Yamamoto sockets: We do NOT recommend to the Yamamoto LOCTAL socket.

Instead, we were able to buy a large stock of NOS Teflon sockets made by EDISWAN, England. These have silver plated contacts, and the same screw hole dimensions as the Yamamoto.

Order number for the EDISWAN TEFLON socket:
398-803-99

More information here

Only Gold Version

Application #2 (28mm to 38mm screw distance)

This allows to mount the Yamamoto 18mm hole socket in standard 30mm holes, as for octal sockets. Very useful when you want to use a noval based tube, where these is an octal hole in the amplifier deck.

The small holes of the base plate are used to mount the Yamamoto socket invisible. The large holes are used for the octal footprint.

A general purpose high quality screw set is provided with the base plate.

Teflon Audio Input / RCA Jack

Fully CNC machined part. Made from Teflon, Bronze, Silver, Gold and nothing else. These have nickel free contacts.
Each comes with four color rings, so you can color mark each connector the way you prefer.
Standard 9mm chassis hole.

This part can be used for both symmetrical (XLR) or unsymmetrical (normal RCA ) inputs. For normal mounting, the inner Teflon isolator ring is not used. So the connector is grounded to the chassis like this. If you need symmetrical inputs, you apply both isolator rings.

They feature coaxial ground connections. Engineers will love this. If you do not want to take advantage of this, there is no need of course, and you can connect only the signal wire to the center pin (same as with low cost connectors). For improved shielding however, you can consider to connect a shielded coaxial cable to it, and then you can make a nice coaxial connection without having a shield leakage at the input connector. So the outside of the coaxial cable goes around the connector. In cases like this, the outside of the cable is connected to the connector only. At the other end where it goes into the amplifier, the shield is not connected. This provides ultimate shielding, and prevents ground loops.

Special note about the gold plating of those. These connectors are little diamonds, build with ultimate contact quality in mind. When you first see them, they look not mirror-shiny, and there are sometimes questions about this. For Audio Signals it is best to have nickel free contacts, to prevent whisker noise when the contacts get old. This means the whole construction and the plating must be nickel free. Perhaps as you know, a mirror shiny gold plating results only when a nickel layer is applied underneath, and also a non-pure gold layer, is used with low gold content. Since all Yamamoto parts are nickel-free, and use pure gold only, this cannot be done on a mirror-shiny way. For best electrical results, a pure silver plating must be underneath. (Reason for this is to be found in the inter-metallic potential when two metals of different kind touch each other). This layer of pure silver However, has an opaque surface. Over the silver, several gold layers are applied, which will adopt the opaque surface as well. So please be not mislead when you first see them, and notice the plating is not done mirror -shiny! This is done in purpose, for best contact results.