Tube Sockets, Part 3. NOS sockets and parts

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NOS loctal tube socket

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Loctal TEFLON socket NOS
Order Number

Loctal, TEFLON Socket. Silver plated contacts. Made by Ediswan, England. Originally packed in pair boxes, or single, originally air sealed packs. Pricing is for one single socket.

Dimensions drawing

Together with the adjustable (!) socket dampers, this results in a very nice combination. The sockets contacts are silver plated. The solder contacts are tin plated.

We made this air ventialtion plate specially for the Ediswan sockets. Though painted black, underneath the paint is a copper screen, giving best possible screening to the sockets. First, loctal sockets are very nice for a special reason: They have a grounded center pin, which connects to the metal base of the tube. So even when glass tubes, we have this metal base still. It shieldsl the tube bottom reasonably we, where the hum-senstive grid connection is. When steel tubes, the whole tube outisde case becomes connected to this, which works even better. This center pin has an electrical connection at the loctal socket! Connect this to one of the mounting screws. This will connect it to the copper shield of the base plate. (It is underneath the black paint) A second wire is connected from the center pin to the chassis. This will ground the whole tube construction so excellent, much better than normal octal tubes.

In case isolation mounting devices are used, such as rubber distance holders, we recommend connect the center pin to the amplifier chassis, to achieve best possible screening still.


These Ediswan sockets have normal screw distance, dimensions, just the diameter of the Teflon part is 3mm smaller. So instead of regular 30mm, you need 27mm.

Dimensions and material:

Black plate outside: 59 x 59mm
Mounting holes, center distance 48mm.
Mounting holes of socket, center distance 38mm
Glass fiber Epoxy, black painted
Sides and holes: shiny Metal color.

WARNING: NOS loctal tube socketChinese sockets often damage the LOCTAL tubes. The center contact of those is so stiff and terrible, you have no other choice than press in the tube with some violence. It gets even worse when you want to remove the tube. You can not just pull the tube out straight, but you need to wiggle the tube far too much. By itself, the force on the center pin is no problem, but a problem comes with the tube pins. These go directly trough the glass, and have no protection against side force. This can cause micro cracks, and you will know from glass cracks, these can (and will) grow. So it may end up with a micro crack, eventually leaking vacuum. WIth those Ediswan sockets, you don't have this problen. First of all you can pull the tube out vertically without wiggling. Second, in case you (or your customer) do wiggle the tube, it is not ideal, but the Ediswan contacts will accept this for some part, because the pins are not locked into the contacts, but can tilt the contact in the direction of the socket center, while wiggling. .

The problem with Chinese Loctal socksts, is the exceptional, almost crazy force it needs to press a tube inside. This is because the center contact of those is constructed too cheap, with little quality control, and they saved on an external spring. So the contact itself is the spring, and that causes this problem. Yo can not feel if a tube pin is not exactly opposite to the pin contact itself. For this look at the hand made drawing above here. That is because the hole in the ceramic is too large, and the pin contacts too tiny. Sometimes a tube pin will come in between the contact and the ceramic. Then because of the heavy force you need anyway, you will not be able to feel this, and also you can not see it. So the poor tube pin is forced in between. Strangely enough, this will even work. Electrical contact is even good. Only the pin is deformed, and so is the socket contact. Any other tube which is put into this (now damaged socket) will suffer the same problem. You probably only notice because the tube has a pin which is bend, when you pull it out. Often this is not recognized as a socket problem. So the pin is straightened, it works a few times, until it happens again. This ends with the pin sometimes being trapped, and people need use a screw driver to force the tube out, but before all of that, the glass crack has already developed.

NOS loctal tube socket This wiggling will only SHIFT the pins in the USA and European sockets (see the drawing). I never thought this was important, until we sold many Loctal tubes like C3g and C3m. Specially with the Telefunken C3g-S which cost more than 100 Euro for one, this is not worth it to save on the sockets, and risk the tube.

Most other Chinese sockets are fine, but not the Loctal (and also not the Au-8, see next socket).

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NOS, 8Pin
Order Number
399-093-778 Pin Au Socket for AD1, AZ1, AZ4, etc. Bakelite socket, black material. We bought this NOS lot of appr 800 pcs in 1985, and there was no Chinese production at that time.

WARNING: We must warm here very strong against those nice looking gold plated Chinese sockets appear now cheap on Ebay since a few years. I agree, they look beautiful, but that is all. The dimensions of those are with too much tolerance. Also the tubes itself seem to the the contacts, because these contacts are not made from Beryllium of high quality spring bronze, but made from some cheap metal. After a while, the contacts get loose, and sometimes even fall inside. note, a loose grid contact can damage a tube totally, and a loose plate contact can damage the output transformer already at the first crack sound you hear. Better forget about the "gold", it is fake gold anyway, and use real NOS sockets.

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