Tube Sockets, Part 3. NOS sockets and parts

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NOS loctal tube socketLoctal, 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.

Picture2 - Picture3

Loctal TEFLON socket NOS. Order Number: 398-803-99

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 to force the tube in, with violence. Problem with this is, you can't feel what you are doing. It gets 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. If for some reason, the pin gets bend, this may cause a micro crack, and you can never tell ho this develops. So it may end up with glass crack, slowly leaking vacuum. This can become an issue after weeks or months. 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) would decide to wiggle the tube still, this is not ideal, but the Ediswan contacts will accept this for quite some part. This is because the pins are not locked into the contacts, but can the pin can move inside the contact in all three directions. (So vertical, or rotate, or move to or from the center) So simple this was solver mechanically, so nice it works.

The problem with Chinese Loctal sockets, they don't have this free movement. The pins are extremely tight forced into one position. When you wiggle the tube, to get it out, you are bending the pins. So you wiggle the tube 5 or 6 times, to move it out. Well then you bend all pins 5 or 6 times too. Just a little bit, but glass cracke are yes or no. There is no such thing as a little crack which doesn't matter.

Why can't you get the tube out? This is because the center contact of those is constructed too cheap, because they saved on an external spring. In addition, the center contact is much, very much too tight, and some need just violence to get a tube in for the first time. So the contact itself is the spring, but it is not made of spring material, and that causes the problem.

When inserting the tube into a Chinese LOCTAL socket, 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 are oo tiny. Sometimes a tube pin will come in between the contact and the ceramic. In that case, because of the violence you need anyway to get the tube in, you will not be able to feel this. Also you can not see it. So the poor tube pin is forced in between. Strangely, electrical contact is now 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 SHIFTS 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).

NOS, 8Pin. Order Number 399-093-778

8Pin 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 appearing now cheap on Ebay. I agree, they look much nicer than NOS, but that is all. The dimensions of those are with too much tolerance. Also the tubes itself seem to deform the the contacts, because these contacts are not made from Beryllium spring bronze. 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 as we offer here.