• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Soldering tubes directly to PCB?

I´m scetching up a layout for a tube based preamp. I would like to use a low profile enclosure with the tubes inside. But if the tubes are standing up lots of vertical space is needed.

If the tubes are soldered directly to the pcb i could get away with 75mm internal enclosure height:

15mm space between bottom plate and pcb
2mm pcb thickness
50mm tube soldered directly to pcb
3mm space to vented enclosure cover

70mm total

Using a tube socket on the pcb would increase the total height by approximately 15mm, and I don't like that.

The obvious drawback is that changing tubes is a hassle. But is there anything else?
 
I have done it in the past but I advise against it. The glass around the pin may easily get cranked due to the soldering heat. Result is air may leak in the tube. The crank may be invisible and the leak very minor.
As you mentioned tubes need to be replaced from time to time. A tube may become noisy or just sounding dull or distorting at any time.
If you want to reduce the height, mount the tubes in horizontal position. I used silicone rubber rings to hold them. Good ventilation is also important.
 
thomsva said:
I´m scetching up a layout for a tube based preamp. I would like to use a low profile enclosure with the tubes inside. But if the tubes are standing up lots of vertical space is needed.

If the tubes are soldered directly to the pcb i could get away with 75mm internal enclosure height:

15mm space between bottom plate and pcb
2mm pcb thickness
50mm tube soldered directly to pcb
3mm space to vented enclosure cover

70mm total

Using a tube socket on the pcb would increase the total height by approximately 15mm, and I don't like that.

The obvious drawback is that changing tubes is a hassle. But is there anything else?


You could use Nuvistors.....

The socket and valve cant be much more than 30mm high total....:D

The Russian wire-ended Nuvistors could be soldered straight in or wires cut and sockets used, as I have done. They are MUCH better than the NOS American things for noise and Michrophonics. Great valves. Type 6C51N is a nice medium Mu triode, and will work well (In the right CCT) down to 12V.... :bigeyes:
 
Re: Re: Soldering tubes directly to PCB?

Alastair E said:



The Russian wire-ended Nuvistors could be soldered straight in or wires cut and sockets used, as I have done. They are MUCH better than the NOS American things for noise and Michrophonics. Great valves. Type 6C51N is a nice medium Mu triode, and will work well (In the right CCT) down to 12V.... :bigeyes:

Also, a big heavy nut glued on a 6C51H (pronounced 6S51N) reduces microphonics dramatically.
 

poynton

Member
2005-03-10 11:57 pm
UK
Right-angle mount tube sockets


Angela.com


Andy
 

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Geek

Member
2004-09-08 7:17 am
Hi Tom,

Tom Bavis said:
Use separate socket pins by Mill-Max in your PCB. Will add only 1-2 mm height over tubes alone. Digi-Key stocks these - look for .040" pin size.

These can be especially useful for tubes like 10 pin or 12 pin, where sockets are hard to find.

I just measured a few minature tube pins and they're 0.85mm, ~0.034" (my caliper is in metric, eh? :D ). Looking at my Digi-Key catalog, ED5013-ND which fits .032-.046" and a 3/32" drill hole look good.

What do you think?

Cheers!
 
Geek said:
Hi Tom,



I just measured a few minature tube pins and they're 0.85mm, ~0.034" (my caliper is in metric, eh? :D ). Looking at my Digi-Key catalog, ED5013-ND which fits .032-.046" and a 3/32" drill hole look good.

What do you think?

Cheers!

When I was a teenager sockets for GU-50 were hard to find so I used pins from military plugs.
 
Another way that might gain you a bit of space is to hole cut the pcb to take the full width of the tube and have the socket mounted below using spacers. A sheet of thin insulating material glued to the chassis directly underneath the socket connections is recommended though in case the pcb is accidentally flexed downwards.
 
Thank's for all the ideas! There are several options.

I also might forget about the pcb and do a point-to point arrangement. Then I could polt the sockets to the bottom plate using pcb-spacers. Would 10mm space between socket legs and chassis be enough for 250VDC? Or is even 5mm safe?

edit: this arrangement actually does not save any significant height compared to a pcb arrangement. But minimising the space to the bottom plate would help.

Or... i could mount them on their sides.