Nixie tube amplifier project - unfinished - help!


My name is Kate and I'm in the Denver area. I was directed to this group by Karl at The Music Room. 

My late husband, Adam, was an electrical engineer and audiophile. As a passion project, he was building his own nixie tube amplifier for our stereo system. But, almost two years ago, he had a heart attack and died suddenly before he was able to finish the project. It was very near completion; I saw him install the tubes, power it on and watched the tubes glow - it worked! He sourced all of the parts himself and designed it in CAD. I have all of the parts and engineering diagrams, but they might as well be in Chinese to me. There was some final tinkering and assembly that he needed to do, along with building a case to house it.

I was wondering if anyone might be interested in trying to finish a project like this? I am getting ready to move out of my house at the end of July and need to do something with the amplifier - but the thought of just throwing it in the garbage kills me. It's also insanely heavy (transformers, I think), so it would have to go to someone locally.

Let me know if you have any interest or want more information. You can email me about this as well at




Nixie tubes do not amplify. They display numbers and are the old school version of what was around before LEDs were used to display numbers (like in old digital alarm clocks). So a nixie tube amplifier doesn't seem to be a thing- could it be some other kind of tube?
@atmasphere : You are correct!  Its got to be some other tube type! I am curious and hope the OP will respond!
Post removed 
Hi all! 

I'm sorry that I don't understand this better. I am absolutely certain that this involves Nixie tubes. I don't see a way to post photos in this forum or else I would post some pictures of the project and the diagrams. 

@roberjerman did you send me an email? I don't see anything in my gmail. I logged into Hangouts and also didn't see anything in there. 

Thanks for your responses!

Its design may use VDF tubes, which are often incorrectly described as being a Nixie tube.

Both are "display" type tubes, but as far as I gather VDF’s can be used in gain stages.

I wonder if he was using a Nu-Tube from Korg? That tube is based on VDF concepts. IIRC Nelson Pass makes a kit preamp using that tube.

At any rate this does not sound like it would be all that challenging to sort out.

The tubes that I can see/find easily are labeled "Philco 7P" and "Sylvania 6DQ4." Is there any way to post pictures on this forum? Are you local and by chance want to come check it out?
I sent a message to you on Google Hangouts using your email address. I will try again! That way you can send me some pictures! I am always curious to see what someone's building!
Think I transposed the letters which should be VFD for "vacuum fluorescent display".


The tubes that I can see/find easily are labeled "Philco 7P" and "Sylvania 6DQ4."
@kjmelvin    The Sylvania tube is a rectifier in the power supply and does not amplify. The 7P is not the tube type of the Phillips tube- that seems to be a house number. But it suggests an older tube! Look elsewhere on that tube to see if you can find the number. Its often etched into the glass on the side.
I found the other box of actual glowing tubes! I can't put a picture here, but they are etched into the glass and say "C7K" and "38" in a blue diamond shape. I'll keep digging. 
@kjmelvin   I run a small tube amp manufacturing company called Atma-Sphere. If you want, send me a photo to my email address. You can find that on the contact page of our website

Maybe we can get to the bottom of this. If you have the schematic diagrams and parts, I'm sure it would not be hard to sort this out. I have to admit I'm curious what the VFD tube is doing in a project like this.