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A customer that purchased my 12AX7 vacuum tube breadboard adapters, years ago, recently sent me an image of how he is using it. He's doing some radio / audio circuits. We won't hold the radio part against him!

No matter what the application is it's always great to see these old PCB designs in action.  Many thanks for permission to share your image.

If you are interested in vacuum tube breadboard adapters just leave a comment and I will get back with you. Quantities are starting to get scarce but I still have some left from my original PCB run back in 2007.

Thanks for reading,



So here's my direct box I've been working on for some time now.

At the time of this image I didn't have the battery circuit working yet. This design operates on +48V and +9V and can fully isolate both system grounds. Power rails are +/-18VDC on a 9V battery and +/- 13VDC on phantom power.

The features are really simple. Input, Thru, Output, GND Lift and Power Select.
The 9V battery is secured to the PCB with a battery holder.

The battery holder is held in place using broaching clinch nuts made for PCB material. I get mine from Self Clinch You can buy direct from the web site and it's a fairly painless process.

I used 4-40 nuts, part number TR-KFS2-440, for the final design. The nuts in the images here are the 6-32 size which are way too big.

They can be installed with an arbor press or a hammer if you are careful. If you are going to hammer them make sure you do it before you mount any parts to the PCB. Below is the bottom of the PCB.

Here's a view at the top of the PCB. Notice how the fiberglass gets disturbed after installation.

That's it for now. I will post more soon.

Thanks for reading,


Rupert Neve Direct Box

I purchased a Neve RNDI as a reference for a custom D.I. that I am working on.

The Neve box operates on +48V phantom power only. (no battery option available)

It's really easy to use.  Plug "IN", Set to Instrument, Connect XLR cable and hit +48V. Done.

There is one giant Neve transformer inside that gives this box that "transformer sound".

A single input amplifier drives the transformer. (small SMT transistors at bottom right of transformer)

The box sounds really good and has a higher input impedance than you get from using a transformer alone.

If you are looking for a quality D.I., don't need battery power, and have +48V phantom power available, you may want to give the Neve RNDI a try. I think you will be impressed.

Thanks for reading,