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The IN-9 Nixielyzer is an analog audio spectrum analyzer, based around an analog bandpass chip. It offers the display of six selective audio bands: 63 Hz, 150 Hz, 330 Hz, 1 kHz, 3.3 kHz and 10 kHz.

As a feature, you can mix the signal of a build in microphone, to use the IN-9 Nixielyzer as a stand-alone device when no audio source is connected).

The IN-9 Nixielyzer operates with six IN-9 Nixie Bargraph tubess and has two RCA stereo in- and outputs (for easy daisy chaining the device within an existing audio path) and also two 1/8" TRS jacks for simple connecting your MP3 player, mobile phone plus headphone for listening etc.

Both signals (RCA and 1/8" TRS are only internal mixed via an electronic zero ohms node and do not affect each other.

The IN-9 Nixielyzer uses no digital signal processor or FFT (Fast Fourier Transformation); so the display is stepless and fully in realtime.
Furthermore a modified dbx compandor ciruity was introduced to enhance the dislayed dynamic range.

Video Review from "Techmoan"

Assembling the kit and circuit description from "youtuuba"

What is an audio spectrum analyzer?

You surely know a VU meter, which shows the level of an audio signal, often build with LEDs on the DIY market.
The IN-9 Nixielyzer now separates this audio signal into six selective bands and show their special audio level within this frequency range:

• 63 Hz = Low Bass (e.g. Bassdrum)
• 150 Hz= Mid Bass (e.g. Bassguitar)
• 330 Hz = Low Mid (near concert pitch of the most musican instruments)
•1 kHz = Mid of voice frequency (e.g. the "beep" sound for indecent words in interviews)
• 3.3 kHz = Presence (e.g. "sch" in the word Schedule or the imitated sound of a steam locomotive)
• 10 kHz = Heights (e.g. "sssss")

And as an absolute unique feature, the IN-9 Nixielyzer displays the level not on "ordinary" LED display or VFD display or on a computer screen or even in an App of your mobile phone but on six IN-9 Nixie Bargraph tubes made in the end of the 80's in USSR as a surplus.
If you order the DIY kit version, you'll get
PCBs with double sided silk screen and pre-assembled and soldered SMD parts
All extra necessary electronic components
All necessary mounting hardware
Complete enclosure with all necessary frames (silvery or coppery)
15 VDC wall mart power supply with EU mains incl. adaptors for US/GB/AU (if necessary) is included
Black anodized Alumnium frame
Set of IN-9 tubes (Neon or Argon)


  • 15 VDC power supply included
  • Very low self generated heat
  • Stereo RCA in- and outputs for easy daisy chaining into an existing audio path.
  • Two 1/8" TRS stereo inputs as an alternative for MP3 player, mobile phone, headphone etc.
  • Selectable audio channel (right / both / left) for display.
  • Build-in microphone signal can be mixed.
  • 63 Hz, 150 Hz, 330 Hz, 1 kHz, 3.3 kHz and 10 kHz audio spectrum level are displayed.
  • Dimensions (W x D x H): ca. 135 x 95 x 160 mm incl. tubes


Pre-assembled Nixielyzer (can be finalized without soldering skills) incl. power supply and worldwide DHL shipping for 356 EUR - please click on the logo

Please drop me a note about your address.

Shipping costs
Shipping and handling costs are already icluded in the product price. The prices for shipping within EU includes the German VAT.
Import duties, taxes etc. are not included. These charges are the buyer's responsibility.
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