A healthy glass neon sign is silent and steady. Modern electronic transformers do not hum, and a good tube does not flicker.
If yours does either, it is telling you something: usually an aging transformer, a loose connection, or a failing electrode. None of those get better on their own.
Where a hum comes from
The tube itself is silent. Any noise is the transformer, and which kind of transformer decides whether you hear anything at all.
| Transformer | Sound | Notes |
|---|---|---|
| Modern electronic | Silent | What we supply. Lighter, cooler, quieter |
| Old iron core | An audible mains hum | Common in vintage and salvaged signs |
| Any transformer, failing | Buzzing, crackling | Switch it off and have it looked at |
Why a tube flickers
Flicker is more diagnostic than hum, because a healthy glass sign should light cleanly and hold steady.
- ✓ A brief flicker at switch on is normal, especially in the cold. Glass neon takes a moment to strike.
- ✗ Persistent flicker usually means a loose connection or an aging electrode.
- ✗ One section dark while the rest lights points to a break or a failed section rather than a power problem.
- ✗ Flicker that worsens over weeks is a tube approaching end of life or a transformer on its way out.
How LED neon compares
LED neon is silent and does not flicker, because there is no transformer under load and no gas to strike. It lights instantly, including in the cold, and runs on 12V. That is a genuine practical advantage and we are happy to say so.
What it does not have is the depth of color and the slight irregularity of hand bent glass, which is exactly what people who want real glass are buying. The two are different products rather than better and worse versions of one.
If you are weighing them up, the full comparison is here, and we make both.
Do not accept persistent flicker on a glass sign as character. Hum from an old iron core transformer, fine, that is the technology. Flicker is a fault, and on high voltage equipment a fault worth attending to promptly rather than eventually.
Frequently asked questions
Do real glass neon signs hum?
Modern signs with electronic transformers are silent. The audible hum people associate with neon comes from old iron core transformers, which are common in vintage and salvaged signs. An irregular buzz or crackle from any transformer is a fault rather than a characteristic.
Why does my glass neon sign flicker?
A brief flicker as it strikes, particularly in the cold, is normal. Persistent flicker usually means a loose connection or an aging electrode, and flicker that worsens over weeks suggests a tube near end of life or a failing transformer. None of those resolve on their own.
Is a buzzing neon sign dangerous?
Glass neon runs on high voltage, so a sign that buzzes, crackles, smells hot or flickers persistently should be switched off at the wall and looked at by someone who works on neon. This is not a category for do it yourself investigation.
Does LED neon hum or flicker?
No. It runs on 12V, has no gas to strike and no transformer under load, so it is silent and lights instantly, including in the cold. That is a real practical advantage over glass, though it does not reproduce the depth of color of a hand bent tube.
Part of my sign is dark. Is that the transformer?
More likely a break or a failed section, since a transformer problem tends to affect the whole sign rather than one part of it. Either way it is a repair job on high voltage equipment, so switch it off and get it looked at.
We have made neon since 1998, and we still make it ourselves. If something here does not answer your question, ask us.
