How long do 12AT7 tubes last?
about 10,000 hours
Small signal tubes like a 12AX7 or 6922 will work well on average for about 10,000 hours.
What do bad preamp tubes sound like?
A bad preamp tube will become very noisy and produce hiss, crackle, and pop sounds, or create volume drops or loss. In some rare conditions, the tube can also lose its vacuum and fail completely. Bad preamp tube symptoms can lead you to the faulty one if you know what to look for.
How do you know when your power tubes need replacing?
A: These are the most common signs that tubes need replacement:
- Excessive noise (hiss, hum) including squealing or microphonic tubes.
- Loss of high end.
- A muddy bottom end; Sounds like there is too much bass and note clarity is lost.
- Erratic changes in the overall volume.
- The amp doesn’t work!
How often should preamp tubes be replaced?
2 – 3 years
Preamp Tubes are generally at their best 2 – 3 years. Power Tubes are generally at their best 1 – 1.5 years. Rectifier Tubes are generally at their best 3 – 5+ years.
What do you think about the Mullard 4024?
The 4024 is a later 1980s tube as you know. Quite linear (maybe even bright) in its response… A fine phase inverter, but I’ve lately been digging the earlier Blackburn 1960s Mullard AT7s (ECC81) for the PI spot in my Fenders. Rounder, mid-range bump with more harmonic content… Looking for more? Check out top product discussions on
What is the difference between a cv4024 and a 654?
The CV4024 is more common, and less expensive. Take note: there are ’60s 654 types, made in Mitcham, that are not like the last production (’70s/’80s) version, but are more akin to all other 12AT7 (tonally thin, bright). The last-production CV4024 really stands apart from the rest, if you like that fatter character.
Where can I find the pin protector for the cv4024?
Look for the white military boxed CV4024 with the “KQDD/K” and the black plastic pin protector. There are many possible sources – I believe TGP dealers Doug’s Tubes and KCA NOS Tubes both carry these at a reasonable price, for example.