The 12AY7 valve versus the ECC83 valve.
The 12AY7 valve (also known as the 6072) is a 9-pin tube. There are two valves in one glass envelope. It is what is called a ‘double triode’. It was designed as a low noise tube and was developed before the ECC83 (12AX7)
The application for the 12AY7 is usually an audio preamplifier. This valve is also sometimes found in the phase-inverter position. The 12AY7 was used in the Fender Tweed amplifiers such as the Deluxe (5E3), high power Twin (5F8A), Low Power Twin (5E8A), Tremolux (5G9), Super (5F4), Pro (5E5A), Bassman (5F6A), and Bandmaster (5E7).
Why Use the 12AY7 valve?
The most common reason for using a 12AY7 instead of the more common 12AX7 (ECC83) is that the 12AY7 has 45% of the gain of the 12AX7. So about half, or 6dB in technical terms.
Using The 12AY7 to Tame The Gain of Your Guitar Amplifier.
Some guitar amplifiers (particularly Fender Blues DeLuxe, Blues DeVille etc) have WAY too much gain on the front end for many people’s tastes. I often hear the complaint that he guitarists can’t get the volume off 1 or 2 before being deafened!
If this is you, then there is a simple solution. Just swap V1 for a 12AY87. Your V1 will be a 12AX7 (ECC83) with a gain of 100. Swap it for a 12AY7 (gain 45) and suddenly you can get the volume control off the bottom rung! You’ll also notice less noise from the amplifier. Some say the 12AY7 is also ‘warmer’ with more bottom end, but these things can be very subjective.
When to Buy a 12AY7
There are usually only two reasons:
- To replace an existing 12AY7
- To reduce the front end gain of an overly loud amplifier. Substituting a 12AY7 for a 12AX7 (ECC83) will approximately halve the gain.
If you are buying a 12AY7 for gain reduction reasons, be aware that you may or may not like the final result. It’s a question of trying and seeing.