Valve Guitar Amplifier – Pre-Amplifier Valves Compared


Guitar Amplifier Pre-Amplifier Valves Compared: There are many different guitar amp pre-amplifier valves on the market both new and old vitage stock. These can be made by a number of makes or brands and have varying performance values. It is possible with a lot of the valves to swap them around in the pre-amplifier stage of a valve guitar amplifier to change the sound and tone characteristics of the amplifier. For example you may have a 12AX7 valve , a 5751 valve, a 12AT7 valve and a 12AU7 valve. So what is the difference? These valves are all the same apart from the gain. The gain is the amount the tube boosts the input signal or amplifies it.
Here are the typical gain factors for the valves.

What does this mean? This means that the input guitar signal that passes into the tube will be boosted 100 times when using the 12AX7 tube and by only 19 times when using the 12AU7 tube.

What benefit is there to know this? Well as guitar player we are all trying to find our own sounds. Sometimes the pre-amplifier stage on an amplifier can be set during manufacture to allow a smooth or harsh output. Also, on some tube amplifiers the output can be very loud making adjustment of the output to a comfortable level. By playing about with pre-amplifier tubes you can modify the way your amplifier sounds.

First the disclaimer, make sure your amplifier is compatible with this kind of adjustment before playing around with the pre-amplifier tubes that are inside it. Some of these tubes are used in other parts of the circuitry like effects etc so just pulling them out and swapping them without making sure they are part of the pre-amplifier circuit can cause other damage to the amplifier. Read the manufacturers booklet.

Guitar Amplifier Pre-Amplifier Valves Compared
Guitar Amplifier Pre-Amplifier Valves Compared

Comparison Tests using the Yuma Gold YG-5T Practice Amplifier.

Guitar Amplifier Pre-Amplifier Valves Compared : These tests were done using the YUMAGOLD YG-5T 5W valve practice amplifier with a Les Paul guitar with humbucker pickups. The guitar volume and tone controls were set at the maximum. When buying a practice amplifier you may want to use it at home or in the studio. The problem is with a valve amplifier if you want to use this amplifier at home there is little chance of getting above 2 without the neighbours complaining. This makes sound adjustments in that type of environment difficult. Before doing any comparisons I set the volume at 5, tone at 7.

12AX7A – In the test stated above the amplifier worked good up to 8 then had some mild distortion up to 10.

5751 – by swapping out the 12AX7 with a mid-gain 5751 valve the amplifier performed the same but the overall volume was reduced.

12AT7 – by swapping out the 5751 with a mid-gain 12AT7 valve again the volume was reduced and the amplifier had a nice clean sound.

12AU7 – fitting the final low-gain 12AU7 valve resulted in a much lower output volume. Even on 10 the amplifier had a nice sound and was easy to adjust when playing at home. The amplifier also had a nice jazzy sound.

Guitar Amplifier Pre-Amplifier Valves Compared : By being able to play about with the adjust-ability of the amplifier a wide range of tones and sounds can be gained.

Valve Test Comparison Summary

Our Guitar Amplifier Pre-Amplifier Valves Compared tests have shown that by changing the preamplifier valves on your guitar amplifier you can adjust the overall sound and create your own sound that you are comfortable with. Taking out a low gain and adding a high gain will increase volume, distortion and break up. Taking out a high gain and adding a low gain will reduce volume and make the amplifier cleaner sounding and easy to adjust. We can supply a set of pre-amplifier valves for you to test the settings in your amplifier. Valves are sold online at our web store a single items.

Buy YUMAGOLD guitar amplifier valves in our web store where you will find single tubes and matched sets available at reasonable prices. Our valves are specially selected for performance and branded with the YUMAGOLD brand. Our supplier has a very long history and excellent reputation for manufacturing high quality replacement valves for both guitar and other types of amplifier. Our supplier also sells rebranded valves to some of the best known brands in the guitar amplifier field.