Best Tubes For Fender Blues Jr

One of the favorite ‘mods’ for the Fender Blues Jr is changing its tubes. Whether to improve its tone, to get more gains or simply replaced worn out tubes, changing tubes will definitely impact the sound you are getting.

In the Fender Blues Jr amp, there are 5 tubes you can swap out and they labelled V1 to 5. Changing V1 has the most impact on tone quality.

The best value for money V1 tubes for fender blues is the 12AX7 tubes from
Electro-Harmonix. You will be getting a better bottom as well as a smooth and rounded top.

The next set of tube changes you might want to make is to the V4 and V5. For these I recommend the JJ El84s. The prices are pretty affordable without sacrificing the audio quality. They are also hard working tubes that give a solid output.


Why I choose the Electro-Harmonix 12AX7 vs Sovtek vs Tung Sol

The Electro Harmonix has the following differences over the stock Sovtek 12AX7.

  • Has better lows as you can hear the bottom more clearly.
  • Has a crunchy sound that is similar to the Sovtek but with a smoother top
  • However, the EH has a humming note that some might dislike. It is not obvious except to those who really listen to every single note.

Other 12AX7 tubes to consider

Sovtek 12AX7: These are the default tubes and there is nothing wrong with these. They work hard and produce a clearer and bright chimp. However, most people usually find faults with them.

I prefer EH versions as they are darker and have a stronger midrange. Some of you might prefer the brighter tone of the Sovtek, in which case there is no need to replace anything.

Tung Sol 12AX7: This tube has the brightest articulation among the 3 12AX& tubes covered here, especially when compared against the Sovtek. Most Fender fans I know love brighter tones so this is a good alternative if you want the Fender tone. In addition, the Tung Sol also has a high end complexity whereas Sovtek is more straight forward.

Compared to the EH, I feel Tung Sol’s top is less smooth. Not saying the Tung Sol has a bad top but just not as sweet

The downside is that volume wise, it is more quieter than Sovtek and EH.


Why I choose JJ EL84 vs Mullard vs Gold Lion

The EL84 won me over with its combination of affordable pricing and quality of sound. Specifically,

  • The tones are fuller especially to mid to low range. It is very noticeable especially if you have good speakers or headphones.
  • They are pretty long lasting tubes, at least for the ones I have purchased. They usually last me between 9 months to 1 year, depending on the frequency which I played.
  • They take less time to be seasoned.

Other EL84 tubes to consider

Mullard EL84: This is a nice alternative to JJ but is about $15 more than JJ. If you are a blues player, you will appreciate this tube as you can get into distortion much easier.

When in distortion, its overdrives sounds creamier than other tubes.

However, the mullard EL84 also has less headroom so some players might not appreciate it.

In terms of life span, it seems JJ can last longer from the forums I read but I can’t vouch for that personally.

Genalex Gold Lion EL84: This is the most expensive option but you get more refined sound than the JJ. The difference is pretty subtle but it is there if you listen hard enough. Overdrives are also clearer when compared to Mullard or JJ.

However, I don’t find the price difference to justify for these subtle increase in audio quality. The build quality, doesn’t seem to reflect the additional cash outlay. If you have the spare dough, this is worth a consideration.


Understanding the Fender Blues Jr tubes layout

If you are new to changing tubes in the Fender Blues amp, this section is for you.

To start off, know that there are 5 types of tubes, labelled form V1 to V5 (Note: you can see the labels at the back of the amp) :

  • V1 – preamplifier
  • V2 – recovers lost signals and has the least impact. Don’t bother changing this
  • V3 – it copies the signal and directs it to the output tubes. Look at them as traffic controllers. Not much impact either.
  • V4 and V5 – output tubes. These will be the more important tubes to change after V1. They come in a pair and you need to change both.

The most drastic difference you will hear is from changing V1, which is the preamplifier. The stock V1 tube model is the grove 12AX7. You can either replace it with other brand’s 12AX7 or you can switch to 5751.

The difference between 12AX7 and 5751 is the amount of distortion you can can get.

For 12AX7, the sounds starts to distort after the volume knob goes beyond 4.

For 5751, it only starts after the volume knob reaches 5.

In terms of tone, the 5751 offer a warmer tone so it is ideal for players who like jazz, blues, soft rock etc. If you are more into metal, heavy rock etc, stay ith the 12AX7.

The next set of tubes you can change are the V4 and V6. Changing them will NOT lead to a drastic increase in audio quality, although they can help to improve the mids of the Fender amp.



Choosing the right tubes to fit your preferred tone and playing style is always tricky. I provided some recommendations that cater to different needs. Hopefully, this will help you out in picking out the correct tubes.

Personally, I prefer EH for my V1 and JJ for my V4 and V5. This set up gives me a good balance in mid, high and low. Compared to the original set up, I find my sound to be richer and smoother.

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