JJ 5751 Preamp Vacuum Tube

10 Reviews
SKU: JJ-5751

Availability: Usually ships within 24 hours.

USD $‎21.95
The JJ 5751 vacuum tube is often used in place of a 12AX7. They only have 70% of the gain of a 12AX7 preamp tube, and are often used to quiet down guitar amps that have too much gain. You can learn more about this on our tone tweak info page.

Other JJ Electronics tubes12AX7 Types

Additional Information and Downloads

12AX7 Tube Review

Tube Matching Information:
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JJ 5751 Datasheet (PDF)

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Warranty Information and Return Policy

Warranty Period: 3 months

All our tubes are guaranteed for 3 months from the date of purchase. (Any exceptions will be noted on that tube's Warranty tab)

If you receive a tube that does not perform to the manufacturer's specifications, please do the following:

- contact us to get a return authorization
- return it via regular mail within 90 days from when we shipped it, and we will provide an exchange or refund of the full purchase price of the tube.

Returns not related to warranty or defect will be considered at our discretion, and are subject to a 15% restocking fee.

We can not accept returns that don't have an authorization, are past 3 month, or are returned improperly.

These guidelines may be updated without notice.

Ratings & Reviews

10 reviews

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JJ 5751 | JJ 5751


I've never tried a 5751, so I purchased one of JJ-5751 tubes to see what sound I could get, and how it would effect my amp. After breaking it in for several hours I put a Blackburn Mullard in and played for around a hour, then replaced that with the JJ and out of all the 12ax7s that I own this tube brought out the ultimate sound for my ears! Everything was perfectly EQed with a presence of rich harmonics without a loss of bass, mids, and just the way the highs came through I found this very puzzling, and had me in disbelief in comparison with RCA, GE, Nos Mullards and other modern 12AX7s!!!! In V1 I have found the best tube currently available for my amplifiers, now I can sit on my treasure of NOS tubes and play this 5751 that should last a while with it's robust build. If you purchase this tube request balanced, and matched at 100/100 as I do with all my tubes, you wont find a better tube being currently made at a incredible price! Rock and Roll, Eddy!

JJ 5751 | Slotted in V1 in all my amps


This JJ-5751 tube is a must have in P1 for me. Along with that 30% drop in gain, the frequencies that this tube brings out are simply delightful. For me it's a must have in V1 for taming shrillness and boominess and to give me more clean headroom.
If you're on the fence or feel that your tone could be smoothed out a little, pick up one of these tubes and give it a try before ditching your amp. It's worth trying.

JJ 5751 | I almost got rid of my DSL1HR (non-50th Anniversary)


After the initial honeymoon, I came to the realization the Ultra-Gain channel on the DSL1H is just that. 0-to-UltraGain, nothing in between. Fine if that's your thing, but I was left wanting for more crunch.
And then I swapped V1 for this guy, JJ-5751 vacuum tube. Cue-in the celestial light beaming down on the half stack. Now we're playing!
It's essentially transformed the dirt channel. More options, more harmonics, musicality -favorite cliché here-. I can now dial almost any filth from light OD, to crunch, to grind, to full-bore. Still more gain than I usually need, past 3 O'clock, but I'm glad that option is still there.
I did lose a smidge of power in the operation, but this is my desktop/home/bedroom-studio amp, and it's way too forking loud for quiet practice as it is. So, in my opinion, for the purpose of the amp, this is no loss.
Seriously, if you have a DSL1 and read this: do it. Go. You'll be buying yourself a brand new amp, AC/DC in a mini-head for 20$ CAD. Go. Add-it to your cart...

JJ 5751 | Amazing tube for guitar amps


I love this JJ-5751 tube. I use two of them in my Fender Blues Deluxe RI, in V2 and V3 (gain matched for V3). (I love the EH 12AY7 for V1)
Compared to 'normal' 12AX7s they have about 30% less gain, which translates to more headroom. I find them very dynamic/responsive to picking.
I love the EQ of this specific tube. It has full, rich mids, sparkly treble, and a good amount of bass but not flubby. Really keeps all of your guitar there and gives you a soundspace to work with.
I would totally try these in an audio amplifier as well but I am not experienced in that realm.

Highly recommended by me. If your tube amp is a bit too loud or getting fizzy with the gain up, try these.

Helped tame my Blackstar HT-5RH


My Blackstar HT-5RH went from no gain to distortion with barely a turn of the knob. Not so good for getting that classic rock crunch. So I replaced the stock 12AX7 preamp tube with the JJ 5751 and it made it so I have from a light crunch to heavier crunch in between 7-9 o'clock for more of that classic rock feel while retaining the tone and character of the amp. It may have lost some treble after 12 o'clock, but by that point you still have all the gain you could need.