Vacuum Tube - 5751, JJ Electronics

Vacuum Tube - 5751, JJ Electronics

JJ Electronics
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The JJ Electronic 5751 is a dual triode that can be used in place of most 12AX7 circuits. The rugged build of this tube and reduced gain (30% less than a 12AX7) can improve headroom and give better control in high gain stages allowing users to more easily dial in sweet spots. The JJ 5751 features a smooth and balanced tone and a detailed response with low noise and low microphonics.

Item ID:
JJ Electronics Part Number:
JJ Electronics
Body Height49.2 mm
Filament Current (If)350 / 175 mA
Filament Voltage (Uf)6.3 / 12.6 V
Gain (μ)70
Grid Voltage (Ug)≥ -50 V, -1 V typical
Grid capacitance (cg1)1.6 pF
Grid to Plate Capacitance (ca/g)1.7 pF
Internal Resistance (Ri)58 kΩ
Item Diameter22 mm
Item Height56.3 mm
Plate Capacitance (ca)0.33 pF
Plate Current (Ia)0.8 mA
Plate Dissipation (Wa)≤ 1 W
Plate Voltage (Ua)≤ 300 V, 100 V typical
Transconductance (S)1.2 mA/V
Packaging Information
Packaging Dimensions0.9 in. × 0.9 in. × 2.3 in.
Weight (Packaging)0.05 lbs.

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Specifications, Files, and Documents

PDF: Specification Sheet Specification Sheet475.34 KB
Questions? Contact us at [email protected], or give us a call at 480-820-5411

Product Reviews

4.86 out of 5 based on 7 reviews
Lesleo - May 20th, 2022
5 out of 5

In the vast majority of applications (most, not all) I've used the 5751 ... that's as a replacement for a 12ax7 ... they have provided a "smoother" warmer tone ... little if any volume reduction, better balance of bass-mid-treble. elimination of "ice-pick" highs.
One standout success was the Crate VC(vintage club)20 combo, a "sleeper" grab 'n go blues/amp that flies under the radar. 2 - EL84, 3-12ax7 The amp was designed to run scorching hot, with the result that at above 5 on the volume it starts squealing. Replaced all 3 12ax7 with 5751 and tonal nirvana. Will continue rolling some in more of the collection ... Top Hat, Louis Electric, Fuchs, Morgan and watch for similar tonal enhancements !! AES has terrific customer service ... supply, pricing, delivery A++

Rodney Hutchins - February 15th, 2022
5 out of 5

I installed this JJ 5751 in V2 of my 1965 Fender Deluxe Reverb Amp replacing the 12ax7. I was told/read that it will give me a little more headroom and better tone. I haven’t had a chance to try it yet. I also pulled V1 12ax7 and left it out, I never use that channel anyway. I sure hope it make this great little amp even better.

Bill Sheppard - January 9th, 2022
5 out of 5

Replaced the China tubes with 2 JJ 5751 Tubes. In my Fender Greta 2.5 watt practice amp. It had a 12ax7 pre-amp and a 12AT7 in the power section. The 2 5751s changed the whole dynamics of the amp! Clear, chimey, Stratocaster, with much more headroom. Also sounds great with a Fuzz Face, both Germanium and Silicon. The guitar just sings, I'm so pleased!

TWANG - April 16th, 2020
5 out of 5

5751 by JJ I like these in V1. I did this with two amplifiers. (sent one of them in the pic.) one was a marshall clone and the other was a fendery design from a friend. a little less power, but all the tone. nice for cleaner headroom. and I think a bit more control on the dirt, too. good stuff!

MarkVegas - July 12th, 2019
5 out of 5

Great tube ! Fast Shipping !

will pierce - August 7th, 2015
5 out of 5

I was looking to change the gain and tone of my old Marshall XLS's. The tubes worked as desired. The shipping and price were also reasonable. I will be a return customer.

Carvin clown - February 23rd, 2015
4 out of 5

I am using this JJ 5751, in the V2 position in my Carvin X100b from around 1994. I believe this is the second gain stage. In the V1 position, I have the Tungsoll 12ax7. Since I installed the tubes at the same time, my review will be somewhat biased (pun intended), with that being said, my overall impression is that the amp has a more balanced sound across the frequencies, with a nice bit of texture and punch, smoothly added in. The tubes I had before were a GE 12ax7 from around the mid 60's and a EH 12ax7. Whether I'm using the clean channel, or the overdrive channel- including the boost, the overall improvement, while not awe inspiring, is noticeable and makes for a stronger, smoother, and more enjoyable playing experience. The noise level did not increase, and that is noteworthy because the GE tube was very quiet, compared to others I have tried. I would think that it would be hard to go wrong with this combination.