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A 5751 is a lower-gain, dual-triode alternative to a 12AX7 only where the amplifier designer permits it; it is not a universal replacement and it is never a power-tube substitute. Modern production is limited chiefly to JJ Electronic and Tung-Sol reissues, while the rest of the market is tested old-stock (NOS) inventory whose construction, balance and remaining life vary by seller. Check the amplifier schematic or maker before changing a position, especially phase-inverter and reverb-driver sockets. Unplugged tube amplifiers can retain dangerous high voltage: if you are not qualified to work inside an amp, have a technician assess compatibility and perform any internal service.
| # | Product | Price | Where to buy |
|---|---|---|---|
| 1 | JJ Electronic 5751 | $25–$45 | Amazon · eBay |
| 2 | Tung-Sol 5751 Reissue | $55–$80 | Amazon · eBay |
| 3 | Tung-Sol 5751 Gold Pins | $70–$95 | Amazon · eBay |
| 4 | GE 5751 Five-Star Double-Mica NOS | $30–$55 | Amazon · eBay |
| 5 | Raytheon 5751 Windmill Getter NOS | $50–$80 | Amazon · eBay |
| 6 | RCA 5751 Command Series NOS | $65–$95 | Amazon |
| 7 | Sylvania 5751 Gold Brand NOS | $35–$65 | Amazon · eBay |
| 8 | CBS/Hytron 5751 Triple-Mica NOS | $25–$50 | Amazon · eBay |
| 9 | Siemens 5751 NOS | $45–$75 | Amazon · eBay |
| 10 | JAN Philips/Sylvania 5751 NOS | $70–$90 | Amazon · eBay |
The picks, in detail
JJ Electronic 5751
A current-production Slovak 5751 for an amp position explicitly approved for a lower-gain 12AX7-family tube. It is the practical choice when new manufacture and a dealer warranty matter more than vintage construction.
- current-production JJ Electronic double triode
- 5751 pinout format
- sold individually and in tested/matched dealer selections
- New-production supply is more repeatable than one-off NOS listings
- Usually the lowest-risk place to start when a compatible amp needs a 5751
- A 5751 changes gain structure versus a 12AX7; it is not automatically suitable for every socket
Tung-Sol 5751 Reissue
A current Tung-Sol-branded 5751 sold by Electro-Harmonix/New Sensor. Use it only in a manufacturer-approved 5751-compatible preamp position, and buy a tested sample for a sensitive first-gain stage.
- current Tung-Sol reissue
- miniature twin-triode 5751
- EHX listed price $75.60 per box
- Current product with published maker technical documentation
- Available through specialist tube dealers
- Costs more than many standard 12AX7 options
Tung-Sol 5751 Gold Pins
The gold-pin version of the current Tung-Sol 5751 is a separately sold reissue variant. It belongs in the same compatibility conversation as the standard Tung-Sol 5751, not in an arbitrary power-tube socket.
- current Tung-Sol Gold Pins variant
- 5751 twin-triode format
- EHX listed price $86.40 per box
- Distinct current-production option for buyers seeking the gold-pin version
- Manufacturer publishes a dedicated 5751 Gold technical sheet
- Higher price does not remove the need to confirm socket suitability
GE 5751 Five-Star Double-Mica NOS
A tested NOS General Electric Five-Star, double-mica 5751 for buyers who want a specific vintage construction. Treat the actual test results, microphonics screening and return policy as part of the product because this is finite old stock.
- NOS General Electric Five-Star marking
- double-mica construction
- listed at $35 by VacuumTubes.net
- Specific construction is identified rather than sold as an anonymous 5751
- Vintage option with a comparatively modest observed listing price
- Availability and measured condition vary tube by tube
Raytheon 5751 Windmill Getter NOS
A NOS Raytheon 5751 identified by its windmill getter construction. It is a specialist old-stock choice, so request test data and avoid assuming that two seller listings are electrically matched.
- NOS Raytheon 5751
- windmill getter construction
- listed at $60 by VacuumTubes.net
- The construction is explicitly identified for collectors and tube rollers
- A distinct Raytheon option rather than a relabelled generic listing
- Vintage stock commands a premium and can be scarce
RCA 5751 Command Series NOS
A NOS RCA Command Series 5751 for a buyer deliberately seeking that marked vintage variant. Use a seller that tests both triodes and confirms the exact tube shown is the one shipped.
- NOS RCA Command Series marking
- 5751 dual triode
- listed at $75 by VacuumTubes.net
- Clearly differentiated RCA vintage variant
- Suitable for a collector-minded purchase when compatibility is already confirmed
- The designation does not override an amplifier maker’s socket guidance
Sylvania 5751 Gold Brand NOS
A NOS Sylvania Gold Brand 5751, sold as a separately identified vintage version rather than a current Sylvania product. Inspect photos, test figures and seller grading before paying the Gold Brand premium.
- NOS Sylvania Gold Brand marking
- 5751 twin triode
- listed at $40 by VacuumTubes.net
- Specific branded NOS construction is easy to distinguish in a specialist listing
- Observed price remains below many rarer NOS choices
- No two vintage listings guarantee identical age or test readings
CBS/Hytron 5751 Triple-Mica NOS
A NOS CBS/Hytron triple-mica 5751 for a compatible low-level preamp position. Triple-mica describes internal support construction; it does not substitute for testing the individual tube for noise and microphonics.
- NOS CBS/Hytron 5751
- triple-mica construction
- listed at $30 by VacuumTubes.net
- Distinct maker and construction from the GE, RCA and Sylvania choices
- One of the lower-priced NOS paths in this list
- Old-stock supply is intermittent
Siemens 5751 NOS
A vintage Siemens-branded 5751 listed as European construction. Buy only a seller-tested example and retain the invoice, because vintage branding and internal construction can differ across production runs.
- NOS Siemens 5751
- European construction listing
- listed at $50 by VacuumTubes.net
- A separate European-made vintage option
- Listing identifies manufacturer rather than using an unspecified NOS label
- Scarcer stock can make matching pairs difficult to source
JAN Philips/Sylvania 5751 NOS
A tested JAN Philips/Sylvania 5751 from later Philips-era Sylvania production. KCA notes that Philips acquired Sylvania tube production, so do not count Philips- and Sylvania-marked examples of this construction as separate product families.
- NOS JAN Philips or Sylvania marking
- same production lineage described by KCA NOS Tubes
- KCA listed price $75; balanced triodes $80
- Seller explains the Philips/Sylvania relationship clearly
- Balanced-triode selection is offered by the specialist retailer
- This is NOS inventory, not current Philips or Sylvania manufacture
Buying tips
- Check the amp maker’s documentation before substituting a 5751 for a 12AX7; gain, operating point and function of each socket matter.
- For NOS tubes, buy tested inventory and compare triode balance, noise/microphonics screening and return terms rather than relying on a logo or plate color.
- Do not open an amplifier chassis merely to swap tubes. Tube amps can retain lethal high voltage after being unplugged; use a qualified technician for internal service or uncertainty about compatibility.
As an Amazon Associate and eBay Partner, toptenpick.com earns from qualifying purchases. Prices and availability are subject to change.