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NOS 5751 Preamp Vacuum Tube

1 Review
Out of Stock
SKU: NOS-5751
USD $‎39.95
The 5751 preamp tube is great for taming high gain guitar amps while vastly improving the clarity, smoothness, and vintage tone! They still have plenty of gain but if you have a high-gain preamp that does not have that classic crunch characteristic, the 5751 vacuum tube will do wonders.

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Special Note: The 5751 is not a true 12AX7, but is often used in place of a 12AX7. They generally have 70% of the gain of a 12AX7. If you have gain to spare using a 5751 tube will greatly improve your overall tone without making your preamp excessively clean. You can learn more about this on our tone tweak info page.

Additional Information and Downloads

12AX7 Tube Review

Tube Matching Information:
Matched Sections Service

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

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Good to shear off some gain and some other uses.


The 5751 is a tube I always keep on hand. Some modern amp makers have been known to swap ECC81/12AT7s in the phase inverter stages for 12AX7s as a "design change". If you have an amp that has 12AT7 marked by a socket and a 12AX7 in the socket & a 12AT7 won't work in that position this is a great option. Some Dr Z amps were like this. As a disclaimer I must say I have no idea if they came from Dr Z this way or not for sure, but this tube was an easy fix. Compared to an other Dr Z of the same model the sound was nearly identical, and the amp had been restored to what the customer wanted. The 12AT7 would not work due to plate resistance, but a 5751 has identical plate resistance to a 12AX7/7025.