Mullard CV4003 / M8136 / 12AU7
The NOS Mullard CV4003 (M8136) tube is a British military grade ECC82 / 12AU7 tube type. This 12AU7 tube has box plates which seem to improve resistance to microphonics and noise. They were produced in Mullard's Mitcham factory during the early 1980's. Not all are labeled exactly as shown. Some samples in the military packaging do not have the "Mullard" name but rather the military part numbers only. All do have the etched factory code however, proving authenticity.
The Mullard CV4003/M8136 tube has a deep and expansive soundstage, with overall fantastic definition. The lows are defined while the mids and highs are liquid smooth, just leaning to the warm side of neutral.
Other Mullard tubes 12AU7 Tube Types
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Warranty Information and Return PolicyWarranty 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
Best tube for Jazz enthusiasts.....
by Lalit -
Beautiful sounding tube. I end up preferring the Mullard over RCA clear top ( known for top high-end extn.) The Mullard’s were slightly laid back yet detailed with spot on tonality. These lean towards bit warm presentation. If you prefer a slightly laid back and relaxed sound, this is your tube. No listening fatigue here.
I bought 2 of these to put in my rouge audio sphinx v2. made a huge difference from the stock ecc802s JJ tubes, less forward and not as bright. Very big soundstage added a little warmth to the top end while still being quite detailed. Midrange is magic as many others have described on other forums
by Brien -
I purchased these tubes on recommendation from a friend as I was looking to replace the stock tubes in my Xduoo TA-20 headphone amplifier which were a bit noisy and didn't sound all that remarkable to begin with. As soon as I swapped out the stock tubes with these Mullard tubes, everything changed, it was like I was listening to a completely different device. The soundstage opened up massively, the noise floor was drastically lower, not completely gone but I do understand that's difficult to do with tubes, and then the midrange, omg the midrange. It's almost magical now. Precise yet laid back, warm yet not bloated, the bass shows up and it is rather glorious as well, but the midrange of these tubes really steals the show, with the highs being very complementary, not overly aggressive or laid back, very well balanced. Yes these are a bit on the expensive side, but they're very much worth every cent in my opinion, get a pair/set/whatever-your-device-takes and you won't be disappointed.
Best tube I have ever had
by David Rinehart -
Great tube from highs to base I have a Rogue Sphinx 2 and had RCA nos tubes in it and they sounded good but could get I bit bright these tubes made the amp sound much better totally natural sound they are that good
Didn’t last long
Despite the general reviews and consensus, the Mullard 12AU7’s didn’t offer any benefits to my pre-amps stock J&J tubes. One of the two tubes installed was shot after only 160 hours of run time. May have simply been a poor pair of tubes.