One of the stock tubes for PrimaLuna EVO 100, ProLogue Classic, and earlier ProLogue products with a preamplifier stage. Made to a high spec for PrimaLuna by Shuguang in China, this is a quiet, reliable tube that does everything well, and is offered at Platinum grade.

Some customers report that the gold pins are smoother, and with a bigger soundstage than the regular version (above), and offer a more refined sound. Otherwise, they are very similar to the original.Low noise and microphonics, but if you have a really high-gain phonostage, or want a more relaxed top end, the Mullard would be a better choice. Gorgeous mids, great dynamics, and a nice 3D soundstage. 

Fun fact

The filaments are almost completely encased, so these won’t glow as brightly as other 12AX7s.

This 12AX7 is a reissue of the famous Mullard CV4004, hence the double-moniker. It is a short-plate version of New Sensor’s excellent Mullard 12AX7, and is reported to be even quieter, so this is the solution for a touchy preamp or high-gain phonostage. Like the long plate, it has a smooth, warm midrange, and is a little relaxed on top. 

Customer reviews 

This tube is warm, yet crisp and clear, and customers suggest this is a good way to add life to a sterile-sounding system by adding warmth without losing top-end detail. This is a good way for brass instruments to have body and warmth and keep their bite. 

A full, glorious midrange with great texture and liquid detail, extended yet controlled highs, tight bass. Very quiet and low in microphonics. 

Customer reviews 

Users report an open, slightly laidback, tonally balanced presentation, and love how quiet they are. 

Fun fact

Due to the larger plate structure, if you're the kind of person who likes to thwack tubes with their fingernails... these will likely reward you with a loud "PING!" through the speakers. The solution? Don't thwack them with your fingernails! 

When Kevin thinks of this tube, he thinks of turning up the color, in much the same way classic Mullards do... smooth, maintains top end, excellent bass. The midrange especially is fabulous.

Customer reviews

Customers think of this tube as one that "shines in the entire frequency spectrum", with notable sparkle on top, and a real sense of magic or specialness. There are reports of more weight and definition, greater richness, and lots of increases in soundstage depth. 

More lively on top than the earlier production grey plate. Very neutral and clean, with excellent extension on top. This is not a warm sounding tube, so if that's what you're looking for, check out the Mullards.

Customer reviews

The feedback matches Kevin's description, that this tube is rich and uncolored. Naturalness and references to the real sound of instruments are common, with mentions of good dynamics, and greater precision.

The most sought-after 12AX7 we have. Glorious mids, smooth as silk, and on the warm side.

Customer reviews

Known to be the "best of the best", and such a huge improvement over old or stock tubes that even skeptics consider these well worth the price. After words such as "glorious", two instances of "gobsmacked", and many, many "wow"s, it's clear that the world will be a little colder when these tubes are gone. To balance out all the fantastic reviews, one customer found them too syrupy in an already warm system, but loved them in a more neutral setup.