Mullard CV2492 Gold Pin
Made in Great Britain in 1974
Long Life Military Quality
(Rated for well over 5,000 Hours)
*Unused – NOS – Very Rare*
Amplitrex Tested
$150/Matched Pair
(Only 2 Pair Available)

Alternative Recommendation for LIO = 1984 6N23P Chrome Pin Reflector


Contact Me If You Might Be Interested

(Please Note: Be careful when purchasing Mullard CV2492 tubes. They’re old (1974 = 42 years old) and specs can and do drift over time even though the tubes are unused! I’ve accumulated 20 pair of these NOS tubes and only 11 pair ended up testing close to factory specs. The other 9 pair tested poorly and I ended up selling them at a serious loss!!! The 9 pair I’m selling here all have been tested using my stellar Amplitrex tube tester. All tubes are new, previously unused, and in original factory military boxes with the Mullard factory paper wrap and bakelite tube pin protectors.

Most tube testers are all over the board in terms of accuracy and the ability to provide a true and consistent test result. You cannot do better than Amplitrex testing and I’m taking a considerable loss selling these tubes at my asking price since I really should factor in the “poor” tubes that I had to purchase and sell at a loss to find these 9 good pairs.

All of these CV2492 tubes have been sorted into matched pairs and every one of the 9 matched pair that I’m selling are superb. I’ve tested each tube for over 5 electrical parameters and have used headphones to listen to each tube for microphonics.  These are some of the best Mullard CV2492 that you will ever find! If they don’t test to my test specs, I’ll be glad to replace them, but I assure you that they will. If you have them re-tested, make sure that an Amplitrex tube tester is used. Few testers provide repeatably accurate results like the Amplitrex does.)

Full Range Speaker Systems

If you have a full range driver style speaker system (i.e. Zu, Omega, Tekton, Fostex, Mark Audio, Tang Band, Lowther, Sonido, Rethm, and a whole bunch more), the Vinnie Rossi LIO (without one of it’s tube stage or AVC/tubstage modules installed) can be too “clean” and “pure” to make these speakers sound really right. The LIO’s distortion will be super low and detail will be uncanny, but generally, your midrange presentation will be lean and not as beautiful as it could be.

This is not a LIO problem, however, and can be remedied by installing a LIO Tubestage!

Rather, it’s a limitation that many of you might have experienced while owning full range speaker designs. If you have the ability to measure your full range speaker frequency range, you’d find all kinds of peaks and dips that cause huge  music playback reproduction problems. These systems don’t have crossover networks to correct numerous deficiencies ALL speakers have, and I haven’t found a full range driver that is perfect on its own without crossovers. How do I know this? I’ve built and purchased speaker systems using most of the above listed drivers over many years and have discovered these problems myself through direct listening and testing. I’ve had huge expectation for full range driver systems and finally, today, I am no longer interested in them because they typically don’t allow me to listen to all genres of music.

So if you already own a LIO system (or are considering one) and have a speaker system that sounds a bit lean in the midrange or strident in the high frequency area (even if a crossover style design), you definitely should purchase Vinnie’s tube stage or AVC/tubestage module! And . . . there is one NOS tube that I’ve found that best help’s to minimize or eliminate full range driver or lean crossover style speaker problems with the LIO tubestage: the NOS Mullard CV2492. Used in the LIO tubestage, these tubes are the ultimate for creating a midrange beauty and satisfying musical presentation!!!

The NOS Mullard CV2492 Is “Scarce” & Difficult to Find In Superb NOS Factory Spec Condition!

Two of our big tube sellers (Upscale Audio and Brent Jesse) no longer have these tubes in stock. You’ll find some poor examples on eBay, and perfect factory spec NOS examples are becoming collectors items and almost unobtainable. Rarely can you find let alone purchase a NOS unused pair that tests at factory specs. I was able to accumulate a stash of these tubes in superb NOS condition, but I had to purchase 20 pair of these tubes (at a little over $230 a pair) to find the 9 pair that I’m selling. 11 pair tested below factory specs and I had to sell them at a considerable loss!

I’m not including the loss I’ve taken in my purchase price for this 9 factory spec pair since my goal right now is to get rid of my entire tube collection and move away from building tube amps. I’ve tested all of these matched unused pairs on my Amplitrex tube tester and each pair that I’m selling is in full factory spec condition. Each tube is in its original factory box and is “cigar” wrapped in the Mullard paper wrap and also has the bakelite tube protector installed on the pin end of each tube.

I’m Now Selling 9 Matched Pairs (at factory specs) NOS Mullard NOS CV2492 From My Private Tube Stash

I paid $115 per tube ($230 per matched pair). I’m selling 9 of these rare pairs to anyone who might be interested. When they are gone, there won’t be any more from me. That’s it! My price is $250 per Amplitrex tested factory spec’d matched pair plus $6.80 USPS Priority Mail shipping cost. This is below my actual cost and lower than market if you could even find these tubes for sale in the same condition that I’m selling. If I wasn’t getting out of the tube and tube amp business, I never would consider selling these rare tubes at this low a price. I’d hold them as a future investment.

$250 Per Amplitrex Tested Matched Pair

In all honesty, I should hang onto them and wait while they go up in value. They will. However, I’m getting out of the tube business and will no longer be building tube amplifiers in the future.


The Vinnie Rossi LIO has turned my audio world upside down and is the only electronic component that I now desire to use or represent. It is so good, that I am more interested in helping Vinnie with the marketing of this wonderful component rather than continuing to build my own amplifier and volume control designs. Also, I’m now using the Harbeth HL5+ speaker system and because of the already beautiful midrange voicing of these speakers, I find the 1984 6N23P Chrome Pin Reflector tubes ideal with the Harbeth speakers.

This new approach (for me) solves all of the audio problems that I’ve been working on for several decades. It simplifies my approach to audio (eliminates expensive cables, power conditioners and multiple boxes) and it provides a sound quality better than what I’ve been able to create on my own while allowing me to listen to all genres of music whether recordings are poorly made or incredibly well done. I couldn’t ask for more. In today’s economy, you might think that the LIO is expensive but in all honesty, for what it provides, it’s an incredible bargain! With Vinnie’s tube stage (and AVC volume control) it competes with the best at a considerably lower price!

The Best LIO Tubes?

There are only two tubes that I’ve found useful in my own LIO and with various speaker system designs. I’ve tried and owned most 6922 family tubes ( 6922/E88CC, 6DJ8/ECC88, 7308/E188CC, 7DJ8/PCC88, 6N23, 6H23, 6N11, and 6GM8) and most brands including the rare and expensive Siemens CCa tubes.

The best tubes for “tuning” the LIO are the Mullard NOS CV2492 gold pin tubes, and the Reflector factory 1984 6N23P chrome pinned tubes.

The Mullard NOS CV2492 with gold pins is the ultimate tube set for speakers other than Harbeth.

If you own a pair of Harbeth speakers, I highly recommend using the difficult to find 6N23P 1984 Reflector family tubes with chrome pins. And yes, these definitely need to be the 1984 vintage and not any other date for my recommendation to hold true!

Both of these rare tubes (Mullard and Reflector) work well with Harbeth. For leaner brighter speakers, however, the Mullard CV2492 is the best.  The Mullards add the missing midrange depth (they have that liquid smooth midrange), body, and beauty and are ideal for most any speaker system where the mid range frequencies could use some improvement.

When reading about tubes in online reviews, you really need to account for the electronics used and the speaker systems paired with those electronics. I don’t put much weight into what various users have shared since I don’t own the equipment that they are using. Tubes should be used to “tune” specific amplifiers to match specific speakers and correct various inherent deficiencies.

What I’m sharing about the Mullard CV2492 is specific to the Vinnie Rossi LIO tube stage and two types of audio speakers – Harbeth and non-Harbeth.

The LIO has one of the most linear frequency presentations that I’ve ever had the pleasure of listening to. There is no hole in the frequency spectrum nor is there any false emphasis top, middle, or bottom. As a result, the superb detail that is present in the LIO comes through without much change to what is on the original recording. Nothing is held back nor is anything added that wasn’t there. Adding the LIO tube stage adds a little more warmth and potential beauty even though it is 2nd order harmonic distortion that tubes create and distortion is distortion. However, that little bit of human ear preferred distortion is nice to have but no, it isn’t necessary if you own a Harbeth speaker system. Other brands of speakers – yes, the tube stage and a Mullard CV2492 can make a really pleasant and positive difference. For me, even with my HL5+ Harbeth speakers, I still prefer having the tubestage in my signal path (and of course I’m using the AVC/tubestage module).