Mullard 12AX7 Preamp Vacuum Tube, Single

I'm running 2 Heathkit model A-9B mono blocks as a stereo set. After careful research, I choose these Mullard preamp to replace the worn vintage RCA 12ax7 and 12AU7 tubes I had in these amplifiers. At the same time, I replaced Sovtek 6L6GC output tubes with the current production Tung-Sol 7581A tubes. I'm blown away. Despite these amplifiers being rated at 20 watts RMS, they are driving a pair of Boston A-360 speakers to fill my room with delightfully clear and brilliant sounding music. The bass response is powerful and clear, detailing all of the aspects of the notes whether from Steely Dan's punchy clean style, Chicago's flowing melodic style, or Yes with that distinct Rickenbacher/rotosound combination. For mids and highs, the horn section from Chicago is absolutely stunning through these tubes and the great guitarists playing psychedelic riffs with wa-wa pedals and electrifying leads have a clear and very sweet presence in the sound stage. The quality is both pleasing and exciting to listen to without a shred of harshness and without a single piercing note (you know, that occasional high note that feels like an ice pick to your set drum.) This pair of Heathkit amplifiers just went from sounding pretty darn good to sounding awesome in ways that very very few amplifiers could never touch. If you've ever heard a Marantz or McIntosh with tubes, we are in that arena of fidelity. I choose these Tung Sol 7581A power tubes for this application because of reviewers who criticized them for being too clean in a guitar amplifier. Given this excellent performance in my High Fidelity system, I would agree; these tubes contribute no discernable distortion which would make them undesirable in a most guitar amplifiers, but it makes them AWESOME in a home stereo! My choice of the Mullards for the 12AX7 and the 12AU7 tubes was based on similar research where the Mullards were being criticized as too clean for guitar amp service but praising the small Tung-Sol tubes for a sweet guitar amp tone. These Heathkit A-9B amplifiers were speced out for less than 0.1%total harmonic distortion at the rated 20 watt RMS output with less than 1% Intermodulation distortion and a flat response curve from 6 Hz to 50 kHz and a -70dB signal to noise ratio. With these tubes, I have no doubt these amplifiers are acting as good as or better that their impressive specs. 20 watts rms never sounded so powerful or moving! If you are considering a high fidelity retube, I very highly recommend this combination.

I put these into my new Pro-Ject Box S to compare to the ones it came with. The other pair I tried after these were matched Gold Lions. None of them are NOS unicorns; none sound poor either. These, however, are certainly the clear winners compared to the other two. Again, I'm aware that we're not comparing vintage NOS tubes made at historic plants of decades past. When you see glowing reviews about certain consistent high performers, (regardless of the make/manufacturer) a few characteristics seem to come up over and over. These tubes deliver on a lot of those benefits in my estimation. If you're someone like me, the curiosity spikes too high to resist "rolling" with a few different brands to get a better idea what's possible or what you might be missing. These were a very good buy to put it mildly. I will try to refrain from using the etherial jargon that semi-newb audiophiles best avoid. To quickly rattle off my own impressions with terms that describe the W O N D E R F U L difference this made: balanced, revealing, rich, clarifying, live-performance buzzy. Vinyl has a "warmth" of its own. But this brings another kind of warmth and, along with it, big big big detail and fuller mids without any buffering or softening that a 'warmth' might imply. I cannot get over how much bigger the soundstage is. The room feels bigger, the music is more natural (and musical), and the separation is better than you might even suspect your vinyl or hi-res music had the potential for. I'll update this if, for some reason, the Pro-Ject tubes that came with the amp are anything to update about.

Have it in V1 position, and paired with a Mesa 12AX7 at V2 in Bugera G20. So I originally had this one in the V2 position and the mesa in the V1. The sound was good and I would have probably kept it that way, but on a whim, I decided to swap the tubes around. Holy crap! I play all sorts of metal to include the newer stuff. I have also recently switched to seven string guitars. This is the gain structure that is meant for all things metal. It is so interesting to me how the sound of a tube amp can be effected by different tube brands. THIS combo in THIS amp though, wow. Guitarists know about this: it is just wonderful when you find a setup that works, or especially a setup that finally provides that "ideal" sound you have been looking for - it is sooooo satisfying. It is my understanding that this mullard tube isn't exactly a high gain tube. But I will say that, in the Bugera G20, this Mullard plays very nicely with the Mesa. You get all the compression and gain, but it is smoothed out and so very usable. So I guess overall I am saying that this is a great tube, and definitely a great tube for the Bugera G20 when used in the V1 position.

Very good tube. I got it to try in a champ build my son and I are building. I have tried it in a champ clone and it has pretty good break up and starts breaking up around 3 and has pretty good break up at full volume. Not sure it's worth all the hype and the extra cost. So far it's a great tube and I have several old stock tubes like the 1957 rca long black plate 12ax7 and sylvania, raytheon, hytron, G.E. and tung sol 12ax7's. Don't know if I would choose this over any of them. My 2 favorite tubes are the rca long black plate and the sylvania short grey plate 12ax7 so this tube has pretty big shoes to fill. Overall it's a good tube and works well in small (5 watt) and bigger (15+ watts) amps.

Worked perfectly in my amp

Some users out there don't really care for these Russian tubes made by New Signal Corp., but I see no problem with them. Upscale Audio gives these a nod and, at the price, I don't think you could go wrong. If you want a livelier tube, you might try one of the Tung Sol or Gold Lion tubes. In my case, I am using a small EL84 tube amp on my computer desktop system, and it uses a single 12AX7 as a driver. The tubes that shipped with the amp were some off-brand Chinese tubes. I replaced all three tubes with these new-issue Mullards (having purchased a pair of EL84s on "that auction site" for less than any price here), and the soundstage is deeper and the music seems a bit more full-bodied and detailed. Overall, a better sound than the stock tubes.

Rolled my tubes and this ended up in the v1 position in my Marshall with a genalax gold lion in v2 (SURPRISED ME) and jj gold long plates in 3 and 4. Out of all the tube variations I've tried this is the best I've found for my dsl40c. And the quality of mullard is so good I went with them for my el34 power tubes. Clean channel has headroom so lush it seems you could grab a note out of the air. Overdrive channel that will go from zz top to metallica just by rolling the volume on your guitar. Went from a good sounding amp to a great sounding amp.

I recieved a pair of the Mullard preamp tubes and installed them in my Vox AC15CC. The power amp tubes I am currently using are Sovtecs (until the Mullard EL84s arrive). I did not expect much other than mediocre performance; however, when I turned the amp on I was very surprised! Ealier breakup than JJs and a much more jangly British Invasion sound. The bass is very balanced and the articulation between strings when overdriven made me giggle with delight as I played "If You Can't Rock Me" (Stones) and You Shook Me All Night Long" (AC/DC). These tubes gave my AC15CC new life and it was very easy to adjust the tone and gain to find a sweet spot at a lower volume than I was accustomed to. I will stick with New Sensors Mullard Reissues from now on.