MH: What's a common misconception guitar players make regarding their selection of tubes?
NSC: A common misconception would be the often-debated subject of "new old stock" vs. "new cheap copies". SOVTEK and Electro-Harmonix tubes are the real thing. Some of our tubes clearly exceed the performance of tubes made by any factory back in "the good old days". First of all, if it wasn't for the guitar amp market, very likely there would be no commercial tubes
manufactured today. For every tube used today in a nonmusical instrument type product (including HiFi), there are thousands more meant for nothing but that. And while this business certainly couldn't be compared to the chip industry, or any other basic element of the consumer electronics business as a whole, it's still a market of some importance, at least to the rock & roll
hardware industry. Secondly, there is a sense of nostalgia that blurs the memory for some, and completely blinds those who aren't even old enough to remember the "golden age of tubes". Manufacturers like Telefunken, Mullard, Amperex, RCA, GE, Sylvania, (sorry if we've left anybody out here...), faced the same difficulties making their products back then that we at SOVTEK/ELECTRO-HARMONIX do today. Difficulties such as finding reliable vendors with consistent materials for making tubes, balancing the cost of development and manufacture against the price folks are willing to pay and maintaining a work force with a culture of production committed to making a good product. We use the best we can get. Our Russian factory, and our 20 years of experience doing business there have made it possible to continue, and in some cases improve on designs that had not evolved in 40 years. For example, the original 6V6 was designed for car radios and military mobile communications. Its maximum voltage ratings and dissipation were limited by the compact design of the package. Rugged from the standpoint of vibration, but 250 maximum plate volts, 14 watts of dissipation, and that's all she wrote. By the time the first guitar amps using 6V6's appeared, the advantages were considerable for manufacturers. The tube was cheap, small and relatively insensitive to the banging around musical instrument amps are generally subjected to. No one cared about service life, so they cranked up the supply voltage and ran them in class AB to squeeze out the watts. One large manufacturer used a 415 volt supply in their popular 6V6 powered guitar amp. This wasn't unusual at all. Now all these years later there aren't too many NOS 6V6's left because folks have burned them all up! The 6V6-EH, made at the SOVTEK/ELECTRO-HARMONIX factory, is an evolved design with changes to the geometry and materials to improve the performance and service life at the high voltages typical in guitar amps. There's no NOS 6V6 ever made like this. It has great tone too!

MH: What's the most common question asked about tubes?
NSC: Probably "why are tubes still around?" Yeah, it's a good question. Good tubes in a good tube amp sound better than the alternatives, any of the alternatives. It's really encouraging, in this day and age of instantly obsolete technological hoodoo, a large number of the best musicians still prefer the sound of tubes. Taste matters. Good sound is important.

MH: What's the most important characteristic about choosing the right tube?
NSC: This will vary with the individual, but you can narrow it down to a few basic concepts... Sound, reliability, consistency and flexibility. One of the unavoidable problems you face is that music isn't a collection of signals or functions that can simply be engineered, it's a culture, a form
of human expression. All the messy human stuff that goes into anything like that also goes into what makes one tool better suited for music over another. We at SOVTEK/ELECTRO-HARMONIX believe that a great tube will be the one that gets you connected to the flow of the music and not worrying about the hardware.

MH: Obviously, New Sensor goes to great lengths to replicate the sound of vintage tubes. How do you accomplish this?
NSC: Well, it all depends which tube you're talking about... The 12AX7-EH, for example, is a small plate, spiral filament construction quite unlike any "classic" tube made by RCA or Telefunken, but has much lower hum and microphonics than the old stuff, while matching the high gain. The transfer characteristic is somewhat more curved than the "original", producing a different harmonic distortion spectrum. The 12AX7-LPS, on the other hand, is a true classic "long plate" construction (this concept only exists because many companies switched to the "small plate" style because of the guitar amp's special requirements). A spiral filament is added for improved hum immunity with AC heaters. The electrical properties have been matched to the "old-school" 12AX7 specification as much as we can make it. All of this means a long straight transfer characteristic with low amounts of odd order harmonics. The 12AX7-EH has a little "bump" in the third harmonic near clipping, which makes it appealing to high gain overdrive freaks. The 12AX7-LPS is for "classic" sound in guitar amps or high performance tube HiFi. So, the answer is that we try to make tubes that fit our markets.

MH: In the day and age of die hard tube amp lovers, what's your opinion on the modeling technology used to recreate the sound of real tubes?
NSC: Modeling seems to offer convenience over sound at this point. Today they don't get that close to the qualities that make the best tube amps desirable. For the musician that needs 14 different amps and effects in some particular circumstance, but for one reason or another (whew!) cannot drag the equipment around, nothing can compete with a modeling amp! Also, it
seems to me that most of them just use a little low pass filtering and some wiggly math in their approximations of tubes and this is a crass oversimplification of the subtlety and harmonic richness of the real thing.

MH: In your opinion, what model of power amp and preamp tubes are your preference?
NSC: We are especially proud of our 6L6-EH. Any style of guitar playing will benefit from the power and tone of these tubes. Most manufacturers already buy them from us for use in their amps, but if you haven't tried them, you owe yourself a listen. For preamp tubes, the 12AX7-EH is the hot tube right now. Again, most of the large manufacturers are already using them, but if you're a Marshall user, switching to this tube will increase your drive, lower the microphonics and give you an edge you will love.

MH: Any special equipment or technology that New Sensor utilizes to manufacture some of the greatest tubes in the world?
NSC: We've made a concerted effort in the last two years to improve both analysis and testing of tubes with the goal of identifying areas of improvement and implementing changes to the tooling and production methods. Our engineers in Russia and in New York have worked together to do this. We have also built a sophisticated computerized automatic tube tester for grading and matching tubes. We maintain a database of the testing results in order to better understand how the yield is holding up, in terms of consistency and also to keep an eye on the distribution of characteristics. It's a good mix of the old and the new. Imagine testing vacuum tubes in a computerized tester!

MH: How important is truly matching tubes when they are replaced?
NSC: This is obviously still a controversial subject for some, but we would hope that some common sense is used when replacing tubes. There is no question that a good set of matched tubes helps the low end extension of an amp and reduces hum, distortion and increases the output power slightly. There are many factors that affect the actual current draw in the output stage beyond the matching of the tubes in a tester. The best matched pair of
power tubes in the world will still draw different standing current in amps using wide tolerance parts in the biasing circuits, in amps that have a very high screen supply voltage (most amp manufacturers exceed the maximum rating), or with low quality asymmetrically wound output transformers (often an important feature of many great guitar amps). As long as the tubes are within 4 or 5 mA and 500 µMHO transconductance of each other in YOUR amp, they're matched well enough to get the benefits. None of the companies that made amps back in the day ever shipped anything with matched tubes, and no one ever cared. The old classic stuff is pretty insensitive to tube selection. However, some of the really high gain, high power amps made today would probably self-destruct if the tubes were really mismatched. We match within
+/- half mA and within +/-100 µMHO in our tester. That's two point matching, and I don't think there are many, if any, tube manufacturers who do this thoroughly? This is a precision jig with regulated supplies and 1% parts. Very few real world amps are made this way and frankly they just don¹t have to be made that way either.

MH: What are the signs of poor performing tubes?
NSC: There are several different ways that tubes fail, but generally speaking one should pay attention to the following: 1) How is the lower register? Does the amp have punch down low? This is a sign of the peak current dumping capacity and a great thing in any amp. If the amp sounds thin or shrill, with no warmth or "chunk" to the sound, the tubes just aren't swinging enough current and it may be that the tubes suck. 2) When the amp clips, does it do it smoothly? Are the harmonics produced nice and "chimey"? Or, do they sound like the amp is going through a stomp box with a dying battery? Maybe you like that sound? Otherwise, the tubes probably suck. 3) Are the tubes ringing by themselves, or making other strange noises that don't have anything to do with whatever it is you are doing to your guitar or bass? If yes, chances are that the tubes suck. 4) Does the amp make sudden changes in volume or tonal content that "fix" themselves when you stop playing? If this is not due to a malfunction with the amp, there is almost no doubt at all that the tubes suck. 5) Do the tubes sound good? This is really a messy question because it involves taste and personal judgment. But, it is the most important question to answer. If the tubes sound good in your amp, they are very likely perfect.

MH: How often do you advise changing tubes, and what maintenance can be done to make tubes last longer?
NSC: We are tube manufacturers! You should change them every year or even sooner! The more the better! No, really, modern amps will need the tubes replaced much more often than your old classic. Probably within 1 or 2 years. But this depends on how much the equipment is used and in what way. Keeping the amps properly maintained and biased will absolutely improve service life. A good relationship with a responsible tech can help sort this out.

MH: What's the best piece of advice you can pass along to die hard tube junkies?
NSC: Vacuum tubes are here to stay. As long as you nuts are making amps and music with tubes, we plan to be the ones making the best. As Mike Matthews, New Sensor's owner and big fishing guru says, "ROCK & ROLL!"