I just checked out Sweetwater's new demo of that new pedal that uses one of Korg's NuTube's. It was a very informative demo if you haven't checked it out yet. After digesting that I downloaded the NuTube datasheet from the Korg website so I could take a look at its electrical qualities. I'll break my thoughts into two categories... sound of that pedal from the video and then the side of NuTube technology.
To be as nice as possible, it sounded okay. My very first thought was that sounds like butt, but then he bypassed the pedal and played clean and it still sounded like butt. Okay, upon more listening I thought to myself, "where's the headroom?" That marvelous headroom that you can only get from real vacuum tubes running at very high voltage... not 9, 12, or even 18. So basically, they're selling a starved plate pedal for $250. But is it a real vacuum tube?
I took a very thorough look over the data sheet with my vacuum tube scientist hat on. It appears as though the NuTube is a tube with a directly heated cathode. That means no cathode biasing, grid only. That also means no cathode follower circuits, which are great for driving low impedance loads. The data sheet specifies the plate resistance to be 330k Ohms, which is significantly higher than any vacuum tube I can think of. That means any circuit utilizing these "tubes" will have a much higher output impedance than a typical vacuum tube (which is high compared to a transistor). That's probably why that new pedal doesn't have a bass knob. A treble roll off pot (like on a guitar) doesn't need a driving force to make it work. Having the ability to boost and cut, as in a bass & treble configuration, generally requires a low impedance stage to drive the EQ circuit properly, thus ruling out the use of a NuTube. Another point to make is it will be next to impossible to design a circuit with these in which the NuTube drives a line output transformer. I'm thinking anything studio related - mic preamp, compressor, microphone, etc. But even if it were possible to incorporate transformers, why would you? The NuTube's greatest flaw when comparing to a traditional vacuum tube is its lack of headroom. It surely has more headroom than a transistor, but with a maximum plate voltage rating of 80v, its no where near tube town. Headroom comes from the voltage. More voltage = more headroom. If you ever compared a starved plate pedal next to a high voltage pedal, you'll know what I'm talking about. Big difference in feel and tone. When it comes to a studio application where high fidelity sound is paramount, tons of headroom is most desirable. One of my favorite things about tubes is the insane amount of headroom you can get out of them. Its the reason why tube gear tends to sound "big." Lastly, the NuTube is not as small as Korg likes to tout. Dimensionally speaking, it is thinner than a 12AX7, but there were many vacuum tubes developed that are far smaller than the NuTube. Take the NuVistor for example. Where do you think Korg got the name NuTube from? That's right, the NuVistor was invented in the 1950's to be the vacuum tube's answer to the coming transistor. Its literally smaller than the size of a thimble. Freaking tiny. Korg states their NuTube to last 30,000hrs, which is longer than a miniature vacuum tube's (ie. 12AX7) rated 10,000hrs. But, and I mean a very big BUT, the NuVistor had a rated 100,000hrs!!!
In summary, the NuTube is an interesting development and well suited for starved plate distortion circuits. It does exhibit excellent power efficiency (2% of a 12AX7), even better than a NuVistor, (~40% of a 12AX7... bearing in mind that was way back in the 1950's!!!). But where the NuTube fails is its diversity due to high plate resistance, directly heated cathode, and low headroom. With a current price of $47.79 USD per NuTube, I can guarantee you I won't be designing these into any new products. You can get a decent current production 12AX7 for under $15 or a great NOS tube for under $45!
12AX7 Amplification Factor = 100
6CW4 NuVistor Amplification Factor = 65
12AU7 Amplification Factor = 20
NuTube Amplificaiton Factor = a measly 14.5
Amazing developments happened for me in the technical world of electronics over the course of 2017. Those developments helped pave the way for a future of less expensive, more reliable, and sexier sounding products. To start off the new year right, LBA will be in attendance at Winter NAMM in Anaheim, CA. My first goal for the year is to unveil a new and amazing game changer of a pedal at the convention. I'm hustling to make it happen, but limited funds are making that goal very difficult to achieve. Fingers crossed on that one! Next up I hope to release my Trinity channel strip this year. The goal is to do it by September, which will make it 4 years in development!!!! Those products will need me to get the word out on them, so that's probably enough for one man to tackle across the span of 2018. Please share the word of Lightning Boy with your pals. Thanks for visiting :)
I decided to take her apart last week to make some modifications. The previous amplifier topology was SRPP, which worked well, but after hearing a number of my mixes through this board I felt it was too colorful. Yes, there's such a thing as too much color! Plus, the tone of SRPP amplifiers is slightly gritty IMO. I wanted a smoother cleaner tone, like what I'm getting out of my Trinity channel strips. That required a new power supply for the board, more tubes, and a whole lot of work. But, now that its done and working I can say it sounds exactly as I had hoped... maybe better! I also needed to add a couple extra controls that I felt were necessary after working with this board for about a year. I added a VU meter kill switch (sometimes I like slamming the output of the board, which pegs the VU needles). I also added VU meter L/R calibration pots. I felt like the meters were too arbitrary before, so now I can dial them in exactly. Lastly, I changed the role of the trim pots from being amplifier input volume controls to output attenuators (post output transformers). This just makes a whole lot more sense to me, because now I can attenuate any noise from the amplifier stage when I attenuate the volume. Speaking of noise, that was a subtle trade-off switching from the SRPP output stage to what is now single-ended. Simplicity and noise rejection are the hallmarks of the SRPP topology. Super sexy tone, low noise (practically as good as SRPP), wider frequency response, greater degree of amplification, and much lower THD are the benefits of the Trinity design, which is a single-ended, Class A, ultra-linear pentode amplifier. I you want to hear the board before all this, you can check out my past work at www.lbastudios.com. It will be a little bit before I can get some new mixes done through the updated board. I'm really looking forward to it though!
LBA will be at the NAMM convention in January in Anaheim, CA. LBA pedals will be featured on a pedalboard, hooked up and ready to demo at a shared booth, thanks to the Deli Magazine/StompBox Exhibit. The Stompbox Exhibit will be supplying a headphone/amp sim rig for testing. Not an ideal demo scenario, but better than none! Stomp on by to check out the Op-2 Comp, the Thunder Knob, and hopefully something new and very special! Hint hint. ;-)
Seems like most people simply don't understand how and when electricity can actually kill you or not. I put warnings on my pedals to let people know there is high voltage inside, but rest assured, it can't actually kill you. High amperage alternating current is what kills. That simply does not exist in my pedals or anything I build. My tube gear runs on low current DC. Sure the voltage is high, but the voltage is not what kills. For instance, the Thunder Knob runs at about 200 volts DC internally, but there's only 100mA of that hanging out. I've been shocked by it and I'm still alive and well. In fact, I had the misfortune of getting shocked by 400 volts at 250 mA. That was a bad day. Once again, still alive. There's a lot of misconceptions about high voltage tube gear on the internet. I've probably been shocked by high voltage DC a couple dozen times in my life and even AC from the wall outlet a few times. Still alive. I have to put the warnings on things because I don't want anyone to go poking around with the power on. A shock is not pleasant. Very high voltage, high amperage DC could potentially cause burns or worse, but that's just not possible with the stuff I build. The warnings you see at power substations and on high voltage power lines is very real. That's high voltage, high current AC... a very different beast altogether. Remember those stories of Edison trying to discredit Tesla's AC electricity by publicly electrocuting animals? Edison was touting his DC as a safe form of electricity, which it is for the most part.
I've been taking my time on the design on Trinity. I want to make sure its absolutely perfect through and through. Its really something I see as my greatest endeavor. I certainly have vastly more money and time tied up into the R&D of this than anything I've done before. It has to be as perfect as I can make something or it can't be released. The image above is the latest prototype... #008. Please bear in mind there are many more than 8 revisions. This is just the 8th completed unit. Upon building this I decided I want to make some changes to the front and rear panel layouts with the next build. In this particular build I massively fine tuned the electronics. In previous builds there was some (inaudible) subharmonic noise when the EQ was engaged. I redesigned the EQ amplifier stage and added an extra transformer to the EQ stage (interstage transformer). This eliminated all the noise issues. This is the first Trinity with a printed circuit board incorporated. Hold on! The PCB is 100% related to the onboard power supply section. All of the audio is still point to point wired! With the next Trinity, the power supply will have a discrete time delay circuit added to power on the high voltage B+ after the tube filaments heat up. Its been breadboarded and designed in the computer already. I'm feeling very confident the next build will be the first production model. I'm also very excited for when that moment arrives! You can check the fine details of this product on the Trinity product page or you can hear its sounds in action by checking out my recent productions for hire over at http://www.lbastudios.com
There are as of right now 7 videos on youtube demoing the Thunder Knob pedal. I compiled them in one playlist that will surely grow over time. The permanent link to said playlist is here for your intrigue:
I'm recovering from an extensive sinus surgery and plan to get back to work on Monday. I'm super anxious to get back to work. So much so that I have been working from home designing a PCB for the Trinity channel strip. I'm building another one for LBA Studios and at the same time I'm perfecting the product as I inch closer to an official release. Trinity is by far the longest, most expensive, and most extensive product R&D in the history of LBA. Its been years in the making. The design itself was finalized a few months back. Now I'm at the stage of fine tuning the looks and streamlining the build process to get the price down as far as possible without compromising sound or quality.
Truth be told, Trinity has been on the shelf for most of the past year as I worked to develop an LBA-worthy overdrive pedal. Now that the Thunder Knob is out I feel like its time to get back to my hearts truest desire. Its truly a massive undertaking both financially and mentally to get Trinity from concept to product. But, I'm back on track and determined! I believe it will be my greatest achievement for a long time to come.
The PCB I designed for Trinity during my recovery from surgery is for the onboard power supply, which is rather elaborate. This new onboard supply was developed a few months back. It helps reduce noise, cost, and build time. It takes a 12VDC input and spits out 250v @ 200mA, 250v @ 100mA, 48v @ 250mA, and 6v @ 300mA... all of which are highly regulated for superior low noise operation. I'm planning to build an external power supply unit that will distribute 12VDC to 2 Trinity channels. I'm also thinking about building a larger power supply unit for powering 8 channels.
I'm not sure when Trinity will officially be ready, but I'm not concerned with that either. Its done when its perfect. Its very close to done. I think the next build after this one will be "the one."
About the Author
Mike Congilosi II, Owner/Designer/Electronics Engineer at Lightning Boy Audio and Owner/Audio Engineer/Music Producer at LBA Studios.