Keep Those Filaments Lit, Design Your Own Vacuum Tube Audio Equipment

It was a cold January Saturday night in Chicago and we had big plans. Buddy Guy’s Legends bar was packed. We setup directly under one of the PA speakers less than 15′ from the stage. Time to celebrate. Skip the glass, one pitcher each and keep them coming. We’re about to make bootleg recording history. Conversation evolved into bloviation on what our cover art would look like, certainly it would be a photo of our battery powered tube mic pre-amp recently created in my basement lab. We had four hours to kill before Buddy’s appearance. Our rate of Goose Island and Guinness consumption would put us at three-sheets to the wind by 11. Must focus. It’s time, Buddy was on. Much fumbling about and forgetting how to turn on the Japanese-made 24 bit digital recorder with its nested LCD menus, cryptic buttons, and late 90’s firmware. Make it work. We did, just in time for the bouncers to notice the boom mike and battery packs. Wait, wait… maybe we should talk about why tube amps are worth this kind of trouble first.

Yes, vacuum tubes do sound better than transistors (before you hate in the comments check out this scholarly article on the topic). The difficulty is cost; tube gear is very expensive because it uses lots of copper, iron, often point-to-point wired by hand, and requires a heavy metal chassis to support all of these parts. But with this high cost comes good economic justification for building your own gear.

This is one of the last frontiers of do-it-yourself that is actually worth doing.

Vacuum tubes work by thermionic emission, meaning that electrons are emitted by something really hot under vacuum. In this case a lightbulb filament or a lightbulb filament that heats up a cathode metal plate encircling the filament. These electrons are accelerated from the cathode to the plate, thereby flowing current from the cathode to the plate. This current is controlled by a control grid, literally a small wire mesh between the cathode and the plate that looks like window screen. For practical purposes the grid is similar to the gate of a field effect transistor although the physics are completely different. There are some enthusiasts who actually make their own tubes from scratch.

It is easy to get sound out of vacuum tube audio circuitry. Tube circuits lend themselves to self biasing and simple first-order approximations. Buy parts today and listen to Jimmy Hendrix by Sunday evening.

How a simple single-stage tube preamplifier works

vacuum tube pre-amp
Preamplifier. An example of a 20 dB audio gain stage.

The audio input is fed directly into the grid of V1, which is also shunted with resistor R1. R1’s job is to both pull the grid of V1 to 0V potential and also provide a termination impedance to the audio input (in most cases 50K or 100K). R2 and R3 set the gain and bias point. A simple approximation for voltage gain is R2/R3 assuming the tube has a ‘high mu.’ mu is a measure of transconductance or the tube’s ability to amplify, in other words current output/voltage input. Current flowing through the tube sinks a current across R3. This voltage across R3 while this circuit is idling (or not amplifying) is equal to the bias voltage. This configuration is known as ‘self biasing.’ Old-salt engineers will tell you that designing with tubes is easier than transistors. They’re right.

The output is AC coupled with C1 to block the plate voltage from feeding into whatever this circuit is wired to. Like a single-stage transistor amplifier the output is inverted, a rising voltage at the grid results in a falling voltage at the plate.

Power it

tube power supply
Schematic of 120 VDC power supply with regulation.

You will need 50-150V of B+ (or plate voltage, because it is connected to the plate of the tube via R2) and about 1 mA to power this preamplifier. You can achieve this with the following circuit that supplies a regulated 120 VDC using zener diodes.

try two preamps with ur favorite power amp
With two pre-amps you can make a stereo preamp or ‘hybrid’ power amplifier.

It is important to note that tubes are high voltage low current and from a conventional/modern circuit design perspective the resistors seem very high, caps low, and current regulation approaches amateur at best. This power supply works because we only need 1 mA.

Make two

Connect the inputs to your audio source and the outputs to your favorite solid state amplifier. We now have a ‘hybrid amplifier,’ containing a tube front-end and a solid-state back end. Professional versions of this amplifier are for sale by a large consumer electronics manufacturer.

Take it on the road, a true story from my college experience

Battery operated portable tube preamp.
Battery operated portable tube preamp.

So back to the story I started before. My bootleg conspirators and I were well lubricated and about to get the best recording of a live concert to date when we were stopped by the bouncers.  After a short interrogation we were booted out, back onto the cold streets but with a feeling of satisfaction that, although we did not record the show, we had the best audio gear in town:

Schematic of battery operated tube preamp.
Schematic of battery operated tube preamp.

In this design, two pre-amplifiers described above are used with a battery powered high voltage supply. The high voltage supply works by creating a square wave with a 555 timer. This square wave is above audible frequency, around 40 Khz. The square wave is fed into a small audio power op-amp. The output of this op-amp is back-fed into the secondary of an audio output transformer, generating high voltage AC 170V at 40 Khz. This signal is rectified, filtered, and regulated in a conventional sense. The entire system runs on 8 AA batteries and should operate for approximately 4 hours continuously. Everything you need to make your own is here in this PDF.

Power Amplifiers

Eventually you may want to create a power amplifier. There are a number of classes and variants of tube audio power amplifiers:

  • Class B are push-pull amplifiers, similar to conventional solid state amplifiers, where there is a pushing tube and a pulling tube being driven 180 deg out of phase.
  • The class AB is biased so that the output devices are on all the time, thereby reducing or eliminating cross-over distortion which occurs when one tube hands the load off to the other.
  • Class A amplifiers are basically a high power version of our pre-amp above, where instead of resistor R2 we have an audio output transformer. Lots more power is burned needlessly in Class A amplifiers because they are always on, they either let go of the load or pull it closer to 0 potential. When not doing anything they sit half-mast, burning lots of power. Many prefer class A because there is no cross over distortion and they are very simple to design.
  • More obscure types of amplifiers include transformer-less, where lots of tubes are in parallel in a Class A configuration to directly drive a 4-8 ohm loudspeaker load.

Almost all tube amplifiers require a transformer to match the high impedance of the tubes (3K or so) to the low impedance of modern loudspeakers (4-8 ohms).

Block diagram of a typical tube power amplifier.
Block diagram of a typical tube power amplifier.

Feedback can be applied to all amplifier types, where just like an op-amp circuit some of the output signal is fed back to the input, allowing the amplifier to compensate for non-linearities. Feedback provides a much cleaner signal and improved performance. This is not always desirable depending on your goal. Without feedback expect on the order of 7% total harmonic distortion. With feedback and high gain expect 0.5% total harmonic distortion.

power amp schematic
Schematic of a class AB tube power amplifier with negative feedback.

A typical tube power amplifier is a class AB with feedback. In this, there is a gain stage that also functions as the differential amplifier when feedback loop is closed. This is followed by what is known as a ‘phase splitter,’ which is basically a buffer or small amount of gain using two triodes providing both in-phase and out-of-phase output. The two outputs drive the output power tubes at 0 and 180 deg phase respectively. The output tubes push and pull on the output transformer. Tubes can only pull, so the output transformer is powered from a center tap on its primary winding. Finally, the output is fed both to a loudspeaker and through a feedback network to the first stage.

A working example of this is shown in the schematic with details on its implementation (PDF).

Tube home theater

With these pre-amplifier and power amplifier circuits you can scale your design to a complete home theater system with 5.1 sound. For technical details of its implementation, check out this PDF. You can also check out my project which was featured early last year.

Let them shine

quad power amplifier photo
Four-channel power amplifier located at bottom of home theater system, this is simply four of the class AB power amplifiers described previously.

Just like the reality TV shows where skilled craftsman make motorcycles or hot rods you too can customize the look of your tube amplifier. Place the tubes on the top of the chassis so you can watch them glow. Co-locate the output, power, and chokes on top as well. It’s fun to watch them glow in the dark while playing ‘Dark Side of the Moon.’

Where to find parts

Audio tubes are easy to find and continue to be manufactured in Eastern Europe, Russia, China, and others. Transformers of all types including audio output and power are readily available through Hammond Manufacturing and other sources. A new movement in the tube audio community is to find obscure pairs of output transformers and make single-ended non-feedback amplifiers. Recently, manufacturers have started to remanufacture high voltage axial leaded caps and other old-school parts. You can find this stuff at Antique Electronics Supply, Just radios, and even Mouser and Digi-Key (less expensive for same stuff but requires a lot of filtering and digging through the catalog).

Learn fast

There’s a lot of material on tube design, but these are my personal favorites:

Try vacuum tubes in your next audio project. Keep those filaments lit.

DSC_0318Gregory L. Charvat, Ph.D is author of Small and Short-Range Radar Systems, visiting research scientist at Camera Culture Group Massachusetts Institute of Technology Media Lab, co-founder of Hyperfine Research Inc. and Butterfly Network Inc., editor of the Gregory L. Charvat Series on Practical Approaches to Electrical Engineering, and guest commentator on CNN, CBS, Sky News, and others. He was a technical staff member at MIT Lincoln Laboratory from September 2007 to November 2011, where his work on through-wall radar won best paper at the 2010 MSS Tri-Services Radar Symposium and is an MIT Office of the Provost 2011 research highlight. He has taught short radar courses at MIT, where his Build a Small Radar course was the top-ranked MIT professional education course in 2011 and has become widely adopted by other universities, laboratories, and private organizations. Starting at an early age, Greg developed numerous radar systems, rail SAR imaging sensors, phased array radar systems; holds several patents; and has developed many other sensors and radio and audio equipment. He has authored numerous publications and received a great deal of press for his work. Greg earned a Ph.D in electrical engineering in 2007, MSEE in 2003, and BSEE in 2002 from Michigan State University, and is a senior member of the IEEE, where he served on the steering committee for the 2010, 2013, and 2016 IEEE International Symposium on Phased Array Systems and Technology and chaired the IEEE AP-S Boston Chapter from 2010-2011.

120 thoughts on “Keep Those Filaments Lit, Design Your Own Vacuum Tube Audio Equipment

  1. tube amps don’t have to be expensive. there are transformer companies that make very inexpensive transformers such as Edcor and if you stay away from the boutique tubes you can get workable tubes for a couple of dollars. I built a nice guitar amplifier (5 watts) that is perfect for around the house for under $125 with all new components. the best part: no surface mount devices.

    1. +1 for Edcor, great products, the prices are reasonable, and they’re still made in the USA. Beware, many items are added to the production list when you order, so lead times can be several weeks.

      1. Yes indeed. My own opinion on relative cost notwithstanding, having companies such as Edcor still around and producing great products here in the USA really warms my heart!

    2. R5-D3 in Milwaukee, OR is a great place to get tube, all sorts of tube and good prices. Bad thing, ZERO web presence and check/cash only. But Bob is a walking tube encyclopedia and has quite an inventory.

    3. expensive/inexpensive is the conundrum. To some, laying out $60 for a transformer is chump change, to others it’s a weeks groceries… Honestly, the cost of transformers (yes, even the “cheap” ones) just kills me. I just can’t justify spending that much for what is essentially a chunk of iron and copper. I’m *fully* aware that such a statement is an oversimplification, but there it is. I can’t get past the cost:goods imbalance that exists with transformers (especially considering the relative cost of the other components… resistors, caps, tubes, etc… are all inexpensive [assuming you’re not going with 300B’s and really esoteric caps hand-fashioned by lemurs out of the silk of extinct spiders and strained yak’s milk]). So there you have it. Otherwise, I absolutely adore tube audio… soooo much more listenable (notice that I didn’t say “better”) than most solid state gear.

      1. The actual tube transformers may be that expensive. But you can “hack” regular Transformers, to use them in tube amplifiers. I built a tube amplifier using only regular transformers as found in every spare part box.

        If you folks are interested in that i could translate the build log.

        1. I would be most interested in seeing how you did it and learning method(s) for determining transformer equivalencies among transformer types (ie, a power transformer of this rating is equivalent to an output transformer of this rating, etc…). Absolutely!

      2. interestingly enough, the transformers for the guitar amp I built were $17 for the output transformer and $38 for the power transformer. not really unreasonable when you consider that the power transformer for a similar solid state amplifier I recently built cost $35.

  2. Tube amps do *not* sound better. If you want to add tube mush, make a clean recording and then add it later. That Spectrum article is a piece of crap that should never have been published (Eric Barbour was a crazed tube huckster of the time).

    1. This. It is possible to emulate tube distor… sound using software.
      Tubes doesn’t sound better. It is possible to do high quality amplifiers using tubes and tubes can be fun to work with (or at least different) but for high quality sound even using a modern class D amplifier is a better option.

    2. push a tube amp and a solid state amp into clipping which can accidentally happen when a loud transient comes along and you’ll quickly find that the tube amp recovers much faster than the solid state amp.

        1. you’re right, it’s not supposed to happen, but it does. people like to listen to loud music and along comes a cymbal crash or some other high energy transient. my point is, it does happen and when it does, the tube amp reacts better to it.

          1. Where exactly does this happen, what are the applications that would benefit from tube amplifiers’ saturation recovery? Car stereos? Phones and iPods? The multi-kilowatt systems in clubs and at outdoor venues, maybe?
            Guess that leaves home theater systems, then. Have you ever managed to drive one into clipping?

      1. PS: Don’t get me wrong, building your own tube gear can be fun and educating, like building just about anything else. But don’t pretend that “it sounds better” and you have “scholarly” proof, FFS! It’s like saying you ride your homemade steam-powered car because it provides a “smoother ride”. Which of course would be required in order to listen to your phonograph.

          1. It was an unfortunate choice of adjective, given that Spectrum is more akin to National Geographic than an academic publication. The referenced article should stand on its own merits though, and another commenter already pointed out that assertions do not constitute evidence.
            But my objection didn’t rest on Barbour’s bias. I don’t think hobbyists/makers/hackers do or indeed should build tube audio equipment because “it sounds better” (whatever that means). No more than they build Nixie clocks because they tell the time better.
            Such pedantries are usually reserved for the professional bullshitters.

          2. It really isn’t a scholarly article when compared to actual research with models of the audio voltage/current curves and the distortion actually involved and how and where/when/why it occurs.

            That said, Bob Carver needs a mention in any article about “tubes are better.” He built his amps around a model of the distortion that the tubes produce, and then replicated that in solid state. Showing that it isn’t that “tubes sound better” but that “by the normal setup, humans prefer tube distortion to silicon distortion; so why don’t we model and replicate that”. With modern VHDL production, it should be possible for even amateurs to cook up an ASIC that models the sound from a tube. Now getting it on a board and getting it to match sounds across the whole audio spectrum in the real world instead of the simulator might be more work, but a good challenge.

            I just don’t think the electrons involved in the audio have a magic knowledge of what kind of amplifier they went through. That said, I bought some tubes a while back with the intent of building some stuff for my guitar audio chain. I like the sound and it is easier for me than modeling the spectrum (so far, I’m still picking up VHDL) and I don’t get the chance to play with the high voltages they require as often as I like.

          1. That site may be, but check for similar stuff on amazon or other audio sites. You’ll find ‘tuned wooden knobs’ to get softer sound from the volume dial, because wood > metal or something. And audio rocks ‘resonators’ to help balance the reverb in odd shaped rooms and ‘cryo-gold-plated, sealed, nitrogen filled’ audio cables . . . the list goes on. I’ve even seen a ‘cd repair’ device that supposedly used a CD read laser to go backwards and . . . clean the stray bits that had wandered or something. Maybe the site was a joke that was too subtle for me to get, Poe’s law does apply.

    3. That article is hilarious.
      Some of his facts about transistors:
      >Tendency toward higher distortion than equivelent tubes.
      Duh, everyone knows tubes have flatter frequency response than transistors.

    4. Well, that didn’t take long did it. It’s funny how the anti-tube crowd get their panties in a knot when someone brings up the subject of tube high fidelity audio. I wonder why that is?

      Yes, i suppose tubes don’t sound better if you don’t listen to tube equipment but for those of us who do and have the choice of solid state or tube, tubes sound much, much better. Class D is promising but given the choice, I’ll take a class A/B push-pull over it any day.

    5. Mimimimi. If you don’t like it don’t build/buy it.
      That’s how easy it is. Tubes must have seriously hurt your feelings.
      Are you tube-haters mad because you
      poked them as a kid and got zapped?
      Even if the tube sound is mostly psychological, do you want people
      to buy a crappy chinese AV receiver and make them constantly tell
      themselves “it sounds better” to get a good psychoacoustic impression?

      To the “simulation” theory: That’s like telling people it’s “dumb” to buy and restore a Chevy Bel Air because they could aswell drive a prius with VR glasses and headphones running a Bel Air simulation on.

      Tubes are a great technology. Not too hard to understand, fun to tinker around
      with, easy to repair and thus environmentally friendly, a blast from the past.

    1. What EE’s see as cringeworthy vomit triggers, AE’s hear as smooth, warm bliss. It’s kind of like smelling a can of cat food with your eyes closed vs with your eyes open. Ok, not the best analogy, but whatever…

      1. Maybe canned corned beef or deviled/potted ham. Both good food if you like them (good harmonics for those who like the sound), but if I open a tin of either my cat is convinced they are food for him (totally crap SNR and signal purity).

  3. All of these circuits are pretty standard amplifiers – no hack part.
    But some of you might want to build a wideband VCO using a pentode connected as reflex klystron.
    In case you are interested, google “EF80 klystron”. Ask me for translation.

  4. The author has his amplifier class definitions wrong. In a push-pull amplifier the devices are 180 degrees out of phase. Class A, B, AB, etc describe the portion of the cycle that each device conducts. Class B is a push-pull amplifier where the devices conduct for 180 degrees each and class AB is push-pull where the devices conduct for more than 180 degrees and less than 360 degrees. If the devices conduct for the entire cycle (360 degrees) that would be class A.

    1. In other words… (I think) they act in Class A mode at lower power, until you turn the volume up, then they work in Class B. The idea being Class A sounds better, but wastes vast, horrible amounts of power, where Class B doesn’t theoretically waste any.

      So you get the efficiency of Class B at loud volumes, and the better sound of Class A at quiet volumes.

      Feel free to correct me on that.

      1. Class A is a theoretically linear mode with very little distortion, but smaller efficiency. Class B is a push pull with lots of what’s called “crossover distortion”, which means that there is a flat spot between the top and bottom of the waveform; imagine a 1V amplitude signal, and you feed it through a diode and only a 0.3V signal rectified wave comes out. Now do that for the positive and negative ends of the signal and you’ve got crossover distortion. This is because of the voltage drop from the voltage followers on the top and bottom of the amp. By compensating for this with complementary components, you minimize crossover distortion and create a class AB amplifier.

  5. In the age of Class D amplifiers, Vacuum Tubes are the equivalent of a old steam train compared to a modern electric.
    Sure you can argue there’s more history and experience tubes, but Class D is pedal-to-the-metal precision and efficiency.

        1. We’re still talking about tube amplifiers right? If so, I’ll chip in. I do know lots about steam engines at scale and used to design/build my own but I know nothing about maintaining a full size steam engine that drives a train.

          On the subject of maintaining tube amplifiers, there’s really not a whole lot to it, providing that you have decent tubes and your caps haven’t dried up. I’ve been running a set of push-pull A/B 50W mono blocks for about 7-8 years. They’re home built from 60 year old plans so I messed things up tremendously while figuring out how to set them up but after I got them up and running, they’ve been golden.

          My dad built several amps over the years and has another two big amps (a Marantz design and a McIntosh design) in partial build. He’s 80. He’s been using a 6L6 stereo amp every day for more that 50 years. I think he might have replaced a cap or resistor here or there but more than likely any problems he’s had with that amp was due to poor connections or shorts in the point to point wiring.

          In contrast to that, how long do consumers keep their electronics today?

          1. Yep modern electronics dont last and are outdated fast and 99% of it cant be repaired made in china garbage.
            I dont own a cell phone or crappy lcd tv, sure i have a computer but everything else i own is tube based or early solid state made in the usa or canada, stuff made to last, no chinese trash

    1. False. In the age of Class-D amplifiers only the top experts can design something that sounds reasonable. Working with Class-D amplifiers is hard, very hard and often don’t sound good even with very elaborate control circuits behind them.

      Conversely a tube is the single most linear amplification device requiring minimal feedback to sound great. The circuits are dead easy and hard to stuff up. Transistors aren’t bad either and there are a lot of decent topologies with great performance.

      All of these are several orders of magnitude easier to design and get right than a Class-D amp, and as a result the vast majority of Class-D amps on the market are garbage.

      That said I run a CoolAmp amplifier at home myself so they have their use.

      1. I’m very impressed with TI’s digital chip amps. They’re really efficient and have quality that’s hard to match. The antiquated analog amps (especially the bigger ones) just run too hot to really enjoy here in Austin, TX.

    2. What kind of maintainance equal to a steam train does a tube amp need?
      Replacing a tube now and then? It’s as easy as changing a lightbulb in most cases, and a good tube lasts longer than your chinese A/V receiver itself!
      Capacitors? Good film ones basically last forever and good electrolytics can last 30 years without problems. So what’s your point?

  6. A very long lasting frontier. My Dad designed a hi-fi mono audio amp in the late 40’s or early 50’s. Picked a set of tubes and went to work. I’m looking forward to getting it working again when I find it among the other stuff.

  7. “This is one of the last frontiers of do-it-yourself that is actually worth doing.”
    Did you just tell almost all readers of HaD that everything they build is bullshit? Does sound that way ;)

      1. Definitely cost effective. A small amp case with a speaker is dirt cheap from a yard sale, and my local rummage shop has valves for a few bucks each. Haven’t found any 12AX7s yet, soon as I do I’m putting everything else aside for a new amp stack. But the other valves have some nice sounds to them too, TV audio or even the video amps have some interesting qualities.

  8. Pretty sure you mean to say “DIY that is actually a cost-effective alternative” :D

    Do tubes sound better? Maybe, who knows/cares. But tubes are a neat old technology that aren’t too hard to pick up electronically. They demonstrate some interesting and worthwhile engineering and physics. And if you’re willing to hack, you can play with them cheaply.

    To keep cost down and quality/availability up, I like playing with old TV tubes, especially Compactrons. Dirt cheap, multiple tube elements per glass envelope, and none of the “audiophile” guys want them because they’re for *TVs*. Not that the electrons know…

    1. I’m not sure if you are interested in improving your amps performance but chances are there are only 2 things holding back your amps low end. The first is the transformers, which you can’t really change. The second is that you are using tube rectification, which dictates small PS caps. If you were to improve your PS with SS rectifiers and larger PS caps (low esr) you will see an increase in low end performance.

  9. Nice “scholarly article” written by Simone who makes and studies vacuum tubes for a living. No bias there. Also no evidence or blinded studies, just assertions about how since audiophiles and pros prefer them (with no actual hard data backing up that claim), they’re superior. Scholarly, indeed. Bottom line: tubes distort. They don’t sound better, just different. If you like not hearing what the recording actually sounds like, go for it. They’re definitely more pretty, and would be excellent for showing of to all your friends.

    1. I hate to break it to you, but the only thing that *ever* hears “what the recording actually sounds like” is the microphone element, and the only people that *ever* hear “what the recording actually sounds like” are the folks in the room at the time the recording is being made. Anything after that point is getting the sound colored and recolored ad nauseum. Everyone has different tastes. Just because yours /= theirs, doesn’t mean theirs = suck.

      1. In that they have poorer dynamic range, linearity, color rendition and often resolution than current photographic technology? And that cost per picture is higher by more orders of magnitude than I care to count?
        Judging by your other comments, I’m not sure what you’re trying to argue, but I sincerely hope it’s just a misplaced attempt at trolling.

        1. Kodachrome had better resolution (24Megapixel conservative estimate at full-frame 35mm, and it came in bigger sizes too; going from memory of various web sources) and better color rendition (look at that real chromium yellow! And try getting that cyan color in a normal PC color space). It may have had better dynamic range, the general number for film is considered to be about 14 stops, ±~7 around your target. Sure, there are some full-frame 35mm with that resolution and dynamic range, but they aren’t in the hands of most photographers.

          And that only applies to 35mm black and white (damn Bayer filter). A 6×9 on 120 film, 56mm by 84mm (60 by 90 without the boarders) is almost 5.5 times more surface area, meaning the best film of the day (the 50s and 60s, no less) would have been over 100 MP in each color, and average only a little less. And that’s just medium format, not professional large format 4×6 inch negatives.

          The other way to look at it, instead of making a number up to represent film megapixels would be ‘how much detail can it resolve?’ Using Ken’s numbers on Velvia film, it would be 87MP to resolve the same level of detail in just black and white, without taking the Bayer filter into account.

          I still shoot digital, because it’s faster, easier, and better than I could get from my lenses and developing skills. And develop my own medium format film for fun (instant coffee, cleaning supplies, and a little real photofix) But it’s not as good as some film through really good glass.

        2. In that they’re not just a “patch” overtop of some otherwise “perfect” medium. Instagram filters are for people who fancy themselves photographers but who don’t want to actually have to *do work* to achieve a quality result. Instagram filters are imposed on a really crappy (by all accounts) cell phone camera sensor’s capture. If you want to compare Instagram filters to audio, compare them to the digital “tube modeling plugins” that are available for audio editing programs. But Instagram filters certainly are not a base-level decode like tube amps are. [Torque] gave a crappy analogy and I called him on it (ok, I was a little frustrated, but the “I have a cell phone camera so I’m a pro photographer now” crowd really grinds my gears and Instagram enables such behaviours). Sure, some folks derive joy from instagramming their way to happiness, and that’s their choice… yay for them, may they always be happy, etc…

          Your analogy fails out at Instagram filters being applied to current photographic technology (assuming you’re referring to the leading edge of full frame sensors/camera backs). Anyone shooting with that gear and with the legit chops to support such a habit most certainly won’t be running their work through anything Instagram.

          It’s OK if you prefer solid state audio gear… you’re no less of a person. Likewise, you’re no less of a person if you prefer tube gear. I don’t take offense at people enjoying audio playback (except maybe MP3s, but that’s another debate for another day) through the playback mechanism of their choice… bravo for them and yay for music! I do take offense at folks with superiority complexes who turn their noses at technology that they think is outdated, strictly for the sheer joy of belittling other people. I have no qualms about precision where possible, and in many disciplines (as exemplified here on HAD) such precision is very much necessary. Finely controlled currents, voltages, pressures, etc… are very much necessary for a great many mechanical outcomes (including parts of playback systems where safety is necessary). But the arts (visual / tactile / audio) don’t require that level of rote adherence to precision, nor do they generally benefit from it. Music is subjective. Your own urge to discount/disclaim/diminish audio technology you believe to be inferior is antithetical to the subjectivity of music. That’s what I’m getting at.

          In the specific case of [Torque]’s comment, I should have just replied with something such as “flawed analogy” and left it at that. I apologize for suggesting what he should do with his phone. That was rude of me and I’m very sorry.

  10. I’ve been building and restoring tube gear for 20 years. I like it for a variety of reasons. You can actually see the parts of what you’re making, and know the technical functions when you look at them. Tubes are the simplest tech that will make music. You can drive an efficient speaker with a ‘spud’ a (a one-tuber) amp consisting of a high transconductance pentode, output transformer, a power supply and a hand full of passives. It’s a thrill to hear music from an amplifier that simple. I also like solid state amps and designed the Squelette chip amp for Make magazine. And of course discrete transistor amps like classic Accuphase also have a place in my music systems.
    But when it comes to voting with your wallet I’d give up any of my gear before my Heath W5-M tube power amps from the 1960s. Can’t tell you why but they always make the music sound wonderful.

      1. Yes, A La Pass, and I’ve made a few of those. Downsides: enormous idle current requirement and very high input capacitance unless configured as a source follower. So with a power MOSFET you can have gain with cruelly low input impedance or high input impedance and no gain.
        Yes, I’ve built a few, including hybrids with tube input stages.

  11. All of you all soooo entirely full of shit and apparently yourselves. I think the article was well written and helpful with those interested in tubes. Sure it states the authors opinion and he tries to back his thinking with more opinion, but it is just that. OPINION, it cannot be right or wrong.
    I own a home studio and I have tube amps, solid state amps, both solid state and tube preamps, DACs, Hybrid DACs with tube preamps, and software that is supposed to emulate solid state and tube equipment, and a good enough pair of monitors that I can tell the difference between all of them (software DOES NOT sound anything like real tubes or solid state amps… no matter how hard they try) and they all have a place. I like tube sound personally, but thats my OPINION. When you lend me your brain and ears, maybe I’ll agree with you that it sucks…

    1. Nicely put. I’ve got a fair bit of audio equipment too. I’ve got lots of solid state gear but my favourite amps are my EL34 50 watt mono blocks from a 1950’s design. They sound absolutely golden and I even managed to source a pair of Dynaco output transformers from the 60’s for them.

      As far as the haters go, I suspect the anti-tube group are the way they are because they just don’t know any better and it’s easier on their egos to hate what they don’t know..

      1. “As far as the haters go, I suspect the anti-tube group are the way they are because they just don’t know any better and it’s easier on their egos to hate what they don’t know.” LOL you do understand by replacing anti-tube with anti-solid state you would could have been describing tube fanatics for years, right?

        1. Yeah, except no….

          You see I don’t care whether you or someone else wants to promote their latest FET, gainclone or Class D design. In fact, I’ll read that with interest because I’m also interested solid state amplifier theory, design and discussions. My first amps (the ones I built) were transistor amps, then I messed with various chips, back to transistors and finally got around to building with tubes. My preference for my home audio is my EL34 mono blocks. They sound awesome. My favorite guitar amp is a fender twin which also has tubes but I do have a really nice solid state fender practice amp that I can play all day long because it sounds so nice.

          The difference with this “anti-tube” group is that they have made it abundantly clear in this discussion and others that they won’t stand for anyone promoting a preference for tube hifi. It’s as if even discussing why someone might appreciate tube sound is blasphemous of heretic.

          For me, it was at first shocking, then annoying (a little) but now it’s just kind of amusing.

          1. It is Funny, I don’t recall ever seeing pro-tube comments being made on any solid state amplifier discussion, but I see plenty of “anti-tube” comments on tube gear articles, it’s very unusual.

          2. Yup, that’s been my observation as well. I’m sure there are plenty of tube audio guys/gals who have strong opinions about solid state audio but I don’t see them polluting the discussion the way the anti-tube folks do.

  12. “…vacuum tubes do sound better than transistors…”
    You want annoyed readers?
    Because this is how you get annoyed readers (that have common sense).

    More crud like that I’ll be less inclined to read hackaday.

    1. So only those with your opinion possess common sense, and everyone here with common sense doesn’t know how to decode subjective statements?

      That’s what I’m getting from your comment.

      Perhaps you’d be better off starting your own blog where you can police statements of fact/logic/opinion to your own liking.

    1. Second and third harmonic distortions to vinyl balanced audio sounds blissful. Sounds like a logical statement of opinion to me; and one I tend to agree with. ;-) The white album, or Dark Side of the Moon next, man? and pass the bowl until you decide.

  13. Nice intro to tubes, sadly the bootlegging was misguided. Back in the day I bought a pocket DAT recorder and built my own Binaural microphones and battery box and ended up with concert recordings that are better than anything released by the bands.

    If you cant stuff it all in a small pocket and pass it all off as a personal music player you will never get past the bouncers or checkpoints.

    I still have friends asking for copies of my recordings of Joey Ramone in his last year live on stage at a CBGB

  14. I’m not sure I like where HaD comments are going these days. So many negative responses by people who have no experience in the field in the first place. Since when did this website start being read by people who talked out of their ass and not from experience. I am looking at all of you who are making comments that have never built your own audio gear or heard a tube amp in the first place, why are you regurgitating bs you read somewhere else instead of creating your own ideas from experience? There is a reason tube amps are still produced and enjoyed decades after tubes stopped being used and it’s not just nostalgia. DIY audio is really the first open source hardware hacking and making community that existed, it’s been around as long since radio was invented. What other industry can you look up the designs for a product built in the 30s and build a working version today? Need something more modern? Just look up Pass labs, Nelson Pass has been providing his designs to the industry for almost 20 years.

    I have built my own sub enclosures, speakers, RIAA preamp, Pass F5 SS amplifier, RLD tube amplifier, some class D amplifiers, JLH amplifier and more car audio systems then I can remember. SS and Tube amps, when designed well, sound amazing. The problem is that most SS gear that you can buy for a reasonable price is poorly designed. Tube gear, due to it’s simpler design requirements, tends to sound better because it is easier to work with in the first place. If you have never herd a well designed tube amp, you really owe it to yourself to go and seek one out or build one.

    1. Just because people have no experience in building them, does not mean they can give criticism (backed by arguments). Most people rightfully atrack the tone of the article, not its content.
      Also; just because its still being produced does not mean there is an actal (technically) good reason for it (that logic, same as your first argument is a fallacy).

    2. I’ve only seen a few comments suggesting that the opinions on the sound of tubes is wrong. You like it, some don’t, so let’s all listen to what we like! It’s the misstatements of “tubes always make better audio” or “solid state can’t generate that sound” that is complained about, because it’s just not right.

      And as for audio being the first DIY and open source field? What about HAMs? Or . . . something else that I can’t think of right off the cuff, but I’m sure there are other fields.

      Assertive, declarative, and factually wrong statements need to be shot down. Statements of opinion, we should all be welcome to our opinion on the sound of tube amps or anything else as long as we don’t expect everyone else to agree.

    3. It started when articles were written like something was magically better than everything else even when it clearly isn’t.
      This article is full of awful and blatantly incorrect bias, and I’m not talking about the noise kind.

    4. Hater’s gonna hate and ignorance breeds contempt. It doesn’t matter what the article is about; if it contains tubes, this odd crowd of anti-tube folks get their panties all wadded up and go ballistic. It’s a little annoying but also a little entertaining reading their tirades, imagining the steam blowing out their ears, faces bright red as they furiously type their rankings. I really think its because they haven’t a clue and to be perfectly honest the reaction is more than a little entertaining.

  15. May I suggest a cheep tube sound solution?

    I built this kit a long time ago it starves the tubes with 30 volts only no transformers.
    So if you like tube sound on the cheep give this a look over,also this was featured in some electronic mag years ago so a schematic may be available out there in the ether…
    I went the kit route,very clean until you “blend” in the tubes for some warmth in your sound…
    Oh the linky,
    Note: not affiliated with the company, just a one time happy customer…
    later napervillian

  16. That linked article put it well: tubes sound different. “Better” is a subjective term. Same with vinyl. They sound different, or they sound better to individuals. Clearly not to all on both accounts.

  17. Theater . . . T…heater, keep the house warm. I recently sold off a Tektronics tube scope that used to keep my shop warm in winter. Y’all have fun with those tubes, I will stay in this Millennium .

  18. The arguments in this thread are ridiculous.
    You can’t do your tax by candle light, and you can’t seduce a woman under fluorescent tubes.
    Every technology has it’s place.
    If you want high fidelity, efficient audio reproduction, use class D or BJT AB.
    If you want to colour audio, use tubes.

    The kinks used to poke holes in their guitar cab’s speakers for extra fuzz. Why? Because they though it sounded good.
    Perception is everything.

  19. Despite the over-dramatic arguing, the article caused its readers to engage in a discussion. When the people of the world stop debating and arguing innovation will disappear.

  20. Hopefully you’ll do a follow up HaD article on how to make your own purified crystal copper wires with special mono-directional electron channels for that uber clean sound we all want from our MP3’s.

  21. Experience? Lifetime professional electronics tech and musician, and I’ve been building and servicing band gear since valves (toobs) were the only game in town, 50-some years, but most of my work has been on solid-state so I’m no Hyper-Fi-natic infatuate.

    When it comes to *tenor guitar*, specifically and only, valves have the edge. Below clip solid-state rules, no argument, but guitar amps spend most of their operating life over clip and in that turf they sound very different. I wouldn’t use valves for anything else, my synth amp, home stereo, PA, and mic pre’s in particular, are all s.s., but for my guitar I use valves (with no NFB), and for that they are unbeatable – s.s. for clean, valves for dirt/”tone”.

    Many s.s. guitar amps have asymmetric clippers in the preamp and current feedback to lift the output impedance(!) to emulate valves and avoid output stage clipping.

    You want cheap and buildable valve guitar amps? Common and cheap 100V Line trannies for output, and stacked common and cheap LV trannies followed by voltage multipliers.

    HV power supplies;

    Guitar amp (e.g. 15Wrms, under $200);

    The valves vs. transistors war ended decades ago guyz.

  22. How comes that noone ever really talks about Class-T Amplifiers?? An SMSL SA-50 (there are other great products out there, this is just meant as an example) is super-efficient, has its own quiet warm but clear sound and is super-cheap. Of course you can also make your own selfbuilt T-Amp without spending a lot of money and it won’t sound worse than a good tube amplifier. A lot of tube fans really like these T-Amps, just look into audio forums.

    1. Hey Sam, The Class-T are actually Class-D (which a number of folks have talked about thus far). “Class-T” was a marketing name from the folks at Tripath (RIP) who created a proprietary improvement to the Class-D architecture and wished to have a trademark. It is not a true amplification class in and of itself. Wikipedia offers this:

      That said, I’ve owned a number of amps based around the TA-202x chipset, and the sound quality has a number of tube-like characteristics (and you can’t beat the space footprint!). My TV amplification is presently being done by a Dayton Audio DTA-1 ( ) into a pair of vintage Dynaco A-25s… incredible sound experience! I also tried the DTA-1 through a set of the much acclaimed Dayton Audio B652 Bookshelf Speakers ( ) … they’re not quite A-25s, but you don’t have to rummage around thriftshops and yardsales in hopes of finding a pair either. For under $85, that’s a solid audio combo (and the B652’s have a number of published hacks to improve their quality if you wish to go even further!).

      1. I need to find some little bookshelf speakers for a surround system I am trying to put together. I don’t mind rummaging through thrift stores and yard sales to do it either. Last weekend I picked up one of these for $10 at a yard sale

        I don’t know what I’m going to do with it yet, but for $10 I can strip it for just the jacks on the back and still be ahead of the game.

  23. Consider this… if some how solid state had preceded vacuum tubes and people had years to get accustomed to the sound of solid sate, audiophiles would have been saying solid state was superior to tubes all along.

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