The Problem With Tubes

The Problem With Tubes

One thing I am sure of: expectations are premeditated resentments.

You can apply this maxim to anything, anytime but nowhere is it more obvious than in the exotic reaches of high-end audio. In audio, expectations become antipathies that divide audiophiles into stone-throwing tribes, like digital vs. analogue or tubes vs. transistors. Worst of all, expectations colour our views and cover our ears so we become unable to experience the true characters of rival technologies.

Last night I sat, alone, in my shadowy, candle-lit room, listening to an album called Djam Leelii by Senegalese musician Baaba Maal and blind guitarist Mansour Seck. The music itself – twin electric guitars, punctuated by bits of Afro drumming and some electric keyboard by Aziz Dieng – was sad and lyrical to an extreme.

I played both sides twice and tried my absolute best to concentrate on Maal and Seck’s flow and invention. But my mind kept wandering… to the sound in front of me.

I could not stop myself from observing and admiring the form and colour of the exotic energy dancing between the speakers. I must repeat for emphasis: I was admiring the form and colour of the sound energy pulsing in front of me.

Then I realized, this is what Baaba Maal and Mansour Seck (and their producer) intended. The beauty (and musical content) of these rare, once lost tapes is the tone, texture and form of the sound as it expanded into the room it was recorded in and now, as it pulses into my dark chamber.

Next I realized, that I had been noticing and admiring the quality of sound of recordings all my life. I realized also, S O U N D is beautiful. I believe all sounds have meaning and complex content – even farts and the backfirings of automobiles.

Yesterday at noon, I would have sworn I was only in audio for the poetry of music; but last night I realized that for fifty years I’d been using quality audio gear to listen to pipe organs, guitars, drums, marimbas, banjos, accordions, flutes, harmonicas, and singers from all nations – mainly because I enjoyed the sound (and the pulsing vibe) of people singing and playing instruments. That must be why I never paid much attention to song lyrics. I felt liberated to finally accept this about myself.

I realized also that the quality of the sound I was admiring was a direct result of the audio system I was using.

Silhouetted by candles were my 1984 Linn LP12 turntable with an SME arm and Koetsu Rosewood Signature Platinum moving-coil cartridge. The ancient Linn was feeding a tubed Tavish Design Adagio RIAA phono stage, into a PrimaLuna Prologue Premium tube preamp and a 100W Rogue Audio ST-100 all-tube amplifier, which was easily and effectively driving Harbeth’s M30.2 monitor speakers. This all-tube system is one of the most succulently enjoyable systems I have used since I started at Stereophile.

The next morning I wondered how much of my late night pleasure was caused by all those vacuum tubes. On a whim, I asked my Facebook friends, “Why is tube-fired audio still so popular?”

The first response was, “Tubes are more popular during the’s romantic, always sounds good and keeps you focused on the music played.”

Not unexpectedly, Stereophile Deputy Editor Art Dudley nailed it in one sentence. “For the same reasons that cooking with gas stoves still appeal to most serious cooks: newer and supposedly better technologies simply fail to give the same results.”

To which I responded, “Objectivists would say 1600-degrees is 1600-degrees – right?” Later, I added, “This notion of fire is very interesting – I never thought of it, but the same piece of meat or vegetable (or pizza) will unquestionably taste different based on what type of heat (wood, coal, gas, microwave, etc.) is applied.”

And of course Stereophile Chief Editor John Atkinson said, “Underdamped low frequencies; and heavy on the second-harmonic sauce.”

Which reminded me, isn’t that why they invented feedback?

My friend David MacPherson said, “Who doesn’t like magic?”

Stereophile contributing Editor Jim Austin reminded my Facebook friends that, in his interview, solid-state amp designer Nelson Pass, said, “…the economics of tube circuits enforces a discipline of simplicity, where it is not convenient to achieve quality by throwing lots [of] parts and feedback at the problem. You will not see 50 tubes and 80dB of negative feedback under the hood of any tube amplifier.” 

To which I laughingly replied, “Less correction = more affection?”

Another friend Richard Johnson said, “…a certain 3-D midrange capability I don’t really hear in solid-state.”

Brian DiFrank of Whetstone Audio said, “Because Class D sucks.”

Analog Planet’s Michael Fremer said, “For the same reason tube microphones are (preferred) – especially in the digital age.”

In his usual erudite fashion, my runnin’ buddy, turntable setter-upper Michael Trei said, “The same reasons most people prefer cotton over polyester, stick shift over automatic, butter over margarine, film over video, and mechanical over digital watches.”

My brother, amplifier designer J.C. Morrison said, “The vacuum tube amplifier reveals a secret of the universe in its operation. You see it happening! Its simplicity of operation allows an electrical simplicity, one that requires less changes of state, less translation and transformation.”

Jazz drummer Billy Drummond said, “Purity of tone.”

A non-audiophile friend said, “Because they sound warm.”

I have heard that last line a million times, and I’ve been playing music through tubes all my life, but I’ve never heard tubes sound “warm” – except maybe a Fischer 500 receiver playing some acoustic suspension speakers by AR or Advent; speakers engineered for the cheap watts and the feedback-fueled high damping factors of solid-state. Remember those Japanese receivers with 0.00000001% THD that burned the hair off your ears?

My experiences as both an amp builder and critical listener inform me: tubes don’t have a sound. Overall, vacuum tubes (especially triodes) are more linear in their transfer functions than silicon devices.

The reason JA says, “Underdamped low frequencies; and heavy on the second-harmonic sauce” is because designers of tube amps are less inclined to sabotage the musical potential of glass and fire with textbook amounts (20-50dB) of feedback or degeneration.

Tubes do not have a characteristic sound. Feedback does. Amplifiers with excessive feedback sound hard and un-supple. Dry and tight. Like (surprise surprise) – solid-state amplifiers!

The most naturally linear power amplifier output devices are directly heated triodes (DHTs), which, fortunately, do not require feedback to reduce distortion and lower their impedance. Instead of feedback, DHTs use output transformers to reduce impedance and couple them effectively to loudspeaker loads.

To my ears, amplifiers with low or no doses of feedback saturate the male and female vocal rage with rich tone and high levels of tactility. Amplifiers employing low or no-dose feedback deliver supple, bendy high-plasticity forms. Slightly larger doses tighten things up and raise the damping factor. Adding more than 30dB sounds like dragging a tin bar along a brick wall.

Tube amps don’t sound warm: low-impedance insensitive loudspeakers with weak magnets, long-excursion drivers, and complex highly-reactive crossovers, sound warm and compressed with soft bass – when driven by low-feedback (tube or solid-state) amplifiers with high-output impedances.

Reality is: well-designed triode, JFET, MOSFET, or SIT amplifiers – with minimal feedback – sound pure, neutral, and beautifully transparent (maybe even magical) driving high-sensitivity loudspeakers with a high, flat-impedance characteristic.

Forget warm tubes and tight transistors. The problem with all amplifiers is this: lazy loudspeaker engineers who would rather spend manufacturing money on heavy, shiny cabinets (for perceived value) than expensive wide-range drivers with powerful magnets (so amplifiers could use less feedback). Therefore…

My question today is: if we all want beautiful, palpable, realistic sound, why do we accept and admire expensive current-hungry loudspeakers with power-sucking reactive crossovers and bass impedances below 2-ohms at phase angles of -45 degrees?

In my next instalment, I will discuss loudspeaker cartels, headphone manufacturers, and the latest rebirth of no-feedback amplification.

Anton's picture

Quote Herb: "Yesterday at noon, I would have sworn I was only in audio for the poetry of music; but last night I realized that for fifty years I’d been using quality audio gear to listen to pipe organs, guitars, drums, marimbas, banjos, accordions, flutes, harmonicas, and singers from all nations – mainly because I enjoyed the sound..."

Quote Guru Mejias: "I like listening to music, on the Hi Fi."


Regarding tubes: Tubes are more mindful to the present, and serve the ephemeral nature of music better.

Tubes are not static or fixed.

To paraphrase the famous audiophile, Ajahn Chah, "As we sat listening, before saying a word, he [Ajahn Chah] motioned to a tube amplifier on his shelf. “Do you see this amplifier?” he asked. “I love this amplifier. It plays music admirably. When the sun shines on it, it reflects the light beautifully. When I tap it, it has a lovely ring. Yet for me, this amplifier is already broken. When the cat knocks it over, or my elbow knocks a tube out of whack, or when it fails after a time of beautiful service to the sound and goes silent, I say, ‘Of course.’ But when I understand that this tube amplifier is already broken, every minute with it is precious.”

DH's picture

Technologies don’t sound good or bad. Implementations do. You write as if the love of tubes is universal. It’s not. Some prefer good SS and actually think it often sounds better. And guess what? Some people even like the better Class D amps and think they sound good - and don’t make silly generalizations like “it sucks”.

kenmac's picture

I always learn so much, and enjoy so much, your writings on all things audio!

Ortofan's picture

… exhibits a surfeit of second harmonic distortion reminds me of watching a TV set that has had the controls turned up so far that the colors all appear surreal, rather than real. Calibrate the display so that the color levels are correct and the resultant picture quality, in comparison, can appear relatively dull and lifeless. The same could be said of the choice to add reverb to a vocal track when making a recording. It may sound “better”, but it’s not the singer’s natural voice you’re hearing. Make a tube amp with inaudible levels of second harmonic distortion and see if it still has that “magic” sound quality. If you prefer having your sound reproduction system add an extra dose of "magic" to the music, that’s fine - but don’t fool yourself into believing that it’s somehow more true to the source.

On the subject of feedback, its use does help lower the amplifier’s output impedance so that interactions with the varying speaker impedance can be reduced to inaudible levels. Is there any tube amp that can match that performance? The Hafler DH-200 amps you once had were not a low feedback design. Did you not like their sound quality? Have you tried one lately – especially with your Harbeth speakers? If not, find a used one that hasn’t been modified, replace the electrolytic caps with new ones – there are only six, so it’s a simple job – and then have a listen. Another amp to try would be the Benchmark AHB2, which has vanishingly low levels of noise and distortion. Or, you could try one of the more recent solid-state amps from QUAD, which is supposedly what Alan Shaw uses during the development of his Harbeth speakers. Then you would be hearing the 30.2 speakers in a manner much closer to what their designer intended.

Herb Reichert's picture

and kit built every Hafler amp - except the DH-500, which, I have imagined was the best of the lot. All those Haflers sounded fine into the soft Large Advents I was driving. When I gave the Advants away and bought, first, a pair of Altec 604Bs, then shortly after, a pair of Rogers LS3/5a the Haflers sounded horribly hard and (worst of all) FLAT! This was in comparison to a small class-A amp by Andy Rappaport and a Marantz 8B -- both of which (to me) made the Rogers sound divine and Haflers sound like a bad Japanese recover. If you have ever experienced a Bedini 20/20 or a Levison ML-2 you will know what I mean.

Ortofan's picture

... philosophical question once raised by David Hafler: Should an amplifier be pleasant sounding, or should it be accurate even if accuracy is not as pleasant?

Was it that the Hafler amps that made the sound "horribly hard and (worst of all) FLAT" or was it an inherent characteristic of the recording? Did the Rappaport and Marantz amps perform as well as the Hafler amp on a bypass test? Or, were they adding something to the input signal that made the sound quality seem more appealing?

A number of the Stereophile reviewers reside in the NYC area, such that they could probably arrange to gather in one location for a group listening session. What I'd like to see is to have those listeners conduct a comparison between the Benchmark AHB2, which seems to exhibit the lowest levels of noise and distortion of any amplifier - and is thus likely the most "accurate" amp, and (for example) the Audio Research Reference 150, which is probably a good example of a "pleasant" sounding amp. The results should make for an entertaining story.

(As a side note, the Hafler amps - at least the early production
DH-200 I had - tended to be slightly under-biased as shipped from the factory. Did you ever try increasing the bias level on your amps?)

Everclear's picture

Hi Herb ........... Could you please review the new ST-70 Hafler/Dynaco re-make tube amp, for Stereophile (with measurements)? ......... Thanks .........

jond's picture

Well stated Herb. I enjoyed reading it as I sit here listening to a tubed dac through a tubed preamp to a tubed amp. Sublime through my Audio Note AN-J's.

bigrasshopper's picture

Ten years ago I was taking my first unsure steps into the deep end of audio, I took special note of some who bemoaned the fact that it took them half a lifetime of buying and selling to finally feel they had a system they thought they could live with. “ If only I could have started out with this system, the thousands I could have saved“. I puzzled over that. Was that possible, is it possible to read articles visit some showrooms and make a “ life choice “ ? I felt the pressure. The dealer who ended up supplying my system said to me as I was taking my leave from my first visit with him - “ whatever you do, stay away from tubes ! “ as if they led to the Dark Side. It did make sense to spend my money on something that would prove a reliable investment. Now it seems that perhaps it was because of my insecurities that I stepped into a system of large heavy speakers that needed lots of current, with solid state high feedback amps and a solid state preamp from the same manufacturer.
But ten years down the road, this year was the year though that I actually feel like I made a choice rather than a safe bet and am starting out again on an audio journey. But because this is a one step at a time journey, one that will probably take half a lifetime, it’s an incremental change. I swapped out my preamp for one with 14 tubes and a bank of large caps and output transformers. But because I still have my power eating speakers I opted for their six hundred watt solid state mono amps.
I spent twice the money but do have a system that sounds more than twice as good, it’s...its, as Dr Frankenstein exclaimed “ ITS ALIVE “. Mostly that’s due to the new preamp. I know that because during the summer I had to switch back to my smaller two hundred watt monos because of heat issues. It’s still big, it’s still balanced. I don’t know that I’ll ever end up with an all tube system, but I have learned something and still have a long road ahead of me.
I don’t really know what your system sounds like but I enjoy your writing, in fact I might go out on a limb and say that I tend to prefer the writing of people that listen to tubes, though that’s not entirely true. I didn’t say that. But it makes me wonder if there’s a correlation between certain emotional insecurities and a need for high volumes and deep base. It does provide a certain undeniable physical connection.
All other things being equal, I’m not sure I could give that up, unless of course I no longer felt the need for it, but it is the foundation of the audio band. One could argue that the middle is the audio foundation, psychologically that makes sense but I won’t invite an argument.
It would be remiss of me not mention that from day one I’ve been hearing clicking sounds from the signal portion of this tube preamp. It’s under warranty but I keep delaying sending it back because I’d hate to be without it.

Steven Plaskin's picture

Charley Hansen of Ayre Acoustics believed in zero-feedback designs for his solid state amps. Incidentally, they have no problem driving the type of speakers that you question.

Boy Howdy's picture

There are differences between different kinds of fuels for cooking that are VERY important for the cook and perhaps whoever is consuming the results. For example, how quickly a cook can adjust the heat is one of the primary reasons why most cooks prefer gas - if you are making a custard and you do not want to scald the milk, controlling the temperature virtually immediately is necessary and definitely effects the flavor and consistency of the custard. So perhaps it is just the metaphor that is ill-fitting for a comparison of tubes and solid state? No, that's still too narrow a perspective. As a musician, there are many aspects of a recording that I listen to (and have for over 50 years) not all of which are always "better" on tube OR solid state. For example, sometimes I am listening to the melody, sometimes the strength of the attack(for string instruments), sometimes the phrasing of the vocals, etc. Having the ability to switch from solid state to tube can be very illuminating.

I guess my real point is that tech versus "the music" is not a sufficiently broad perspective from which to philosophize about music or tech...

All the best,

blang11's picture

I come in at the opposite end of the spectrum. My system is all digital, solid state, with class D amps (the same Bel Canto Ref600ms Herb positively reviewed), DSP and a subwoofer. Certainly not the pure, low-powered system extolled here. I’m happy with my system and will stick with it for some years to come. That said, before upgrading any further, I’d want to be absolutely certain I want to stick with this system “philosophy”. I need to really expose myself more to a well-designed analog, tube, high-sensitivity rig.

nick's picture

I have had 2 major wow moments/revelations in the 30+ years I have been chasing better sound:

-hearing single point source speakers, and being blown away by the coherence
-hearing a tube amp for the first time, and realizing that no SS amp will do anymore

tubes (especially single ended DHT) just sound more real to me. I don't care if its a trick or illusion.

dalethorn's picture


Everclear's picture

If tubes are not doing something right, they would have been gone longtime ago. Same thing with turntables and vinyl records .......... Even with headphone listening some people prefer tube equipment and vinyl records ......... It was already mentioned that tube equipment is used in the recording industry ........ As I understand, some recording engineers are still using analog tape for recoding .........

Everclear's picture

To add to the above ........ Tubes (sauce) somewhere along the audio chain make everything taste (heard) great and more ful-fillig .............

Everclear's picture

Talking about complex sounds (HR talks about) ........... Severals months back Sound & Vision magazine had an interesting article (written by Ken Pohlmann) about different complex sounds, and how Harley-Davdson tried to patent it's unique sound of the engine (exhaust) ........

Robin Landseadel's picture

"My question today is: if we all want beautiful, palpable, realistic sound, why do we accept and admire expensive current-hungry loudspeakers with power-sucking reactive crossovers and bass impedances below 2-ohms at phase angles of -45 degrees?"

Who you callin' "we" . . .

I want beautiful, palpable, realistic sound. Fortunately, I own a Martin dreadnought. Recorded music I assume to be a simulacrum in all circumstances. I don't need to be fooled into thinking it's the real thing, my ears tell me "Poker Face" is a simulacrum without an object. I want the hyperextended unreality of Lady Gaga's memetic soundscape to be projected with irrational exuberance.

As regards your question, my answer is: notice how big the audio category of "personal listening" [headphones and their ilk] has become? It's a "thing", a musical experience that swaps out a lot of the "real" [other people, room acoustics, social interaction] in favor of specific musical elements, like the lack of room reflections producing a more musical bass. To your question—no current hungry loudspeakers, no impedance dips below 2 ohms, no weird phase angles. The unreal purity of headphone listening is the strange attractor for folk like me. I can't get right next to the performers at a concert, but I can with cans.

I know tube sound high and low, Neumann classic designs included. Transformers are the culprit for much of that "warmth" folks assign to tubes. For a decade my daily driver involved a set of Stax earspeakers with a hybrid tube/JFET energizer/amplifier. The triode output was direct-coupled, no transformers. I've owned Dyna 70's, a Marantz 8b and one of those Fisher receivers, have an old Scott integrated amp sitting in the garage that did amazing things with vocals til it gave out. But the resolution of the Stax amp might as well be on another planet compared to the ringy smoothness of those classic tube designs. Fat, smooth, warm—sounds we're talking about like comfort food, if you ask me.

Which brings me to this very interesting headphone amp. The Schiit Magni 3 has insane bandwidth specs, being something like 3db down at 2hz & 1mhz. The Magni 3 reminds me of the sound of the Stax amp, but with more resolution and a lower noise floor. Considering that it's $99 [plus shipping & tax], this is an audio miracle. Again, "real" doesn't apply to most of the music I listen to these days. But Beautiful? Palpable? Engaging? Fun? The Schiit will do all that on the cheap.

And if I want to hear the real thing there's always that Dreadnought, waiting to be played.

OneCreativeMan's picture

Tell me about tubes. Bought these NOS Mullards for my amp, (foolish late night overspending) didn't like em, then did, then didn't. The original modest tubes sound better, give me more smiles, made me stay up too late playing the same album over and over. Fun, so much fun!

My old mismatched drums, 60s era orphaned instruments all hot glue patched and old heads tuned, they bring me joy. So does my vintage cracked Zildjian ride cymbal. Epoxy and a ball peen hammer artistry!

My amp's tubes are inside case, no hypnotic glow, but I know what's in there... and I feel the magic

Love your writing Herb, it's medicine.

rl1856's picture

Why do we still listen through tubes ? If it ain't broke, don't fix it. Newer isn't always better. Cliches and truisms aside, it was once explained to me that a preference for tube vs ss may come down to a preference for even order vs odd order distortion. Our hearing mechanisms are more sympathetic to even order distortion. Tubes excel at even order while SS delivers lots of odd order distortion. As for me, I type this listening to net radio streaming through a restored Fisher 400 receiver in a secondary system. My primary system incorporates a SET 845 amp. Oh- and I use a fountain pen, wind up watch and soap/razor on a daily basis.

rt66indierock's picture

"My question today is: if we all want beautiful, palpable, realistic sound, why do we accept and admire expensive current-hungry loudspeakers with power-sucking reactive crossovers and bass impedances below 2-ohms at phase angles of -45 degrees?"

Some people don't accept them, I don't. The people who do accept these types of speakers are audiophiles that editors, reviewers and marketing types can wake up the voices in their heads. Just like you wrote over twenty years ago.

Genez's picture

Class D done right... and with a tube preamp.... I find sounds more real than a tube preamp with a tube amp. I listen with a NuPrime ST-10 that was TDSS modded... Using a simple Pro-Ject RS Box Preamp even with its OEM power supply.. Unfair to judge class D as if all Class D is the same. The NuPrime was designed with tube sound in mind, but without the weaknesses in tube amps when driving speakers. To each his own... I used to have a Mac MC275.

bgiliberti's picture

With my Harbeth 30.0s, I use a CJ tube preamp and a CJ SS power amp. I found this worked best. I like the added punch the big SS amp brought to the sound.