The TTVJ Millett 307A Headphone Amplifier

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The AKG K1000 phones really require more drive power than most conventional headphone amps can deliver. In fact, the very best hearing of these cans for me happened at a Head-Fi meeting a few years ago where they were powered by an early Nelson Pass Aleph stereo amp coupled to high quality ancillary components. Any other attempt I could muster to make the K1000s sing always fell short; believe me, I have tried lots of things. The TTVJ 307A remedied that dilemma in my home. With digital playback there was more than enough headroom to play louder than would be considered judicious. My analog setup was less able to reach those high volumes, due to phono stage gain limitations, but it was plenty fine. The K1000s/307A combo offered an airy, wide and quite enjoyable soundstage, coupled to a balanced, tonally satisfying feel. The decay of notes was natural and percussion details floated effortlessly and accurately. I would have preferred a touch more deep bass, but these headphones are not famous for that characteristic, so I am not grousing. Todd’s amp provides dedicated jacking for this kind of specific implementation and that shows excellent foresight and creativity on the design team’s approach. One of the front panel connectors readily accepts the standard 4 pin plug which terminates the short run of wires from the K1000 drivers and a mere twist of the selector knob makes the appropriate circuit connection. This was the second best performance I’ve had the pleasure of hearing on AKG K1000s and this time it happened in the comfort of my own home. Bravo!

Staying with this same maker, I tried the AKG 701 phones in balanced configuration as provided by Todd. The sound was clean and had a charming delicacy, however, the overall impression left me a bit lukewarm. While there were no real nasties, the presentation was a bit bland and uninvolving. Bass was tight but also a tad light on everything I played. My prior exposure to the 701s was some time ago and of short duration, but I can see why some listeners would like that sound. There was more than plenty of juice available to drive the phones, by the way.

I’ve owned Sennheiser HD600s for several years and invested in the Stefan AudioArt Equinox cable upgrade with good results. Todd offered a set of those same cables but in balanced format so this was an instructive adventure, and the swap-out was easy and fast to achieve. In unbalanced mode the sound was smooth, rich, and warm with a touch of darkness that mainly impacts the top end extension. Vocals came across recessed and the forgiving qualities I have come to associate with these phones were certainly true with the 307A also. While this easy-going feel helps make it satisfying to do long listening sessions, the missing transparency and resolution can be of some concern on detail-laden music. Switching to the balanced mode was a radical improvement. Both frequency extremes benefited and openness was elevated in a striking way. Vocals were no longer so recessed and orchestral material was portrayed with a larger soundstage and greater clarity. Piano came though richly and spaciously [if recorded that way], with a sense of rightness that was not heard in the unbalanced mode. This was a real eye-opener for me, especially recognizing how well the 307A brought out all the good things through the balanced configuration.

In case I forget to say this, throughout all of my trials this amp behaved beautifully, never burping, farting or doing anything other than making for grand listening sessions. And, keep in mind that we are talking glass envelopes here. Incidentally, Todd is clear about having a proper supply of replacement tubes on hand for the future, and they don’t cost a fortune to acquire.

The Audio Technica ATH W1000 phones running unbalanced in the 307A yielded a sound which was lively and energized, offering some midrange lift that felt obvious especially on vocals and brass. These are not the most resolving or transparent cans in my collection but they are fun and easy to play with. I did feel some harmonic integrity was missing, but that is true with other amps, although the Yammy does compliment the W1000s nicely.

My Audio Technica L3000 phones are another animal entirely. They loved the 307A and delivered a warm, smooth, spacious full-bodied sound. Piano tone was outstanding and the heft of lower notes came through in gang buster amounts, minus any complications or problems. Voices were rendered in excellent balance relative to instruments and spatial cueing/ambience was super too. My listening notes included statements such as “a powerful sense of sweet musicality without hyper-detail annoyances’ and “truly beautiful listening”. If points were being awarded for what cans meshed best with the 307A, this combo would be a winner, just very slightly ahead of the Ultrasone entry.


Ultrasone Edition 9 headphones (photo above), made in Germany, are at the top of the heap of this manufacturer’s offerings. Well made, comfortable and serious looking, these are the headphones on which I do most of my listening at home. In addition to general listening, I use the E9s in critical audio editing work for high resolution recordings I make of local acoustic concerts, primarily from the classical genre. I consider these cans trustworthy, accurate and suitable workhorses for both applications and am very pleased to report that they performed beautifully with the 307A amp. In fact, bass reproduction with this combo was stunningly good. I didn’t know those E9s could perform that way from any prior usage. Space rendering was first class and this pairing may have brought me closest to what I enjoy most when listening to my main “big rig” loudspeaker system. Piano and vocal tracks were absolutely a joy to hear, and large scale orchestral material had a majesty and power that bowled me over. I should note that because there was this bounty of clean, extended bass performance my first reaction was that the top end was a bit scant. With further listening and a broadened range of music I was able to assuage that initial misapprehension. All was there and it came across most deliciously. Wow!

The Grado GS1000 balanced phones delivered a full, rich and energized sound. There was a bit of forwardness which made vocals stand out, perhaps with an overly strong feel. On certain peaks things felt on the edge of harshness, but that might be putting it too strongly. Both bass and high frequencies were very well articulated. However, the sense of space and soundstage was not as apparent as with the L3000s, E9s or K1000s. Percussion details were especially well served giving a feel of very quick transient response. Interestingly, tenor and alto sax recordings had a wonderful snap and the rendering of the musician’s tone, or lack of it, was readily obvious. I was quite pleased to see that the comfort factor of the GS1000s was superior to any other Grado cans I have tried.

The final pairing utilized the Sony MDR SA5000 in unbalanced configuration. The overall feel here was of clean sound, with a sense of forwardness similar to what I experienced with the GS1000s, especially on voice. Dynamic scaling was very good and freedom from any compression made the music jump. Tone, in general was a bit analytical and made me want more warmth, but there was nothing really nasty to have to bear. Bass was tight and punchy however, I felt it could have conveyed more resolution and deeper extension to compete with the bass performance of the L3000s or the E9s.


After these eight trials, what is the bottom line? Essentially that the TTVJ 307A amplifier is a marvelous device. It performs as one would hope … by getting out of the way of the music. The diversity of headphone styles and intrinsic colorations they possess were revealed readily. The amp’s ability to run challenging phone designs along side of easily driven cans was a major bonus. The only requirement of the user was to adjust gain and set the proper phone impedance, both of which were a snap from the front control panel. While I did not do a lot of listening with ear buds, the thoughtful inclusion of a jack setting designed for IEMs [in-ear monitors] allowed me to use my Etymotics ER4s and they did nicely in this configuration, if perhaps a bit too analytical sounding for prolonged listening.

The 307A delivered an articulate, refined, neutral and transparent sound, possessing high resolution with plentiful gain for all types of headphones, excluding electrostatics. I should reiterate that that this is a vacuum tube amplifier and it was a true joy not having to worry about hum, noise, snaps, crackles or pops along the way. I operated the unit as provided by Todd, but would guess that those folks into tube dampers, fancy footers and other such tweaks could try those accessories to their heart’s content. Knowing that the circuit blends classic design with modern components is reassuring, and from all that I could see, this amp will function superbly for a long, long time.

Hearing such broad, deep and expansive soundstaging from properly recorded discs was a treat unto itself, but coupled with the well extended frequency extremes, everything spoke well of the inherent capabilities of this machine. The midrange performance on just about every can used was remarkable. My guess is that this relates to the magic of the single ended design which is so successfully implemented here. I suspect the exotic transformers can’t be dismissed either.

It is a common observation that headphone listening creates that “in the head” perspective which can be disconcerting to some folks. Headphones that minimize that issue such as the AT L3000s, AKG K1000s and the Ultrasone E9s were revelatory for hearing just how well ambience and spatiality could be retrieved, particularly when the amplifier allows it to manifest so beautifully. Having just used a word that is not so common in gear descriptions, I think I can sum up this 307A review by emphasizing the beauty of the music conveyed by this amp. No other headphone amplifying device has allowed me to leave the fuss behind and feel so engaged and transported during this adventure in solo sound reproduction.

Congratulations Todd and Pete for a stellar product. Highly regarded and enthusiastically recommended.

Features/Specifications and Company Information:

TTVJ Millett 307A Headphone Amplifier
Single ended triode amplifier with transformer coupling
Balanced inputs and outputs
Precision stepped attenuator volume control
Point to point wiring above a solid copper ground plane
307A directly heated pentode output tubes used as triodes

Weight: 40 lbs. weight

Price: $5,995.00
Seller: Todd the Vinyl Junkie
P.O. Box 1335
Three Forks, MT, 59752