July 2013

Triode Lab EL84TT Integrated Amplifier
A very linear unit with impressive focus plus deep and defined soundscape.
Review By Rick Becker

  A four door sedan, older but rust-free, pulled into the driveway. A young man jumped out, picked up something from the back seat, and then hurried to my front door. It was Carl, from Toronto and in his hands was the small integrated amplifier he said he wanted me to listen to — no box, no manual. "Keep it as long as you wish," he offered. Just send him some feedback. Within a few minutes he was pulling out of the driveway, heading to Albany to see his girlfriend or something, having only enough time to let me scribble down the various transformers and unlabeled toggle switch functions on the back of an envelope. I remember being that young with so much vitality, when life had such urgency and time went by so slowly. But that was a long time ago. These days, time flies by with too many balls in the air — one of them an unwritten obligation to pay it forward.

It is a humble looking amp — something like a cross between a Manley Stingray and an old ham radio my father might have built back in the 1940's. Four little EL84 power tubes form a line between the two output transformers on the left and the power transformer at the back right corner.  A pair of 12AX7 preamp tubes guards them in front and a GZ34 rectifier tube stands off to the right by the choke transformer. The playing field is wide from left to right and shallow from front to back as if it were designed to sit on a bookshelf. At first I thought the two knobs on front (input select on the left and volume to the right) would look neat if they were wood, kind of like on some Blue Circle amps. But after living with it a while, the anodized aluminum seemed in keeping with the "form follows function" integrity of the design. A little toggle switch is placed right between the output transformers on the left to switch from 4 to 8 Ohm speakers — right where it needs to be to keep the signal path short. Black transformers on a beige folded aluminum chassis with silver knobs give it a conservative, technical look that a guy could appreciate. If it needs to be in a more decorative color, I saw three Triode Lab amplifiers at the Montreal show recently that looked a bit more fashionable. They could probably accommodate your request. This is a small company and these are bench made products. The manual, which was eventually sent to me, suggests that a cage is available if little children are in the environment. You may also want to put a drop of nail polish in the dot on the face of the knobs to better identify their relative position. Other than that, I really became fond of the basic appearance which suggests that they put their money where the sound quality needs to be.

Listening
Obviously this is a low powered amplifier so I started out with it in my TV rig. My "home theater" consists of an antenna, an LCD TV, an inexpensive Blu-ray player, a vintage Tandberg 3012A integrated amp and a pair of Coincident Partial Eclipse II speakers which are relatively efficient and tube friendly. The Triode Lab amp drove the speakers with sufficient volume when playing discs, but it barely made the grade when fed an analog signal from the TV's headphone output. Listening to CDs on the cheap Blu-ray player the music was acceptable, but being prone to tweaking, I slid a Symposium Acoustics Isis shelf under the Blu-ray for a modest improvement. Then I went to an absurd extreme and put the $550 Stillpoints LPI record weight on top of the $125 Blu-ray for a very noticeable improvement, but this is an unlikely upgrade path. More cost effective was my next move to put Boston Audio Designs TuneBlocks under the amp. The rig was singing very nicely, now. The point here is that the Triode Lab amp makes a very nice starting point if you are seeking to emerge from mid-fi into high-end.

When the manual arrived I learned that the amp only produces 6 watts per channel into 8 Ohms. Fortunately the unit operates in Class A with auto-bias and these are tube watts, not solid state. I thought I had been dealing with about 12 watts per channel. This was a game changer, but certainly not an end game. It means you will be limited to reasonably efficient speakers in a dorm room or den, or be forced to use very efficient speakers in a larger room, particularly if you are in the head-banging stage of life. I chose to seek more efficient speakers although either path is acceptable. This meant another attempt to land a pair of Zu loudspeakers for review. As luck would have it they had just introduced their new Union model with coincident tweeter and mid-woofer that boasted 99dB/W/m efficiency with 8 Ohm nominal impedance (5.5 Ohm minimum at 300 Hz). At $3000 this could be an ideal step-up from mid-fi to entry level High End. The only problem was that I had to wait. Since Carl wasn't pounding on my door, I waited.

I have no shortage of other things to do, but I plugged the Triode Lab into my big rig anyway. It is a large room (6000+ cubic feet), but my Tube Magic monoblocks play loudly with only 18 watts apiece, so maybe if I didn't crank it too loud I could get by. And "get by" is just what happened. As long as I kept the peaks at about 85dB at the listening chair eight feet away, my tube-friendly, 89dB Kharma speakers played quite nicely. We're not talking wide dynamic range or tight fisted bass at this volume, mind you, but this should be sufficient for dorm and apartment use or for situations where young adults don't want to wake sleeping neighbors or sleeping babies. Folks in the latter situation might be better advised to join the headphone revolution now in progress.

Production of the Zu Union speakers was delayed two months and they arrived just before we were to leave for the Montreal Salon Son & Image in the latter part of March. I wired them up in the home theater rig and Linda programmed the Blu-ray player for "repeat". By the time we returned two days later, the Zu had memorized every song on Melissa Etheridge's Brave and Crazy. But even then, they were far from broken in, so I left the Zu in the TV rig while I pounded out my Montreal show report over the next two and a half weeks. After that, taxes took precedent over music, followed by a trip to the semi-annual High Point Show, the world's largest show for home furnishings. By late April I was able to confidently set up the EL84TT with the Zu Union speakers in my dedicated listening room. While some may cry "foul" for substituting two components at once for review, I'll say right up front, there was a lot to be learned.

Oh my, it is amazing the difference 99dB/W/m efficiency makes for a speaker! We all know the first watt is the most important one, but an amp must have sufficient power to drive a given speaker in a given size room. On the EL84TT silence occurs with the volume knob set at 7 o'clock. Actually, without any music playing, dead silence occurs anywhere from the 7 o'clock to the full-on 5 o'clock position. This is an extraordinarily quiet amplifier, which suggests than everything you hear when playing music is just the music itself or noise originating in the source components. In the listening chair I would measure 90 to 95dB peaks with my Radio Shack analog meter when the volume was set to the 10 o'clock position. Turning it up to midnight, I would measure 100 to 102 dB peaks. The point here is not that I like to listen at high volume, but that the Zu is an exceptionally easy load for an amplifier and the 6 wpc EL84TT was plenty sufficient to drive it, even in my large room. In fact, Carl at Triode Labs tells me that some of his customers prefer the Triode Lab 2A3 power amplifier to their 300B or EL84 amps when using the very efficient Zu speakers.

It was apparent from the beginning that the TT was a very transparent amplifier. We're talking about short signal paths using Mundorf capacitors on a tidy circuit board. Everything was in focus from bottom to top which was quite a departure for me. My Kharma are a little soft on the bottom and more laid back on top in spite of the much larger transformers in the 18 wpc Tube Magic amps. The Kharma also have a complex crossover molded into the bottom of each speaker while the Zu has practically no crossover in comparison, making them an easier load for an amplifier.

The TT uses two EL84 tubes per channel. This tube is familiar to me from my early audiophile days with the Manley Mahi monoblocks. It is a reasonably wide band linear tube from top to bottom. The 300B tubes in the Tube Magic get a little soft on the bottom and a little recessed on top, but have a glorious, holographic midrange for which they are revered. In comparison, the EL84 is closer to live music, but not as emotionally engaging as the 300B tube if you will allow me some generalities. Interestingly, the Manley Mahi with four EL84 tubes per channel allows the user to switch from 40 watts in ultralinear configuration to 13 watts per channel in triode mode. (I would usually use it in triode mode.) The Triode Lab does not offer that option, producing only six watts from two tubes for each channel in triode mode. The circuitry is not exactly single ended triode, however, but rather a push-pull design with their invention they call "Single Ended Approach Driver." On their website they call it "a one-stage SE-type driver topology... designed to work and sound like a real Single Ended amp. The music signal is directed straight into the circuitry with the least phase shift, noise and distortion possible." Quiet, it is.

As I said, you do not get the glorious, romantic midrange of the 300B tube, nor do you get warmth of EL34 tubes. Instead you are presented with a more linear signal with greater focus from top to bottom, yet with a deep and very well defined soundscape filled with all the spatial three-dimensionality that is present on the recording. Back-up singers are out in the front lawn, orchestras fill the room behind the speakers and extend out into the shrubbery with a diorama that is deep, wide and tall. The perception of height is aided by the vaulted ceiling, quite likely. In my room, with the Zu speakers, I felt like I was about 1/3 of the way back in the hall. With the volume set at 10 o'clock I had peaks of 102 dB with the opening minutes of Mahler's Fourth movement of the First Symphony. With rap music I had undistorted synth drumbeats right in my chest. With Chinese drum music I had undistorted bass down to the lower limit of the Zu Unions — about 40 Hz, after which the bass gracefully disappeared rather than present a muddied semblance of the lower frequencies that should have been there. No trouble with electric bass in rock music at all with this setup.

The treble had a lot of energy with the Zu Unions and was reasonably smooth as far as my aging ears could tell, although I've certainly heard greater resolution in much more expensive speakers. The linearity afforded by the EL84 tubes in combination with the Zu Union made the cymbals more prominent than my reference rig which caused a problem until I had the speaker positioning sorted out by bringing them closer together and tilting them back a bit. String instruments soared and female voices had a transparency and effortless presentation that escapes my reference rig with less efficient speakers, but three-part harmony did not have the pinpoint imaging afforded by separate monoblocks.

Over weeks of listening, the elevated treble became too tiring for long term listening (more than an hour at a time) so I thought I would check out my Manley Mahi with the Zu for comparison. This required reverting to my Coincident Statement preamp, a $5500 unit that received my nod for a Blue Note Award in 2010. With the Mahi monoblocks, the high level of energy in the treble was reigned in, leaving a somewhat darker presentation overall. However the focus and pinpoint imaging improved as you might expect by switching to monoblocks. And the bass tightened even further with more slam as you would expect from the greater power of the Mahi. I should also point out that my Mahi have been treated with AVM (Anti-Vibration Magic) on both the tubes and circuit boards and have noticeably better focus than stock models, which now go for $4600.

Mundorf Versus Jensen
I had several email exchanges with Carl about the high energy level in the treble I was experiencing with the Zu. He told me that the reason was the combination of the Mundorf ZN tin foil audiophile caps used in the TT which tends to unleash the high frequency when used with Zu speakers. Frequency response of the TT is listed as +0, -0.2 dB @ 1 watt from 20-20,000 Hz. With most audiophile speakers the top tends to drop a bit and the elevation of the highs is a benefit. For customers with Zu speakers he can offer the TT with Jensen caps which give a fuller midrange and bass, but slightly attenuated highs. As I mentioned above, he also said many of his customers with the very efficient Zu speakers have found great success with his 2A3 amplifier equipped with Jensen caps which rolls off the high end somewhat. (My Tube Magic monoblocks also use the Jensen caps, which is probably why the elevated treble was so noticeable with the TT/Zu combination.) With half the power of the TT, I expect the 2A3 would not have as tight a grip on the bass but given the reputation of the 2A3 SET tube, I suspect the glory of the midrange would make up for the weaker bass. He offered to send me a 2A3 amp for comparison, but with the delayed arrival of the Zu speakers my reviewing schedule was already backed up — not that I wouldn't love to hear it.

TT With Coincident Partial Eclipse II Speakers
Having admired the TT in combination with the Coincident speakers in my video rig, I hauled the Partial Eclipse II into the listening room to pair them with the TT and my digital reference front end — a Calyx DAC 24-bit/192kHz fed from a vintage Sony ES player as transport with an Audio Sensibility digital cable. This speaker, now retired from production, is rated at 8 Ohms (min. 7.9 – max. 10 Ohms) with a sensitivity of 92 dB/W/m. Power requirements were stated as 7 to 150 watts, so driving it in my large room with only 6 watts was pushing the limits. The presentation benefited considerably from having the speakers 54" out into the room, unlike their usual position in the video rig.  As long as I kept the volume modest it worked quite well. The most notable difference, compared to the Zu, was the darkened soundscape, a consequence of the attenuated highs in the Coincident (relative to the Zu), accompanied by a fuller midrange and bass. A slight loss of focus was also apparent, as well as a loss of dynamic contrast due to the minimal power available. But the music was also more relaxing and emotionally involving. At first, it felt like a giant step down in quality, but within a half hour, I felt like I was getting reacquainted with an old friend. The point here is not that one speaker is better or worse, but that your end result with the TT will be dependent as much upon the speaker as upon the amplifier. Hopefully, you already knew that. The experience also convinced me that a 92dB speaker with tube-friendly impedance will work quite nicely with the TT in a more typical room of say 3000 cubic feet.

The pleasure I achieved with the Coincident in the rig led me back to the Zu to try a trick that was suggested by the guys at Zu when I first took delivery. By tilting the Zu backward by extending the front spikes further from the cabinet, I was able to aim the tweeters a couple of degrees above my ear level (while still keeping them aimed straight ahead). This took the treble energy down a notch without effecting the focus or transparency and made it more listenable over longer periods of time. But the big realization that came to me after listening with the Coincident speakers was that I had been listening with the Zu at a much higher volume than normal. With my reference Kharma speakers and Tube Magic amps I would typically listen in the 85 to 92 dB range, but with the transparency and focus of the Zu, the volume crept up into the 88 to 95 dB range, and sometimes even higher. This is testament to the low noise factor of the TT amp and the high efficiency of the Zu speakers that permit high playback levels without noticeable distortion. No wonder I was becoming fatigued! Turning down the volume to my normal safe listening level eliminated the fatigue but also cost the music much of its drama and immediacy. But let's face it, much, if not most live music is louder and more dynamic than the level at which we listen at home. The good news is if you want to replicate the volume levels of a live performance, you can come pretty close with the Zu and the six watts of the TT. The other good news is that it will probably sound more transparent and in better focus than most live venues, unless you're blessed with an unusually good theater such as we have here in Rochester.

Getting It Right
It may seem like this is becoming a review of the Zu speakers, but the take-away here should be that the EL84TT's performance will be critically dependent upon the source, the speakers and the size of the room. This is the case with any rig to some degree, but when you get down into the low power tube amp league, system matching becomes more critical. If I owned Zu speakers and had them in a large room, I would certainly give weight to Carl's experience with the Jensen capacitors. If the room were medium size or smaller I would definitely consider their 2A3 amp with Jensen capacitors. But with other high efficiency speakers such as the Coincident or possibly some of the affordable Tekton Design speakers, the EL84TT should be a terrific fit with the Mundorf caps as standard.

Value
I took a big gulp when my friend Tom let the cat out of the bag and inadvertently told me the price of the TT. To look at it, I thought it would be less, but to listen to it, the price seems on target. It is limited by having only two inputs via RCA, although they can add a third input at an additional charge. The color combination of my sample is rather austere and technical looking. The Hammertone powder coated wrinkled paint is durable and is said to minimize chassis vibrations, but a quick trip though their website will show you some very exciting and dramatic colors — some contrasted with wood side panels. No doubt these will set you back more money, but if appearance is important to you, go for it. Maybe some wood knobs to go along with the side panels? I'm obliged to report that the volume knob set screw loosened up on me several times. And both Tom and I felt there should be a more visible position indicator on both the input and volume knobs. On the back side, the speaker binding posts were inexpensive and did not always hold when tightened with my fingers. (I did a fair amount of component swapping for this review). On a more positive note, the EL84TT is a very transparent amplifier with strong bass and treble and very good focus from top to bottom. It is packed with premium electronic parts, including the well-respected Hammond transformers which they like to point out are also made in Canada.

What The ?!!?!!
I had taken the TT out of the rig and set it on the kitchen counter before beginning the summary of this review. As I walked past it on my way to work the next morning something caught my eye and I noticed that the top of one of the Electro Harmonix EL84 tubes was not as shinny like the seemingly chrome plated tops of the other EL84s. (Carl had given me a mix of one HIT-Ray (Hitachi, NOS from the days of Hitachi tube powered receivers) and one Electro Harmonix tube per channel.) I wondered if... and later that night I found out when I substituted a pair of the well-used Manley EL84 tubes for the Electro Harmonix. The music was different, but it was also largely better, indicating the EH tube with the black top was slowly going bad. Since this was only the second or third time in the past 23 years of using tube gear that this has happened to me, I took it in stride, allowing that such an event comes with the territory. Carl immediately ordered a new set of four Electro Harmonix tubes for me so I could try the combination with the HIT-Ray again, and compare it with a quartet of EH tubes. Had this been my personal amp, I probably would have just ordered a single new EH tube since the amp has an auto-bias circuit. I called a Time Out and waited for the tubes to arrive.

With The New Tubes...
No reviewer that I know of likes to publish a negative review and I was not comfortable with the fact that my experience with the TT was slowly going downhill. You can imagine my relief when I popped the set of four new Electro Harmonix tubes in and fired up the TT. After half a dozen hours or so it evoked my initial enthusiasm once again and continued to improve as I re-traced the music I had previously heard. But something was still not quite right. The upper reaches were still troubling me. As I mulled the situation over at work I wondered if I had mis-oriented the Synergistic Research footers when I reinstalled the TT. That night I switched the hemispherical cones from one pointing up/two-down, to two-up/one-down. Hooray, the focus locked in to a level where it surpassed my reference rig once again. In fact, the tonal coloration was very close as well, though the tonal balance was still tilted slightly upward in the treble.

Not satisfied just to be back into positive territory with the quartet of Electro Harmonix EL84, I re-inserted the HIT-Ray tubes in the first and fourth sockets to learn just what the NOS tubes added to the mix. Of course switching tubes does not allow for instant comparison as there is warm-up time involved, but after a ten minute wait and over the twenty minutes of listening to my familiar compilation CD the benefits of the blended tubes emerged. Stronger bass, more tonal coloration, more three-dimensionality, more dynamics — both micro and macro, the depth of the soundstage shortened up a bit and the soundstage was brought a bit further forward. Or was this the result of the music playing slightly louder? Whatever. The toes dangling off my other knee were once again in active sympathy with the music. And that is an important and often under-rated economic indicator. It puts the EL84TT into serious "Buy Me" territory.

Summary
As with any low-powered amplifier, it is very important to take heed of your speakers, the size of your room, the type of music you listen to, and your preferred listening level. In the context of very efficient speakers in the 99dB range such as the Zu Union speakers used here, the 6 wpc EL84TT comes across as a true muscle amp with deep, tight bass and an extended treble to go along with a multitude of SET-like musical qualities that are not quite world class, but close enough given the reasonable asking price. With the Mundorf capacitors that come standard there is a prominent treble that may or may not be optimal with your chosen speaker. But there is an option to go with Jensen caps that can tame the treble and add weight to the bass and midrange. There are also some minor annoyances with the knobs and binding posts, but these can be upgraded. Then there is the issue with the aesthetics. The TT is like a rather plain girl at a singles dance — no tattoos, no fancy make-up. But man, does she know how to dance! Dress her up with wood side panels and a fancy paint job if you must — she's worthy of the extra expenditure — but take her home and set her up in a proper rig and she will rock your cradle. She may not take home the grand prize on Dancing With The Stars but she won't embarrass a pro on the dance floor. The EL84TT is a real contender at a real world price. In another few years the young dudes at Triode Lab will be running with the big names and you will be paying a lot more for the experience they pick up along the way. Plan A: Ask her to dance now!

Specifications
Type: Integrated vacuum tube stereo amplifier
Output: 6 watts per channel @ 8 Ohms
Output: Class A, autobias
Inputs: Two line level via RCA jacks
Speaker outputs: 4 and 8 Ohm, 16 Ohm available
Tubes: Four EL84 / 7189 / 6BQ5 (power)
Two 12AX7 / ECC83 (line stage)
One GZ34/5AR4/GZ32/5V4/GZ30/5Z4 (rectifier)
Total Harmonic Distortion: Less than 1% at THD+N
Hum & Noise (A-Weight): 88 dB or better at rated power
Price: $2395 CAD

Company Information
Triode Labs
Toronto, Ontario, Canada
E-mail: Email@TriodeLab.com
Website: www.TriodeLab.com