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TubeMagic Canada IAM98 Tube Amplifier Review

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TubeMagic Canada IAM98 AmplifierThe prospect of reviewing something from a new company is exciting for most honest reviewers. We’d rather “discover” something new, than walk a path already cleared. It’s an ego trip, I suppose. Speaking for myself only, I’d rather collaborate with someone who could use a “leg up,” than with someone who is either jaded or full of hubris. When Jean-Pierre Boudreau, the rep for TubeMagic Canada, contacted me to ask if I was interested in hearing something new, I was immediately interested. New is a good thing, just like babies are good. In the beginning, all things are possible.

TubeMagic Canada has been around for a few years, probably just in time for the Great Recession, so the company is still small and relatively unknown. However, looking at the website, you will see some fairly refined-looking products. Nothing outlandish, but how many can afford outlandish these days? There are already enough $100K turntables and speakers, $50K phono stages, $10K cables…. And people wonder what’s wrong with the high-end. Well, if I were interested in audio, flip open my first high-end magazine at the newsstand, and saw that I’d have to spend more for a system than what I spent on a car, a truck and a 1,850 square foot house, I’d decide to pick up an affordable hobby like restoring muscle cars. A ’69 Corvette, or a preamp? Hmmm. I know which one is more fun, and, unlike audio, just about everyone who matters digs muscle cars.

Tried and true

The recipe for the IAM98 is conservative and proven. Being an integrated amp, it will work for most audiophiles with most speakers and in most rooms. It has enough power and enough inputs to fit in the average audiophile’s system. Inputs and binding posts look high quality. The unit is heavy—always a good sign, especially when the face plate isn’t 1-inch thick. The weight appears to be almost all in the places where it counts: transformers and chokes. No audiophile air in the box. Actually, the unit is quite densely packed, and one of my only worries is heat load on the caps. I didn’t have any problems, but I’d recommend not placing the unit in a confined area. There are lots of tubes, resistors and transformers, all of which produce heat. Unless the manufacturer recommends against it, I’d also recommend leaving the top cover off. Tube and component life will be extended. It reminds me of some of the really great tube integrateds of times past: lots of parts and lots of heat. None of this should be taken as a negative. All tube gear produces heat and that heat always causes stress on the associated passive parts. For some, top-opened amps with red hot tubes aren’t an option because of kids or pets. With the IAM98, you have the option to run it as a hard-top or convertible.

Keeping things simple and conservative, the IAM98 appears to sport a choke loaded power supply, which is almost always a guarantee for success. You have to be particularly inept to screw up a choke loaded power supply. In my opinion, chokes are a sure sign that the builder is serious. On the other hand, chokes are heavy and expensive in comparison to solid-state regulators. So, the IAM98: a conservative design of a liberal build budget. It’s like the saying with muscle cars: there’s no substitute for cubic inches…and before you say something about superchargers or turbos, remember that forced induction is a way of making a small engine swallow the same amount of air and fuel as a big engine. Chokes ‘r good. So are tubes, and the name isn’t TransistorMagic, is it? The output sounds like an ultralinear circuit, based on the amount of power and the sound quality. Output tubes are KT88 and bias is cathode bias; AKA self-bias. The input tube is shared between the two channels, as is a 6DJ8. The next tubes are a 6DJ8 for each channel, which I assume operate as a long-tailed-pair phase splitter, followed by a 6SN7, which I assume is the driver tube for the outputs. Again, it’s tried and true, something that has been adopted with great success by Leak, Eico, etc., all of which are quite collectible, but quite old, and quite out of their warranty period. Quite sensibly, rectification is solid-state. A choke-loaded power supply eliminates the noise produced by solid-state rectifiers. Solid-state rectifiers increase reliability. They also lower the power-supply’s impedance, the cost of ownership, the power transformer ratio, etc..

The volume control is a stepped attenuator with wire-wound resistors, from Dale-Vishay, I think. Wire-wound resistors have lower noise than most metal film resistors, hold up to heat better than any other kind of resistor, thus more reliable and stable. Coupling caps are Jensen copper foil paper-in-oil with silver leads, which are significantly more expensive than any of the boutique polypropylene caps. In my experience, paper-in-oil capacitors offer performance advantages that aren’t explained by numbers on paper. The rest of the IAM98’s body parts are aluminum, and the sides are made from some kind of multi-ply wood, like an LVL (laminated veneer lumber).

There were a couple PCB issues I had, something that can be easily fixed in subsequent production. The board has KT88 and 6L6 written next to the output tube sockets, implying that you can run both a KT88 and a 6L6. That’s not the case. I think the idea is that the board is a universal board since both tubes have the same pin-out, thus can be used with either tube, but not with the same plate voltage and current. Also, a couple through-holes seem a little too close together for the size of the capacitors being used. In the review unit, there were no operational or reliability problems. There isn’t a remote or a balance control. All things considered, the choice of circuit and components are thoughtful.

After I was finished with the review process, I asked Jean-Pierre for specifications. It seems I was right about some things. What is most interesting is that the amp puts out 40 class-A watts per channel, which runs contra of most KT88 amps that run class-AB and closer to 60 watts per channel. It’s interesting that the designer decided to run class A, but keep things ultra-linear as opposed to triode wired. Ultra-linear is a compromise between the power of a beam-tetrode/pentode and the low distortion of a triode, and the IAM98 proved the hypothesis. If I had to guess how much power I was listening to, I would have thought at least 60 watts.

Making magic

Hook-up was as straight forward as is possible. With power, speaker and three inputs, things couldn’t be easier. At first listening, things were slightly veiled and forward. The break-in period was shorter than transistor gear, taking a couple weeks to fill in and relax. After another couple weeks, the sound was still a little flat and forward. I figured tube rolling would tell me if what I was hearing was the amp or the tubes. I went through various 6DJ8 types, including the variants and pin-compatible subs, and 6SN7s. The IAM98 comes with 6922 from Philips ECG, which are affordable and long-lived. I tried various combinations of German E288cc, 6922, NOS surplus military (not Sovtek) 6N1p, Brimar 6BQ7, Siemens E88cc and RCA 6FW8. The 6BQ7 was a step in the wrong direction, creating a glare not unlike a classic midrange horn. The 6N1P was a little dead-sounding, or perhaps too dark. With the Siemens E88cc in the second two tubes and an E288cc in the input position, the sound improved. What was interesting was using RCA 6FW8 which were just as clear as the more expensive E288cc and E88cc, but with a warmer (euphonic?) tonal balance. I did my listening about 50/50 between the 6FW8 and the expensive German tubes. A sub I should have tried was the 6N23P-EB, which is a fantastic sounding tubes. There are hundreds of subs you can try when considering the pin-compatible tubes and the various brands available. My sampling was hardly exhaustive, but showed that a tremendous change in sound can be achieved by subbing for the first three tubes in the amp.

My adventures with the 6SN7 were quite interesting. The review sample included Russian versions. My first sub was Sylvania “chrome dome” types, which were a little better, but not night-and-day. The next tube was the tall-bottle Japanese 6SN7GTB which was similar to the stock tube, being a little thin and bass-shy. The next candidate was the “red base” JAN RCA CRC-5692. These are excellent tubes, with good bass, low distortion and good imaging. A surprisingly good tube was the regular (short-bottle) Japanese black-plate 6SNn7-GTB. They gave up a noticeable amount of deep bass, a couple dB less is my impression, but had similarly good imaging. The tonal balance was warmer, perhaps a little more even-order distortion. Overall, the difference between 6SN7’s was much less than between various 6DJ8 tubes. Admittedly, some of the tubes I subbed for the 6DJ8 had significantly different specifications. I spent most of my time listening to the 5692 and black-plate 6SN7-GTB. The bottom line on the 6SN7 is that most are at least competent sounding. The same cannot be said of a number of the 6DJ8 types (some are awful sounding).

The first output tube substitution I tried was a negative experience. I tried a quad of used MOV KT88 that tested good, but one of the four obviously had an issue and started to glow cherry red. None of my other attempts provided appreciably better sound than the stock Valve Art (Chinese) KT88. This is great news. The stock tubes never hinted at any problems with longevity or quality control. I left the amp on, idling, for many hours, and there was never any indication that the output tubes were getting weak or gassy. The Chinese have a come a long way with their output tubes, while their filamentary triodes were already very good. Still, almost all current production small-signal tubes suck from all that I have heard. Perhaps the weaknesses of power tubes are covered up by the larger signal, where the distortions in small-signal tubes are more noticeable, especially in phono stages. I’m not 100% sure, but I’d advise against spending big money on NOS power tubes. Small signal tubes tend to make a bigger impact on the sound, last longer and are cheaper.

Once I settled on some upgraded tubes, the sound of the TubeMagic was both transparent and large. Depending on my tube choices, the tonal balance could be slightly lush or relatively even-handed. I auditioned the IAM98 with GR Research line-source speakers at an equivalent 97dB efficiency and 4 ohm load impedance, though a complex crossover, cables from Wireworld, Aural Symphonics and Clarity Cable. The phono stage was the Rek-O-Kut budget unit.

The strength of the TubeMagic is the same for most tube integrated amps, but at a higher performance level than any of the previous tube integrateds I’ve used. The sound was both fuller and more open than the Grant Fidelity RITA-340 and the Luxman SQ-38u vacuum tube integrated amps I’ve reviewed. Obviously, it was far superior to any of my classic integrated amps, having much lower distortion, less veiling, more power, better impact and more open highs. The comparison is not quite fair since those classic units, along with the Luxman, had balance and tone controls. Though I rarely felt like I needed tone controls with the IAM98, I could have used a balance control on a few records.

Image width was very good. I repeatedly heard images outside the speakers in conjunction with a solid center image. Depth was good, but it depended on the tube choices. In stock configuration, image depth was average. With E88cc, E288cc and 5692, the depth was very good, though not the equal of state-of-the-art gear, especially great single-ended power amps.

Rhythm and dynamics were excellent. There wasn’t as much “jump” as the best, but it was still good. Its ability to climb a dynamics ladder was proven by the last movement of Shostakovich’s 7th Symphony (Bernstein and Chicago SO). It was able to get louder and louder and maintain composure. When it did run out of power, it compressed rather than audibly clip.

High frequency extension was extremely good. The overtones of strings and cymbals were differentiated and the difference between CD and vinyl was quite obvious. On the other hand, bass depth was only good, not exceptional. Bass softens in the last octave, with some compression at high levels. The amp can deliver more power than the output transformers can handle, which isn’t unusual. The effect is more audible when compared to the highs, which seem to have enough extension to recreate any instrument. I wouldn’t call the TubeMagic bass-shy, but it’s not its strength. Depending on speaker choice, things could improve. The load of the GR Research line sources is more difficult than any of the classic horn designs, and similar to speakers intended for solid-state amps. It’s not a torture test, but it did expose one weakness of the amp.

The above-average clarity and low distortion of the TubeMagic allowed me to hear the differences between individual tracks and different pressings. It did this without sounding sterile or cold. The net result was long listening sessions, low levels of listener fatigue and plenty of information. I found myself revisiting old favorites and trying a greater number of new recordings than usual. That tells me that it’s a good piece.

Closing thoughts

It’s no surprise to hear good sound from Canadian gear, but the refinement of the IAM98 was unexpected. The strengths far outweigh the few weaknesses I heard. If you want information, but prefer a warm tonal balance, the TubeMagic IAM98 delivers. The combination of transparency and forgiving tonal balance is difficult to find and more closely resembles the sound of live music than that of ultra-high-resolution gear. It reminded me of why I started listening to tubes in the first place. With very few reservations, I can recommend an audition of the IAM98.

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