January 2018

Line Magnetic 218ia Vacuum Tube Stereo Integrated Amplifier Review
A single-ended triode integrated amplifier for everyone!
Review By Paul L. Schumann

  Back in the 1990s, there was an explosion of interest in single-ended triode (SET) amplification. This was spearheaded by two great Japanese designers, Hiroyasu Kondo of Audio Note and Nobu Shishido of WAVAC. Both men designed and built stunning SET amplifiers that were just as much works of art as electronic components. We're talking hand-wound silver-wire transformers and custom-made coupling caps. While they were indeed quite wonderful, they were also on the pricey side. You could still pick up a soldering iron and if were brave enough, make one of your own. Audio Note and Bottlehead still sell reasonably-priced kits. But what if the smell of fresh solder makes you queasy? What are you to do?

I first became aware of Line Magnetic a few years ago when I noticed on line that a new audio salon here in Austin started carrying their equipment. Their prices seemed right. I wanted to drop by and listen. It was always on my "to do" list. Alas, I simply never got around to it. Fast forward to this fall when I asked Ze'ev Schlik of PureAudioProject to review his open baffle speakers, which an SET amplifier would be a good match for his Trio15 Horns (that I reviewed here). Ze'ev mentioned he used Line Magnetic while he was showing his line of loudspeakers within China. Soon I was communicating with Jonathan Halpern of Tone Imports. There were two amps available. One with 300B tubes and one with 211 tubes. Since Enjoy the Music.com had already reviewed a 300B amp from Line Magnetic LINK LINK HERE, I went with the 211. A couple of e-mails later, and the 218ia vacuum tube stereo integrated amplifier was on its way.

The Behemoth Arrives
There's an old adage that starts "Be careful what you ask for...". I've looked at photos of 211 amps, but nothing prepares you for encountering one person. One day I came home to discover a good-sized box affixed to a plywood base at my doorstep. I went to pick it up, but as I started to lift, I had the sudden fear of something internal rupturing. I had my son come and help me bring it in. Later on that evening I was able to switch out the 218ia with my regular JoLida. I thought the JoLida was heavy; Line Magnetic's 218ia is heavy. It's 77.6 pounds heavy! So there was a feeling of accomplishment when I did get set it up in my stereo cabinet. Later on I discovered that the 218ia is the baby of the Line Magnetic series of 211 amps. Yikes!

Once ensconced in its lair, I did an inspection. Of course the first thing that attracts your eye is those 211 tubes. The Shrek quip "Must be compensating for something" comes to mind. The 211, and its sibling the 845, represent the last gasp of triode amplification before tetrodes and pentodes took over. The 211s use tungsten elements that shine bright like an incandescent bulb. With 1000V across the plates, they are just a tad bit intimidating. The front plate of Line Magnetic's 218ia has a voltage meter for biasing, a volume control, a source selector switch, and a LED to indicate mute. The power switch is on the left side. In back are taps for 4, 8 and 16 Ohms and four inputs.

On the top are recessed screws for tube biasing and hum pots, and toggle switches for selecting the tube you a biasing. The 218ia comes with a solid remote control for adjusting the volume and engaging the mute. The 218ia did come shipped with its tube cage to help protect the tubes. I decided to leave it off for the meantime while I was fiddling with the tubes. Besides those giant 211 output tubes, the 218ia has 12AX7s for input tubes and 6L6 driver tubes. You can bias both the 211 tubes the 6L6s using the meters. The whole thing is finished off in a gray hammer tone. This reminded me of some of the instruments my dad used in his lab at IBM in the 1960s.

Now let's talk about the insides. All Line Magnetic amps are point-to-point wired, which is always a big plus. The coupling caps are custom made from Germany. The lack of rectifier tube means power supply is solid state. Since hum pots are included, I assume the filaments use AC current. The power output is rated 12 Watts per channel running pure Class A. This wattage opens up the possibility of pairing the 218ia with a wider variety of speakers than many SET amps.

When you turn on the 218ia, there is a thirty-second delay while the power supply stabilizes. This is indicated by the flashing front-panel light. The first time it kicked on, I noticed that the lights in my abode dimmed. Looking in the manual I saw that the 218is draws 320 Watts! Soon after you turn it on, you feel the heat. These 211 tubes run hot. If you have smaller children, you definitely want to use the cage. Since all of mine have the good sense not to touch very-hot things, I kept it off. I do love the look of tubes.

Before I received the 218ia from Line Magnetic, they burned it in for about 50 hours. Jonathan Halpern told me that the 218ia was a little rough out of the box. So was of little no surprise that when I started listening, it still needed a little break in. I started listening to the 218ia with it hooked up the Trio15 Horns. During initial listening, the 218ia came off a bit on the bright side.

As I listened over the next week, this reduced a little bit, but not completely. I contacted Jonathan for some advice. He told me that this is very sensitive to changes in the input and driver tubes, so I might want to experiment. Luckily, I had the perfect tubes on hand. First, I replaced the stock 12AX7 tubes with the JJ Electronics I purchased for my JoLida amp. Through trial and error, I found these were the best sounding of the modern production tubes. This change smoothed out the highs and eased the great deal of the brightness. I then replaced the stock 6L6 tubes with a pair of the New-Sensor Mullard. This did indeed warm-things-up nicely. Now I was ready to rock and roll!

Cooking With Tubes
What always strikes me when I start listening to an SET amp the directness of presentation it produces. Many amps do well when dealing with a solo instrument, or paired with a voice, yet when more instruments, sings and such get added into the mix things start to fall apart. Whether you are listening to a solo instrument or a whole symphony orchestra, the 218ia keeps it together. Recently my father and I were lucky to go see a performance of Prokofiev's 5th Symphony by the Austin Symphony Orchestra. The key to this piece is complex interplay of the different instruments in the orchestra. When I listened to Karajan's fantastic direction of this work though the 218ia, it reproduced this work with aplomb. In the stirring end to the last movement, Prokofiev interjects a string quartet which is discordant with the rest of the orchestra. This is striking live and for the first time it made sense listening on my system.

A big challenge in any SET amplifier is getting the tonal balance correct. This depends a great deal on the quality of the output transformers and the output tube used. Top to bottom the 218ia does a good job of this. The bass was the best I've ever heard from a SET amp, tight and tuneful. Those giant bass drum blasts in Reference Recording's Pomp and Pipes are always a great system test and the 218ia delivered them with ferocity while retaining the timbre of the drum head. The midrange was a tad on the dry side, lacking some of that 300B magic.

Thom Yorke's vocals on Radiohead's Moon Shaped Pool are as intimate as they get. Here I could have used are little more warmth, but I'm quibbling here. The treble never sounded harsh or etched. Genesis's Wind and Wuthering is loaded with high-frequency information (Phil Collins and his drums!) that it can wear thin about half-way through, but with the 218ia I never felt fatigued listening to the whole album. Overall, the Line Magnetic 218ia gives a pleasing tonal balance that makes you want to enjoy more music right now.

Most the listening time I made with Line Magnetic's 218ia was with the PureAudioProject Trio15 Horns I reviewed in December 2017. When I was done with them, I reconnected my trusty Thiel CS1.5s. On the face value, the Thiels should be an anathema for an SET amp. First, they are low efficiency, rated at only 87dB/W/m. By and large SET amps prefer higher-efficiency speakers. Second, the Thiels have an impedance of 4 Ohms. Low impedance speakers require more current, which is a big stress on SET amps. So how did it sound when I hooked it up. Utterly fantastic! I know that 12 Wpc doesn't sound like much, but it never felt like the 218ia was strained in driving the Thiel small floorstanding speakers. In fact, the Thiels never sounded better!

Thiel's relatively small CS 1.5 floorstanders (33" high) are world-class at doing the whole soundscape thing, so I waited until they were hooked up to make my observations in that area. Line Magnetic's 218ia did a great job of placing full-bodied instruments in the soundscape. A truly great disc to listen for this is Mahler's 8^th Symphony with Philharmonia Orchestra directed by Benjamin Zander [Telarc B00006EXK1]. With the 218ia the Philharmonia Orchestra was spread out before me, slightly forward and to the outside of the speakers and extending straight back. While individual instruments were not always easily located, each section was distinct. The reverb in the hall was rendered nicely, giving warm spacious feel this live recording!

A Tube Amp For All Seasons
What can I say about Line Magnetic's 218ia vacuum tube stereo integrated amplifier that I haven't already said? It is a very well built product that inspires confidence right out of the box. You can adjust its tonal balance easily by switching out the input and driver tubes (read: tube rolling). It sounded great with high-efficiency horns and my low-efficiency Thiel CS 1.5 floorstanding dynamic driver speakers.

It has the bass that rockers crave, yet still has a clear midrange classical and jazz fans will appreciate. It's reasonably priced, yet sports high quality components. That is why I'm calling the Line Magnetic 218ia stereo integrated an amp for all seasons.

Specifications
Type: Integrated vacuum tube stereo amplifier with four source unbalanced RCA inputs
Tube Complement: Two12AX7 input tubes, two 6L6 driver tubes, and two 211 output tubes
Power Output: 12 Watts per channel
Frequency Response: 10Hz to 50kHz（-1.5dB)
THD: 1% (1 kHz)
S/N Ratio: 87dB (A Weight)
Input Sensitivity: 200mV
Dimensions: 380mm x 400mm x 275mm (WxDxH)
Weight: 77.6 pounds
Price $3500

Company Information
Line Magnetic Audio Co. Ltd.
Fourth Floor, Building No.2
Ping Xi Road No.6
Nanping Industry Park
Zhuhai
Guangdong Province, China

Voice: (86) 0756-3911922
Fax: (86) 0756-3911933
Website: www.LM-Audio.com