LM-34IA Integrated Amplifier
David Hafler, with the help of Bob Tucker, designed the Dynaco ST-70 in 1959 to reduce distortion and improve audio quality with four EL34 output tubes. At the time, solid-state amps were dominating the market and the ST-70 was available at a surprisingly affordable price. More than 350,000 ST-70 amplifiers had been sold when production finally ceased, making the ST 70 the most popular tube power amplifier ever made.
The Line Magnetic is a well-built, modern interpretation of one of the most influential amplifiers of all time; the Dynaco Stereo 70. Its design was based on EL34 vacuum tubes.
Dynaco Stereo 70 background
"If we want to talk about influence—and a long-lasting one—we’d start with this seventy-watt stereo unit, which, during its 20 year (or so) life span was studied and copied by many young designers. It was a diving board for some, like William Z. Johnson (of Audio Research) whose earliest tubed units were built around the Dynaco chassis and parts (highly modified, of course). The 70, and its descendants the Mk2 and 3 versions—came along just as stereo sound was being born. Fortuitously, its compact size, full-bodied sound (throughout most of the frequency range) put it in direct competition with the much more expensive Marantz and McIntosh units."
Read the review in Absolute Sound here
The Line Magnetic LM-431A is the closest thing to the ST70 and gets you into the beloved EL34.
EL34 is a widely used vacuum tube model for guitar amps and home stereo amplifiers.
Why EL34 and not other tubes? – EL34 has unmatched musicality when compared with KT88 tubes, which offer more bass but lack of the sweetness of an EL34 sound. EL34 tubes can also take high voltage up to maximum 800V to deliver high power output. In some tube amp design, EL34 can deliver up to 50 watts of output per channel with its much desired musicality. This cannot be reached by 300B tubes so EL34 has its own sound niche and has been pursued by worldwide audiophiles and musicians for decades.
Check out our Vintage system here
The path to tube magic
1) Start by designing around a Pentode vacuum tube such as the EL34.
2) Employ point-to-point wiring.
3) Use the best transformers. Line Magnetic uses Japanese made, specially designed EI transformers for power supply and two EI output transformers with wide bandwidth
4) Use the best components - Line Magnetic uses an ALPS volume control and Realcap capacitors
5) Give users the option of tube rolling. A two-position tube selector switch on the unit's top plate lets you select your tube of choice: KT88, KT66, KT70, KT90, KT100, or 6550s.
User bias control has been used for bias adjustment and one meter has been added to the top plate to allow you to monitor bias with ease with a true ampere meter.
Reviews
"This is my power tube of choice" Hifi News
The EL34 was widely used in higher-powered audio amplifiers of the 1960s and 1970s, such as the popular Dynaco Stereo 70 and the Leak TL25 (mono) and Stereo 60. The EL34 is found in many British guitar amps and is associated with the "British tone" (Vox, Marshall) - quoted from Wiki
"The amplifier revealed a few pleasing tricks up its sleeve, including that delicious upper mid-band and treble insight that EL34s often do so well. This is my power tube of choice and the LM-34IA reminded me instantly why I'm a fan. Vocals of all types were reproduced beautifully and had an accomplished sense of clarity and space around them" read the review in HiFi News
" What came as an unexpected surprise was the attention to detail and sheer quality that the manufacturer conjured up here. The execution being noticeably better than some equipment that I have previously purchased, at a price point much, much higher. In fact, even better than that of my experiences with equipment coming from manufacturers who are considered to be (or irrefutably are) at the top of heap."
"It is because of components like the LM-34IA, boasting attractive cosmetics, excellent sonic performance, solid construction and flexibility of features, that the budding audio enthusiast can confidently and soundly invest their “hard earned" while being safe in the knowledge they are in possession of a quality, well-built product. This is a responsive, well-engineered integrated amplifier."
read the review here
Specifications
- Class AB amplifier - 2x40W RMS
- THD: 1% (1kHz)
- Signal/Noise ratio: 88dB (Weighted A)
- Frequency response (-1.5dB): 10 - 50.000 Hz
- Sensitivity: 200 mV (Mode intégré)
- Input Impedance: 100kΩ
- TUBES
Input stage: 1x 12AX7 - 2x 12AU7
Power stage: 4x EL34 - Load impedance for HP to connect: 4/8Ω
- Inputs
- 3x Line inputs RCA (pair)
- 1x Pre-in input
- 2x Screw speaker terminals compatible with banana plugs
- Included; Metal and removable tube guard cage
- Infrared Remote control
- Finish: Black
- Warranty Two years parts & labor / 90 days on tubes. The warranty covers the cost of repair and return shipping.
