L-2 Parafeed Headphone Amplifier

In audio, as in most things in life, there are tradeoffs. The tradeoff for the liquid midrange of vacuum tubes has always been bass, speed, and punch. With the L-2, we have eliminated this tradeoff.

Designed for sensitive dynamic headphones, the L-2 matches especially well with high-end headphones like the Sennheiser HD800s, Beyerdynamic T1s, and Grado RS1s. In fact, we think it is about the best amplifier available for the HD800s or the T1s regardless of price. Our unique circuit marries the traditional crystal clarity of tubes with bass that has power, depth, and pace, and extracts nuance and musicality. We do this through a thoroughly modern tube circuit built without feedback.

Headphones are extremely sensitive. This means that a good headphone amplifier needs to be quiet, and the L-2 excels at this. In fact, the L-2 is so quiet that, even with low impedance headphones, you simply cannot tell it is on. There is no noise, no hiss, no buzz, no hum -- nothing, just silence. Additionally, while playing loudly is important, in driving most dynamic headphones, it's the first milliwatt that matters. The L-2 can play plenty loud to hurt your ears, but what you'll notice is that it doesn't have to. The L-2 conveys such depth into the music with such a black background, that all of the subtleties come through even at low volumes.

For the technically minded, the L-2 is a single tube, parafeed, "spud" amplifier for headphones. It uses the 6C45Π, a high-mu, high-transconductance tube for amplification and output power. Further, rather than simply using high end parts, the L-2 redefines what a tube circuit is in a way that was simply not possible in the past. Designed based on the culmination of years of experience, the L-2 uses modern solid state parts to help the tubes perform the best that they can, better than they were historically able to.

L-2 Parafeed Headphone Amplifier Schematic

The L-2 uses cascoded MOSFETs to provide an extremely high load of several mega-Ohms to the plate of the tube. This high impedance load, in addition to operating the tube in its most linear range, also provides more than 100dB of isolation for the audio circuit from the power supply. (For our white paper on the topic, please see our article on Designing a Parafeed Headphone Amplifier.)

The L-2 also uses a novel bi-polar transistor shunt regulator to provide a very low impedance and very linear bias. The tube is then capacitor coupled with high quality V-Cap capacitors to nickel core output transformers custom made for us by Electra-Print audio.

Additionally, the L-2 uses Lundahl mu-metal or Amorphous core input transformers. The transformers serve several functions. First, they act as balanced to single ended converters for those with balanced sources. (The L2 works just as well with a single ended source as with a balanced one.) Second, good quality input transformers (and the Lundahls are the best in the world) reject upwards or 120dBs of common mode noise. This not only results in an extremely quiet amplifier, but it also renders the interconnect used nearly immaterial.

All of this adds up to a very clean, fast, powerful amplifier, with the liquid midrange that only a single ended tube can provide.

The L-2 is sold out. Please contact us for information on our upcoming products.

© 2014 ecp LLC | Last Update: Sunday, 09-Feb-2014 21:34:40 MST