HP 4 headphone Amplifier
as reviewed by Robert H. Levi
Designed and constructed by Tim de Paravicini at E.A.R. in England, this all tube headphone amplifier is simply the hydrogen bomb of headphone amps. Completely ignored by Stereophile and Absolute Sound since its introduction to the states in 2000, its hot demand today defies its lack of reviews and is a word of mouth phenomenon. Clearly out-classing and out-defining all rivals at any price that I have heard in the last 50 years, its staggering fidelity, superb flexibility, and top build quality scream bargain even at its current price of $5250.
Supplied with four select Russian 6SL7 tubes and fully balanced with multiple transformers, ice cold right out of the box, it made my King Rex amplifier, Grado battery amp, and both my Benchmark units sound uninvolving and artificial. Even my Stax and Koss Electrostats sounded less defined and dull compared to the E.A.R. HP 4. Attached to my ModWright Sony 999 and McIntosh Audio Classics Modified MR71 Tuner, my E.A.R. 834L Linestage was connected to the HP 4 with all tip top Kubala-Sosna Elation and Emotion cables and power cords. My headphones used for listening include the astounding Grado PS1000 and the extraordinary Ultrasone Edition 8. Also used were the Sennheiser 600 and 650 cans and the venerable Grado RS 1s.
I hosted a parade of audiophiles with their favorite cans over a one month period to check out the E.A.R. All of them suggested that the HP 4 was truly the best. All were stunned by the intense realism and neutrality of the HP 4. The bass, mids, highs, definition, and dynamics were unequaled in their minds and mine. The HP 4 is a landmark product and sets the bar for all other headphone amps at what may be unattainable for a lesser designer.
Here's what E.A.R. says about the HP 4. "Tim de Paravicini has long had a worldwide reputation for valve preamplifiers and power amplifiers. Now he has applied his expertise to produce what is arguably the world's finest headphone amplifier aimed at the highest quality dynamic headphones.
The HP4 uses 6SL7 valves, properly matched to the load through de Paravicini's renowned transformers, to deliver nearly 1W of high quality, low distortion power into high or low impedance headphones. The output circuit configuration uses de Paravicini's 'Enhanced Triode Mode', as employed in the highly successful V20 and 859 integrated amplifiers, while the input is also transformer coupled, giving the flexibility to accept balanced or unbalanced signals from the preamplifier.
For the greatest user convenience the HP4 has its own volume control, while input signals can be independently switched through to the power amplifier for headphone and/or loudspeaker listening. As with all E.A.R. products, reliability is paramount and valve life is in excess of 10,000 hours."
With four phone jack inputs for two low z and two high z cans, the flexibility is amazing. You can even insert the unit between a preamp and amp and switch in and out the main loudspeakers. I used both the balanced and single ended inputs and outputs and found nothing to criticize. At nearly 20 pounds and built on the same chassis as the 834L linestage, we are talking robust for sure.
Tube Rolling: THE Sport of Audiophile Kings!
I easily popped the bonnet and pulled the Russian tubes. I replaced them with a quartet of Adzam [Dutch Amperex] tubes from Kevin Deal at Upscale Audio in Upland, CA. Whoa! The increase in air and ambience, the drive and pacing, all became enormous. Not as neutral as the Russians, but what a thrill ride. I think a bit fatiguing, too. Next, I plugged in a set of Sylvania Gold tubes from Kevin. Ah, these are nice. Their warm, rich power was exciting and revealing. Again, not as neutral or even natured, but oh so fascinating and fun. You've got to love tube rolling!
Then came the G.E.s also stocked by Upscale. Like the three little pigs, these were just right. With all the evenness and neutrality of the supplied tubes they added a big increase in definition and realism. These were the ticket to ride with this design. I even tried a cocktail of tubes, but returned to the G.E.s. I think RCAs may sound equally good. What a killer combination! Thank you Kevin Deal and Upscale Audio for the loaners!
By the way, the 6SL7 is a twin triode tube developed in 1942 by G.E. They have the most experience on the planet with this tube type. Also, in this circuit, all tubes are used all the time. You can create a tube cocktail by replacing just one or more tubes with different brands to modify the sound quality to suit your tastes or cans.
However, I will say this. If you choose to live with the supplied tubes, no worries. Their performance is quite grand and a fine choice by E.A.R.
After 10 years in virtual obscurity, the E.A.R. HP 4 Headphone Amp is now a big-time phenomenon. With conventional headphones approaching the $2000 price point, this high-end E.A.R. masterpiece makes real sense. A sonic leap over the most extravagant competition known to me or my audiophile friends and associates, the E.A.R. is the best of the best for maxing your cans with any source. The HP 4 is a recording engineer's must own. It is the first headphone amp to embarrass and out-perform electrostatic phones, with top notch conventional cans sounding better. The HP 4 cannot be ignored or surpassed. To hear the E.A.R. HP 4 is to own it. I bought the review sample. It is the state of the art! Robert H. Levi
E.A.R. HP 4 Headphone Amplifier