Green thinking has kept automobiles out of my garage and garbage disposals out of my sink. It has forced me to master toilet paper origami. So when I say that my anus doesn’t generally pucker up when I hear about a new, hydro-sucking headphone amp, remember that I get by on two squares a day.

The flip side of all of that is simple economics. Headphone amps can cost a pretty penny. But after literally saving thousands of dollars on toilet paper since I was fifteen, and because the only tyres I buy new are for my Marinoni, I’ve begun to look more closely at investing in a mains-sucking amp for those carbon-footprint-be-damned days. Today’s subject, the rather top-flight Beyerdynamic T1/T5 and Otomatsu BDR-HPA02 combo from Jaben Japan, has piqued my interest because:

- It is economical.
- It sounds damn good.
- It comes with a Centrance DACport USB DAC.
- No toilet paper required.

Think I'm shitting you? Read on.

Spec:

Frequency response: 5Hz -80kHz
Distortion: THD+N 0.0046％
Maximum output power: 1500mW x2 @45Ω / high gain
Headphone range: 16Ω - 600Ω High/Low ゲイン
Power: AC100V 50-60Hz
Size: W230mm x D180mm x H80mm

The above spec list was taken shamelessly from Sasaki san’s amazing Music TO GO! blog.

Otomatsu BDR-HPA02 & Beyer T1/T5P: 248.000¥ (2.480,00 $US)

International users: refer to Jaben’s English website for details on how to purchase the combo for your country.

ohmage: haptics

The BDR-HPA02 is a simple machine. The front bristles with the bare minimum of audiophile flare: an aluminium volume pot, a couple of lockable Neutrik outputs, and a plastic power switch. The outputs come in the following flavours: 4-pin XLR, and 6,3mm stereo phono. The low-profile power switch feels great. Sometimes I fiddle that sucker on and off just for the pleasure of it. (My nipples explode with delight!) On the back, an ATX socket sits abaft the mains socket, a gain switch, and a single L/R RCA input sits abaft the volume pot. With the exception of the gain switch, ergonomically speaking, this amp is sound. It isn't, however, pretty.

ohmage: kitsch

There is nothing necessarily pretty about Beyerdynamic nor Aurora Sound. Evidence: heat sink styling, matte finish, camp stove volume pot. If anything, post steam punk minimalism ran amuck. Kitsch totally fled. Even the Beyer upgrade Cryo cable, a weaved tangle of savoir-faire, coils sombrely next to its mates. CMoy amps in gum tins are kitschier than this.

ohmage and porridge: build quality and finish

Locking headphone ports, thick rubber feet, RCA jacks Titanically anchored in an Atlantic of aluminium and steel- these are the marks of a safe. Considering that you can force your way in with a good Allen wrench, the Otomatsu ain’t no vault. But its build quality sets it right in my carping eye.

Beyer headphones are modular tanks. Take them apart, put them back together. A little scratch never looked so good. Destroying them takes a car.

As for amp finish quality...

This Oto - if I may call it that - looks like a garage project. Maybe it is. It is a little rough around the edges. (Indeed, fingering its edges a few times will sharpen your nails.) In comparison to its tasty power switch, the volume pot's mien is pallid. Its undamped, slightly loose action reminds me of a not-yet CLA’d Nikkor 28/2,8 Ai/S lens. It does the job, but it's not the lens you put on when the your camera geek mates come over to fiddle your film.

Onto the T5p and T1 mods:

Jaben’s T1/T5 wiring work is tip top. The mini XLR ports are perfectly capped and anchored into the headphones. The job is done so well, in fact, that I’m buggered as to why they don't licence their work to companies like Beyerdynamic. This can’t be the same Jaben that prints their amps with nonexistent websites, mislabels buttons, and on and on, can it?

Sound

The T1 and T5 have been reviewed ad infinitum. Ergo, this section will focus on the Otomatsu amplifier. Where changes to the stock T1/T5 exist, they will be noted.

Power

Both the T1 and T5 are easy to drive headphones. The BDR-HPA02 spits out enough voltage in low gain to burn the T1s and enough current to fulfil the more stringent requirements of the T5. Its output isn’t quite able to toast low-impedance planar-magnetic headphones but it certainly supplies enough power to get you into your very own Phonaks.

The BDR-HPA02's noise floor is pretty much even with pre-2009 iPods, if not lower. For a desktop amp, that is impressive. You may find that the output of your portable player or amp is even noisier. My Walkmans certainly are. Many portable amps, like ALO Audio's excellent Rx series, also output a noisier background.

For the record, both Woo Audio's WA7 Fireflies and Antelope Audio's Zodiac Silver have lower noise floors.

I can detect the barest hint of background noise via Audio Technica's ES10. That effect is compounded through Sleek Audio's CT7 / SA7. But there isn't a hint of noise with any proper headphone.

At full volume and low gain, the BDR-HPA02 kept clean signals at the following decibel values via:

- Audio Technica ES10: BDR fed from 2V line out: 86-95dB with peaks over 100dB
- Beyerdynamic DT880/600: BDR fed from 2V line out: 79-90db with peaks over 98dB
- Hifiman HE-500: BDR fed from 2V line out: 79-90dB with peaks over 97dB
- Beyerdynamic T1: BDR fed from 2V line out: 87-95 with peaks over 98dB

The BDR-HPA02 kept clean signals at the following volume settings and decibel values via:

- Grado PS500: from 2V line out: 86-93dB with peaks over 96dB @85% volume
- Beyerdynamic T5P: from 2V line out: 82-92dB with peaks of 97dB @80% volume

The above merely illustrates that the BDR-HPA02 has power.

Beyer 600Ω DT800: set the volume pot to 50% for comfortable listening levels of ~75-80dB.
Beyer 300Ω T1: set the volume pot to 35% for comfortable listening levels of ~75-80dB.

ohmage +1

Balance

The BDR-HA02 is a neutral-sounding amplifier. The stereo image is wide, especially when driving low current headphones like the T1 and DT880/250/600. It also favours no frequency band. It isn’t too wide. It isn’t too cramped. The most apt (and ridiculous) word I can think of to describe this amp’s soundstage ‘endless’.

But even Kraftwerk must quit sometime.

The DT880 and T1 are one thing; a portable headphone like the ES10, or a low Ω home phone like the ES500, is something completely other. When driving low Ω loads, the HPA02‘s stereo image audibly compresses. Mids step forward a little, high and low stereo detail tapers off. But I’m not about to bag that. The mixing, or relaxing of stringent channel separation can be a good thing if only because it is closer to what your ears naturally hear. It also helps that even under stress, the HPA02 doesn’t botch things.

Both the wide stereo separation, which is present under low current loads, and the more compressed stage care of high current loads, sound great.

ohmage +1

Tracking

How about this question: can an amp that was designed to push enough voltage into a pair of 300Ω cans maintain requisite left/right balance normal listening levels?

Yes. With normal to high-impedance headphones, balance is 100% perfect.

How about IEMs?

Even when fed by 2-3V line level outputs, the BDR-HPA02 is able to sustain perfectly balanced signals at modest volume levels. Because noise levels are rather low, you can even enjoy the odd couple. True, your IEMs will force reproduction errors from the HPA02, but that’s never stopped eager audiophiles before.

ohmage +1

Bass vs. Mids

Both the HPA02‘s single ended and balanced outputs spit flat signals. Grip, control, and wide spatial mapping are pillars upon which the HPA02’s output builds itself. Under the yoke of normal loads, bass never intrudes into the mids. Even when lower impedance headphones are plugged in, bass relinquishes control in only the minutest of steps. Oddly, upper bass and lusty mids get the nod under these circumstances.

Yay?

I’ll say. No matter the headphone, the HPA02 plays smooth. It errs on the side of liquid rather than grain. I think it will have its fans.

ohmage +1

Bass vs. Highs

Again, when driving high-impedance loads, both bass and highs step forward on even footing. Stereo width is enormous. Detail in all frequencies is top notch. Only when low Ω headphones and earphones are plugged in does do audible artefacts creep in. But at no time does this amp sound bad.

ohmage +1

Vs. Low-Impedance

Output artefacting is gone by about 30 Ω, but in order to achieve peak performance, headphones with a minimum of 50 Ω input impedance are required.

porridge +1

Vs. High-Impedance

This amp is home with semi-high to high ohm headphones. It has plenty of voltage at low gain for all but the skankiest of wannabe-speaker headphones. It is limited only by current, and that, only when low Ω headphones are connected. Given the right headphones, hallelujah!

ohmage +1

ohmage: Balanced vs. single-ended

Both outputs appear to cover similar voltages. Both supply adequate channel balance. The killer point of this balanced system is that the tame little T5, and the somewhat powermongering T1 change hats a little. The first time I heard the Jaben balanced T5 I just about ate my headgear. Bass, closer to the DT880/32, wider stage. Control is similar. But that bass. Oh that bass.

The T1 doesn’t get any more liquid, it just opens wider. Even my wife liked/loved it. For a time, she wouldn’t let me take it back. I passed by the T1s specifically because its midrange tends to dominate my favourite band, the mid-highs. Well, this T1 (at least with this amp) is a perfect beast.

ohmage +1

Today I powered through three sheets of Bounty and drank half a bottle of vodka. It’s one of those ‘be-damned days. It’s been a glorious couple of months with the BDR-HPA02 / Beyer system. Jaben have a good thing to sell you. You have a good couple of things to think about.

Namely: if you have a system already, is it worth it to upgrade? I can’t say ‘yes’ here unless you are a collector. What about if you are getting into headphones, or are making the big step up to desktop audio? Absolutely. Newbies: don’t waste time and money on cheap, throwaway upgrades that you will upgrade again and again. Go to the limits of what you can reasonably afford and don’t look back. Don’t hamstring your savings, but invest for the long term. This HPA system is great. The inclusion of a DACport means that you can listen to your favourites from iTunes. Concurrent single-ended and balanced output allows you to compare and contrast the two. A package deal lessens shipping costs and obviates sea-saw decisions.

To top it all off, Jaben has stepped up. The craftsmanship they’ve shown in their cables and connection hardware is impeccable- I ain’t shittin’ ya.

ohmage: 10

porridge: 2