Actually, the proper name is simply “The Hemp Headphone Limited Edition”, but that would not be very clear as a heading. We want people to know that these are Grado headphones. That name carries its own rather prestigious reputation. Either way, it does make you wonder: how is hemp used in headphones? What does it do? Read on as we try to work that out.
- On ear, open-backed headphones
- Dynamic drivers – size not stated – matched to within 0.05dB
- Nominal impedance: 38 ohms
- Sensitivity: 98dB for 1mW input
- Frequency response: 13 to 28,000 hertz.
- Replaceable foam ear pads
- Fold flat for transport – no case included
- Hand-built by Grado in Brooklyn, New York.
- Hemp and maple body
- Fixed 8-conductor cable terminated by gold-plated 3.5mm plug
- Gold-plated 3.5mm to 6.35mm adaptor included
- Summary: Is it the hemp in the construction that delivers nicely balanced, dynamic headphones? These are for those who prefer on-ear to than over-ear. And they deliver a solid bass, that is actually enhanced when using second-rate headphone amplifiers. Good trick Grado!
- Price: $699
- Available at fine high fidelity retail outlets, and direct from distributor's retail division here.
So, it seems that Grado has been keen to use hemp material in its headphones for quite a while. Grado has long been an advocate of using various kinds of wood as bodies for its headphones and for its premium phono cartridges. Apparently, the opportunity to try out hemp came to Grado, rather than it actively seeking out the material.
The idea of using unusual materials is that their natural physical characteristics shape the sound in a pleasing way.
Hemp is normally used as a fibre. Where a solid application is required, it’s typically mixed in with some kind of binding agent. Grado felt the need to include maple in the construction of the bodies of each side. The result is certainly visually striking. Without A/B checking against an otherwise identical design in plastic and metal, I wouldn’t be prepared to comment on what it might add to the sound.
Now it’s likely that the hemp used in the manufacture of these headphones is industrial hemp, with far lower levels of the stuff that makes the other type of hemp so popular. That hasn’t stopped Grado playing with the association, with the distinctive cannabis leaf silhouetted on the headphones, and an animated photo on its website that has the headphones woozily warping as a smoke wafts in front of them.
The headphones felt light on my head. As you can see from the pictures, the headband is leather covered and the height of the earpieces are adjustable by sliding their metal rods though plastic clamps at the ends of the headband. While comfortable overall, I will confess I’m not a fan of the feel of on-ear headphones, and I found the foam surface just a touch rough on my ears. I feel kind of wimpy writing that. Perhaps I’ve just been spoiled lately with soft velvety finishes on over-ear earcups.
I happened to have an ancient best-of LP on the turntable when I unpacked these headphones. This is entitled Karajan: Festival of Hits from Deutsche Grammophon, a nice sampler I’ve had since I was a kid. I went off it for a while because the 1980s hifi sensibility leant rather too heavily into treble prominence, making a lot of Deutsche Grammophon recordings sound peaky in the treble. Naturally the LP has some surface noise, but the Hemp headphones didn’t particularly emphasise it, nor did they hide it. Liszt’s Hungarian Rhapsody No.2 was delivered with a nice dynamism, and a good, solid bass.
Happily we’re not in the 1980s any more.
The grouped violins in the Act III Prelude to Verdi’s La Traviata were sweet, not steely. That’s always a good sign. The side ended up with a massive choir singing the conclusion of Haydn’s The Creation. The headphones kept things under control, and allowed me to pick out the parts quite easily.
Moving over to digital music, I listened to Genesis’ second album, Trespass, streaming from TIDAL. Tonal balance was excellent, with good mid-bass balance (no deep bass on this album to judge from). The headphones were very revealing. The electronic processing on Peter Gabriel’s voice on “Visions of Angels” was rather obvious, speaking to the transparency of these headphones. The drums – even though this is pre-Collins – were delivered with authority. I’ve heard some commentary to the effect that the drumming doesn’t measure up to what was to come. Perhaps. I like it nonetheless.
On “Maybe” by Janice Joplin, a nice recording from those pre-compression days, the Hemp headphones delivered the drums with no significant dynamic compression, and plenty of detail so that I could hear the individual character of each. The unfortunate deep bass noise that somehow made it into the recording was certainly hinted at, with the 26 hertz fundamental a little recessed. But the bass guitar line was at just the right level, rich and full.
Sticking with the blues, but from half a century later, Harry Styles’ “She” from Fine Line was delivered with a good, strong bass guitar performance, and a rather delicious clarity on all the swirly little ornaments scattered throughout the song.
Now, an interesting thing happened after I checked the impedance of these headphones. With the headphones on a cardboard box acting as a proxy head – this traps air in front of the drivers, changing their acoustical characteristics and therefore their electrical characteristics – the headphones appear to exhibit a continually rising impedance the deeper you go into the bass. It rises, with some bumps, significantly from somewhere below 200 hertz such that by 20 hertz, a headphone amplifier with a high inline resistance will be boosting the bass by around nine decibels.
Here’s the graph showing this (the white line is with the headphones sitting on my desk, but this doesn’t represent real-world performance):
That isn’t the usual pattern. Often headphones exhibit a significant bump in the middle to upper bass, which fades off again into the deeper bass. So I wondered: how would these headphones sound driven by headphone amplifier with a high output impedance? Not theoretically, but actually?
Well, I have a home theatre receiver here with a high output impedance – 470 ohms, more or less – and I have to say that they sounded really, really nice. Especially with music with a fulsome bass, such as “Wrapped Around Your Finger” by The Police. I think there is a deeper bass rolloff in these headphones, and it’s nicely counteracted by the boost provided by high-impedance output sources.
So I went back to my iFi ZEN CAN headphone amplifier – which has an output impedance of around half an ohm. And the sound was identical. How could that be? Surely the difference in bass boost would be obvious. What was going on?
Around then I realised that the “XBass” switch on the iFi ZEN CAN headphone amplifier was switched on. As the name suggests, this also boosts bass. Indeed, it is remarkably similar in effect to a high output impedance amplifier driving these headphones. Compare this frequency response graph with the one above.
This bass boost wasn’t always entirely welcome. With some of the rather bass-forward Billie Eilish tracks, the bass was overdone. With those I preferred the iFi ZEN CAN, XBass definitely switched off.
(A full explanation of the significance of high output impedances is here.)
Normally, I’d write that the headphones are not suitable for use with high-output-impedance amplifiers. But since the curve keeps on going up into the deep bass, and the headphones clearly have the capacity to handle the louder deeper bass signal, I think many owners of such sources will actually get a lot of pleasure from these headphones.
So, if you want very nice sounding, on-ear headphones, you ought to check out the Grado Hemp Limited Edition headphones. Especially if you want headphones that look way, way better than most other brands. Find a store than handles them and go listen.
Note: the Grado Hemp headphones are one of the company’s limited editions. That means they won’t be around forever. So if you’re interested, it’s probably not a good idea to wait around until there’s a Version 2.