lorriman
100+ Head-Fier
- Joined
- Feb 22, 2011
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I've had something of a surprise on purchasing the twin of the HD681, that being the HD681F, and I think it requires its own review.
To introduce the HD681/HD681F: these are supposed giant-killers at absurdly low prices. They are cheaply made but yet seem sturdy enough. You can read other reviews for listening impressions. I'm very pleased with them, though they don't give me any of that tangible texture that I find adds another layer of pleasure as my modded Fostex T50rp Orthos.
I've used a dynamically adjustable sine wave tone generator, Sinegen. My source/amp is the O2/ODAC for the sake of neutrality.
The original HD681 is a great, flattish (over the frequency spectrum, that is) headphone but with a couple of 8db treble spikes at 8000Hz and 12000 Hz as well as an overall treble lift of about 10dbs, which comes to something of a super-hot treble. Consequently, some clever people have produced 'filter' mods using some simple electronics that reduces the treble. there is an alternative to that which I'll get to soon. It also has fairly strong bass, sometimes too strong. Indeed, to call it flat would appear to be somewhat off. However, it's true that the midrange is fairly flat. That flatness contributes to detail, since big swings in volume at different frequencies will mean that you won't be hearing all the music. (The only headphones I have that are absolutely as flat as a pancake are my Etyomtics HF2, which I purchased partly so that I would have a flat benchmark, and also for isolation and the 2 year warranty.)
The HD681F is meant to be a flatter version of the HD681. However, it still has the overall treble lift while losing the strong bass to be about as anaemic as my etymotics. This may seem like bad news but wait a second.....
The HD681F may have the treble lift of the HD681 but it doesn't have the two treble spikes, and...... what I've also found is that the HD681F responds without noticeable distortion to a big bass boost.
This is significant for me because to make the original HD681 give me my hifi experience I have to use a parametric equalizer to take out the treble spikes (on top of reducing treble overall with a filter mod or some other method). This means that I don't use them to listen to spotify or We7 or Deezer or Grooveshark since there is no way to parametrically equalise the audio system-wide on Windows. I'm forced to use my etymotics which I would rather reserve for travel and benchmarking. I only use the HD681 for movies and with my rockboxed (and parametrically equalized) Clip+.
As it happens, Win Vista+ has a driver level support for boosting bass. And unlike the equalizer of Windows Media player (or the ipod), it's high quality and does not distort. Setting the bass boost to 12db at 50Hz while adding in a filter mod (more on that in a moment) and I have myself my hifi experience without the need of a parametric equaliser (UK spelling for the sake of searching). There is still a 3db spike at about 5000Hz which is probably ear canal resonance, but a mere 3db is acceptable.
This is a major win for me. I can also now listen with my friends/GF using my other HD681F.
The other win is that it really isn't necessary to fix up the HD681s (original or F) with an electronic filter to reduce that overall treble. Using the same principle as the filters used on Phonaks and Etymotics, you can simply add folded up toilet-paper to reduce that treble. I've found that 3 layers of double-ply toilet paper does it (I fold in half twice and then tear off one of the four 'quarters' to leave me with three layers). This matches the treble on my etymotics which some find to be too much (a PL30 with the same amount of treble requires a shocking 17db treble increase, to give some perspective). Here it is in the middle of fitting the toilet paper:
Admittedly a 12db bass boost is possibly going to be giving some harmonic distortion further up the frequency range, but so far I can't hear it. Listening to a 50Hz sinewave at high volume and I can't hear anything extra, whereas surprisingly I can hear extra (very little though) with the same on my etymotics even though the etymotics measurements suggest super-low distortion (which should also mean super good for equalizing or bass boosting, which is in fact how I listen to them on my clip+). That Windows driver bass boost happens to double as a bass cut-off to protect speakers/amps from being accidentally over-driven for example from poor mastering (or vinyl wow and flutter). this means that you are losing bass below 50Hz. The Superluxes don't have much bass down there any way so I see this as an acceptable compromise.
As a tip: In fitting the toilet paper I've noticed that the HD681F is missing the triangular piece of carbboard with "Do not remove" written on it, that covers part of the driver on the original HD681. Perhaps that's the cause of the treble spikes. I find it easiest to put back the pads by flipping back the the perimeter plastic (that holds them in place on the phones) before attempting to place them.
To introduce the HD681/HD681F: these are supposed giant-killers at absurdly low prices. They are cheaply made but yet seem sturdy enough. You can read other reviews for listening impressions. I'm very pleased with them, though they don't give me any of that tangible texture that I find adds another layer of pleasure as my modded Fostex T50rp Orthos.
I've used a dynamically adjustable sine wave tone generator, Sinegen. My source/amp is the O2/ODAC for the sake of neutrality.
The original HD681 is a great, flattish (over the frequency spectrum, that is) headphone but with a couple of 8db treble spikes at 8000Hz and 12000 Hz as well as an overall treble lift of about 10dbs, which comes to something of a super-hot treble. Consequently, some clever people have produced 'filter' mods using some simple electronics that reduces the treble. there is an alternative to that which I'll get to soon. It also has fairly strong bass, sometimes too strong. Indeed, to call it flat would appear to be somewhat off. However, it's true that the midrange is fairly flat. That flatness contributes to detail, since big swings in volume at different frequencies will mean that you won't be hearing all the music. (The only headphones I have that are absolutely as flat as a pancake are my Etyomtics HF2, which I purchased partly so that I would have a flat benchmark, and also for isolation and the 2 year warranty.)
The HD681F is meant to be a flatter version of the HD681. However, it still has the overall treble lift while losing the strong bass to be about as anaemic as my etymotics. This may seem like bad news but wait a second.....
The HD681F may have the treble lift of the HD681 but it doesn't have the two treble spikes, and...... what I've also found is that the HD681F responds without noticeable distortion to a big bass boost.
This is significant for me because to make the original HD681 give me my hifi experience I have to use a parametric equalizer to take out the treble spikes (on top of reducing treble overall with a filter mod or some other method). This means that I don't use them to listen to spotify or We7 or Deezer or Grooveshark since there is no way to parametrically equalise the audio system-wide on Windows. I'm forced to use my etymotics which I would rather reserve for travel and benchmarking. I only use the HD681 for movies and with my rockboxed (and parametrically equalized) Clip+.
As it happens, Win Vista+ has a driver level support for boosting bass. And unlike the equalizer of Windows Media player (or the ipod), it's high quality and does not distort. Setting the bass boost to 12db at 50Hz while adding in a filter mod (more on that in a moment) and I have myself my hifi experience without the need of a parametric equaliser (UK spelling for the sake of searching). There is still a 3db spike at about 5000Hz which is probably ear canal resonance, but a mere 3db is acceptable.
This is a major win for me. I can also now listen with my friends/GF using my other HD681F.
The other win is that it really isn't necessary to fix up the HD681s (original or F) with an electronic filter to reduce that overall treble. Using the same principle as the filters used on Phonaks and Etymotics, you can simply add folded up toilet-paper to reduce that treble. I've found that 3 layers of double-ply toilet paper does it (I fold in half twice and then tear off one of the four 'quarters' to leave me with three layers). This matches the treble on my etymotics which some find to be too much (a PL30 with the same amount of treble requires a shocking 17db treble increase, to give some perspective). Here it is in the middle of fitting the toilet paper:
Admittedly a 12db bass boost is possibly going to be giving some harmonic distortion further up the frequency range, but so far I can't hear it. Listening to a 50Hz sinewave at high volume and I can't hear anything extra, whereas surprisingly I can hear extra (very little though) with the same on my etymotics even though the etymotics measurements suggest super-low distortion (which should also mean super good for equalizing or bass boosting, which is in fact how I listen to them on my clip+). That Windows driver bass boost happens to double as a bass cut-off to protect speakers/amps from being accidentally over-driven for example from poor mastering (or vinyl wow and flutter). this means that you are losing bass below 50Hz. The Superluxes don't have much bass down there any way so I see this as an acceptable compromise.
As a tip: In fitting the toilet paper I've noticed that the HD681F is missing the triangular piece of carbboard with "Do not remove" written on it, that covers part of the driver on the original HD681. Perhaps that's the cause of the treble spikes. I find it easiest to put back the pads by flipping back the the perimeter plastic (that holds them in place on the phones) before attempting to place them.
