Greg Smith

Past columns from The Entry Level are also available.

April 1997

Headphone products from HeadRoom and Grado

I've never really liked headphones. Sure, I own a few pair of them, and use them occasionally. But there have always been problems that kept me from getting really serious about headphone reproduction. Foremost in that list is that fact that I've always found them irritating for long-term listening. One of the reasons I originally started getting involved with more upscale audio equipment is that I'm cursed with an extreme sensitivity to certain types of distortion. Put me in a room with a clipping amplifier, and I go crazy. Ditto for cone breakup. You'd think that headphones would be ideal for me, then, because there is so much less power or cone movement required with the driver sitting right next to my ears. Wrong! Fact is, most headphones that sound good require quite a bit more power than your typical headphone jack is capable of producing cleanly. And since your average headphone is considerably more revealing than similarly priced speakers, you don't have to spend much to get headphones that highlight all the flaws of the equipment you have them hooked up to. There are other oddities to contend with as well. Headphones give you a somewhat bizarre mental image of the sounds you are listening to, with sounds bunched up in the left, center, and right of your head.

Apparently I wasn't the only person dissatisfied with the state of headphone listening. HeadRoom has made quite a name for itself over the last few years by making headphone products that address all the problems I've noticed, and selling them for reasonable prices. This month we'll take a look at their least expensive headphone amplifier, the Little HeadRoom. Along the way, we'll also check out some of the popular budget headphones from Grado.

Feeling cross

When you listen to a normal stereo setup, you have two speakers reproducing sound that's picked up by your two ears. Speakers don't just beam the sound directly into each ear. Your left ear may be closer and aligned better with the left speaker, but that left ear still hears plenty of sound from the right speaker, too; this sound from the opposite channels is often referred to as a cross-feed. Sounds from the speaker that is further away take slightly longer to reach your ear. Based on that, along with some other auditory clues, your brain attempts to place sounds in space relative to where your head is.

Cross-channel sound accounts for some of what we call imaging. The brain processing that sorts everything out is very complicated, and a variety of techniques have been developed to try and fool it into better recreating the original musical scene. You could get a Carver component with their Sonic Holography circuit, which tries to cancel some of the cross-feed and give a more believable image. You could buy certain speakers from companies like Polk, who have introduced models with extra drivers wired to do the same. At the more extreme end of the market, there are techniques that really do freaky stuff to fool your ears. Music encoded with Q-Sound can convince you that sounds are coming from places totally unrelated to where your speakers are at; it's worth buying a copy of Roger Waters' Amused to Death just to hear how much your imaging perceptions can be toyed with by electronic processing (the fact that the music is cool is a bonus).

The only such processing I've even been impressed enough with to actually buy was a Hughes Sound Retrieval System (SRS) AK-100. SRS is based on a very complicated model of your hearing that takes into account lots of factors beyond simple cross-feed. For example, start rubbing your fingers together about a foot in front of your head. Continue while moving your hand in a circle around your head at that same distance. Notice how different the tonal balance of that sound is at the side of your head from how it sounds in front or behind you. That's right, your ears have a different response curve to sounds from the side than they do from the front. Hearing oddities like that all factor in to how we localize what we hear.

What does this have to do with headphones? Lots. Headphones really do beam the sound directly into each of your ears, so there is no cross-feed. You don't get sound bouncing around the room and hitting your ears from many different angles. All these things that contribute to the effect we call imaging and the construction of a soundstage just don't happen. HeadRoom claims that this situation causes your brain to work overtime attempting to place things in space, which is not possible with the limited amount of locational cues it's receiving. The result is mental stress and fatiguing listening. All of the HeadRoom amplifiers feature cross-feed circuitry that delays the sounds a bit before introducing them to the other ear. The result is that the mental picture you get when listening to headphones is smoothed out. Instead of very distinct left, right, and center images inside your head, headphones give a more natural left to right spread of sound with the HeadRoom processing engaged.

Chip off the old block

There are lots of components that have headphones jacks on them. You can find them on CD players. You sometimes get one on a preamp or receiver. It's possible to add a headphone output to just about anything with a few cheap parts; get yourself a little op-amp, hook it up to a jack, and you're off and running with headphone sound. Oh, sorry, did you actually want good sound from that? That's going to cost you. See, headphones are made out of the same types of parts you make speakers from. As such, you run into the same problems you have driving speakers with normal amplifiers--varying impedance, reactive loads, you name it. To properly deal with such things, you need to have an amplifier with a good power supply that can pump a (relatively) large chunk of current to drive your headphones.

You will not find such an amplifier driving most headphones jacks. There are some exceptions. The best headphone jack I'd ever used before was on an Adcom GTP-400 preamp. That one actually used the same transistors as Adcom's big power amps to drive the headphones with. This gave considerably more power to the bass on the Sennheiser phones I was using at the time, and was just all around better than the headphone output on my CD player. HeadRoom's amplifiers all use op-amps from Burr-Brown in them. While op-amps are not normally renowned for their audio prowess, they're sufficient for the amount of current needed for headphone use--but only if you get good ones. The Burr-Brown 604 used in HeadRoom's less expensive products is about as good as audio op-amps get. The more upscale Headphone products incorporate the even better Burr-Brown 627 op-amp.

Little HeadRoom

$249.

The least expensive unit in HeadRoom's stable is the Little HeadRoom. The unit itself comes in a very small (about three inches wide), approximately cylindrical enclosure. The back panel has a set of RCA jacks for the single input. The front includes the headphone jack, a volume control, and two switches to control what processing the unit does. It includes everything that's unique about HeadRoom's units, but with some corners cut to keep the costs down. As you move up through HeadRoom's product line, the main thing you get is a better power supply. The Little HeadRoom comes with a small, unregulated supply in the middle of the power cord; it looks like your standard wall-wart, but is easy to plug in. More expensive units can run off battery power or utilize beefier, regulated power supplies. In fact, it's possible to upgrade the Little HeadRoom for another $249 to create the Little w/More Power, which goes for $449 if you buy it that way in the first place. You don't actually get a bunch more output power with these upgrades; the extra power is aimed instead at better sound quality. Since HeadRoom's units are more like preamps than anything else, power supply concerns are critical.

Speaking of which, you can use the Little HeadRoom as a preamp. Get yourself an adapter that converts the stereo headphone jack into two RCA plugs, and you've got a single input preamp. HeadRoom will sell you such a preamp adapter for $2.99. Not knowing to ask for one originally, I picked up a seemingly identical part from Radio Shack for $3.49. Since I'm much more familiar with preamps than with headphones, I tried out the unit in that capability before getting into new territory. The Little makes a very good preamp for $249, if you can live with only having one input. Compared with the $600 Rotel RSP-960AX I normally use, the only area the Little was obviously inferior was the lower bass. It just didn't have the same authority at the bottom end, with more difficult bass sections sounding mushy and ill defined. This is really no surprise, because bass reproduction is usually what suffers when the power supply isn't particularly strong.

The other concern I had with using this unit as a preamp concerned the volume control. While the knob itself has a great feel to it, and seems of excellent quality, I did notice a bit of channel imbalance at lower volumes (this is common with inexpensive preamps). This was never a problem with regular headphone listening. But when I hooked up the Little to a high output power amp driving very sensitive speakers, I couldn't play the combination at a lower volume. One of the channels just didn't play until I turned it above a certain threshold, with appropriately balanced stereo appearing above that. You're not likely to run into this, but it is a possibility if you have a low volume torture test system like the one I noticed this in. Considering what the Little costs, and that being a preamp isn't its main purpose, you really can't complain about the small weaknesses it has in that application.

Due Processing

Continuing to avoid general sound quality issues, let's check out the processing available. The first switch to try out is the HeadRoom function itself, which sounds a bit funny unless you're wearing headphones. When I first flipped the switch on, I was expecting some dramatic expansion of the headphone sound. If that's what you expect, too, you'll be disappointed. The effect is subtle enough that some recordings don't seem a bit different as you toggle the switch. After spending some time listening to both settings, what the processing did was more apparent. You don't get the image jumping outside of your head or otherwise radically changing size. What you do notice is that the sounds you hear form more of a traditional soundstage, where you can place things in a continuous space. In comparison, regular headphone listening seems clumped up into sound blobs at each ear.

The other switch engages the mysterious filter. The effects of that circuit are harder to pin down. According to HeadRoom, their cross-feed processing tends to roll off high frequency mono sounds, making the overall sound warmer. The high-pass filter rolls off low frequencies to match when engaged. Whether you really need this feature turned on depends on the recording you're listening to. In general, they recommend using the filter if the sound is too warm, and turning it off if it's too bright. After playing around with it a bit, I decided that using the filter or not depends on the headphones you're using, the recording, and personal taste. You are going to have to try it yourself to decide how frequently you want to utilize it.

Between the HeadRoom processing and the filter, I was usually able to get something I was happy with regardless of the headphones or recording. I never suffered from the nasty long-term listening irritation I've always had with headphones before. I couldn't say for sure why. It might be the smoothing out of the soundstage from the processing. It could be the adjustable tonal balance slides. Or it just might be that all I really needed was a headphone amplifier that didn't distort so much. Maybe it's a combination of all three. In any case, the Little HeadRoom always made for much more enjoyable headphone listening than the traditional budget equipment headphone outputs I've tried. How much more enjoyable really depends on the associated equipment. One obvious question is what headphones you should use with it. Let's take a look at some of the models from popular audiophile manufacturer Grado.

Grado SR-60, SR-80

$69 for SR-60, $95 for SR-80. 32 ohm impedance, 94dB sensitivity

You can pick up a pair of Grado headphones for not much more than decent cheap headphones go for. Whether they are worth the extra money is a somewhat complex judgment. There are a couple of trade-offs involving sound quality, compatibility, and comfort to consider.

When I first tried out the two pairs of Grados, I started with the SR-60 phones plugged into the Little HeadRoom. These sounded pretty good, but nothing really spectacular, I thought. Switching to the SR-80's gave a much better impression; those sounded great. Unfortunately, they didn't feel nearly as good. The SR-60's come with a full-size ear pad that covers the entire driver, nicely cushioning your ear. Stock SR-80's have a donut shaped pad that leaves the center of the driver open; this doesn't feel nearly as pleasant. Since the pads are removable, I decided that suffering with the SR-80 donut was hardly necessary, and I swapped the pads.

A few weeks later, I decided to compare the SR-60 and SR-80 units again. Oddly, I didn't notice nearly as much difference between the two this time; the SR-80 wasn't a big jump in quality anymore. I thought at first I was just misremembering the magnitude of change, but further investigation revealed the real cause: the big comfy cushions sound noticeably worse than the donut pad, sucking much of the life out of the sound. The bass impact is gone, the midrange isn’t as clear, and the dulled top-end makes imaging suffer. There is almost as much of a qualitative change between the two pads as there is between the models themselves. Ranking the different combinations, SR-80s with the donuts are the best; SR-60's with the donut and SR-80's with the comfy pads are almost equal, with a slight nod toward the SR-80; and SR-60's with the comfy pads are the worst.

So there are really two things you get when moving up to the SR-80 from the SR-60. The more expensive driver is more dynamic and has deeper bass. You also get better sounding ear cushions to go with it. After trying both pads, I really can't pick one over the other as a clear winner--for critical listening, the donut is the way to go, but I hate to wear the phones for long periods when using it. If you buy Grado phones, I'd recommend getting a sample of each to try out for yourself. One compromise suggested by HeadRoom HeadHoncho Tyll Herstens is to cut an approximately nickel sized hole in the center of the full ear cushions, which keeps them comfortable but lets the higher frequency material pass unimpeded.

Tickle Me Ear

How do the Grados sound? Well, that depends greatly on what you've got them hooked up to. Right now, my main music system consists of a Rotel RCC-940AX used as a transport with a CAL Gamma DAC, Rotel RSP-960AX Preamp, Warner Imaging 401S Power Amplifier, and Magnapan MMG speakers (using all DH labs cables except for the Monster Toslink connecting the DAC). When I hooked the Little HeadRoom up in place of the preamp and drove the Grados with it, they sounded amazingly close to the Magnapans in quality. Excellent sound at all frequencies, with a very detailed treble and fast response to transients. If you've got a good front-end and are using a HeadRoom amp, I'd definitely recommend either Grado, with the SR-80 well worth the extra money considering how much more authoritative the bass is (this makes the treble sound less forward, too).

Unfortunately, not everyone has such a setup; even if you do, it may not be available at some of the times you'd like to use headphones. When I switched to using the headphone jack on some inexpensive CD players (a few Sony units, home and portable), the Grados sounded flat and lifeless. The bass was limp and treble ragged. Now, is that the fault of the poor source or the poor amplification? We need more headphones to figure that out, so I tried a couple of different models from Sennheiser, the company I've always bought headphones from in the past. I rummaged through my collection, borrowed some, and ended up with a few 400 series models (most at least a couple of years old) that originally ranged from $70 to $100, right in line with what the Grados cost. They all sounded considerably more alive and dynamic with the cheap headphone output, without the ragged treble. And the bass was more full. Actually, with the cheap portable CD players I tried, the Sennheisers were a better choice for yet another reason. The Grado phones gave me a better view into the high-frequency output of the player, which frankly was better left hidden. The more laid-back presentation of the Sennheisers didn't call as much attention to the flaws of the less expensive gear. And if you ignore sonic concerns for a minute, Sennheiser is the clear winner in comfort.

HeadWrapup

I wasn't surprised to find no clear winner comparing headphone brands. The recurring theme I point out in The Entry Level every month is that you can't judge components as being better or worse than their competition in a vacuum; some context of what you're going to be using them for is needed.

The Little HeadRoom does a terrific job at fixing a very specific problem. It's not a particularly flexible unit, in that it only has one input and it needs a wall outlet to run. At $249, I wouldn't go so far as to say it's a bargain, considering it's a product with such a small range of applications. But when you look at the quality of parts used and how good the unit is in its domain, I do consider it a good value. All of HeadRoom's products are similar values in my mind. If you want a portable unit from them, you need to spend at least $399 for the Supreme HeadRoom. That's a very flexible component you can use in lots of applications, but it's certainly not cheap. You are getting a good deal with their products, but there's no free lunch here.

The Grado headphones are excellent, if your headphone amplifier is capable of keeping up with them and your source is good enough that you really want to hear it so clearly. I'd have to do some more extensive comparisons with current production Sennheiser phones before I would give a specific recommendation on those, but they certainly should be considered if you're trying to put a headphone system together.

If you want to find out more about HeadRoom specifically or headphones in general, you should spin by HeadRoom's home page. You might want to get a copy of the printed booklet describing their products, too, especially if you're on a less than speedy Internet link and tire of waiting for all their cool but bandwidth intensive graphics to load. The HeadRoom brochure stands out as one of the best examples of informative audio product literature I've ever read. The sales material is punctuated by lots of accurate educational material that gets you up to speed on the real issues you should be considering. There are some things I left out of this article because they're covered there in plenty of detail already. I should warn you, though, that HeadRoom makes a very good case for why you should spend serious money on a headphone system; it's a dangerous place for your wallet to visit, even if it is good for your ears.

.....GS (gsmith@westnet.com)

Late Breaking News: Currently the Little Headroom is Headroom's lowest priced headphone amplifier. Headroom has informed us of a new budget headphone amp to be released very soon priced at $179 . For more information please contact Headroom Corporation (DAS).