RBH HP-2 Measurements and Conclusion
Here is a quick and dirty way to measure over-ear headphones using a foam head at a Michael's, which is a local crafts store. Let's call him Mr. Bob. The microphone was placed inside of Mr. Bob's ear while the HP-2s were placed over his head to conduct the measurements.
Mr. Bob simulated head for On-Ear Headphone Measurements
RBH HP-2 vs Sennheiser HD598SE Frequency Response Graphs
The RBH HP-2 were compared to a known reference, the Sennheiser HD598SE. The sensitivity of the Sennheiser is about 7dB lower than the HP-2, which doesn't surprise me. As I said before, the HP-2s play hellishly loud with very little input. What is interesting about this graph is how the HP-2s follow a target room curve for loudspeaker playback systems. According to Harman research, good headphone and speaker response should be very similar when measured at the ear. You want a slightly elevated but flat bass response with a gradual tapering off of the high frequencies. This profile is what made the HP-2s sound warmer and fuller than the comparably priced Sennheisers. I also found this to be the case when compared directly to the more expensive Oppo PM-1 headphones. The PM-1's were both less sensitive and had less bass output than the RBH HP-2s.
Too Much Bass? Here is the Solution
For those that prefer less bass from their HP-2s, you have three options:
1. Use a tone control to dial to preference
2. Seal the ports with silicone (semi-permanent solution)
3. Electrical tape over the ports (as needed)
Sealing the ports with silicone does work nicely to maintain a finished look but once you do it, it's diffuclt to reverse . Thus I highly recommend to instead use black electrical tape to seal the ports as desired. That way you can always take the tape off when you desire more bass from source material that sounds a bit anemic. My personal preference was to cover just one port on each side with electrical tape for bass heavy program material. It was very easy to apply and remove as needed.
RBH HP-2 with ports sealed for reduced bass
Here is the port plugging procedure:
- Use your fingers or tape (scotch, masking, electrical etc) to initially cover the wholes while listening. Experiment with covering 1, 2 or 3 holes to see how much reduction in bass you prefer.
- Once you have decided how many holes to cover, put a little bit of GE black silicone (or any other brand of black silicone you can get at your local hardware store) onto the tip of a soft cloth. Lightly rub silicon into the holes you want to fill.
- Wipe excess silicone off of headphone. It will come off very easily.
- VERY IMPORTANT! Let silicone dry an hour or so before using headphones.
- Done! You now have modified the tuning of the headphone chamber to give you the low frequency response you prefer.
RBH HP-2 Frequency Response Comparison
blue trace: ports open red trace: ports sealed
As you can see, sealing the ports significantly reduces bass response (about 4dB below 150Hz) but also bumps up the 250-400Hz range about the same amount.
Editorial Note About Bass in Headphones:
Directly comparing open-back headphones (Oppo PM-1s) to closed-back headphones (RBH HP-2s) is not an apples to apples comparison. Open-back designs generally have less bass response than closed-back for one thing. Bass response is not exactly the strong point of the planar magnetic technology that the PM-1s utilize due to the low mass of the diaphragm. Dynamic headphones tend to have much stronger bass but planar magnetic headphones usually have better distortion performance. These were exactly my findings when comparing the PM-1s to the HP-2s. A better comparison would have been a pair of PM-3 closed-back designs from Oppo or better yet, a pair of other closed-back dynamic headphones. But I used what I had on hand just to get an idea based on a known reference.
As good as the RBH HP-2s are, they aren't perfect. Despite these being ultra-lightweight headphones, they quickly caused me ear fatigue when wearing them for more than 30 minutes at a time. I soon realized the headband had too much tension to comfortably accommodate my largish head. I informed RBH about this and they suggested that I bend the metal extension glides out a little. After doing this, I had no problems with comfort. I suspect others will run into this issue so I'd recommend before sending them packing before the 30-day trial period is up, give this fix a try. I do hope RBH looks further into this and upgrades to a wider headband to eliminate this issue entirely.
The HP-2s provide a good deal of noise isolation as promised, thanks to their closed-back design and the snug seal they make when coupled to your ears. Noise isolation is another advantage closed-back headphones have over open-back designs, though the very nature of their design does sacrifice a bit of naturalness and openness to the sound. I found the HP-2s did a commendable job isolating me from a noisy room of kids playing XBOX or my in-laws watching Spanish Soap Operas. If you do all of your headphone listening in environments like this, then a closed-back design is a must.
About the only time I didn't appreciate the noise-isolating benefits of the HP-2s was when I placed a call in a quiet environment and could hear my voice muffled. In those situations, I much preferred to just take them off and use the speakerphone feature of my phone.
The RBH HP-2s are about the best pair of over-ear cans I've heard at this price point. They do so many things right that they simply shouldn't at this price that it's almost frightening how far headphone technology has come in the last few years. What they lacked in refinement and maturity of my Oppo PM-1s, they made up for in droves in sensitivity and bass response. I suspect RBH is targeting the Beats shopper with the HP-2s. While they may not have the brand or fashion appeal, the HP-2s offer a much better balanced and better sounding pair of headphones for the dollar. The bass and comfort tweaks I suggested previously should broaden the appeal of these headphones.
The HP-2s are a solid first over-ear headphone offering from RBH and at just under $200 at the introductory price, they are an absolute steal. You just may want to scoop these up before the price goes up to $249. I'd love to see their product line evolve with higher-end over-ear open back headphones that will continue to build on this incredible foundation laid out by the HP-2s. Until then, you can rest assured that these are the real deal!
RBH Sound HP-2 In-Ear Headphones
MSRP: $249/pr (free shipping)
About RBH Sound
RBH Sound, one of the older speaker companies in the USA, is still run and operated by the original founder - Roger Hassing. In 1976, RBH Sound produced its first loudspeaker. RBH soon began to OEM for McIntosh, (back in the days of Gordon J. Gow), providing cabinets for their speakers. This set the stage for doing a superb job since McIntosh didn’t worry about how to cheapen the product, but to make it better and, at least at the time, lead the class in performance. Later, RBH Sound began producing loudspeakers for a retailer in Los Angeles called Northridge Audio. They didn’t advertise or market these products to avoid a conflict of interest with their other OEM customers (i.e. McIntosh, Parasound, Fosgate, etc). People nonetheless sought them out because of their high performance, which lead to a good success story and response for their products. Over the years, RBH Sound was successful at helping other companies in achieving their goals. Based on their strong engineering background and sourcing ability, they took it upon themselves to enter the market under their own banner.
The Score Card
The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:
Performance × Price Factor/Value = Rating
Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.
Audioholics Rating Scale
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Recent Forum Posts:
I will say that from the first time I tried them to now (about 100+ hours of break-in later), they have changed in their tonal signature. At first, they were very noticeably a phenomenal bass-reproducing set of headphone. Perhaps some of the most capable, extended, and realistic bass reproduction I've heard in any set of headphones. What they initially lacked though was a matching treble presence. It seemed to be rolled-off at about 2.5-3 kHz and above. For example, chimes, and delicate triangle were barely audible deep in the mix, compared to my reference headphones and loudspeakers on tracks where they were much more present in the mix. Over the break-in, the upper mid and higher registers have improved almost daily. So if your initial impression is these are very dark ‘phones, don’t conclude that it will always be that way. But in general, they so have a warmer balance than other more neutral headphones.
They have a different overall tonal palette to my Focal Elear. These give a huskier, drier character to most vocalists and to the midrange a certain body and thickness. They sound balanced in the overall frequency - not like they have any augmented or boosted characteristics in any given bandwidth. They are vastly better than the Sennheiser veiled and low-mid humped HD650's. I know a lot of people consider the HD650's a reference standard, but they sound artificial to my ear, I would even call them “colored” in their treatment of just about any song played through them. I got fatigued with them after a month and ditched them.
However, the HP-2 are definitely an acquired taste. They reward you with a sumptuous and revealing low-end presence. The soundstage is a bit compressed on some recordings, but if you have access to good binaural material like Dr. Chesky, it is very respectable in location, depth and pinpoint imaging. What you do give up a little with the HP-2 is an equally balanced upper and high-end register. I'm not saying it's lacking but compared to how effortlessly the bass can reveal even the most complex harmonics and overtones of say Marcus Miller's or Victor Wooten's bass guitars, the mid and high-end provide accurate, and realistic reproduction too. It just has less dramatic impact to your sense, which ain't all bad or you might get fatigue from the assault. I guess I mean the bass just sucks you in and is so attention drawing because it does it so well, that the mid and upper “almost” seem like a let down. I can't really describe it except to say, the bass is far superior to just so many headphones. The mid and upper are every bit as accurate as an HD800, Focal Elear or Audeze LCD-4
What would I change? The earpads are a bit too small. I wish the cups and inner hole was larger because the clamping pressure sometimes get my upper eartips a bit uncomfortable after several hours of wearing them. And while I like the High Rez cord, it transmits microphonics, yeah. That means if you rub against or tap the cable, you hear it in phones. So the shielding si insufficient. And I wish it was about 1 meter longer. Make the other cable 1.2m for mobile smartphone use. But a High Rez cord, for home listening, needs a little more length like 2 meters. These are minor gripes, especially at this price point. These are way more comfortable than the HD650's which clamped my head to the point of jaw and ear pain. They're very light. They are sometimes a little creaky. The swiveling joint on the phone assembly can impart some movement noise as it adjusts angles on your head. I wish the connector at the headphone end was angled either 45 or 90 degrees to keep the cable connector from hitting my collar and making noise. Again, minor nits.
Soundwise, if I were to change anything it would be the 7-13 kHz region. I think the beryllium diaphragm advantage (eliminating cone breakup at high frequency bandwidth) is not being taken full advantage of here. Those instruments that live in that territory: the triangle, bell, bell chime and other delicate high-register instruments seem to be harder to discern in the overall music, and not as naturally and effortlessly reproduced.
They do sound pretty good, though. Nothing spectacular, but the bass is on point, so they appeal to my sensibilities.