The Hardware Dilemma and HRA

Yesterday’s post hit a nerve for a few readers. I can imagine their concerns; “maybe my setup doesn’t measure up” to real hi-res standards. A couple of you sent in lists of your equipment (thanks to one that included links to the product pages so that I could quickly scan the specs) and asked if your rig was up to the task. The answer is simple…if you enjoy the sound of the music played back through your system in your environment then don’t worry about whether your setup meets the requirements of hi-res audio. There are very, very few recordings that deliver fidelity that eclipses that of a compact disc.

In reality, the equipment that I have in my studio and house don’t measure up either. However, I’m able to mix and master my AIX Records titles and other projects without any concerns over quality. I have a Bryston 9B power amplifier (I also have a 4B stereo amp from Bryston that has been on for 20 years and has performed flawlessly). Are there better amplifiers out there? Absolutely. But when I was selecting the equipment I wanted to have in my room back in 1989, the criteria included reliability as well as the sound. The amp doesn’t exceed 20 kHz but keeps the noise levels very low.

The Bryston drives my 5 B&W 801 Series III speakers. These are old speakers…but have been part of my professional life for many years. They aren’t the new JBL M2 studio reference monitors or the Revel Salon 2 that we had in Chicago at the AXPONA show, but they deliver really great sound. Would I love to upgrade to the M2s or the Salon 2s? Sure, but I can’t afford it.

The simplest way to experience real high-resolution audio (assuming you’re playing back one of my own productions and not a hi-res transfer) is using a file player running on a computer to an external DAC with a great headphone amplifier and a great set of phones. I’m not a real fan of headphones…I don’t listen to music through phones except when I’m on a plane. But I would put my Mac Laptop running Amarra, to a Benchmark DAC 2 HGC (connected with a good USB cable…avoid the esoteric, expensive digital cables!), and then plug in a set of Grados as a viable hi-res system. Sony and Oppo make headphones that meet the high-res audio specs but I’m partial to Grado phones.

If you’re like me and prefer to have your sound reproduced through amplification and speakers, you’re going to spend more money. I’ve set up dozens of superb quality “high-resolution” audio system at trade shows and other venues. I’ve had systems with B&W 800Ds (yes, I had 5 of them in Florida years ago driven by Boulder Power), Thiel CS3.7s, German Physiks Emperors, and a very nice sounding system with Piega speakers a few years ago, but the best overall integrated system was the last one that I assembled with the help of Benchmark and Revel. Some of you got the chance to hear it.

I made a pretty big deal about the system we put together in a few posts from last April. My friends at Oppo supplied a modified output board so we could connect a full 5.1 channels at 96 kHz/24-bit PCM audio via three S/P DIF to three DAC2 HGCs. We used DH Labs cables. The balanced outputs of the Benchmark DACs were sent to the inputs of 5 monobridged AHB2 power amps and then to 5 Revel Salon 2 speakers. As far as I’m concerned this was the first and only system that I’ve put together that had the potential to reproduce my recordings without any weak links or compromises. We had dynamic range past 130 dB, frequency response to 40 kHz, and jitter free PCM audio through 5 speakers and two subs.

It’s true that the acoustic environment was severely compromised compared to my studio or a nicely balance listening room, but we did something that no other demo room has every accomplished and it sounded amazing.

Of course, there are lots of other ways to get there. But at the end of the day, the gear is secondary to the production of the music. I’m a music guy…if it isn’t on the tracks then it isn’t going to get played back.


Mark Waldrep, aka Dr. AIX, has been producing and engineering music for over 40 years. He learned electronics as a teenager from his HAM radio father while learning to play the guitar. Mark received the first doctorate in music composition from UCLA in 1986 for a "binaural" electronic music composition. Other advanced degrees include an MS in computer science, an MFA/MA in music, BM in music and a BA in art. As an engineer and producer, Mark has worked on projects for the Rolling Stones, 311, Tool, KISS, Blink 182, Blues Traveler, Britney Spears, the San Francisco Symphony, The Dover Quartet, Willie Nelson, Paul Williams, The Allman Brothers, Bad Company and many more. Dr. Waldrep has been an innovator when it comes to multimedia and music. He created the first enhanced CDs in the 90s, the first DVD-Videos released in the U.S., the first web-connected DVD, the first DVD-Audio title, the first music Blu-ray disc and the first 3D Music Album. Additionally, he launched the first High Definition Music Download site in 2007 called iTrax.com. A frequency speaker at audio events, author of numerous articles, Dr. Waldrep is currently writing a book on the production and reproduction of high-end music called, "High-End Audio: A Practical Guide to Production and Playback". The book should be completed in the fall of 2013.

23 thoughts on “The Hardware Dilemma and HRA

  • If the room isn’t right the reality of good music is butchered. Spend some time on your room acoustics. I’d rather have midfield equipment with a great acoustically treated room, than esoteric $uber buck equipment in an untreated space. This plays itself out in every case, recording quality aside.

    • I’m getting to that. Although, I must say that I’ve managed to make some pretty awful rooms sound great in 5.1 surround. Ballrooms at a hotel are not ideal.

  • craig allison

    Your comments re: headphones are very pertinent given the current trend. I go way back with ‘phones. bought Koss ESP-1A electrostatic models when I was 17,(yikes, 47 years ago !),and understand the value of good headphones in the listening experience. The inner fabric of the music is revealed, no room issues, great intimacy, all virtues. But I say the same thing over and over in different ways: Quality Loudspeakers are still the best way to listen, for one simple reason above all; music is as much to be felt as heard. While phones can have good low end response today, the vibrations travel no further than the bone structure of your head, neck, and shoulders will allow. Someone put it this(crude)way the other day ” If I punch you in the stomach, you won’t just hear it”. Without loudspeakers, no amazing 1960s’ music, no Woodstock,(500,000 pairs of headphones-NOT!),no Jimi Hendrix, no energy for positive social transformation; just think about it. Today’s headphone crowd will have their minds blown the first time high quality loudspeakers come home, where the best hi-fi listening happens.

    • Why is it that a large majority of us that are seriously interested in audio are also eligible for Social Security?
      At today’s prices for high end gear we need a raise in our SSI checks. 🙂

    • There”s also the issue of soundstage. I love my phones for all the reasons Craig stated but have never appreciated what some guys talk about soundstaging with phones, I don’t hear it, not in the way speakers can.
      I love listening to a well setup stereo speaker system, the kind where you turn off the lights, close your eyes, and could swear there was a group of musicians in front of you playing. Well produced minimalist recordings played on a well setup HiFi speaker system is a big part of the enjoyment of high end stereo.

  • Robert McAdam

    Its always been about having both power amplifiers that have decent power supplies and a quick response circuit and speakers that are efficient more than 90db, built with quality frames and magnets with high current capability.
    This has been my philosophy for 40 years. This approach has never been cheap as quality power supplies tend to be heavy and large. Same as quality speaker drivers with lots of metal and magnet in solid cabinets.
    Switched mode power supplies seem to be gaining ground these days.
    In saying this a lot off so called Hi-Fi quality amplifiers and speakers are not in the ball park and never have been.
    Bryston, B+W, Tannoy Studio, Boulder Amps, Plinius Amps, Classe Amps, to name a few brands that make good stuff.

    Generally the stuff made for the Professional Audio market is better sounding and better priced than the home Hi-Fi market. This is how I came to own the Benchmark Dac1 which was excellent value for money compared to the Meridian Dac 506 which were 3 times more expensive and didn’t sound as good in the 90’s.


  • Camilo Rodriguez

    Hi Mark,

    I have to say that I’m surprised that readers that have followed your wonderful effort and epic task on REAL HD-AUDIO, weren’t aware of the specs of their own gear and the threshold of audio transparency and/or the minimum HRA spec requirements.

    I have been listening to the extremely limited high-resolution material available on my DAC2 DX, Violectric V281 headphone amp, Sennheiser HD800 and Audeze LCD-X headphones for almost a year now, but I have to say that what makes the most significant difference is still provenance.

    My classical music sounds light years better than most of my Jazz, Rock and World Music recordings, which are almost 100% multitrack studio recordings with tons of effects, overdubs, aggressive mixing and mastering, audio compression, colored mic preamps, etc.

    The Classical recordings from labels such as Carpe Diem, 2L, MA recordings, Glossa, L’empreinte Digitale, Aeon, Ramee, alpha, Christophorus, Aeolus, Hyperion, Channel Classics, Acousence, CPO, MDG, Analekta, etc., with minimal mixing and mastering, apparently no or minimal audio compression, and most significantly, recorded in real acoustic spaces like churches, concert halls, etc., are immensely more enjoyable, natural sounding and less fatiguing than the usual pop, rock or Jazz recordings. To me, these are my high resolution audio recordings among today’s average recordings and industry practices. They may not all be ideal HRA, but they are such a quantum leap ahead of the majority of the recording industry practices today, that they represent the high resolution out there.

    My headphone rig is certainly the best audio setup I have ever owned, and although it doesn’t come cheap, it is considerably more affordable than the Revel Ultimas that you used at the AXPONA show. I can’t tell you how much I’d rather have that rig, but I really can’t afford it. I am very much considering to get the AHB2 and the Benchmark SMS1 monitors by the end of the year, though, and I’m pretty sure they can put a big smile on my face although they certainly don’t go down to 20Hz or beyond 22kHz. Nevertheless, as you very well pointed out, the joy of listening to music is first, not the resolution it is recorded at.

    On the other hand, aside from the Benchmark AHB2 and Mola-Mola audio’s Kaluga monoblock Amps, I know of no other Amps that can deliver full HRA specs to a pair of speakers. The Kaluga mono blocks cost several times the price of the AHB2, and are based on Bruno Putseys’ Hypex nCore Amp modules, which have recently been adopted by several manufacturers like NAD, and who are certainly trying to step up their game towards HRA specs. Benchmark’s AHB2 is by far the most affordable and best performing Amp on the market today, and it truly is a Benchmark.

    An analogous reality, as I have insisted before in other comments, is to be found among recording audio and professional gear. There are few mic preAmps, and even fewer microphones (DPA, Earthworks and Sanken) that can handle HRA specs as defined by the JAS. Aside from Benchmark, Millenia, Grace Design, and two or three more mic preAmp manufacturers out there, there’s no more mic preAmps that can handle true HRA specs. There might be more A/D converters that can do HRA, but you’d run out of converters before you run out out of fingers counting. This situation has to change just as much as that of consumer and audiophile audio components if we are ever going to get true HRA.

    Not to just repeat previous comments, I have a question regarding the AXPONA setup, and the bi-Amp functionality of the Revel Ultima speakers. Is it best to bi-Amp the Revel Ultimas with a pair of AHB2 per speaker, or is it sufficient to use just one AHB2 per speaker to drive the Revel Ultimas?


    • Thanks…excellent comment. I hope you include AIX in your list of good classical labels.

      • Camilo Rodriguez

        AIX records is definitely in my top 10 list; I just wanted to mention the lesser known yet outstanding European labels that many Americans may not have found out about yet.


        • I know…I was just giving you a hard time. Thanks. These other label do some excellent work.

  • “We had dynamic range past 130 dB, frequency response to 40 kHz”

    I’d really like to know how you came up with that figure? The average good listening might have a background level of around 40dB. To have a real world listening dr of 130 your system would have to be capable of 170 dB peaks??????

    Do you consider a set of phones (or speakers) capable of 40 kHz HD ready?

    • I’ll be talking about rooms and acoustics soon. You’re right that the ambient noise in a space is a major factor. But it doesn’t mean that the system has to start at the background level and go up from there. Sure, the dynamic range is affected…diminished…but I don’t tailor my recordings to match the environment. COmmercial recordings are another matter.

  • Kevon Manuel

    Well the next question will be: How do I know if my room sounds good? What and how should I treat my room? I’m beginning to think going the headphone route would make life way easier.

    • Headphones are definitely easier. I’ll be writing about room acoustics soon.

  • Although your Bryston amp may not be rated beyond 20 kHz, it’s frequency response won’t fall off a cliff beyond that point. Maybe it’s 6 dB down at 40 kHz. Frequency response of the analog electronics is rarely going to be a problem. For frequency response, as I think you’re well aware, the transducers – loudspeakers or headphones – will be the most likely equipment bottleneck. Resorting to headphones is not likely to help. Headphone manufacturers rarely give a window for their frequency response measurements. It’s reasonable not to do so, because there’s no agreed-upon target curve for headphones. When a manufacturer claims response up to 40 or 50 kHz, you can bet it’s way way down by that point. For example, Oppo’s specification a 50 kHz for the PM-1 refers to the driver on its own – not how it behaves in the headphone. Measurements across multiple publications show the PM-1’s frequency response to take a nosedive after about 13 kHz. These are very nice sounding headphones – a bit on the warm side of neutral – but you’re not going to hear all of the partials of a muted trumpet through them. Some other headphones might make it to 15 kHz, but I can’t think of one that isn’t well down by 20 kHz. (It’s possible that some of the measurement tools used on headphones aren’t designed for extremely wide bandwidth, because they originated in audiology research, but others are capable.)

    As you found when setting up your demo room for Chicago, achieving high resolution specs, in both dynamic range and frequency response, requires some pretty special equipment. It safe to say that no mass-market receiver, and very few loudspeakers, are going to make the cut.

    • Thanks for the additional information on amps and microphones. Of course, in the analog world everything has a soft change as we reach boundary conditions. If someone wants a crazy good HRA system, it is possible be challenging.

      • Camilo Rodriguez

        Absolutely agree with Andrea’s comment, if you take a look at the headphone measurements made by Tyll Herstens at Innerfidelity, the very best measuring headphones Sennheiser HD800s, Stax SR-009s, AKG K series and Audeze LCDs with Fazor tech) barely make it to 20kHz and very few hang on for a little past 20kHz, but are already way down. Most take a dive between 10 and 13kHz.

        The certificate I got from Sennheiser is diffuse field – and almost perfectly flat – frequency response measured from 100 Hz and 12.5 kHzand, and the one I got from Audeze is from 20Hz-20kHz, but as Andrea mentioned also takes a small dive around 10kHz, to recover and be almost up again for 20kHz.

        The Revel Ultima are probably among the very few speakers that can handle HRA specs, and I’m pretty sure you can’t even count 5 speakers in this league.

  • Agreed on the Grado recommendation!

    The value proposition is exactly why I got into headphones. Even if I bought the absolute best of the best headphones, amplifier, DAC, etc… I still would have spent WAY less than on a comparable loudspeaker set-up. Listening to music on great speakers is wonderful but too hard on my wallet. Given my budget and preferences, I prefer to put my money into higher-end headphones and associated equipment than into middle-of-the-road speakers.

  • Mark, looking at your own equipment list, the Bryston does in fact go “flat” to 60KHz (-.5dB @60Khz into a “speaker” load), but the B&W speakers probably don’t, with tweeter response getting ragged already at 16KHz, but I couldn’t find test data above 20KHz. The problem with doing better than CD performance is really the speaker. If they actually do have response above 20KHz, it gets very, very directional. That energy won’t reflect around the room well, so if you don’t have your head in a clamp at the sweet spot, you’ll be at CD response or less.

    And this is what’s been puzzling to me about high res audio. In a room, we can’t reproduce the dynamic range of a CD, much less real 24 bit. We can’t get even the high end of a 96KHz file out into the room to our ears. Even most headphones won’t do it. So, what are we doing/hearing?

    I suspect something along the lines of “spectral contamination”, (re: Deane Jensen’s 1988 AES paper), or the lac of it in high res audio. The short version is, band-limited systems cause a specific type of intermodulation distortion that folds down into the audible band, not as traditional IMD, but measurable with a complex multi-tone signal. Well designed wide-band systems don’t do this as much.

    But the, we have the speakers….ugh.

    Looking forward to your thoughts.

  • Dimitris

    Hi Mark,

    What DH Labs cables did you use?

    • Admin

      I’ll have to ask the guys over at DH Labs…stay tuned.


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