Dr. AIX's POSTS — 05 February 2015


This is going to be difficult. I’m reaching out to potential partners for the upcoming AXPONA Show in April and am finding it difficult to identify a system that can achieve the level of performance that my high-resolution surround recording require. Yes, I’ve been demoing my Blu-ray discs at the AXPONA Show for years (the founder and I have been close friends for well over a decade) and I have always pulled together a system that John Atkinson called, “the best sounding room of the show”. However, when you get right down to the audiophile nitty gritty…I’ve never shown the true potential of a bona fide high-resolution system.

Last year, we had a great room but I was disappointed in the final presentation. There was a room tuning system that passed my stuff from analog back to digital and then back again at 48 kHz. The speakers were less than ideal because of their omnidirectional distribution patterns and weren’t identical. But oh well.

Getting near real world dynamic range and frequency response in a stereo playback system is not nearly as challenging.

The goal is to move well beyond the performance of a standard compact disc. We know that a 44.1 kHz/16-bit Redbook PCM audio stereo CD is capable of delivering fidelity up to 93 dB of signal to noise ratio and frequencies up to the Nyquist Frequency or 22 kHz. Compact Discs can deliver absolutely terrific sound. But real high-resolution audio moves the bar past CD spec and has the potential to deliver real world sound…sound the matches or exceeds the capabilities of our human ears and brain. That’s been my mantra for over 15 years.

I was amused during the David Pogue Pono review and “test” to see the participants talk about hearing “maybe a 5-10% difference” between the sound of high-resolution audio files and the same tune played at AAC 256 kbps. David dismissed the described level of difference as if 10% was negligible. How many of us would be dancing in the streets if we could get a 10% improvement in the sound of our systems? That’s a huge improvement! Think of all of the accessories, power cords, surface treatments, disc cutters, and the rest of the useless tweaks that pretend to move needle 1%, if at all, and claim the improvement in fidelity is “astounding”.

The system I need to pull together in Chicago at the AXPONA show has to be able to deliver dynamics up to 125 dB SNR through 5 channels. My options include configuring a HTPC using a Lynx card that can output the HDMI of my Blu-ray discs to the JVC projector AND output multiple S/P DIF digital connections to three Benchmark DAC2 HGCs to the new Benchmark AHB2 power amplifiers and then to a set of as yet undetermined speakers that will output efficiently up to 40 kHz. I’m planning on using the Oppo BDP-103 as the front end and take the S/P DIF out for the high-resolution stereo presentations but it gets tougher in the multichannel world because of the lack of HDMI inputs in digital preamps.

Wouldn’t it be great to actually have a high-resolution capable room at the AXPONA that does multichannel up to the elevated specs that I strive for? I’m open to suggestions…just drop me an email or leave a comment. The time is now to reach out to partners and get this solved.

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About Author


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.

(34) Readers Comments

  1. Dr Waldrep, You’ve ID’d a working set of useful electronics. You may want to use two sets of speakers and enlist a helper. One set is the Benchmarks (5) and the other set is the large JVCs (2), you reported on last year (at least a pair). Make sure the JAS Logo is everywhere with the rules on the back of the card or next to it.

  2. Yamaha CX-A5000 with Genelec powered monitors

    • The spec sheet of the Yamaha didn’t include frequency range and the Genelecs don’t go past 20 kHz.

  3. Difficult it is, and your persistence is highly admirable. Putting across the idea of hi-res= noticeably higher Fi is hard enough, but also simultaneously trying to convince folks that multi-channel is where it’s at, That is biting off quite a chew Mark.

    I attended an AES meeting at Fantasy studios a few years ago. 5 top mastering engineers including Paul Stubblebine and George Horn (who mastered my LP) were talking about formats, past, present future. They said that mixing and mastering two-channel for an unknown quality of playback, speaker location, etc., was hard enough, and that the thought of trying to do this in multi-channel with all the lousy, screwed up “Home Theater” systems and so many more speakers of varying quality and location that it made rtheir heads swim.

    Your efforts are laudable, but who has the bigger challenge, you or Neil Young, that’s a good question that I can’t answer.

    • It’s a major challenge but surround is so much better than stereo…and since I don’t believe in mastering my recordings, I don’t worry about anything after it leaves my room. I had some big shots in the studio yesterday and they know surround…but they still commented on the amazing experience.

  4. I’m using an Oppo BDP-105D (the “D” is a waste of money) as my disc player, and I’m using the analog outputs into a Marantz AV7701 pre-pro, with the Marantz set to “pure” for the blu-ray input. To my understanding (which may well be incorrect), in that mode the Marantz passes the analog signals with no processing beyond level control.

    My front speakers are Emotiva Pro Stealth 8 studio monitors (I’m still saving up the money to put in good surround speakers). All told, that setup was around $5500 plus my own cables (S-video cables with gold contacts, including the XLR connections from the pre-pro to the speakers).

    I’m pretty happy with the hardware setup, and your Respighi and Steve March Torme DVDs sound very, very nice through them.

    I’m not sure why you wouldn’t use the Oppo’s DACs, unless the purpose of the exhibit is to show off the Benchmark DACs you mentioned in the article. For what it’s worth, the Marantz has a plethora of HDMI inputs, that I believe can be used for audio only (but I like the Oppo’s sound a lot, so I haven’t bothered digging into that option).

    • The Benchmark DACs are second to none in my view…but you make a good point.

  5. Mark, do you know Dan Laufman from Emotiva Audio? He might be interested. They have very powerful amplifiers and have recently released for sale an AV processor, the XMC-1, that has Dirac room correction. Give him a call. He’s a great guy and can probably help you even if he doesn’t want Emotiva to participate. If he is not available, ask for Lonnie, the chief engineer and designer. Good luck.

    • I do. Dan and I have been trying to connect on the phone.

  6. If you really want to drive the speakers to 125 dB SPL, you’ll need speakers with a sensitivity of 100 dB/W/m, even if running the Benchmarks in bridged mono (380 W into 8 ohms). Of course, you’ll be lucky if the room’s noise floor is below 40 dB SPL, so there won’t be any real dynamic range advantage from 24 bits over 16 bits.

    • All true…however, I want to be able to say I have a system that meets the highest possible standards for HRA.

  7. Hi Mark

    I think you might want to have a look at some of the current tannoy range for your AXPONA room.

    A lot of products are 30 – 35khz at -6db and are independently tested at that.
    Example http://tannoy.com/residential/#!products_1509

    They have super tweeters aswell to augment HF. I have some modern prestige range tannoys [glenair15], They tear bad recordings apart and make you sit up and realise the qualities of great recordings. The first time I heard one of your recordings on my system I stood up.

    • I’ve always liked Tannoy products, although I haven’t owned any for years.

  8. I am using an Anthem Logic A5- 5 channel amp, that does 120 db signal to noise ratio & an Anthem Logic D2V surround sound processor. This unit has 8 HDMI inputs. Some are audio. I have not used the HDMI connections, as I have used Analog from both my DAC & my Blu-ray player. This system has an advanced room correction system & has an incredible number of inputs & outputs. Check it out on the web.

  9. Hi Dr AIX,

    I saw your comment about the lack of HDMI inputs in digital preamps. Have you had a look at the NAD M51? It has 2 HDMI inputs and is by far the best sounding DAC I have owned so far using the variable output into a power amp.



  10. What about using something like the Krell Foundation Processor TRUE HD/DTS MA 7.1 4K and a bunch of those new JBL powered monitors?

  11. Regarding outputting surround sound for the AXPONA, would it not be easier to use an OPPO-105, which supports either HDMI surround out or more importantly if you cannot find pre-amp with HMDI in, use the ‘105’ as the DAC and the Pre-amp, and connect directly to its 7,1 analog outs (XLRs or RCAs)?

  12. Dear Mark,

    It will be very difficult to find a preamplifer with HDMI input that exceeds or matches 125dB SNR, as per your requirements. The Marantz AV7702 preamplifier has all the HDMI inputs you need, but lack on your demanding SNR for HRA. The loudspeakers could be the Nola Reference Series (ask Mr. Carl Marchisotto) and the Ushers (with diamond tweeters), a very affordable loudspeaker. All of them goes far beyond 40KHz.

  13. Well I suppose the Benchmark Speakers if available is one choice. Using all the same speakers in surround playback was J Gordon Holts ideal. He ran the same Boulder power amps with 5 x Tannoy MKII 10 inch Monitors.
    I considered the Benchmark power amp and speakers but overall I feel active speaker design executed well can outperform passive. You would need to add a subwoofer if you got the Benchmark speakers. I can only recommend one brand in particular that is JL Audio, they also now have an active crossover. I now run Boulder MKI active speakers but they do have a smaller active speaker The Rock MKII Hi-Fi. The German tweeters on these monitors are amazing and very revealing. The Rock’s are imported by a US distributor check this web site: http://www.unityaudioproducts.co.uk/dealers.php. Barry Ober is your man at JLAudio. I’m sure both companies would be willing to support you. This Active setup would be extremely revealing and accurate.

    • I’m thinking more about the Benchmark DAC2 and AHB2 amplifiers. I’ll check out the JL Audio. Thanks

  14. I forgot to add this setup would need good low signal cables and power cords Nordost Heimdall MKII are great.

  15. Hi Mark,

    I’ve talked with you before about the AtmaTec BRASS speakers. 100dB efficiency. Dynamics out the wazoo. Refinement and time accuracy.

    I need you to visit them in Torrance with DAC in tand. My friend is having issues with his DAC, so we need yours to play your high res files.

    • I’m flat to 25k but haven’t measured them above that yet.
      Hope we can pair your recordings and test gear with my speakers soon. Our “AMT on steroids”, covering everything above 500hz, and the power to fill a 300-seat auditorium with audiophile sound, should give your demo the performance it deserves. Make this all private if you wish. I just want to hear your recordings through my speakers.

      • I do as well…things are just crazy busy.

  16. Just realized I made an error in stating , I was connected by analog, as HDMI supports analog. I should have said connected by RCA & XLR connections.

  17. You should definitely use an Oppo BDP-105 and go straight to analog. It has the same Sabre 32 DAC chips as the newer Benchmark but with 8 channels. You can even use the excellent built-in volume control and skip the signal degradation of a pre-amp altogether.

    This is your chance to try a set of the JBL M2. That would really “blow everyone away”! If that’s not possible, contact Bruce Thigpen of Eminent Technology. His speakers go to 50 kHz, have excellent square-wave response, and are eminently affordable. He used to go to trade shows and that’s how I bought my surround set of demo units. He’s also the maker of the Rotary Subwoofer, so if you want to have response down to DC, ask him about that, too.

    • I’ve asked the JBL folks and getting 5 M2s is going to be impossible.

    • Getting down to within half an octave of DC would be adequate. ;o)

      For what it’s worth, that’s a phrase we old Altec-Lansing alumni used to accuse the marketing guys of claiming what their hearing could do.

  18. You seemed quite excited with the JBL M2’s some time back, have you considered them? I think the list of highly dynamic loudspeakers with an extended FR to 40 kHz is rather small…

    • The list is small…especially of speakers that I’ve heard and would like. The JBLs are an option but I asked and getting 5 is impossible.

  19. A way to get full digital 5.1 output would be to use a Vanity Lite board, from Audiopraise, in the Oppo 103. Having looked at the 8 channel analog outputs from the Oppo 105, I would not recommend using them. the noise floor is around 20db higher for the 8 channel outputs than the separate stereo channels. But taking the digital feed from an Oppo 103 using the Vanity lite into three Benchmark DAC2 would keep the signal that you want.

    • I’ll look into this. Sounds very interesting.

  20. I know this is a little bit off topic & somewhat rhetorical, but is the Benchmark amplifier able to power the JBL M2’s? The amp wasn’t to market where the M2’s first were released, I would think that the efficiency and stability of that AAA amp design would be much easier to deal with due to the lack of heat and noise generated by the amps JBL spec’d with originally. I think room acoustics are going to be way more problematic than finding HRA capable loudspeakers.

    • The weakest point of the M2 signal path is the D/A conversion and amplification (built in convertors and Crown amps). At best these amplifiers can deliver an A-weighted SNR of 108 dB. But, the JBL M2 can used with AHB2 power amplifiers and DAC2 D/A converters:

      The M2 processing can be loaded into BSS BLU-800 processors which can be configured with digital outputs. These digital outputs could be routed to Benchmark DAC2 converters and then to the AHB2 amplifiers. Forget about using the analog I/O on the BSS processor (it has the same problems as the converters in the I-Tech amplifiers).

      A stereo setup would require 2 to 4 AHB2 amplifiers (4 if driven bass bridged mono), 2 DAC2 converters, and a BLU-800 processor with digital inputs and outputs. This all seems manageable but moving to a surround system would require a pile more gear.

      As for the room, yes it will be a problem but it’s large enough to give those inside the circle of speakers a very good experience.

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