Accuphase DG-68 Digital Voicing Equalizer Page 2

Happily, I own two microphone stands. I placed one directly behind my customary listening position and aligned the microphone with an imaginary line running between my ear canals. With 15 or so feet of cabling to connect the Accuphase's supplied mike to the DG-68, it was easy to sit to one side and measure the room's acoustic. During the course of the review, I managed to travel back and forth between the DG-68 and my room-left listening position more than 40 times without tripping over the microphone cable.

The result
After I'd created my first curves, I put on Rickie Lee Jones's delicious rendition of the Stones' "Sympathy for the Devil" (Tidal, 16/44.1 FLAC), from her album The Devil You Know. With VC/EQ active, guitar strums sounded more realistic, bass was fuller, and the subtle rattle in the right channel was more easily distinguishable. Tonality was superb, and the slightest change in dynamics or emphasis was easy to hear and savor.


I don't know if the Devil was looking over Schubert's shoulder when he composed Winterreise, his despairing 24-song cycle of love gone bad in wintertime, but mezzo-soprano Joyce DiDonato and accompanist Yannick Nézet-Séguin have recorded one of the most moving accounts in recent memory (24/96 WAV, Erato 528414). When I first listened to the hi-rez files of this recording, I wondered if the piano's lid was closed halfway during the performance, despite a cover photo showing DiDonato singing before a piano opened to full stick. In fact, the piano lid was fully open, but the engineers gave undue prominence to voice. In evening out the bass response, lowering peaks, and filling in some nulls, the DG-68 fleshed out piano accompaniment that had previously sounded undernourished. On a song as moving as "Gefrorne Tränen" ("Frozen Tears"), this fuller support from the piano helped drive Schubert's music and Heine's poetry deeper into the heart.


The DG-68 also enabled me to hear more of Carnegie Hall's natural reverberation whenever DiDonato opened up her sound and to better savor the hall's fabled airy acoustic. It was thrilling to experience how every subtle change in dynamics and tonality deepened the music's impact.

The beauty of Yo-Yo Ma, Edgar Meyer, and Chris Thile's Bach Trios (24/96 WAV, Nonesuch 558933) has made it one of my reviewing staples, but I've long mentally compensated for some notes from Meyer's bass that sounded somewhat faint and others a mite overblown. What a joy, then, to discover that with the DG-68 correcting the room's response, Bach's architecture was given its due, every note perfectly articulated and every pitch clear. It was equally lovely to discover Ma's cello sounding as warm-hearted as I'd ever heard it in my system.


I wouldn't use heart-centered adjectives to describe Yello's "Electrified II" from Toy (24/48 WAV, Polydor 4782160), but on this music, whose electronic pulse could devour a cello, bass, and mandolin in a heartbeat, the DG-68 acquitted itself superbly. It did more than bring the bass home; it surrounded Yello's retro electronics and intentionally overhyped vocals with welcome air and space, bringing unexpected dimensionality to a presentation the visceral awesomeness of which I find hard to resist. There is a lot of well-recorded deep-bass music that I could use in my reviews, but I keep returning to this one as much for its humor as for its wow factor. I'm also delighted to discover that it's now streamable on Tidal in 24/48 MQA FLAC.


I continue to rely on this track for evaluating bass, but I do spend time rummaging about for bass-focused alternatives to this tried-and-true reference, including a recent recording of HK Gruber's Percussion Concertos (24/44.1 WAV, CCR0004) performed by the phenomenal Colin Currie with the BBC Philharmonic. Gruber's use of percussion is more subtle than Yello's, but his mix of vibraphone, drum set, and orchestra in Rough Music is a lovely little test for a sound system. Far more challenging is Copland's Fanfare for the Common Man in Reference Recordings' famed rendition with Eiji Oue and the Minnesota Orchestra (16.44.1 WAV, RR-93). After cranking up the volume as high as my ears allowed, I was astounded to hear the hugest bass drum thwacks I've encountered on record reproduced with no audible distortion.

After recording engineer Peter McGrath told me how much he'd enjoyed listening to Duruflé's organ music on his Wilson XVX loudspeakers, I cued up Thomas Trotter's recent recording, Duruflé: Complete Organ Works from King's College Cambridge (24/192 WAV, KGS0053), and took a selective listen. With VC/EQ engaged, the organ sounded airier and more focused than before. There was more meat to the notes, and it was significantly easier to follow Duruflé's intersecting lines. On this recording, the "Smooth" curve, which purports to take my speakers into account as it tailors sound, seemed more alluring than the "Flat" curve. On other recordings, I preferred the evenness of "Flat" to the plump ripeness and somewhat tubelike warmth of "Smooth." Both clarified bass lines and transformed romantic haze into notes of well-defined pitch.

As winter has morphed to spring and the political landscape has changed, I've found myself less drawn to Alban Berg's apocalyptic Three Pieces for Orchestra, Op.6. But, eager to discover how another frequently referenced recording would sound in a room corrected by the DG-68, I returned to Berg's cacophonous, strangely beautiful 12-tone intersection of cello, bass, brass, and percussion in the version performed by the San Francisco Symphony under Michael Tilson Thomas (24/192 WAV). Nowhere except in a prime orchestra seat in Davies Symphony Hall have I experienced such riveting clarity amidst complexity as I did when listening to this recording through the DG-68. The same held true for the opening minutes of Anna Thorvaldsdóttir's fascinating Metacosmos, on Sono Luminus's superbly engineered Concurrence (24/352.8 WAV, DSL-92237), where the DG-68 laid bare the most subtle shifts in multiple layers of rumbling bass.

There is a downside to such clarity. Take, for example, the rumble of the New York subway system beneath Carnegie Hall, the faint police siren, and the quiet crash of a loosely held Playbill on DiDonato/Nézet-Séguin's live Winterreise (footnote 5); all provide incongruous counterpoint to this saga composed before the Industrial Revolution began to transform the sounds of the German countryside. If there are things on a recording that you don't want to hear—air conditioning, tape hiss, groove noise, a violinist's bow accidentally striking a music stand—beware the DG-68. It's a truth-teller.

Right before I packed up the Accuphase and sent it to John Atkinson for measurement, my friend Peter Schwartzman and I did a final listen with "VC/EQ" active and then bypassed. Neither of us could detect a difference in transparency. Taking another listen after the unit had been boxed up, we detected a slight change. Whether it was related to cables not having time to settle in, I do not know. Regardless, given all the DG-68 can do, I consider some minimal loss in transparency (if there truly was any) with the DG-68 inserted a small price to pay.

Accuphase's Digital Voicing Equalizer is not the sun and the moon and the stars or an electronic stand-in for J.M. Barrie's Peter Pan (footnote 6). If you've got furnishings that suck out percussive snap and make cymbals sound like crushed velvet, the DG-68 probably won't fix it. If your room is improperly treated, the DG-68 can only do so much. Parting the Red Sea is not in its toolbox. But if you worship at the correct altar, which I did once I freed myself from false room-treatment gods, the DG-68 may leave you feeling like you've reached the Promised Land.


The final cut
When I told Demian Martin about the DG-68's manual equalizing functions, he spoke truth. "The potential pitfall with a plaything like that is that you can keep adjusting and adjusting and never get around to listening to music."

My time with the Accuphase DG-68 Digital Voicing Equalizer was among the most enlightening and consequential I've spent with an audio product. Once I discovered how its Auto Voicing function could compensate for the peaks and dips in my room while simultaneously adjusting for loudspeaker response and character, I began to explore how the curves changed as I made one room or system change after another. The DG-68 gave me the knowledge necessary to bring the sound of my room without electronic correction closer to the glories it delivered with Voicing and Equalization functions engaged.

Some will consider the DG-68 anachronistic. When it was first released, in its earliest manifestation (the DG-28), it was something unique. Today, there are other, less expensive ways to achieve similar results—especially with a digital source (footnote 7). But it's hard to imagine those newer methods being as much fun or as simple to use, let alone as foolproof.

I've loved the sound of a lot of the equipment I've reviewed; I've coveted it, to be frank. Yet, I've been able to say goodbye to some truly great gear and move on. I'm finding it harder to bid adieu to the DG-68. Accuphase's Digital Voicing Equalizer has enriched my experience of reproduced music far more than I could have imagined. It is transformational and performs flawlessly, to oft-astounding effect. For those who can afford it, its rich musical dividends may prove essential. Boy, do I hate to see it go.

Footnote 5: Downstairs from Carnegie Hall is Zankel Hall, a much smaller space that hosts pianists and chamber groups. It's a great-sounding hall, but one must get used to the frequent intermittent sounds of the N, W, R, and Q trains that run underneath.—Editor

Footnote 6: My reference is not the book but the 1954 musical in which Mary Martin flew into so many of our hearts.

Footnote 7: Note, too, that I didn't use the DG-68 with its digital inputs. Doing so would avoid two unnecessary conversions and so would, presumably, be even more transparent. The downside is that the digital inputs cannot be used with an analog source. Perhaps we'll explore this in the follow-up review.

Accuphase Laboratory Inc.
US distributor: Axiss Distribution Inc.
17800 South Main St., Ste 109
Gardena CA, 90248
(310) 329-0187

Anton's picture

I would think your room has to be OK for it to be able to produce a decent room curve to begin with.

Your idea of continuing to tweak your room while you have the toy is genius.

It would be cool to have a "mother module" to use to set the room, and then a much less expensive "servant module" or chip that could talk to your DAC that you could then plug in to keep 1-3 curves while allowing the mother ship to continue her sonic journey.

Archimago's picture

Nice to see audiophilia using (at least not afraid of) EQ and finding benefit in "room correction" techniques.

So, basically, from a technical perspective is this performing 2-channel 35-band parametric EQ (settings up to 50kHz)?

Is there any time-domain correction being done when fed with room information (doesn't look like it?)?

teched58's picture

$24,000 seems a̶ ̶l̶o̶t̶ ̶o̶f̶ ̶m̶o̶n̶e̶y̶ very affordable for a 35-band parametric equalizer!

Anton's picture

Wow, what a great addition that would be.

RichT's picture

Something very unexpected here - the flat response curve is incredibly flat, I would estimate -3dB +1dB. This is a flatter response than most professional studios achieve, even the best. It’s totally flat 30Hz to 90Hz, which is absolutely remarkable. This Is very special room.

Kal Rubinson's picture

And not everyone wants flat. ;-)

MatthewT's picture

Perfect is boring.

Kal Rubinson's picture

And, under some conditions, undesirable.

MatthewT's picture

Is the sum of its flaws, and I love them all.

latinaudio's picture

are a necessity. What is certain is that the sound perceiver must be taken into account: the brain. And since no two human beings are alike, it will ALWAYS be necessary to adjust the bass, treble, midrange to each person... in order to have a pleasant experience. Tone controls ARE an unavoidable necessity, and hifi manufacturers builders would be arrogants if they don't accept it. So remember: it´s not only the room, are the persons, specially the owner of the equipment :)

Ortofan's picture

... published in the November 1973 issue of Audio magazine.

It includes a description of the then new Altec 729 Acousta-Voicette one-third octave equalizer and the Altec/HP 8050 real-time analyzer.

Presented is a rationale as to why the corrected frequency response should not be flat over the entire audible range.
The proposed optimum frequency response is flat up to 2kHz, followed by a roll-off above than point at the rate of 3dB/octave.

Kal Rubinson's picture

Good stuff at the time but acoustical science and audio componentry have moved on.........................

Ortofan's picture

... the latest developments in acoustical science (and audio componentry) suggest is ideal?

Kal Rubinson's picture

Toole's book is a good place to start.

Ortofan's picture

... those under the Harman umbrella, agree with Dr. Toole's findings and implement them in their products?

Kal Rubinson's picture

I suspect that all the current AVRs and prepros incorporate them in their EQ options.

zuman's picture

I've been listening seriously and buying good gear for over 40 years, and I firmly believe that the effects of some "tweaks" CAN be measured while we haven't yet discovered how to measure other audible tweak results. However, I also believe that many tweaks are placebos. Is the DG-68 sufficiently sensitive to identify/quantify/adapt to some of the supposed "night-and-day" effects of some of these tweaks?

Anton's picture

Of course, no matter the outcome no minds would be changed.

We are audiophiles, after all. ;-D

pbarach's picture

I wonder how this unit's results would compare to some of the other (much less expensive) room correction systems, e.g., Audyssey, ARC, Trinnov.

Kal Rubinson's picture

Hard to compare correction systems which reside in different hardware.

georgehifi's picture

Love to have this thing, but I would have liked to have heard the comparison of what Rossini Ring/Dac was like from the Accuphase's digital outputs compared to it's own ESS dac (never been a lover of the ESS converters). (was it done???)

Cheers George

AudioBang's picture

Back in the late 90s I bought a Sigtech for $7,300 which, in addition to room EQ, performed time alignment, cancellation of late arriving ceiling, floor and wall reflections out to 50mS, and had the ability to compensate for spectral build up [from room corners, etc].
I owned a pair of Dunlavy Vs at the time, later upgrading to the SC VI.
Since the Dunlavy's are all time-aligned to begin with, as expected, the impulse response did not visually change after a correction filter was applied. I too found it easy to get caught up in jumping from correction filter to correction filter and being distracted from the music. The Dunlavy recommended listening position was against the long wall so the speakers could be placed with a wide listening angle - up to 120 degrees! [per the manual] and obtain the smoothest bass response by eliminating room nulls. I liked mine at about 100 degrees as there was a level of psychoacoustic wonder at hearing a phantom center image with the speakers 12 feet apart while still presenting a reasonably proportioned soundstage. I later learned from the SigTech measurements, that with the listening position against the rear wall, the room buildup in the bass was enormous! A significant contribution in my system that the Sigtech made I felt, was ameliorating the room build up against the rear wall as well as smoothing a 12dB delta from 30hz to 90hz - I suspect from the interactions between the bass drivers positioned at the floor and the top of the cabinet. The low frequency measurements of my speakers from Dunlavy's very large anechoic chamber showed a similar 12dB peak to null although at slightly different frequencies from my room. Also, I recall, not all of that 12dB difference could be flattened as you wouldn't want to add unprecedented gain at high listening levels at the null which could blow the drivers. In a nutshell, in my room, taming the bass [overhang] was a significant factor in arriving at more transparency and I felt that manually treating the room [absorption in my case] for first sidewall reflections worked better than relying on the Sigtech's ability to cancel them out - even though these reflections were eliminated on the filtered impulse response. The measurement capability of these reflections was instrumental in confirming the before and after effects of midrange smearing that was eliminated after applying absorption from first reflections. I was not successful attempting to fix bass problems with corner traps.
The 2khz -3dB/octave rolloff was the recommended default filter. The flat filter sounded dry and sterile and was not pleasurable to listen to although I look back and wonder if part of the reason was that the recommended rolloff starting at 2khz may have masked the sub-par 90s digital in my system [Wadia 270 Transport/27ix DAC]. For what it's worth...

John Atkinson's picture
AudioBang wrote:
Back in the late 90s I bought a Sigtech for $7,300 which, in addition to room EQ, performed time alignment, cancellation of late arriving ceiling, floor and wall reflections out to 50mS, and the ability to compensate for spectral build up [from room corners, etc].

Stereophile's December 1996 review of the SigTech system will be posted to the website the week starting August 9.

John Atkinson
Technical Editor, Stereophile

tonykaz's picture

I recall setting up our Listening Rooms at Esoteric Audio in the 1980s.

We ended up with a Semi-Anechoic type result that needed the Largest Mono Amps pushing thick MH-750 Music Hose Speaker Cabling.

Do our brains re-calibrate room accoustics for us ( to some extent ) ?

I suspect that Room Problems are exasperated by Loudspeakers with too-powerful Bass circuits and no balancing electronic circuits..

B&O make that gigantic Beolab 90 that features built-in Room Correction.

Full Range Loudspeaker Manufacturers should include some sort of Bass management system as an included component. ( Genelec )

Leaving Accoustic Engineering in the hands of purchasing Consumers seems irresponsible.

Accuphase Gear is Georgous

Tony in Venice Florida

AudioBang's picture

I concur that our brains recalibrate room acoustics for us - to some extent....
Interestingly, per MF and other Stereophile reviews on the ISO Acoustics speaker isolators, I tried three sets on my Dunlavy SC VIs [650 lbs each] and they completely altered the bass. On the one hand, I agree with one of the reviewer's comments that they were "different" and on the other, the bass overhang that I am used to [assuming] from room modes, was reduced an order of magnitude as if "where did it all go?" But the transparency, depth and expanded soundstaging these footers offered was unexpected and unprecedented. I'd take these results 10X over any EQ solution. Because the rebuilt 4-way crossovers reside outside the speaker, while I was contemplating trialing the footers, I had disconnected the bass completely out of the picture to test whether the vibrational bass coupling to the floor made any difference to the midrange/treble. I didn't hear any difference. But after installing the footers everything transformed at the magnitude that MF stated in his review. I can only assume that even with just midrange and tweeter operating, something vibrationally is happening to/within the 650lb cabinet causing blurring to occur. My brain can not connect how that happens. BTW Stereophile, thanks for your value-add here. This was one of the most profound improvements I've experienced.

tonykaz's picture

Can we hear from the Loudspeaker Manufacturer on these devices.? Why don't they include these with every speaker?

I probably consider them to be like Engine Mounts for a vibratingly harsh Car, Truck, Boat Engines.

NoiseVibrationHarshness is a science, we should be able to explain these phenomenons and bring about consistant effects/affects.

In the 1980s I sold large quantities of Audio related do-dads, Audiophiles love to tinker around with this stuff.

Tony in Venice Florida

Kal Rubinson's picture

Can we hear from the Loudspeaker Manufacturer on these devices.? Why don't they include these with every speaker?

Good questions and there are a couple of speakers with them on their way to market The general answer is that it will increase the price of the speaker and manufacturers have to compete on price in the real world.

It evokes the memory of an amp manufacturer who told me that I could not realize the full potential of his product without a particular after-market power cord. I was surprised at that and asked why he would not just include it. He replied that it was a matter of price. I bought one anyway (who would not want his new amp to sound its best) but I found it was absolutely not audibly different from the stock cord. He should not have opened his mouth.

Ortofan's picture

... is including shock-mount feet.
Speaker prices range from $1,850 to $4,250 each.

Kal Rubinson's picture

PSB, too.

tonykaz's picture

Good Better Best has been a Sales Standard in all sorts of Product types..

I'd expect better from the Full Range Transducer System manufacturers, just as we've come to expect ( and rely on ) Stereophile Reviewing and Editorial Standards.


Audiophiles are typically DIY kinds of folks.

I'm a Fan of Meridian type of Music Systems approach from Manufacturers. I can enjoy a high performance designed full System from one Company.

Still Tweaking one's music systems can be a nice little distraction from the World problems crushing our shoulders.

Big Fat Stiff Power Cords are visually impressive, you could say "those power cords alone cost Thou$$$$$$and$$$ of Dollars!! ( even toss a handful of hundred dollar bills on the floor behind the speakers ( to show off even more )

Audio stuff can still be fun! I think

Tony in Venice Florida

tonykaz's picture

I just heard that the NY Auto Show is cancelled.!!!

We're not out of this China Plague yet

Tony in Venice Florida where masks are still optional

Kal Rubinson's picture

But what about the NY Audio Show?

tonykaz's picture

It seems that we are entering a new phase of China Pandemic hysteria with this Fresh Strain that can be understood but isn't..

So, we might usefully predict that Big Shows will set the pace for all the little Shows like Audio and/or things like Tool Shows.

CDC is predicting the New Strain will take the rest of this year to run it's course ( in USA that has less than 100% Vaccinations depth ).

Global Vaccination percentages have barely scratched the surface so we are a looooooonnnnnnnngggggg way from Herd Immunity!

Will it predictably take the Standard 3 to 4 years for this blight to run it's course ???

Will the politicians and media continue to foster Health condition Panic among the innocent polis ?

I have the feeling that Streaming and DACs like the dcs Bartok will have overwhelmed HighEnd Audio by the time this Virus is tamed.

It's time to sell off my Koetsu & Vinyl collections

Tony in Venice Florida

AudioBang's picture

I think you would be a very cool neighbor to have Tony :)
I enjoy your industry stories and commentaries from your experiences.