In my December feature on SoundStage! Access, “Setting Up Speakers and Subwoofers Using Anthem’s STR Preamplifier with ARC Genesis,” I discussed my experience of using the sophisticated Anthem Room Correction Genesis software built into the STR Preamplifier. I explained the many benefits of ARC Genesis, outlined a shortcoming of using ARC Genesis in my own system, and wondered, given that the STR Preamplifier has a built-in phono stage, what it might be like to apply ARC Genesis to my record player’s output. Of course, that last would require digitizing my cartridge’s signal -- sacrilege to the analogophile.
However, this idea of putting a phono signal through the STR’s analog-to-digital converter (ADC), as well as through its built-in digital-to-analog converter (DAC), and comparing those sounds to the unconverted analog signal, seemed an interesting premise for an article. Here’s what I heard.
Setup
I’m more a digital than an analog guy. Not only do I prefer the clean sound of digital, but also its convenience, especially with Roon playback software. That said, I have what might be considered a decent entry-level record player -- a Pro-Ject Debut Carbon Esprit turntable and tonearm and an Ortofon 2M Red cartridge -- and, when the mood strikes, I occasionally sit back and enjoy listening to an LP. I can appreciate the physicality of the medium, and have caught myself watching a record spinning, marveling at the notion that the music is literally stamped into the record’s spiral groove.
For this experiment, I connected the analog outputs and ground post of my Pro-Ject record player respectively to the moving-magnet (MM) inputs and ground post of the Anthem STR Preamplifier ($3999 USD) with AmazonBasics interconnects (RCA). The STR’s balanced analog outputs (XLR) were connected to my two SVS SB-4000 subwoofers, their low-pass filters set to 130Hz at 24dB/octave. The subs’ balanced outputs (XLR) were in turn connected to my custom Marchand Electronics balanced, passive high-pass filter, set to 120Hz at 24dB/octave, and the Marchand’s balanced outputs fed my McIntosh Laboratory MC302 power amp, whose 8-ohm output taps drove a pair of Focal Sopra No1 minimonitors. (I’ve been enjoying the Sopra No1s in my listening room for a while now; a full review will be published on Soundstage! Hi-Fi in a couple of months.) All balanced cables were from Monoprice.
To ease my comparisons of the STR’s phono stage, with and without subjecting its signal to ADC to result in a 32-bit/192kHz digital signal, I used the STR’s unique input-assignment flexibility. In the STR’s Input Setup menu, the user can change not only the input name, but also the input connectors with which the input is associated. The STR also permits the addition of “virtual” inputs in addition to the jacks on its rear panel, with the same configuration flexibility, up to a staggering 30 entries. This means that a single physical input can have different configuration properties. I took advantage of this.
I selected the STR’s default MM phono input with a purely analog pass-through, and turned off this input’s Convert Analog (i.e., to 32/192 digital) option. Then I created a second MM Phono input, named it MM DIGT, and for this input I enabled Convert Analog. Endowing a single physical input with multiple configuration options meant that my turntable, physically connected to only a single physical input, could easily be switched back and forth between MM Phono (pure analog) and MM DIGT (digitized analog).
With Convert Analog enabled, the STR offers Rumble Filter (I left this at the default setting of 35Hz) and seven choices of equalization: RIAA, AES, CCIR, NAB, Capitol LP, Columbia LP, and London LP. There’s also a user-defined Phono EQ option; when this is selected, three adjustable parameters become available for you to create your own EQ: Bass Turnover, Bass Shelf, and 10k De-Emphasis. With Convert Analog disabled, only RIAA equalization is available.
For my MM DIGT virtual input, for which Convert Analog was enabled, I left the default RIAA EQ curve selected, which is what most LPs require. With or without Convert Analog enabled, the STR offers no choices of capacitive loading to match your cartridge.
One question that lingered was whether the STR’s default RIAA EQ was applied in the analog domain for both the pure analog and Convert Analog modes. I asked Blake Alty, product manager at Paradigm, about this. “In the STR series,” he said, “the analog RIAA equalization circuit is used for both the analog direct path and the digital path. That is, the output of the RIAA filter is the input to the ADC. If a different phono emphasis/de-emphasis curve is selected in the phono menu, the DSP applies the difference between the selected equalization and the analog RIAA equalization.”
STR phono stage, pure analog and digitized (no ARC Genesis)
The first thing I listened for when comparing these configurations, without any music playing, was noise. No doubt about it -- in pure analog mode, the noise floor was much lower. Anthem has done a nice job of designing a quiet analog phono stage. Playing LPs, I immediately noticed that the digitized input provided about 6dB more gain, which I ascertained by ear. Even when reducing the volume by 6dB on the MM DIGT input to compensate for the extra gain, its noise floor was still noticeably higher than the MM Phono input’s with nothing playing. However, the noise floor wasn’t too distracting -- the surface noise of most LPs would be significantly higher, which would effectively mask the STR’s noise floor.
The first album I used for critical listening is one of my favorites of all time, and the most expensive I own: Counting Crows’ August and Everything After (two 45rpm LPs, Geffen/Analogue Productions APP 24528-45), which I bought for $90 CDN back when I first got caught up in the vinyl resurgence. Listening to “Omaha,” switching back and forth between my two MM inputs, and adjusting the volume by 6-6.5dB each time, I thought I could hear a subtle difference in their sounds. It wasn’t a difference in frequency response (bass, midrange, treble), dynamics, or soundstage width or depth -- all of these sounded the same through both inputs. But through the digitized input transients sounded slightly sharper, and imaging was subtly more focused. Through the pure analog signal transients were slightly smoother, images more diffuse. When I focused on lead singer Adam Duritz’s voice, the edges that formed the boundaries of the aural image were easier to trace through the MM DIGT input. In fact, every instrument on the stage, from the acoustic guitar to left of center to the accordion off to the right, sounded sharper and imaged more precisely through the MM DIGT input, which is why I preferred it.
Listening to another track I know very well -- “Bad Timing,” from Blue Rodeo’s Five Days in July (LP, WEA 1-143146) -- confirmed what I’d heard with the Counting Crows. I focused on Jim Cuddy’s voice, mixed off to the right, and on Greg Keeler’s backing vocal, imaged just inside and above the right speaker. They sounded slightly sharper, and I could more easily delineate the boundaries between the singers, via MM DIGT compared to MM Phono. I could also hear how some folks might prefer the pure analog sound -- it was smoother, more relaxed. For example, at 1:20 into this track, when Cuddy leans in to the mike to belt out “You’d never do the same thing to me,” the leading edge of “do” can sound edgy or harsh. As I listened to him sing this word through both inputs, it was clear that the pure analog signal smoothed out the leading edge and made it easier and more enjoyable to hear. But that sole example wasn’t enough to sway me to the pure-analog side -- overall, I still preferred the slightly sharper sound and crisper imaging of the MM DIGT input. Digitized analog sounded better to me than pure analog.
STR phono stage, with and without ARC Genesis
As I mentioned in my December 2019 article on setting up speakers and subs using Anthem’s STR Preamplifier and ARC Genesis, one shortcoming I experienced with the room-correction software was the lack of control over the target curve throughout the midrange. I described how I used my Bowers & Wilkins 705 S2 speakers, which have a natural rise in the presence region of the midrange (between 500Hz and 1kHz), and how I could not avoid equalizing away this pleasant aspect of their sound if I also wanted to EQ the treble, which the B&Ws desperately need if they’re not to sound way too bright. As it turned out, the frequency response of the Focal Sopra No1 has a similar midrange characteristic, and while the Sopra’s sound is not nearly as bright, I still faced the same dilemma.
The solution was to use ARC Genesis to apply EQ only up to 350Hz -- that is, to correct only for frequency-response aberrations in the bass. The graph below shows the measured in-room FR, averaged over nine microphone positions, of the Sopra No1s and SVS SB-4000 subwoofers in red and green, as well as the target curve. Where the measured FR changes from red to green is where I turned off the EQ. The Sopra No1’s characteristic midrange rise is clearly visible between 500Hz and 1kHz -- and it’s this rise that I did not want to EQ away.
To evaluate the difference between the system’s bass performance, with and without ARC Genesis, I played some punchy rock: fellow Ottawa native Alanis Morissette’s Jagged Little Pill (LP, Maverick/Reprise, R1 45901), in celebration of the 25th anniversary of this groundbreaking album’s release. Listening to “You Oughta Know” via MM DIGT without ARC Genesis, I heard nothing missing from the lower octaves. With the volume turned up to healthy rock-out levels, the thumping kick drum in the chorus provided satisfying extension and punch through my dual SB-4000s. However, when I then engaged ARC Genesis on MM DIGT and increased the volume a few dB to account for the default attenuation, I could now physically feel what I’d been missing. With that dip in the measured response at around 60Hz now filled in by ARC Genesis, I could easily feel the extra slam and pressure in my chest from the kick drum -- a welcome boost in bass quality! This slight but meaningful improvement in bass response held true with other LPs I played, showing the benefit that can be had when good room correction is judiciously applied to the playback of vinyl.
Conclusions
Anthem’s STR Preamplifier is a versatile device -- a Swiss army knife of a preamp for the audiophile willing to experiment. Here I’ve focused on the STR’s phono stage, and the difference in its sound between a pure analog signal path and digitization of that signal, then with and without Anthem Room Correction Genesis applied to that digitized analog signal. I wasn’t surprised to hear subtle differences between the pure and digitized analog signals, but I was surprised that I preferred the digitized version of my turntable’s output -- it seemed to sharpen images and transients, if at the cost of a slight loss of a smoothness that some listeners might prefer. Ultimately, of course, this is a matter of personal taste. However, when I applied ARC Genesis to the digitized phono signal, it brought another improvement: better bass definition, with more punch and slam.
For me, using Anthem’s STR Preamplifier to digitize the analog output of my modest record player, and then to apply ARC Genesis, is a no-brainer -- it improves the bass response of my system and room. I heard only benefits, no shortcomings. Although the notion of digitizing a turntable’s analog signal might be anathema to you lovers of vinyl, I encourage you to nonetheless give it a try -- you might like the results as much as I do.
. . . Diego Estan
diego@soundstage.com