Impressed by all the online reviews and claims about the differences between the Ultra and Classic series, I’ve decided to purchase an expansion card for my Ultra. This card features converters from the “Classic” series era and is based on the AD1861 DAC as used in E4X Turbo (this makes perfect sense as this card was originally designed for E4X Turbo). The Emulator Ultra series and the “Classic” represent two distinct approaches to digital-to-analog conversion, each with unique design philosophies and hardware configurations tailored to their era and application.
Shown in image above, the Emulator Ultra series features a Cirrus Logic CS4329 20-bit DAC with differential outputs. This DAC is based on the Sigma-Delta conversion architecture, a method known for its high resolution and excellent noise shaping capabilities. This approach reduces quantization noise in the audible range, making it ideal for achieving clean and accurate audio reproduction. The Ultra series further enhances its balanced output design by incorporating two OP275 op-amps per channel to generate balanced signals. The OP275 op-amps are well-regarded for their low noise and high fidelity, ensuring that the balanced outputs maintain the integrity of the signal. This setup aligns with professional audio standards, where balanced outputs are preferred for their ability to minimize noise and interference, especially in studio environments with long cable runs.
In contrast, the Emulator 4X “Classic” employs an 18-bit PCM DAC from Analog Devices, specifically the AD1861 (shown in the image above). The PCM conversion approach relies on precision resistor ladders to directly convert digital signals to analog. While this design is less common in modern equipment due to the rise of Sigma-Delta converters, it has its own set of strengths. PCM DACs like the AD1861 are often praised for their natural and musical sound characteristics, offering a straightforward signal path with minimal processing. The 18-bit resolution reflects the technological standards of its time, and although it may lack the extended resolution of modern 20-bit or 24-bit systems, it was more than sufficient for producing high-quality audio during its era. In summary, the choice of converters and supporting components reflects the technological advancements and priorities of the time.
Being such different converters (one PCM, other Sigma Delta) I’ve decided to undertake a small task: browsing the web to find out what people are saying about the difference in sound between the Emulator 4X (Classic) and Emulator 4 Ultra series. The overall “repeat phrase” seems to be:
“The converters on the E4 Classics are better than the Ultras; they sound warmer, and the bass is rounder. Also, the Classic features an R2R DAC, while the Ultra does not. R2R generally means more punch, better dynamics, and an overall warmer sound, with more non-linearity and harmonics in the lower end.”
And now that I have finally purchased this expansion card and completed all of the analysis and tests I can tell you one thing: I wish the above quote was correct, but unfortunately it is not. 🙁
As now I own an Emulator Ultra with the output expansion card PC511 (rev A) – which, as mentioned earlier, uses the same converters as Emulator “Classic”. This means I have access to both generations of converters—the PCM and the Delta converter. I decided to test them both. I really hoped they will sound different, giving me access to two different sonic colors from two different generations of Emulators only to find out they sound exactly identical. The harmonics are the same, the dynamics are identical, stereo separation is the same, etc…
The only difference that was found – Ultra has a better anti-aliasing filter, which technically makes it “warmer” which is a bit amusing as people say it’s the other way round (remember “repeat phrase” quote three sections above?). However, in practice, this makes no difference whatsoever because we’re dealing with frequencies above 22 kHz. In the Emulator Classic, these frequencies are mirrored above 22 kHz, while in the Ultra, they are properly cut as we will show in spectral analyzer below. Now, let’s listen to some examples recorded through each of these converters. Output from Emulator was recorded into RME UCXII at 48 kHz.
Low frequency
The bass sounds exactly the same on both converters. The harmonics are identical when listening on my Neumann KH120A speakers and Beyerdynamics DT880’s headphones. This is also confirmed by the spectrogram shown below as it covers the important bass range from 10 Hz to 1 kHz – the first part of the recording was made on the Ultra and the second half recorded on the Classic, both files normalized and then joined into one for easier analysis side by side. For anyone who has doubts about the accuracy of this information, feel free to download the provided source audios and analyze the data for yourself.
Emulator Ultra: Bass-ultra.wav
Emulator Classic: Bass-4xt.wav
High frequency
Now, let’s take a look at the high frequencies. One important thing to keep in mind is that the source sample was 44 kHz. This means that anything appearing on the spectrogram above 22 kHz should absolutely NOT be there! I deliberately recorded the audio at 48 kHz to highlight the aliasing issue with the Emulator “Classic.”
Up to 22 kHz, everything is absolutely identical. Every individual harmonic or standout point present on the Emulator Classic is also present on the Ultra. The spectrogram below contains the first part of the recording made on the Ultra and the second half recorded on the “Classic.”
Emulator Ultra: Cymball-ultra.wav
Emulator Classic: Cymball-4xt.wav
So where’s the difference?
We have seen thus far that in 0-22kHz range there is no difference in sound and spectra whatsoever. Some may argue, “Perhaps the difference lies not in the frequency range but in subtle dynamics and stereo separation that no spectrum analyzer can capture.” Fair enough. Here is a stereo beat with plenty of dynamics. Can you identify which of the two recordings is from the Emulator Ultra and which is from the Emulator “Classic”?
StereobeatA.wav
StereobeatB.wav
Let me help you: No one can tell the two apart. 🙂
Conclusion
The most important takeaway from all this is simple: whenever someone claims i.e. that an A converter is “superior” to a B, always ask them for actual audio evidence, rather than their impressions and thoughts. This will certainly save you a lot of money. In my case, the expansion wasn’t overly costly, and it might even encourage me to use my Emulator for more serious work. Overall, it turned out to be a positive experience and my Emulator with extra 8 outs has technically increased in value. So nothing was lost in the end.
