Integrated Amp Reviews

In 1989, I bought my second pair of Rogers LS3/5a's from a guy on Staten Island who had them hooked up to a Musical Fidelity A1 integrated amplifier. After playing the speakers for me, he began removing his zip-cord speaker cables and paused to show me how, at the amplifier end, his red-plastic Pomona Electronics banana plugs had partially melted from the A1's heat. We both laughed.

After it first appeared in 1985, the A1 quickly became famous for its hot top plate. The top plate got as hot as it did because it was used as a heatsink for the output transistors, which were biased highly into class-A. The A1's hot top made tabloid headlines, but for me it was its bold, sinewy, un-transistory sound and timeless, sharply drawn styling that distinguished it from cooler running Brit-fi competitors such as Audiolab's 8000A, Creek's 4040, A&R Cambridge's A60, and NAD's 3020.

Despite the Daily Mirror headlines, it was the A1's all-natural sonics—not its top-plate temperature—that made it an instant classic.

Now it's back, priced at $1779, looking and feeling cooler than before.

As I type this, it is 85°F in my room, and I just held my palm 1" from the A1's chassis-top heatsink and could barely feel heat rising up—maybe none at all. Using a digital oven thermometer, I measured the chassis-top temperature at 140.1°F (60°C): too warm for toddler fingers but 5° cooler than the original's design-specified heatsink temperature of 65°Celsius.

History
My introduction to Musical Fidelity's tuneful aesthetic began in the late 1970s, when Anthony Michaelson ran a company called Michaelson & Austin, which was selling EL34 tube amplifiers designed by the first audio designer I christened a "Tall Wizard," my soon-to-be friend and Triode Mafia brother Tim de Paravicini. Tim's design for the TVA-10 was a testament to our shared belief that in any properly designed audio amplifier, tubes and transistors sound alike. I believe Tim's design for Musical Fidelity's A1 proved that point.

When Musical Fidelity founder Anthony Michaelson retired in 2018, he sold the brand and its intellectual property to Austria-based Heinz Lichtenegger of Pro-Ject and its parent company, Audio Tuning. The relationship between Musical Fidelity and Audio Turning goes back decades.

Description
I asked PR wonderperson Wendy Knowles (who arranged this review) if someone could verify that the A1 I'm reviewing bears more than a cosmetic resemblance to the Tim de Paravicini–designed original. She asked Heinz, who replied, "Simon Quarry, our designer, 100% respected Tim's design, only changing components to enhance reliability."

To that end, Musical Fidelity's new A1 puts Tim's original circuits in a wider, thicker chassis, with more heatsink area, a bigger transformer and power supply, better circuit boards, more capacitance, closer tolerance, parts rated for higher temperature, beefier binding posts, more ventilation holes on the sides, and more line-level inputs (5). Plus, Tape Out (fixed) and Pre Out (variable). All RCA. No balanced inputs or outputs. The chassis measures 17.3" wide, 2.7" high, and 11.1" deep. The A1's output stage is class-AB, rated to deliver 25 pure class-A watts into 8 ohms. Its maximum voltage is specified as 42.5V peak–peak. The damping factor is specified as 150, which suggests an output impedance of about 0.05 ohms. The specified RIAA response accuracy is specified as ±1dB.

The A1's blue-lettered, timelessly styled, touch screen–free front panel pleased me more each time I looked at it. The volume control dial felt solidly anchored and durable as it twisted the shaft of an ALPS RK Series remote-powered volume control. Speaking of remote: The remote control—none was provided with the original A1—is a 4" long, solid aluminum thing with three rectangular, rubber-covered buttons: Vol+, Vol–, and Mute. Like the A1 itself, it looks timeless.

Between the Volume dial and the selector dial—"Phono," "CD," "Tuner," "Tape," "Aux 1," "Aux 2"—lies an unlit Normal/Direct button that also was not on the original. "With this switch, you can totally bypass the gain block before the volume control," Musical Fidelity says, "resulting in roughly 10dB less gain. This feature proves particularly advantageous when working with modern or high-output digital sources, enabling fine tuning the range of your volume potentiometer and accommodating sensitive loudspeakers."

According to Musical Fidelity's website, "The new A1 has received an updated transformer from shared (in 1985 original) to a more efficient dual-mono [transformer] with split rail windings, resulting in amp stages that are supplied by fully independent left and right power supplies. Each amplifier now has double the original's supply capacity resulting in reduced ripple and noise." Elsewhere, it says, "The A1 employs a discrete current-mode input stage for lowest noise with MC and MM cartridges. A low-noise current-to-voltage conversion stage is used for further amplification and RIAA equalization. Automatic input impedance matching for the selected MC input, along with increased gain, increases the versatility of the A1's phono stage." According to the owner's manual, the moving coil phono input is best suited for cartridges outputting no less than 100µV and no more than 800µV.

I asked Heinz what that current-to-voltage stuff means. "The first stage MM and MC cartridges see is a voltage-to-current converter, which also acts as an amplifier," he responded. "Afterwards, as described on our website, a low-noise current-to-voltage conversion stage is used for further amplification and RIAA equalization.

"In total, a significant bulk of the amplification is done" in current mode. That means lower noise than if pure voltage amplification was used throughout. "This is our very unique design that brings a lot of sonic advantages." One result of this approach is to effectively load the MM circuit with about 50k ohms of resistance, Heinz said.

"Then, for the MC stage, we switch the transistor's emitter resistor to a lower one! It is important to know that the amplification factor on the discrete input stage is dependent on a transistor's emitter resistor! So by switching that resistor, we increase the gain in MC mode (to 60dB) while subsequently also automatically reducing the input resistance to match MC cartridges. This is a very different approach compared to typical MC stages. It works out to just about 1k ohm input resistance. "Doing it this way gets us the benefits of a very clean and tidy MC Phono Stage design, plus all the current-mode benefits."

Playing records
I could have written this review after playing just one record: Festivals of the Himalayas (Nonesuch Explorer Series LP H-72065), which was recorded on site by David Lewiston, produced by Teresa Sterne, and mastered by Robert Ludwig at Sterling Sound. I dropped the needle, and my speakers lit up like a movie screen. The room came alive with sound.

Listening with Nagaoka's MP-200 moving Permalloy cartridge into the MF A1's MM phono input, I found myself grinning at the volume and extensive detail of the projected soundspace. It was like viewing a real place through a wide-angle lens.

In single-mike field recordings made by professionals, where the performance is unedited and the tape is unprocessed, the sheer dimensionality of the reproduction can be transporting. Through the A1's MM phono stage, the three-dimensional space of the Himalayan festival appeared as an infinitely large dome, with drums and noisemakers, singing, and diverse humanity, coming in from all directions. I could hear from the ground to the sky and sense something like a horizon or perimeter where the microphones ran out of sensitivity. Tone and texture were super vivid, supporting the illusion of being there in the midst of a crowd, in an Indian village.

I have owned, repaired, or reviewed legions of integrated amplifiers, including some very expensive ones, but none with a moving magnet phono stage that impressed me more than the A1's did as it amplified the output of the Nagaoka MP-200.

I tested the A1's MC input with Dynavector's XX2 moving coil cartridge. Its 0.28mV (280µV) output and 6 ohm internal impedance seemed like it might match up well with the A1's "self-adjusting" MC input. I know and love this cartridge; I've used it with every kind of SUT (including Dynavector's own SUP-200), with JFET headamps, and with a range of transimpedance step-ups including Sutherland Engineering's SUTZ and Little Loco and Hagerman Audio Labs' Piccolo Zero. Through the A1's MC input, the XX2 sounded as quick-afoot as it always does when it is happy with the load it is seeing. Transparency was reduced relative to Sutherland's SUTZ transimpedance headamp, but through the A1 the XX2 sounded bolder and bass-punchier than it did with SUTZ.

I tested how Tim's unusual MC input would handle the 40 ohm Denon DL-103 MC cartridge. I found that it played churchlike, but not hallelujah level. Voices and instruments were nowhere near as clear and certain as they were with my current favorite Hana MC, the Umami Blue. So I tried the Umami Blue.

With the A1, the Umami Blue's 0.4mV output and 8 ohm internal impedance imparted a crisp, gain-is-just-right vibe to every disc I tried. The A1's MC input really lit up and clicked with the Umami Blue.

Musical Fidelity's A1 never sounded more exquisitely detailed or transparent than it did playing "Moonchild" from King Crimson's In the Court of the Crimson King (Atlantic LP SD 19155). I'm sure most of you know this record; I wish you could have heard how tone perfect and Windex clear this track sounded coming from my Falcon speakers. Again, the soundspace was enormous, the presentation bold and highly visual. I began to sense a pattern.