Low Stock Warning - Due to very high demand, we expect shortages of some products. Place your order today.

0

Your Cart is Empty

LA4 - Lab Report - John Atkinson, Stereophile

by Benchmark Media Systems December 24, 2019 2 min read

LA4 - Lab Report - John Atkinson, Stereophile

"Benchmark's LA4 is the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I have encountered."

- John Atkinson

"I measured the Benchmark LA4's performance with my Audio Precision SYS2722 system (see the January 2008 "As We See It")."

Audio Precision AP2722

Frequency Response

"The preamplifier's frequency response in both balanced and unbalanced modes was flat from 10Hz to 200kHz both into the high 100k ohm load  and into 600 ohms was taken with the LA4's volume control at its maximum setting; both the response and the superb channel matching were identical at lower settings of the control."

Gain Accuracy

"The gain for the balanced inputs to the balanced output with the volume control set to "+15" was exactly 15dB, and reducing the control to "0.0" resulted in a gain of 0dB—ie, the output voltage was the same as the input voltage."

Benchmark LA4 Rear Panel

Input and Output Impedance

"The LA4's balanced input impedance was both usefully high and higher than the specified >50k ohms, measuring 80k ohms (40k ohms per phase) at 20Hz and 1kHz and still 75k ohms at 20kHz."

"The balanced output impedance was a low 61.5 ohms, the unbalanced impedance 201 ohms, both values consistent across the audio band."

Channel Separation

"Channel separation was simply superb, at >140dB, R–L, and >132dB, R–L, below 2kHz, respectively decreasing to 130dB and 112dB at 20kHz."

"The superb separation measurement is a testament to excellent circuit-board layout, something I have commented on before with Benchmark D/A processors."

Noise

"From balanced inputs to balanced output, the Benchmark preamp offered extremely low noise, with virtually no power-supply–related spuriae in its output."

Headroom

"The LA4's balanced output doesn't clip (ie, when the THD+N reaches 1%) until a very high 24V."

THD

"I looked at the spectrum of the distortion at a similarly high output level; while the second and third harmonics can be seen, these are still at astonishingly low levels: each harmonic is at or below –120dB (0.0001%) and is close to the residual level of these harmonics in my Audio Precision SYS2722's signal generator."

Benchmark LA4 THD FFT - John Atkinson, Stereophile Magazine

IMD

"Tested for intermodulation distortion in balanced mode with an equal mix of 19 and 20kHz tones at peak level of 5V, the second-order difference product at 1kHz was effectively absent, and the higher-order products all lay at or below –114dB."

Conclusion

"Benchmark's LA4 is the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I have encountered."

- John Atkinson, Stereophile Magazine

The above is just a brief summary of John Atkinson's independent lab tests. Please follow the link below to read his entire test report which includes 9 high-resolution test plots (including the two shown above).

Read the entire review here →



Also in Reviews

AHB2 Award - "Legendary Performance Award 2020" - EnjoytheMusic.com
AHB2 Award - "Legendary Performance Award 2020" - EnjoytheMusic.com

by Benchmark Media Systems October 15, 2020 1 min read

"This little unit will change the way you look and listen to amplifiers."

"My first taste of this remarkable new amplifier came earlier this year in April at Chicago's AXPONA where I discovered it driving a newly redesigned Studio Electric Pasadena loudspeaker, also bearing the Benchmark trademark. Now called the SMS1, the Pasadena's crossover had been reworked by Benchmark, upgraded with very low tolerance components, and the new look, more in line with the look of the rest of the Benchmark product line up, had been adopted."

"The subsequent sound in this room was one of the most musically engaging I encountered at this year's event, a remarkable result considering its modest overall system price of just over $7000, sans source."

Greg Weaver, EnjoythMusic.com

Read More
DAC3 - "A+ Recommended Component" - Stereophile 2020
DAC3 - "A+ Recommended Component" - Stereophile 2020

by Benchmark Media Systems September 30, 2020 2 min read

Jim Austin wrote, "The DAC3 was all about depths, in several respects . . . I heard deeper into the music."

The concise conclusion to John Atkinson's Measurements sidebar: "All I can say is 'Wow!'"

In a Follow-Up, Jim Austin wrote of using the Benchmark processor with the same company's AHB2 power amp—a combination of high source output voltage and modest amplifier gain that he describes as "optimal for minimizing noise and distortion"—and reported hearing "richer and more interesting" reproduction of very subtle details.

- Stereophile Magazine

"Class A+" is Stereophile's highest award for Digital Processors

Read More
LA4 - "Class A Recommended Preamplifier" - Stereophile 2020
LA4 - "Class A Recommended Preamplifier" - Stereophile 2020

by Benchmark Media Systems September 30, 2020 1 min read

"Benchmark's LA4 is the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I have encountered."

- John Atkinson, Stereophile

"The LA4 is probably the most transparent and revealing audio component I've ever used. It does not seem to leave any fingerprints on the sound."

- Kalman Rubinson, Stereophile

"Class A" is Stereophile's highest award for preamplifiers.

Read More