Note that this is a discontinued product. You may want to visit the brand's page here to browse their newer products.
What reviewers think
Bloggers and YouTubers have tried this product—so we've summarized their strongest opinions below. Links to full reviews follow.
Product Strengths
- Overall performance is excellent, with a well-detailed and clean midrange, beautiful sparkle to the high frequencies, and big bass sounds
- Low noise floor makes for an amazing listening experience
- Has the ability to play all genres of music well
- Offers a dynamic, vivid, and holographic soundstage that is open, expressive, and supremely dynamic
- Very neat and pleasant to use, everything works as intended
Product Considerations
- RCA inputs are of average quality
- Not ideal as a platform for upgrading, or to drive difficult loudspeaker loads at high volumes
- Gives a three-minute time-out between power-ups, and a 50 second countdown from cold
Comparisons (according to reviewers)
- Vs Naim Uniti Star: The vocal timbre may be a little thin compared to the Naim Uniti Star, but there's a clearer focus on detail with the I/50
- Vs Octave V70 SE: The I/50 isn't as neutral as the Octave V70 SE, nor as powerful, but it still has enough fullness to make instruments sound really convincing
- Vs Leben CS-300X or CS-600X amplifiers: The I/50 sound is not as saturated as with the Leben CS-300X or CS-600X amplifiers, working as headphone amplifiers, but it is very good
Takeaway: The Audio Research I/50 is a great all-in-one tube amplifier with a simple approach to tubes, that is a blend of the harmonics of a tube with a more dynamic—snappier—lower coloration of solid state. It is an amplifier that anyone could live with and enjoy because it combines good looks and a sound that is easy to like and extremely easy to live with.
All
I/50
reviews
Manufacturer details
- Power Output: 50 watts continuous from 20Hz to 20kHz
- Power Bandwidth (-3dB points): 10Hz to 22kHz
- Frequency Response (-3dB points at 1 watt): 7Hz to 30kHz
- Input Sensitivity: 1.25V RMS for rated output
- Input Impedance: 100K ohms Balanced, 48K ohms Single Ended
- Output Polarity: Non-inverting. Balanced input pin 2+ (IEC-268)
- Inputs: 4 balanced, 4 single-ended
- Output Taps: 8 ohms, 4 ohms
- Power Requirements: 105-130VAC 60Hz (210-250VAC 50Hz) 252 watts at rated output
- Tube Required: 2 matched pairs 6550WE; 3 x 6922 (1 input, 2 driver)
- Dimensions: Width 16.5" (42 cm) Height 7.25" (18 cm) Depth 13.5" (34 cm)
- Weight: 40 lbs (18.1 kg); 51 lbs (23.1kg) shipping weight
Brand highlights
Taking a step back to look at reviewers' thoughts of the brand's entire lineup—not just this product—what stands out most is the following:
- Audio Research employs a design philosophy of cascading technological advancements, with innovations first appearing in their top-tier Reference series, then trickling down to the more accessible Foundation series.
- A unique aspect of Audio Research's digital products is their use of separate, optimized digital pathways for PCM and DSD signals, ensuring the highest quality conversion for each format.
- The use of vacuum tubes in the analog output stage is a core characteristic, contributing to a distinctive midrange fluidity and timbral accuracy designed to minimize the harshness often associated with digital audio.
- While embracing modern features like user-selectable upsampling and digital filters, Audio Research prioritizes sonic balance and accuracy, aiming for a sound that is neither overly warm nor bright, but fundamentally "right."
Select products
I/50 Integrated Amplifier
- Positioning: The entry-level integrated amplifier in the Audio Research lineup.
- Description: Offers a compact design with a powerful all-tube amplification circuit, making it ideal for small to medium-sized rooms. Features optional DAC and phono modules, providing flexibility for various audio sources, unlike the more specialized power amplifiers in the lineup.
VT80 SE Stereo Amplifier
- Positioning: A mid-range stereo amplifier, offering a balance between performance and affordability.
- Description: Uses KT150 tubes for a robust output, suitable for diverse speaker setups. Provides a fully balanced design, unlike the I/50, and is more powerful.
Reference 160S Stereo Power Amplifier
- Positioning: A premium stereo amplifier, designed for serious audiophiles.
- Description: With its dual GhostMeters and advanced auto-bias technology, provides superior soundstage and detail. Offers more power and flexibility than the 80S.
Reference 330M Monoblock Power Amplifier
- Positioning: The flagship monoblock amplifier, representing the pinnacle of Audio Research's engineering.
- Description: Combines groundbreaking technology with an all-tube signal path, offering unmatched control and dynamic range. Surpasses the 160M MKII in power and sophistication, making it the ultimate choice for those with no budget constraints and a desire for the best possible sound.
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Used
Audio Research
What if you spend more?
Features Matched tubes: 2A3 x 2/4 (OR 45 x 2/4, OR 50 x 2/4, OR 300B x 2/4) – 6SN7 x 2 – 5V4 x 2 – 6X5 x 1 Inputs: 3 line inputs Signal input: 400 mV for max power Outputs: 1.6W / Channel with one 45 — 3.6W / Channel with two 45 3.5W / Channel with one 2A3 — 7W/ Channel with two 2A3 5W / Channel with one 50 — 10W with two 50 7W / Channel with one 300B — 14W / Channel with two 300B 9W with one 300B XLS / Channel — 18W / Channel with two 300B XLS Outputs impedance: 4 – 8 ohm (other impedance available upon request) Frequency range: 15 – 35.000 Hz Power Supply: 100/115/230/240 VAC – 50/60Hz. Other voltage are available upon request
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Product Strengths
- A variety of tubes can be used (45, 2A3, PX4, PX25, 300B, or 300B XLS) to produce different power outputs (1.5 to 22wpc)
- It can operate in single-ended (SE) or parallel single-ended (parallel SE) mode
- It is very adaptable—allowing for changes to input tubes and 5AR4 rectifiers to alter the amp's sound
- Built-in bias meters and pots allow for re-biasing when changing tubes
Product Considerations
- The right speaker load (high output impedance) is needed to perform optimally
- Single-ended amps shun negative feedback, which would lower their output resistance
- Speakers not well-suited for high output impedance amps may experience premature bass roll-off and a rising presence response
Takeaway: The TK2A3/300PSES-i Ref amplifier offers a lot of flexibility for tube rolling and sound customization. It is well-suited for high-efficiency speakers.
Video review
Our take on the brand
The SE300B Mono Amplifier is... an all-tube power amplifier employing the famous classic 300B filamentary triode in single-ended operation mode for an output of up to 10 watts into a 4, 8 or 16 ohm loudspeaker load. The 300B power tube is excited by an extraordinary single-stage driver employing two CV2382/EL822 power pentodes operated in triode mode with high idle current and works into a C-core output transformer built in-house to the highest possible standards so as to ensure ultimate performance. The amplifier is built with meticulous hand construction using our proven point-to-point wiring techniques whereas much care has been taken in arranging each aspect of the internal construction to ensure low noise performance, ease of service and the highest reliability for many years to come.
Our summary
Product Strengths
- Pure sound, free of coloration while retaining musical detail, allows a graceful and effortless listening experience
- Natural and tangible sound due to accurate reproduction of details, creates a believable presentation
- Solid and controlled bass performance, unusual for a 300B single-ended triode amplifier
- Excellent sense of touch and tactile sound, making instruments like plucked strings and bowed violins sound very convincing
- Wide and deep soundstage with good 'air', providing a transparent and 'hear-through' sound, especially with complex music
Product Considerations
- Careful matching with partnering equipment is required, especially speakers with high efficiency
- Relatively low overall gain requires a source with a high output voltage
- Output transformer links need to be correctly set for speaker impedance, requiring dealer assistance
- Some reviewers found the top end sounding a bit rolled off before use of appropriate high efficiency speakers and source gain settings
- Changing the EL803S driver valves requires carefully matched pairs supplied by Thöress
Comparisons (according to reviewers)
- Vs Shindo Haut-Brion/Corton-Charlemagne, Thöress has more treble extension and transparency, Shindo has better upper-bass/lower-midrange substance and body—and more drive
Takeaway: The Thöress SE-300B offers a supremely musical and detailed listening experience with a focus on accuracy and sonic purity. When paired with the right speakers, this amplifier could be an excellent choice to bring out the best in music.
Video review
Our take on the brand
One of the finest parallel single ended 300B tube amplifier made by Fezz Audio. It provides openness and spatial sound. Powerful, sublime, very involving and uniqe to itself. Fezz Audio Lybra gives you the best sounding experience you can get from the 300B tubes.
Our summary
Product Strengths
- Delivers an incredibly rich, flavorful midrange and a sweet, relaxed treble
- Has a more sophisticated presentation than the utilitarian bent-metal chassis sported by most integrated tube amps on the market, and the smooth lines of the chassis help the amp stand out from the crowd
- Has a clever tube cage design with a clear Plexiglass front panel that delivers an unobstructed view of the tubes and is easy to install and remove
- Is seriously quiet, and there was effectively zero noise through any of the speakers
Product Considerations
- Can sound wildly different, depending on the impedance of the speakers
- The four slightly squishy feet underneath the amp may cause stains
- The power switch is on the rear of the chassis, which may be problematic if installing the amp in a cabinet with limited access
- Needs a good 20 minutes to warm up, and on initial startup, the amp sounded a bit thin, bright, and constipated, but after one album, it opened right up
- Limited power output (15Wpc) may not be sufficient for all speakers or listening preferences, especially when wanting to play music very loud
Takeaway: The Fezz Audio Lybra 300B is a well-designed tube amplifier that delivers a rich and flavorful sound. It can bring out the best in your speakers, offering clarity and great sound.
Video review
Our take on the brand
The MC2301 is the first McIntosh vacuum tube amplifier to use our Quad Balanced design. This design cancels virtually all noise and distortion in the audio signal. As a result, even when amplified to high levels the signal is effectively free of any distortion. Our fuse-less short-circuit protection circuit Sentry Monitor™ disengages the output stage before current exceeds safe operating levels and then resets automatically. Inputs for balanced and unbalanced cables are available to provide flexibility in connecting the rest of your audio system.
Our summary
Product Strengths
- Fast response, with detail, and a warm tube sound
- Picks up detail with speed when playing Hi-Res digital content
Product Considerations
- Lacks sound stage depth/width, power, and feel compared to the reference system (vintage MC275 amplifiers)
- Super tweeters seemed to be sleeping—as if there was no data provided at that frequency
- Lacks a big window of performance, energy, and feel, providing a smaller window of performance albeit nice with a tube-like sound
- Bass with the MC2301s was starving when compared to the 275's
Comparisons (according to reviewers)
- Vs vintage 1960s MC275: MC2301 lacks sound stage depth/width, power, and feel, a full rich lush enveloping sound, and energy that stirs emotion
- Vs later generations of the MC275: MC2301 would be superior
Takeaway: If you don't have access to vintage MC275s, the MC2301 could be a good option, providing a tube-like sound with detail and speed. McIntosh should look back and reconsider past designs.
Video review
Our take on the brand
What competes at this price?
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Our Summary
Product Strengths
- More musically convincing, more detailed, more harmonious, more linear, and more transparent than any other similar EL34 design at any price.
- Piano music is most perfect and quick, with purity of tone and tambour with proper richness and speed.
- Silent with totally black backgrounds, micro and macro dynamics are unrestricted and natural.
- Reveals its glory quickly due to its transparency.
- Excellent fit and finish and it worked right out of the box.
Product Considerations
- Thick or lean sounding cables will make the 534 sound thick or lean, and it needs top-quality isolation and support.
- The reviewer recommends buying the 534 new as they haven't auditioned the original from the beginning of the century.
- The only major flaw is that it doesn't have 500 watts per channel, but a custom one can be ordered for a very high price.
Comparisons (according to reviewers)
- Vs E.A.R. 890: The 890 is more robust and powerful, but not more convincing if your speakers don't need the power.
- Vs Cary Audio Custom 300B: The 534 is vastly superior.
Takeaway: The E.A.R. 534 is a musically convincing and transparent amplifier that reveals nuances in music. It is easy to place, beautiful to look at, and can make vocals and piano sound exquisite.
Video review
Our take on the brand
Our Summary
Product Strengths
- Sixty-five watts per channel provide plenty of power to drive many speakers
- Different output tubes can be used, such as EL-34s, KT-88s, 6550s, and KT-120s, as long as they are biased
- A built-in, high-quality current metering system allows for instant selectable anode current for biasing, making it a tube roller's dream
- The headphone amplifier uses the power amp's output stage instead of op-amps, making it smooth, detailed, and exhilarating
- Sounds warm and a little tubey, providing a musical and satisfying experience
Product Considerations
- Has five inputs, all unbalanced RCAs, with no inboard phono and no internal DAC
- No XLR compatibility
Comparisons (according to reviewers)
- Allnic Audio T-2000 integrated amplifier had a quartet of KT-170s, and it was one of the reviewer's three favorite integrated amplifiers of all time
- The sound with the EL-34s was more linear but somehow less interesting—less three-dimensional—when compared to the KT-150s
Takeaway: The Lab12 Integre4 is a well-made integrated amplifier that delivers a warm, huge, and detailed sound, making listening sessions memorable. With enough power to drive most speakers, it's a great way to attain joy and happiness at the same level as more expensive gear.
Video review
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