Tag Archives: Solid-state power amplifiers

Goldmund Telos 300 power amplifier

Goldmund Telos 300 power amplifier

From the Goldmund press release: Goldmund has released its latest Stereo Power Amplifier, a new product that can trace its lineage all the way back to the classic and compact Mimesis 3 amp from 1985. The new model brings together all of Goldmund’s latest evolutionary advances to its proprietary Telos amplification technology in a compact and stylish package. Delivering 225 watts of Class AB power per channel, the stereo amplifier follows in the Goldmund tradition of delivering its output over an extremely high 3Mhz bandwidth, to ensure the audio signal exhibits no unnatural group delays and phase irregularities within the ...

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Orchard Audio Introduces Starkrimson Stereo Ultra

The following is a press release issued by Starkrimson.

June 15, 2021 | Succasunna, New Jersey –  Following the enormous success of the Starkrimson® Mono amplifier, Orchard Audio is introducing the Starkrimson Stereo Ultra amplifier, with the same proprietary dual-feedback modulator and next-generation gallium nitride (GaN) transistors. Unlike its predicesor the Ultra amplifier delivers up to 500WRMS (1000WPEAK) of power and 20A of current while maintaining extremely low noise and distortion.

This latest design, which has already been previewed, tested and highly praised by those who were able to have access to it, fully explores the benefits of the latest GaN transistors, providing less harshness, cleaner highs, and better overall transparency and detail with irrelevant noise levels. The pulse-width modulation is performed completely in the analog domain before being amplified by the GaN power stages. Starkrimson amplifiers use Leo Ayzenshtat’s proprietary DC-coupled, fully balanced dual feedback modulator, which allows the amplifier to be completely balanced from input to output, through the use of bridged GaN power stages.

This design provides the Starkrimson Stereo Ultra amplifiers with a huge reserve of power for extended transients, and the power expands linearly with the load – 125 watts into 16 ohms; 250 watts into 8 ohms; and 500 watts into 4 ohms – for powerful, unrestrained music. The amplifier is packaged in an aluminum and steel chassis with high-end gold-plated binding posts and connectors, with a front panel option of either matte black or brushed aluminum (silver).

Features:

  • Fully balanced from input to output (w/differential input)
  • Differential and single-ended audio inputs
  • Extremely low noise and distortion
  • 2-ohm capable
  • 20A of output current

 

Specifications:

  • Signal-to-Noise Ratio (SNR): 120dB (A-weighted, 22kHz BW)
  • Frequency response: DC – 80kHz+
  • Gain (balanced input): 19.05dB
  • Gain (single-ended input): 25.05dB
  • Power output into 16/8/4Ω: 125/250/500WRMS

 

Orchard Audio is still offering preorder prices ($1,999.95 USD) on its website until the end of June 2021. Starkrimson Stereo Ultra amplifiers will start shipping in August and are available with differential (XLR) and single-ended (RCA) inputs or both ($150 option). All DIY enthusiasts can also order the Starkrimson Ultra Mono Amp Module and kits separately, in order to build their own systems.

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First Watt F8 Stereo Power Amplifier

By my count the F8 represents the sixteenth First Watt power amp authored by the undeniably prolific Nelson Pass. Each unit has been a unique creation said to be “best” in some particular way, though they all happen to look similar because they use the same basic chassis and power transformer. The F8 represents a variation on the popular J2. Its origins go back to 2015, when Nelson had the notion to create a design similar to the J2, based on the SemiSouth Silicon-Carbide R100 power JFET, but using an alternative front-end gain stage. The prototype, says Nelson, was a clear improvement, but because of the J2’s popularity the decision was made to wait. After some additional work over the past six years, that alternative design was finally released as the F8. It is a stereo single-ended Class A amplifier with only two gain-stage devices per channel, a single Toshiba 2SJ74 JFET input, and the SiC R100 power JFET output. Both of these transistors are no longer in production, but available in limited quantities from the First Watt new-old-stock “vault.”      

Circuit-wise, the F8 is quite similar to the J2 amplifier with a virtually identical output stage. However, only one front-end transistor is used instead of six, and it is operated as a current-feedback amplifier as opposed to the J2’s voltage-feedback design. One consequence is reduced gain (only 15dB), but according to Nelson, a simpler front end is more consistent with the single-ended approach to amplifier design and pays off in a purer second-harmonic character, less distortion with lower negative feedback, greater bandwidth, and a higher damping factor. Specifically, comparing the published specs for the J2 and F8, it’s clear that the F8’s damping factor and high-frequency response are twice as good, and that its THD is 0.02% versus the J2’s 0.03%. Unlike the J2, the F8 does not have a balanced input. It also incorporates AC output-coupling in the form of two large electrolytics (10,000µF each) in parallel, bypassed by one polypropylene cap, to eliminate any DC at the output. The resultant bass roll-off frequency is 1Hz. 

Power output is similar, as well. Keep in mind that this is a low-power amplifier, 25Wpc into an 8-ohm load and half that into a 4-ohm load. As such it needs to be carefully matched with a compatible speaker. An 8-ohm speaker with a minimum sensitivity of 90dB would be ideal. The Fleetwood DeVille that I grew quite fond of this past year (and reviewed in Issue 309) was used for all the listening tests. It certainly meets the requirements and offers a sensitivity of 94dB, to boot. The F8’s power dissipation is 170 watts to produce an output of 25Wpc, which means quite a bit of waste heat. Be sure to allow plenty of ventilation around the chassis. Even so, it runs fairly hot to the touch after about an hour of being powered up.

first watt f8 rear

So what does it sound like? Well, it turned out to be the sonic equivalent of Reyka, an Icelandic vodka that has been said to taste dangerously close to fresh water. The F8 started off much like a tabula rasa, a clean slate, distinguished by the absence of inherent sonic colorations. It didn’t sound bright or warm, but consistently took on the flavor of whatever front end I threw at it. That’s not to say that it didn’t have its own sonic imprint. To my way of thinking, what it did right was a logical consequence of a confluence of three factors: simple single-ended circuit topology, wide bandwidth, and an excellent damping factor. 

The resultant airy treble, tonal purity, and superb transient speed were instantly endearing. So was its startling soundstage transparency. It shouldn’t come as a surprise when I tell you that my favorite matching preamp was of the vacuum-tube variety. The F8 allowed tube virtues such as a deep and layered soundstage to shine through, while maintaining an authoritative midbass. Tympani strikes were staggering; drum kits were persuasively resolved with satisfying kick-drum crunch; and brush work was delicate. It was like having your cake and eating it, too. The upper bass and lower midrange weren’t shabby, either. On my favorite performance of the Dvorˇák Cello Concerto in B Minor, with Jacqueline du Pré and the Chicago Symphony Orchestra conducted by Daniel Barenboim [EMI CDC-7476142], the loving collaboration of soloist and orchestra shone with emotional intensity and uncommon clarity. 

When it came to macrodynamics, 99% of the time I didn’t feel that I was missing anything. On a rare occasion, on highly dynamic material, there was a hint of compression. But most of the time the F8 didn’t sound at all like a low-power amp. It managed to project plenty of authority through the power range of the orchestra. Coupled with its robust boogie factor, it was able to extract the music’s dramatic content with total conviction.

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Parasound JC 1+ Monoblock Power Amplifier

In Oscar Wilde’s novel The Picture of Dorian Gray, the flibbertigibbet Lady Henry observes, “I like Wagner’s music better than anybody’s. It is so loud that one can talk the whole time without other people hearing what one says. That is a great advantage, don’t you think so, Mr. Gray?” Dorian doesn’t miss a beat. “I am afraid I don’t think so, Lady Henry,” he replies. “I never talk during music—at least, during good music. If one hears bad music, it is one’s duty to drown it in conversation.”

By this humorous standard, when listening to the new 450-watt Parasound JC 1+ monoblock amplifier, my guess is that you’re not liable to engage in much small talk because it makes most music sound so good. “JC” are the initials of legendary audio engineer John Curl, who has given his original JC 1 design a complete overhaul. [John Curl was inducted into The Absolute Sound’s High-End Audio Hall of Fame in 2018, Issue 289. —RH] As it happens, I used a pair of the original JC 1 Class AB monoblocks for several years to power Magnepan 1.6 loudspeakers, which prospered from the clean current that those amps provided. Any Magnepan lover knows that these big panels suck up watts like almost nothing else in the way of loudspeakers on the planet, but also that the sonic rewards can be great. In this case, they were.

Naturally, I was curious to hear what Parasound and Curl had accomplished after almost two decades. On paper, the revisions to the JC 1 appear to be extensive. It boasts a new power transformer with 20% higher capacity than its predecessor, as well as Nichicon power-supply filter capacitors that have been increased in capacity from 132,000uF to 198,000uF. Both measures typically translate into an increased stability that provides a wealth of sonic benefits, including better imaging and dynamics. The amplifier also employs Bybee Music Rails to help eliminate the input-stage noise that can have a deleterious effect on tonal purity. The amplifier has a two-position toggle switch that allows you to choose between 23dB or 29dB of gain, depending on the sensitivity of your loudspeaker. With the Wilson Audio WAMM Master Chronosonic loudspeaker, I relied upon the 29dB setting. The amp also sports two nifty pairs of CHK Infinium speaker terminals that grasp the loudspeaker cable lugs very firmly, indeed. As long as you insert the lugs straight up into the terminals, the CHKs are a breeze to use; deviate, however, by even a millimeter, and the lugs simply won’t glide in. At 83 pounds (the original was 63), these amps are no lightweights, but they’re not too difficult to maneuver into place by yourself.

As with most big powerhouse amps, it’s always tempting right away to declare, like the Thing in the Fantastic Four, “It’s clobberin’ time!” Whether running the Parasounds on the subwoofers or the front speakers of my system, I consistently found that they can, as you would expect, deliver quite a wallop. Initially, I ran the Parasounds on my subwoofers to break them in and to test their mettle on the deepest bass passages. Quite frankly, I was taken aback by what they brought to the table in the bass realm. They seemed not simply to plunge down more deeply into the nether regions, but also to more fully energize the notes themselves. This was apparent on both CDs and LPs. On a Decca pressing of the Solti recordings of the Wagner operas—recently bestowed upon me by Ali Saad, a classical aficionado and avid audiophile in Los Angeles—the forging of Siegfried’s sword came through with a remarkable clang, resounding to the back of the room. Jeepers, creepers! It was though the Parasounds were delivering the current into the loudspeaker unmediated by cables or anything else. I consistently found that the Parasounds not only increased the dynamics of my overall system, but also the perceived sense of hall space. It’s been said, time and again, that subwoofers play a pivotal role in defining the soundstage dimensions of a recording, but it’s always a pleasure to hear the phenomenon vividly demo’d, as it was with the JC 1+. 

As tempting as it might have been to retain the Parasounds on the subs, duty called. It was time for the Full Monty. I ventured to the recesses of my listening room, eyed the Parasounds for a moment, then hoisted them into the air, one at a time, mind you, to install them on my main loudspeakers. The results were quite revealing. 

The first thing I noticed was that same sense of enveloping space I’d heard with the subwoofers. On a BBC Music CD that I recently received, a whoosh of ambient hall and audience sound came through even before the music began, followed by Frederick Delius’ pleasant trifle “On Hearing the First Cuckoo in Spring,” a tone poem he composed in 1912. It features an onomatopoetic cuckoo call that is sounded first by the woodwinds, then the strings. With all that surplus power on hand—the first 25 watts in Class A—the Parasounds vividly conveyed the sweeping and shimmering sound of the orchestra, turning it into an engrossing experience. In part, the Parasounds possess such an enveloping character because of their ability to plumb the depths with satisfying richness and grip. 

To give their ability to stand up to a real high-powered orchestral performance a go, I played an old EMI, Herbert von Karajan conducting the Berlin Philharmonic on Sibelius’ tone poem Finlandia. This one has it all—melodrama, pathos, and grandeur. Right from the outset, the Parasounds delivered the staccato trumpet fanfare with precision and alacrity. No less impressive were the timpani whacks, which were never drowned out by the orchestra, but clearly audible in all their majestic force. There was none of the smearing or congealing or discombobulation of the various sections of the orchestra that you might expect with a lesser amplifier, without the power to keep everything from spiraling out of control. On the contrary, the JC 1+ kept the proceedings firmly in hand right up through the very grand finale, as the orchestra crescendos triumphantly while the tympani delivers a sustained roll—a kind of emphatic period to the overture. Once again, the clear delineation of the tympani even as the orchestra was playing full bore was most impressive.

Another blockbuster was a CD on the Sony label called Oriental Trumpet Concertos that features the Hungarian trumpeter Gabor Boldoczki playing Alexander Arutiunian’s Trumpet Concerto in A-flat major. The Parasounds effectively captured the velvety sound emanating from the bore of Boldoczki’s trumpet, as well as the more nasal quality when he deployed a straight mute for the wonderfully plangent and meditative middle movement. On the cadenza that wraps up matters with a triumphant finish, the trumpet almost sounds as forceful as a machine-gun, as Boldoczki double-tongues the sixteenth notes. The transient dynamism of the amps was consistently apparent on trumpet recordings—it was as though the music were snapping to attention, like a soldier crisply saluting a flag.

As noted, the spaciousness and power of the sound has a lot to do with the bass control of these amplifiers. On a very fine recording by Stephen Hough of the final piano pieces of Brahms [Hyperion], the rumbling of the piano in the subterranean regions was quite palpable. On both the Fantasias and Intermezzos, both the delicacy and lingering quality of Hough’s touch were discernible as his left hand traveled down the keyboard. I’ve rarely heard such fidelity and accuracy in the bass as I did with the Parasounds. The PS Audio M1200, an amplifier based around a tubed input and switching output stage, may have gone even deeper, but I don’t think it boasted the same grip, or, to put it another way, the same variety of timbres. 

I heard something similar in terms of bass fidelity on an oldie but goodie, the Concord label album called “Don’t Forget the Blues,” which sounded unforgettable. On the song “Rocks In My Bed,” Ray Brown’s bass was tautly defined, moaning and groaning as he accompanied the superb trombonist Al Grey, a master of the wah-wah mute, if there ever was one. If the sound of Brown’s bass line were a rubber band and any tauter, it would have snapped in two. 

How did the Parasounds perform on more delicate fare? You’ll get few quibbles from me, friends. There were moments when I was simply startled by the finesse that they offered. On Louis Bellson’s album Thunderbird, for example, I was smitten by the rendition of the Neal Hefti standard “Softly With Feeling.” The Parasounds were able to provide the hushed backing of the winds with total control, endowing the song with a sense of realism that it would otherwise have lacked. This was one of those times when this LP on the Impulse! label really sounded opened up rather than claustrophobic. I mean talk about pristine. Suffice it to say, that the Parasounds conveyed, or appeared to convey, just about every last little nuance the cartridge excavated from the black grooves.

But even on the delicate passages, the sound was never wispy. Take the magnificent album Festival of Trumpets [Nonesuch]. It was mastered in 1974 by Bob Ludwig and features the New York Trumpet Ensemble, directed by Gerard Schwarz. I was riveted, among other things, by a lovely Sonatina by the baroque composer Johann Christoph Pezel, who himself  played trumpet and violin. The gossamer-like trumpet playing of Schwarz and Louis Ranger sounded very enticing, but it was the accompaniment of the bassoon and harpsichord that really caught my ear. It’s easy for them to get lost in the mix. But here it was easy to hear the pleasingly sonorous sound of the bassoon as it puffed along, as well as the soft and deliberate plucks of the harpsichord. If I had to pick a nit, it would be in the treble. It’s not that the sound ever became hard or dirty—the Parasound always has a rich, warm, inviting sound on top—rather, the amp could sometimes be less slightly transparent and pellucid on top than some of its far-pricier brethren.

The JC 1+ shows just how far amplifiers have come in the past several decades. Always a stalwart, it has been vastly improved in its latest incarnation. Both consummately reliable and stellar in performance in my listening room, it offers a beautifully refined, flowing, and organic presentation of music. It is clearly voiced on the sumptuous and warm side, which is to say it has the breath of musical life. I could listen to it for hours and hours, and did. 

No doubt you can spend a lot more money on amplifiers ranging from $50,000 and up, and I’d be the last to dissuade anyone from chasing audio rainbows as vigorously as they please. The gains will be there in tonality, dynamics, and filigree of detail, particularly in the treble. But the JC 1+ monoblocks come so darned close to the best, in so many categories, that for more than a few listeners it may seem an otiose pursuit to look elsewhere. Parasound and John Curl deserve a rousing round of applause for producing a real-world-priced amplifier that delivers otherworldly sound.

Specs & Pricing

Type: Monoblock solid-state power amplifier
Power output: 450 watts @ 8 ohms; 850 watts @ 4 ohms; 1300 watts @ 2 ohms
Class A power output: 25W, bias switch set to high; 10W, bias switch set to low
Frequency response: 2Hz–120kHz, +0/-2dB; 20Hz–20kHz, +0/-0.25dB
Total harmonic distortion (THD): <0.15 % at full power; <0.02 % at typical listening levels
IM distortion: <0.03 %
Damping factor: >1200 at 20Hz
Input impedance: Unbalanced, 50k ohm; balanced, 100k ohm (50k ohm per leg)
S/N ratio, inputs shorted: >122dB, IHF A-weighted, bias set to Low; >120dB, IHF A-weighted, bias set to High; >113dB, unweighted, bias set to Low; >111dB, unweighted, bias set to High
Dimensions: 17½” x 7¾” x 20″
Net weight: 83 lbs.
Price: $8495 each

PARASOUND PRODUCTS, INC.
2250 McKinnon Avenue
San Francisco, CA 94124
parasound.com

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Chord Electronics ULTIMA 5 stereo power amplifier

Chord Electronics ULTIMA 5 stereo power amplifier

At the risk of stating the obvious, these are turbulent times. Little in life can be confidently relied upon. So, it is, perhaps, more gratifying than it really should be, to find the unflappable Chord Electronics forging serenely ahead on a path unsullied by U-turns, flip-flops or ‘alternative facts’. Lately, of course, Chord Electronics has been making all sorts of disruptive waves with its digital products. Combining giddily high standards of performance with reliably ‘interesting’ product names, Chord Electronics’ range of DACs, streamers and upscalers has given the company plenty of exposure in the audio mainstream. But all this (very ...

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Simaudio MOON 860A v2 Power Amplifier

Simaudio MOON 860A v2 Power Amplifier

Some products and some companies are just noisy – literally, metaphorically or euphemistically. Others are calmer, quieter and altogether more understated. For the last couple of decades, Simaudio has been consistently responsible for some of the best value, best performing and most reliable (semi-)affordable amplification on the market. From super-musical integrateds to the pocket-battleship 400M mono-blocs, these have been go-to products for review and recommendation, demonstration and daily deployment. Nor is the company any stranger to technological innovation or innovative concepts; the excellent MiND network replay solution continues to win. MOON has been evolving and improving its products, working its ...

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Gryphon Audio Designs Essence preamp and power amplifier

Gryphon Audio Designs Essence preamp and power amplifier

By most normal standards, the Essence pre/power amplifier combination would represent the uppermost tier of product performance, size, weight and price. In Gryphon Audio Design’s world, Essence is the starting place in its pre/power line. There is a long way to the top of the Gryphon tree. Essence is the new preamplifier and power amplifier line from the Danish brand. It joins the Scorpio S CD player, the Diablo 120 and 300 integrated amplifiers and possibly Mojo S loudspeaker at the start of the line. Although no-one’s going to call a preamp costing £20,299 in its full configuration and £17,800 ...

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PS Audio Stellar M1200 Amplifier

Mention the words “switching” and “amplifier” in tandem and not a few audiophiles are apt to get a queasy look. The knock on Class D amplification is that it tends to sound cold, sterile, amusical. For the most part, there has been something to the opprobrium that has attached to switching amplifiers. So when I saw that PS Audio’s inventive engineer Darren Myers had come up with a switching amplifier called Stellar M1200, I was most curious to hear it. 

The design of the monoblock M1200, which is priced at $5998 per pair, seems calculated to try to overcome the traditional objections to Class D amplifiers. The input section features a venerable 12AU7 tube coupled to a high-current ICE Edge output section. The idea, as near as I can tell, is to try and mate beauty and the beast. And why not? The advantage of Class D amplifiers is that they don’t really produce any significant heat, weigh very little, consume minimal electricity, and deliver a whopping amount of power—in the case of the M1200 no less than 1200 watts into a 4-ohm load, enough to drive just about any extant loudspeaker with ample headroom to hit sonic peaks loud enough to satisfy the most demanding listener.

When I first spotted the M1200, I reckoned that it would be able to drive my Wilson WAMM Master Chronosonic subwoofers easily. I couldn’t help wondering what all that power would be like on the bottom section of my loudspeaker setup. As it happened, however, my system was in flux, with gear whizzing in and out the door; so, I put the M1200s first on the WAMM main loudspeakers without harboring too great expectations. Boy, was I in for a surprise! The M1200 is not a good amplifier; it is a superb one.

There were several enticing attributes of the M1200 that caught my ear, so to speak, from the get-go. The first one was the capacious soundstage that the M1200 produces. It’s always been my experience that the more powerful the amplifier, the larger and deeper the soundstage created by the loudspeaker. Joined to this is a sense of hall ambience, which is very important for a classical buff like me. The M1200 produced all of these in spades. 

On a fine Delos CD of the Brazilian Guitar Quartet playing transcriptions of Bach’s four suites for orchestra, the plusses of the M1200 were easy to detect. For one thing, there was a whoosh of air the instant the quartet began playing the second suite, each guitar firmly and forcefully planted in its own space. One of the attributes of the power that the M1200 offers is a sense of power and drive, not just of the overall performance but of a feeling of dynamic jump for each instrument. To a greater degree than I have heard with most amplifiers, the M1200 truly amplifies the smallest details—the hand of a guitarist inadvertently brushing the strings, a performer sucking his breath in, and so on. The accumulation of these small, almost microscopic, details add up to a more realistic overall sonic landscape. Instruments, whether trumpet, guitar, or violin, emerge as formidable in size and scale.

At the same time, the M1200 is something of a jackrabbit. The amazing damping factor of the amplifier means that it often seems to start and stop a hair faster than many other of its brethren. No matter the musical genre, the feeling of a sense of propulsion is inescapable. In many ways, the music seems to be happening in real time as opposed to that subliminal sense of a split-second time lag. On a Philips LP of Schubert’s sonatas for violin and piano that’s beautifully played by Arthur Grumiaux and Paul Crossley, this alacrity endows the music with a sense of drama. Grumiaux’s bowing has more bite and fervor than most systems would render, as do Crossley’s fortissimos. In my experience, it’s pretty difficult to reproduce a violin’s overtones—the guts of the sound—with any real degree of verisimilitude. The M1200 excels at it. The hall ambience it coaxes into your listening room also means that the lower regions of the piano resound with great fidelity. The piano chords have a 3-D dimensionality to them that is quite winning, particularly in the bass region. Ah, the bass region. I’ll admit it. I’m something of a bass fanatic, and not just because my system is located in the basement. Nor is it that I’m intent on pounding out the low bass on rock recordings, though I’ll confess that I enjoy it upon occasion. No, what I really find illuminating is the degree to which improvements in the bass further the illusion of the real thing throughout the frequency spectrum. In controlling the bass quite authoritatively, the M1200 is able to reproduce effectively the timbral richness of a grand piano, tuba, or guitar. It goes deeper than many competing amplifiers, something that came through vividly on a Pentatone SACD of Bram Beekman playing Bach’s Organ Concerto in D minor. The sustained low organ notes are held with a tautness, even as the melody plays above, that makes for a rewarding listening experience. Ditto for a praeludium by Johann Christoph Kellner; I’ve never heard it better. The linearity of the amplifier means that every note, from bass to treble, exploded out of the loudspeaker with equal force on massive organ block chords. The sound was rich and overwhelming. The depth of hall space was cavernous, as though you were in the cathedral itself feeling the sonic waves emanating from the organ. Forget about the fumbling around that you sometimes hear with other amplifiers that are trying to grasp the very lowest reaches of the organ. The M1200 handles them with aplomb. You’ll hear every note, loud and clear. 

What about the treble region? Here, as you might expect, there are some plusses and minuses. The excellent transparency and power of the M1200 allow it to soar wide open in this fussy sonic region. The grip and control on violin and piano or vocals is most impressive. Take the German counter-tenor Andreas Scholl. On a Harmonia Mundi recording of Bach cantatas, it is impossible to detect a hint of compression with the M1200 when Scholl cuts loose. You can also practically hear the air whooshing through the organ pipes on contemplative treble passages. The automotive equivalent would be flooring it on the Autobahn with no sense of hesitation. The power with the M1200, in other words, is always there, always on tap, always ready to deliver. 

But—you knew there was a “but” coming—the M1200 is simply not on the level of costlier amplifiers in offering an unimpeachable treble region when it comes to tonality. In my view, the M1200 closes the gap between switching and Class A/B amplifiers to a remarkable degree—but not all the way. It has great clarity, but simply remains a little tonally thinner on top than other top-flight amplifiers.

The M1200 poses a real challenge for much of the audio industry. It offers a colossal sound and excellent refinement at what has to be considered a budget price for the high end. PS Audio, which has specialized in power regeneration for many years, is really expanding its ambit. For anyone who has a loudspeaker that is difficult to drive the M1200 is a must-audition. It does so many things so well that it is consistently a joy to listen to in my system. 

Of the amplifiers that I’ve auditioned in this price range, the Stellar M1200 is by far the best, a gangbuster piece of gear that upends many old verities about switching amplification. I could live with it for a very long time. Stellar, indeed.

Specs & Pricing

Frequency response:10Hz–20kHz ±0.5dB, 10Hz–45kHz +0.1dB, -3.0dB
Output power: 600W into 8 ohms, 1200W into 4 ohms.
Signal to noise: > 112dB, [email protected] watts
Gain: 30.5dB
Output impedance: <0.007 ohms, 50Hz, 2.8Vrms
Damping factor: >550 at 50Hz, 2.8Vrms, 4 ohms; >1100, 8 ohms
Inputs: RCA (unbalanced), XLR (balanced)
Outputs: Copper-base nickel-plated binding posts (two pair)
Dimensions: 17″ x 3.75″ x 12″
Weight: 27 lbs. (each)
Price: $5998/pr.

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CH Precision L10 line-stage preamplifier and M10 twin-chassis power amplifier

CH Precision L10 line-stage preamplifier and M10 twin-chassis power amplifier

You might well think we’re getting pretty good at this hi-fi thing. After all, we’ve been at it a while and, reading the press, you could easily conclude that, as the parade of ‘latest, greatest’ products continues to pass, we must be on an inexorable upward trajectory. Surely perfection awaits – just beyond the next rise. Yet perfection – just like tomorrow – seems to be always a day away. With pages to fill and audible differences to report, the distinction between different and better all too often gets blurred. But occasionally – just occasionally – a product arrives that ...

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NAD C658 Streaming DAC and C298 Power Amplifier

NAD’s new C658 streaming DAC packs a huge number of advanced technologies and capabilities into an affordable package. The C658 is a BluOs-enabled streamer that incorporates a DAC with MQA decoding, support for about a dozen music-streaming services, network connectivity, a full suite of preamplifier functions, a moving-magnet phonostage, two subwoofer outputs with configurable crossover, and Dirac Live DSP room correction. You can add inputs now and in the future, thanks to NAD’s Modular Design Construction architecture. The C658 even has a Bluetooth aptX HD receiver/transmitter so that you can listen to music through your wireless headphones. The price? $1649. 

A logical partner for the C658 is NAD’s brand-new, $1999 C298 stereo power amplifier. It, too, is packed with features, including balanced and single-ended inputs, variable gain, line outputs for daisy-chaining multiple amplifiers, a bridging function for monaural operation, an auto-on feature when signal is detected, and remote control. The C298 is one of the first amplifiers to feature a new circuit, called Eigentakt, that is a significant advance in Class D amplification. The Eigentakt output-stage module, created by a new Danish company called Purifi, has extraordinary specifications, including vanishingly low distortion or noise. The design effort was led by Bruno Putzeys, one of the brightest thinkers in switching-amplifier design (Putzeys created the Hypex Ncore Class D module that is the basis for dozens of high-end amplifiers. I describe this new switching-amplifier module, which you are likely to see in many upcoming high-end products, in a sidebar.) 

The C298 is the third NAD amplifier based on the Eigentakt module. The previous iterations are the Masters M33 and M28, each priced at $4999. The C298 is the company’s first attempt to bring the technology to a much lower price point, largely by eschewing the fancy casework of the Masters Series. The C298 is rated at 185Wpc into 8 ohms and 340Wpc into 4 ohms, with a dynamic power rating of 260W into 8 ohms, 490W into 4 ohms, and 570W into 2 ohms. When bridged to operate as a monoblock, the C298 can output a staggering 1000W into 8 ohms.

The C658 network streaming DAC can accept a wide range of inputs (see Specs & Pricing), but will probably be used primarily via its integral support for music-streaming services, and be controlled through the BluOS app. (A full-function remote control is also included with the C658.) BluOS is a wireless digital ecosystem for connecting and controlling a variety of products, including whole-house wireless-audio distribution.        BluOS is a multi-room wireless platform developed by Lenbrook International, and is a sister brand to NAD. BluOS offers a full suite of compatible products for any application. After downloading the app (iOS or Android), you select the BluOS device to stream to, choose music from a streaming service, and enjoy. I logged in to my Tidal and Qobuz accounts, which gave me access to all the music I wanted. You can also connect to any network-attached drives and play music stored on them. Music management is handled through the BluOS app. The C658 shows up as a Roon endpoint (the  C658 was recently Roon certified). BluOS recently made a deal with the Neil Young Archives to provide BluOS users full and free access to the iconic musician’s catalog, all in high resolution. BluOS is compatible with PCM up to 192kHz/24-bit, but lacks DSD support. The optional USB input module will accept DSD up to DSD512, but converts it to PCM at 192/24. The module also accepts USB 2 audio from a computer. Finally, the BluOS app offers a range of free Internet radio services in addition to the paid streaming platforms.

The C658 also allows you to name inputs, set auto-standby time, disable inputs, select between fixed and variable output levels (fixed is the “theater-bypass” mode), trim the gain on each input, engage or bypass the tone (bass and treble) controls, and adjust the display brightness. On the technology side, it’s built around the ESS Sabre 32-bit DAC. The volume control operates in the digital domain, except when the C658 is in the analog-bypass mode.

The C658 is the first NAD Classic Series two-channel product to incorporate Dirac Live. Dirac Live is a DSP room- and speaker-correction system that measures the frequency response and time signature of the sound at the listening position. From this measurement data, Dirac calculates a series of filters that flatten the frequency response and assure correct phase response at the listening seat. Those filters are then downloaded into the C658, which processes the audio signal before the C658’s digital-to-analog conversion stage. In essence, the system “pre-distorts” the audio signal in a way that is the inverse of the distortion created by your speakers and room. That is, Dirac Live modifies the signal driving your loudspeakers so that the final result at your ears is flat in frequency, with most of the sound energy in the room arriving at your ears in phase. Dirac Live doesn’t just look at amplitude information, but also at the room’s time signature. It distinguishes between deleterious reflections, such as floor and ceiling bounce, and later-occurring and lower-amplitude reflections that sound like natural reverberation. 

The version of Dirac Live included with the C658 corrects frequencies up to 500Hz. For the full-frequency-range version, you must pay $99 for the software upgrade. A future software upgrade will provide extensive control over the C658’s subwoofer-output signals. Specifically, it will include a bass-management function as well as clever tricks, such as causing one subwoofer’s output to cancel a standing wave created by the other subwoofer. That feature is like having an active room-resonance-cancelling device built right into the C658 (provided that you have two subs). The C658 hardware, including the two subwoofer outputs, can accommodate this new feature when it becomes available.

Because Dirac Live operates in the digital domain, analog signals at the C658’s input are digitized, processed, and converted back to analog at 192kHz/24-bit. Fortunately, you can bypass the digital conversion on specified analog inputs so that the C658 operates as a pure analog preamplifier. Those bypassed inputs, however, cannot be processed with Dirac Live, and the DSP subwoofer crossover won’t be accessible. (See the sidebar for more about setting up and running Dirac Live.)

Overall, the C658 was fairly easy to operate considering its extensive features and capabilities. I quickly became accustomed to the BluOS app. In typical NAD tradition, the two products’ casework is utilitarian rather than lavish; NAD spends the parts-budget on those components that affect the sound quality. If you prefer a more upscale chassis, NAD offers the Master Series of components.

Listening

I auditioned the C658 and C298 separately in my reference system before using them as a pair. This put each product under the microscope of reference-quality sources, electronics, cables, and the Wilson Chronosonic XVX loudspeakers. For a more real-world situation, I paired the two NAD components with a speaker of commensurate price, the Focal Chora 826, a floorstanding three-way that sells for $2200-per-pair (review upcoming in the April issue). The complete system, without cables, was $5848. I ran balanced interconnects between the two NAD components.

I connected the C658 to my network via an Ethernet cable. NAD also sent to me the Bluesound Pulse 2i, an all-in-one tabletop system ($699) that connects to the BluOS network wirelessly (as I used it) or via an Ethernet port. NAD wanted me to experience how products like the Pulse 2i allow BluOS to function as a whole-house wireless audio system. I wasn’t expecting to receive the Pulse 2i, but discovered that it was a great way to have music outside the listening room. There’s the joke that the audiophile’s way of realizing whole-house audio is to open the listening room door and turn up the volume. I must confess to taking that approach myself. But the ability to place the Pulse 2i in the kitchen, for example, and have full wireless access to high-resolution streaming music controlled by my iPad was compelling.

Starting with the C298, the amplifier had more than enough power to drive the Wilson Chronosonic XVX to any listening level without strain. Even on music with very wide dynamic range (John Williams at the Movies on Reference Recordings) the C298 had plenty of pluck. Peaks were reproduced effortlessly; the bottom end stayed tight and defined at high playback levels; and the soundstage didn’t collapse during the loudest and most complex passages. NAD has long been a proponent of amplification with lots of dynamic headroom, which could be defined as the difference between the amplifier’s continuous power rating on the spec sheet and the clipping point on musical peaks. This approach makes sense; music is dynamic and much of its expressiveness is contained within those dynamic contrasts, and not on steady-state tones. It’s worth noting that the Eigentakt Class D output module is rated at 400W, but NAD specifies the C298’s output power at 185Wpc into 8 ohms. Clearly, there’s a generous amount of headroom.

As with other Class D amplifiers I’ve auditioned, the C298’s bass reproduction was outstanding. This amplifier goes deep, has a nice sense of heft and weight through the midbass, and has terrific dynamic punch on instruments such as kickdrum. An acid-test of bottom-end impact is the track “Octopia” from drummer Simon Philips’ album Protocol II (Qobuz 96/24). In addition to first-rate performances by the entire band (including great guitar work by Andy Timmons), this album showcases Philips’ phenomenal talent, recorded with spectacular drum sound. His huge kit includes many low-tuned toms that put the C298 to the test. The C298 did justice to this album, sounding like an unflappable powerhouse and reproducing the kit with effortless dynamics and impact. 

But it wasn’t just all sledgehammer impact; the C298 also revealed dynamic subtleties and nuance. Throughout the listening, I noticed that the C298 had an unusually satisfying ability to convey music’s rhythmic flow and forward propulsion, from the funky grooves on bassist Brian Bromberg’s Thicker than Water (Tidal MQA) to Ray Brown’s hard-swinging acoustic bass on Soular Energy. This could be the result of the C298’s extremely low output-impedance, which translates to the amplifier having an iron-fisted grip over the loudspeakers’ woofers—either the Wilson’s 12.5″ and 10.5″ drivers or the pair of 6.5″ woofers in the Focal speakers.

The midrange had a nice presence on Norah Jones’ voice on her album Day Breaks (Tidal MQA). Her vocal had good tonality, too, with just a touch of added sibilance. The upper-midrange to lower-treble was a bit forward in perspective, but only a bit. This character brought cymbals and the upper harmonics of instruments to the fore, imparting a lively quality to the sound. Significantly, the C298 lacked the “chalky” haze over the mids and treble that I’ve heard from other switching amplifiers. Instrumental timbre was fairly natural, with excellent resolution of inner textural detail. The C298 was also remarkably adept at revealing subtle instrumental lines. It was easy to hear low-level instruments in the mix or at the back of the hall. The C298’s soundstaging was outstanding—big, open, spacious, and detailed, with precise image placement. If you think of amplifiers in this price as sounding flat, congealed, and a little grainy (compared to reference amplifiers), you’ll be in for a pleasant surprise with the C298.

Dropping the C298 into the middle of a system with $800k worth of source components, electronics, cables, and loudspeakers revealed just what a spectacular bargain this amplifier is. Although not the last word in timbral liquidity, the C298 does just about everything else at a level far above what its price would suggest. It was supremely musical and engaging, particularly the wonderful sense of rhythmic drive and ability to convey dynamic shadings and expression. I have not auditioned many Class D amplifiers, but can confidently say that the C298 is the best switching amplifier I’ve heard.

The C658, in this same system but feeding my reference amplifiers, revealed a good-sounding DAC at this price level. The overall tonal balance was neutral, but with a slight treble emphasis, heard as a bit of additional sibilance on voices. The top end also had a touch of sheen overlying instrumental timbre, and a slight layer of grain. This tended to affect recordings that are inherently bright, rather than blanketing all music. It’s by no means a deal-breaker, but I’ve heard smoother-sounding DACs. 

I was particularly impressed by the C658’s resolution through the midrange; the NAD revealed subtleties of texture and dynamics that are commendable for its price. The bottom end was well defined, and favored articulation over weight, making it easy to follow bass lines. Importantly, the C658 didn’t compress images in the soundstage into two-dimensional representations; rather, image outlines had some tangible space and air around them. The C658 had a good ability to present instruments and voices within a soundstage that was wide and well defined. Dynamics were similarly impressive, with the C658 having the ability to convey subtle nuances of dynamic expression such as gently struck cymbals. 

To get a better feel for the C658’s DAC section performance, I compared it to the AudioQuest DragonFly Red, a $199 overachiever. Although the two products couldn’t be more different in function and capabilities (the DragonFly is a USB stick with no features other than MQA decoding), the AudioQuest, nonetheless, provides a benchmark for what is possible at an entry-level price. The NAD’s bass was a little lighter in weight but more detailed than that of the DragonFly, which was a bit loose and billowy. With the NAD it was easier to follow bass lines, and the overall tonal balance sounded more natural, with the bass better integrated into the rest of the music. The C658 had a much wider and deeper soundstage, with greater spread and separation of instruments in the hall or in the multichannel mix. I also heard greater midrange resolution from the NAD, which better revealed subtle details about how instruments make sounds. The acoustic guitar accompaniment on Norah Jones’ “Come Away With Me” sounded more natural and realistic through the NAD. Overall, the C658 was significantly better sounding than the DragonFly Red. It may not seem fair to compare a $199 USB stick to a $1649 full-featured product; nevertheless, the comparison puts the C658’s DAC performance into perspective. Although you can find better-sounding DACs at the C658’s price, they won’t have the NAD’s extensive capabilities—full preamplifier functions, phonostage, subwoofer outputs with configurable crossover, streaming under BluOS control, and, most significantly, Dirac Live DSP room correction. 

Next, I moved on from the Wilson Chronosonics and listened to the C658 and C298 driving the Focal Chora 826 for some time before engaging Dirac Live room correction. (See the sidebar on setting up and running Dirac Live.) Starting with the stock version that corrects up to 500Hz, I could see in the measured response two peaks of excessive energy in the range from about 80Hz to 180Hz, with two dips below 80Hz. The target curve showed a smoother response after correction, with the gently rising bass of the NAD target curve. In the listening seat, engaging Dirac resulted in more low bass and less midbass bloat. The Focal Chora 826 almost sounded almost like a different speaker in the low end, with greater depth and extension. Kickdrum had more impact, with seemingly much steeper and faster transient attack, coupled with quicker decay. The musical effect was greater punctuation of the rhythm. With the midbass bloat removed, it was much easier to hear nuances in bass playing; pitches were more clearly articulated; and, most significantly, I could more easily hear the starts and stops of each note. With Dirac, individual notes were more distinct in pitch and dynamics. This was true across a wide range of music, from Ray Brown’s acoustic bass on the previously mentioned Soular Energy to Brian Bromberg on Thicker than Water. The overall tonal balance was somewhat lighter and leaner, but this leaning out of the midbass was entirely salubrious; the sound still had plenty of weight and authority, but was cleaner, tighter, and more intelligible.

That impression was with the Dirac version that comes free with the C658, which corrects up to 500Hz. Below this frequency is where room modes are most problematic, and this version of Dirac results in a remarkable transformation of the bass and low bass.

I then switched to the full-frequency-range version, a $99 upgrade, and again measured the system and loaded the new filters from my PC into the C658. I’ve generally believed that it’s best not to try to correct higher frequencies with DSP, for several reasons. First, it’s easy to dramatically change the sound of your speakers (which you presumably like) and get “lost in the woods” trying to find the right tonal balance. It’s easier to do more harm than good. Second, correcting higher frequencies is much more technically challenging that correcting lower frequencies. In my previous experience, it’s best to use DSP to fix the bass and leave the rest of the spectrum alone. 

But that wasn’t the case with Dirac Live. The bass improvements just described were all there, but the effect on the midrange and treble was equally remarkable. Using the NAD target curve (the frequency response the correction system aims for), Dirac didn’t fundamentally change the Focal Chora 826’s smooth and flat tonal balance. Instead, engaging full-range Dirac produced a startling improvements in image specificity, in clarity, in the ability to hear individual instruments through the mix, and in transient response. Sounds started and stopped faster, with less overhang. I also heard a smoother upper-midrange and treble, with less hash. The sound was overall more refined. The impression of individual instruments within a soundstage was heightened.

The full-frequency version of Dirac Live is the most impressive DSP correction system I’ve heard. It is well worth the $99 upgrade. In fact, it made the $2200-per-pair Focal speakers sound like more expensive models.

I next tried Dirac Live with the Wilson Chronosonic XVX, a speaker with much greater bass extension than the Focal. The Wilsons are perfectly positioned in my built-from-scratch listening room, which has good dimensional ratios for evenly distributing room modes. Even with these advantages, rooms will still create peaks and dips in frequency response, caused by the interaction of direct and reflected waves, and between different reflected waves. Two waves combine constructively to produce a peak of energy at certain frequencies, or destructively to create a dip at certain frequencies. Those frequencies are determined by the room’s dimensions. After measuring the system and loading the correction filters for the Wilsons into the C658, I compared with no correction. I did hear an improvement in the bass, but it was an order of magnitude less than with the Focals. The bottom end was a bit more muscular and defined, with slightly better transient performance. 

After lots of swapping individual components in and out of the reference system, and experimenting with Dirac, I finally settled in for some music listening to the system as it was intended; the NAD pair driving the Focal Chora 826 with Dirac properly calibrated. I have to say that the performance of this $5848 system was outstanding, particularly in the bass. The bottom end was quick, articulate, punchy, and had outstanding resolution of pitch and dynamic shading. It was truly a full-range system with a terrific bottom end, a quality that’s very difficult to achieve without spending a lot more money. 

Conclusion

The C658 and C298 can serve as the heart of a capable and powerful music system. The C658 streaming DAC is loaded with all the features needed in today’s digital streaming world, has expandable inputs to accommodate future interfaces, and the BluOS app provides easy and intuitive control over a music library. The C658 can also serve as the heart of a whole-house wireless system. The C298 amplifier is a powerhouse that will drive virtually any loudspeaker. It also has qualities that are consistent with much more expensive amplifiers, including superb soundstaging, clarity of instrumental line, and good resolution of timbre. Bass and dynamics are spectacular, with excellent rendering of pitch and clarity of bass lines. The overall sound is slightly forward in perspective through the midrange and treble, a character that suggests attention to system matching. I can see the C298 delivering terrific performance when paired with much more expensive components. It’s that good.

I would have recommended this pair without Dirac Live, but this DSP speaker- and room-correction system vaults the performance to a new level, without the sonic compromises I’ve heard from some other DSP systems. The improvement in bass extension, clarity, and dynamics is astounding. The full-frequency version of Dirac brings newfound image specificity along with far more lifelike reproduction of transients.

Considered alone or as a duo, the C658 and C298 deliver exceptional performance and value.

Specs & Pricing

C658
Digital inputs: USB, 2x coaxial, 2x TosLink, Gigabit Ethernet RJ45, Wi-Fi 5 (802.11 ac/n), Bluetooth aptX HD (two-way); Apple AirPlay2, HDMI on optional MDC board
Analog inputs: Line in x2 (unbalanced), phono (mm, >80mV overload margin)
Analog outputs: Balanced on XLR jacks, single-ended on RCA jacks, subwoofer output x2
Other input/outputs: IR in/out, 12V trigger in/out, service USB
Formats supported: MP3, AAC, WMA, OGG, WMA-L, ALAC, OPUS, MQA, FLAC, WAV, AIFF; converted DSD supported only via BluOS desktop app
Dimensions: 17 1/8″ x 3 15/16″ x 16″
Weight: 22.3 lbs.
Price: $1649

C298
Output power: 185Wpc into 8 ohms, 340Wpc into 4 ohms
IHF dynamic output power: 260Wpc into 8 ohms, 490Wpc into 4 ohms, 570Wpc into 2 ohms
Mono IHF dynamic power: 1000W into 8 ohms, 1100W into 4 ohms
Inputs: Balanced on XLR jacks, single-ended on RCA jacks
THD: 0.005% at 1W-185W
SN ratio: >98dB (A-weighed, 1W output into 8 ohms)
Input impedance: 56k ohms single-ended or balanced
Dimensions: 17 1/8″ x 4¾” x 15 3/8″
Weight: 24.7 lbs.
Price: $1999

NAD ELECTRONICS
633 Granite Court
Pickering Ontario
L1W 3K1 Canada
nadelectronics.com

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