GamuT Di150 LE integrated amplifier

As Stereophile's true cub reporter—sorry, Herb Reichert, you're senior staff!—I work in the domestic fields of the high-end audio landscape. Meanwhile, my fellow Stereophile correspondents trot the globe, attending international audio shows, experiencing all the sweet spots offered by such far-flung locales as Munich, Montreal, and Northamptonshire, UK. Am I complaining? Not! But when an audio show of merit invades New York City, still the capital of the civilized world, you can believe I'm there on opening day, pen and pad in hand. The first rooms on my must-visit list usually include Audio Note UK, DeVore Fidelity, MBL—and, when the gear is warm and the good vibes flowing, as they usually are, Wes Bender Studio NYC.

Consider the typical high-end presentation at an audio show: machines clad in cool-to-the-touch brushed aluminum and other scientifically validated materials, voluptuous women beckoning you into suites hosted by men in suits, and sound and music that may be good, bad, or indifferent.

Wes Bender Studio NYC? Totally different experience. At the 2016 New York Audio Show, Bender provided booze, fun, and high-octane sounds. When I walked into Suite 814 of the Park Lane Hotel, Bender and GamuT's US distributor, Michael Vamos, were partying with the Rolling Stones, Santana's Abraxas (on Mobile Fidelity 45rpm LPs), Blood, Sweat & Tears, and singer Vanessa Fernandez's album of Led Zeppelin covers, When the Levee Breaks. A washtub overflowed with iced Hacker-Pschorr Weisse NaturtrÅb (a naturally cloudy hefeweizen, or yeasted wheat beer). I couldn't hear everything Bender was saying, but clearly audible were "crazy," "damned shame," and "buy the ticket, man!" Vamos, who resembles the 1970s actor Jan-Michael Vincent, pointed at the tub o' beer. In one corner of the suite, AudioStream.com's Michael Lavorgna, the ever-sly Jana Dagdagan (Stereophile's editorial coordinator), and AudioQuest communications VP (and former Stereophile staffer) Stephen Mejias smiled at me like characters from La Dolce Vita. ZZ Top's "Jesus Just Left Chicago" blasted the boogie. The sound of Bender's all-Gamut system—the center of this surreal, volume-pounding scene—was truly fascinating.

Along the room's long wall, GamuT's RS3i stand-mounted speakers ($20,990/pair) were getting their mojo workin' via the company's D3i dual-mono line-stage preamplifier ($8380), D200i dual-mono stereo amplifier ($13,990), and CD3 CD player ($7990), all connected via GamuT Reference interconnects, speaker cables, and power cords. Analog goodness was provided by a Pear Audio Blue Kid Thomas turntable with Cornet 2 tonearm ($7995), Pear Audio Blue Classic phono stage ($1995), Pear Audio external power supply ($1995), and a Transfiguration Proteus cartridge ($5,999). This mighty system provided gusto and glory, music bouncing off the walls with true force, unerring musicality, and heartfelt fun. I wanted more!

But I was on a quest for the absolute integrated amp. I asked Vamos if GamuT offered a high-powered model of such design. They do: the Di150 LE dual-mono integrated amplifier.

Design
GamuT's Di150 LE (for Limited Edition) is a Danish-built, 59.4-lb, aluminum-encased powerhouse that outputs 180Wpc into 8 ohms, 360Wpc into 4 ohms, or an-ear challenging 700Wpc into 2 ohms. The Di150 boasts a frequency response of 10Hz–50kHz, ±0.1dB—none too shabby! At its center is a circuit topology introduced by GamuT's founder and designer, Ole Lund Christensen.

In the early 1980s, GamuT made amplifiers for Denmark's professional recording studios. Forgoing the usual banks of transistors, which he believed only smeared the music, Christensen instead sourced massive negative-positive-negative MOSFET transistors used in industrial welding, using only one or two per rail. Eventually, GamuT sold these N-channel MOSFET amps to high-end devotees across Europe.

Michael Vamos led me deeper down the rabbit hole of N-channel MOSFET design: "Many amps use up to 48 transistors per channel, which creates a lot of sonic and signal compromises," Vamos claimed. "Whenever you use more than one transistor, they're never matched exactly, and they will sound different. When you listen, especially in the midrange, you will get a phase issue. The transistors aren't reproducing exactly the same in order to get all the power; they're slightly different. That will muddy the signal. But if only one transistor is reproducing the sound, then it will only reproduce the signal.

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"The GamuT MOSFET is ten times the volume of the biggest hi-fi transistor," he continued. "And they're both NPNs, which eliminates the difference of having a positive and a negative transistor. Each NPN is technically and sonically the same. That eliminates crossover distortion." (footnote 1)

Benno Meldgaard, GamuT's chief of design, wrote in an e-mail that "GamuT's single MOSFET is class-A/B design, biased to 14 watts class-A. This is to run the transistors at an optimum temperature that results in the best sound. GamuT also includes NPN bipolar transistors capable of putting out 25 watts of power which drive the huge [N-channel] MOSFET output transistors. And the two [500VA] toroidal transformers contribute greatly to the solid sound quality. [In] the GamuT design, both the negative and the positive rail have . . . MOSFETs that sound exactly [the] same, which results in a shorter pathway, with less components in the pathway, which gives a very low distortion of even-order harmonics."

Description and Setup
What couldn't be easily driven was my body as, one stairstep at a time, I upended and turned over—and over and over—the Di150's large wooden crate, until I reached my seventh-floor Manhattan crib. Said crate rolled into said crib, I then had trouble releasing the secret panel that would reveal precisely how to uncrate the Di150 LE. After much cursing and sweating on my part, the amplifier sprouted from its sarcophagus of roughhewn wood.

I removed the eight stainless-steel screws that affix the Di150 LE's heavy top plate to its enclosure and peered into its inner workings. Dominating the interior are two massive, Danish-made Noratel toroidal transformers, positioned next to four oversized RIFA capacitors. A handful of smaller Vishay capacitors populate two horizontal circuit boards. The long control rod of an Alps potentiometer ("a special low-resistance version, creating 10dB better signal-to-noise ratio," per Vamos) visually halves the amp's interior. Unusual for any amplifier, no Zobel network is used on the Di150's speaker outputs to keep the amp stable.

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Substantial but svelte, heavy-duty but manageable, the Di150 LE slid, with effort, into my Salamander rack, looking quite out of place below my green Shindo Laboratory preamp and power amp. GamuT recommends 100 hours of break-in, which I accomplished via Apple iTunes Shuffle. Thereafter, I left the Di150 powered on 24/7.

The Di150 LE may be a hulking machine, but I believe it would find its place in any décor. Its silver faceplate is offset by a black case—both formal and flashy—and dominated by a large volume-control knob at the center of its display. Flanking the display are two columns of four silver pushbuttons each: on the left, Balance 1, Balance 2, CD, and Dim; on the right, Tuner, Tape, HTH, and Mute. (A tiny toggle switch on the amplifier's rear panel enables HTH—presumably for Home Theater—mode, in which the Di150's preamplifier section is bypassed so that the user can insert a processor—or, according to Vamos, another preamp, the Di150 then functioning as only a power amp.) These controls, including Volume, are duplicated on a remote-control handset (included). Though rather cheap-looking, the remote handled all functions without a hitch—and unlike some fancier remotes, its batteries never fell out.



Footnote 1: A quasi-complementary output stage doesn't intrinsically eliminate crossover distortion, which requires the correct application of output-stage bias current. But the fact that the two N-channel transistors are by definition perfectly matched does, I believe, confer better open-loop linearity.–John Atkinson
COMPANY INFO
GamuT Audio
US distributor: GamuT Inc. (Audio Skies)
Los Angeles, CA
(888) 252-2499
ARTICLE CONTENTS

COMMENTS
mrkaic's picture

You get MUCH better performance from the Benchmark ABH2 for a quarter of the price of this thing. In my opinion, this GamuT amplifier is worth between $370 and $415.

Dcode's picture

Don't say it's too expensive. Just be honest. Say you can't afford it. It makes more sense.

mrkaic's picture

Dear Sir, what makes you so certain that I cannot afford it? Have you used some techniques worthy of Sherlock Holmes to deduce my credit worthiness? :))

Or are you just trying to deflect the attention from the undisputed fact that many much cheaper NAD amplifiers will perform just as well as the Gamut?

Dcode's picture

It's true though, isn't it?

darcman's picture

Trolls are everywhere, why even bother with a stupid comment you just embarrass yourself. If you looking in this price range, the Gamut Di150LE should be on every ones short list....looks great!!!

mrkaic's picture

A lot of mediocre (and sometimes even substandard) audio equipment these days is terribly overpriced. It takes a suspension of critical thinking (i.e. subjectivism) to justify purchases of such stuff.

Sad, but true.

darcman's picture

The comment was still stupid. The price of the Gamut is right in line with the top offerings from others. It would be nice if it was $5k cheaper but it isn't. If they were able to sell it for $415 they would put EVERYONE out of business...True Story LOL

mrkaic's picture

...is the price of this stuff and comments that defend such outrageous prices by claiming that this is a "top offering". By what measure is this top level?

You can get an amplifier that will have comparable measured characteristics for a fraction of the price of this one -- NAD amplifiers come to mind. Is NAD top level too?

johnnythunder's picture

Look, I can't tell you what you can and can't afford as far as listening. I love reading reviews of the most expensive and the best valued components in an attempt to understand the myriad of possibilities available to me as a listening experience. I read car magazines for their reviews of Bentleys and Teslas even though I drive a 1999 car with over 200k miles on it. Ditto with cooking and wine publications. I don't get angry that a certain Barolo costs over $100 and don't demand a blind comparison with lesser expensive wines. If one wants to go through life ANGRY that certain products are beyond their reach and shitting on the joy of others go for it. I think you're missing the point that these magazines are here to NOT be Consumer Reports. They exist to tantalize and offer some sort of aspirational guide to what is out there. Yes our hobby is more expensive than it used to be but I get enjoyment from my 10k system that has been assembled over the years from reading about equipment that the reviewer has illuminated as having appeal to me. One description of a midrange as "thin" or a "hyper detailed tweeter" will send me scurrying to the warmth of my Luxman amp and Jean Marie Reynaud speakers. But I don't get angry that others like that sound. So enjoy your NAD. There's nothing wrong with it. But don't demean the GAMUT because its a luxury product.

mrkaic's picture

Dear Sir:

First, let's get one thing out of the way quickly -- I am not angry at or envious of people who buy overpriced amplifiers. I do pity them though, because I see many of them as deniers of engineering and scientific facts. Instead of buying their overpriced trinkets, "audiophiles" could more usefully spend their money on a few courses in electrical engineering to help them actually understand their cherished hobby.

Second, judged by your frequent use of capital letters, you just might be the angry one. :)

Finally, your conclusion that I have a NAD is wrong. But I might remedy that, they make fantastic products.

johnnythunder's picture

Your term "overpriced trinkets" immediately establishes your pejorative tone with regard to expensive audio components or tweaks or whatever. Your statement/opinion, "In my opinion, this GamuT amplifier is worth between $370 and $415." is pretty ludicrous. I don't pity deniers of engineering and scientific facts when it comes to certain aspects of audio engineering. This isn't global warming. I read for years in Consumer Reports that all CD players sounded the same. I don't "buy" the claims of many tweaks but is it false advertising? Maybe. I really don't care. People can spend money on what they want to. I'm a little disappointed that a well written review of a well manufactured product is tossed away by an insipid argument and it's an argument that has a "rain on my parade" tone. I would enjoy whatever lower priced component you have and allow any future purchasers of Gamut products to enjoy their purchases based on Ken's review.

mrkaic's picture

I have little patience for science deniers. While audio is not global warming, the underlying mechanism of denial is quite similar.

RaimondAudio's picture

Sorry...you can comment about the technical stuff, but you can not comment about the price. Why ? Because we are not in a comunist economy. We are in a free economy. That it is the most important thing. Do not like the price ? Ok, do not buy it, but please, do not atack the free economy.

What about 2%-THD of the tubes amps ? What we will do with them ? What it is the right prices for them ? 10$ ?

mrkaic's picture

Are you trying to censor me? I am allowed to comment on anything I want.

I am glad you talk about free markets. In a competitive market the price is equal to the marginal cost. What is the marginal cost of this amplifier? 2 mosfets for $2 each, a few other BJTs for $10 combined, a few wires, worth less than $1, some capacitors, generously priced at $50, and the enclosure for $40. Am I missing any parts? Maybe a few diodes to bias the transistors. Add some solder, equipment depreciation, and a few hours labor for assembly and the sum is still less than my suggested price of $375. But let's say that with shipping and handling you can get to $375. If they sell if for $415, they will make 10% profit, which is pretty decent for an amplifier with not exactly ground breaking measured performance.

RaimondAudio's picture

:-) Noo. I do not want and I can not censored you. I just spoken about free markets. The profit could be any percent: 1%, 10%, 10.000%. That is tha life in a free markets. Best regards.

Dcode's picture

You obviously have not gone into business for yourself and looked at all the costs involved in owning and operating a company and what real overhead is. Workman's comp, insurances, marketing, legal--let alone what it takes to test and bring a product to market. Testing, re-testing, trail, error, sourcing parts, training staff, fielding lawsuits from freeloading employees looking for a quick buck, getting staff to actually work and care, quality checks on outside parts provided... If you went to a factory and sat down with the owner of a HiFi company and saw how many hours it takes and total devotion with no guarantee of retirement or financial security, you'd shut right up and go back to your cubicle and put your headset back on.

mrkaic's picture

I actually did go into business and co-owned two companies that made decent profits, thank you very much.

It would be nice if you could focus on the amplifier, not on what I can or cannot afford or if I was ever in business for myself.

It seems that you enjoy going personal and that misses the point of this forum.

Dcode's picture

Made (past tense) good profits. Reminds me of The Fox and the Grapes--one of the Aesop's fables. The story concerns a fox that tries to eat grapes from a vine but cannot reach them. Rather than admit defeat, he states they are undesirable (or too expensive).

The "too expensive" or "no better than something less expensive" cry in the comments of an audio blog is so played out.

mrkaic's picture

Your unwillingness to focus on the amplifier and to keep slinging personal insults is also played out. I am now convinced you have little to no understanding of audio.

dissily mordentroge's picture

Too often I've read angry discussions of the kind above. What is it about audiophiles (audiophools?) that appears to make so many outraged at the enjoyment of others and why are these differences so often expressed in a vitriolic manner with all the maturity of a six year old? An unanswerable question I suggest short of abducting a large sample of such persons from an audio show, isolating them from their toys and subjecting them to several years of psychoanalysis and blind listening tests.
There are so many unanswerable questions in this context. Take for instance the question of why results of clinical hearing tests given audio reviewers aren't published along with their reviews.
My take on the Gamut V Cost controversy? OK maybe it's not worth sum total of research,production, advertising and material costs involved but why get angry if you imagine purchasers are either too deaf or too rich to make what you think is a rational purchase? Maybe we're back at that other hoary old question " Do we really know if laboratory test results tell us everything we need to know to characterise how a component is heard by EVERY listener?
Which leads me back to that other elephant in the room. Can we ever be sure any audio reviewer/audiophile will hear the same piece of equipment the way we do?

mkwglyg's picture

After reading this review, I must admit I'm aghast! Shocked!
It says the Gamut Di150 sounded flat using a standard power cord but suddenly becomes fantastic when using that isotek power cord. Wow! Seriously? Wow!
Does the isotek powercord possess some special superpowers that can raise the dead?
C'mon! if a 10grand equipment cannot even sound right using a standard power cord, something is seriously wrong with it, no cable however magical is going to save it, period.
However, if what the reviewer said is true, then i must get that isotek powercord for all my equipment, cd players, preamp, amps, everything! But surely not the Gamut Di150 which i am highly suspicious of judging from this review.

Get that isotek power cord!

Note: After doing a search on user opinions on the isotek cable, some claimed that its a waste of money. Now I'm totally lost.

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