Gryphon Essence Mono power amplifier Measurements

Sidebar 3: Measurements

I tested the Gryphon Essence with my Audio Precision SYS2722 system (see the January 2008 "As We See It"). I preconditioned the amplifier by operating it with class-AB output-stage bias at one-third the specified power into 8 ohms for an hour. At the end of that time, the top panel's temperature was 88.3°F (31.3°C) and that of the side-mounted heatsinks 90.4°F (32.4°C). Repeating the preconditioning with class-A bias after letting the amplifier cool down resulted in a slightly higher heatsink temperature, 92.1°F (33.4°C). The Essence monoblock easily has sufficient heatsink capacity for its output power.

The Gryphon's voltage gain into 8 ohms measured 30.7dB with both output-stage bias conditions, and the amplifier preserved absolute polarity (ie, was noninverting), the XLR input jack being wired with its pin 2 positive. The input impedance was close to 10k ohms from 20Hz to 20kHz. Though this is half the specified 20k ohms, it is still sufficiently high not to cause compatibility problems with tube preamplifiers.

The Gryphon's output impedance in class-A was higher than the specified 0.015 ohms, at 0.26 ohm at 20Hz and 1kHz and 0.28 ohm at 20kHz. (These values include the series impedance of 6' of spaced-pair loudspeaker cable.) The output impedance was slightly higher in class-AB, at 0.29 ohms at 1kHz. Nevertheless, the modulation of the amplifier's frequency response, due to the Ohm's law interaction between this source impedance and the impedance of our standard simulated loudspeaker, was small, at ±0.2dB (fig.1, gray trace). The response into an 8 ohm resistive load (fig.1, blue trace) was flat to 20kHz and down by 3dB at 170kHz, which correlates with the Essence's superb reproduction of a 10kHz squarewave (fig.2). Commendably, there was no overshoot or ringing with the squarewave response. Into 2 ohms (fig.1, red trace), the response was –0.2dB at 20kHz and –3dB at 90kHz.


Fig.1 Gryphon Essence, frequency response at 2.83V into: simulated loudspeaker load (gray), 8 ohms (blue), 4 ohms (magenta), 2 ohms (red) (0.5dB/vertical div.).


Fig.2 Gryphon Essence, small-signal 10kHz squarewave into 8 ohms.

Measured with the input shorted to ground, the amplifier's unweighted, wideband signal/noise ratio was an excellent 86.5dB ref. 1W into 8 ohms, this ratio improving to 95.9dB when the measurement was restricted to the audioband, and to 100.8dB when A-weighted. This is a quiet amplifier. Spuriae at the 60Hz power-supply frequency and its harmonics were very low in level but varied with the output-stage bias. The spuriae at 60Hz and 180Hz were highest in level with class-A bias, at –104dB and –110dB ref. 1W into 8 ohms (fig.3, red trace), and were even lower in level with class-AB bias (blue trace).


Fig.3 Gryphon Essence, spectrum of 1kHz sinewave, DC–1kHz, at 1W into 8 ohms with class-A bias (red) and class-AB (blue) (linear frequency scale).

The Essence's manual specifies the amplifier's maximum power as 55W into 8 ohms, 110W into 4 ohms, and 220W into 2 ohms, all equivalent to 17.4dBW (footnote 1). Using our definition of clipping, which is when the output's percentage of THD+noise reaches 1%, the Gryphon didn't quite meet its specified powers, clipping with a 1kHz signal at 53W into 8 ohms (17.24dBW) with both class-A bias (fig.4) and class-AB bias (fig.5). In both bias conditions, the THD+N was very low at powers of a few watts. Into 4 ohms, the Essence clipped at 101W (17.03dBW), but the THD+N was lower at low powers with class-A bias (fig.6) than with class-AB bias (fig.7). The Essence didn't quite meet its specified power into 2 ohms, clipping at 182W (16.58dBW, fig.8, class-A; fig.9, class-AB). However, it is relevant to note that I don't hold the AC wall voltage constant when I test an amplifier's clipping power.


Fig.4 Gryphon Essence, class-A bias, THD+N (%) vs 1kHz continuous output power into 8 ohms.


Fig.5 Gryphon Essence, class-AB bias, distortion (%) vs 1kHz continuous output power into 8 ohms.


Fig.6 Gryphon Essence, class-A bias, distortion (%) vs 1kHz continuous output power into 4 ohms.


Fig.7 Gryphon Essence, class-AB bias, distortion (%) vs 1kHz continuous output power into 4 ohms.


Fig.8 Gryphon Essence, class-A bias, distortion (%) vs 1kHz continuous output power into 2 ohms.


Fig.9 Gryphon Essence, class-AB bias, distortion (%) vs 1kHz continuous output power into 2 ohms.

I measured how the THD+N percentage changed with frequency at 12.65V, which is equivalent to 20W into 8 ohms, 40W into 4 ohms, and 80W into 2 ohms, which are all approximately 4dB below the clipping powers into these loads. The THD+N was very low in the midrange into 8 and 4 ohms with both class-A bias (fig.10, blue and red traces) and class-AB bias (fig.11, blue and red traces), but rose into 2 ohms (red traces). There is the usual increase in THD+N in the top audio octaves, due to the circuit's limited open-loop bandwidth. (There is less gain margin available for negative feedback at high frequencies.)


Fig.10 Gryphon Essence, class-A bias, THD+N (%) vs frequency at 12.65V into: 8 ohms (blue), 4 ohms (magenta), 2 ohms (red).


Fig.11 Gryphon Essence, class-AB bias, THD+N (%) vs frequency at 12.65V into: 8 ohms (blue), 4 ohms (magenta), 2 ohms (red).

With class-A bias, the Gryphon Essence's distortion was predominantly an equal mix of the subjectively benign second and third harmonics (figs.12 and 13), each lying at –73dB (0.025%) ref. 20W into 8 ohms. Higher harmonics are all much lower in level. With class-AB bias, the second harmonic was the highest in level, at the same –73dB (fig.14), but there were now more higher-order harmonics present. When the Essence drove an equal mix of 19 and 20kHz tones with a peak level of 20W into 8 ohms (fig.15), the second-order difference product at 1kHz lay just above –80dB (0.01%) in both bias conditions with higher-order intermodulation products a little higher in level, at –70dB (0.03%).


Fig.12 Gryphon Essence, class-A bias, 1kHz waveform at 20W into 8 ohms, 0.0385% THD+N (top); distortion and noise waveform with fundamental notched out (bottom, not to scale).


Fig.13 Gryphon Essence, class-A bias, spectrum of 50Hz sinewave, DC–1kHz, at 20W into 8 ohms (linear frequency scale).


Fig.14 Gryphon Essence, class-AB bias, spectrum of 50Hz sinewave, DC–1kHz, at 20W into 8 ohms (linear frequency scale).


Fig.15 Gryphon Essence, class-A bias, HF intermodulation spectrum, DC–30kHz, 19+20kHz at 20W peak into 8 ohms (linear frequency scale).

The Gryphon Essence performed very well on the test bench.—John Atkinson

Footnote 1: The website, but not the manual, specifies slightly higher maximum output powers in class-AB.

Gryphon Audio Designs ApS
US distributor: On a Higher Note
PO Box 698
San Juan Capistrano, CA 92693
(949) 544-1990

tonykaz's picture

So, they rely on thier collection of first & second generation Tape --- "NO CD or LP comes close" according to the Company's Mission Statement. Hmm

This outfit makes a nearly full range of home Audio gear with the exception of Loudspeakers or Record Playing Gear. Their GRYPHON ETHOS CD made it to the front Page of Stereophile!!

Seems this Company's products fall into the Accuracy camp. ( I prefer the 'Better-Sounding' gear that's so thick and murky that it's not at all transparent )

This outfit's products are way too pricy for me but I haven't seen any Northern Eureopean Audio Gear that I didn't seem to love.

I'd like to see their Factory and meet these people.

Tony in Venice

Ortofan's picture

... a lower output impedance and lower levels of distortion.
Try, instead, a Rotel Michi S5 or M8.

tonykaz's picture

I'm fighting against the Current.

I can't support Domestic Outfits that outsource to China.

I can accept Chinese Outfits and Brands.

Companys that source China dilute their Brand, diminish re-sale values, erode future service possibilities and generally lower the overall quality Bar for the entire industry.

Sourcing in China is trading a fast buck for a slow train wreck.

Tony in Venice

ps. I do like the Chinese outfits that operate here in the US and sell their Brand in the US

Ortofan's picture

... presently use and where was it manufactured?

tonykaz's picture

I buy some of the Gear reviewed here in Stereophile. Mr.HR, Audiophiliac and now Mr.KM seem like reliable reporters of gear. I buy and then sell. ( Mr.JA1 has always confirmed gear beautifully, he is probably the Greatest resource of Higher Authority confirmations EVER!!!, where would we be without him? , he alone is the great establisher )

I also buy Estate Sale Audiophile Gear for Resale.

I tend to love simple tube gear for myself i.e. Schiit Valhalla with Russian Tubes is glorious as a Pre and headphone amp.

I continue to cherish horns i.e. Klipsch and the simple Cardboard ones I build myself.

I'll buy any and all Audiophile gear I encounter. I'm buying right, rebuilding or refurbishing where needed, cleaning, evaluating and then selling. ( I've a tech that tunes amplification )

I have consistent buyers in Asia that seem to love USA & European Gear ( for dam good reasons ).

I'm mostly a Shirt Pocket Audiophile type, my wife is an Ordained Minister that now uses our home as her base of operation. I'd love to have our home Ether filled with wafting therapeutic music.

Although I don't do much buying of Audiophile loudspeakers, I do have quite a few smaller ones waiting for selling.

I'm not any sort of dealer for any Company, I sell used gear only, mostly Overseas to Japanese speaking Customer Base, I have a Japanese speaker handling communications.

Audiophile stuff is a curious hobby for me, I and local friends get to "hands-on' review a wide range of unique gear. Buying & Selling easily finances my expenditures. There is a buyer for every quality Audio gear.

I've discovered : Reviewers without a PS Audio Powerplant write defective reviews, it can't be helped !

Tony in Venice

ps. I'm retired and have taken up wood working along with chasing everything I never had time for. I won life's lottery some-how!

georgehifi's picture

This is what an amp with real drive can achieve, would have been interesting to see what the 1ohm wattage figure was.
And at least they didn't understate the 8ohm figure just to make the 4ohm look good, like many do, especially Class-D's

53W into 8ohms
101w into 4ohms
182w into 2ohms

These to me spell the reincarnation of the 20w Mark Levison ML2 Monoblock's!!

Cheers George

CG's picture

I am confused.

Not the first time, obviously, so I am familiar with the feeling.

Let me quote from the On A Higher Note website with regard to this and the stereo version of the Essence amplifiers:

"• Zero global negative feedback"

So, either something in the measurement explanation is askew or the cited web page is.

This review brings up a great topic. Jason's observations are that operating in Class A is way better for sound than in Class A/B for this amplifier. That's not anything new, and I don't question his take on this even a teeny bit. It's interesting to read his description of just how much better high bias operation is in practice.

The question then becomes, "Just how much Class A power do you really need for best sound quality?" I don't know the answer, and am not suggesting that I have any great insight into this. But, I'd sure be interested in learning.

The Gryphon gives 7 watts in Class A/B mode according to the designer, who I presume would know. Based on the AC mains consumption and a quick minute or two with a calculator, it appears that indeed the amplifier always runs in Class A mode up to clipping down to about 3 Ohms load impedance or thereabouts when set to high bias mode. (With Jason's Wilson loudspeakers, that means that the Gryphon amplifier rarely ever operates outside of Class A operation, and then just barely in part of the bass frequency band.)

So, pure Class A is great, at least in this case. Seven watts of Class A operation and the rest in AB may not be so hot. (Ha!) Is there a middle?

OT, some: I admire Jason's willingness to sacrifice his body for the sake of better sound and a better review. I hope he's recovered by now.

tonykaz's picture


tonykaz's picture

I just happened to see you discussing things Audio, for nearly two hours.

Your verbal descriptiveness is levels better than what I'm reading here in print. I'm complimenting!

Each of your subjects got a full covering of relative context.

and, you ( I'm delighted to notice ) are not a bull-shitting promoter or defensive. I felt that you were insightful, sincere, curious, genuine and honest.

I might caution you about we Audiophile's drifting into "Audiophile Nervosa", a condition I ( and my Psychologist ) work to keep at bay, phew . I'll I can prove that the better a Music System becomes, the more it needs constant improvements.

I, like Mr.HR, have owned and sold stratospheric quality audio gear. It's an endless rabbit hole. As the Audiophiliac reveals -- it's for the people who's rugs cost more than the Audio Gear & for people that don't read Stereophile.

20 year Forecast ? thats infinity. None of us have a clear vision of the end of 2021, for gods sake. But, I'd have to say that Mr.HR's final comments (of that podcast) were the clearest vision we have of our music industry's future.

Mr.MF didn't say but revealed that the 33.3 people can't press enough to keep-up but that still doesn't seem profitable enough for SONY to get back into the vinyl business. 33.3 Players cost a fortune!, Arms cost a fortune!, fragile phono cartridges cost a fortune!, 33.3 Records cost a fortune!, the Wooden Storage Shelving systems and residential space cost a fortune! And it's all Fossil Fuel based Music Storage i.e. Dinosaur Bones ( as any child will tell you ). Our Mr.MF also reveals that he won't ever listen to records he already owns, too many-too little time.

Audiologists will reveal decreases in ear sensitivity of lower and higher frequencies as we age. I think it's a problem that Sennheiser Headphones and Equalising will cure. A person can't bluff their way out of it. I've been tuning my synapses for some relief, its a deteriorating condition. My wife tends to yell because her hearing is defective, it seems.

All is well Mr.JS

You belong in front of the Camera.

Tony in Venice

Jason Victor Serinus's picture

I've actually been in front of the camera many times. One of the earliest was on The Tonight Show with some unknown guy they were trying out as a possible replacement for Johnny. His name was David Letterman.

tonykaz's picture

You struggle with the same darn things that plague all of us, it shows thru visually.

You could interview fascinating and informative people for solutions to your little issue, which is also all of our issue.

You could be talking to that Cary guy in N.C., the PS Audio Paul about things, you could call up anyone and do a YouTube Video Series. You are Stereophile and you are fresh enough not be a know-it-all, folks will feel like they can talk without getting stepped on.

Audio people need to get their message out, You are a viable channel to do that, you will have Steve G's type of success with 159,000 Subscribers. ( or more )

Tony in Venice

Ortofan's picture

... none of them is anywhere near the performance level of the units that had the Biotracer tonearm.

A decent analog disc player doesn't have to cost a "fortune".
The price of the AR turntable and Stanton cartridge I started out with a few decades ago would equate to about $1,200 today.
For that amount one can now buy a Technics SL-1500C, which includes an Ortofon 2M Red cartridge.

tonykaz's picture

There are enough excited Vinyl participants to keep Chad going strong, at least for now.

Globally, Chad has an ever increasing clientele, perhaps.

The UK has just started administering a Vaccination which is hoped to free us all from our home prison and hobby time. Nearly everyone needs to recover from the financially bad year of 2020. Fingers crossed !

Still, folks are reporting their streaming experiences in a very positive manner. Our reviewers are admitting things like they were late to start Streaming and that streaming is changing the game. Mr.Fine is reporting high sound quality from the streaming services.

So, while the very nice Technics turntable has price within reach, streaming is far more accessible and affordable. ( I think ). The 20 year future will probably have us looking back and wondering how we coped with walls of Vinyl Records ??? ( I wonder how I coped back in 1985ish )

I'm waiting for the First Review of an Audiophile product done with streaming only, who will be the first? I'm betting on Mr.HR but that beyond clever Mr. Micallef might just sprint ahead and shock us all!

Tony in Venice

rjel1976's picture

"The input impedance was close to 10k ohms from 20Hz to 20kHz. Though this is half the specified 20k ohms..."
The stereo version is specified at 20k ohms. The monoblocks you tested are specified at 10k ohms (and measured accordingly).

"The Gryphon's output impedance in class-A was higher than the specified 0.015 ohms"
Again, this is the spec for the stereo amp. The monoblocks are specified at 0.0075 ohms.

AnalogueFan's picture

No Slew Rate, no Damping Factor revealed.?