Sonoma Acoustics Model One Electrostatic Headphone and Amplifier System Measurements

Click on graphs image to download .pdf for closer inspection.

Raw frequency response plots show the headphone has stable bass response in numerous positions; the strong clamping force may play a role here. Overall frequency response is extraordinarily similar to the Harman Target; in fact better in some ways. I like that it has a linear slope after the 3.5kHz peak as the Harman target has a curved fall off leaving a little too much energy in the 3-10kHz range. Bass boost is mild and extends beautifully. Aside from the bass distortion at high levels, the Model One has spectacular bass response.

Also note, other than the strong feature between 10-12kHz, the plot is remarkably free of strong irregularity. Response is even and smooth for the most part. Interestingly, the plot between 1-3kHz is a bit rough as I move the headphones around. Sound has a half-wavelength of 4.5" to 2.25" at these frequencies...just about the right distance to see interference from the spacing of the cells of the diaphragm.

30Hz square wave has beautiful shape with a small shoulder in front for warmth, and a beautifully linear wave top. Wave top remains nicely above zero for its entire length echoing the really good bass extension on the FR and as heard.

300Hz square wave shows a quick and appropriately high initial rise and overshoot. The following ring is low in level and expected; the following waveform top is very gently rising, which is good. The noise level is a little excessive and quite random, indicating to me numerous mild resonances at multiple frequencies. It'll be interesting to see the CSD plots over at SBAF to see if multiple, mild ridges that quickly fade appear.

Impulse response is likewise quick and authoritative with subsequent noise longer lived than desirable, but at a low level and quite random. I suspect what we're seeing is what I called "hazy" and "foggy" in the review. It's low, but it's there.

The THD+noise is certainly somewhat off-putting. This headphone doesn't like being run at 100dBspl. All I can say to add to what I've already said is that it doen't sound nearly as bad as it looks a normal listening levels.

This headphone is open and has little isolation.

Sonoma Acoustics

Tyll Hertsens's picture
Thanks, Suuup! got a little thump back into estats...long as you don't crank it.
Suuup's picture

Another interesting comparison is This is harman-compensated.

Tyll Hertsens's picture
...damn...that's pretty good.
JimL's picture

Actually, I believe that -70 dB is 0.03% rather than 0.05%. Both are very good.

JimL's picture

Hm, -30dB at 105 dB is 3% 2nd harmonic distortion.

-40 dB = 1%
-50 dB = 0.3%
-60 dB = 0.1%.
-70 dB = 0.03%
-80 dB = 0.01%
and so on - actually, each 10 dB represents Sq rt of 10 decrease = 0.3162x

MRC01's picture

Correct. In case anyone wants to compute it for himself, the formula is: DB volts = 20*log(ratio). The log is base 10, so it's easy to see every factor of 10 is 20 dB. For power it's DB power = 10*log(ratio), so every factor of 10 is 10 dB.

The reason the formula is different for V versus P is for consistency. This way, an X dB difference in voltage creates an X difference in power. If the formulas were the same, an X dB difference in voltage would make a 2X dB difference in power. That's because doubling the voltage doubles the current (since V=IR), which quadruples the power (since P=VI).

GearMe's picture

Your description of the sound reminds me how I felt a long time ago with the Quad ESL-57s compared to the other speakers I owned. For certain types of acoustic music they just had "it"...sounding more real to my ears than any other speakers I've owned. That said, their dynamic range sucked enough that I eventually got rid of them. In hindsight, a dumb decision. ;-)

ab_ba's picture

"Take your average $4000 headphone..." Love it.

Magoo's picture

WOW! $5K for a HP with limited Bass and grainy HF? The DAC has the infamous glare producing ESS Sabre?

Not for me at least...Thanks for the review!

Tyll Hertsens's picture
Seriously, I wouldn't say it had any glare or grain, just a bit hazy. Limited bass level though, for sure.
detlev24's picture

"[...] if you don't throw at least another $4000 in amp and DAC at it you're probably wasting money with underperforming very expensive gear."

That sounds like a commercial for unreasonable expensive gear. Just one example: Take the Focal Utopia, add 50% of its price (~ $2000) and you have it attached to a state-of-the-art amp/DAC, the RME ADI-2 Pro. It will absolutely not be underperforming on this gear and you could even save some bucks by choosing a different combo; if you are not in need of the built-in ADC and EQ.

Of course, you can spend as much (more) money as you want if you subjectively prefer, e.g., the euphonic distortion of tube amps (which could be added to any neutral gear by effects, btw.) or like to have a "design object" to also please your visual stimuli. Again, that is an option but certainly not a necessity to fully power your headphones!

elmura's picture

Whilst $5k ain't cheap, it's within reach of high-end systems, and certainly cheaper than LCD-4 / Utopia etc systems. The fact that the system is tuned to work optimally together using DSP EQ means buyer doesn't need to worry about system synergy, trial and error of different amps / dacs etc. And, I'd bet they will be sending DSP updates in future. I'd like the ability to tune the DSP EQ to suit different hearing (or taste).

I'm interested in this product's future.

MRC01's picture

It seems more like a science project than a product. I love Tyll's open minded optimism & enthusiasm, and as an engineer I respect what they did, but why they chose this kind of driver mystifies me. It seems like they picked an inherently poor driver and did some real brain sweat and engineering to make it sound less bad, ending up with a very expensive product with mediocre performance. I can't help but think that if they applied that same engineering effort to a conventional or ortho driver it would be truly astounding.

Magoo's picture


When will you report on these latest Grado HP's? $2700 and yet built like $30 Hp's?


solrage's picture

I had high hopes for these. $5k for an all-in-one system synergistically designed to work well with each other isn't really outrageous given the price of high-end headphones/amps/dacs out there these days. The frequency response is definitely on point, but those distortion figures make this a no-go for me. On days where I don't plan to listen for very long I like listening >90dB, and even on days where I keep my average level <85dB, a lot of music I listen to--especially orchestral usic--has dynamic peaks over 100dB, so being able to play clean loudly is a prerequisite. Oh well, guess I'll just have to see how the LCD-4/Utopia fiasco turns out... or maybe just wait until some company finally puts out a great headphone that ticks every box. Until then, I'll remain relatively happy with my HD800s, HE-6, and LCD-X combo.

heymamahey1990's picture

People need to make use of what they have. - Steven C Wyer

harry56's picture