mulder01
Headphoneus Supremus
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Hmmm, has anyone bought one of these systems?
Sonoma Model One electrostatic headphone system
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Not that I'm aware of, which is why I had asked @Music Alchemist (again) being I had seen his gear for sale, and he posted the review as if he was interested.
Music Alchemist
Pokémon trainer of headphones
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I buy, sell, trade, and even return gear on a frequent basis. Simply posting a review link does not imply I am interested in buying it at this time; I merely shared it for the benefit of others.
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As I mentioned, I thought you were interested, that's all.
JimL11
1000+ Head-Fier
Interesting to speculate on what the market is for this. Here is a system that is clearly aimed at relatively affluent audiophiles, but audiophiles as a general rule don't buy all-in-one systems that cannot be upgraded - this is a combination where the headphone and amp are dedicated to each other without any obvious path to upgrade in the future.
Indeed the Sonoma isn't really for the head-fi "hobbyists" unless it was hands-down the best sounding headphone on the planet. For me this is a hobby and mixing-and matching gear is part of the fun. If you want a set-it-and-forget-it setup, the Model One isn't a bad option at all. Akin to the Stax "combos".
The amp unit is overbuilt and extremely nicely made, the headphones themselves had what I would call "we're new to making headphones" teething issues with fit and finish and comfort. They sounded quite nice if not a little too polite for my own tastes. I'd be interested in a rev.2 with a better head band design.
Just my 2¢ after listening at a couple of noisy canjams.
The amp unit is overbuilt and extremely nicely made, the headphones themselves had what I would call "we're new to making headphones" teething issues with fit and finish and comfort. They sounded quite nice if not a little too polite for my own tastes. I'd be interested in a rev.2 with a better head band design.
Just my 2¢ after listening at a couple of noisy canjams.
FWIW, my review will be out in a few weeks. I really liked them!
JimL11
1000+ Head-Fier
Well, Stax isn't quite the same in that there are a few third party amps which IMHO sound better than the Stax amps, so there is some upgrading to be done. As far as the Sonoma amp, the case may be "overbuilt" but given its form factor and the fact that it is single-ended, it cannot have the kind of power that, say, a KGSS Carbon or BHSE have, otherwise you could fry eggs on it.
JimL11
1000+ Head-Fier
@MacedonianHero, if you haven't sent it back yet, could you possibly measure the power consumption of the amp using a Kill-A-Watt or some other cheap power meter? This can give us some idea of how much power the amp has to drive the headphones.
If I remember correctly it ran warm but not hot. The manual lists the power supply specs so maybe that can help you ballpark the maximum draw it would ever need.
"External: AC Adapter Model No. GPE072D-240270W
24 Volt DC, 2700ma 60 VA, fixed frequency, class B-compliant SMPS Internal: fully isolated, ultra-low-noise linear regulation."
So like 65W ceiling from the supply.
"External: AC Adapter Model No. GPE072D-240270W
24 Volt DC, 2700ma 60 VA, fixed frequency, class B-compliant SMPS Internal: fully isolated, ultra-low-noise linear regulation."
So like 65W ceiling from the supply.
mulder01
Headphoneus Supremus
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hmm how much power is normally consumed to drive a normal pair of electrostatic headphones? Because I mean, at normal listening levels, even the most inefficient planar/dynamic headphones on the market would be not even pushing 1w.
JimL11
1000+ Head-Fier
According to Sonoma's website, the outboard power supply "is capable of delivering about 3.5 times the maximum power the amplifier is designed to draw under steady-state conditions." Since it is specified at 60VA (i.e. 60 watts), this means that the amp draws about 18 watts, or 9 watts per channel. This is consistent with @Muniarc's observation that the amp ran warm but not hot. A 60 watt amp in that size enclosure would probably allow you to fry eggs on top, Since the input and driver stages draw some power, figure the output stage draws 8 watts/channel. Now the amplifier is "single-ended, discrete FET Class-A", so its theoretical maximum efficiency is 25%, which means it can perhaps deliver 2 watts/channel to the headphones (BTW, for a single ended amp, the power draw is pretty much constant). Doesn't sound too bad, right?
Well, the Stax amps (SRM006,007 and 727) run roughly +/-350 volt PS and 5-8 mA per device, so the output stage burns 14 to 22 watts/channel. But they are all push-pull, so the theoretical maximum efficiency is 50%, which means they could deliver 7-11 watts. Take a KGSS Carbon at +/-400 volts and 16-20 mA per device, the output stage draws 25-32 watts, with theoretical maximum power delivery at 12-16 watts.
So, we can see that the Sonoma has significantly less maximum watts out (2 watts/channel) vs the Stax amps (7-11 watts) or a KGSS Carbon (12-16 watts). This is a fairly wide range , but remember that power demands are exponential. Listen at twice the subjective loudness and you require roughly ten times the power. Now, unlike power amps for speakers, where you can drive the amps to clipping, it is much less likely that you will do this with electrostatic headphone amplifiers. However, the issue here has less to do with clipping than with headroom. No amplifier sounds its best when driven near its limits.
So, how much power does an electrostatic headphone require? According to an old post by Kevin GImore, he has measured the SR007 drawing up to a watt of peak power - he didn't specify if this was both channels or one channel. Now, obviously this depends a great deal on how loudly you listen, the SR007 is considered one of the less efficient stat, but it gives us a baseline. The missing factor here is the efficiency of the Sonoma headphone, and remember that a mere 3 dB difference in efficiency can double or halve the power required to achieve the same SPL
Subjectively, apparently the Sonoma headphone plays loudly enough for most, but as Tyll's InnerFidelity review makes clear, crank it up and it hits its limit, which is what one would expect with its relatively limited power output.
Well, the Stax amps (SRM006,007 and 727) run roughly +/-350 volt PS and 5-8 mA per device, so the output stage burns 14 to 22 watts/channel. But they are all push-pull, so the theoretical maximum efficiency is 50%, which means they could deliver 7-11 watts. Take a KGSS Carbon at +/-400 volts and 16-20 mA per device, the output stage draws 25-32 watts, with theoretical maximum power delivery at 12-16 watts.
So, we can see that the Sonoma has significantly less maximum watts out (2 watts/channel) vs the Stax amps (7-11 watts) or a KGSS Carbon (12-16 watts). This is a fairly wide range , but remember that power demands are exponential. Listen at twice the subjective loudness and you require roughly ten times the power. Now, unlike power amps for speakers, where you can drive the amps to clipping, it is much less likely that you will do this with electrostatic headphone amplifiers. However, the issue here has less to do with clipping than with headroom. No amplifier sounds its best when driven near its limits.
So, how much power does an electrostatic headphone require? According to an old post by Kevin GImore, he has measured the SR007 drawing up to a watt of peak power - he didn't specify if this was both channels or one channel. Now, obviously this depends a great deal on how loudly you listen, the SR007 is considered one of the less efficient stat, but it gives us a baseline. The missing factor here is the efficiency of the Sonoma headphone, and remember that a mere 3 dB difference in efficiency can double or halve the power required to achieve the same SPL
Subjectively, apparently the Sonoma headphone plays loudly enough for most, but as Tyll's InnerFidelity review makes clear, crank it up and it hits its limit, which is what one would expect with its relatively limited power output.
Music Alchemist
Pokémon trainer of headphones
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Power consumption and output power are two different things. For example, the Schiit Magni 2 Uber can output up to 1.2W RMS per channel at 50 ohms, but its power consumption is 5W.
Electrostatic headphones use hundreds of volts, but very little current, so maximum output voltage instead of output power is listed for the amps. They also usually list the power consumption.
Here are some of those specs, for reference. The thread links are for voltage and output stage current. The specs I list under that are power consumption.
Note that the voltage specs on that thread are listed peak to peak rather than RMS. It's important to know which spec you're looking at, since they can differ based on that. (For example, the STAX SRM-T8000's maximum output voltage is 470Vrms or 1330V p-p.)
https://www.head-fi.org/threads/electrostatic-amplifiers-voltage-ratings.582518
https://www.head-fi.org/threads/electrostatic-amplifiers-voltage-ratings.582518/#post-7925458
HeadAmp Blue Hawaii Special Edition: 180W
Woo WES: 118W
STAX SRM-T8000: 95W
HeadAmp Aristaeus: 60W
STAX SRM-007tII: 55W
STAX SRM-006tS: 49W
STAX SRM-727II: 46W
STAX SRM-353X: 30W
STAX SRM-252S: 4W
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