HIFIMAN Susvara Headphone Review

[usern]

Note: the continuous power rating of the HD 800 S is 0.5W, the AHB2 will be able to deliver 2.2W continuous.

So it most likely will break before reaching 134 dB? Can manufacturers determine breakdown SPL rating spec for headphones?

 

[JIW]

So it most likely will break before reaching 134 dB? Can manufacturers determine breakdown SPL rating spec for headphones?

If you mean SPL at rated maximum power that is easily calculated if sensitivity in dB SPL at 1V and impedance or SPL at 1 mW are known.

Power at 1 V equals 1 V divided by impedance in Ohms. For the HD800S that is 1/300 W or 10/3 mW. SPL for a given power is SPL at 1 V + 10*log10(Power/(Power at 1 V)). For the HD800S assuming SPL at 1 V is 105 dB, SPL at maximum rated power is 105 + 10*log10(500/(10/3)) = 105 + 10*log10(1500/10) = 105 + 10*log10(150) = 105 + 21.76 = 126.76 dB SPL. Alternatively, SPL at 1 mW + 10*log10(Power in mW).

Thus, the HPA4 with its 21.21 dBV maximum output at 300 Ohm has enough power for the HD800S to be only 0.55 dB below its SPL at maximum rated power.

 

[John_Siau]

Did the AHB-2 trip its limiter when attempting to drive the headphones prior to reaching its rating of ~28V RMS? An intelligent protection system (such as what is built into the Benchmark) in a power amplifier will not only detect excess current, but also high voltage swing with low current such as a 65R load would present.

In other words, it was limiting drive so as to not swing a high voltage, unloaded (65R is no load in real terms) output.

The output voltage limitation was due to the HE adapter. The adapter is a voltage divider. It attenuates the signal. The Topping was tested without the adapter, but the AHB2 was tested with the adapter. The AHB2 actually puts out quite a bit more voltage, but the HE adapter was attenuating the signal to a level that was lower than the output of the Topping.

We do not recommend using the HE adapter. The adapter attenuates the signal and it may add significant distortion. The AHB2 does not need to see a speaker load and it is perfectly happy driving the Susvaras directly.

Furthermore, the AHB2 has no limiter in series with the output. If you trip the protection in the AHB2, it mutes and stays muted until you restart the amplifier. In other words, if it had tripped, you would know it. You would also see plenty of blinking lights before it tripped.

The AHB2 protection system is not in the signal path. Therefore it cannot corrupt the signal in any way. It is a monitoring circuit that will shut down the amplifier before any damage can occur.

The protection system is monitoring current, voltage, temperature, transistor safe operating area (SOA), short circuit conditions, and amplifier induced distortion. If you come close to the shutdown thresholds, or exceed the thresholds for predetermined safe time periods, indicator lights will flash.

 

[John_Siau]

yep, HPA4 = 131dB (balanced) and 126dB in SE mode.

Thanks for catching this error! The page has now been corrected to reflect Sennheiser's published specification (102.0 at 1 Vrms). This removes the HD 800 S from our list of headphones that could be driven somewhat "safely" by the AHB2. The AHB2 could easily let the smoke out of the HD 800 S. We all know they don't sound very good without the smoke.

Benchmark NL4-XLR4 Headphone Adapter Cable for AHB2 Power Amplifier

NL4 to XLR4 Headphone adapter cable for use with power amplifiers. This cable provides a connection from the NL4 SpeakOn outputs on an audio power amplifier to the XLR4 input of a balanced headphone cable. This should only be used with low-sensitivity headphones that require large drive voltages.

benchmarkmedia.com

 

[solderdude]

So it most likely will break before reaching 134 dB? Can manufacturers determine breakdown SPL rating spec for headphones?

Most do not specify it. I know Sennheiser tests at levels where the driver does not fry at prolonged continuous exposure.
As music is not continuous and highly dynamic it can usually withstand much higher peak power in music so 4x the nominal power rating usually is not a real problem for a minute or so. It is no fun listening at 130dB peak SPL though that would mean 110dB average or so which is extremely loud.

 

[JIW]

The output voltage limitation was due to the HE adapter. The adapter is a voltage divider. It attenuates the signal. The Topping was tested without the adapter, but the AHB2 was tested with the adapter. The AHB2 actually puts out quite a bit more voltage, but the HE adapter was attenuating the signal to a level that was lower than the output of the Topping.

As pointed out by solderdude in post #979, the adapter uses one 10 Ohm resistor in parallel and one 25 Ohm resistor in series with the headphone. Since the voltage across parallel resistors is identical, the voltage output of the amplifier is divided between the headphone and the 25 Ohm resistor. The Susvara's impedance being 65 Ohm, the voltage across the Susvara is reduced by the factor 65/(65+25) = 13/18 = 0.722.... The impedance of the adapter with the Susvara connected is 1/(1/10 + 1/(25+65)) = 1/(1/10 + 1/90) = 1/((90+10)/900) = 900/100 = 9 Ohm. Thus, the AHB can put 28.28 V RMS across the adapter. Peak to peak this is 80 V. The HE-adapter reduces this to 57.77 V which is still 1.43 dB above the A90's 49 V peak to peak. These calculations are in line with those of solderdude in post #979.

At 28.28 V RMS output, the voltage across the 25 Ohm resistor is 5/18*28.28 = 7.86 V RMS and thus the power absorbed by the 25 Ohm resistor is 7.86^2/25 = 2.47 W. At 113 dB, the voltage across the Susvara is only 11.5 V for which the AHB2's output is 15.9 V and thus the power absorbed by the 25 Ohm resistor is 0.78 W ((10^((113 - (94 + 20*log10(1/1.29)))/20)*90/65*25/90)^2/25).

Amir said in post #9 that the SPL hardly increased although he increased the input voltage. Further, he wrote in the review that he could increase the SPL with the A90 even go 1 dB beyond 114 dB but that would lead to severe distortion: "Narrow spikes usually indicate resonances so they are audible beyond their distortion characteristics and point to design issues. We can also see how fast they escalate. 94 to 104 dBSPL causes a 3 3X or so increase but go to 114 dBSPL and they shoot through the roof. What's more, if you go just 1 dB beyond, the drivers bottom out and just buzz! Wanting to rule out Topping A90's own distortion I switched to Benchmark AHB2. Alas, I was not able to get above 113 dBSPL as AHB2 ran out of voltage drive."

Thus, the difference in voltage across the Susvara between what the AHB2 with the HE-adapter should have been able to do and the A90 is around 3.5 dB at least.

Since Amir tested it at 104 dB after where it seemed to work, either the 25 Ohm resistor significantly increases its resistance as it heats up such that at say 20 V output of the AHB2 it already is at (1-11.5/20)*65 = 27.625 Ohm and at 24 V it is at 33.85 Ohm while at 28.28 V it is at 38.57 Ohm or something else is not behaving as it should.

Someone should test the HE-adapter at voltages from 15 V RMS to 30 V RMS, and check if its attenuation increases.

 

[solderdude]

Thanks for catching this error! The page has now been corrected to reflect Sennheiser's published specification (102.0 at 1 Vrms). This removes the HD 800 S from our list of headphones that could be driven somewhat "safely" by the AHB2. The AHB2 could easily let the smoke out of the HD 800 S. We all know they don't sound very good without the smoke.

Benchmark NL4-XLR4 Headphone Adapter Cable for AHB2 Power Amplifier

NL4 to XLR4 Headphone adapter cable for use with power amplifiers. This cable provides a connection from the NL4 SpeakOn outputs on an audio power amplifier to the XLR4 input of a balanced headphone cable. This should only be used with low-sensitivity headphones that require large drive voltages.

benchmarkmedia.com

It was JIW who noticed it and saw an oopsy from me as well.

Some HP's that might apply to the list:
AKG K1000 (86dBV, 155ohm)
MyST Izo-OS (89dBV, 28ohm)
AKG K120 (90dBV, 600ohm)
Beyerdynamic DT660 mk2 (93dBV, 600ohm)
HE-5LE (95dBV, 40ohm)

 

[JIW]

It was JIW who noticed it and saw an oopsy from me as well.

You had post #1000 and used it like that... How could I let that stand

 

[bodhi]

I don't get the reason behind 90% of what being discussed very very rigorously here, a very expensive headphone turned out to be technically mediocre compared to its cheapo sibling and the all hell breaks loose. But hey the plus side is that ASR got a lot of traffic and I get to enjoin popcorn.

Let's say you have dreamed of this wonderful headphone for a long time, read all the raving reviews many times over and finally pulled the trigger and got them with two year payment plan. When you have them at your home you spend a couple of hours just sitting in front of them, admiring how they look like on different stands. You have already chosen the ONE amp that will do justice to this masterpiece and when you finally plug it in and play your favorite song you are going to hear something magnificent, regardless of what the headphones actually sound like.

In the following months you share dozens of pictures of the headphones in different settings, with various cables, all which reveal the magic in different ways, in hobbyist forums. You got together in threads with other serious audiophiles (1st class) who have climbed the mountain and achieved the Susvara experience. You really feel you have arrived at the peak audiophile. It did hurt but it was worth it in the end.

...now, some dude measures the thing and concludes without much drama that "it looks and feels nice but kind sucks as a headphone, next one please".

If you are a human being, I think it would be very, very hard to just shrug this off with "oh boy, I really got bamboozled there, damn those loveable Hifiman rascals."

As for myself, I demoed these just couple of months back without much expectations on way or another. Only could be bothered for a few minutes with them because: nothing terrible, didn't hurt my ears, just plain old "not interested to hear these ever again" feeling. If I hadn't promised myself to stop buying more headphones for no reason I could buy a pair for something like 500€ just for the design and as a conversation piece.

 

[migo77]

I was curious how it will compare to Susvara with my own ears so ordered one.

 

[BHazard]

Honest, data driven reviews like this are why I great appreciate this site and Amir's contributions. Thanks for this!!

I did just pick up the Ananda Nano and like it a lot once I auto-eq'ed the highs a bit.

 

[Mr. Haelscheir]

I haven't perused this thread yet, but I would like to share here my measurements of the HE1000se and how it compares to the Arya Stealth and an EQed Meze Elite, whereby the HE1000se is indeed an incremental improvement over the Arya Stealth and probably much more refined of a transducer than the underdamped Susvara, though not as impressive for distortion as the EQed Meze Elite: https://www.head-fi.org/threads/hifiman-he1000-se.886228/page-320#post-17865003 (post #4,788). I am glad I had lost my original interest in the Susvara from months ago on FR jaggedness and CSD dirtiness grounds.

 

[ALaylowguy]

Let's say you have dreamed of this wonderful headphone for a long time, read all the raving reviews many times over and finally pulled the trigger and got them with two year payment plan. When you have them at your home you spend a couple of hours just sitting in front of them, admiring how they look like on different stands. You have already chosen the ONE amp that will do justice to this masterpiece and when you finally plug it in and play your favorite song you are going to hear something magnificent, regardless of what the headphones actually sound like.

In the following months you share dozens of pictures of the headphones in different settings, with various cables, all which reveal the magic in different ways, in hobbyist forums. You got together in threads with other serious audiophiles (1st class) who have climbed the mountain and achieved the Susvara experience. You really feel you have arrived at the peak audiophile. It did hurt but it was worth it in the end.

...now, some dude measures the thing and concludes without much drama that "it looks and feels nice but kind sucks as a headphone, next one please".

If you are a human being, I think it would be very, very hard to just shrug this off with "oh boy, I really got bamboozled there, damn those loveable Hifiman rascals."

As for myself, I demoed these just couple of months back without much expectations on way or another. Only could be bothered for a few minutes with them because: nothing terrible, didn't hurt my ears, just plain old "not interested to hear these ever again" feeling. If I hadn't promised myself to stop buying more headphones for no reason I could buy a pair for something like 500€ just for the design and as a conversation piece.

buying headphones on plan is not really a good idea

 

[migo77]

How can I volume match Zero7 IEMs to Susvara? I'm outputting 210mV 1kHz sine test signal from amp to Susvara, it is around 82dB, what voltage I need to set to get the same SPL for 7Hz Salnotes Zero? Thank you.

 

[WhoSaidThat]

How can I volume match Zero7 IEMs to Susvara? I'm outputting 210mV 1kHz sine test signal from amp to Susvara, it is around 82dB, what voltage I need to set to get the same SPL for 7Hz Salnotes Zero? Thank you.

MS Copilot says:

"To volume match two headphones, you need to know their sensitivity ratings, which indicate how loud they can get with a given input voltage. According to the web search results, the 7Hz Salnotes Zero IEMs have a sensitivity of 108 dB/V1 and the Hifiman Susvara headphones have a sensitivity of 83 dB/V2.

Using the formula SPL = sensitivity + 20 * log10(V), where SPL is the sound pressure level in dB, sensitivity is the sensitivity rating in dB/V, and V is the input voltage in V, we can calculate the voltage needed to get the same SPL for the 7Hz Salnotes Zero IEMs as the Hifiman Susvara headphones.

If the Hifiman Susvara headphones produce 82 dB SPL with 210 mV input, then the 7Hz Salnotes Zero IEMs would need an input voltage of:

V = 10^((SPL - sensitivity) / 20)

V = 10^((82 - 108) / 20)

V = 0.0063 V or 6.3 mV

Therefore, you need to set the output voltage of your amp to 6.3 mV to get the same SPL for the 7Hz Salnotes Zero IEMs as the Hifiman Susvara headphones."

 

[Mr. Haelscheir]

I personally think in-ear microphones would allow a most accurate volume-match between two headphones insofar as you can choose an appropriate part of the frequency response to normalize around, but I suppose that isn't an option when comparing with IEMs.

 

[Blorg]

Therefore, you need to set the output voltage of your amp to 6.3 mV to get the same SPL for the 7Hz Salnotes Zero IEMs as the Hifiman Susvara headphones."

Manufacturer sensitivity ratings are nowhere near accurate enough to do it this way. Not even close, you could be an order of magnitude off. You won't get an accurate volume match like this, worse if you try it and convince yourself you do have one because you followed a process.

In-ear microphones sounds like a good idea.

Even playing pink noise through two outputs with one connected to the Susvara and the other the IEM, and swap L/R on and compare with one in each ear (i.e. listening to both at once) while tweaking the level of both outputs. This is not going to get you 100% accurate but it would be more reliable than relying on manufacturer sensitivities as they are usually just wrong.

Either way it's impossible for this to be a blind test, and personally, I don't feel I can really compare over-ears and IEMs directly like that, they have different presentations. If I was trying for a subjective impression though I think I'd try to volume match subjectively with one in each ear to start.

 

[HD800Fan]

I am of the opinion that the original HD800 is the best EQ'ed headphone ever made.
Looks like I won't have to change my opinion.

 

[John_Siau]

Some HP's that might apply to the list:
AKG K1000 (86dBV, 155ohm)
MyST Izo-OS (89dBV, 28ohm)
AKG K120 (90dBV, 600ohm)
Beyerdynamic DT660 mk2 (93dBV, 600ohm)
HE-5LE (95dBV, 40ohm)

Is the "AKG K120" the correct model number? When looking it up, I found this: "AKG introduced its first headphone, the K120 DYN, in 1949." Did AKG reuse the old model number, or is it typed incorrectly in your post?

 

[Rhamnetin]

Is the "AKG K120" the correct model number? When looking it up, I found this: "AKG introduced its first headphone, the K120 DYN, in 1949." Did AKG reuse the old model number, or is it typed incorrectly in your post?

It wouldn't be the only classic in that list!