Headphone amp recommendations (HE-560 and HD6XX)

[maxxevv]

Plenty amps can reach 5V, phones, tablets and small low power amps won't. These are not designed to drive high imp. cans.

Wonder what's your opinion/experience with regards to audiophile specific phones such as the LG V20 / V30 / V35 / G6 /G7 on driving high impedance headphones such the HD650 / 6XX in this case ?

 

[solderdude]

Yep, anything that can deliver around 5V in 300 Ohm will drive the HD6x0 just fine.
Most people probably won't drive their HD6x0 above 1V.

I have written some words about the HD650 and how much power/voltage it needs to play at certain levels.
It can be found HERE

 

[solderdude]

Wonder what's your opinion/experience with regards to audiophile specific phones such as the LG V20 / V30 / V35 / G6 /G7 on driving high impedance headphones such the HD650 / 6XX in this case ?

I have no idea how much output voltage they have.
Can't find it in any spec sheet but some folks may have measured it.

As most phones have about 3.7V battery voltage and there probably aren't any internal DC-DC converters in there to boost the voltage rail most likely the output voltage will be around 3.5Vpp = 1.2Vrms and 1.7Vpeak
This could be double the voltage if the phone has balanced output (dunno if any of them have this)
As most people don't drive their HD650's above 1V these phones might be able to drive them to decent levels where one man's decent is another man's too loud and another's way too soft.

 

[maxxevv]

Yep, anything that can deliver around 5V in 300 Ohm will drive the HD6x0 just fine.
Most people probably won't drive their HD6x0 above 1V.

I have written some words about the HD650 and how much power/voltage it needs to play at certain levels.
It can be found HERE

Thanks Franz,

I have read that a long while back, great information. In my own experience, and of course its my opinion, these phones can drive the Hd650/6XX to well over "comfortable" listening threshold levels. But whether they actually have enough juice to support the transient response requirements for the headphone to sound its best / most correct is another matter which I haven't had much reference to compare from/with.

Which is why I'm always bewildered when the crowd over at HF seems to be suggesting the Bottleneck Crack when many of them were just parroting comments ...

Is there even any truth in that at all to begin with ?

 

[solderdude]

Some people simply prefer the tonal balance change of the Crack's high output impedance and like to see tubes glow which gives them the impressions of warmth and comfort.
If that rocks their boat then I am all for it.
It's when they start telling everyone how much more accurate or 'natural' it sounds is when I start frowning.

And yes, indeed it's the transients that get clipped first. These short peaks can easily be seen in those scope shots.
A small amount of clipping won't be noticed by many.
It also depends on how dynamic (DR rating) the recording is.
Compressed to death DR5 recordings can play louder before clipping starts (to become obvious) than when high DR recordings are played back.

It's why I am always in favor of 10dB more headroom than one needs. Just to make sure nothing clips even when you play really loud.

 

[maxxevv]

Haha.. that's what drove me nuts too. There is a great deal of personal preferences interjected as facts in a lot of those comments regarding the Bottleneck Crack.

Anyway, I was experimenting with the opamp chips on my portable DAC Amp, noticed something which I'm not entirely sure if its my own imagination or really is a thing though. It was on AD797 chips before I swapped them out to LT1128 chips.

It lost some of the 'filled-up' sound of the AD797 and gained a bit of " width and depth" while listening to the HD6XX. Sort of like a 'airier' sounding headphone as a result. I tried it with my in-ears, but the effect were no where as obvious. It got me a little perplexed as to what was really happening, or was it purely my imagination.

Side note: On tracks known to have marginal sibilance issues, it was also more evident with the LT1128 chips compared to the AD797.

As for transient clipping, would where the transient peaks occupy make a difference to how such clipping can affect the sound of the headphone if the electrical demands of these peaks can't be met ? I can't recall exactly how the HD650 impedance curve is like but in theory, if the transient peak (of any headphone for that matter) occupies a swath of frequencies that are most frequently present in certain music tracks, and the amplifier powering it clips, wouldn't it alter the overall sound tonality of the headphones as a result ?

Pardon my long winded descriptions as I'm mechanically trained by profession, electrical and electronics need a little more elaborate lay description to get it off the ground for me.

 

[Wombat]

Headphone output is often taken from the output of a conventional amplifier via a set value series resistance. 220 ohm is common.

DIY: How to match your amp/phones: https://diyaudioheaven.wordpress.com/tutorials/power-amp-adapter/

 

[trl]

[...]
The T60RP is an orthodynamic planar headphone and is NOT damped electrically at all so damping factor is not an issue.
These headphones need quite a lot of voltage (and current) to be driven loudly.
92dB/mW @ 50 Ohm = 105dB/V and rated 3W.
That last spec says little. Music peaks of 3W is not the same as 3W continuous power.

The Burson can provide around 9V into 50 Ohm = 1.6W output R = 6 Ohm DF= 8.3 current draw = max 180mA
a 50W amp (assumed in 8 Ohm) = 20V = into 50 Ohm = 8W output R= 0.1 Ohm ? DF= 500
a 50W amp (assumed in 4 Ohm) = 14V = 4W output R= 0.1 Ohm ? DF=500

Damping Factor is a non issue, even at 8.3

[...]

So the FUN will no doubt drive it fine even with its poor DF (which is a non issue).
[...]

I've no idea how BURSON is measuring the output impedance, but I measured 0.39 Ohms for the FUN and about 0.45 Ohms for the PLAY (Amir found about the same output impedance for PLAY). I've used 1 KHz sines of few V RMS...between 25%-50% of amplifier's max. power.

For FUN I needed to find a resistor of less than 4 Ohms to use in parallel with outputs to lower FUN's output voltage from 100%@600Ohms to 90%@<4Ohms, so from 10V RMS to 9V RMS. I would call this a very good dumping factor.

I've also used BANG (2xLM3886TF inside) with FOSTEX T50-RP and Hifiman HE-560 and had no problems driving them both (low gain used as safety) and with a DAC with variable output volume in front of BANG.

I've got perfect compatibility for both FOSTEX T50-RP and Hifiman HE-560 with PLAY and FUN, but also with Matrix HPA-3B as well (4 output transistors/channel).
For moderate listening levels also ASUS Essence One (2xLME49860 @12V) can do the job, same I can say about the Objective2 with a gain of 3-3.5X (careful with the "exploding" NJM4556 output buffers when driving planars!).
For insane people that really want to have lot of power reserve (like >5W/channel @40-50Ohms) I've tested the above cans with Pioneer A-209R and Burson BANG and sound was very good. However, BANG had no background noise, instead A-209R had some noise under quiet environment (Direct drive used, a bit of noise was still there).

Per Tyll's measurements to one of his HE-560 seems that we need about 2.5mW to get to 90dB. Digizoid does this better than me, so based on Tyll's impedance and sensitivity measured I was able to get this:

Listening Loudness Voltage Needed Current Needed Power Needed
Safe 85 dB SPL 0.18 Vrms 4.19 mA 0.75 mW
Moderate 100 dB SPL 1.04 Vrms 24.19 mA 25.15 mW
Fairly Loud 110 dB SPL 3.29 Vrms 76.51 mA 251.72 mW
Very Loud 115 dB SPL 5.85 Vrms 136.05 mA 795.87 mW
Painful 120 dB SPL 10.4 Vrms 241.86 mA 2515.35 mW

So a decent 1W/channel amplifier should drive HE-560 well enough.

AFAIK a headamp needs to be able to drive the cans to about 110-115dB when 0dB signals are used. For highly compressed music that probably means >95dB of average SPL, but for normally recorded music (at the same knob volume position) there should no be more than 85-90dB of average SPL. So the 115dB is just the max. SPL the cans are handled by the amplifier, those peaks for a very short amount of time and not the average SPL our ears get exposed to.

However, for our safety, worth a read: https://www.innerfidelity.com/conte...-guide-articles-headphones-and-hearing-safety.

 

[solderdude]

I used the data supplied by the manufacturer.
Perhaps the 6 Ohm in the spec sheet should have said .6 Ohm ?

 

[mindbomb]

I noticed John Siau dwells here (who has my greatest admiration) and has measured increased distortion when the output R is higher which appears to be the 'biggest' proof at the moment.
What my 'counter' theory here is ... voltage division again.
You have 0 Ohm source resistance and measure at the output of the device. All voltages there are solely coming from the amp. The headphone's generator is shorted so the induced current by the voicecoil won't become visible at all.
Add a 10 Ohm resistance INSIDE that amplifier box/device and things become different.
On the output the actual signal will appear (of course) but signals generated by the voicecoil that run through the voicecoil + output R thus will create a voltage across both the voicecoil and output R.
Since the output signal of an amp is measured as a black box with a 10 Ohm output R both the applied signal (from the amp) + the divided current (from the voicecoil + output R) will be present at the output of the amp measured.
As a distortion measurement is nothing more than measuring the difference between the input signal from the amp and the output signal minus the gain then it is logical one 'measures' a bigger difference when the output signal + attenuated back EMF from the driver is compared to the input signal.
This doesn't make the distortion that much higher, it only appears that way.

Those tests have also been done here, and in the chord hugo 2 thread, the 10 ohms of the topping dx7 was found to cause higher distortion on even 300 ohm headphones and planar magnetic headphones, albeit less than with other headphones (it's somewhat hard to find since it's buried in the thread). I am still unclear on what's going on here. Isn't the extra current from the voicecoil evidence of not enough damping? So why wouldn't the distortion actually be higher?

 

[trl]

I used the data supplied by the manufacturer.
Perhaps the 6 Ohm in the spec sheet should have said .6 Ohm ?

I have no idea, maybe they're measuring this across the entire audio spectrum and around 20 KHz the impedance is indeed higher.

 

[solderdude]

Those tests have also been done here, and in the chord hugo 2 thread, the 10 ohms of the topping dx7 was found to cause higher distortion on even 300 ohm headphones and planar magnetic headphones, albeit less than with other headphones (it's somewhat hard to find since it's buried in the thread). I am still unclear on what's going on here. Isn't the extra current from the voicecoil evidence of not enough damping? So why wouldn't the distortion actually be higher?

Yes, the 'extra current' from the driver is evidence of not enough damping. It will overshoot or not react fast (accurate) enough.
But the actual current that runs in that circuit is generated by the driver which has an internal resistance (the DC resistance of the driver) which mainly determines which current will flow as that impedance is usually much higher than the one in series with it. Namely R out of the amp.
As Rout is much smaller than R driver the damping current (which does the electrical damping) does not differ much... a few percent lower on a higher output R. With low impedance headphones the effect of the Rout becomes bigger of course.

The measured extra distortion is simply the 'back EMF' current coming from the driver which differs from the applied voltage.
All mechanical and dynamic transducers work the other way around as well (thus as a mic/generator).
That current, determined by the motion strength (total mechanical damping) and generated current by the driver + output R, drops (divided by R-out and R-driver) across the output resistor (R-out). The Rout inside the amp/black box, and thus is measured as a 'difference' from the applied signal = measured distortion.
The lower the output R of the amp is the less back EMF voltage is measured as the resistance where one measured across is smaller and the source impedance remains the same (voltage division). So the lower the measured 'difference' to the input voltage is the less THD is measured.

That's my explanation for measuring higher distortion.
I could very well be wrong about this but would like to see another explanation in that case.

 

[Nango]

I'm always fascinated about discussions of "hard to drive" headphones. Headphones only require, at worst, a few tens of mW to drive them to daft volume levels. This isn't difficult to acheive in any way to very low (amp) distortion levels.

However what is required is an appropriate output voltage from the amp to suit the impedance of the cans. Generally higher impedance will need higher voltage.low output zshould always be sought.

For one given reason manufacturers like Sennheiser and beyer choose 45Ω and 120Ω respectively for their own amps ....... and not 0Ω which
is not really difficult to achieve.

Also, cans from Sennheiser tend to vary its impedance from 300Ω to 600Ω and above; its impedance has nothing to do with what they print on
their specs. Even the PortaPro doubles its impedance from 60Ω to 120Ω and then back to 60Ω. These swings always occure in the frequency
range around 100Hz where is supposed to reside the "body" of the music. A good amp has always to manage well all these impedance swings.

Also, impedance figures between dynamics and planars can not be compared, they work totally different so they are hardly comparable.

 

[March Audio]

For one given reason manufacturers like Sennheiser and beyer choose 45Ω and 120Ω respectively for their own amps ....... and not 0Ω which
is not really difficult to achieve.

Also, cans from Sennheiser tend to vary its impedance from 300Ω to 600Ω and above; its impedance has nothing to do with what they print on
their specs. Even the PortaPro doubles its impedance from 60Ω to 120Ω and then back to 60Ω. These swings always occure in the frequency
range around 100Hz where is supposed to reside the "body" of the music. A good amp has always to manage well all these impedance swings.

Also, impedance figures between dynamics and planars can not be compared, they work totally different so they are hardly comparable.

I certainly wouldn't buy any headphone amp with a 45 or 120 Ohm output impedance.

Yes an amp has to manage these impedance swings but we are still talking mW of power and mA of current. It's not a huge challenge like where we see some odd (read poor) speaker designs that dip to say 2ohms.

MP cans are primarily a resistive and constant impedance across the frequency range. Not difficult to drive contrary to the belief of some.

Dynamic can's vary impedance yes, but as I said you need an appropriate amp output voltage, low output impedance to suit that and their sensitivity, doesn't mean it's particularly difficult.

 

[Graph Feppar]

The new Fiio K3 looks good,it only cost 99€ and its successor of the popular E10 that NwAwGuy recommended back in the day.

It seems to have alot improvements, volume control is now digital so no channel matching and mechanical reliability problems, it have balanced output on top of single ended, probably cheapest balanced ampDac ever.

It have AKM 4452 and 1 ohm output impedance, low & high gain and enough voltage, current and power to drive about everything, frequency response is flat and extended, no rolled off treble or bass. It seems like alot performance for very little money, it might be the most logical choice if someone just want something perfectly transparent but doesnt want to spend any more than necessary.

 

[pwjazz]

Wonder what's your opinion/experience with regards to audiophile specific phones such as the LG V20 / V30 / V35 / G6 /G7 on driving high impedance headphones such the HD650 / 6XX in this case ?

I use an LG V20 with my 150 Ohm HD58X if I'm listening at low volumes like 70 dbA it does okay, but if I turn on my EQ with negative gain and want to listen at louder levels it doesn't quite cut it. @amirm did a test of the related LG G7 which includes power ratings at various impedances.

 

[trl]

For one given reason manufacturers like Sennheiser and beyer choose 45Ω and 120Ω respectively for their own amps ....... and not 0Ω which is not really difficult to achieve.[...]

Lot of manufacturers still can't lower the output impedance for TPA6120A or even BUF634/LME49600 buffers, so...seems to be complicated to add resistors and inductors in parallel after all (I've seen that in TwistedPear design).

What do you mean by "one given reason"? What would be this reason, please?

From what I can see Beyerdynamic A2 has an output impedance switchable between 0 Ω/100 Ω https://europe.beyerdynamic.com/amfile/file/download/file_id/841/product_id/3478/, so they seem to care about the low impedance output buffer after all.

However, the A20 has indeed a huge output impedance of 100 Ohms, you can actually see the 100 Ohms SMD resistors here https://www.av-online.hu/pictures/gallery/beyerdynamic-a-20_2014-06-16/Beyerdynamic_A20_inside_2.jpg, also stated in the datasheet here: https://europe.beyerdynamic.com/amfile/file/download/file_id/3135/product_id/3271/. I've no idea why they did that...I mean for 600 Ohms cans this should be fine, but driving 32 Ohms cans from an amplifier having a dumping factor lower than 1 seems insane to me.

Sennheiser HDVD800 and HDV820 have an output impedance of about 40 Ohms (based on various forums, Head-Fi and SBAF as well). Probably work very well with high impedance cans, but I wonder how the low damping factor will affect 16-32 Ohms cans.

 

[Nango]

I dont know what the reason could be, but they got to have one good reason for doing so, I guess. I also took from a pal of mine that impedances lower than 50 Ohm always tend to "struggle" every voltage regulator inside the amp (by eigenmodes), so it simply couldn't sound well. Therefore firms like Burson started building an option to regulators, they then came up with their own circuiteries, claiming these will not only be able to regulate the voltage but also to control and even doing lots of other tasks, being way better than the old-fashioned regulators. He added, law of physics can not be broken, those circuits were nonsens. I can imagine this is what happens when people say "a given phone is "picky" with matching with certain amps"...........

Anyway, I always prefer better plugging my HD 800 and even my PortaPro into 120 Ohm than into the 10 Ohm my amp also features. The only problem is then they are not loud enough, my amp outputs only 6V.

 

[trl]

@solderdude , Frans, would you mind comment "Must offer variable output impedance (the way many manufacturers make their amplifiers sound a bit different) So 3 settings were included" http://garage1217.com/garage1217_diy_tube_headphone_amplifiers_015.htm, please? I believe your answer should cover the above couple of post as well.

Many thanks,
Raul.

 

[trl]

I found an interesting thread on SBAF: https://www.superbestaudiofriends.o...ier-output-impedance-calculator-for-rew.7008/.

What intrigues me is that bass seems to not be affected when using 20 Ohms IEMs and different output impedance amplifiers. Last time I've tested my 16 Ohms IEMs on a LME49600 output buffer with a 10 Ohms series resistor the subbass was very low; when replacing 10 Ohms resistor with a 5 Ohms one the subbass got very present. When A/B-ing between a zero-Ohms headamp and this LME49600 5-Ohms amp I got no audible differences.

I wonder why in the SBAF graph the lowest octave seems unchanged with different output impedances.

P.S.: I think @amirm might need to use the AP with a Polaris headamp and see what happens when switching between the 3 output resistors; ideally would be to use some resistors on the outputs, if not real cans. Thank you!