Topic: Portable headphone amps with Senn Hd 6xx

[ts]

Finally after about two years of trying different headphone amps/dacs for my beloved Sennheiser HD 650’s, I’ve settled on two. The FIIO Mont Blanc and the OPPO HA-2. The OPPO has a built in DAC and the FIiO is just an amp. While the FIiO can crank the cans to amazing levels, I like the sound of the OPPO better with my phone. Make sense as the DAC in the phone is inferior to that of the OPPO. The OPPO does do a great job with my closed backs though.

There is one other Amp/dac that I’ve yet to try. It’s pricey and I hate the form factor but I’m tempted as the reviews with the HD650’s are all good. The Chord Mojo. Anyone here have one I can demo? Of course I’ll cover shipping back and forth.

Thanks.

[Gutbucket]

I've been curious about the MiniDSP headphone amp, primarily due to the built-in DSP filtering possibilities which provide simple EQ for correcting by ear, in addition to the deeper capabilities of applying correction curves tailored to the specific headphone, a user's personal HRTF or both in combination.  Have you considered or come across any information about it?

https://www.minidsp.com/products/dsp-headphone-amp/ha-dsp

I also use Senns (HD600/650/700)

[ts]

I've been curious about the MiniDSP headphone amp, primarily due to the built-in DSP filtering possibilities which provide simple EQ for correcting by ear, in addition to the deeper capabilities of applying correction curves tailored to the specific headphone, a user's personal HRTF or both in combination.  Have you considered or come across any information about it?

https://www.minidsp.com/products/dsp-headphone-amp/ha-dsp

I also use Senns (HD600/650/700)

I can’t tell if it’s fully functional without the app. I’m an iPhone guy. It looks like all the custom tailored functions are in the android app? I would love the bass and treble control.

I have original 580’s, Drop 58x Jubilees and original 650’s. I like to get them thumping when no ones around. 

[Gutbucket]

Looks to me that one form or another of their control app works with iOS, as it is mentioned in the manual. [edit- no, will play from iOS but requires Mac for filter setup, see below] Would need to dig deeper in their forum or elsewhere to confirm.

But yeah, unfortunate that there are simple bass and treble knobs on the thing that can be easily adjusted without connection to an external device running an app.  It appears that tone/filtering control without connection to the app is limited to switching between four saved presets stored in the unit.  Those could be setup as simple preset bass/treble settings (and/or more complex filtering setups), so there is some degree of adjustment without connection to the app, if not as much as would be ideal for dialing in the tonal adjustments often needed for various taper recordings.   It would be more like choosing between four settings chosen so as to be applicable in general.

[Gutbucket]

Reading more deeply.. The primary filter setup and preset saving program is available for both Mac and Windows OS'.  The unit is able to connect to an iOS device as playback source, but the app needed to adjust filtering via a mobile device is Android only.  As a work around you could setup the presets to provide a limited degree of tonal modification on the go when playing material from an iOS source.

Bummer that it does not feature a way to access the bass/treble filtering directly on the unit as that would greatly increase functionality.  If that were the case I'd immediately buy one for use with my recorders, as well as other sources.  In that way complex corrective DSP filtering for specific headphones and/or listeners could be setup and saved to the four presets, and any necessary overall tonal adjustment needed for the material being listened to could be adjusted to  taste as desired while listening.  Wouldn't really need the app unless you also wanted parametric EQ adjustability on the go.

[ts]

Thanks for digging deep! Looks like they have a no return policy. Unless one of their US dealers will stock it and accept returns, I’ll probably have to pass. Appreciate all your research.

[Gutbucket]

Thanks for the motivation to dig a bit.  Let us know which way you end up going.

[ts]

I really want to demo a Mojo, (for me to demo I have to buy and hope theres a good return policy if I don’t like it) but I’m concerned about this statement I found on Amazon, when asked if the Mojo can properly drive the 650’s:

“The Mojo puts out 70mW into a 300ohm load and the 6xx series really like closer to 200-300 mW.”

That’s a pretty big difference.

[jerryfreak]

full review including headphone measurements

https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-chord-mojo-dac-and-amp.5120/

[ts]

Thanks for that. I tried to make the best of what I could out of the charts, however it was his test results with the 650’s and his conclusion that meant the most to me.

[jerryfreak]

from what i gather from the headphone tests, with the low impedance output it should be able to drive the 650s accurately up to the pint of clipping (the output not the phones), but it will begin to clip at a relatively low current output. the way the distortion curve rises so steeply this should be audible. so it will work but not at high volumes? seems there are lots of headphone amps in that price range that would be a better fit for 650s

[ts]

Finding the right portable for the 650’s is probably hopeless. They need desktops with tubes I guess. The Mojo would have been the last portable for me to try and it’s looking doubtful.

My desktop is a Drop 02 and the Drop Grace DAC. It’s works pretty good on the 650’s but not as good as I would like. Whatever playback software I happen to use I still have to EQ the bass way up. In my old office I used a Grace M902>650’s and depending on the tunes it was hit or miss. If I ever find myself with an extra $900, it’s going to be a Bottlehead Crack with the speedball upgrade. 

[ts]

I really want to demo a Mojo, (for me to demo I have to buy and hope theres a good return policy if I don’t like it) but I’m concerned about this statement I found on Amazon, when asked if the Mojo can properly drive the 650’s:

“The Mojo puts out 70mW into a 300ohm load and the 6xx series really like closer to 200-300 mW.”

That’s a pretty big difference.

Usually don’t make a habit of quoting myself, but I think I’m getting closer to understanding the power requirements for the 650’s.

Based on the above statement I should be looking for say 250 mW into 300ohms. My FIIO E12 can do 880 mW into 32ohms, but I can’t find a rating for 300ohms on this amp. My OPPO HA-2 is rated at a mere 30mW into 300ohms. No wonder I can turn the volume all the way up and still not feel the potential of the 650’s.

There must be a formula to convert. As in if the FIIO is doing 880 at 32, what’s it doing at 300ohms? Not all amps are listing mW ratings at 300 ohms. If I can convert what they do list maybe I’ll have a better shot at finding the right portable for these power hungry cans.

Thanks!

[Gutbucket]

My audio math is weak but I suspect the answer can be found or determined by the info in this blog post- https://nwavguy.blogspot.com/search?q=more+power+

..that link found in this discussion- https://www.audiosciencereview.com/forum/index.php?threads/headphone-amplifiers-and-high-impedance-headphones.18460/

[ts]

👍

[Gutbucket]

Sufficient Voltage output to accommodate dynamic peaks may be the challenge in getting the most from HD650 with a portable battery-powered amp.

Below is quoted from p.53 of the HD650 modifications PDF located here: http://www.mediafire.com/view/d9kb768up61eh3b/HD650_modifications.pdf
Sourced from the Headphone Articles section on this page: https://diyaudioheaven.wordpress.com/downloads/
It is often said the HD650 is 'difficult to drive', but is it ?
From a technical point of view the HD650 is NOT difficult to drive.
An efficiency of 98dB @ 1mW is neither low nor high. Because the nominal impedance is around 300  it
does require more voltage to reach that same milliWatt of power.
To reach 90dB peak (for about 80dB average levels) you only need 0.16mW (0,00016W) = 0,2V.
To reach 105dB peak (for about 95dB average levels), which is quite loud, you need 5mW = 1,3V.
You don't need much current to reach these levels either... just 4mA.
No amplifier has problems delivering 1.3V and 4mA, but not all amplifiers have a decent phase and FR.
This means you don't need a high POWER amplifier to drive the HD650 pretty loud.
Where does all the 'you need a high power amplifier' talk come from ?
Well suppose you are listening to a DR20 recording or a classical recording with softer passages and very
loud ones and you want that reproduced 'life-like' and free of distortion.
To reach those levels you need to reproduce 120dB peaks which seems like a LOT and painful but it isn't
really as those peaks are very short and will just sound 'dynamic'.
To reach that 0,16W = 7.1V = 22mA. The mA's is no problem not even for op-amps. To reach 7.1V you need a
power supply voltage of 24V.
This is something no 'phone' or 'ordinary' portable player can reach. You need a desktop amp for this.
So to be able to crank the headphone up to loud levels while maintaining the best possible sound quality you
need quite some 'headroom' in the amplifier = higher output voltage.
The distortion levels of most amplifiers will be magnitudes LOWER than what the headphones themselves
show at levels above 100dB SPL.
When the amplifier that is used to drive the HD650 must also be able to drive other, lower impedance
headphones such as HiFiman HE-6, which is around 40the amplifier must be able to deliver at least 1W.
This is where the 'you need a powerful amp' talk originates from.
The reality is you just need enough VOLTAGE when you want to drive the HD650 loud and nice.

[Chilly Brioschi]

Is anyone actually wearing HD-650s in need of a portable amp ?

 Drop just posted this for $220

https://drop.com/buy/smsl-sp200-thx-aaa-888-balanced-headphone-amp

Not a huge discount, but still an annoying temptation     




Features:
THX AAA-888 Technology
Ultra-Compact design - great for desktop
Toggle switch for operation, input selection, and gain control
Balanced stereo headphone output
Balanced stereo line input
High precision resistors for temperature stability
Pop-less design with high quality relays
Selected high precision low-distortion volume potentiometer
Full protection with DC, over-voltage, over-current, and short-circuit
Thermal protection on headphone amplifier
High-efficiency ultra-low noise power supply

Specs:
Inputs: Balanced x 1, Unbalanced x 1
Outputs: Balanced x 1, Unbalanced x 1
Output Power:
6W x 2 (16ohm)
3W x 2 (32ohm)
440mW x 2 (300ohm)
220mW x 2 (600ohm)
SNR: 130dB, A-Weighted
Output Noise: 2.8uV, A-Weighted
THD+N: -122dB, 0.00007% (1kHz, 32ohm)
THD+N: -117dB, 0.00013% (20 - 20kHz, 32ohm, -3dB)
THD: -125dB, 0.00006% (1kHz, 16ohm, -3dB)
Output Impedance: Near 0ohm
Frequency Response: 0.1Hz - 500kHz(-3dB)
Gain: Low(+6dB), High(+18dB)
Power Supply Voltage/Frequency: AC100-240V, 50-60 Hz
Power Consumption (EN60065): 24W
Power Consumption in Standby Mode: < 0.1W
Size: 160 x 149 x 73 mm
Weight: 772g

[ts]

That amp looks nice. I’m on Drop a lot and always check out the desktops. Problem is these days I’m not at my PC that much. All my work is done from my phone or iPad, hence the need for a good portable for my HD cans. I need a kick ass portable. 

[voltronic]

Sufficient Voltage output to accommodate dynamic peaks may be the challenge in getting the most from HD650 with a portable battery-powered amp.

Below is quoted from p.53 of the HD650 modifications PDF located here: http://www.mediafire.com/view/d9kb768up61eh3b/HD650_modifications.pdf
Sourced from the Headphone Articles section on this page: https://diyaudioheaven.wordpress.com/downloads/
It is often said the HD650 is 'difficult to drive', but is it ?
From a technical point of view the HD650 is NOT difficult to drive.
An efficiency of 98dB @ 1mW is neither low nor high. Because the nominal impedance is around 300  it
does require more voltage to reach that same milliWatt of power.
To reach 90dB peak (for about 80dB average levels) you only need 0.16mW (0,00016W) = 0,2V.
To reach 105dB peak (for about 95dB average levels), which is quite loud, you need 5mW = 1,3V.
You don't need much current to reach these levels either... just 4mA.
No amplifier has problems delivering 1.3V and 4mA, but not all amplifiers have a decent phase and FR.
This means you don't need a high POWER amplifier to drive the HD650 pretty loud.
Where does all the 'you need a high power amplifier' talk come from ?
Well suppose you are listening to a DR20 recording or a classical recording with softer passages and very
loud ones and you want that reproduced 'life-like' and free of distortion.
To reach those levels you need to reproduce 120dB peaks which seems like a LOT and painful but it isn't
really as those peaks are very short and will just sound 'dynamic'.
To reach that 0,16W = 7.1V = 22mA. The mA's is no problem not even for op-amps. To reach 7.1V you need a
power supply voltage of 24V.
This is something no 'phone' or 'ordinary' portable player can reach. You need a desktop amp for this.
So to be able to crank the headphone up to loud levels while maintaining the best possible sound quality you
need quite some 'headroom' in the amplifier = higher output voltage.
The distortion levels of most amplifiers will be magnitudes LOWER than what the headphones themselves
show at levels above 100dB SPL.
When the amplifier that is used to drive the HD650 must also be able to drive other, lower impedance
headphones such as HiFiman HE-6, which is around 40the amplifier must be able to deliver at least 1W.
This is where the 'you need a powerful amp' talk originates from.
The reality is you just need enough VOLTAGE when you want to drive the HD650 loud and nice.

Funny you mention this. My 650s sound just fine straight out of my Galaxy S10e phone, but won't get loud enough with portable recorders or external interfaces. That is, until I purchased my MOTU M2 which does drive them cleanly to levels plenty loud enough.

[Gutbucket]

Non-normalized taper recordings that retain excess headroom from when the recording was made will suffer this more than other material because they require more gain/voltage output to achieve the same output level through the phones.  Such is the case for many of of my classical recordings.

[Chilly Brioschi]

Non-normalized taper recordings that retain excess headroom from when the recording was made will suffer this more than other material because they require more gain/voltage output to achieve the same output level through the phones.  Such is the case for many of of my classical recordings.

Raising Power Against Fixed Impedance increases Voltage ?
as like:
V = P/I

[OldNeumanntapr]

I have the FIIO and it's been pretty good, and was only $139. I think it's the e12?

[Gutbucket]

Non-normalized taper recordings that retain excess headroom from when the recording was made will suffer this more than other material because they require more gain/voltage output to achieve the same output level through the phones.  Such is the case for many of of my classical recordings.

Raising Power Against Fixed Impedance increases Voltage ?
as like:
V = P/I

Code for social-sexual tension!