Topic: Portable headphone amps with Senn Hd 6xx

[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!