Become a Site Supporter and Never see Ads again!

Author Topic: Portable headphone amps. Chord Mojo.  (Read 2022 times)

0 Members and 1 Guest are viewing this topic.

Offline Gutbucket

  • record > listen > revise technique
  • (15)
  • Needs to get out more...
  • *****
  • Posts: 14300
  • Gender: Male
  • Gunther Theile nailed it!
Re: Portable headphone amps. Chord Mojo.
« Reply #15 on: January 15, 2021, 11:56:15 AM »
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.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Numpy

  • + pace, amore e felicita +
  • (0)
  • Needs to get out more...
  • *****
  • Posts: 14011
  • Gender: Male
    • Oceana North America
Re: Portable headphone amps. Chord Mojo.
« Reply #16 on: January 15, 2021, 04:22:12 PM »
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      >:D




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

"Peace is for everyone"
        - Norah Jones

"Music is the drug that won't kill you"
         - Fran Lebowitz

Offline ts

  • (69)
  • Needs to get out more...
  • *****
  • Posts: 3373
  • Gender: Male
Re: Portable headphone amps. Chord Mojo.
« Reply #17 on: January 16, 2021, 06:35:56 PM »
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.  ;D
« Last Edit: January 16, 2021, 08:38:21 PM by ts »
Beyerdynamic CK930>Sound Devices MixPre 6

Offline voltronic

  • (34)
  • Needs to get out more...
  • *****
  • Posts: 3397
Re: Portable headphone amps. Chord Mojo.
« Reply #18 on: January 24, 2021, 11:32:32 AM »
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.
DPA 4061 ~ Line Audio CM3 ~ Naiant X-Q ~ AT 853  |  Naiant PFAs ~ Shure FP24  |  Zoom F6 ~ Sony PCM-M10
MOTU M2 ~ KRK Rokit RP5 ~ Sennheiser HD 650 ~ Etymotic ER4XR

Team Line Audio

Offline Gutbucket

  • record > listen > revise technique
  • (15)
  • Needs to get out more...
  • *****
  • Posts: 14300
  • Gender: Male
  • Gunther Theile nailed it!
Re: Portable headphone amps. Chord Mojo.
« Reply #19 on: January 27, 2021, 03:49:34 PM »
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.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Numpy

  • + pace, amore e felicita +
  • (0)
  • Needs to get out more...
  • *****
  • Posts: 14011
  • Gender: Male
    • Oceana North America
Re: Portable headphone amps. Chord Mojo.
« Reply #20 on: January 29, 2021, 10:19:52 PM »
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

"Peace is for everyone"
        - Norah Jones

"Music is the drug that won't kill you"
         - Fran Lebowitz

Offline OldNeumanntapr

  • (1)
  • Taperssection All-Star
  • ****
  • Posts: 1037
  • Gender: Male
Re: Portable headphone amps. Chord Mojo.
« Reply #21 on: March 24, 2021, 09:50:57 PM »
I have the FIIO and it's been pretty good, and was only $139. I think it's the e12?

Offline Gutbucket

  • record > listen > revise technique
  • (15)
  • Needs to get out more...
  • *****
  • Posts: 14300
  • Gender: Male
  • Gunther Theile nailed it!
Re: Portable headphone amps. Chord Mojo.
« Reply #22 on: March 25, 2021, 09:24:12 AM »
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!
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

 

RSS | Mobile
Page created in 0.041 seconds with 33 queries.
© 2002-2021 Taperssection.com
Powered by SMF