Help finding components for headphone amplifier

[firstcolle]

Hi,
I'm thinking about my next project and I would build an audiophile headphone amplifier.

those are the fixed spec:
- high audio quality
- analog in/analog out
- able to drive  8/16/32 Ohm headphone
- digital volume control (encoder + picmicro maybe IR or BT remote)

I'm looking for some IC amplifier that matches the high audio quality and maybe with i2c gain or a VCA. is there something in the market?
or I have to think about a pre amplifier with i2c gain control and then a second stage for the amp?
is there some project to take a look for start?


many thanks!

[Alex Nikitin]

- high audio quality
...
- digital volume control (encoder + picmicro maybe IR or BT remote)

IMHO, these two requirements are mutually exclusive  .

Cheers

Alex

[NiHaoMike]

TI makes some high quality audio PGAs like the PGA2311/PGA4311.

[Fungus]

What's the signal source?

[tszaboo]

PGA2310/11 volume control
TPA6120A2 output amplifier
OPA1612 or OPA1622 anyewhere else required

The issue is not the signal chain. The issue is reasonably powering it (like, not 230V input, and no noisy DC-DC converters), and having a high quality source (AKA: USB DAC)

[NiHaoMike]

If you can put in an internal DAC, you can use something like the PCM1792A which has a built in gain control.

[Fungus]

The issue is not the signal chain. The issue is reasonably powering it (like, not 230V input, and no noisy DC-DC converters), and having a high quality source (AKA: USB DAC)

That's why I asked what the source is.

If it's USB then you can get a complete headphone DAC for under $10 on eBay.

eg. http://www.ebay.com/itm/281827865856   (randomly chosen seller)

Chipset is this: http://www.ti.com/lit/ds/symlink/pcm2704.pdf

If you want 'audiophile' capacitors it's a couple of bucks extra. 

And if you don't trust the 2704's built-in amplifier you can have external op-amp.

[firstcolle]

hi all..

the source will be only RCA analog input with line levels, so I prefer to not convert the signal into digital, process it and then reconvert into analog.
potentially te audio source will be a turntable with a proper preamplifier.

i'm going to look at the component you suggested.. thanks!!!

[The Soulman]

For volume control you can look at voltage controlled amplifiers (VCA) such as from THATcorp.
They are used in the most expensive Pro-audio equipment.
Toshiba used to make nice digitally controlled volume control IC (TC94xx) but seem to be obsolete.
Why do you need a digitally controlled volume control and not a motorized potentiometer?

The actual power-amp shouldn't be difficult to make, at these low power requirements a single ended class-A
topology is very doable.
Or copy a design from a high dollar commercial product.
Or look at the c-moy op-amp based designs.

[aries1470]

Hi,
besides the T.I. parts, Maxim (Dallas) has a great range, either push-button or i2c controlled.

Here is a link to their product portfolio. Just go to the Logarithmic

[f5r5e5d]

http://www.njr.com/MUSES/series/MUSES72320.html

[Alex Nikitin]

hi all..

the source will be only RCA analog input with line levels, so I prefer to not convert the signal into digital, process it and then reconvert into analog.
potentially te audio source will be a turntable with a proper preamplifier.

i'm going to look at the component you suggested.. thanks!!!

Even a simple dual carbon track pot will be much better for the sound than any of these digital controls. If you need the remote capabilities and prefer not to sacrifice the sound quality you can use either a motorised pot or a relay controlled attenuator (6 relays will give you 0 to -64dB attenuation in 1dB steps).

Cheers

Alex

[Marco]

http://www.njr.com/MUSES/series/MUSES72320.html

LM1972 is a bit less esoteric.

[f5r5e5d]

Hi,
I'm thinking about my next project and I would build an audiophile headphone amplifier.

[BrianHG]

http://www.njr.com/MUSES/series/MUSES72320.html

LM1972 is a bit less esoteric.

The LM1972 has no gain, just -0db (full volume) and down to -78db with only 4.5v to 12v supply, which it only needs in this case since it wont amplify the audio level.

MUSES does +31.5db to -111.5db.

If power supply current is not a factor, and you want an excellent digital volume, class A headphone amp with a bit of kick, I would use the MUSES, powered at full 30v (+/-15v), have the output drive 2 x 30v ultra logic level (1.2-1.8v) mosfet gate directly operating in voltage follower mode, with a big 5 watt pull down resistor to -15v (only adjusted for a 1.5-2watt draw).  With AC decoupling caps to drive the headphones/speakers.  Controlled by the MCU of your choice.

This makes a minimal 1 chip for gain and volume, digitally controlled, 2 opamps, or dual opamp & 2 mosfets (TO-220 packages with heatsink to radiate the 3-4 watts) for the most basic class A output, or, 2 NPN darlingtons for a tighter sound,  again class A, for a nice minimal analog design.  (No feedback on the output driving transistors.)

Clean output with 0 crossover distortion, but, expensive & you need a hefty +/- 15v supply.

There are nice cheaper solutions if you want to use a motorized mechanical volume control.

[BrianHG]

You can always buy this guy:

https://www.aliexpress.com/item/50-KA-Remote-Motor-Volume-Potentiometer-Control-Adjustable/2053612708.html?spm=2114.10010108.1000013.4.rPwWC0&traffic_analysisId=recommend_2088_2_82199_new&scm=1007.13339.82199.0&pvid=03f30272-400a-48fb-bd81-6f145cea8bf3&tpp=1

And build a high quality headphone amp with a fixed 10db gain connected to it to drive your output.

Or, a complete passive multi-channel pre-amp with this guy:

https://www.aliexpress.com/item/Electronic-volume-control-board-With-mini-remote-control-Brand-new-remote-control-ALPS-motor-potentiometer-Pre/32645946961.html?spm=2114.10010108.1000014.6.rjlDjP&traffic_analysisId=recommend_3035_null_null_null&scm=1007.13338.84300.000000000000000&pvid=fd043381-de34-49db-bfb8-dcb4335592ce&tpp=1

[Marco]

If power supply current is not a factor, and you want an excellent digital volume, class A headphone amp with a bit of kick, I would use the MUSES, powered at full 30v (+/-15v), have the output drive 2 x 30v ultra logic level (1.2-1.8v) mosfet gate directly operating in voltage follower mode

All that engineering spend on linearity, thrown away. Not that it matters.

[BrianHG]

If power supply current is not a factor, and you want an excellent digital volume, class A headphone amp with a bit of kick, I would use the MUSES, powered at full 30v (+/-15v), have the output drive 2 x 30v ultra logic level (1.2-1.8v) mosfet gate directly operating in voltage follower mode

All that engineering spend on linearity, thrown away. Not that it matters.

Linearity with Darlington BJTs wouldn't be too terrible, but, I like high current drives without feedback when driving cable and low power dynamic loads like headphones.  But, that's just my ears...

[f5r5e5d]

unless you need more V theres no point in descrete outputs for dynamic headphones

the right op amps, particularly the CFA DSL drivers are faster in global feedback than many output Q followers you see in headphone project amps

the TPA6120 is also happy pushing 100s of ma to within a volt or so of the rails

wrap one in a good 'audio' fet input op amp's global feedback loop and passives, pcb layout are bigger distortion sources

[tszaboo]

The issue is not the signal chain. The issue is reasonably powering it (like, not 230V input, and no noisy DC-DC converters), and having a high quality source (AKA: USB DAC)

That's why I asked what the source is.

If it's USB then you can get a complete headphone DAC for under $10 on eBay.

eg. http://www.ebay.com/itm/281827865856   (randomly chosen seller)

Chipset is this: http://www.ti.com/lit/ds/symlink/pcm2704.pdf

If you want 'audiophile' capacitors it's a couple of bucks extra. 

And if you don't trust the 2704's built-in amplifier you can have external op-amp.

None of these things qualify as audiophile. It is 192KHz 24 bit.
And before we start a war: 24 bit is the next logical step for 16, might be an overkill. 192Khz makes reconstruction filter easier to make.
TPA6120 can drive anything, except the planar headphones. Unless you want attery power, I dont see the reason to use anything else.

Or look at the c-moy op-amp based designs.

Cmoy is best, when one battery dies, and your amplifier is suddenly the headphone killer.

http://nwavguy.blogspot.be/2011/07/cmoy-with-gain.html
Read this guy's blog. He is the EE with audio passion. I wonder where did he disappear.

[Fungus]

None of these things qualify as audiophile. It is 192KHz 24 bit.

Oh, we have a definition of that term now! Nothing less will do. Got it. 

[Fungus]

- high audio quality
...
- digital volume control (encoder + picmicro maybe IR or BT remote)

IMHO, these two requirements are mutually exclusive  .

You can get a motorized potentiometer, control the motor with the PIC. 

If this is a 'project' for listening to vinyl then I'd build something with valves as a bit more of a challenge.

Where's the fun in using one of the hundreds of single-chip-solutions?

[BrianHG]

- high audio quality
...
- digital volume control (encoder + picmicro maybe IR or BT remote)

IMHO, these two requirements are mutually exclusive  .

You can get a motorized potentiometer, control the motor with the PIC. 

If this is a 'project' for listening to vinyl then I'd build something with valves as a bit more of a challenge.

Where's the fun in using one of the hundreds of single-chip-solutions?

See the links I placed in post #15...

[Alex Nikitin]

- high audio quality
...
- digital volume control (encoder + picmicro maybe IR or BT remote)

IMHO, these two requirements are mutually exclusive  .

You can get a motorized potentiometer, control the motor with the PIC. 

If this is a 'project' for listening to vinyl then I'd build something with valves as a bit more of a challenge.

Where's the fun in using one of the hundreds of single-chip-solutions?

See the links I placed in post #15...

These links are most likely a waste of money if you aim at a half-decent sound quality. I did my first production remotely controlled volume with a motorised pot over 20 years ago, and the rule is  - never have anything digital running in the same enclosure as the pot, and if it is that close to the pot as in the links you've posted you can forget about a quality sound. Only if the micro is in the sleep mode (no clock) most of the time except when it needs to receive the remote signal and operate the pot, you can place it close. Then you have a problem of a sleeping micro that has to react to an incoming remote signal... . I very much doubt these Chinese boards do anything of that kind.

Cheers

Alex

[Pitrsek]

+ for TPA6120