Want to build a headphone amp.

[Fungus]

It's understandable that 'volt nuts' are better tolerated in EEVBLOG forums - test gear is the subject matter!

I've spent quite a few hours listening to and comparing audio equipment. I've always been of the opinion that most of the audible difference is in the speakers. Once you've spent about $200-$250 on an amplifier then you're pretty much done as far as electronics goes.

(nb. This is for home audio. Two speakers, average sized room)

Sources? It's all digital these days so it doesn't make any difference.

Speakers? You have to spend quite a lot to reach a plateau. Maybe $1500.

And ... the best thing you can do to improve most audio setups is to move the speakers around to find the best position/height relative to the listener and add some acoustic conditioning to the room.

[retrolefty]

It's understandable that 'volt nuts' are better tolerated in EEVBLOG forums - test gear is the subject matter!

I've spent quite a few hours listening to and comparing audio equipment. I've always been of the opinion that most of the audible difference is in the speakers. Once you've spent about $200-$250 on an amplifier then you're pretty much done as far as electronics goes.

(nb. This is for home audio. Two speakers, average sized room)

Sources? It's all digital these days so it doesn't make any difference.

Speakers? You have to spend quite a lot to reach a plateau. Maybe $1500.

And ... the best thing you can do to improve most audio setups is to move the speakers around to find the best position/height relative to the listener and add some acoustic conditioning to the room.

 You sir, sound like a 'true' audiophile.   

[suicidaleggroll]

It's understandable that 'volt nuts' are better tolerated in EEVBLOG forums - test gear is the subject matter!

I've spent quite a few hours listening to and comparing audio equipment. I've always been of the opinion that most of the audible difference is in the speakers. Once you've spent about $200-$250 on an amplifier then you're pretty much done as far as electronics goes.

(nb. This is for home audio. Two speakers, average sized room)

Sources? It's all digital these days so it doesn't make any difference.

Speakers? You have to spend quite a lot to reach a plateau. Maybe $1500.

And ... the best thing you can do to improve most audio setups is to move the speakers around to find the best position/height relative to the listener and add some acoustic conditioning to the room.

I don't disagree with anything you've said here, and in fact your comments mirror my own equipment to a large degree.  All digital sources, I don't care what they are, one nice DAC, about $300 in amps, and about $2000 on a pair of good towers.  No room treatment (no way the wife would go for that), but I do have a self-tuning digital RTA/EQ in the mix that does a LOT to reduce resonances at the listening position.

My only confusion is why you're fine spending $200-250 on an amp for speakers, but are under the impression that no amp is required for headphones?  For little $2 ear buds sure, but a lot of high end headphones are just as hard to power as a small set of bookshelf speakers.  There's no way the crappy little chip amp in a phone can do them justice.  It can get them to make noise, sure, but that's a long way off from performing correctly.

[Richard Crowley]

It's understandable that 'volt nuts' are better tolerated in EEVBLOG forums - test gear is the subject matter!

That wasn't obvious to me upon viewing the title.  It is more obvious by spending some time here seeing the videos and forum topics.

most of the audible difference is in the speakers.

And, for those of us who produce audio and video, in the MICROPHONES.

And generally is it axiomatic that physical to electrical (and vice-versa) TRANSDUCERS have orders of magnitude more impact on the sound than ANY electronics (except, of course, for electronics that is DESIGNED to distort the signal like e-guitar "fuzz boxes" et.al.)

Speakers? You have to spend quite a lot to reach a plateau. Maybe $1500.

And, curiously enough, much the same with microphones (if not more so).

And ... the best thing you can do to improve most audio setups is to move the speakers around to find the best position/height relative to the listener and add some acoustic conditioning to the room.

And, again, exactly the same with microphones.  At least those of us who record "classical" and "natural/ambient" kinds of things. Orchestras, bands, choirs, etc.  Selection of which microphone to use in which situation often involves spending hours in the venue during rehearsals to discover just the right spot to put the microphones. Since they don't "hear" like our ear/brain systems do, it is much more critical to get the mic in just the right position to capture the ideal ratio of direct/ambient sound to simulate what our ear/brain systems do for us automatically.

And, also in the cine/video world. Our eye/brain systems accommodate a much wider range of exposure and color temperature than ANY film/camera can hope to do.  It takes hours/days to "light" a scene or a venue to produce decent pictures that the audience will accept as "natural".

Of course modern, "pop" multi-mic, multi-track recording where the musicians may not even be performing "together" (in the same space and/or at the same time) and the song is effectively created in post-production editing is a completely different matter.

[Richard Crowley]

No room treatment (no way the wife would go for that), but I do have a self-tuning digital RTA/EQ in the mix that does a LOT to reduce resonances at the listening position.

Of course, that is a compromise you chose to live with. EQ (even automated by RTA) is only ONE dimension of a 3 or 4 dimensional proper listening space.  There are most likely ways of doing acoustic room treatment that your wife would accept. Especially if labeled as "redecoration". 

My only confusion is why you're fine spending $200-250 on an amp for speakers, but are under the impression that no amp is required for headphones?  For little $2 ear buds sure, but a lot of high end headphones are just as hard to power as a small set of bookshelf speakers.  There's no way the crappy little chip amp in a phone can do them justice.  It can get them to make noise, sure, but that's a long way off from performing correctly.

While true, it is equally true that you don't need a $200 or more amp to drive even "elite" headphones.  There is a fuzzy crossover point where true pursuit of high-fidelity reproduction becomes a completely subjective fetish.  Certainly a more socially acceptable fetish than many others.

[retrolefty]

While true, it is equally true that you don't need a $200 or more amp to drive even "elite" headphones.

 I agree with the possible exception of electrostatic headphones? I seem to recall they have rather exotic driving requirements, high voltages? Never listened to any of those types but maybe someone here has and knows if they required a specific amp driver type?

[Fungus]

No room treatment (no way the wife would go for that)

Yes, that can be a problem. Speakers are usually unhappy against walls and miserable in corners. They really need to be out in the open and quite close to the listener to sound good.

Hint for the non-singles: Mine are on little stands so I can just pick them up and move them to the sweet spot when I need them.

My only confusion is why you're fine spending $200-250 on an amp for speakers, but are under the impression that no amp is required for headphones?  For little $2 ear buds sure, but a lot of high end headphones are just as hard to power as a small set of bookshelf speakers.  There's no way the crappy little chip amp in a phone can do them justice.  It can get them to make noise, sure, but that's a long way off from performing correctly.

Some sort of amp is required, obviously.

My $300 headphones are supposed to be medium-difficult to drive but the $8 PCM2704 device I linked earlier works just fine. I actually bought another DAC with PCM2704+extra amplifier to compare. There really isn't any difference in sound though (not for me+my headphones anyway, YMMV).

Telephones are another story. I've never tried using headphones with one but I know from experience that iPhone outputs are weak (apparently it's because Apple is afraid of lawsuits from teenagers who went deaf because they listened to their music too loud).

So... I'll believe you might need an amplifier for headphones connected to a telephone. 

I don't see why it would be an expensive/exotic amplifier though, eg. TI have a whole selection of headphone amps for under $1 (and I'm sure other manufacturers do too).

I'm fairly sure you don't need to build something like this to drive your headphones, no matter how exotic they are:

[langwadt]

It's understandable that 'volt nuts' are better tolerated in EEVBLOG forums - test gear is the subject matter!

I've spent quite a few hours listening to and comparing audio equipment. I've always been of the opinion that most of the audible difference is in the speakers. Once you've spent about $200-$250 on an amplifier then you're pretty much done as far as electronics goes.

(nb. This is for home audio. Two speakers, average sized room)

Sources? It's all digital these days so it doesn't make any difference.

Speakers? You have to spend quite a lot to reach a plateau. Maybe $1500.

And ... the best thing you can do to improve most audio setups is to move the speakers around to find the best position/height relative to the listener and add some acoustic conditioning to the room.

speakers can easily have 10s of percent distortion and all kind of other artifacts so they are the weak link. 

amplifiers with unmeasurable noise and distortion and a bandwidth way beyond audio is easy

[Fungus]

I agree with the possible exception of electrostatic headphones? I seem to recall they have rather exotic driving requirements, high voltages? Never listened to any of those types but maybe someone here has and knows if they required a specific amp driver type?

You don't connect electrostatics directly to an ordinary headphone socket, they come with their own custom amplifier.

A lot of them use wall warts for power so I assume you could build a battery pack if you really want to.

Unless it's the amp shown below... 

[retrolefty]

It's understandable that 'volt nuts' are better tolerated in EEVBLOG forums - test gear is the subject matter!

I've spent quite a few hours listening to and comparing audio equipment. I've always been of the opinion that most of the audible difference is in the speakers. Once you've spent about $200-$250 on an amplifier then you're pretty much done as far as electronics goes.

(nb. This is for home audio. Two speakers, average sized room)

Sources? It's all digital these days so it doesn't make any difference.

Speakers? You have to spend quite a lot to reach a plateau. Maybe $1500.

And ... the best thing you can do to improve most audio setups is to move the speakers around to find the best position/height relative to the listener and add some acoustic conditioning to the room.

speakers can easily have 10s of percent distortion and all kind of other artifacts so they are the weak link.

But it's possible that human hearing and mental processing might even be a weaker link?

amplifiers with unmeasurable noise and distortion and a bandwidth way beyond audio is easy

 

[Richard Crowley]

I agree with the possible exception of electrostatic headphones? I seem to recall they have rather exotic driving requirements, high voltages? Never listened to any of those types but maybe someone here has and knows if they required a specific amp driver type?

You reminded me that I have a pair of Koss ESP-9 electrostatic headphones.  I am going to go and dig them up and refurbish them.

They certainly are much different than your typical "dynamic" (coil of wire and magnet) transducers. They take a high voltage (but very low current) signal. They probably take LESS actual power than dynamic headphones, but much different voltage/current levels. That doesn't mean that it takes thousand-dollar amps to drive it. Simply proper low-distortion, high-voltage drivers.  Pretty easy to do with modern semiconductors.

The original product came with a largish (~150mm cube) interface box which was mainly a pair of step-up transformers passively driven from the high-power speaker output of your stereo amplifier.  I believe they rectified part of the high-voltage signal into the "exciting" voltage required for the transducers (IIRC?)

[Richard Crowley]

speakers can easily have 10s of percent distortion and all kind of other artifacts so they are the weak link. 

And microphones, as well.  And furthermore, there are many "vintage" microphones with notably UN-flat frequency response. But people have come to like that "sound" and contemporary reproductions of some of those "classics" retain the anomalies despite modern technology that allows much more accurate performance.

amplifiers with unmeasurable noise and distortion and a bandwidth way beyond audio is easy

And mic input preamps, as well.  But there are still people who scavenge old tube junk specifically for the "colored" sound of the transformers.

And as for D/A converters, it is quite amusing to read which chips are found in both cheap consumer mass-market products AND in premium audiophle and professional products.  There is an epic thread over on Gearslutz: "Audio interfaces and their AD/DA chips LISTED"
https://www.gearslutz.com/board/geekslutz-forum/542009-audio-interfaces-their-ad-da-chips-listed.html

[Fungus]

speakers can easily have 10s of percent distortion and all kind of other artifacts so they are the weak link. 

amplifiers with unmeasurable noise and distortion and a bandwidth way beyond audio is easy

Interesting that everybody is agreeing with this, it's almost the opposite of what HiFi magazines recommend.

(usually you "spend at least as much on the amplifier as the speakers")

[tooki]

I've always been of the opinion that most of the audible difference is in the speakers. Once you've spent about $200-$250 on an amplifier then you're pretty much done as far as electronics goes.

(nb. This is for home audio. Two speakers, average sized room)

Sources? It's all digital these days so it doesn't make any difference.

Speakers? You have to spend quite a lot to reach a plateau. Maybe $1500.

And ... the best thing you can do to improve most audio setups is to move the speakers around to find the best position/height relative to the listener and add some acoustic conditioning to the room.

^^ This.    So much truth. I've been saying the same thing for years.

[Alex Nikitin]

A bit off-topic however I feel I have to say that:

To design a good sounding electronics is not a trivial task. There is much more to it than appears to an electronics engineer who has little to no experience in that very special area. Just as a simple example - yes, transducers are in theory the most non-linear parts of the audio chain. However for that very reason the electronics facing those devices on both ends is difficult to design right. Even a "perfect" amplifier has to work not with a dummy resistive load but with a very non-perfect speaker. So the real importance is how these two devices work together (and that is not an easy thing to get right, believe me, I've designed a number of amplifiers, including some very good ones, and some not so good).  It is like in any specialised area of electronics, as soon as you start to dig deep you have to change your perspective and to learn some nuances. And there is usually a good scientific ground to that knowledge, just many things that accepted as of no or little influence in "generic" electronics suddenly become important. In a similar way you pay attention to tellurium copper terminals and plugs, and to your lab temperature down to 0.1 degree precision if you are a volt nut  .

Cheers

Alex

[retrolefty]

speakers can easily have 10s of percent distortion and all kind of other artifacts so they are the weak link. 

amplifiers with unmeasurable noise and distortion and a bandwidth way beyond audio is easy

Interesting that everybody is agreeing with this, it's almost the opposite of what HiFi magazines recommend.

(usually you "spend at least as much on the amplifier as the speakers")

 The 'old rule' as i recall is to spend 50% of budget on speakers the other 50% on everything else not just amp.
As far as magazines recommendations go recall that they are dependent on ad income so must promote (or at least not discourage) spending.

[Fungus]

A bit off-topic however I feel I have to say that:

To design a good sounding electronics is not a trivial task. There is much more to it than appears to an electronics engineer who has little to no experience in that very special area. Just as a simple example - yes, transducers are in theory the most non-linear parts of the audio chain. However for that very reason the electronics facing those devices on both ends is difficult to design right. Even a "perfect" amplifier has to work not with a dummy resistive load but with a very non-perfect speaker. So the real importance is how these two devices work together (and that is not an easy thing to get right, believe me, I've designed a number of amplifiers, including some very good ones, and some not so good).  It is like in any specialised area of electronics, as soon as you start to dig deep you have to change your perspective and to learn some nuances.

As an amplifier designer, how much should a good audio amplifier with, say, 70-100W of power cost on the street?

A quick google search for "class ab 100w audio amplifier IC" came up with this in the first few results.

Low noise ...  0.01% THD  ...   6 Euros in one-off quantity on Mouser.

I suspect the 'amplifier' problem has been studied, the design compromises have been made and it's now available in a monolithic packages from a dozen different manufacturers. 

[Richard Crowley]

Interesting that everybody is agreeing with this, it's almost the opposite of what HiFi magazines recommend.
(usually you "spend at least as much on the amplifier as the speakers")

That is because we are speaking in the present tense.
Things were significantly different back 50 years ago when "HiFi magazines" were making this recommendation.
That was back when people were still using vacuum tubes and "heavy iron" transformers and amplifier distortion figures were integer numbers.

[Lightages]

I certainly can see wanting to use a separate headphone amp as many devices have horrible output stages. That is probably getting much less common as good parts are getting to be more like jelly bean parts. Some headphones need a bit more voltage as they are higher impedance so this is where a good headphone amp can help.

The bigger concern is the analog output of many notebooks, laptops, and tablets. A USB DAC can get the analog outside of that really noisy environment and into a better isolated one where things can be cleaned up and a proper driving amp for the difficult headphones can be implemented.

[Lightages]

The 'old rule' as i recall is to spend 50% of budget on speakers the other 50% on everything else not just amp.
As far as magazines recommendations go recall that they are dependent on ad income so must promote (or at least not discourage) spending.

Yes, "OLD" rule. The new rule, spend as much as you can on speakers and fixing your room. Almost every amp and sound source made now far surpass the capabilities and fidelity of the sources and amps way back when. The same with headphones. Spend as much as you can on them. If you are spending more than $100 (or even arguably less) on a headphone amp then you have priorities that don't match reality. I find it really funny when some people go crazy over hyped headphones, toob amps, and then listen to 128kbps MP3.

[Alex Nikitin]

A bit off-topic however I feel I have to say that:

To design a good sounding electronics is not a trivial task. There is much more to it than appears to an electronics engineer who has little to no experience in that very special area. Just as a simple example - yes, transducers are in theory the most non-linear parts of the audio chain. However for that very reason the electronics facing those devices on both ends is difficult to design right. Even a "perfect" amplifier has to work not with a dummy resistive load but with a very non-perfect speaker. So the real importance is how these two devices work together (and that is not an easy thing to get right, believe me, I've designed a number of amplifiers, including some very good ones, and some not so good).  It is like in any specialised area of electronics, as soon as you start to dig deep you have to change your perspective and to learn some nuances.

As an amplifier designer, how much should a good audio amplifier with, say, 70-100W of power cost on the street?

A quick google search for "class ab 100w audio amplifier IC" came up with this in the first few results.

Low noise ...  0.01% THD  ...   6 Euros in one-off quantity on Mouser.

I suspect the 'amplifier' problem has been studied, the design compromises have been made and it's now available in a monolithic packages from a dozen different manufacturers. 

Well, somebody may be perfectly happy with that. I'm not, as simple as that. I generally avoid listening to digital sources of "CD quality" and below altogether, though I've designed several pretty good CD players.  On the other hand, high prices are not an indication of quality, my home system (speakers, stands, amplifier, turntable, cables and cassette decks) did cost me probably about £1500 in total (all second hand) and I haven't changed it much for last 7 years or so.

Cheers

Alex

[Marco]

On the other hand ears aren't even particularly linear.

[AF6LJ]

I agree with the possible exception of electrostatic headphones? I seem to recall they have rather exotic driving requirements, high voltages? Never listened to any of those types but maybe someone here has and knows if they required a specific amp driver type?

You don't connect electrostatics directly to an ordinary headphone socket, they come with their own custom amplifier.

A lot of them use wall warts for power so I assume you could build a battery pack if you really want to.

Unless it's the amp shown below... 

Oh But think of all the fun you would have building a power supply...
Lots of LIPO batteries, a transistor driven high voltage supply, DC for the heaters....
 

Ah Hell Screw it...
Build a vibrator supply....
 

[retrolefty]

On the other hand ears aren't even particularly linear.

 Nor are they identical human to human. It's a wonder any subjective description of sound systems is worth offering. Measurement and double blind testing is the only path to audio 'truth' I suspect.

[Fungus]

(usually you "spend at least as much on the amplifier as the speakers")

That is because we are speaking in the present tense.
Things were significantly different back 50 years ago when "HiFi magazines" were making this recommendation.

I remember them saying it 20 years ago (which was probably when I last read a HiFi magazine).

But let's see what the web says today: 

From: http://www.cnet.com/news/how-to-buy-a-hi-fi-system/

"For regular speakers I like the Wharfedale Diamond 10.1 ($349/pair), matched with a JoLida JD301RC integrated amplifier ($425), and a Schiit Audio Bifrost DAC ($349)" (Speakers: 31% of the budget)

"If you have a big room, and really want to party, go for bigger speakers, like the Zu Audio Omen Standard ($1,500/pair) with a Peachtree Audio integrated amp/DAC ($1,799)." (Speakers: 45% of the budget)