
Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap - chablent
https://spectrum.ieee.org/consumer-electronics/audiovideo/build-your-own-professionalgrade-audio-amp-on-the-sort-of-cheap
======
S_A_P
Audiophilia is a study in contradiction. The ask is a flat "uncolored"
accurate sound. The gear that sells for ridiculous prices is usually tube gear
with limited bandwidth and makes ~15 watts at 5-10% (admittedly usually even
order harmonic) thd. Hardly uncolored.

That said, and Ive mentioned this before on HN. My (now late) uncle had a
bunch of audiophile friends in Dallas. He hung around folks who had spent
upwards of 500,000 (yes you read that right) on audio gear. I can't forget the
time I rolled up to a modest middle class home, only to find out that inside
of this house was a pair of Focal Grand Utopias (selling retail for 250k at
the time, though he said he paid around 60k for the pair). He had 2 750 watt
tube amps, current era but the brand escapes me. For source material he had a
heavily modified Technics SP-10 with 2 tone arm/cartridge combinations and a
boutique tube phono preamp. This fed into a similarly heavily modified Dynaco
tube preamp from the 1960s. When he really wanted to get serious, though, he
had a studer 2" tape machine and a sizable collection of low generation master
tape copies. If I hadn't seen this with my own eyes I would say my uncle was
full of shit when he told me about it. You know what? it sounded freaking
amazing.Im sure it is 90% placebo, and 10% the fact that he was able to play
high bandwidth audio to concert levels with no stress or strain from the
amplifiers. Was it worth 6 figures of money? not to me. But I am glad I got to
hear it...

~~~
sjwright
The three critical paths for high end sound reproduction are: loudspeakers,
speaker placement, room acoustics. Of course all parts of sound reproduction
matter, but those three are the ones that affect real systems in practice.

Most other factors are rarely an issue and/or inferior parts have a much lower
magnitude of impact on sound quality. Sufficiently good source material
(256kbps AAC or better) is widely available. Most amplifiers are fine. Almost
all wire/cable is perfectly good. High quality DACs are more abundant than you
might think (e.g. the digital inputs of any half-decent AV receiver made in
the past decade).

Good speakers.

Good placement.

Good acoustics.

Those are the ones to focus on. They're the ones to spend money on. If you
wanted to add a fourth to that list, I'd add an honourable mention to in-room
calibration systems like Audyssey and DIRAC. Depending on the sorts of
imperfections in a given system the opportunity for improvements with DSP
might be substantial and dramatic, or marginal to the point of being
irrelevant. (For most systems it's somewhere in the middle.)

~~~
S_A_P
You’re absolutely right about that. I didn’t even mention how all of the
drywall was replaced strategically with acoustic wall board. The entirety of
the living room was gutted and refurbished to be the ultimate listening room,
complete with stadium seating. Another recollection I just had is that he had
a separate electric circuit run to the house(as in a second set of wires
coming off the utility pole) so he could properly condition the power feeding
his audio gear.

Every aspect of the room was built around the grand utopias and their
placement. If you’re not familiar with them check them out here.
[https://www.focal.com/en/home-audio/high-fidelity-
speakers/u...](https://www.focal.com/en/home-audio/high-fidelity-
speakers/utopia-iii-evo/floorstanding-speakers/grande-utopia-em-evo)

The subwoofer drivers are unique in that they use an electromagnet instead of
the usual strontium or neodymium permanent magnet.

I think what impressed me the most was that this guy was not annoying or in to
the hand wavy audiophile hocus pocus. Just super passionate about getting
everything done to get the absolute best sound even if the bang per buck was
low. He had a wall of vinyl and was happy to let me pick several selections to
play. From what I understand, this guy would open his home to anyone
interested in a listening session. If anyone is in the DFW area and you can
get plugged in to that community it seemed like a great group of folks.

~~~
egeozcan
> Another recollection I just had is that he had a separate electric circuit
> run to the house(as in a second set of wires coming off the utility pole) so
> he could properly condition the power feeding his audio gear

In my limited experience, "clean power" (I know nil about this so I'm just
repeating what I hear) was the most important difference people would "hear".
My uncle used to have a Hi-Fi shop and I helped him sometimes. People hearing
distortions in their existing setup used to make up for 90% of his customers.
In those cases the number one step was to make sure that the power that comes
to the system is clean. Being a certified electrician, he used to do his thing
and you would almost always hear the "aaah" from the customers the moment you
hit play. To me also the difference was generally night and day.

~~~
sjwright
And yet such impressions conflict with how power supply circuits work and how
THD measurement works. Wall power is incredibly noisy and there’s nothing much
an electrician can do to change that. If this noise had any meaningful effect
on the sound—it doesn’t—you would be able to measure it as a variance in THD.

(Now of course that might be less true for some poorly made vinyl/phono level
equipment but if you actually cared about audible distortions you wouldn't be
listening to the sound of a needle scratching its way across a fragile plastic
groove in the first place...)

~~~
egeozcan
Maybe then it was because of the isolation that the audio cables got being
away from all the chaos created by the random power cables. I don't know. Most
of the time, it was a huge improvement. The next step was to fix/remove
anything that caused distortions.

------
proee
Audio is a great way to get kids excited about electronics. When I was in the
6th grade, my father helped me build my own high power amplifier using an
LM3876 opamp. I remember clear as day the first time I powered up my amplifier
circuit and nothing happened. Hmmm... I brought my face closer to my circuit
board and suddenly "BANG!!!!" an electrolytic capacitor blew up right in my
face and scared the living daylights out of me. I unknowingly connected the
power supply capacitor backwards. I soldered in a new capacitor, and then
plugged it in again. Like magic, my home-brewed subwoofer was now cranking out
serious bass by an amplifier that "I" built. That moment was magical and
surreal - I still get goose bumps thinking about it!

------
rubatuga
If you just want the amp without building it, you can get a TPA3116 Class D
amplifier. It is only $21 USD from aliexpress (with free shipping of course!).
It accepts a supply voltage of up to 24V meaning that you can just dig around
for your old laptop power supply (19V). It comes with a nice and sleek
aluminum case, and has low enough noise floor that I can't detect it at all
unless my ear is right up against the speaker. Although slightly less power
output compared to the chip from the article, it gets loud enough to drown out
someone yelling. This amp from aliexpress has gold plated banana plug
terminals, RCA inputs, and a smooth volume potentiometer.

Link: [https://www.aliexpress.com/item/Breeze-Audio-BA100-Class-
D-P...](https://www.aliexpress.com/item/Breeze-Audio-BA100-Class-D-Power-
Amplifier-Audio-Amp-TAP3116-Mini-Digital-Amplifier-Hi-fi-
Audio/32888620869.html)

~~~
blattimwind
I guess in technical terms this article is about "making" an amplifier as
opposed to "building" an amplifier. "Making" as in "Maker", since the
electronics come as pre-made assemblies connected together and put in a case.

~~~
compiler-guy
"If you wish to make an apple pie from scratch, you must first create the
universe." \--Carl Sagan

~~~
blattimwind
"There are only two colors in the world: black and white." \--Ansel Adams

------
vichu
I don't know much when it comes to audio amp design, but this reminds me
greatly of the O2 headphone amp[0] - that anecdotally a few of my friends have
soldered for their personal use.

[0] [http://nwavguy.blogspot.com/2011/07/o2-headphone-
amp.html](http://nwavguy.blogspot.com/2011/07/o2-headphone-amp.html)

~~~
korethr
I thought of the same thing. Both are inexpensive, straightforward, no-BS
projects that leverage the advances made in electronics over the years to
deliver quality audio.

If I made one of these, I 'd be tempted to put an ODAC and O2 board in the
same chassis to have a complete amplifier.

~~~
syntaxing
Hearing the ODAC name is quite a throw back! I remember reading NwAvGuy's blog
when I first started getting into headphones. I always wondered what happened
to him.

~~~
sjwright
Given the way he suddenly went to radio silence, I just assumed he was hired
by Apple...

------
neya
After I started building my own audio gear, I am no longer impressed by what
you can buy in the consumer market, no longer how much "audiophile" these
systems claim to be. Usually, it's just a simple 2-way boombox sold for $xxx -
$xxxx. I started my project after being disappointed with the sound quality of
the Apple Homepod. So, I built my own version with inbuilt basic voice command
integration. And I couldn't be happier. Funny, that I just finished building
mine this week[1][2].

It's also based on Tubes, and the sound is very, very satisfying. Will be
happy to share a detailed guide, if anyone's interested.

[1] [https://www.instagram.com/p/Bpl71mUHLbm/?taken-
by=discovery....](https://www.instagram.com/p/Bpl71mUHLbm/?taken-
by=discovery.diary)

[2] [https://www.instagram.com/p/BplhIIqHNhl/?taken-
by=discovery....](https://www.instagram.com/p/BplhIIqHNhl/?taken-
by=discovery.diary)

~~~
jollyrogerbass
That looks awesome, post the guide please!

~~~
neya
Alright, will post it soon on my Medium1: [https://medium.com/build-
ideas](https://medium.com/build-ideas)

Thank you :)

------
scblock
Oh geez they could have left this statement out: "When I wrote my previous
article, class-D audio was fairly new, and audiophiles were still arguing
about whether class-D amps could sound as good as class-AB or class-A units.

Nobody is having those arguments anymore."

Those arguments are still front and center when it comes to amplifier design,
both on the manufacturer and consumer sides.

~~~
AceJohnny2
Tangentially, the placebo effect is everywhere. If it can affect tasting
(wine) and hearing (audiophile gear), I'm surprised not to have noticed its
affect in discussing photography.

Will "computational photography" (as touted in the latest iPhones) that alters
photos based on criterion of perceived quality end up bringing these kind of
inane discussions there too?

Edit: Never mind, I didn't factor in all the arguments about Photoshop
altering.

~~~
rectang
I made my living as a mastering engineer for two years...

To do good work in mixing and mastering, it's important to study the human
perceptual mechanism and its propensity for illusion, and it's also important
to understand masking effects and how to amplify certain components long
enough to tweak them before dialing them back to recede into the gestalt.

It's also important to understand that in sound reproduction the vast majority
of the distortion on the analog side comes from transducers (microphones and
speakers), not amplifiers. (I'm not even going to bother with the article,
because amplifiers aren't an important problem: buy something decently
engineered and overpowered, and you're basically all set. Then worry about
your speakers and your room, because they're the hard part.)

But it's likewise crucial to grok that the distortion introduced by digital
components is disproportionately disturbing because it is enharmonic. And that
practically speaking a lot of the damage that gets done in practice happens
because people don't handle gain staging right and often don't understand the
fundamental principle of preserving high resolution throughout production and
only exporting to lower resolution as a final step.

In summary, there are a whole lot of interesting conversations to have on the
subject of audio and how perception relates to production. But it's basically
impossible to find a community to discuss these subjects with. Either it will
be overrun by audiophiles and their pseudoscience, or well-meaning but
undereducated skeptics will dominate the discussion with plausible but
misguided debunking.

So every once in a while I throw up a piece like this into the middle of a
giant discussion, with about as much hope as tossing a message in a bottle
into the ocean.

~~~
beat
I feel your pain. I produce and mix records - at an amateur level, but enough
to get quite good at it. It makes me want to toss all this "objective",
"measurable" bullshit from the skeptics right out the window - the subjective
experience is all that matters. But it also makes me want to toss the
audiophile voodoo out the same window. "Accurate" reproduction? I just want to
show them how records are mixed.

My pet example is that I put high-pass filters (12db slope) at 250-300hz on
almost everything that isn't a drum or a bass instrument. I'm slaughtering the
bottom two octaves of guitars! And if you solo a guitar track, you can hear
it. But in the context of a _mix_ , all those bottom two octaves do is make
mud and confusion, distracting from the clarity that the kick and bass (guitar
|| synth) needs. And I need that clarity, because I'm not mixing for $500,000
audiophile systems. I'm mixing for car stereos, boom boxes, Alexas, cheap
earbuds, and worse.

So all that matters for me with audiophile systems - and I _love_ audiophile
systems - is that they sound good. That doesn't mean they sound accurate.

~~~
rectang
I agree that your high-pass filters are an application of masking principles.
It would be challenging, especially for an untrained person but even for
someone who is trained, to perceive enabling/disabling of those filters in the
context of the full mix. Instead we solo to isolate the track being adjusted
so the change _is_ easily audible -- i.e. no longer masked by the other tracks
-- and adjust the filtering anticipating the counter-intuitive but
artistically desirable effect when the filtered track is blended back into the
mix.

Despite that, your hostility to the skeptics illustrates that you and I still
aren't really on the same page (though I don't doubt you produce compelling
art, don't question your techniques, and agree 100% about ensuring that
aesthetic gestures survive the transition to imperfect end-user environments).

To me, "objective accuracy" is a worthy and desirable intermediate goal for
sound artists, a tool which can be leveraged for creative ends the same as a
baker understanding food chemistry or an animator understanding Newtonian
physics or a modern origami folder understanding programming. However, chasing
"objective accuracy" means understanding the wildly non-linear, even bizarre
human perceptual mechanism -- which is more of a pattern recognition machine
and definitely not a measurement device -- in addition to all the strangeness
of acoustics.

The problem with audiophiles is that their approach to "accuracy" is
unscientific and doomed from the start. The skeptics on the other hand, have
the right idea -- but those who have not done deep study often fail to
appreciate just how difficult the problem is and how far off their intuitions
are.

I've had some wonderful conversations with individuals whose perspectives are
similar to mine, but it still seems impossible to find a hospitable public
forum.

~~~
beat
When I say "objective", it definitely needs air quotes, because the well-
meaning skeptics love to toss it around for some decidedly non-objective
opinions. My pet example is quoting "THD" as if it were a useful figure. It's
not. The advantage of THD isn't that it is meaningful, but rather that it's
easy to measure. Run a 1khz sine wave into the front of the amp, tap a
resistive load on the back of the amp, measure the difference. Manufacturers
like it because it makes for a competitive-sounding spec. But it has
approximately zero to do with how an amplifier behaves in the face of complex
musical signals, driving complex speaker loads.

When it comes to recording, my "objective" reality is the sound I hear in the
room before it ever hits a microphone. But what comes out of the other end of
the microphone is already deeply subjective. The objective ability of hi-fi
systems to reproduce that subjective, colored microphone signal (plus whatever
processing is involved downstream) is about as objective as they get. But the
recording itself? Outside the world of purely electronic music, it's a
subjective experience.

I play acoustic guitar every day, listen to unamplified singers/musicians
(other than me) at least weekly, play electric guitar at least weekly, gig
regularly. These direct, objective experiences of the natural sounds of
instruments color my interpretation of both magical-thinking audiophiles and
pseudo-scientific skeptics. I know intimately what the natural sound is, I
know intimately what the recorded/reproduced sound is, and I know how the
entire recording process works, from miking to mixing to mastering. Laws and
sausages. The audiophiles and skeptics are both missing that perspective.

So, as a recording/mixing engineer, as a _producer_ , I'm looking not to
deliver audiophile accuracy, but rather to deliver the intended intellectual
and emotional experience of the music. What feeling is the artist trying to
convey? How do I manipulate the sonics to emphasize the musician's intent, as
expressed through the lyrics, the composition/arrangement, and the natural
tones of their instruments? That's the fun part, for me.

(As an aside, I'm currently working on a particular song of my own, destined
for my long-delayed solo album. I wrote the song based on a nightmare I had in
great distress. A few years back, I suffered an illness that left me nearly
unable to speak, much less sing, and my voice is permanently damaged (I have
surgery a few times a year on my vocal cords to keep speaking and not die of
suffocation). I recorded the song right after writing it, just a couple of
weeks before my first surgery, with a near-useless voice. "My broken voice
won't fill the air / I know that you don't really care / You may not need my
song but I need to sing it anyway". Fitting with the broken voice is the
melody repeated on a piano that hasn't been tuned in over 50 years and has
been flooded multiple times, so it's, um, colorful. To both the audiophile and
objective mindset, neither the voice nor the piano were worth recording at
all. But as an artist trying to communicate an emotional experience, they're
vital.)

------
mmaunder
Google audiophile headphones. Then go to sweetwater and search for studio
headphones.

If the price of source gear is a quarter of the price of gear attempting to
reproduce source, something is broken.

~~~
Tsiklon
I like to look on high end headphones as I would any other luxury item - I'm
willing to pay for nice materials of a higher quality or a better experience,
if the item is right.

That could perhaps explain some of the price - plus I think we're at the point
where many of the headphone companies have discovered that there is an ultra-
high end market for some of these products.

You can see this in the prices of many top brand flagship headphones - the
majority of the well regarded brands have been gradually putting out
exceedingly expensive flagships in the past 2-3 years.

10 years ago - then the Sennheiser HD650 was seen as a flagship at $400, now
look at the Sennheiser HD820 released earlier this year at $2200.

You aren't going to find too many people who will say that the sound
improvements between the two justify an $1800 increase in MSRP.

However if you reframe the perspective to that of a luxury good, given the
perception of headphones (regardless of use case) has changed somewhat in the
interim and are seen as a fashion accessory and there's a larger enthusiast
pool - you can see that manufacturers would be willing to push new boundaries
when it comes to price.

However I think it's only the lunatics, or the conspicuous consumers who are
ignorant to the law of diminishing returns when it comes to headphones and
audio in general.

~~~
beat
Some people understand the law of diminishing returns, but have the resources
to not care. If a $2000 pair of headphones is no more real financial pain for
you than a $200 pair, and they're better despite diminishing returns, then why
not get them?

~~~
Tsiklon
Very correct, that's a perfectly reasonable explanation, especially in terms
of the usual consumers of high end luxury goods.

------
beat
Modern class D amps are terrific, but it's annoying to see THD brought up as a
measure of audio quality. THD is terrible measurement - its value is not that
it's relevant (except to demonstrate things aren't actually broken), but
rather that it's easy to measure.

An amplifier's ability to reproduce a 1khz sine wave into a resistive load
tells us nothing about how it behaves in the face of 8-10 octaves of frequency
range and the real dynamic range and harmonic complexity of actual musical
content, when hooked up to the absurdly complex and nonmusical behavior of
real speakers. The 5% THD of single-ended tube amps that people who've never
heard one tell us proves how "inaccurate" they are is inaudible, but the
grimy, dull sound of cheap amps that have excellent THD specs is plain to
hear.

It's frustrating, in part because this stuff is, so far, mostly impossible to
measure. It's hard to get a sense of how an amplifier will sound from specs.

~~~
mark-r
I'll never forget my wakeup call on the differences of sound between
amplifiers. I had been listening to headphones on my Techniqs receiver, a well
regarded unit with a THD of 0.04%. For some reason I plugged the headphones
into my Nakamichi cassette recorder instead, and was blown away by how much
better they sounded. Until then I had thought that amplifiers were a solved
problem and the inaccuracies of transducers like headphones would mask the
tiny differences between them. I never expected to be wrong.

------
Matsta
The majority of all active speakers produced nowadays are Class-D, it's
nothing really new (and the fact they are super cheap).

No idea how this guy wrote this article and didn't come across DIY Audio (or
he just didn't mention it in the article). There is a tonne of information
here:
[https://www.diyaudio.com/forums/class-d/](https://www.diyaudio.com/forums/class-d/)

~~~
irrational
I have some questions. My son has been taking guitar lessons using a classic
guitar. Using the advice of his instructor we are getting him a begginer's
electric guitar for christmas. We also need to get him an amp.

Is the amp in this article the same kind of amp that you could plug an
electric guitar into? I know nothing about music or instruments, but I do know
about electronics so I was thinking it might be fun to build an amp with my
son.

I went to the diyaudio link you suggested, but I didn't immediately see
information like in the article (buy this, this, this and this to build the
amp). Can you point to where I could find a similar purchase list and assembly
instructions on diyaudio? Thanks!

~~~
smcameron
Short answer: No. Guitar amps are weird, not like hi-fi amps at all. In a hi-
fi amp, distortion is the enemy. In a guitar amp, distortion is sought after.
Driving the pre-amp section of a guitar amp into clipping is _extremely
common_ and _desirable_. Doing the same with a hi-fi amp is _not_. A hi-fi amp
will be typically connected to speakers with a woofer and a tweeter and maybe
a mid-range, trying to accurately reproduce all frequencies. A guitar amp
typically has nothing but 12 inch speakers. A guitar amp is literally _half
the instrument_. Plugging a guitar into a hi-fi amp is faithfully amplifying
1/2 of an instrument. You'll end up buying a guitar amp anyway. Just get a
guitar amp.

~~~
Steve44
> A guitar amp is literally half the instrument.

I'm not a musician and this confused me for some time. I'd see electric
guitars with their own amp & speakers then a microphone for the the PA system
in front of said speaker. I couldn't understand why the electric guitar wasn't
just plugged in, something I read a few years ago was a light-bulb moment.

------
kposehn
> Nobody is having those arguments anymore. There are many class-D amplifiers
> on the market now, and the best of these are dominating the upper reaches of
> the high end.

Not quite. Frankly, Class A or AB still has the upper hand from a pure sound
quality perspective, and class D struggles to output sufficiently at high
levels with lower levels of distortion in my experience.

That said, there have been many small class-D Amps from Lepai and Dayton that
are excellent choices for near-field and non-demanding applications. They
definitely have their place. The tech is advancing rapidly but it has not
supplanted A or AB.

If you want some background in why there is still debate, I highly suggest
reading some of Nelson Pass’ interviews and writings:

[https://www.google.com/amp/s/parttimeaudiophile.com/2018/02/...](https://www.google.com/amp/s/parttimeaudiophile.com/2018/02/21/an-
interview-with-hifi-legend-nelson-pass/amp/)
[https://www.passlabs.com/press/single-ended-
class](https://www.passlabs.com/press/single-ended-class)
[https://www.passlabs.com/press/leaving-
class](https://www.passlabs.com/press/leaving-class)

~~~
radus
This may be true of Class D amps commonly used in home equipment, but many
high end powered PA speakers use Class D amps and get very loud with minimal
distortion.

~~~
TylerE
You'd be surprised how much you can get away with in a PA.

Being powerful and reliable is more important than being all that good, since
the room always sounds bad anyway.

------
mrob
It's bizarre how none of these chips seem to have a digital input. All my
music is digital, and despite the modern rise of vinyl, I don't think that's
unusual. If I want an amplifier like this then I'm forced to have a completely
useless DAC/ADC pair degrading the signal quality. Does anybody know of an
easily available class-D amplifier with digital input? You'd think that would
be an obvious feature for a digital amplifier.

~~~
WalterBright
All stereo components, except the amp connection to the speaker, should be
ethernet. Turntable, CD player, cassette, pre-amp, everything.

Then make it wifi.

Just think, you could eliminate that awful rat's nest of cables. The sound
quality would be better. You could locate components where-ever convenient.
Each component could have a web browser interface.

It'd be awesome.

~~~
tsukikage
Digital, sure. Standardized even, sure. But wifi, going through who knows what
network stacks, routers, filtering, and sharing with other traffic? I'd like
some guarantees on latency, please; I like my video in sync with my audio.

~~~
WalterBright
It would be on your home LAN, so presumably you know what else is using it. I
stream video from my computer to a Roku box over ethernet, video consumes far
more bandwidth than audio, and it works fine.

Also, if you plug your audio components into its own switch, it should not get
interference from the rest of your LAN.

------
linsomniac
I kind of want to build one of these amps and connect it to a set of speaker
built with these cheap exciters... One of the Youtube channels I follow messed
around with them [https://youtu.be/zMCyF400l1c](https://youtu.be/zMCyF400l1c)
but he got that from this other video
[https://youtu.be/zdkyGDqU7xA](https://youtu.be/zdkyGDqU7xA) where he goes
into all sorts of experiments he ran on the exciters to find the right design.

------
jelling
Any recommendations for people that are tempted to build this but should
really put their time elsewhere?

~~~
01100011
Just do some research and get a cheap class D amp off a chinese website. I
forgot the one I chose(I'm at work now), but other than some sparks if you
jiggle the power connector(haha seriously. can be fixed with a tiny bit of
effort), it is an amazing little amp. It also supports optical and bluetooth
connections which is really nice.

I put my efforts into building speakers instead. I got a cheap kit
([https://www.diysoundgroup.com/overnight-
sensations.html](https://www.diysoundgroup.com/overnight-sensations.html)) and
spent my time learning how to apply a french polish finish. I really enjoyed
learning french polishing. It's one of those things that when you finally get
it, it becomes immensely satisfying. Yeah, shellac isn't the most durable
finish, but it sure is pretty.

~~~
muks
> Yeah, shellac isn't the most durable finish, but it sure is pretty.

+1

------
watersb
Very cool. I was very interested when the IEEE Spectrum original feature was
published, and got one of the Tripath amplifiers to play with. It was a
commercial product, marketed as inexpensive toy. Then people on Head-Fi Forums
started taking these things further. One of the forum members started modding
home-theater amplifiers, so I purchased one and it was great.

Vinnie Rossi, Red Wine Audio. It is still amazing. But his stuff is now quite
out of my price range.

These amplifiers are great fun, though.

------
lalorieri
[for guitars] Depends on what you consider professional. We've made a simple,
cheap, modular project that works in hard conditions for a long period of time
and has enough quality for a gig.

[https://medium.com/@leolorieri/underground-bands-get-more-
wa...](https://medium.com/@leolorieri/underground-bands-get-more-watts-for-
less-money-a8fdcdff98b0)

------
dbrgn
How would one best control the output volume on such a DIY amp? 2-channel
logarithmic 10K potentiometer in front of both inputs?

What if you use balanced input?

~~~
kazinator
If your input is balanced, it will be handled by some op-amp circuit or
whatever, which converts to single-ended internal signal, like the "balanced
line input module" shown in this page:

[http://sound.whsites.net/project30a.htm](http://sound.whsites.net/project30a.htm)

You can easily insert a volume control right after such a stage.

~~~
dbrgn
Yeah, but in the context of this article, I'd have to cut some traces on the
PCB to get there. Doesn't sound like the ideal solution to me :)

~~~
kazinator
Perhaps, perhaps not. The schematics don't seem to be available, but let's
imagine there is a stage in there which looks roughly like this:

    
    
        |\   C        |\
        | >--||-+-----| > 
        |/      |     |/
                <
                < R
                <
                |
                V
    
    

If we simply remove/desolder components C and R, we should be able to then
install hookup wires for a potentiometer (which includes the C also).

It looks like this particular board has tiny SMT components, which make this
sort of thing a pain in the but.

------
korethr
Interesting. I'm tempted to try this out. I have access to a quality soldering
iron and can use it decently well (I'm typing this on an ergodox keyboard I
built from a kit).

There is something very satisfying about building something yourself that you
get use out of every day. Such an amplifier is likely to fall into that
category for me.

------
comboy
Any DAC chip and some usb interface for it that you could recommend to go with
this?

And slightly OT, but does anybody know any ABX test of balanced input/output
signal? I find it hard to believe that there is a single person who can hear
the difference.

~~~
aidenn0
There are cases where the difference is huge; particularly when you have very
long runs between the preamp and the amp. This is on reason why you usually
see XLR inputs to monitors. Any noise induced is amplified and a long
unbalanced wire is a big antenna.

I've heard of cases where you could receive AM radio stations from such a
setup; I lean towards "urban legend" for that though. While it seems
theoretically possible (since many amplifier topologies can have resonance
when fed signals outside their expected operating range), it seems a bit
farfetched to actually end up with intelligible audio.

~~~
W-_-D
It's actually pretty common on older guitar amps. I've got a Marshall TMB
replica which has this issue when the guitar isn't plugged in. If you turn it
up loud enough, you can make out sentences clearly. I thought I was going
crazy when I first noticed it.

------
kunkurus
A DIY 0.0001% THD Amplifier: The MJR7-Mk5 Mosfet Power Amplifier
[http://www.renardson-audio.com/mjr7-mk5.html](http://www.renardson-
audio.com/mjr7-mk5.html)

------
jpmoral
>When I wrote my previous article, class-D audio was fairly new

Not sure what this means. I had a group undergrad project in 2002 to build and
characterise a class-D audio amp. The idea was well-established at the time.

------
aidenn0
On a similar note, anybody know why you can get a very good A/V receiver for
~$500 but not a pre/pro for under $1k? Is it just the lower manufacturing
volume?

------
KamiCrit
It's great that with some research and drive one can make something better and
cheaper than the engineered factory version.

Time well invested.

------
Scoundreller
I don’t build audio amplifiers often, but when I do, I always use top-quality
components like HPOO.

------
esaym
Hmm, I'd much rather build a Class-D amp from scratch with no chips
involved... any tips?

~~~
jacquesm
[https://www.elektormagazine.com/labs/200w-class-d-audio-
powe...](https://www.elektormagazine.com/labs/200w-class-d-audio-power-
amplifier-150511)

Not quite chipless but pretty close.

------
neuralRiot
there seems to be too many different thinghs mixed up, "professional
amplifier" "high end audio" and "class D" are three different worlds. It's
like a Humvee a Maybach and a Prius in the same vehicle.

------
WalterBright
What's the output power of the amp?

------
fermienrico
It is refreshing to see these types of articles.

Of all disciplines of human interests and hobbies, Audiophiles are one of the
most stubborn, misinformed, anecdotal and delusional bunch. Of course I am
generalizing, but every time I engage in a discussion about audio quality, it
is a losing battle. Not because of lack of data or supporting evidence, but
because of the fundamental dissent for data driven arguments. You cannot argue
reason when the first step is to be born with "audiophile ears".

Why is it hard to understand that we have sophisticated metrology and
instrumentation that can analyze things better than human ears can? I can
understand a separate discussion about personal opinions regarding how "warm"
a particular sound is, but that should remain distinctly as - _subjective_ and
that's perfectly OK.

It feels like the entire audio industry is promoting pseudoscience barring a
very few vendors that actually care. We have a $8500 mp3 player from Sony
claiming all kinds of things to the overwhelming abundance of cheap Shenzhen
exports. There is just so much noise.

I absolutely abhor audiophiles.

~~~
Karunamon
Of course they’re anecdotal - listening to music is a subjective experience.
If someone really thinks their music sounds better after adding $100 cable
lifters and taping $50 bags of rocks to their $10,000 system, _they are
automatically correct_. Their ears, their hobby.

It would be like saying that something can’t work because it’s a placebo -
even if all they’re getting is a sugar pill, if the symptoms went away, that’s
not really something that you can argue with.

I put audiophiles on the same level as sommeliers. The best wine is the one
that tastes best to the drinker. You can haul out your GCMS to test the wine
and your ABX testing software to test the audio and tell someone their
subjective experience is Wrong, but this misses the point. We’re not talking
about medical efficacy here, we’re talking about artwork.

~~~
TylerE
Please don't lump all audiophiles in with some sort of distorted (irony...)
stereotype.

I don't have a $10k system, or anything close to it, but yes, my system that I
put together for about $1000 is way way way way better than what you're
listening onm because I care enough to have a good external DAC, and feed that
into a good amp paired with either a set of decent used speakers or one of a
couple of sets of good headphones.

No "cable lifters" in sight.

~~~
sneak
Your external dac is indistinguishable to your ears from the internal one in
whatever device you are using to supply it with bits. This is precisely what
OP is talking about.

~~~
function_seven
There’s a huge gap in quality between most onboard DACs and externals. It’s
not necessarily because the onboard is worse at C-ing the Ds to the As, but
because they’re not isolated from the noisy electronics that share the power
supply.

My laptop emits different squeals when I scroll a window, for example.

~~~
Obi_Juan_Kenobi
That's just shitty grounding. Try putting one of those 3-to-2 prong adapters
on your charging cable and you'll see right away.

~~~
toast0
Shitty circuit layout maybe, but it's much easier to move the dac outside the
noisy box than to fix the cicuit layout. Most computers today can manage a
digital audio output, either through HDMI, spdif from the sound card, or via
USB. Keeping the analog path away from noise is sensible in a way that 96kHz
and oxygen free cables are not.

------
mnemotronic
{quote} ... I connected it to a pair of 30-year-old, three-way Panasonic
speakers, which I frequently use for testing.{/quote} Ummmm. I'm tempted to
dismiss the author's entire project based on that. Why not use a pair of
decent speakers or some high-end headphones like the Stax electrostatics or
Audeze planars? Weakest link in the chain and all that.

------
MrTonyD
I'm probably the only one with this opinion...but I sure miss the old days of
tube amps that weren't able to be highly accurate. They would roll-off the on
the high end, distort a bit all over, and gave a very warm and relaxing feel
to the albums I played obsessively. Now I've owned high-end tube and solid-
state gear, and the music hasn't sounded good for decades. Combine that with
the very limited bits provided by CDs, preventing any possibility of good
playback, and music has been completely destroyed. Old timers like me are
dying off, and most of the people who remember good music will be dead. Kind
of makes me sad.

~~~
mrob
>Combine that with the very limited bits provided by CDs, preventing any
possibility of good playback

16 bits gives you 96dB SNR (and subjectively more with dithering), which is
plenty at non-deafening listening volumes. It's more than even the highest
quality vinyl ever had. High bit depth is mostly useful so you've got some
headroom during editing.

~~~
pps43
16 bits give you 96 dB SNR only if your signal is one-bit. In a quiet room
with decent headphones set to comfortable level I can easily hear one-bit
flips in otherwise silent WAV file.

Not a problem for popular music that's consistently loud, but a real problem
for classical music with wide dynamic range.

~~~
mrob
I tried it and I couldn't hear it. Are you sure you got the endianness right
and it was really a least significant bit?

~~~
pps43
Yes, pretty sure. Had to zoom in a lot in audio editor to even see it. Could
hear it nevertheless.

It's important for the room to be quiet, as the sound is very faint and easily
masked, but it's there.

It's possible that Bluetooth headphones could lose it because of compression,
or cheap DAC in the sound card simply ignores least-significant bits.

