
Homemade Speakers - luu
http://www.chrisfenton.com/homemade-speakers/
======
beat
Complex crossover networks are The Devil. As you observed, the human ear is
largely insensitive to moderate variations in volume/frequency... but it's
_incredibly_ sensitive to phase. Phase is how we discern directionality
(stereo), among other things. So introducing complex phase shifts in the
crossover in order to achieve flatness is a bad tradeoff, imho.

To _my_ ears, the best and most musical sounding speakers I've heard have
time-aligned drivers and very simple crossovers. Tannoy, Spica, Vandersteen,
and other such designs are clearer and less fatiguing. I'm a musician and have
recorded numerous albums, and those speakers are the ones that match what I'm
used to hearing the best.

The fundamental problem is that we work on what we can measure. It's very easy
to measure frequency response. It's very hard to measure phase alignment. So
we fix what we can measure. If you want to see _serious_ map-over-territory
thinking, look at THD specs for amplifiers. It's super-easy to measure THD -
just isolate harmonics of a sine wave a 1khz. Unfortunately, this has
approximately zero to do with _music_ , unless your idea of "music" is static
sine waves. Recorded music has a 20-30db dynamic range (less in the case of
modern pop) and covers ten octaves. Dynamic recovery behavior, intermodulation
distortion, stuff like this is what gives amps their distinctive sounds - but
it's nearly impossible to measure! So they sell what looks good on paper...
THD. Sigh.

~~~
mbell
This comment covers much of what is wrong with common interpretations of
acoustics.

> the human ear is largely insensitive to moderate variations in
> volume/frequency... but it's incredibly sensitive to phase.

No, it's not. The human auditory system is sensitive to time variation. Phase
shift may contribute a time shift but only at frequencies low enough that
their wavelength has reasonably relation to the spacing of the ears. For
example at 10Khz the wavelength is _far_ too short for 'phase' to impact
arrival time. Ultimately what actually matters in this regard with the human
auditory response is group delay, not phase.

> Phase is how we discern directionality (stereo), among other things.

As mentioned above, what matters in the context of what your saying is group
delay, but that is far from the only thing that matters for directionality.
The human psycoscoutic system is very complex, part of directionality is group
delay, part of it is frequency attenuation caused by sound wrapping around the
ear from the ear, part of it is a half dozen other things. 'Phase' doesn't
come even close to being a catch all cause.

> To my ears, the best and most musical sounding speakers

And thus we've devolved from science, as this usually goes. What on earth does
'musical sounding speakers' even mean?

> It's very easy to measure frequency response. It's very hard to measure
> phase alignment.

I have no idea where you came up with this statement but it is very easy to
measure the response of a loudspeaker, both in amplitude and phase.

> If you want to see serious map-over-territory thinking, look at THD specs
> for amplifiers. It's super-easy to measure THD - just isolate harmonics of a
> sine wave a 1khz.

THD can be measured at only 1Khz, but it isn't something intrinsic to what
'THD' means. Measuring at only 1Khz is generally indicative of a crappy
amplifier manufacturer looking to inflate their power numbers. Proper specs
will provide a 20-20kHz THD rating.

> Dynamic recovery behavior, intermodulation distortion, stuff like this is
> what gives amps their distinctive sounds - but it's nearly impossible to
> measure!

If an amp has a distinctive sound, it has failed to achieve it's core design
goal. I'm not sure what you think is impossible to measure, but I assure you
it is not.

~~~
digitailor
Both your comments are heavyweight so I'm not trying to pick sides. (Sum your
two perspectives and I think you're close to Ultimate Expert Comment.) I just
want to mention that beat is talking about phase alignment _between identical
signals_ , which our perceptual network is incredibly sensitive to. Anyone who
has ever done multi-mic recording can attest to the very real effect you can
hear from lack of phase alignment, even if they have bronze ears. Even worse
is if you duplicate two musical recordings and offset one, even by a tiny
amount.

This is a critical aspect of crossovers- since they contain the same signal,
any phase differences between the intersecting components are easy to pick up
by the ear and very difficult to measure since it won't show up as a
significant frequency or amplitude differential. In the highly acoustically
sensitive area where the crossover occurs, the phase distortion between the
two signals is hard to pin down but it's definitely there, it's easy to hear
by A/Bing.

I mix on a multiple-monitor setup and the one that is most critical to me
sounds like absolute garbage. However, it has a wonderfully "flat" response
and allows you to get an idea of what proven aesthetically-unpleasing issues
are present. It has no crossover. The goal is not to have perceived rumble,
tinniness, or mud on any of the incredibly wide range of listening systems out
there. I think this is what beat means by "musical"\- flat speakers are
actually not pleasant to the ears, but the most empirically useful.

The most famous secret of many respected mix engineers is the Auratone.
Michael Jackson's "Bad" was mostly mixed on this little thing. It sounds like
absolute garbage aesthetically but reveals more issues in a mix than anything
else. It's like when you first saw things under a "blacklight" as a kid and
got to see all the particulate matter covering everything, that you can't see
with the naked eye.

Here's more about the Auratone. I hope my comment has helped to bridge this
critical area of "musicality" vs. empiricism.
[http://www.trustmeimascientist.com/2012/02/06/auratone-
avant...](http://www.trustmeimascientist.com/2012/02/06/auratone-avantone-
behritone-review/)

Postscript- the listening environment is the most important aspect! Always!
You can have the best mastering grade monitors on earth in an improperly
treated room, and it's all for naught!

~~~
mbell
> I just want to mention that beat is talking about phase alignment between
> identical signals, which our perceptual network is incredibly sensitive to.

I wouldn't go that far. If you have two signals emitting from physically
separate location and they are out of phase, you just get comb filtering. Is
it audible? It can be, but its not the phase you're hearing, it's the drastic
frequency notching in amplitude. More importantly, you're going to get comb
filtering no matter what you do with a multi-speaker setup. Just move your
head a couple inches out of the ideal sweet spot equidistance from each
speaker and you'll have created an effective phase shift and get the same type
of comb filtering. In other words even with a theoretically perfect pair of
time aligned speakers with perfect cross-overs, you'll still get comb
filtering if you take various measurements around the listening area. Just
moving the mic 4 inches can have drastic effects on the measured response.
Incidentally if you've ever seen someone taking a measurement with a sound
meter and rhythmically moving the mic around in a strange fashion, they are
doing that to try to even the effects of comb filtering.

> This is a critical aspect of crossovers- since they contain the same signal,
> any phase differences between the intersecting components are easy to pick
> up by the ear and very difficult to measure since it won't show up as a
> frequency or amplitude differential.

If you're taking a measurement in the crossover region and there is a phase
shift between the drivers you most certainly will see an effect in amplitude
as you'll have at least partial wave cancellation. You can certainly take
measurements in locations what won't show this, but that is always true. You
can take measurements of a perfectly time aligned speaker that make it look
like it has phase issues too, if you put the mic in the right spot.

Likely the largest improvement you get from time alignment of the drivers in a
multi-way speaker is the ability to control vertical lobe tilting, but you can
'fix' that issue with MTM layouts without time aligning the drivers as well.

~~~
lcrs
I think what one might crudely call the "audiophile phase beef" is not about
the comb-filtering that results from misalignment but the non-linear phase
response of most crossovers, before the signal hits the air. Most act somewhat
like an all-pass filter: a flat frequency response but varying delay across
the frequency spectrum. This doesn't affect frequency sweeps or white noise,
but results in impulses and clicks being smeared out in time or ringing a bit.
The thought among some is that this is audible on percussion sounds, but
experimental evidence is dubious as far as I can see. There are some
references in the classic Douglas Self crossover book:
[http://books.google.co.uk/books?id=D9l6JWKKSzUC&lpg=SA2-PA14...](http://books.google.co.uk/books?id=D9l6JWKKSzUC&lpg=SA2-PA14&ots=wEtgaIUCgH&pg=SA2-PA22#v=onepage&q&f=false)

A similar argument which I think more people would agree with is that reflex-
loading a speaker hurts the low-frequency group delay, the lack of which is
one reason suggested for the supposed clarity of the classic NS10 monitor:
[http://www.soundonsound.com/sos/sep08/articles/yamahans10.ht...](http://www.soundonsound.com/sos/sep08/articles/yamahans10.htm)

------
matthew-wegner
Ah, DIY speakers! The general rule here is that DIY speakers will sound as
good as commercial speakers that cost 4-5x as much. You can buy kits with pre-
cut parts, so all you need to do is glue/clamp and build the crossovers.

Easy-to-build bookshelf speakers, the Overnight Sensations--$136 with free
shipping: [http://www.parts-express.com/overnight-sensations-mt-
speaker...](http://www.parts-express.com/overnight-sensations-mt-speaker-kit-
pair--300-706)

And the Amiga towers are great for a living room, more towards $300 for the
pair: [http://www.diysoundgroup.com/speaker-kits/amiga-
kit.html](http://www.diysoundgroup.com/speaker-kits/amiga-kit.html)

More Amiga info:
[https://sites.google.com/site/undefinition/diy/amiga](https://sites.google.com/site/undefinition/diy/amiga)

I have built both, they're both really great at what they do. If I ever have
the free time and money, I'd love to build some Statements:
[http://speakerdesignworks.com/Statements.html](http://speakerdesignworks.com/Statements.html)

~~~
kingnight
Is that general rule pretty accurate? I've been contemplating buying an home
speaker upgrade and pretty price adverse because I don't _need_ to upgrade. I
am currently using Harman Kardon Soundsticks II w/ sub for my home audio and
have no complaints -- kept this for 8 years really, so maybe I don't know what
I'm missing. Are those 300 really ~ to $1200. If so, that sounds like a solid
project!

~~~
matthew-wegner
I'd say so! Most of my information comes from a super-long 3000-post speaker
thread on a private music site. I have auditioned a few high-end speakers in
stores and would say that DIY holds its own very well.

Personally, I replaced an ~$800 pair of speakers with the Amigas, and they're
_vastly_ better in terms of clarity/resolution. I have a decent tube amplifier
already.

Past that point I'm pretty sure room setup/room treatment starts to matter
much more than hardware...

~~~
andy_ppp
Which tube amp do you have (or should I buy?). I'm in the market for one :-)

~~~
matthew-wegner
I have a Yaqin MC 10L: [http://www.ebay.com/itm/YAQIN-MC-10L-Push-Pull-
Integrated-St...](http://www.ebay.com/itm/YAQIN-MC-10L-Push-Pull-Integrated-
Stereo-Tube-Amplifier-/141323298889)

With aftermarket tubes: [http://psvanetube.com/wordpress/purchase/shuguang-
treasure-s...](http://psvanetube.com/wordpress/purchase/shuguang-treasure-
series-vacuum-tubes/)

The amp is _super_ heavy (40+ lbs), so shipping is expensive.

I like it a lot--definitely changes the sound to something warmer. It's also a
beautiful object, especially in the dark. The aftermarket tubes helped resolve
bass, but are probably overkill (I used them as a reward to myself for crunch
on a contract gig).

Note that tube amps have a lot of downsides--you can't leave them on 24/7,
they make a lot of heat (so can't stack with other electronics), you need to
tune voltage during the first few months of operation, only stereo output with
minimal AV switching, etc...

~~~
kingnight
Thanks for the info!

------
ljlukkar
I have degree in computer science but I owe a large part of what I understand
about physics and electronics to my speaker building hobby. I highly recommend
getting into the physics of sound. It’s actually pretty simple and will teach
you how waves behave in general.

[http://www.cs.helsinki.fi/u/ljlukkar/labsub/](http://www.cs.helsinki.fi/u/ljlukkar/labsub/)

I’m currently working on a Arduino based pre amp that hosts a rest api for
remote controlling:
[http://tinypic.com/r/15yvj2g/8](http://tinypic.com/r/15yvj2g/8)
[http://tinypic.com/r/11vmhld/8](http://tinypic.com/r/11vmhld/8)
[http://tinypic.com/r/jrzfk5/8](http://tinypic.com/r/jrzfk5/8)

~~~
mikevm
So how do you get into the physics of sound?

I don't think I'll be building speakers anytime soon though, but I'm still
very much interested in the details of psychoacoustics and sound reproduction.

~~~
jacquesm
Start by reading this:

[http://www.amazon.com/Acoustical-Foundations-Music-Second-
Ed...](http://www.amazon.com/Acoustical-Foundations-Music-Second-
Edition/dp/0393090965)

------
stcredzero
Yay! Audio knowledge! I've met so-called "geeks" who will look at you funny if
you start talking about "frequency response" \-- but they'll talk your ear off
if you remind them about the frequency domain and Fourier Transforms. Back in
the late 20th century, just about everyone who was tech savvy seemed to know
some basics about sound. Nowadays, I wonder if the whole Monster
Cable/coathanger thing has made some people filter out everything sounding
like audio knowledge as "woo." Not all of it is. A lot of it is physics.

Back in the 80's, designing and building your own speakers was a suitable
project for high school students. Still is.

~~~
minimax
Maybe for CS "geeks" but for those of us who came up through the EE ranks
linear systems is our bread and butter.

------
scoot
Those aren't homemade speakers, they're homemade enclosures. Disappointed as I
was expecting something more substantial than "I made a box".

~~~
mbenjaminsmith
DIY speakers as a hobby is mostly about enclosures and crossover networks.
It's quite rare that people would build their own speakers drivers (some
planar speakers being an exception).

Where it's rewarding is taking available drivers and building a full speaker
around them -- usually optimizing for performance vs cost. It's difficult and
expensive to build really high quality loudspeakers. Add markup to that and
the retail price of a well engineered speaker will quickly go into 5 digits.

The speakers in my living room are DIY (though they don't really look "DIY" as
far as that might carry negative connotations) and they're an excellent value.
They were also fun to build. In no way was I disappointed afterwards because I
had not, say, wound the voice coils myself.

------
chrissnell
So how did he design them? What tools does one use to do this? I have a form
factor in mind for some speakers that I'd like to build for my off-road truck
[1]. I have a certain look and mounting style in mind and I haven't seen
anything like it. I just don't know where to start with the design, though.

[1] [https://flic.kr/p/o1xmJ8](https://flic.kr/p/o1xmJ8)

~~~
Anechoic
In addition to what jzwinck recommended, I'd also recommend the Loudspeaker
Design Cookbook [0] and the Master Handbook of Acoustics [1]

If you're an engineer that's comfortable with differential calculus, I'd
recommend the grandaddy of them all: _Acoustics_ by Beranek [2] (I'm actually
linking to _Acoustics: Sound Fields and Transducers_ which is an updated
version of Beranek's original _Acoustics_ cowritten with Tim Mellow)

[0] [http://www.amazon.com/Loudspeaker-Design-Cookbook-Vance-
Dick...](http://www.amazon.com/Loudspeaker-Design-Cookbook-Vance-
Dickason/dp/1882580478/)

[1] [http://www.amazon.com/Master-Handbook-Acoustics-Alton-
Everes...](http://www.amazon.com/Master-Handbook-Acoustics-Alton-
Everest/dp/0071603328/)

[2] [http://www.amazon.com/Acoustics-Transducers-Leo-L-
Beranek/dp...](http://www.amazon.com/Acoustics-Transducers-Leo-L-
Beranek/dp/0123914213/)

------
snowwindwaves
here is another interesting tale of home-made speakers, this fellow made some
very large boxes and had very specific drivers he wanted but they were still
inexpensive. He used active (powered as opposed to passive RLC network)
crossovers. Also he built his own off-grid house with mini-hydro plant. the OP
will probably find it interesting. I ended up reading every page on this
fellows 90's style website.

[http://ludens.cl/Electron/Speakers/speakers.html](http://ludens.cl/Electron/Speakers/speakers.html)

~~~
Theodores
> "While commercial musical equipment is usually of quite usable quality,
> commercial speakers unfortunately are not, unless you go to exotic and
> extremely expensive brands. The reason is simple: Good speakers, by law of
> physics, need to be large. There is no way around this basic fact."

Is this as true as it was in the 1990's?

A lot of people have high-end small speaker systems with branding such as
'Bose' on the front. Maybe they have got old and their ears have changed, but
even if they once had big-box speakers due to the physics reasons, they have
moved to the small speaker 5.1 things and it is now okay to do that. The sub-
woofer doesn't have to be stereo either.

I don't know, but has new thinking fundamentally changed how hi-fi is done
from the twin speaker stacks of old with lots of tweeters/woofers/crossovers
to these new-fangled mini-5.1 things?

~~~
VLM
Low frequency response needs size. If you're willing to cutoff at 200 Hz then
little stuff will work. In my high school years I built a stereotypical mono
subwoofer of the 2x4 sheet of plywood for front and back variety. Sounded
pretty good, but could have been better.

A mantra thats repeated continuously, mostly by people selling mono subwoofers
or uninterested in audio reproduction, is low freqs are non-directional.

Yet I go outside and listen to thunderstorms and passing unmuffled motorcycles
and firearms and much bigger .mil weaponry and it sounds highly directional. I
can point at the rumble of distant artillery as well as any other sound.

Surely if you build a directional subwoofer system and can only perceive a
field, that'll work OK even if its an economic financial fail. But the other
way around is an epic fail. So save money at the risk of sounding bad. Well,
if the point is spending money to sound good, having an extra 3 dB of signal
is never a loss...

Another puzzle is I know from experience that L-R and L+R sound different from
FM subcarrier detection. Supposedly mono subwoofer people claim that magically
only applies to higher freqs. I would think a single mono channel subwoofer
would sound "better" fed off only L or R channel than some peculiar mix of
unknown phase. The problem is which channel to connect to?

Phase relationships are a pretty big puzzle in audio once you get past simple
response problems and simple distortion problems.

~~~
dankoss
All sound waves are directional, but the point made by acousticians is that in
any enclosed space with dimensions smaller than the wavelength in question (56
feet for 20Hz), low frequencies are effectively non-directional because they
fill the entire space (with nulls at various points). The wavelength of high
frequencies means you can orient their direction in the room.

Of course you won't hear this outdoors because the sounds are not in an
enclosed space.

------
keehun
Does anyone know if this is a graduate level course? Seems like working with
JBL engineers and getting mentored by TH is something that would draw a big
crowd.

------
kiram9
If anyone is thinking to build their own cabinets - I would suggest checking
out [https://www.parts-express.com/cat/speaker-
components/4](https://www.parts-express.com/cat/speaker-components/4) I have
built a few speakers from scratch, including line arrays using them as my
source. They are kind of like the mono price of speaker parts.

------
jensC
A friend of mine created an online app that helps calculating Loudspeaker
Enclosures. The app is completely free, no registration necessary.

[http://micka.de/org/en/index.php](http://micka.de/org/en/index.php)

Hope that someone finds this useful.

------
beloch
I once had a prof who designed his own speakers and built them out of
concrete. They were massive, full-range beasts that were flat down to 20 Hz.
(in the right room). As it turns out, concrete is surprisingly good speaker
material, aside from the near total lack or portability. Some crazy (and crazy
rich) audiophile bought them for $50K. Selling slabs of concrete for $50K a
pop sounds like a great business model, but there is a severely limited number
of people willing to pay that much for speakers, and the speakers apparently
took hundreds of hours of tweaking to work "properly" anyways.

~~~
thrownaway2424
"In the right room" is important. Anyone who spent $50k on loudspeakers ought
already to have spent an equal amount on room geometry and materials. In fact
above a fairly modest amount (a few thousand bucks, maybe) most people will
get superior results from changing the room, rather than spending more on the
equipment.

------
msandford
If you want to go really nuts, take a look at the Elsinore by Joe Rasmussen:
[http://www.customanalogue.com/elsinore/elsinore_index.htm](http://www.customanalogue.com/elsinore/elsinore_index.htm)

He does a great job of designing a crossover and phase-inverting the tweeter
to get an excellent step response. beat mentions that this is something most
speaker manufacturers fail to account for.

It's about as good as you're going to get for a DIY design and a whole
associated design guide.

------
timclark
[http://www.theregister.co.uk/2014/07/02/feature_the_future_l...](http://www.theregister.co.uk/2014/07/02/feature_the_future_loudspeaker_design)
\- has an interesting perspective on speaker design and the human auditory
system.

------
laurentoget
i read several claims that you can buy components and blueprints and build
yourself speakers which would be much better than what you could buy for the
price. this sounds like a business opportunity to me. anybody knows why nobody
is selling good speakers for less?

~~~
vl
Generally speaking, if you thought of something obvious, search the internet,
somebody is already doing it. For example -
[http://www.htd.com/](http://www.htd.com/) \- and godzillion other.

------
givan
This is only a box for speakers, I was expecting something more.

~~~
analog31
Ah, but the box is a big deal. I'm a DIY speaker builder, but for musical
instrument rather than hi-fi use. The box is an integral part of the
electromechanical system that determines the response (and to some extent
power handling) of the speaker at low frequencies. The box may be a plain box
whose volume is its main parameter, or may contain other structures such as
resonant ports.

Most woofers are designed so they have to be in an appropriate box in order to
be useful. Without access to the process for designing custom woofers, the
DIY'er has at our disposal two main variables for tailoring low frequency
response: Woofer choice from off the shelf models, and box design. And there
are some tradeoffs to manage, such as low frequency response and box size, so
that there's no ideal box design for all uses.

~~~
chillingeffect
> musical instrument rather than hi-fi use

Me, too. Just when speaker design seemed to be a solved problem, with a small
set of uniform solutions, up springs the concept of co-designing speakers and
musical instruments.

What frequency range/instrument are you working with? And what
architecture/horns/boxes/tubes/drivers?

~~~
analog31
Sorry, I left town right after posting that. I'm a bassist, so it's 40 Hz up
into the midrange, with not that much going on in the tweeter zone. So far my
designs are just lightweight "pro audio" drivers in ported boxes. Nothing
sophisticated, but I just want to be in control of how my speakers work.

Interestingly enough, I think that the electric bass involves a sort of de
facto co-design, because the bass acquired its "classic tone" during a time
when speakers were relatively low performance, i.e, having -3 dB points far
above the lowest fundamental. To this day, speakers with that tone quality
tend to be preferred by bassists, which is a fortuitous circumstance because
it liberates us from dragging around huge boxes capable of actually
reproducing that E fundamental at full strength.

------
justatdotin
consider digital crossover from minidsp. I've made a pair of powered 2-ways
with a minidsp/miniamp combo in each.

------
gcb0
anyone who pays more than 200 on Chinese speakers at bestbuy are the bane of
my existence. they drive everything up. and then publish tons of unscientific
reviews and technobabble to justify their silly spending.

