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DIY 3 way floorstanding speaker

Hifi sound at an almost unbeatable price/performance range.
Max budget: 350/speaker

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Quality sound from the ground up is the slogan, where the target area is medium sized living rooms (< 50m2)

As of recently I got a measurement mic, so i can almost properly design a speaker now (including room simulation and compensation), and since I have some experience with 2 way designs, I thought: why not go a step further by going 3-way? Hence why I started this project.

The lows are supplied by a 8" driver
The mid/high range is a 4" done
Where the highs are done by a 20mm dome tweeter
Most of the hard work is done, designing and assembling a pair of solid enclosures, crossover design, and initial testing

It took me quite some measurements and total reworks of this system to get the response as it is now. (also quite the budget, over 2000 euro total for sure)

The total THD is an average of 8% (measured by Room eq wizard) in my room with my home cinema amp, receiver and the only damping being on the backside of my mic.

featuring a 8inch woofer with large xmax (12mm) and a 4" midrange driver with flat frequency response, combined with a softdome tweeter for the finishing touch.

The woofer has a T-line ported enclosure and goes as low as 25HZ

Specs:
Frequency response: 25-25000HZ
Recommended amplifier power: up to 180 watt RMS
Max amplifier power: 225W (peak)
Impedance: 4 Ohms

BOM (single speaker):
woofer: 1x Tangband W8-1363SBF- €95
mid/highrange: 1x Dayton RS100-4 €32
tweeter: 1x Dayton ND20FA-6 - €18
filter pcb: €15
filter components: €35
terminal: square with gold plated contacts - €10
cabling internal: 4m 2x2.50mm - €6
filling: 40L lamb wool - €20
standoffs/feet: €15
22mm multiplex wood: 1x 244x122cm - €40
woodglue: €5
paint: €15
screws: €15
sealing tape: €10



Total: €327

  • update 6-1: why the box i have goes this low

    Ramon Schepers07/13/2017 at 17:29 0 comments

    for those wondering why my speaker goes to 20hz with ease:
    it looks like a huge slot ported design, but it is in fact a transmission line enclosure (t-line for short)
    configured at around 45hz tuning with my woofer in it.
    okay, 45hz is still no 20hz.



    lets dive a bit more into detail here:
    which includes the frequency of sound (340meter per second)
    i don't know it exactly in detail, but will try to explain it in a simple form.



    the full frequency wavelength of 45hz is 7.5 meters.



    now divide that by 4 so we get a quarter wavelength, the result: 1.888meter
    note that this is for a bass cannon like system,
    where a t-line works with a quarter of that, so divide the 7.5meter by 4 (1.888meter)



    also, a t line usually can go a octave lower than it's tuning frequency with ease, so in this case: 22.5hz instead of 45hz!



    anyhow, we got 1.888meter of port length needed to reach that frequency
    the port's minimum square cm diameter needs to match the woofer's and the 'initial' chamber needs to be treated as ifit were a closed type (because we're going t-line).
    i personally chose a rather large 'initial' chamber area of around 28 liters so i can apply lots of dampening wool to eliminate resonances
    that with a 1.888meter port goes to the 22.5hz we need, but i don't use a 2.125meter port at all, i use one of 1.3meter. (a bit over the half of that!)



    how i got down to the 20hz remains a mystery...



    ...



    ...



    ...



    found a solution yet?



    ...



    ...



    not yet? lemme explain how i achieved it! :D



    the port has resonances as well, so we need dampening in the slightly wider point of the port (to eliminate those)
    this also acts as a extra air resistance, resulting in a 'simulated longer port'. (which turns out to be what i needed luckily!)



    before the dampening the woofer was moving like crazy below 20hz (meaning we're under initial tuning frequency of 55hz / 2 = 27,5hz (7.5hz under tuning frequency))
    after the dampening the simulated port length did get to the result as it were now (i stuffed one sheet of lambs wool for a 10l enclosure just before the end of the port, just out of sight)



    and voila, we get to 22.5hz with ease now!
    also, the dampening wool helps limiting the woofer's movement on the very low end as well, meaning it doesn't get over it's xmax (of a whopping 12mm!) at it's rms power (150w) until we get to 17hz or lower.



    so in theory, the speaker goes from 18hz up to over 20000hz, but for safe margins i'd say: don't go under 25hz at high volumes (especially over the total rms power of 200w)



    now you know how i got to around 20hz when i tuned my enclosure to 45hz




    notes regarding this update:
    i literrally tried to keep it as simple as i could, and left out some (maybe important) information.
    there are alot of ofther paramets involved, like the port's internal resonances (i also explained how i eliminated those), even air temperature affects the speed of sound (so i went for the default of 340m/s)!



    and here is one important thing: try to get your woofer's resonance frequency to get close or alighed to your t-line tuning frequency (i made the mistake for this build)



    i don't give any warranty when you do something wrong with these tips and blow something up, so please use this information at your own risk!



    it might take some trial and error, just like me.



    most importantly: enjoy building! :)




    usefull links



    calculate wavelengths:
    http://www.procato.com/calculator-wavelength-frequency/



    note names (for checking your tuning frequency):
    http://www.sengpielaudio.com/calculator-notenames.htm



    for the lazy t-line box designer: (lazy is good, although i do it mostly manually except for the 2 links above)
    http://dbdynamixaudio.com/quarter-wave-flared-vent-t-line-horn-bass-reflex-enclosure-calculator/

  • update 6: getting closer to flat response!

    Ramon Schepers07/11/2017 at 15:05 0 comments

    hi all, took me quite a while for a update, hm?

    it's because i felt more into pc's instead of audio lately.

    i have been considering ditching this whole project quite a bit, and nearly made the step to buy pre fab speakers. the thing that was holding me bakc was the project on here :)

    and i'm glad i continued the project.

    here's why:

    i just resumed working on the crossover, basically i got a very smooth response curve (even including my room's resonance frequencies!)

    the speaker is basically the same as in the last update, so it's not worth showing.

    the frequency response:

    as you can see, i got it smooth from the lower mids and up, only need to work on the woofer's crossover (maybe increasing the frequency of it's low pass filter and notch the 100hz out a bit?)

    also, low extention is rather nice in this speaker, thanks to the t-line design.

    max output is rather low, especially for it's size: 103DBC at 200 Watts RMS (music, not a constant tone)

    which means it is about 80DBC at 1 watt at 1 meter when playing music

    now, i know these values don't mean much for musicality (how 'good' they sound)

    but i can assure you this: they sound very nice and transparant, although the very lows (20-40hz) sound a bit compressed somehow.

    i honestly suspect my amplifier (behringer a500) to not have enough juice to push it on the very low frequencies, so in the future i might go search for a more powerful amp, or go for bi-amping.

    right now i was playing a single speaker (mono) and it sounded like there were multiple speakers alongside with it, as it had a very wide soundstage, which surprised me.

    i sat 3.2 meter away from the speaker, with my ears the same height as the tweeters, and when i turned one of my ears towards the tweeter, i barely could locate it, which means it has a very good sound dispertion. (although some might not like this)

    the sound is tight and responsive too in my opionion.

    i also measured the frequency response with my multimeter (not the most ideal way, but it does the job), the result? about 4.5 ohms

    the specs right now:

    200w rms (can go up to 220w rms, just need to increase voltage ratings on some caps)

    frequency response: 25-23000hz

    sensitivity: 80DB

    impedance: 4OHM

    target rooms: mid sized living rooms which barely have place for a subwoofer, and don't need too loud sound,

    main intended use: watching movies

    future plans:

    once i get the crossover completely right:

    first swap the crossover parts for better quality ones.

    test again.

    design custom pcb's and order the pcb's at OSHPARK (most probably 0.8mm, 2oz, 2 layer)

    once i receive those, assemble one and test

    if all succeeded:

    assemble the final speakers and make them look nice.

    oh well, that's it for this update, check you guys layer :)

  • update 5: reworking the design again

    Ramon Schepers05/06/2017 at 19:32 0 comments

    i made quite some progress since last update, which i sadly forgot to documentate

    but the efficiency was reduced by like alot (80DB @2.83V @1meter ain't that much) which i couldn't figure out why.

    then i realized i had the woofer going up to much regarding frequencies, and the tweeter rolled off too much at 12khz already.

    this made me rethink the design around the existing enclosur, because it'll be spilled wood if i don't use them.

    so i ordered new crossover parts, and changed (back) to the more accurate (and lower THD) Tangband W4-1320SIF which i originally intended for this project.

    I changed the tweeter for the Dayton Audiop ND20FB­4 Rear­Mount 3/4" Neodymium Dome Tweeter which has a smoother response curve.

    Next i designed a bare bones crossover (of only 4 parts) with existing parts in my lab to filter a bit, hooked everything up, and tested the whole thing.

    the results were quite smooth already! but below 800HZ the response was dipping about 6DB, this is bacause phase cancellation of midrange and woofer.

    but this is logicaldue to the components used (woofer lpf: 1khz, mid hpf: 300hz)

    so new crossover parts are ordered to cross the woofer and fulltange 4" driver at about 400HZ.

    Aside from crossover talk, i needed new tweeter holders as well, as the new tweeters are rearmounted.

    so i opened up sketchup again and made a very simple design, and ordered at my fave 3D hub at 3dhubs. :)

    Now to wait till the crossover parts and tweeter holders arrive.

    I also measured the output level at 2.83V, 1000hz again, and got a little over 90 @ 1 meter distance, i'm quite pleased with this.

    photo of the WIP speaker righ now:


  • update 4

    Ramon Schepers03/08/2017 at 21:53 0 comments

    i measured again and again, wondering if i could reduce the bass, then i realized that the speaker was within 1.5 meter of a corner, meaning that the bass resonates in that corner and boosts it.

    so i placed the setup in the middle of my roon and the results are pleasing. not just a bit, but alot.

    also, seems i don't have a c weighted decibell meter, but an a weighted one, so i had to get that calibration off, plus finally calabrated my laptop's soundcard as wel.

    (drums)

    behold, the actual response:

    the total harmonic distortion (THD) is an average of about 4% at high volume (peaks at 10% at about 100hz) with my crappy amplifier (renkforce mp-2000)

    on a side note: midrange waveguides and tweeter holders have been ordered too (long live 3dhubs and the people who have listed their printer there) :)

  • update 3: high volume test

    Ramon Schepers03/03/2017 at 18:36 0 comments

    so i decided to close air leaks in the enclosure, put the midrange driver in it's sealed compatiment (not fitting properly yet) and measured again (this time at high colume).

    all i can say is that my room was resonating at some bassy point, so the bass response is rather ugly and boosted..

    also got to fix the frequency dip at 500, 1500 and 3000hz. :)

    pic of the speaker as is below:

    notes regarding to the pic:

    yes i sanded some away, as it was a bit too tight to get the wooferi n there

    the midrange isn't mounted yet, i will design a waveguide for it and 3D print it at 3dhubs or something similar, same goes for the tweeter holder, i think i'm going for a bullet-design (not like a bullet tweeter, but letting it look like an actual huge sized bullet!)

    note: i just ordered the crossover pcb's at oshpark =)

    note2: the maximum volume i was able to get is 101DB (c weighted) when playing music at 200W rms (was breaking the speakers in a little while measuring)

    what i need to do:

    order new crossover parts (used parts for 2 crossover in one crossover right now)

    assemble crossover

    design waveguide for midrange

    3d print tweeter holder (already designed! :D )

    the frequency response as it is now:

  • update 2

    Ramon Schepers03/01/2017 at 22:20 0 comments

    i just replaced the ugly looking mcvoice tt-130 with a slightly smaller, but better looking dayton audio rs100-4 midrange.



    i then measured and found out there watch a dip in the frequency response at 1khz, so i applied a double lowpass filter (from 6db to 12db) on the woofer, and poof! the dip is away now :)



    the result is pretty much the same in response, but it just looks nicer in overal now.

    measured freq response (1m distance) included.

    note that i did 1/12 oct smoothing, for a better view of response details.

    also extended the frequency response to 15hz for this measurement

  • update 1

    Ramon Schepers03/01/2017 at 18:53 0 comments

    hey all, just wanting to say that i've been busy with getting as less room inteference while measuring as i can, meaning i have a half dome around the calibration mic to prevent backwards reflextions being captured.

    also, this seems to have reduced the 100hz boost in the design as well.

    fun facts i didn't know:

    the speaker goesas low as 25hz (i guess that's thanks to the t-line enclosure?)

    the db smoothing is based on the average (1/3th octave smoothing) in the image below

    note that my room can be pretty noisy (fridge, 1 laptop and 1pc running), so the THD is measured at about 10% (seems a bit high to me)

    extra notes: the image says no smoothing, while i have applied 1/3oct smoothing(!)

    the dac used is my laptop's built in soundcard (set at 96khz, 24bit)

    the amplifier used is a mccrypt mp2000 (45w / 4ohm at < 1% THD one channel)

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