Mechano23 Open-source DIY Speaker Review

[amirm]

This is a review, listening tests and detailed measurements of the "Mechano23" open-source DIY speaker. A pair was kindly sent to me by the member. You can read more about it here.

Baltic birch cabinet seems quite solid and well above what you get commercially. I was surprised to see a tweeter with waveguide. Typical DIY speakers lack that.

Back panel has a port and nice speaker terminals:

Designer was kind enough to supply me with component list and costs:

And by the way, I added the components to the cart on the solen.ca (there are no Scan Speak nor SB Acoustis products on partsexpress) and the result was CA$144, i.e. CA$288/pair, see the list attached. Adding a port (which I didn't find) and a terminal I guess the total would have to be CA$300 (c.a. $220 assuming 0.73 exchange rate).

Regards,
Jarek

M23 components at solen.ca
Ind. 0.33mH link CA$5.10
Ind. 0.56mH link CA$6.73
Ind. 1.5mH link CA$10.58
Ind. 0.39mH link CA$5.81
Res. 12ohm link CA$0.41
Res. 15ohm link CA$0.41
Res. 8.2ohm link CA$0.41
Cap. 6.8uF link CA$2.39
Cap. 0.82uF link CA$6.09
Cap. 27uF link CA$1.73
Cap. 18uF link CA$6.39
Cap. 3.3uF link CA$1.41
Cap. 2.0uF link CA$2.48
Midwoofer SB Acoustics sb13pfcr25-4 link CA$34.44
Tweeter Scan Speak h26069200 link CA$59.75
Total: CA$144.13

Mechano23 Speaker Measurements
Not having looked at the thread here, I was so surprised and impressed by the frequency response:

Not only that, the directivity of the woofer and tweeter match almost perfectly -- something that even better designed commercial products miss. There is a resonance around 12.5 kHz which likely is not audible to many. Early window response is just as good:

Resulting in essentially perfect predicted in-room response!

Near-field measurements show the tweeter resonance and that of the port/cabinet:

The tweeter starts to beam above crossover frequency:

That should make it a bit less bright in highly reflective rooms.

Vertical directivity as usual indicates listening at tweeter axis:

Distortion was remarkably low at 86dBSPL:

I forgot to mention that the sensitivity is about 2 dB lower than average so you do need fair bit of power to drive the speaker.

Impedance is nominal 4.1 ohm which is typical:

Here are the waterfall and step responses:

Mechano23 Speaker Listening Tests
I guess I was so incredulous of the measurements that I did not think the speaker would not sound that good. Well, that good it was! The sound was impressively neutral yet warm with sufficient upper bass. Despite listening to a single speaker, I was able to almost satisfy my need for loudness. Pushed a bit harder and bass would become "papery" for the lack of a better word. The deep bass no longer sounded warm and accurate. One notch lower though and the response was superb with the speaker fully filling my huge listening space.

In my sub-bass reference track, those notes were produced with fair bit of distortion and at lower level. On other music with less isolated deep bass, there was no audible issue.

Overall, I was left just as impressed with subjective impression as I was with the objective measurements. You have a reference quality speaker here, albeit with limited deep bass response.

Conclusions
Innovation sometimes comes from unexpected places. Such is the case with Mechano23 speaker. Member @XMechanik has produced a masterpiece here. I can't think of a more optimized design in such a packaging and at such a reasonable cost. This is a speaker that you do not in any way apologize for. It rivals the best commercial speakers. Add to this the open-source nature of it and I can't think of more praise I can heap on it!!!

It is my pleasure to recommend the Mechano23 speaker design.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

 

[sam_adams]

Link to the ASR discussion of the Mechano23. Has all the deets.

 

[phoenixdogfan]

I didn't know Genelec was offering DIYs. As always, great review, Amir, and a great find as well.

 

[wwenze]

I wanted to say good and simple but turns out it has a crossover circuit more complicated than some $500 speakers. A lot of effort was put in particular using standard values; specific-value crossover parts are a pain to find for repair.

Also how is someone going to convince me this wasn't designed using a Klippel, looking at the DI graph.

albeit with limited deep bass response

IMO this isn't even that bad due to the shape of the curve, adding 10dB of boost can extend the bass to 40Hz. Output will be limited to 70+dB SPL but that's plenty for room use and it's a nice market option versus something with worse FR but higher power that will never be used.

Imagine if a better woofer was used.

 

[DWPress]

Off to read that thread now but being an ardent DIY speaker guy I'm very pleased this has done so well and @XMechanik gave it to the world.

Look for a big run on those drivers in the coming months.

 

[amirm]

Indeed you can't get deep bass response out of any small speaker like this from anyone.

 

[617]

Filter isn't that complex although I do agree it is more complex than many commercial offerings. Very nice execution and excellent driver choices.

 

[suttondesign]

would rounding the front edges improve any measured characteristic?

 

[Hart]

What an interesting week... a commercial speaker that looks home made and tests badly and an actual DIY speaker that looks pretty good and tests really well. It's an interesting hobby to be sure... Someone should mass produce these, it just really works well.

 

[Maiky76]

Here is my take on the EQ.
Please report your findings, positive or negative!

For the score rational your journey starts here
Explanation for the sub score
The following EQs are “anechoic” EQs to get the speaker right before room integration.
If you able to implement these EQs you must add EQ at LF for room integration, that is usually not optional… see hints there.

The raw data with corrected ER and PIR:

Score no EQ: 5.5
With Sub: 8.0

Spinorama with no EQ:

• Great effort
• Perfect for Home Theater?
• HF could be smoother
• Port limits?

Directivity:

Better stay at tweeter height
Horizontally, better toe-in the speakers by 10/15deg and have the axis crossing in front of the listening location, might help dosing the upper range.

EQ design:
I have generated two EQs. The APO config files are attached.

• The first one, labelled, LW is targeted at making the LW flat
• The second, labelled Score, starts with the first one and adds the score as an optimization variable.
• The EQs are designed in the context of regular stereo use i.e. domestic environment, no warranty is provided for a near field use in a studio environment although the LW might be better suited for this purpose.

Score EQ LW: 6.4
with sub: 8.4

Score EQ Score: 6.6
with sub: 8.7

Mechano23 DIY APO EQ LW 96000Hz
April282024-131103

Preamp: -3.5 dB

Filter 1: ON HPQ Fc 48.05,    0.00,    1.40
Filter 2: ON PK Fc 1976.74,    -1.28,    0.80
Filter 3: ON PK Fc 3663.47,    1.46,    0.55
Filter 4: ON PK Fc 9783.72,    2.60,    3.92
Filter 5: ON PK Fc 12003.15,    -1.51,    4.80

Mechano23 DIY APO EQ Score 96000Hz
April282024-131103

Preamp: -3.5 dB

Filter 1: ON HPQ Fc 48.05,    0.00,    1.40
Filter 2: ON PK Fc 2354.28,    -0.96,    1.60
Filter 3: ON PK Fc 2991.16,    1.46,    4.00
Filter 4: ON PK Fc 9690.54,    2.17,    3.22
Filter 5: ON PK Fc 12035.65,    -1.72,    4.12

Spinorama EQ LW

Spinorama EQ Score

Zoom PIR-LW-ON

Regression - Tonal

Radar no EQ vs EQ score
Minor improvements?

 

[amirm]

would rounding the front edges improve any measured characteristic?

Probably a bit:

You can see those two "shoots" above and below the main directivity area which are likely caused by diffractions.

 

[GXAlan]

Power is cheap. Subs are cheap. This seems like an incredible value. Just like other open source projects, you can have designs with fancier wood finishes, automotive paint, or Japanese lacquer finishes and get premium sound and the premium look.

 

[Mnyb]

The baffles are quite narrow . edge rounding should be at a fairly large radius to be worthwhile ?

Buts it’s DIY someone will surely do this to with slightly altered cabinet dimensions and subsequently tweaked filters to accommodate that .

But the original design smartly ticks so many of the 1000’s compromises needed to make a speaker at a certain price point and size . This a very attractive proposition. Impressive !

Add a sub and some cheap amp and go very reasonable priced hifi

 

[pierre]

Hello, I like the results a lot esp. for the price. I think i will build pairs, perfect for birthday presents
I let autoEQ look for how to perfect an already good pair of speakers. It generated 2 EQs one that optimise for a flat listening window and the second one that optimise for the "score" (details here).

                       asr     +sub
---------------+----------+--------+
default score  |     5.5  |     8.0 |
flat LW        |      6.4 |     8.5 |
opt score      |      6.8 |     8.8 |
---------------+----------+---------+

Preamp: -3.0 dB
Filter  1: ON PK Fc    60 Hz Gain +2.97 dB Q 0.98
Filter  2: ON PK Fc   454 Hz Gain -0.72 dB Q 2.96
Filter  3: ON PK Fc   522 Hz Gain +1.39 dB Q 2.91
Filter  4: ON PK Fc  2579 Hz Gain -1.43 dB Q 1.48
Filter  5: ON PK Fc  2964 Hz Gain +2.01 dB Q 2.99
Filter  6: ON PK Fc  9648 Hz Gain +2.08 dB Q 2.72
Filter  7: ON PK Fc 12301 Hz Gain -1.90 dB Q 2.20

As often, the autoEQ try to boost the bass to optimise for score. It will cost you 3db of max SPL. The small
PK that flatten the LW may or may not be useful: it depends too much on the quality of the measurement and reproducibility
between 2 boxes.

The second EQ graphs show some small but consistent improvements:

Note: spinorama.org is currently not updated due to some hardware failures and I am waiting for them to come. You can see recent measurements on dev.spinorama.org
but the JS is quiet broken at the moment due to me trying to optimise things but not having the time to do it properly.

 

[DanTheMan]

What an excellent speaker for very little money. I wish someone had designed something this nice when I was headed off to the dorm. Kudos to the designer(s?) and curse you (kidding of course) for giving me another project for the summer and another reason to anger my wife!

 

[TLEDDY]

OK… color me very (!) impressed. Our so-called amateur members never cease to delight and inform me, and here is another shining example.

THANK YOU!

 

[anphex]

Looking at this price and performance, speaker manufacturers are starting to have some explaining to do.

Imagine an ASR project for a full range tower speaker.

 

[MZKM]

Preference Rating
SCORE: 5.6
SCORE w/ sub: 8.0

Sensitivity: 85.2dB (300Hz-3kHz)
Frequency response: +/- 4.5dB 80Hz-20kHz

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[soundofsilence]

Has anyone ever reviewed Linkwitz designs?

 

[DanTheMan]

Has anyone ever reviewed Linkwitz designs?

Many people. They don't do that well unfortunately.