The uglings: Mechano24

[XMechanik]

Asymmetrical driver placement has always seemed visually unappealing to me, but I tried it in my previous (3-way) design and noticed some advantages. So I used this approach again, this time with a 2-way design, and… omg, what an eyesore. What do I to do with it? Maybe a little manipulation of the picture frame, moving the units away from the camera, bringing curves and slopes of the stands to the foreground, a bit of overexposure... ok, here they are.

Mechano24:

Enclosure dimensions: HxWxD: 290x174x263mm, polyester fiber filling.

18mm birch plywood, front panel glued "on top".


Rear panel flushed into the enclosure.


Bass reflex 8l, 45Hz. BR tunnel made of a piece of HDF glued on slats.


Crossovers assembled on a plywood scrap, attached with screws on an anti-vibration pad to the rear panel (installation through the woofer mounting hole).


Crossover schematic and the characteristics (rating 6.78/EQ9 6.133/EQ10)


THD measurements: ~1.4% peak at 2kHz (87dB/1m)


The design is based on ScanSpeak drivers:

• D2608_913000
• 12W4524G00

 

[XMechanik]

A little summary. Some time ago I made an attempt to build speakers that would have flat on-axis characteristics and linear PR, In-room, ER, etc. characteristics. The design besed on 13cm Satori driver and a regular Seas dome. Achieving the goal turned out to be difficult. The only way that I found to get closer to the target was rising the crossover frequency to a strange level of 5kHz. On the other hand, the sound I got from the speakers seemed a way better than what I had created before. The question arose what would be a simple and effective method to obtain dBspl and CTA linearity at more reasonable crossover frequencies? The Mechano line is experimental testing of various inexpensive options.
So a little summary. I don't know how much it's worth because the designs may be too different to draw final conclusions. Anyway, if anyone would like to take a look, here it is.

Id	Nr of ways	Directivity matching method	Crossover frequency	CTA	Midwoofer diameter	Tweeter	Midwoofer	design link*	matrix pos.
Mechano	2	None	5kHz		13cm	Seas H1396-4	Satori MW13P-4	None	B2C3
Mechano22	2	integrated WG​	3.6kHz		13.5cm	Dayton ND25FW-4	Dayton DSA135-8	link	A3B3
Mechano23	2	integrated horn	3.4kHz		15cm	ScanSpeak H2606/920000	SB-Acoustics SB13PFCR25-4	link	A2C2
Paper cone (not "promoted" to Mechano line)	2	large tweeter diameter (6cm)	4kHz		12cm	Monacor HT-22/8	ScanSpeak 12W/4524G00	link (Polish site)	A1C1
Mechano323	3	small mid diameter	4kHz		10cm(mid), 16.5cm(woofer)	Dayton AMT2-4	Dayton RS100-4 (mid) Dayton DC160-8 (woofer)	link	None
Mechano24	2	profiled faceplate	3.7kHz		12cm	ScanSpeak D2608/913000	ScanSpeak 12W/4524G00	link	None

* in most cases VXP with off-axis measurements included.


Mechano matrix


CTA comparison on gif (spl levels not calibrated)

 

[RA272]

No replies?

 

[Jim Taylor]

No replies?

I suspect that the success of the Mechano23 ( here and here) has made interest in the Mechano24 a moot point.

Jim

 

[RA272]

It must be. I have the received the crossover components to build the Mechano23, but alas, the drivers are on b/o till Aug.

 

[yogurt21]

How do you, subjectively, find them vs the Mechano23?
I feel like this kind of response in the highs (more volume on-axis, but narrower directivity) would do better in typical settings than the waveguided design - but I'm curious if that's been your experience.

 

[Sicaris]

What leads to the target responses? I see mechano 23 at -0.93 dB/Oct and 24 at -0.71. is there an ideal response, is this determined by the drivers?

Thanks!

 

[XMechanik]

What leads to the target responses? I see mechano 23 at -0.93 dB/Oct and 24 at -0.71. is there an ideal response, is this determined by the drivers?

Thanks!

It's determined by the drivers directivity DI(f). Assuming that system spl characteristic is flat then PR(f)=const-DI(f). The situation is similar with the ER and PIR characteristics.

 

[Sicaris]

It's determined by the drivers directivity DI(f). Assuming that system spl characteristic is flat then PR(f)=const-DI(f). The situation is similar with the ER and PIR characteristics.

Awesome, thank you. It looks like an interesting subject to read up on.

 

[XMechanik]

How do you, subjectively, find them vs the Mechano23?
I feel like this kind of response in the highs (more volume on-axis, but narrower directivity) would do better in typical settings than the waveguided design - but I'm curious if that's been your experience.

Actually, Mechano24 has wider dispersion than Mechano23. This is caused by the integrated horn of H2606 used in M23 (compared to the shallow profiled faceplate of the D2608 in M24) as well as the 15cm woofer (compared to 12cm in M24). For example, M24 has 2 dB lower directivity around 10KHz, which makes PR (also PIR and ER) slope less steep. And this certainly has an impact on the sound, my impression is that M24 are a bit cooler and more analytical. But these are not big differences, both designs have a lot in common.

 

[DearSX]

Asymmetrical driver placement has always seemed visually unappealing to me, but I tried it in my previous (3-way) design and noticed some advantages. So I used this approach again, this time with a 2-way design, and… omg, what an eyesore. What do I to do with it? Maybe a little manipulation of the picture frame, moving the units away from the camera, bringing curves and slopes of the stands to the foreground, a bit of overexposure... ok, here they are.

Mechano24:
View attachment 362777
Enclosure dimensions: HxWxD: 290x174x263mm, polyester fiber filling.

18mm birch plywood, front panel glued "on top".
View attachment 362784

Rear panel flushed into the enclosure.
View attachment 362785

Bass reflex 8l, 45Hz. BR tunnel made of a piece of HDF glued on slats.
View attachment 362780 View attachment 362781

Crossovers assembled on a plywood scrap, attached with screws on an anti-vibration pad to the rear panel (installation through the woofer mounting hole).
View attachment 362782 View attachment 362786

Crossover schematic and the characteristics (rating 6.78/EQ9 6.133/EQ10)
View attachment 362787

THD measurements: ~1.4% peak at 2kHz (87dB/1m)
View attachment 362783

The design is based on ScanSpeak drivers:

• D2608_913000
• 12W4524G00

Hi,

Have you considered doing an off set driver 3-way like the KH310a or ATC SCM 25A, with the woofer to the side for a more compact design? Would that kind of enclosure work with the Mechano323? Or the DCS255 subwoofers?

Reason I ask is cause I wanted to try and put use them in both my (summer) car and home but normal 3-ways are too tall.