New desktop project using Dynaudio and Seas drivers

[scanspeak]

Hi everyone.

Tired of my old 3" Yamaha desktop speakers I've decided it's time to build some overdue high-end desktop speakers using several nice drivers I had laying around.
Hopefully these will do justice to my recently acquired Topping DX3 PRO and PA5 II.
The Dynaudio drivers are 4" units taken from a Dynaudio Excite X22 centre channel speaker, part# 84022. These drivers have a beautifully transparent sound, perfect for vocals and should be easy to implement.
They are 8 ohm and hence low sensitivity but that's not an issue in this application. I typically listen at about 80-85dB at my desk (1 metre from the speakers) and they'll be combined with my existing DIY subwoofer (driven by a Fosi V3 amp).
The tweeters are Seas T29CF-002 Crescendos which I purchased almost 10 years ago for another project!

SEAS Excel T29CF-002 (E0040) Crescendo Fabric Dome Tweeter

T29CF002 ”CRESCENDO” Ultra High End 29mm soft dome tweeter with HEXADYM magnet system

www.madisoundspeakerstore.com

 

[scanspeak]

A quick sketch of my plans. The front baffle will be angled 10 degrees to match my monitor and time-align the drivers. The tweeter height is at ear level when seated at my desk. Material is 16mm MDF and 2 shelf braces will be used.

 

[scanspeak]

After a few hours of cutting and routing ...

 

[scanspeak]

Driver cutouts are both 110mm. Internal volume about 7 litres.

I like to add hardwood strips along the internal baffle seams.

 

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And after trimming and sanding ....

 

[kemmler3D]

Wow, quick progress! How did you decide on cabinet volume? Are you doing the measure-as-you go style of building or do you have the full plan? What are you doing for a crossover?

 

[scanspeak]

Once I install the drivers I will do the measurements using JustMLS and then design the crossover using LspCAD.
Chosen cabinet volume (sealed) was just guesstimated based on similar drivers. The dimensions were mostly dictated by other factors (listening height, desk-space, time-alignment, aesthetics) and I wanted plenty of internal space for breathing & absorption (and maybe the crossover). The Qtc will be around 0.5 at 100Hz
The bottom end is not really a concern as a subwoofer will be handling that.

 

[jamescarter1982]

really nicely executed so far . I like dynaudio drivers too interesting use of an old center channel I think there's a few older dynaudio speakers about with some quite decent drivers in them

 

[voodooless]

Isn’t this blasphemy given your username? looks nice though, it will probably be a good match for nearfield listening. Just note that you angled the baffle a bit and it’s a 29mm tweeter, so you will have a bit of HF droop from that. May be pleasing or may need a bit of compensation.

What I don’t understand though, is why people keep using MDF to build speakers? Plywood is basically better in almost every aspect, most importantly for your health.

What I find interesting about the design is that they look much bigger than they really are. They look like mini floor standing speakers. Pretty cool.

 

[scanspeak]

@voodooless - Good points that you've raised. Really it came down to what I've always used and what I have easy access to at my local hardware store. Still I might try plywood (or some other material) in my next build to see how it compares.
Is Australian MDF safe?
All MDF made in Australia is now E0 (ultra-low formaldehyde) or E1 (low formaldehyde). These levels of formaldehyde meet the most stringent requirements of the Green Building Council of Australia.

 

[voodooless]

Is Australian MDF safe?
All MDF made in Australia is now E0 (ultra-low formaldehyde) or E1 (low formaldehyde). These levels of formaldehyde meet the most stringent requirements of the Green Building Council of Australia.

Maybe. Even without the formaldehyde, it's all kinds of dusty shit. I used to use MDF in the past as well, but now don't use it anymore in favor of plywood. It's just much nicer to work with.

 

[scanspeak]

Grille magnets installed.

Undercoat

 

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Grilles made from 20 x 5mm hardwood.

 

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Colour is "almost black". I'm using satin enamel but I think I will use a final matt coat to match my monitor.
Internal damping will be 1/2" felt, 1" acoustic batts and sheeps wool.

 

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Ready for measurments

 

[Timcognito]

Ready for measurments

View attachment 329143

I'm avid woodworker and can say, NICE design and finish. Hope the test results are as good

 

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Individual driver responses at 1m (on tweeter axis)

Woofer on and 10deg-off-axis (horizontal)

 

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Individual responses with filters (1st order and notch)

 

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Total measured responses at 1 metre

Note: "Off axis with grill" will be my normal listening setup.
Nearfield measurement of the woofer gave a -3dB point of 100Hz (therefore Q about 0.7).

 

[scanspeak]

Very happy with the final result. In particular transparency, vocals and low-level detail is excellent.
It is mated to my subwoofer (Seas L26ROY) at around 100Hz.