Project M2 DIY Thread

[4313B]

I hit a hard wall, should of bought my D2 drivers when they were available.

I received my three very recently. Ordered them last April, waited the obligatory year for delivery.

All my parts are still in boxes.

Mine too.

I am actually looking forward to building some boxes this summer.

[johanwholst]

I just finished cutting all the pieces for the cabinet. Remains to order ports, gasket tape, threaded inserts etc... but 2216nd and D2 are up and playing in a recycled cabinet

Hope to finish the boxes before mid june

[johanwholst]

How do you M2 diy guys route out for the 2216? Is the rubber lip on the 2216nd sunk into the baffle plate resting on a sunken edge or do you leave it on top of the front baffle?

[dprice]

I sized the opening on the front front baffle such that the rubber lip is on top of the front baffle and covers the slight gap between the frame and the baffle.

[johanwholst]

I have only seen the original once, but isn't the rubber sunk into the front baffle? doesn't really matter as long as the rubber seals a gap...

Then you sink the woofer approx 1/2" ?

[pos]

Is the rubber lip on the 2216nd sunk into the baffle plate resting on a sunken edge

That is how it is done on the original:


According to Stéphane the additional baffle is around 15mm, so the edge must be 2 or 3mm deep.

[johanwholst]

Great pos. Thanks for the confirmation.
This was my plan. 16mm plate on top of the 25mm. sink edge at 13mm for the rubber lip

[dprice]

I sized the opening on the front front baffle such that the rubber lip is on top of the front baffle and covers the slight gap between the frame and the baffle.

I should have clarified that I used ~12mm plywood on the front baffle so no need to cut a recess for the lip.

[johanwholst]

that's a good way. I had plenty of 16mm mdf, so I will route it down for the lip.
Not decided with the ports yet if I should just route the flare or use a plastic flared front or end piece. Looks kind of cheap and plasticky...
Got 5mm threaded inserts (Rampa) for the woofer mount, and 4 pole speak on for the connection in the mail now.
Next decision would be if I should ditch the network, use only the capacitor, or go for the whole thing Witt attenuating resistors.. Guess I have to decide on amps firsts
Any opinions if the resistors actually influence the EQ curve other than the attenuation?

[Mr. Widget]

I have only seen the original once, but isn't the rubber sunk into the front baffle? doesn't really matter as long as the rubber seals a gap...

Then you sink the woofer approx 1/2" ?

If you really want M2 performance, every detail matters:

Early in the M2's development the portion of the baffle where the 2216nd mounted was flat all the way to the bottom of the baffle panel (the waveguide was always proud of the woofer baffle). After uncovering the response anomalies and determining their cause, Devantier re-designed the woofer baffle with the lower baffle area proud of the woofer mounting area, which eliminated the anomalies. I know this because after seeing the initial prototypes with the flush baffle, Alan showed me a later version with the step. I asked him why he added it, since to my mind the step would cause diffraction, and he explained that the stepped baffle actually eliminated response anomalies in the 500Hz region without causing any audible or measurable diffraction effects. (Which in hindsight makes sense, since the wavelengths at the top of the 2216nd's operating range in the M2 are around a foot long, too large to be affected by the baffle step.)

So if it's a true M2 clone you're after, you need to include this stepped baffle—it's there for performance reasons.

Widget

[pos]

Next decision would be if I should ditch the network, use only the capacitor, or go for the whole thing Witt attenuating resistors.. Guess I have to decide on amps firsts
Any opinions if the resistors actually influence the EQ curve other than the attenuation?

Oh yes it does, by attenuating the impedance peak.
If you remove the lpad bu keep the 1kHz cap, the resulting response curve will have a peak corresponding to the impedance peak.

If you want to remove the lpad in order to be able to use a low power amp, then you should only use a protection cap.

I made a few measurements comparing the original (cloned) network and a simple protection 30uF cap.
I can publish the required EQ to compensate for the difference.
What DSP unti are you using?

[pos]

Thank you for posting this here Widget, I missed it!
http://www.audioheritage.org/vbullet...024#post390024

[johanwholst]

Thanks widget.

POS: I am using Hypex DLCP for now, but struggle with too few PEQ's. I have Minidsp 2x4hd inbound for the pure fun of testing it, and wait paiciently for the perfect pre/dsp solution to come in hopefully near future. Maybe Hypex oem two by four (Isis ) could be it? We will see in Q4 I believe.

Please share your comparisons. Both me and a Norwegian DIY friend using Hypex experience the area 7-10k hz quite hot with your EQ, and I need to notch this area down approx 3-4dB with a wide Q.

[johanwholst]

Just to clarify mr Widget; with the stepped baffle, hsosdrum refers to the protruded lower 1/3 of the front? In other words, the port section protruded?

[pos]

Thanks widget.

POS: I am using Hypex DLCP for now, but struggle with too few PEQ's. I have Minidsp 2x4hd inbound for the pure fun of testing it, and wait paiciently for the perfect pre/dsp solution to come in hopefully near future. Maybe Hypex oem two by four (Isis ) could be it? We will see in Q4 I believe.

Right now using one openDRC per side is the easiest way I found.
I have high hopes on Tranquility bass' system, but it takes time for such a product to make it to the market..

Please share your comparisons. Both me and a Norwegian DIY friend using Hypex experience the area 7-10k hz quite hot with your EQ, and I need to notch this area down approx 3-4dB with a wide Q.

This is not my EQ, but a straight copy of the one found in the Crown DSP/amp.
Many on-axis measurements of the original M2 show this phenomenon.
eg:
http://www.audioheritage.org/vbullet...l=1#post380146
http://www.audioheritage.org/vbullet...l=1#post360555

I did not have the chance to do extensive measurements myself yet.