3D printed classic 3-way budget speaker project using SB and Dayton drivers

[DanielT]

A tiny update, here is where I am at now:

View attachment 481340View attachment 481342

Center-to-center distance (max. 13.72 cm for the 2500Hz crossover) shall be fine too so I am really happy

View attachment 481346


Next post: midrange cabinet finalization, midrange driver measurements, tweeter-midrange with crossover measurements

Looks nice! That thing with c-c distance. This is what Kimmosto, the creator of VituixCAD, thinks about it. That considering that 1/4 wavelength, which is considered ideal, is practically impossible to achieve in most cases (between mid-tweeter):

Some help with lobing

I think I understand the concept but can't figure out the solution. "Lobing occurs with any two drivers producing the same frequency range in parallel (identical signal) where the distance between the drivers is greater than 1/4 wavelength of any frequency they are reproducing." So if I am...

www.audiosciencereview.com

Your 13.72 cm falls within the range of what Kimmosto considers appropriate and also, if we are to believe Kimmosto, you can increase c-c in your case up to 19 cm. Span between 13.7 cm -19 cm. I don't know if 13.7 cm is better or worse than 19 cm cc but if what Kimmosto says is true, you have some flexibility in working with c-c distance.

 

[Audionaut]

Very few predictions will be accurate because the shape of the housing and the lack of a baffle make any assessments very difficult.

It will boil down to measuring > listening > adjusting > measuring > listening > etc.

 

[ppataki]

This morning all the remaining parts have arrived!

The 4" midrange:

And the 8" woofer:

I don't know about you guys but I find these drivers really beautiful indeed!

Then I managed to finish the midrange cabinet build:

A little knock test before/after applying the vibrodamping sheets:

New video · Thursday, Oct 9

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photos.app.goo.gl

Some photos of the assembled tower (lacking the 8" driver still, of course)

And some videos showing how they sound
On second thought, I have decided to set the crossover to 3000Hz (for now) and did not apply any corrections yet

3 new videos · Thursday, Oct 9

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photos.app.goo.gl

Measurements to follow tomorrow!
So far so good, actually super great! I am extremely happy

 

[ppataki]

Let's see the measurements!
At 1 meter, on-axis, in-room (my home office), 1/12 smoothing

Just to re-cap, the tweeter:

The midrange:

The tweeter and the midrange after pre-EQ:

The combined response using 24dB/octave LR crossover at 2500Hz and time correction applied:

Distortion:

I would appreciate some comments on this, if this counts as fine (remember that the midrange is planned to be crossed to the woofer at 300Hz)

Now let's see the recordings again, but this time with all the corrections applied!

3 new videos · Friday, Oct 10

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photos.app.goo.gl

Both objectively and subjectively speaking I am quite happy with the results but please shout if you have any questions or comments

Next step: print the woofer cabinet and add it to the 'submarine tower' (plus probably a holder/stand will be needed too)

 

[kemmler3D]

On axis looks pretty solid but I'm not sure how much of the ripple below 2khz is real vs. a measurement artifact. Could it be diffraction? That's been in the back of my mind watching this build, there isn't much of a baffle and so nothing to round over either, lots of edges close to the drivers.

 

[Audionaut]

Great @ppataki

 

[ppataki]

how much of the ripple below 2khz is real vs. a measurement artifact. Could it be diffraction?

I have no idea - how could we see that? Shall I measure the midrange from like 1 cm, would that help?

 

[Salt]

You could do some 15, 30, 45 degrees measurements?

 

[ppataki]

You could do some 15, 30, 45 degrees measurements?

Yes, but only in-room, close to the front wall (and somewhat to the corner too)
Would that be of any use?

 

[Salt]

Yes, but only in-room, close to the front wall (and somewhat to the corner too)
Would that be of any use?

That's the way I almost always do it at the beginning
Interpolation (Interpretation) of the results is a bit tricky , but it helps at first glance, esp. when you know what comes from room and what from speaker.

 

[a4eaudio]

I have no idea - how could we see that? Shall I measure the midrange from like 1 cm, would that help?

I'm not sure how you are doing your current measurements... But quasi-anechoic would be to measure from at least 2.5 to 3x the baffle width and then gate the measurements at the first reflection. If you position the speaker such that the woofer is 4 feet high in a room with 8 foot ceilings you will have reflection free measurements down to 300-400Hz and if those ripples are from in-room reflections they will go away.

EDIT: the 2.5-3x baffle width is too ensure you are capturing baffle step effects into your farfield measurements. At 1cm you will have a nearfield measurement that does not reflect the true SPL above something like 400-800Hz.

 

[ppataki]

2.5 to 3x the baffle width

In my case I guess that is 2.5-3x the midrange cylinder's diameter, right?
So 134 * 3 = 402mm, approx. 40 cm

I can do 15, 30 and 45 degree measurements from a distance of 40 cm, gate them at the first reflection and will publish them here (hopefully in the coming days)

 

[Salt]

In my case I guess that is 2.5-3x the midrange cylinder's diameter, right?
So 134 * 3 = 402mm, approx. 40 cm

I can do 15, 30 and 45 degree measurements from a distance of 40 cm, gate them at the first reflection and will publish them here (hopefully in the coming days)

A good start

 

[kemmler3D]

In my case I guess that is 2.5-3x the midrange cylinder's diameter, right?
So 134 * 3 = 402mm, approx. 40 cm

I can do 15, 30 and 45 degree measurements from a distance of 40 cm, gate them at the first reflection and will publish them here (hopefully in the coming days)

Sounds like a plan. Will be interested to see what happens with the mid-range...

 

[ppataki]

OK guys here you go
Again, in-room, close to the front wall and to the corner - no filters applied apart from crossover and time correction

The first reflection is at 0.137 ms

Gating with that gave me this:

I guess this is not what we need, right?

Gating with 3ms (to go down to 300Hz) gave me this:

Please comment on what settings I shall use, happy to play with the measurement (attached also)
Thank you

 

[ppataki]

Using the 3ms gated version of the measurement I used VituixCAD to create a polar map about the directivity
(not sure if it makes any sense to do it with those measurements but anyway...)

 

[a4eaudio]

Please comment on what settings I shall use, happy to play with the measurement (attached also)
Thank you

I think your 3ms gate looks fine. You might be able to go even a little higher but not sure there is much to be gained for now. The key is that without gating you have a LOT of ripples between 300Hz and 2000Hz but that is all room reflections and have disappeared with the gated measurements.

 

[ppataki]

I think your 3ms gate looks fine. You might be able to go even a little higher but not sure there is much to be gained for now. The key is that without gating you have a LOT of ripples between 300Hz and 2000Hz but that is all room reflections and have disappeared with the gated measurements.

I am very happy to hear that! Thank you for confirming
Actually when I was designing this cylinder ('submarine') speaker concept, I was having a lot of discussions with Claude (Opus 4.1) and I specifically asked him about the diffraction and he told me that it should not be a problem - thankfully he was right

What I am not sure about is that directivity error around 6kHz (slightly visible on the polar map) - is that the driver or the cabinet or...? Is there way to tell that somehow?

 

[Salt]

Measure speaker in some other place or with different distance to the walls and compare.

 

[ppataki]

Measure speaker in some other place or with different distance to the walls and compare.

Yes, that is the plan once the woofer is also in place (in 10 days max, hopefully)
Next post will be about the woofer's cylinder