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Multi-Way Conventional loudspeakers with crossovers

Small Syns
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Old 29th September 2016, 07:53 PM   #181
bwaslo is offline bwaslo  United States
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Default Full Plans for the Cabinet and Crossover, SmallSyns sealed box

OK, for anyone still reading, here are full drawings for the sealed box version, based on 1/2" (12 or 13mm) ply, preferably pre-veneered. Including cutting plans for raw panels (assumed to start out as 48"x24"), and assembly details showing how to align and clamp things. Can you tell that I miss doing engineering drawings since retiring?

No, I haven't built a set with these specific plans yet, but they are close enough to how I did the Shelf-Ported versions and the previous Sealed versions that I'm confident they'll work. But if you spot any errors or omissions, please let me know! Rather than upload the plans here directly, I'm hosting the document on my web site so I can make any corrections or changes there rather than keep posting new 'updated' versions should that happen (like it always seems to).

Here is the link to the overall PDF drawing: SmallSyns Sealed Version Plans

This is what the general plan looks like --
Click the image to open in full size.

An all-in-one-place text writeup/blog is still needed, but for now you can get most of what you need from these links:
I also added some notes and a drawing about how to readjust the "voicing" in the schematic (either sealed or shelf ported version) in case someone wanted to. Of course, if you use the speakers with an equalizer, you could do it there instead, but these can be handy if you want to run the SmallSyns "barefoot". It looks like this:
Click the image to open in full size.

I hope these are helpful.
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Last edited by bwaslo; 29th September 2016 at 08:18 PM.
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Old 29th September 2016, 09:08 PM   #182
bwaslo is offline bwaslo  United States
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Default Next in development?: Version 3, for portable use!!

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Last edited by bwaslo; 29th September 2016 at 09:16 PM.
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Old 30th September 2016, 12:39 AM   #183
SMathews is offline SMathews  United States
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Quote:
Originally Posted by bwaslo View Post

There are a couple of ways to do that. You could use..........
Bill, thank you very much for outlining the waveguide woofer integration process for the "Small Syns" and making the design accessible to a novice like me.

Simmonds
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Old 30th September 2016, 12:53 AM   #184
DPH is offline DPH  United States
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Dunno, Bill, doesn't look co-entrant. :/

(Hahahaha)
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Old 30th September 2016, 12:55 AM   #185
bwaslo is offline bwaslo  United States
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Dunno, Bill, doesn't look co-entrant. :/
Well, it's a variation. Tweeters around the midwoofer instead of the other way around. I particularly like the little propeller at the back.
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Old 30th September 2016, 01:04 AM   #186
DPH is offline DPH  United States
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For those times when you want to take your portable speakers on your boat, of course!
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Old 30th September 2016, 09:52 AM   #187
wesayso is offline wesayso  Netherlands
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Quote:
Originally Posted by bwaslo View Post
Hi Simmonds,

There are a couple of ways to do that. You could use PCD (using the same driver type for "woofer" and "tweeter", at same height, with varying horizontal offsets) and watch the off-axis response vs frequency. Or calculate what the relative delays will be due to different distances from drivers (via Pythagoras, from 8th grade geometry, and the speed of sound) when you are off at at some angle, then put those delays into XSim. You could even use a spreadsheet, calculating the sum of delayed sine waves. In any case, assume the drivers are omnidirectional (which they should be for the most part at lower frequencies, though really, aperture and baffle sizes will still have some effect-- but omni is good enough for approximating). You also have to know about where you want the array to start kicking in, since you want to blend into that from where the waveguide's directivity starts to drop out.

Then, put woofers and waveguide on a baffle and take measurements of waveguide and woofer array at several angles. Finally, design the crossover for flattest falling response at those horizontal angles from the baffle, consistent with what ranges the drivers can cover with decent overall response smoothness and power handling.

I also did the same process at first for vertical off-axis, but it turned out that the trick for that was to get the woofer apertures as close to the waveguide center as possible and then make sure that the phase responses of the woofers and midrange waveguide track each other though the crossover range. Most of the crossover design time was spent getting that phase tracking along with the requirements for horizontal off-axis responses.
Excellent post!
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Old 30th September 2016, 12:22 PM   #188
3ll3d00d is offline 3ll3d00d  United Kingdom
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Thanks for all the details on this build, quite tempted to give it a try. A couple of questions if I may.

I might have missed it but what sort of clean output capability does the (sealed) model have in its passband?

what was the impact of the 12" vs 28" wall distance on the crossover? is it just the loading by the wall or something else?
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Old 30th September 2016, 12:25 PM   #189
sphykik is offline sphykik  United States
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The new plans look great!

Quote:
Originally Posted by bwaslo View Post
(can I assume that there's a great story behind that name?)
It has been my internet handle since I was a young teenager (26 now), but honestly I can't remember how it was chosen!

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Originally Posted by bwaslo View Post
If you are going after cosmetics, look for hardwood pre-veneered ply -- I'm partial to "red oak", but there are usually several types available. Get some iron-on veneer edge tape, too.
Unfortunately my trip on Wednesday did not go as planned. I went to purchase 1/2" baltic birch (what I've used successfully on past projects), but they had sold their birch instead of regular shop grade 1/2" by accident, and didn't have any more in stock. Another place in town has is, but I will have to wait until next week. I was able to pick up some nice 1/4".

Quote:
Originally Posted by bwaslo View Post
The output impedance of the 2x4HD should be ok with about any amplifier or receiver input, it is pretty low. In the living room here, I drive optically from a TV (which is connected to a media center box via HDMI) to the miniDSP 2x4HD, and from the miniDSP right into power amps (I'm using two ICEPower 200ASC modules at the moment).
I use practically the same setup! An old laptop configured as HTPC, HDMI out to the TV, and then optical to a Yamaha receiver. The TV is a crappy Samsung and occasionally drops the signal, but it works.

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Originally Posted by bwaslo View Post
The miniDSP sees the codes and does the actual volume control. You don't really know the volume setting, but you can see that the remote is sending something out at least and what direction it is going. I haven't checked but I think the volume steps are less than 3dB (doesn't sound that course, seems kind of slow, actually).
NICE! I have scoured the miniDSP forums looking use cases. There are a few folks reporting the remote volume issue, but it very well could be the remote model they used. I can deal with not having a visual indicator - maybe I can rig something up.

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Originally Posted by bwaslo View Post
Some people would tell you (and I would have even told you, too, till I actually tried it) that using "digital volume control" into the DAC (which is inside the miniDSP, right before its outputs) will lose resolution when below full volume. But I don't hear resolution being lost even at low volume, I think any loss is down below normal domestic room noise. I think it would depend on gain structure, and if your amp has about the typical gain level of ~26dB, you should probably be fine.
I did an experiment where I reduced the Windows volume to half and cranked up the volume on a Profire2626, versus increasing the Windows to max and lowering the volume on the interface. The latter did seem noticeably better, but I've read so much conflicting information that there certainly doesn't seem to be a consensus. Apparently some algorithms are better than others?

Regardless, I trust your experience and will certainly give that a shot before exploring a passive gain control option.

Thanks again for your assistance!

Damian
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Old 30th September 2016, 06:16 PM   #190
bwaslo is offline bwaslo  United States
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Quote:
Originally Posted by 3ll3d00d View Post
...I might have missed it but what sort of clean output capability does the (sealed) model have in its passband?
Each uses two pro 6" woofers, with xmax of 5.25mm. I've only done this measurement (from post #79), which shows better than decent distortion at up near high listening levels (for a domestic room) --
Click the image to open in full size.
I considered changing woofers to some of the SB Acoustics ones, which have showed some very low distortion figures in others' measurements. But I'm concerned that the actual sound difference might not be much. LF distortion is said to be relatively inaudible, provided it stays in the LF, and the xmax of the SB acoustics woofers is about the same as the FaItal-Pro ones. And it would cause a significant hit on sensitivity.

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Originally Posted by 3ll3d00d View Post
what was the impact of the 12" vs 28" wall distance on the crossover? is it just the loading by the wall or something else?
I ended up skipping the 28"-baffle-from-the-wall effort, at least for now, because I didn't see myself ever using them that way. Moving out from the back wall will reduce the bass reinforcement, which could be easily recovered with EQ if needed (other than several dB loss of possible output capability). And the midbass effects on the crossover design from moving outward got dependent on other furnishings around the speaker -- who has a bare wall with nothing else in the area of their speakers? I may still work up a "out from the wall" design if there's any push for that, but will have to make outside measurements from separate drivers as I don't have a clear range for doing that indoors.
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