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Sugar Cubes
My wife named them, so when you see her this October remember to compliment her.
Drivers are the Dynavox 5" poly cone and the SB small form factor ring radiator. SB29RDCLMNOP123 or something like that. I barely remember my wifes phone number so don't ask me to reel those model numbers off.
A 1" round-over on the cabinets. I duratexed the port tubes, I like how it turned out.
Cabinets are done, just gotta cure the Duratex for awhile so it doesn't cement the drivers in place. Next week sometime they should be alright to load with the drivers and start the measurement process. I'll hit the driver openings with a heat gun yet today to accelerate the process. It is sandable and odorless well before it is fully cured.
Cabinets are net 0.4 cubes tuned to 53Hz. F3/6/10 of 47/42.5/38. Should be real nice in a smaller room. See how they do in a larger space like Ankeny. If I get the crossover right, they would probably make an excellent nearfield playback monitor and I may shop it at a local studio. I have sold several pairs to musicians through there.
The 1db scale in WinISD makes it look fatter on the bottom end than it will sound. I modeled with 0.4 ohms of series resistance.
Here are the drivers temporarily in place. Should pop when it is all buttoned up.
and 2 others.
Comments
I think you will find that woofer is very easy to use. All I needed to do was notch it and it rolled off by itself. Good luck. I think you'll enjoy it.
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nice !
what's the id of the port you are using, and what's the targeted length ? thx
2"x6" and change.
Sweet!
Looks like a nice combo, JR!
Looking forward to seeing/hearing them! Kudos on the post tags.
Those tags bring back some memories lol
Yeah, as the recipient of some pretty awesome tag assaults I remember laughing my ass off more than once.
Nothing better to do but spend five-six hours playing with alligator clips and crossover components and my poor ears.
This is very nice. That SB is a Beast Mode(©) little fella. 1600, doesn't break a sweat. Notched hell out of it at resonance. This is not a cheap crossover.
Looks great!
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I look forward to hearing these in Iowa. I don't think I've ever heard either of those drivers before. Nice work JR!
Here are the drivers raw responses in-box:
The tweeter response surprised me. Even considering the 1" round-over and driver position on the baffle that is pretty damn smooth. Made it easy to work with once I tanked the impedance peak. Very easy to work with, as a matter of fact. I am pretty sure I am pushing it just to it's limit at 1600Hz but it does it - but it can cross anywhere with minimal effort.
So this is what I ended up with for overall response:
This is the crossover. The only thing out of the really typical 4th LR type of thing is the notch on the tweeter. It is necessary to cross it as low as I did.
As noted above, this is not a cheap crossover - especially if one were to use a poly cap in the notch. I happened to have a couple 50uF 100V poly caps sitting around that I used, but that voltage is not exactly a common commodity at typical DIY stores. In fact, this isn't a cheap build at all. It costs about $200/side +cabinets/finish and accessories like binding posts, crossover boards, the handful of poly-fill it requires right behind the woofer, etc - and that is using all Dayton Audio crossover components. Stepping up to a better cap would easily launch the pair in to the $500 territory. While I would of course be flattered if someone were to build these, I would not personally recommend them as the value to performance is somewhat lower than a typical 2-way bookshelf speaker. The woofers are now $130/pr and the tweeters are $143/pr. That tweeter cost is really what drives the value down - you really **have **to have a small form factor tweeter that will play low to justify it. I just happened to be tired of looking at them on the shelf. Don't get me wrong, they are pretty damn nice tweeters, (and the speakers turned out pretty damn nice imho) but so is the $35 Beast Mode(©) at half the price. That small faceplate is the cost/benefit analysis the SB fails on. Just my humble opinion about my own design and how I decide to recommend a design or not.
The woofer, not so easy to work with. I found playing it above 2K to be unsatisfying. I started the project crossing at 3K and worked down from there. The sweet spot I found was between 1600 and 1800, I drifted towards 1600 because that is where I found the best reverse null. That isn't everything in overall speaker design - but it is when working with 4th LR designs. I did take off-axis measurements as part of the design kick-off and a few after the fact and it behave exactly like a 4th LR does. At this time, I have built enough designs using that topology that it is easy to predict off-axis performance. It doesn't vary much outside of what the edge treatment on the baffle influences. The larger the roundover, the small the "bloom". Crossing as low as I did reduces that bloom as well. Long story short, these do not do as bad off-axis as a typical ~6-7" CTC 2-way 4th LR crossing higher than I did at 5-1/2".
All in all, I would say the poly cone on the Dynavox outperforms their honeycomb cone at least 3 if not 6 ways from Tuesday. A much better sounding driver. I did some A/B yesterday (not scientific at all mind you) against that Dynavox design I did earlier this year (with the Seas tweeter in a waveguide). Those are nice, but the Sugar Cubes are just better. I may buy a pair of the poly 6" Dynavox and re-work that design.
Anyways - I enjoyed this build and plan on leaving it in permanent rotation downstairs. Sigh... I have too many speakers...
I have my reference pair in my nerdery (Motus + Viawave), I have that Dynavox/Seas build in the utility room where I workout and build/assemble my speakers, I have the Taiga (my other reference) upstairs in the living room, I have a pair in the garage, I have a pair in our home office, a pair in our little home bar, and... six pairs in our downstairs living room. Plus the twin subs downstairs, and one in the home office.
Some of you probably have more, I'd like to hear who does so I can tell the wife I don't have a problem. She is the best DIY'ers wife ever but even she might be losing patience with my hobby encroaching on the entire house. The only spaces without a TV/Audio or PC/Audio setup is the master bedroom, kitchen, and bathrooms. I don't have plans to install anywhere in those spaces, either.
I love those old Realistic Soft Dome Mid's . . . damn sweet sounding . . .
There may be a bit of rose colored glasses going on there. It was the most difficult dome driver Ive ever worked with. I hammered it into shape, though and it sounds pretty solid. The Minimus tweeter was the real surprise in the speaker, though. Well, the old poly cone woofer is also very, very nice. Always surprises people when that 40 year old design sounds like it does.
Craig, the Dyn5 was used in Nick's Moon Drops, my Vijon.
Nice build, JR! Nick and I both found the response lent well to LR6 at about 3k without too much trouble. Yours looks great!
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The price increase on the Dynavox woofers is truly a shame, because at $45, they are a great driver.
JR - I have a pair of these tweeters on the shelf that I plan on building by InDIYana 2023 (not the theme). You mentioned you started all the way up at 3Khz. Do you remember if there was a point (and where) you didn't need the notch?
Probably noticed the honk at about 2500.
The SB29RDNC was used in Zaph's design contest way back in 2010. You can review several different designs HERE. First place overall was an LR4 (acoustic) @ 1.6 KHz by Francisco Javier Huerta. He didn't use a notch, but used an L-pad that created > 10 dB attenuation. I used a variation Francisco's design and it sounded great. YMMV.
I thought Dan Neubecker won that contest. Or at least tied it.
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Well whaddya know, arrival at same gate from different planes.
Dan won the 3-way, Francisco was the overall 2-way winner (there were multiple 2-way categories). IIRC the 3-way designs were based on simulations only, but the 2-way designs were built and tested.
Okay, didn't know there was more than one category, or at at least did not recall.
Thanks.
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Thanks for sharing JR. I appreciate everyone here for sharing in fact.
For anyone that does want to make these, the woofers are cheaper over at MCM at $42/each:
https://www.newark.com/dynavox/lw5004pmr-nm01/5-25-pp-mica-woofer-80-watt-6/dp/78Y7663
My guess is Newark will price their next import batch similar to PE, or possible even stop carrying them. But yes, right now they are a helluva price at Newark.