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Budget choice is the GRS I used in those 3-ways.
rs225 is lauded as "special" in this WAW build thread.
https://diyaudio.com/community/threads/10f-8424-rs225-8-fast-waw-ref-monitor.273524/
I’ve been happy with the DA RSS210’s. I used 2 8ohms in my push-pull 3-way build (highly damped aperiodic vented), and will be using the 4ohm HO’s in a fully sealed 3 way I’m currently working on. I go with an active (btwn w and mid/coax) and passive for the coax, and this allows for a bit of eq for the woofers- and these have more than enough low-end and Xmax.
In a two-way, the rs225’s may be a better choice? But for a three-way…depends where you want to Xover.
F3 under 50 sealed is tough. I don't think the RS225 is going to do it.
There are still 23 open box Peerless 830667 on sale for $44 each, that might do it.
Not cheap:
Dayton RSS210 subs will
SB Acoustics SB23NBACS45-8 will.
FWIW, the sealed in-room response graphs are shown in the thread....in-room response graphs look to be getting pretty close to 50 Hz.
All good options.
JR, your woofer choice is amazing. The Insomniacs have been my main speakers since I built them and for all-around performance, they will be hard to beat. In retrospect I wish I would have made them look a little better, they deserve better cabinets than I gave them. I do think the woofer is one of the most bland looking driversever made, I might even order a different dust cap to spruce them up a little.
The Peerless 830667 is another great option. I know it is a good sounding woofer, the price is very low for the quality woofer it is.
XRK971's speakers do look like a fun build. I don't have any experience with his speaker designs so other than measurements I don't have any way to gauge them. I'm lucky that many of the people on the forums bring speakers to the events so I can gauge their sound a little, and I can honestly say that there is almost never a dud at the shows. It seems like the recipe for a good-sounding speaker is well understood, quality of drivers seems to be the biggest factor in overall sound quality.
I was working on a sealed 3-way with the 830667. Had to backburner it for a bit to work on some other projects.
https://diy.midwestaudio.club/discussion/2380/peerless-based-8-3-way-build/p1
I built JR's 3-way also as a tower for some friends. Those inspired the above project.
There is also the GRS 8" HE sub that can scratch into the 30s F3 in .5cf sealed with some series resistance from crossover parts. But IDK how feasible it would be to mate to a 3". And it isn't much of a looker.
Your so close you should build that crossover and give it a listen.
Yeah I don't know if I was getting listening fatigue, but my ears weren't being impressed at the time (listening to just one). So I was getting a little frustrated. And I didn't have enough jumpers or physical space to prototype both at the same time. That was the sign to lay off it for a bit and come back some other time more bushy-tailed, and better prepared.
I got more jumpers, and working on the space issue currently.
My vote is for SLS 8” sealed in 3/4 cu ft.
or RS225, but needs EQ to get to 50Hz in a sealed box, IIRC.
The SLS if you only need to cross around 400Hz, the RS225 if you need to go higher to the 3” dome mid.
In some jurisdictions that DSA is cheaper than both and might be more suitable, though I’ve not measured or worked with it.
Having said that I don’t feel that feel that a single 8” sealed woofer is enough to warrant a change over a vented 6.5”
I’d recommend a woofer for a vented 8”, or a 10”…
come on man, don't mess around. PE Ultimax 8 inch
https://www.parts-express.com/Dayton-Audio-UM8-22-8-Ultimax-DVC-Subwoofer-2-Ohms-Per-Coil-295-508?quantity=1
Haven't used or heard but here's one that may work.
https://www.madisoundspeakerstore.com/approx-8-woofers/eton-8-412/c8/32-hex-symphony-ii-8-woofer/
The UM8 does work well sealed and stuffed in about 0.5ft^3. However, you really need the power amp to have enough juice to not clip under operation, and 200W is just there. 300W is better. It is pretty insensitive. The other problem is that Xmax = Xmech in this case. The cone will smack the frame in the rearward direction at xmax. It does make horrible noises when either of these issues approach, so be careful. I would not expect it to do well at higher frequencies.
InDIYana Event Website
The 8" Ultimax is a poorly designed driver simply because of that cone slap issue. Stupid design. Avoid using it.
Is that the case with the whole UM line or more the 8" specifically?
However, is that much of a real concern when used in a small sealed multi-way speaker crossed to a 3"?
The 10" SLS does flat to 2K?
I have a quad of the 8" UM, was looking to go sealed boosted with 2x in 0.5 cf - the cone slap is a concern.... but at 90-100db at 1m looks like even under heavy boosting stays under xmax - but would like to have headroom.
How bad is the 8? and the rest of the ultimax line? I have a 15 which is going into a sub box soon boosted with DSP
It is the only one with this issue. I have the 10 running and love it. The 18 last I knew was the top selling sub at PE.
InDIYana Event Website
I built a sealed box UM15 with 500W plate amp, and it was loafing at volume levels that shook my house.
Hey Wolf - how did you get the spec for Xmech?
Ken, I just thought of another one...HiVi M8N / M8N-b. The new black-cone ones are $39 compared to $51 for the gold-ish ones. I have a pair of the black ones that I haven't opened up yet. If this one interests you let me know, I can burn them in and take real T/S measurements.
Also, the SD215A-88 may work.
@rjj45
No, the SLS 8" is NOT flat to 2KHz. To show the distortion measurement I have to be careful not to overload the mic, so I have to bring it back away from the cone. Moving it to 1m is good, but moving it to 31.6cm is even more useful for a distortion measurement, because I get an additional 10dB SNR (31.6cm is 10dB louder than 1m).
Now, when I show the Distortion graph in REW, it can also show the fundamental. But that's not an accurate as the SPL window, because it shows without gating and a fixed 1/24th octave smoothing. There's no ability to change this in the REW software.
So in the Distortion graph in the earlier post, it does appear flat to 2KHz, due to the smoothing.
A measurement further away requires a longer window to reject the reflections from the room. As you know,
the downside is that the measurement resolution is reduced (1/nth of your time window) when you use a window/gate eg. 5ms window = measurement is limited to a resolution with a 200Hz interval. If you really want to see what's happening under 1KHz, you have to do it a different way.
You either have to measure in the nearfield (eg. 1/2" from the cone) to avoid all the room reflections:
Back to the OP, it depends on the goals of the design. If plan to go passive you're going to have to tradeoff your Hoffman's iron law- small box size vs deep extension vs high sensitivity; pick your 2 desired attributes, you can't have it all.
If you go active you can compensate for differences in driver sensitivities at the pre-gain stage. So you can have smaller box/less sensitive driver and EQ to your liking. But there's no free lunch there either- if you EQ with a 10dB boost, then you loose 10dB of dynamic headroom.
Personally, I find a mild 3-6dB bass boost, or a reduction of required box volume to 1/2 of the equivalent sensible volume for a passive design a good compromise. YMMV.
Of course, there's no replacement for displacement, but also being sensible. One fellow over at DIYAudio blew up his Purifi woofer after trying to play past 11...
My 3rd vote is for a RSS210HF if you’re going active, but this also quite low in sensitivity...
Ooh yeah forgot about the HiVi. Snazy for the price and it should get into the high 40s in .75cf based on factory data.
DC200 comes close to 50hz too.
Check out Michael C. He has done 4 8"/3" variants, one with the Hivi sealed. Hits 51hz F3 sealed... Based on DATS
https://ampslab-spk.com/
What constraints do you have in place for cabinet size and budget?
Just throwing this out there because I can - but if you have $550 (I don't) a pair of these:
https://www.madisoundspeakerstore.com/approx-8-woofers/scanspeak-classic-21w/8555-00-8-woofer/
Will hit upper 40s in 1.0 cubic feet sealed. Using factory parameters, anyways, and 0.5ohm series resistance and all other settings at default this is what WinISD gives us:
Pretty big nut at $550/pr though. That is a lot of banana peels just to hit a sealed bass goal, however.
The SB 8" 4 ohm ceramic woofer does pretty much identical in one cubic foot with a scosche more advertised Xmax:
Costs quite a bit less but still more affordable than the SS classic. Better looking, too.
Couple options there. From a hyper budget perspective the cheap GRS poly sub I mentioned above is excellent, and if high output isn't a design goal the plain old GRS 8" poly cone gets close in a heavily stuffed cube, and costs $10 right now.
And of course if you can find them, a pair of the 8" pulp paper cone Ushers hit just below 40Hz in 1.5 cubes. Incredible bass out of those fellers.