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- johnny5jz 1:44AM
- Tom_S 1:44AM
- tommytunes50 1:44AM
Substand-ards, subwoofer bookshelf stands
I'm finally starting to accept that I need to try and focus more on smaller builds. Looking at some of my future build plans it seems I can pair many of them down to smaller sealed configs, as long as there is a sub to back them up. I have been kicking around the idea for many years of building some bookshelf stands that are also small subs.. Enough that I picked up a couple SA70 plate amps. I think it might be time to indulge that idea...
I was digging around my stockpile and found I have at least four peerless SDS-160F25PR01-08. If the 830855 is a terrier, then the 160F25PR01 is a rottweiler! A ~$25 (I think I got em $20 on sale) 6.5" with 6mm xmax that can dig down to 30hz in 2cf per the factory specs. But with 4x I could put them in isobaric. 1cf seems more reasonable for speaker stand kind of dimensions. Seems kindof crazy to have a 6.5" that needs a 3" port to keep from chuffing before xmax is reached 
.
Sofar I'm thinking dimensions 26" tall x 11" deep. 10-10.5" wide. Isobaric chamber would be some 6" pvc sewage pipe capped with the usual suspect.. menards 3/4" shelf particle board that I have plenty of.
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Those are the drivers I used for my inner sanctum project. I ran them sealed but I am pretty happy with their.
To mount them I have an inner baffle and the drivers are offset. The beston tweeter is almost touching the magnet of the woofer behind it. This left very little extra space between the back of the two drivers.
https://diy.midwestaudio.club/uploads/editor/j1/51vbhdj3x5ca.jpg
That's right I forgot those were Iso. By your description I'm guessing you did magnet to magnet orientation? The frame flange realy isn't condusive to rear mounting.
My thought was to use pvc pipe as if building a mid cup/chamber. If I put the plate amp close enough in-line with the drivers I can use that hole for access. But now that I am thinking out the dimensions of things that might leave less than an inch clearance from the inner woofer to the back of the amp case. I'll need to offset them. Oah well, figuring out the packaging of stuff is probably the most fun to me anyway.
I have a few driver options that could work in this volume.
Peerless 160F25PR01 (Isobaric) - The original idea: They would handle all 70watts just until f3 (~30hz) where they unload. Full tilt puts f0 around 100db
Dayton SD215A-88 (single) - A couple db higher f3 and can only handle 45watts until 6mm excursion becomes an issue, but don't unload until 26ish hz. At the 45watts puts f0 over 102db. Not a bad option as the increased efficiency would give more gain to play with, but always be worrying about crashing the former.
MCM 55-5670 (Isobaric) - They need the enclosure volume to dig deep, but they lose efficiency to do it. They are snoring at half their 8mm xmax with 70watts. If I factor the efficiency loss as the new baseline, the f3 is also around 30hz. f0 output at 70watts is ~99db. But don't unload until ~24hz. If I had 150watt amps to use more xmax this would dominate the others.
DB ratings are from WinISD. Minus baffle step, but plus room gain and the fact there are two playing.. whatever. Atleast they should be comparable.
And by "unload" I mean go past xmax below the port tune at the mentioned wattage.
The 6.5"ers still seem like a contender that would fit well with the project. Then I could save the others for future bad ideas
I picked up a 2ft section of 6" sewer pipe. While at menards I found they carry 3" sewer grade elbows and pipe. It is thinner and less bulky than sch40 stuff. So much so that the flare OD fits inside the flare ID of sch40. But still plenty thick for port duty. Unfortunately they only sell 10ft sections of 3" pipe in that rating... Still debating on maybe trying that instead of the sch40 stuff. This will be my first time using pipe for ports instead of premade ports.
Rough guestimate of the internals. Isobaric chamber out of the 6" pipe up top.
I am more itching to get panels cut for this, but I realy need to sand and finish the LP stand first.. Boo.
From what I remember, the straight tubes from Precision Port aren't as stout as Scd40. You could always wrap them in car sound deadening material.
Decided to go with ABS elbows instead. No need to paint black (yay).
I just figured the thinner sewer grade stuff would be nice when trying to squeeze as much interior volume out of as small an enclosure as possible. It can really add up for multiple long subwoofer ports. I bet it is popular with the car audio guys.
A slot port would be easy with these
Dang you're right!
If I do a 3/4" tall x 9" wide port (10.5" minus .75" sides) WinISD calculates 13.5" length. Subtract the length a bit due to typical lower slot tune... I bet if I do a 3/4" thick panel above the bottom to an internal opening at the back corner (~11" port length) that should tune pretty close. Port velocity seems fine. Aw man, decisions.
So I haven't realy used a sub for many years. Preferring the compromise of pure 2ch.
One thing I have always gone back and forth on with this idea is to hide the driver around back for a more stealth look. But worry I'd lose some bass drum punch from not having it direct firing. Or is that more a mid-bass thing and probably moot for a sub?
Depends where you XO.
I've come to understand that sub-woofers are for HT/LFE and Woofers are sufficient for music/general audio.
Turned the subs off don't miss them for what I listen too . . .
The "punch" should be coming from your mains. Rear facing or forward shouldn't matter for subwoofers, in some cases the rear wall can actually help reinforce the base and absorb some of the higher frequencies that you don't want to hear. We don't see this often in commercial offerings because it doesn't look cool but there are a few companies out there that build them like this for those reasons.
Hense my forte for pure 2ch. However there are builds that could be bookshelf size instead of towers if I make them sealed. As much as it pains me to do that.. I also have to store them when listening to something else. And my storage space is getting to be a premium. Have 2-3 builds in mind already to work with this. Ranging from 60-105hz f6.
I might consider rear firing more then. The idea is to have the bookshelf mains be the center of attention with the subs being monolithic stands that also give the illusion of extended response. Hopefully resulting close enough to tower speaker stereo sound that I won't find it revolting.
I use "stereo" subs as stands and like them. I run them off an I nuke dsp amplifier. I typically start tuning the system with the subwoofer volume all the way down, turn it up until I can barely notice the subs and leave it alone for a while before I fine tune it again. Basically if you are listening to music and you can tell they are on its too loud.
I find sealed bass is way better than most people think. Often the advantage of a ported speaker are almost gone when you factor in 6db of baffle step, sometimes the slower roll off of a sealed speaker can give you more extension.
I sometimes use my dual 12" subs as stands. I find placement is not necessarily ideal, however.
I do the same, this also makes it easy to bump the lowest octaves to switch to more of a home theater response.
Thats a lot of wire
60-105hz f6... f3 would end up around 75-115hz. Hence giving em a little bottom end support.
Nice to see and hear of other's examples.
Several years ago, Scott Wilkinson interviewed Paul Hales, discussing "The Science of the Room" The interview was over an hour long, but if you fast forward to timemark 50:40 and then listen to 1:02:00, there is a very interesting discussion on the directionality of subwoofers in a room. They talk about the "kick drum in the butt" problem that may result from improper placement of subs. Sounds very similar to your comment about losing "bass drum punch from not having it direct firing."
Yeah that was why I was leaning towards front firing. Just weighing if I want bare driver and port (easiest) or put the effort into a design that encorporates a grill to mute the look a bit. Though I don't want a typical boring grill that covers the entire front. That would obviously look like a speaker set on the floor. Maybe go more old school, such as extending the enclosure sides forward to make a frame that surrounds a cloth grill insert. That might contrast nicely to bare driver bookshelf speakers.
Probably using some of the laminate I scored off Egguy on this. IMO a neutral color should go well with any color bookshelf speaker set on top. I think there was some grey oak-like stuff that might work.
Be bold, Go Old . . .
Messing about in MSpaint. The left pair is recessed/framed baffle. The right pair is flat laminate baffle. Outer ones with grill. Topped with a generic 6.5" bookshelf of PE .56cf cabinet dimensions. Much mulling to commence.
Initially I planned 26" height, but went down to 25.5" since that would bring the grill height of the recessed baffle design down to 24". That way I could buy smaller 24" material for the grill instead of buying a large sheet and only using a small portion. Thinking things through.. I may drop down the height even more as long as I don't give up too much internal volume. I'd rather shove something under the speakers if too short than to shove something under my butt if too tall.
A bandpass might be a good option to consider.
I like the look of the left pair of recessed/framed baffles.
Yeah I'm pretty torn. Nothing is off the table yet. Even rear firing. Just exploring the options to get a better idea.
I played around in winISD for bandpass. I haven't messed with those designs enough to quite know what I'm doing. The best I got with 4th order wouldn't dig down quite as low as I'd hope but could be pretty small. And 6th order doesn't seem to save any space. Both seem very touchy with the chamber volumes and tuning.. Probably not a good match for my "estimate it close enough and run with it" design methodology.
Maybe I'll do rear firing and focus the builds to stuff with f3 below 100hz. The one build idea with higher f3 was the PM180. And I can't shake the idea that it is destined for a tower with 55-5670s. Living/storage space be damned!