Recommend a 2 or 3 way project for 80hz and up

After making full range floor standers and a pair of subs I want my next project to be a 2 or 3 way. I’m trying to get to a higher degree of realism at higher SPLs than 6” full range can do. I only need low end above 80hz (or maybe as high as 100) so I’d like to maintain a modest efficiency (say, above 90db/W) without a huge box. Listening distance is typically 8-10ft when on the couch, the room is 16x32’ with cathedral ceilings.

I’ve been looking a at a couple of Troel’s Designs, specifically the Quattro MKII and the SBA 16 MTM. At my most adventurous his Faital 3 way seems doable but frankly is a bit bigger than I’d like right now. I love the look of big speakers but I’m short on tools and workshop space to manage big cuts and parts.

So I’ve been poking around the web for weeks and I’m hoping a little input from the forum will help me find any other options that fit and ultimately pick something to work on soon.

Thanks
 

jReave

Member
2012-10-30 4:34 pm
Pretty hard to argue about the quality of the SBA 16 MTM.

Do it sealed instead of ported to reduce the cabinet size. About 10 to 13L per driver depending on stuffing should do the trick. F3 in the neighborhood of 62Hz.

Maybe double check with Troels just to be sure. His measured TS parameters are a bit different than SB's.
 
[QUOT subwoofers
E=BJosephs;6112170]I want my next project to be a 2 or 3 way. I’m trying to get to a higher degree of realism at higher SPLs than 6” full range can do. Thanks[/QUOTE]

An EconoWave with a 12" midbass and the 15" SEOS waveguide would be a good high efficiency speaker with controlled directivity. There are a few good 12" midbass with -F3 ~80Hz in a sealed 1.5cuft cabinet.... or -F3 ~50Hz in a ported 2.2cuft cabinet.

Pick a cabinet width which fits your room, and diyAudio members will suggest 8", 10", and 12" midbass EconoWave designs.
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Pretty hard to argue about the quality of the SBA 16 MTM.

I've seen some criticisms regarding directivity. Specifically that since an MTM has intentionally limited vertical dispersion you need to to have the tweeter at ear height. In another thread someone who made them said they weren't for filling the room and moving around while you do chores, they were best for sitting in the sweet spot. I hadn't considered it when I originally posted this thread but given my room size and listening habits I think this sounds undesirable to me. It's hard to know without building them but that's the only negative I could find.
 

jReave

Member
2012-10-30 4:34 pm
Just about any speaker should have the tweeter at ear height, not just MTM's.

In terms of room filling, if you are talking about SPL's, again not a problem for the MTM's. Especially if you are only running them down to about 80Hz.

But if it's about maintaining the same FR anywhere in the room then, again, just about any speaker falls down in this regard except for omni-directionals and maybe line arrays. I'll bet that your current speakers' off-axis performance both vertically and horizontally lacks the high frequencies they have on-axis, and yet I'll wager you don't really notice too much of a difference when you stand up or walk around the room.

For me, the perception of these changes really marks the difference between an average listener and an audiophile (audiofool?). I lived for years and years perfectly happy listening to music while walking about the room or even in another room all together. It wasn't until I started studying and building speakers that the differences became apparent to me. And still I don't really care too much. For serious listening, I sit down on-axis and at ear height to the tweeter. For the rest of the time, I don't listen critically and so I'm still perfectly happy with what I hear. YMMV of course.
 
That's totally reasonable. My current drivers also beam and have a falling off-axis response in the treble. They are a little sharp as it is so I leave them facing straight forward rather than toed in to accommodate.

If what you're saying is that an MTM won't be noticeably worse in this attribute than any other archetype then I won't weigh it too heavily in my decision. Thanks.
 
Here's a 3-way that you can put in a denovo box that covers 80 Hz and up, and has 90 dB sensitivity. You would need to build the inner cabinet for the mids, but it doesn't have to be cut nicely since it's not visible from the outside. It does have a limited vertical dispersion, but measures well within 15 degrees of the tweeter height. That's about +/- 2.5 feet at 10 feet away. If the tweeter height is 40 inches, that gets you from 10 inches off the ground to just shy of 6 feet off the ground. Horizontally, the response is very wide, with 45 and 90 degree off axis plots supplied at the link.

Skylark Flying Towers: Nested Array Speakers in Denovo Cabinet -

Techtalk Speaker Building, Audio, Video Discussion Forum
 
Do it sealed instead of ported to reduce the cabinet size. About 10 to 13L per driver depending on stuffing should do the trick. F3 in the neighborhood of 62Hz.

A sealed enclosure of of 8.5"W X 24"H X 12"D with 18mm plywood works out to about 28 liter gross. If I build the SBA 16 MTM (Which is really the front runner right now) then this is probably what I'll do. I want to double check tweeter height when stacked on my subs... though I can build a plinth to house the crossover of an arbitrary height to get the tweeter up high enough.
 

adason

Member
Paid Member
2004-11-10 8:31 pm
Maryland
After making full range floor standers and a pair of subs I want my next project to be a 2 or 3 way. I’m trying to get to a higher degree of realism at higher SPLs than 6” full range can do. I only need low end above 80hz (or maybe as high as 100) so I’d like to maintain a modest efficiency (say, above 90db/W) without a huge box. Listening distance is typically 8-10ft when on the couch, the room is 16x32’ with cathedral ceilings.

I’ve been looking a at a couple of Troel’s Designs, specifically the Quattro MKII and the SBA 16 MTM. At my most adventurous his Faital 3 way seems doable but frankly is a bit bigger than I’d like right now. I love the look of big speakers but I’m short on tools and workshop space to manage big cuts and parts.

So I’ve been poking around the web for weeks and I’m hoping a little input from the forum will help me find any other options that fit and ultimately pick something to work on soon.

Thanks

betsy wow and ribbon
 

jReave

Member
2012-10-30 4:34 pm
A sealed enclosure of of 8.5"W X 24"H X 12"D with 18mm plywood works out to about 28 liter gross. If I build the SBA 16 MTM (Which is really the front runner right now) then this is probably what I'll do. I want to double check tweeter height when stacked on my subs... though I can build a plinth to house the crossover of an arbitrary height to get the tweeter up high enough.

Sounds good to me.

I would chamfer or roundover your edges, brace the cabinet well (horizontal window braces every 4" to 5" and 1 vertical brace down the center or just off-center if you want to be picky), damp all internal walls and use an aggressive insulation strategy with a progression of densities while still leaving room behind each woofer to breathe. Personally, I like to oversize my sealed boxes to accommodate that later strategy if I can. Depends on size constraints though. But especially with high quality drivers, I want to really kill back wave reflections and seriously attenuate any cabinet wall/front baffle SPL transmission as well as resonances.

Also because with a 2nd order HP rolloff at 80Hz to accommodate your sub, the woofers will only be limited by their power limits not their excursion limits. Max SPL at 1m with 60W will be in the neighborhood of 110dB. :tilt:
 
Before I pull the trigger on parts I wanted to ask once more about what people thought I’d the different tiers available from Jantzen:

http://www.jantzen-audio.com/wp-content/uploads/2018/04/SBA-16-MTM-All-kit-versions-with-prices.pdf

It looks like the only difference between a level 1 and “ultimate” is a single upgraded capacitor. I want to do beryllium so I’m thinking I’ll spring for the level 1. I’m honestly a bit skeptical that I’ll hear what a few hundred dollars does here but since I’m importing the kit I’d like to just make sure I build these once. I could buy the drivers domestically but they actually look a bit cheaper when rolled into the kits - though after shipping and tariffs it may be a wash.

Thanks,
Brian
 

giralfino

Member
2009-02-28 9:20 pm
I could buy the drivers domestically but they actually look a bit cheaper when rolled into the kits - though after shipping and tariffs it may be a wash.
You have to quote price for parts + shipment cost, as since drivers are heavy, the shipment from DK to US could cost much more for the kit with drivers than without them.

As to the different crossover options, I'd opt for a Level 3 that unfortunately doesn't exist... I think that wax coils are a PITA to solder so I'd like to have equivalent air core coils (same inductance and near enough DCR), and Superior Z or Silver Z are IMHO the max I'd like to spend (*). Maybe ask Jantzen for a special price on this custom package.

Ralf

(*) Why buy overpriced 100-200VDC +-3/+-5% caps, when you can buy excellent 800VDC +-2% caps?
 

jReave

Member
2012-10-30 4:34 pm
Yea, if you buy the soft dome and no matter how much you like it, a year or two or three down the road you will still be wondering how much better the beryllium would be. Especially if you can afford it.

I write this slightly tongue-in-cheek (but not really....). ;)
 
You have to quote price for parts + shipment cost, as since drivers are heavy, the shipment from DK to US could cost much more for the kit with drivers than without them.

I keep rerunning the math and, for whatever reason, it seems that the Jantzen kit price plus shipping is almost exactly the price of buying just the drivers from Madisound. Even with a potential tariff of 5-10% its seems like there’s no waste to ordering them all as a kit.
 
OK, I've told Jantzen to send info on how to pay with wire transfer so now I'm sketching up my box plans.

As discussed, I'm going to build them in a smaller sealed box that targets a QTC of .7 and a -3db point just above 60hz. Attached is a draft of a modestly braced cabinet with a net volume of 32l before accounting for the drivers and crossover. I figure anything I lose in volume from those components will be compensated for by the fluff.

The width will be the same as Troel's but the depth was increased a little bit. Height is reduced to 28" so that the tweeter will be roughly ear height (while sitting) when stacked on top of my 15" tall subs. The lower part of the back will be removable for crossover access which is why the hidden lines in the lower back show material in the corners, something to screw the panel to. This is also why the lower brace doesn't go all the way to the back of the box.

Material is Baltic Birch plywood. Construction is typically wood glue and biscuits.

Thoughts?
Brian
 

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jReave

Member
2012-10-30 4:34 pm
At a minimum I would use 4 horizontal braces plus 1 vertically. As it stands your top and bottom panels are unbraced and so is your back removable panel. And your side panels have what look like about 8" x 10.5" sections that are unbraced.

For that back panel, continue your braces right to the back and then screw the panel right into the braces. I often prefer to use metal/machine screws and threaded inserts for removable panels instead of wood screws. Glue on extra small pieces of wood to the braces where/if necessary to ensure the inserts are strongly secured.

The thing with a 2-way is that it's rather difficult to push each panel's resonant frequency either above or below the mid/woofer's passband. So the best strategy is to push it as high as you can where there is less and less energy there to excite them. A 5" x 11" section of panel for example has a significantly higher resonant frequency than an 8" x 11" section. 4" x 11" is higher still and with Baltic Birch may actually be getting up close to the SBA-16's xo frequency. It's helpful too to vary the panel sizes a little bit so that there are as few unbraced sections of panels that have the exact same resonance frequency ringing all at the same time. Now if a panel does happen to start resonating, it also helps if it's damped too. Damping though adds mass without an increase in stiffness so unfortunately that drops a panel's resonant frequency. Another reason to push those resonant frequencies up as high as you can to start off with.

Let me say as well though that this topic is rife with personal opinions so others may use a different strategy. Perhaps sift through them and decide what you think is the best for you.