Does a 2 way, 8" woofer - 1 1/8" tweeter speaker make sense? Could it work?

[fjhuerta]

Hi all,

After my experience with my MTMWW, I decided I need a far simpler project to re-learn several things I've apparently forgotten about speaker design, and others I never learned properly, too.

So I decided to start small. A simple TW, 2 way. But I'd like to check on several things, and hear your thoughts about the proposed design.

1) The drivers. I have a pair of 8" SB23NACS45-8 SB woofers.
http://www.loudspeakerdatabase.com/SB/SB23NACS45
https://solen.ca/wp-content/uploads/sb23nacs458.pdf



Probably too big and too directional for a "conventional" two way. But I think it could work if I used this.

Seas DXT tweeeter

Pretty much the only waveguide loaded commercial tweeter I know of. I already used it on my big towers, but one of them was damaged, and I replaced them for a pair of Dayton RS-28s I had.

The thing is, I tested it right up to 1.1 KHz, 8th order, and distortion levels were as controlled as other tweeters running 1.8 KHz, 4th order. So, my plan would be crossing them over at 1.2-1.3 KHz 4th order to the woofer. After testing the tweeters with my big speakers, I'll say that it's possible the SB woofer will run out of extension / power handling before the tweeter starts straining itself (it's only a 60W woofer, anyway).

Do you think this could work? I'm looking for a nice, flat on axis response and smooth off axis response. Which leads me to...



2) The box.

I want to avoid diffraction as much as possible, and help off axis curves. I'm still simulating a traditional rectangular box, a tapered box, a pyramid, and whether the tweeter should be offset from the center. Roundovers, at least 1" are also considered. I've also seen designs where the roundovers are so big, they become part of the stands themselves...

Which shape would you pick as the best one?

[billfitzmaurice]

Eights crossed over to capable tweeters at 2-2.5kHz used to be common. I'd say that tweeter would be fine to 1.5kHz, as would be the woofer. Once you get past a 5th order high pass the returns diminish very fast, so I wouldn't go more than that. As for the woofer, I don't see the need for 25Hz Fs. The mids would be better with a higher Fs/lower Mms driver. If the plan is to have HT capability without a sub the Vd isn't enough to do so at more than modest levels anyway.

[dlr]

Is this going to be with a passive crossover? And 2-way, right?

dlr

[fjhuerta]

Yes! Exactly. Something simple, yet good sounding.

[jhollander]

I think this is a good plan. Al woofer and tweeter are going to make for a highly resolving/ detailed sound. There are also other non wave guide tweeters that come to mind like the Peerless DA32TX Corundum. I'd vote for a rectangular speaker with centered tweeter and big roundover for the simplest design due to diffraction.

[fjhuerta]

Wow. 1.2 KHz crossovers with that tweeter. I'm surprised at it... if there's no real benefit for the waveguide in this project, I'd definitely consider that one. It looks amazing.

[jim85iroc]

I have a soft spot for 8" 2 way designs. I've got 3 different pairs of this configuration from the 80s & 90s. I have a set of Paradigms, a set of PSBs and a set of Missions. The Missions are probably the best sounding set, and surprisingly they use a 3/4" tweeter and a paper woofer. I'm not sure where they cross, but I think it's high enough that there's beaming in the woofer. I kind of like the relaxed midrange that they provide because of it. They don't sound super detailed, but they're generally pretty easy to listen to. They're great with rock music with a nice fletcher-munson type signature.

I've been staring at some different poly & paper coned 8s to build my own 2-way with.

[PWR RYD]

I built an 8" two way a couple years ago with the Peerless 830869 woofer and DA32TX corundum tweeter. People at the Meniscus GTG and DIY Iowa seem to like them a lot.

[fjhuerta]

Another vote for the Corundum.

How did you cross them over?

Also, did you use symmetric slopes?

[Blenton]

Not to hijack the thread but I thought that was with the smaller corundum? I’m sure you would know better than I... Either way, I was thinking of the same project but with the smaller corundum a while back when one of the attendees told me about your project. He spoke very highly of the set.

[PWR RYD]

I used the larger DA32TX in my project. It easily crossed over low and can play plenty loud with low distortion.

[fjhuerta]

I think this is a good plan. Al woofer and tweeter are going to make for a highly resolving/ detailed sound. There are also other non wave guide tweeters that come to mind like the Peerless DA32TX Corundum. I'd vote for a rectangular speaker with centered tweeter and big roundover for the simplest design due to diffraction.

Seriously impressive. And lovely off axis response. Plus, the crossover will be simpler.

Would a waveguide bring any benefits over this tweeter? Other than a slightly bigger faceplate, I can see no drawbacks to it. If not, I'm sold on this one.

[Wolf]

My Zingers also fit this category quite well...
http://techtalk.parts-express.com/fo...8-2-way-design

I still have plans for the DA32 and the TB w8-underhung...

Later,
Wolf

[fjhuerta]

Your post was an inspiration! although my initial intention is to cross over far lower to the woofer.

[tvrgeek]

Depends on the drivers. Used to be SOP for low end, But it usually taxes the tweeter just a bit and finding an 8 that behaves that high may be tough. I think I would look at the better paper cones. Some of the newer tweeters, like the Peerless 1 1/8, might just make it.

All those advertising frequency response graphs don't tell you anything about distortion. It might limit you on max SPL but would be fine at reasonable levels. That is where the tweeter will have issues, down low. Woofers it is the breakup getting that high.

Well worth the effort, but not as easy as a 6/1 might be.

[wogg]

A lot of the designs from InDIYana 2019 would fit the description. I went with an RS180P and the Peerless DX25BG60-4 and it worked out wonderfully.

[fjhuerta]

That Peerless looks nice, too. But the Corundum looks really special.

Unfortunately, it's not available at PE. Well, more time for planning the baffle, etc.

[Blenton]

Don’t discount the DX25. I really like the corundum, but I also really like the projects I’ve used the DX25 in. Note that there are two different versions of the DX25; I believe the one Wogg listed is the beefier version with a backchamber and aluminum faceplate. Both are great but the beefier one is definitely a contender.

Oops - didn’t read lower to see you ordered a pair of DA32’s. Good for you.

[fjhuerta]

The Corundum became available a couple of minutes ago. A pair is on my way.

[rpb]

I think you can make something nice with these drivers! It looks like a steep filter will be needed though, The xo might be a little more complex to push down the woofer output above the xo point. Keep the box large enough to house the xo without a tight fit, but keep the baffle width to a minimum if possible.

[jhollander]

4thtry and I both used tested the the DA25TX below 1,500 Hz with no issues.

[fjhuerta]

If the DA32 can be used at 1,100 Hz, I think this could work.

It's a beast of a tweeter. 1mm of Xmax? That's crazy.

[PWR RYD]

I crossed the DA32 at 1200 Hz no problem.

[andy19191]

Do you think this could work? I'm looking for a nice, flat on axis response and smooth off axis response.

It is a 2 way so performance will be significantly compromised. A budget design using standard range looks a good approach.

If you use subs a 6.5" sealed design perhaps makes most sense. If you don't use subs then there is a case for an 8" driver and a port at the price of port midrange issues and a larger cabinet.

Waveguide on tweeter for directivity control looks wise if one leans towards more neutral sound rather than characteristic sound.

The one thing that looks less wise is the large metal cone. These are almost impossible to use well in 2 ways because when the midwoofer deflects a significant amount (normal for speakers with insufficient cone area) the motor's elevated distortion levels will drive the large high Q resonances creating an unpleasant harsh sound. Note that notches and the like in the crossover will do nothing to prevent this. What will prevent it is a very low crossover frequency with a steep slope which is usually beyond the capabilities of the tweeter. A soft cone without severe high Q resonances is normally a better choice.

Alternatively picking up the challenge of seeing what might be done with an 8" metal midwoofer could be a major theme of the project. After all it is about having fun with DIY.

[fjhuerta]

I'd never heard about what you mention, but I'm looking at the 60ª off axis plot for the SB woofer, and I can see something strange going on from around 1.6-1.8 KHz off axis. A serious dip and a peak.

I'm assuming that crossing over at 1.1 KHz, 4th order, will alleviate this issue. But I don't know whether it will be audible.

Now I'm thinking 6th-8th order filters.

Ah, the joys of DIY :D

[andy19191]

How do I reply to a comment?

Not sure you can ever really win trying to use a hard 8" woofer as a midwoofer. A low crossover frequency will lead the tweeter to sound harsh at high SPLs due to distortion. A high 8th order slope will normally create sound effects due to a high rate of change of directivity. Some may like the effect but it isn't neutral.

I recall Mark K had a go at a 2 way with an RS225 (is there a better link?) and it was considered successful by some. I am more doubtful about a 1" tweeter on a flat baffle crossed 8th order at 1.4 kHz but then perhaps I am just too conservative and boring and listen to music too loud.

[fjhuerta]

I knew someone had already done something similar. But I thought he did them with DXT's. He did one 7" with the SEAS, and the 8" with the RS28. Thanks for the trip down memory lane!