The Boomsticks: 2.5-way high WAF w/ 4xRS100-8 and ND25FA tower

[Navy Guy]

"Yeah. All right, you primitive screwheads, listen up. See this? This...is my BOOMSTICK! It's a 4" quad woofer tower, S-Mart's top-of-the-line. You can find this in the electronics department. That's right, this sweet baby was made in Ann Arbor, Michigan. Retails for about $299.95. It's got a MDF stock, brushed aluminum and a hair trigger. That's right. Shop Smart. Shop S-Mart. YA GOT THAT!?"

I've got a lot more info on these over on the PE board or my blog, but I don't have time right now to post it all. Will try to later tonight or tomorrow but here is the current status

[Alaric]

You get so many bonus points for Army of Darkness references. LOL :T

[Navy Guy]

The Boomsticks: 2.5-way high WAF w/ 4xRS100-8 and ND25FA tower



It is a slim-line, high-WAF tower using four Dayton RS100-8 woofers and one Dayton ND25 tweeter per side. The f3 should be in the upper 40s with f10 around 40 Hz and can take about 30-40 watts above tuning without exceeding x-max and good cone control below x-max for a ported design. Overall, it will have about the same cone area as a 6.5" woofer, but the cabinet is only 5.5" wide.



20 watts input power

[Navy Guy]

The Boomsticks: 2.5-way high WAF w/ 4xRS100-8 and ND25FA tower

I had the cabinets cut by a friend with access to a CNC machine. He came up with a great idea to help line up the mitered corners on all the panels which you can see in the first two pictures. This eliminates the lines you might get that would eventually telegraph through a painted finish.

Cabinets have been completely assembled and lined with Flex Seal. I wanted to experiment with it as a damping compound. I wouldn't recommend using this, and I definitely won't ever again. Not only is it expensive, it is difficult to get a thick coat and it doesn't really seam to deaden anything much. There are probably better alternatives that are cheaper or similarly priced.

The last picture is trying to give you a perspective of the size of these cabinets. They are very thin little towers.







I decided to try Dupli-Color Metalcast paint for this project. After priming and sanding for paint (lots of sanding), I sprayed the Metalcast base coat. As you can see from the pictures, I had problems getting it to coat with an even color. I kept getting light spots in some areas and dark spots in others. The whole thing feels smooth and when viewed up close you can't see this, so I'm not sure what is causing it. I'm hoping that the color coats will cover it. After checking a couple test pieces, I decided to go with red laid down first followed by a coat of orange.

[JonMarsh]

Well, it certainly looks like you're having fun building these! And they're coming together pretty quickly...

My own take is that painting is harder than it looks at first, watching someone else do it... good luck with that! :T

[Navy Guy]

Well, it certainly looks like you're having fun building these! And they're coming together pretty quickly...

My own take is that painting is harder than it looks at first, watching someone else do it... good luck with that! :T

Not really that quickly. I've been working on them since New Years weekend. But we didn't get authorized by PE to post on our projects until around the third week of January, so I had a lot to post at once.

I agree on the paint. Done it quite a few times now and still have issues even though some make it look super easy.

[Alaric]

Beautiful speakers.

[TEK]

Looking good. Really like the mitered look on the baffel. And it seems like you're done a great job getting the edges even.
Did you do any pre-treatment before putting the dupli-color base coat on, or did you do that directly on the MDF?
Strange about the different areas of shine - no idea what that might be caused by. As it is only the base coat - hopefully it won't be a problem with the final finish.

[Navy Guy]

Looking good. Really like the mitered look on the baffel. And it seems like you're done a great job getting the edges even.
Did you do any pre-treatment before putting the dupli-color base coat on, or did you do that directly on the MDF?
Strange about the different areas of shine - no idea what that might be caused by. As it is only the base coat - hopefully it won't be a problem with the final finish.

I used a Zinser BIN to seal everything and then filled primer over that to get an ice even prepped surface. I've got a coat of clear on now and there is some blotchiness. It's. dryer than before but still visible in the right light. Not sure why it's so hard to get an even coat. I read that other people have had this issue with the Metalcast so it might just be part of the problem of using it on a large non-metal surface.

[Navy Guy]

Finished putting drivers into one of the cabs and the base on today. Hoping to measure this week.

[wkhanna]

looks good from here :T

[Steve Manning]

Very nice ...... I'm liking the red.

[cochinada]

I like the red. Aren't you a bit worried these might topple due to being so high and narrow? I sure hope you don't have cats in the house. :W

[---k---]

I think you could have fit 2 to 4 more RS100 in that height.

[Navy Guy]

I like the red. Aren't you a bit worried these might topple due to being so high and narrow? I sure hope you don't have cats in the house. :W

No cats, so not much worry there. Without the base, they didn't feel stable at all. The bass helps a lot, but I might still add some spikes on the the bottom of them to dig into the carpet a bit better and give me the ability to level adjust to some degree.

I think you could have fit 2 to 4 more RS100 in that height.

Definitely could have (and considered it) but I would have had to make the cabinet quite a bit deeper to keep low frequency extension the same.

[wkhanna]

are these ported?

[Navy Guy]

are these ported?

Yes. Two 2" ports tuned to around 53 Hz. A single 2" with a flare should work ok, but the PE precision port wouldn't fit easily on the cabinet.

[wkhanna]

thanks for the answer.....

my bad......i see now in post#3 where it is covered.

[5th element]

I'm liking these a lot. I really enjoy the aesthetic of multiple small drivers.

[Navy Guy]

I'm liking these a lot. I really enjoy the aesthetic of multiple small drivers.

Thanks. I'm excited to get some measurements and a crossover together to see how they sound.

[Navy Guy]

I had some time today to get things measured and play around with a crossover. I had all the parts on hand to build it so threw it together pretty quickly. Overall, a very simple crossover. Second order electrical with a bottomless notch on the woofer section (plus another inductor for second pair of woofers) and second order electrical on the tweeter. Here is the response at about 3 feet, 1/48 octave smoothing. Ignore the SPL level. It is not accurate.

[5th element]

That looks pretty good, the room modes notwithstanding!

[Navy Guy]

That looks pretty good, the room modes notwithstanding!

Thanks! Yeah, that one at 60-80 Hz is pretty terrible. It's really wide compared to a most of them that I've seen and totally explains why everything sound like it has no bass in my new apartment.

[JonMarsh]

My old condo did some things like that, because the hallway leading off from the living room to the bedrooms formed a tuned bass trap...

[Navy Guy]

My old condo did some things like that, because the hallway leading off from the living room to the bedrooms formed a tuned bass trap...

I think mine might be the narrow stairwell leading upstairs.

[Navy Guy]

So I got my second cabinet sprayed outside on Sunday since the weather was nice, which means I didn't have to make a mess in my basement. The wife was appreciative of that I was missing a 0.10 mh inductor to hook up the pair of speakers so I went ahead and ordered the the crossover yesterday and should have them today or tomorrow from PE so I can actually start listening to a stereo pair this week sometime. I'm going to try some different part values to fill in the presensce area between 4-8 kHz a little. I think they might end up sounding a little too laid back with the depression there.

[cochinada]

Errrr... IMO I don't recommend trying to compensate the dip you observe on that frequency range by boosting the same on your speakers. It's the same principle as when one is trying to apply equalization. The only way to fix the problem is with some sort of acoustic treatment, otherwise the room will just keep absorbing the extra energy you will give it. At least this is what happened in my room, although I was trying to correct a low frequency dip so maybe I'm wrong anyways. :B

[Navy Guy]

The Boomsticks: 2.5-way high WAF w/ 4xRS100-8 and ND25FA tower

Errrr... IMO I don't recommend trying to compensate the dip you observe on that frequency range by boosting the same on your speakers. It's the same principle as when one is trying to apply equalization. The only way to fix the problem is with some sort of acoustic treatment, otherwise the room will just keep absorbing the extra energy you will give it. At least this is what happened in my room, although I was trying to correct a low frequency dip so maybe I'm wrong anyways. :B

That region isn't due to the room. It's a dip from the crossover. My gate time was 4.8 ms so I'm getting clean measurements without room effects that high up.

The crossover gave me the best phase tracking but I'll have to listen and see once I get the stereo pair set up if I want to make crossover adjustments or not. It's all purely speculation at this point, but I've found that depressions in this region can lead to a dull and 2d sound depending on how deep they are.

[Navy Guy]

So I've got the final crossover settled on and took some final measurements today to confirm. Measurements taken at 30 inches with 1/48th octave smoothing and are SPL accurate. After listening to these for a few weeks now and making a few minor adjustments, I'm pretty happy with how they sound.

These will be coming with me to InDIYana for anyone who is interested in hearing them.

[DS-21]

Nice work! Axial and polar FR both look very good, except for the fairly extreme narrowing of the tweeter above 10kHz where it really doesn't matter.

I feel bad for the B&W's standing next to them in that early pic.

Looks like a nice "scalable" component too: start as mains, move to surrounds.

[Navy Guy]

Nice work! Axial and polar FR both look very good, except for the fairly extreme narrowing of the tweeter above 10kHz where it really doesn't matter.

I feel bad for the B&W's standing next to them in that early pic.

Looks like a nice "scalable" component too: start as mains, move to surrounds.

Thanks! The narrowing isn't as bad as it seems. Those measurements are all the way out to 90 degrees off-axis, so at around 60 degrees, it's only down about 15 dB over the peak. 30 degrees, it's only down about 5 dB.

The B&W definitely are not as good. It's kind of a shame really. I've taken them apart and measured the drivers individually. The construction quality is good on the cabinet and the mid and tweeter exhibit pretty low distoriton and fairly smooth response in their operating range. However, their crossovers leave a lot to be desired. I bought them back before I started building and haven't replaced them yet for aesthetics rather than SQ reasons.

[Navy Guy]

I submitted all the info to the project showcase today and will post the full writeup soon it is easy to find all the info in one spot, but to wrap this up, here is the crossover and box diagram for these. The crossover was much simpler than I expected. I used a 0.1 uF and 0.22 uF capacitor in series to get the value I needed for the bottomless notch. A 0.1 uF was just a bit too large to hit the actual spot of the breakup. The notch probably wasn't necessary, but for $2, I'd prefer to just go ahead and use it. However, you can't remove it now because it does change the rolloff of the woofer if taken out. The crossover does dip to about 3.5 Ohms due to the small coil on the tweeter, but it is high in frequency and the phase angle isn't bad, so I don't think it will be a problem on any amp given the overall impedance everywhere else. I certainly didn't notice any issues on any of my amps I tested on.

[Browncoat]

Fantastic looking results! What are you listening impressions?

[Navy Guy]

Fantastic looking results! What are you listening impressions?

Thanks! I'm very happy with how they sound. The midrange on these are really nice and vocals have a real standout quality, even though they measure flat. I compared to my last build, the Standards, last night. I like these better overall. The bass is better on the Standards, but midrange on these are better. Highs could be a toss up between the two. I need to go back and take a second look at those now and see if I can make some improvements. The wide dispersion makes them great, at least IMO, for HT use. They also blend much better with my center than the B&Ws ever did. I played some video games on Sunday and tried panning around the sound. It is much more coherant moving from the center to L/R or L/R to surrounds than before. I posted a full writeup over on the PE board and in their project gallery with more pictures and build info. I'll try and copy it all over here sometime this week.

http://techtalk.parts-express.com/forum/speaker-project-gallery/1325813-the-boomsticks-a-high-waf-slim-tower-with-4x-dayton-rs100-8-and-nd25fa

[DigitalMaven]

I did a three way parallel crossover with a first order on the woofer/midrange and a third order on the tweeter/midrange and came up with this...



Am I wrong in thinking this way. I was wondering why 2.5 way was chosen?



Crossover components are...
woofer... 1.5 mh inductor
midrange... 68 uf , .8mh, 22uf, .20mh (1.2 ohms resistor before crossover)
Tweeter...12uf, .15mh, 22uf (.4 ohm resistor after crossover)

Inductors 18 gauge

Phase?

[Navy Guy]

The Boomsticks: 2.5-way high WAF w/ 4xRS100-8 and ND25FA tower

I did a three way parallel crossover with a first order on the woofer/midrange and a third order on the tweeter/midrange and came up with this...



Am I wrong in thinking this way. I was wondering why 2.5 way was chosen?





Crossover components are...
woofer... 1.5 mh inductor
midrange... 68 uf , .8mh, 22uf, .20mh (1.2 ohms resistor before crossover)
Tweeter...12uf, .15mh, 22uf (.4 ohm resistor after crossover)

Inductors 18 gauge

Phase?

I appreciate the effort to try and help. I received your PM as well. However, there are some issues with your sim. First, you are using the infinite baffle response of the drivers, not the in cabinet measured response or the response with simulated baffle losses and diffraction. Second, it looks like you either did not extract minimum phase or did not put in acoustic offsets based on how your phase lines up over the entire 20 Hz - 20 kHz range. When I put you listed values into a sim, I get a pretty different response and an impedance that dips to 1.6 Ohm. Not sure if you made a typo or not, but definitely not what you displayed.





There are a number of reasons I chose to do a 2.5-way rather than a 3-way. Doing a true 3-way would have resulted in a lower overall impedance with no additional gain in sensitivity. In addition, you would have traded off total output by reducing the number of woofers producing bass. So what you would end up with is still an 85 dB sensitive speaker. It would require twice the power to hit the same dB level because it is 4 Ohm now. And with only two small woofers reproducing bass, it would have over double the excursion requirements to hit the same output levels. This means more distortion, which is not a good thing. See graphs below for excursion at the same SPL.





In terms of the dips in the bass response you are seeing, that is a room mode from the measurement position. It is not indicative of the anechoic response of the speaker. I did not do a nearfield blend on these for the final measurements to capture a clean low end response. Unfortunately, the best place in my room to get a clean top end and low gate time is also the worst for a room mode.

As for your concern on the tweeter fs, the old rule of thumb of your crossover being 3x the fs is a little out dated. If you measure distortion, you can get a much better idea of how low you can cross. Coupled with the fact that this tweeter also has a well damped resonance, it makes it easier to cross closer to the fs. If the tweeter had a huge resonance peak, I might have used a LCR notch to suppress it, but this was not necessary here. You can also see from the distortion measurements that the tweeter has no issues with where it was crossed and I can hear no issues either.

Hopefully this doesn’t come across as defensive, I’m just trying to explain the design decisions you were asking about. Normally, I would prefer to go 3-way, as it tends to clean up the midrange, IMO. But in this case, it would have significantly compromised the speaker to do that.

[DigitalMaven]

I think you hastily threw together a reenactment of my crossover...

you have 85 db for the woofer which should be woofers in parallel for 90 db...


Here's mine



Your midrange is off because I think you missed the resistor before crossover of 1.2 ohm.



Here it is without resistor.



I learned a long time ago if you miss even one component everything can go wonky real quick.

What I need to learn from you is how to set up this minimum phase for better crossovers. Also, if your just doing a basic two way why would you need all these measurements...according to the speaker cookbook where people usually crossover 1500-3000 you really only have a .5 db difference between woofer and tweeter vs, having a huge difference in location of the tweeter on the baffle.

[Navy Guy]

I think you hastily threw together a reenactment of my crossover...

you have 85 db for the woofer which should be woofers in parallel for 90 db...
[ATTACH=CONFIG]27112[/ATTACH]

Here's mine

[ATTACH=CONFIG]27113[/ATTACH]

Your midrange is off because I think you missed the resistor before crossover of 1.2 ohm.

[ATTACH=CONFIG]27114[/ATTACH]

Here it is without resistor.

[ATTACH=CONFIG]27115[/ATTACH]

I learned a long time ago if you miss even one component everything can go wonky real quick.

What I need to learn from you is how to set up this minimum phase for better crossovers. Also, if your just doing a basic two way why would you need all these measurements...according to the speaker cookbook where people usually crossover 1500-3000 you really only have a .5 db difference between woofer and tweeter vs, having a huge difference in location of the tweeter on the baffle.

This was not a "hastily thrown thrown together re-enactment" as you so put it. As I said before, you have to simulate for baffle losses. Yes, you have two woofers in parallel, which would put you up to 90-91 dB, but then you have 6 dB of baffle losses which bring you back to 85 dB. If you don't know/understand what baffle losses are, I have a video up on my website explaining the concept. You are using infinite baffle measurements for your sims, which are not accurate for a free standing speaker.

There are several reasons to use actual measurements. They are always going to be more accurate than the manufacturer's data due to individual driver variances. They are used to find accoustic offsets between the woofer and tweeter. They already include baffle losses, so you don't end up doing what you have assumed here and getting an overly bright speaker. I don't understand what you are trying to say in your last sentance. What do you mean "having a huge difference in location of the tweeter on the baffle"?

[DigitalMaven]

This was not a "hastily thrown thrown together re-enactment" as you so put it. As I said before, you have to simulate for baffle losses. Yes, you have two woofers in parallel, which would put you up to 90-91 dB, but then you have 6 dB of baffle losses which bring you back to 85 dB. If you don't know/understand what baffle losses are, I have a video up on my website explaining the concept. You are using infinite baffle measurements for your sims, which are not accurate for a free standing speaker.

There are several reasons to use actual measurements. They are always going to be more accurate than the manufacturer's data due to individual driver variances. They are used to find accoustic offsets between the woofer and tweeter. They already include baffle losses, so you don't end up doing what you have assumed here and getting an overly bright speaker. I don't understand what you are trying to say in your last sentance. What do you mean "having a huge difference in location of the tweeter on the baffle"?

So your basically modeling for the full baffle step compensation? why? is that a real world practicality? Almost No one places their speakers 4 feet from the back wall and three feet from the side wall. I fully understand baffle step compensation but this was just a thrown together crossover with a theoretical possibility or conceptual idea of a three way. (In all fairness most three ways do not have this small of a baffle front for the woofer) also, you never mentioned whether the midrange was correct or inaccurate in your revision (it seems off to me as the db is too much as well as the midpoint has been shifted from 1000 to 2000hz). So maybe if the midrange was lower and shifted back to 1000hz and the speakers were moved closer to the back wall the measured sound might be closer to my crossover values and less of the frankensteinian crossover that you've displayed (minus the adjustment in a new crossover point for when the speaker is going from half space to full space). I also think that my crossover point should have been higher though because of the smaller baffle size which I was not thinking too much about at the time. If you look at it there is a slight increase of 1-2 db from 100-300hz plus whatever would be added by your enclosure design. I didn't spend anytime modeling any potential additional bumps in db due to enclosure or porting as this would take me some considerably more time than I wanted to on this exercise..

[Navy Guy]

So your basically modeling for the full baffle step compensation? why? is that a real world practicality? Almost No one places their speakers 4 feet from the back wall and three feet from the side wall. I fully understand baffle step compensation but this was just a thrown together crossover with a theoretical possibility or conceptual idea of a three way. (In all fairness most three ways do not have this small of a baffle front for the woofer) also, you never mentioned whether the midrange was correct or inaccurate in your revision (it seems off to me as the db is too much as well as the midpoint has been shifted from 1000 to 2000hz). So maybe if the midrange was lower and shifted back to 1000hz and the speakers were moved closer to the back wall the measured sound might be closer to my crossover values and less of the frankensteinian crossover that you've displayed (minus the adjustment in a new crossover point for when the speaker is going from half space to full space). I also think that my crossover point should have been higher though because of the smaller baffle size which I was not thinking too much about at the time. If you look at it there is a slight increase of 1-2 db from 100-300hz plus whatever would be added by your enclosure design. I didn't spend anytime modeling any potential additional bumps in db due to enclosure or porting as this would take me some considerably more time than I wanted to on this exercise..

You're right. What do I know... I mean, I took all these worthless measurements that aren't even needed. :roll: I'm sorry I've offended the crossover god who is too busy to be bothered to spend time simulating baffle losses and diffraction before throwing me this gift of the ultimate crossover to fix my poor attempt at speaker design. What was I thinking? I should just give up now.

[DigitalMaven]

You're right. What do I know... I mean, I took all these worthless measurements that aren't even needed. :roll: I'm sorry I've offended the crossover god who is too busy to be bothered to spend time simulating baffle losses and diffraction before throwing me this gift of the ultimate crossover to fix my poor attempt at speaker design. What was I thinking? I should just give up now.

I think your just taking this the wrong way...all I did was come up with an idea which was an alternative to your idea. I haven't spent the time like you have with your enclosure, your crossovers, your general situation and setup. But...when you start treating someone like they're a complete idiot, butcher some aspect of their crossover and not work with them your going to get a response. Be fair and others will be fair with you...I don't know everything and there are others on this board that know a helluva lot more than me (marsh and crew) but I do know enough to be dangerous due to experimentation and multiple years of research and I'm still learning more and more every day. I usually put things into perspective like bad, OK, good, better, and best. I've just seen so many different speakers and crossovers that I simply look at something and try to understand what the designer is trying to do. Trust me in that I liked what your trying to do and the look and design of your speaker. There's more than one way to crack a nut!

[fbov]

Well... my speakers are more like 6-8' from side walls and 3' from the wall behind, so perhaps full BSC is more common than you thought. I see it as a tool; my CC works better without it.

Every simulation is a guess, until you build it and confirm your prediction (or not). He who builds usually wins these arguments.

Have fun,
Frank

[DigitalMaven]

Well... my speakers are more like 6-8' from side walls and 3' from the wall behind, so perhaps full BSC is more common than you thought. I see it as a tool; my CC works better without it.

Every simulation is a guess, until you build it and confirm your prediction (or not). He who builds usually wins these arguments.

Have fun,
Frank

You've got a nice big room...maybe you've got one of those big JBL studio monitors that doesn't need a huge baffle step compensation. :>)

[Alaric]

From what little I've picked up hanging around here, that looks very nice! :T

[Navy Guy]

I think your just taking this the wrong way...all I did was come up with an idea which was an alternative to your idea. I haven't spent the time like you have with your enclosure, your crossovers, your general situation and setup. But...when you start treating someone like they're a complete idiot, butcher some aspect of their crossover and not work with them your going to get a response. Be fair and others will be fair with you...I don't know everything and there are others on this board that know a helluva lot more than me (marsh and crew) but I do know enough to be dangerous due to experimentation and multiple years of research and I'm still learning more and more every day. I usually put things into perspective like bad, OK, good, better, and best. I've just seen so many different speakers and crossovers that I simply look at something and try to understand what the designer is trying to do. Trust me in that I liked what your trying to do and the look and design of your speaker. There's more than one way to crack a nut!

Maybe I am taking it the wrong way, but I felt like you were doing the same thing to me. Your PM reads like I should check out your sim because it would be an improvement on my design. I don't think I was rude in my initial two responses. I just said that there were issues with your sim. I also said maybe there was a typo in something because my graphs came out significantly different than yours. But I still find fault in not simulating baffle losses or driver positions on a baffle. When I brought this up, and used results that simulated it, you claimed that I had done it wrong because it should be at 90 dB. To me, that makes me think that you didn't understand baffle losses. Again, I don't think I was rude in suggesting that you could check out a video I made to explain the topic or trying to make you sound like an idiot. Other than that, you asked why I made the design decisions I did, which I think I answered politely as well.

I'm sorry if it came across as being that way or that I was trying to make it sound like I know everything (which I definitely don't) and for my last response. Obviously conversing over the internet has some downsides.

To answer your last question about the real world practicality of full BSC, every speaker I've ever designed and placed any any room of various sizes need at least 3 dB of baffle step to sound right to me. In my old apartment, I always was around 5 db. In my current living room, slightly more than a full 6 dB actually sounds better. Something like a downward tilt sounds more natural too me. My living room sucks the bass out of everything. But even when I've built speakers to be pushed against a wall, I always thought 3 db sounded more natural. The room is the one place that adds the most variance, and it's hard to design for all situations without adding L-Pads or something. I think most people (as in non-audiophiles) tend to prefer exagerated bass over lean bass anyway, so having too much is usually less of a problem than having too little.