Thanks, Dave...
You know I agree with the sentiments you shared in reply. I was not spreading false information.
Later,
Wolf
You know I agree with the sentiments you shared in reply. I was not spreading false information.
Later,
Wolf
Hi Dave. I'm almost done building these and I'm just a bit stuck on the tweeter modifications. When I put the ring of felt (yarn, in my case) around the top of the tweeter, do I put the little plastic piece back in as well? Or do I leave it open?
Be careful with that yarn! It looks like it might be too tall and could contact the dome, especially at the joint, it's hard to tell just by looking at the photo and comparing to mine. It might work, but yarn is going to be reflective to a fair degree. But as long as it does not contact the dome, it's probably better than not using anything there. If the diameter were a bit smaller, leaving a bit more of the pole piece surface exposed, it might clear.
I doubt that you can reinstall the "mushroom" plug, but part of the mod and one that is required is to stuff the vent. The yarn would simply block the remaining vent opening if you reinstalled it.
What is required is to stuff the vent and leave the plug off. I had used lamb's wool for years, but have found that real cotton can be nearly as effective. As I indicated, the cotton that comes in aspirin and medicine bottles is nearly ideal as far as cotton goes. If you can't get some of that, you'll need to take regular cotton and fluff (stretch) it out so that it's somewhat the same density.
Again, the cotton (or lamb's wool) is needed, the felt on the top of the pole piece could be considered optional.
Dave
I doubt that you can reinstall the "mushroom" plug, but part of the mod and one that is required is to stuff the vent. The yarn would simply block the remaining vent opening if you reinstalled it.
What is required is to stuff the vent and leave the plug off. I had used lamb's wool for years, but have found that real cotton can be nearly as effective. As I indicated, the cotton that comes in aspirin and medicine bottles is nearly ideal as far as cotton goes. If you can't get some of that, you'll need to take regular cotton and fluff (stretch) it out so that it's somewhat the same density.
Again, the cotton (or lamb's wool) is needed, the felt on the top of the pole piece could be considered optional.
Dave
I followed your ideas and nixed the yarn. instead, I just took some excess cotton and squished it to make a little rope and used that. I honestly can't tell a difference between before and after, but I'm sure the difference is there! Under what conditions did you notice the most change or advantage to having modded the tweeter?
I never used the tweeter in a system before modding it. That comes first, the design follows, the same thing I do when I use felt on a baffle for diffraction control. But the latter allows for immediate changes.
That's the problem with relying only on perception. There's too much time in between if you listen, then mod a tweeter.
That said, changes shouldn't be large, as I showed at my site on the tweaks page. I would expect that before the mod, there might have been a dip centered around 1K, with the mod a return to a flatter response due to the change in raw response coupled with the interaction change of the Fs with the crossover. There should also be something of a bump up from 2-3.5K, so a bit more presence might be noticeable.
Another benefit, at least with mine, was the unit-to-unit consistency improvement. This would be a lot harder to characterize, since it would affect imaging in a music-dependent nature, related to balance between the two tweeters. The differences were as shown:
Original tweeter differences:
Tweeter differences after the mods:
You can see that before the mods, the tweeters were 0.5+ db different from 1.5K to 10K (ignoring the large deviations) on average. After the mods, they were basically equal, except for a bit remaining from 1-2K, what I consider a big improvement.
Did you stuff the pole-piece vent?
The more important questions I would have is how do you like the system, which box alignment and which crossover did you use?
Dave
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I did. I used some cotton from a Tylenol bottle like you suggested. it was quite a bit larger than would fit, so I cut it down a bit and fluffed it up some. I then used some of that to ring the top instead of using yarn.
As far as how do I like the system, I don't know yet! I decided to bi-amp instead of using a passive XO. I'll be using a Behringer DCX2496 to mimic the LR4@2k. That allows me some extra room for expansion in the future since I'll have an extra amp, and was also about $40 cheaper than XO components. Since I'm buying the DCX anyway for the subs, I figured I'd just leave it. What I can say, though, is that the sound quality is incredible. It's not even stuffed yet and it's already miles ahead of my previous system (Logitech, granted, but still a huge difference). And that's without the tweeters running. I don't have the DCX yet, so I'm not running the tweeters and mids at the same time. I don't want to risk blowing out the tweeters. I'll let you know how it sounds when the tweeter amp and the DCX come.
One thing I am considering, however, is measuring the in room response myself and then crossing over at whatever measurements I get from the tweeter and woofer. My room is very small and I'm not sure how I'll be able to place the speakers so it may be better to just build my own XO. I'm 99% sure I'll use an LR4, but not sure at what frequency.
Do you have pics of your finished build? I'm putting primer on today so my vinyl wrap has something to stick to other than MDF. I can't decide between a matte white or a matte black/grey. Which would you do?
I'm not a fan of white, partly because it shows dust and dirt so clearly. Once I finished the design, I set it aside to go on to my current system and more driver tweaking, so I never added a finish, though I'm using it in one room. I've had that on my to-do list for a long time. I also have a tendency to start the next system before completing the finish of the current one. The work of system design and driver tweaking hold much more appeal than woodworking, since I only have an old, small garage in which to do that. That also means about 5-6 months of the year when it's just too cold to do that as well.
Dave
I always have thoughts of doing a nice veneer finish, but that takes more time than I seem to find time to do.
My main systems have always been 3-ways. Currently it's a quasi-dipole 3-way. I don't often do passive crossovers now that I have the Ultimate Equalizer (Bodzio Software). I have a dedicated PC for that.
I finished designing it earlier this year and, of course, it's still bare mdf. 😱 I can't decide if I should finish the mdf or buy good quality plywood and re-build it from that. Since there's no box, the woodworking is much easier.
It was supposed to me my experiment with dipoles. I've got a 4-way planned, but this one has been good enough that I've delayed jumping into the 4-way.
Dave
It's superb. I used passive crossovers for many years. I first acquired SoundEasy largely for its built-in digital filter emulator so that I could audition designs before constructing the crossover. The 3-way digital equalizer was added later. Once I started using that and due to its ease of use, I eventually stopped making passives for the most part. With the newest Ultimate Equalizer (up to 4-way in the current version), I've now moved to a dedicated PC.
I had a dipole before I started designing my own systems, an Apogee Acoustics Centaurus Major (ribbon from 200Hz up). I still wish I had them for comparisons. Dipole is my favorite. Aside from ease of construction, they are better than any box system I've had, including any of my older ones. However, I likely would not have ventured into this without SoundEasy/Ultimate Equalizer. They make dipoles much easier to do, since the dipole peak EQ and Linkwitz-Transform type extensions are a snap.
Dave
Sounds like a great setup. I'd love to be able to use a dedicated PC, but I have lots of other components that I'm using with these speakers so unfortunately that isn't an option. I take it you use your speakers mostly for music and maybe the occasional movie?
What's the difference in sound like using a dipole vs. something like the Chameleons? I'm curious as to why you designed the Chameleons in the first place, given your preference to dipoles.
One more question, if I may. I'm looking at doing a similar active with a miniDSP (originally a DCX2496, but the miniDSP is much cheaper and simpler to use). Currently, designing XO's is quite easy, however I'm unsure of what type to use for the subwoofer low-pass. LR4 gives a very nice curve, but LR8 is much steeper. Is there any advantage to using an LR8 since I can cut off the woofers much sharper or would it be better to use LR4 to get that nice rolloff. Of course there's also Butterworth, but I'm not sure that an odd-order XO would be the way to go given the even-order everywhere else.
I have multiple components as well, Roku music server, CD player, tuner and record player. There are various ways in which to connect and use it. My setup uses the digital input with digital switching upstream as I have an A/D converter with 96KHz sample rate for the analog sources.
They're dedicated to music only in my main system.
Dipoles are a bit more "diffuse" to use that term. The imaging isn't as precise, but it's a more open sound and to me a bit more realistic sounding. Room and placement issues are different.
The drivers were all donated. I had been given the tweeters for testing/tweaking. The woofers were offered later to come up with an all-SB design. I decided that it would be a good time to detail the steps including tweaking a tweeter, the diffraction control option I use and the various box alignments. The multiple crossover options came about due to the many tests I made, since SoundEasy makes it easy to audition them before constructing a passive one. The SB midwoofer is a bit unusual, it sits on the fence between closed box and reflex (PR/ported) use.
The subwoofer is going to have to roll off a bit high, maybe 85Hz +/- and will need experimentation. It's also going to depend partly on which box type you used, closed or reflex. You should be able to experiment rather easily. I'm not a fan of high order lowpass in a sub. Room modes come into play as does the sub location, so all I can suggest is a lot of experimentation with sub location, slope and Fc. Run the mains full range, don't highpass them.
Dave
I've been tempted to try something like this as I've got all kinds of computer hardware sitting around. I've got a couple of questions though, since you've done it.
SoundEasy handles all the crossover and eq functions? (edit: oh, ultimate eq.) What sort of sound card do you have in this machine?
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SE and the UE work with various cards. There's a test program that you can download at Bodzio to test an installed card. I'm using the Delta 410. The Delta 1010 is known to work well as some others. Check the site, I believe that there's a list of tested cards.
SE will emulate passives as well as having the original version of the Ultimate Equalizer, a 3-way version. The UE v2 is currently 4-way, but a new version in beta, I think, will have additional capabilities, not yet released.
Both of these do the crossover, EQ and can also be linear phase for certain crossovers, the choice is yours. I'm using it in my dipoles with an LR8 @1200, linear phase. My drivers are roughly aligned for acoustic centers.
This is linear (red) vs. minimum-phase (blue), mid/tweeter only when I was testing the M/T crossover:
I don't show the W/M due to reflections since it's crossed at 350 and I can't show below 300Hz at best in my room.
Polar plot, 500-20K, not normalized:
Polar plot, 500-20K, normalized to the on-axis:
Dave
Interesting. i just bought a DCX to do the work so we'll see how that handles it.
On another note, how much stuffing did you use/recommend? I scoured the site for the Chameleons and couldn't find anything on how much stuffing to use.
On another note, how much stuffing did you use/recommend? I scoured the site for the Chameleons and couldn't find anything on how much stuffing to use.
I've not measured a closed box version, I worked with the PR version the whole time. Unibox shows roughly what the closed box response will be "fully stuffed", I listed that and the ported version if someone preferred either of those. I'm not sure of the exact amount needed for the closed box. It partly depends on what box Q you want, the Unibox response is for a classic Q=0.7, but you have a little room to play with the Q. Too little stuffing, though, and box resonances could become an issue.
What I did for the PR version was a bit of trial-and-error as well. I stuffed the upper section behind the tweeter to damp the long dimension resonance to some degree. It wasn't showing up in a significant way in the measurements, however. The resonance from front baffle to back baffle was rather strong, so I put stuffing only between driver and back baffle, in the center, maybe filling half the total distance. This was more effective than I expected. If you use a PR you should do this and do it so that it doesn't move, as it is most effective in the middle. I put enough to go from bottom panel to the horizontal brace. This held it in place well enough. The frequencies in the PR pass-band are largely unaffected by this amount of stuffing.
Dave
I built this design
I built a pair of these for a wedding present for my sister. I did the whole thing in 4 weeks - quickest project ever because I had a deadline!
I built the 2000 Hz Alternate crossover design, mainly because it required the least parts and also because the power handling is a bit higher.
I was quite happy with the result but unfortunately didn't get much time to listen to them, only a few hours (didn't do any measurements either). They sounded good overall, the only thing I found odd was a "clap" sound in the music was a bit muffled when I compared the sound to another 3-way speaker. I can say that my sister and her husband are very impressed with them! I'm a bit more critical because I built them and have a few other speakers to compare them to. They only had laptop speakers before. I drive them with a Topping TP60 amplifier.
I used the SB26STC-C000-4 tweeter and the SB17NRXC35-8 woofer.
I didn't do the tweeter modification because I didn't have time and felt a bit uncomfortable about pulling it apart. The baffle layout wasn't based on the original design, I just guessed where to put the tweeter.
Do you have any suggestions about how the crossover design could be modified to cater for the differences between the SB25 and SB26 tweeter?
I was thinking I might try and simulate the crossover in software.
I'm planning to build another one or two of these because it's a relatively cheap design and I already have the timber.
I'm trying to figure out whether I should change anything in the crossover design before I build the next pair.
Photos here:
I built a pair of these for a wedding present for my sister. I did the whole thing in 4 weeks - quickest project ever because I had a deadline!
I built the 2000 Hz Alternate crossover design, mainly because it required the least parts and also because the power handling is a bit higher.
I was quite happy with the result but unfortunately didn't get much time to listen to them, only a few hours (didn't do any measurements either). They sounded good overall, the only thing I found odd was a "clap" sound in the music was a bit muffled when I compared the sound to another 3-way speaker. I can say that my sister and her husband are very impressed with them! I'm a bit more critical because I built them and have a few other speakers to compare them to. They only had laptop speakers before. I drive them with a Topping TP60 amplifier.
I used the SB26STC-C000-4 tweeter and the SB17NRXC35-8 woofer.
I didn't do the tweeter modification because I didn't have time and felt a bit uncomfortable about pulling it apart. The baffle layout wasn't based on the original design, I just guessed where to put the tweeter.
Do you have any suggestions about how the crossover design could be modified to cater for the differences between the SB25 and SB26 tweeter?
I was thinking I might try and simulate the crossover in software.
I'm planning to build another one or two of these because it's a relatively cheap design and I already have the timber.
I'm trying to figure out whether I should change anything in the crossover design before I build the next pair.
Photos here:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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