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3-Way Driver Selection
Hello, I’m planning on building 3-Way Speakers for my Left, Right, and Center channels here at home, all ported btw. I’m in the process of building a DIY home theater in my living room. The goal is to save a couple of bucks given I have the wood working and audio tools to build speakers (yes mic, DATSv3, stands, laptop, appropriate programs). I need help/suggestions with my current driver selection for this project, at the moment I have planned to go with the Dayton Audio RST28F-4 (tweeter), Dayton Audio RS100-8 (Midrange), and Dayton Audio SIG180-4 (Woofer). I know that I could very possible just do a 2way with the rst28f and the sig180, however I’m set on doing a 3way at all costs (I understand more difficult and more costly).
I’m not experienced enough to know why I would or wouldn’t use these drivers together, I know all of their frequency responses are good matches with one another, specially in a 3way system with a full range as the mid. From my untrained eye these are perfect for a good set of 3ways, but what are you guy’s thoughts ? I recently used the Dayton Audio DC28F-8 in another 3way and thought the sound was incredible but have heard that the Dayton Audio RST28F-4 might be a little better, not to mention it has that grill for durability.
I have built a set of 2ways in the past using a Dayton Audio ND25FA-4 and a Dayton Audio TCP115-8 (pictures attached). I have learned all I know from AudioJudgement and his courses on UDEMY as well as Toids and other audio youtubers (plenty of hours of youtube and UDEMY).
I recently built a set of 3ways using the Dayton Audio DC28F-8 (tweeter, Dayton Audio PC105-8 (midrange), and Dayton Audio SIG150-4 (woofer). I just built them so I haven’t done measurements to see how close I got to the FRD graph I had modeled in xsim, but so far they sound amazing. The only issue I saw with these was my port design could’ve used some polishing but nothing too problematic, the other slight concern was that lowest impedance (modeled) was 3.6ohm which I know is super low but so far my amps and avr have handled it no problem at max volume.
****I know my x-over design could use some work, I’m working on it, also I want to keep component count as low as possible to save some extra bucks***
*** Reason I’m using sig180 is because of the 80w rms, my avr can do 100watts into 9 channels at 4ohm, so I want to stay a little below that, its the Emotiva MR1L. Also I don’t want gigantic speakers because I have limited room.
***I will be using 2 UM12-22 subs powered by a Crown XLS 1502 amp. But this might be irrelevant info.
My goal was to “Practice” and make a couple of speakers before attempting to build a “final” set of speakers for my home theater. I have all of the electrical components so I just have to design and build the speakers themselves. I just want to make sure my driver selection seems compatible enough. I also want to stick with drivers that have simple circular shapes. The only exception to this are truncated drivers, the tweeter to be specific for space savings on the center channel. One concern I have is the impedance being very low like on my last set of 3ways, this time I will use an 8ohm driver for the midrange instead of a 4ohm to ease up on the load, but since we’re trading the 4ohm DC28 with the 4ohm RST28F who knows if it’ll make a difference.
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5 Replies
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@herman I don’t see any glaring issues with the drivers you are using. Just don’t forget to measure your offsets when designing your crossover. That will be very important. Also feel free to post some measurements as you go, so we can take a look at them. Your two way, response does not appear to really take into baffle step. I would be very interested in seeing a final measurement on them. I think you could tune those a little better than what they are now. But if you are happy with them, that is all that really matters.
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Yea I forgot to post the final measurements. They were very much spot on, they’ll be attached here. But yes I haven’t delved into doing doing crazy complicated corrections, when I design my speakers I actually use these excel spreadsheets created by Marius from AudioJudgement on youtube, I believe one of them does correction for the nearfield measurements but I haven’t done else, there aren’t enough tutorials easy to follow (as a video) that I have found yet.
One thing I’m a little worried about is designing for speakers with multiple drivers of the same type. Say a center channel with two woofers or a regular bookshelf with 2 woofers or even two ports. Finding the offset I know how to do, is the process the same when it comes to multiple woofers? Just add or subtract offset until the system FRD matches the FRD of the drivers in parallel ? What about when creating a full frequency response when there’s 2 ports or more ? I personally planned on having to ports for the center channel. I don’t have any designs as of this moment though.
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The ports won’t affect the crossover. Of course, it is best to take the measurements in the final box.
If you are using multiple woofers and they are playing the same frequency then you can treat them as 1 woofer. The main caveat to that is if they are not playing the same frequency.
Your final response there are a few areas of concern, if you don’t mind me saying. The first is the bass is much lower than the rest of the system. It would appear you have not properly taken into account baffle step. And because of that this speaker will be more forward.
Second, I am assuming the red is the captured response and the blue was the intended. IF that is the case, it would seem your crossover is not aligned correctly and is out of phase. It appears you are crossing over around 1.7Khz (or there about). That red peak that is not on the intended/simulated response would show that the offset you were accounting for was off.
The easiest way to check is to hook it up to a microphone. Take a measurement on axis and slowly go off axis. My suspicion is that you are going to start seeing deviations there. Meaning, the frequency response will start to dip or peak (most likely dip) as you go off axis at that same 1.7Khz spot. If my suspicions are correct, you would be better suited to redesign the crossover. Or make some minor changes to what you have to at least get it in phase.
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How does one even do baffle step compensation ? And you’re probably correct, these were the first speakers I made, though its a shame they were not aligned properly, I really did try to match the curves in xsim when I was adding offset to the drivers to align them with the parallel wired measurement.
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@Herman Let me try to help you with baffle step. Impulse Audio did a great job with a video a while ago: https://youtu.be/sttbT1ONP80?si=A9sNR9J83tC-Hzjd
As far showing it on your response, we can see it start to rise around 600 hertz to the crossover point. Typically you bring this down with your crossover design on the woofer. Meaning you work with the inductor and capacitor value to bring down that rise and level it off with the rest of the system. That is part of the reason your midrange is so much higher than the rest of the graph.
I hope this helps.
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