Hi there,
I have some bits and pieces from previous unfinished projects and I was thinking using some of using them in a new project 🙂 However, before I begin I would like your opinion.
My idea is to make a pair of active 2-way speakers of approx. 10 liters with a passive radiator.
Here is what I have:
The SW182BD+PR combo was tested in Voice Coil magazine with good results. From the test I quote:
“While the SW182 is billed as a subwoofer, a crossover frequency as high as 2kHz is certainly possible.” (http://www.wavecor.com/SW182BD01_in_Voice_Coil_Feb._2010.pdf)
The SB26 tweeter was tested by Jeff B (he tested the SB26STAC with alu faceplate, but I assume it performs similarly to the non-alu version I have). From the post I quote:
“Overall I think the SB26 is a very nice tweeter with good performance for the money […] When looking for a smaller, true 1" dome tweeter with very linear response, an attractive appearance, and an expected crossover point of 2kHz or higher I think it should be on your list for consideration.” (SB Acoustics SB26STAC Tweeter Tests)
I assume that both Voice Coil magazine and Jeff B are talking about passive crossovers here. This got me thinking that e.g. an active LR4 (or maybe LR8) @ 2kHz could work.
What are your thoughts on this project?
Thanks,
Søren
I have some bits and pieces from previous unfinished projects and I was thinking using some of using them in a new project 🙂 However, before I begin I would like your opinion.
My idea is to make a pair of active 2-way speakers of approx. 10 liters with a passive radiator.
Here is what I have:
- 2 x Wavecor SW182BD02 (SW182BD01_02)
- 2 x SB Acoustics SB26STC-C000-4 (SB Acoustics :: SB26STC-C000-4)
- 1 x MiniDSP 2x4 + miniDIGI combo (miniDSP/DIGI Combo | miniDSP)
- 2 x Wavecor PR182BD01 (PR182BD01)
- 1 x 4-channel power amp or 2 x stereo power amps
The SW182BD+PR combo was tested in Voice Coil magazine with good results. From the test I quote:
“While the SW182 is billed as a subwoofer, a crossover frequency as high as 2kHz is certainly possible.” (http://www.wavecor.com/SW182BD01_in_Voice_Coil_Feb._2010.pdf)
The SB26 tweeter was tested by Jeff B (he tested the SB26STAC with alu faceplate, but I assume it performs similarly to the non-alu version I have). From the post I quote:
“Overall I think the SB26 is a very nice tweeter with good performance for the money […] When looking for a smaller, true 1" dome tweeter with very linear response, an attractive appearance, and an expected crossover point of 2kHz or higher I think it should be on your list for consideration.” (SB Acoustics SB26STAC Tweeter Tests)
I assume that both Voice Coil magazine and Jeff B are talking about passive crossovers here. This got me thinking that e.g. an active LR4 (or maybe LR8) @ 2kHz could work.
What are your thoughts on this project?
Thanks,
Søren
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I think this is the correct link for your woofers:
http://www.wavecor.com/SW182BD01_02_specifications.pdf
http://www.wavecor.com/SW182BD01_02_specifications.pdf
The idea seems valid, but I'd keep a back up plan - 2kHz is the highest you'd want to use that woofer. The spec shows a suspiciously benign break up at 3kHz. Did the Voice Coil review show more dramatic break up?
The DSP should work better than most other options here - a digital high order crossover would be much better than a passive low order for keeping out junk that is only half an octave out of band.
My personal backup plan, if a 2kHz crossover didn't work out, would be to use a small mid-tweeter (Fountek, Tang Band or similar), and cross at about 500Hz with passive components, keeping the mini DSP, extra amp and tweeters for another day. Thus I'd build a rough test box first, so I could swap the HF drivers.
The microphone those mini DSP people sell is not bad, if you don't already have something. I'd be curious about whether you could measure the speaker sealed, then add the PR and tune the PR notch to fall at a frequency where your room gives a 15dB peak.
I'd like to know how it turns out, how the woofer performs. Wavecor is a brand I can pick up locally.
Edit - I just notice that you have posted about FAST systems before, which is basically my backup suggestion.
The DSP should work better than most other options here - a digital high order crossover would be much better than a passive low order for keeping out junk that is only half an octave out of band.
My personal backup plan, if a 2kHz crossover didn't work out, would be to use a small mid-tweeter (Fountek, Tang Band or similar), and cross at about 500Hz with passive components, keeping the mini DSP, extra amp and tweeters for another day. Thus I'd build a rough test box first, so I could swap the HF drivers.
The microphone those mini DSP people sell is not bad, if you don't already have something. I'd be curious about whether you could measure the speaker sealed, then add the PR and tune the PR notch to fall at a frequency where your room gives a 15dB peak.
I'd like to know how it turns out, how the woofer performs. Wavecor is a brand I can pick up locally.
Edit - I just notice that you have posted about FAST systems before, which is basically my backup suggestion.
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Not really. The Voice Coil FR test pretty much resembles that of the manufacturer. I have attached screenshots of both.
Yes, that’s another option. I actually have a few full-range drivers I could play around with, e.g. Fostex FF85WK or Wavecor FR070WA. However, I have built FAST speakers before and I’d like to go with a more traditional 2-way for this project. I often find that the full-range drivers lack the sparkle you get from a small dome tweeter.hollowboy said:
I have an ECM8000 and a basic measurement setup. I’m sure not what you mean by the room giving a 15dB peak? Are you referring to room gain?hollowboy said:
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If that breakup peak at 3200 Hz is accurate, there will be a corresponding 3rd harmonic distortion peak when playing at just over 1000hz (actually 1067 Hz). You can use the SW182BD02 in a two-way, but best to use it as a woofer in a three-way system.
Did you see the Voice Coil Test Bench link in the first post? http://www.wavecor.com/SW182BD01_in_..._Feb._2010.pdf
I have attached a screenshot of the response and harmonics as well as distortion test. You are right, there is a small peak in 3rd harmonic distortion of approx. 2% around 1.1kHz – is that good or bad? I’m no export in interpreting distortion plots. However, I do have faith in Vance Dickason when it comes to loudspeaker design 😉 When he says that “a crossover frequency as high as 2kHz is certainly possible” would you still advice against it?
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Anything near 1% would ordinarily be bad.. BUT,
VC's non-linear distortion testing is at the driver's limits.
If the driver was only being tested around 1 watt 1 meter, I'm sure the distortion would be much lower - qualifying as good or even excellent.
Most of the Wavecore driver's I've seen really only have problems below the driver's resonance where it's riding almost entirely on the spider - basically the bottom octave for any design you do. This doesn't make it a great speaker for lower freq. bass boost (..even if it represents as having good linear excursion).
If you hadn't already purchased the drivers, I would have suggested the Exodus Anarchy (..as opposed to the Wavecore - specifically for bass boost purposes at the lowest freq.s).
In any event, because this is an active design with digital eq. - the results should be very good.
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Soren, the harmonic distortion plot you posted is at a fundametal sound level of 110 dB, quite loud. As Scott mentioned, a much lower level is more applicable for most home listening, in the 85 to 95 dB range. This would drop the 2% 3rd harmonic for 1100 hz, which is quite high. 0.5% (-46dB) or lower distortion is a reasonable goal for 3rd harmonic. With 3rd harmonic desired at a lower level than 2nd harmonic.
No, I had not seen the harmonic chart that you posted. What I ventured was purely predictable. Undamped rigid metal cones that have the fundamental breakup peak also have the 3rd harmonic distortion peak at 1/3 the frequency. Some people are more sensitive to this 3rd harmonic distortion peak than others.
Years ago, before all these harmonic distortion plots were available, really before SoundEasy loudspeaker testing and crossover design software was available to the public, some people had issues with where magnesium or aluminum coned woofer were crossed over. They couldn't explain their observations, just that the speaker sounded better with a lower crossover. This happened in particular with the magnesium coned Seas W18EX001, where many applications crossed it over around 2 kHz. I remember some (with golden ears?) said that it sound better crossed over no higher than 1200 or 1400 Hz. Come to find out years later when the harmonic distortion plots were published for the W18EX001, there is a big 3rd harmonic distortion peak (-42dB) for the 1700 Hz fundamental. The fundamental frequency response had the tell-tale corresponding big breakup peak at 5 kHz.
Zaph|Audio
Remember the "SW" in the designation SW182BD stands for subwoofer, though it really has the range of a woofer. The WF182BD is their woofer or mid-woofer. The Wavecore SW series can be used as a great woofer:
http://www.htguide.com/forum/showth...nt-Reference-Thread-How-we-realized-the-Dream
No, I had not seen the harmonic chart that you posted. What I ventured was purely predictable. Undamped rigid metal cones that have the fundamental breakup peak also have the 3rd harmonic distortion peak at 1/3 the frequency. Some people are more sensitive to this 3rd harmonic distortion peak than others.
Years ago, before all these harmonic distortion plots were available, really before SoundEasy loudspeaker testing and crossover design software was available to the public, some people had issues with where magnesium or aluminum coned woofer were crossed over. They couldn't explain their observations, just that the speaker sounded better with a lower crossover. This happened in particular with the magnesium coned Seas W18EX001, where many applications crossed it over around 2 kHz. I remember some (with golden ears?) said that it sound better crossed over no higher than 1200 or 1400 Hz. Come to find out years later when the harmonic distortion plots were published for the W18EX001, there is a big 3rd harmonic distortion peak (-42dB) for the 1700 Hz fundamental. The fundamental frequency response had the tell-tale corresponding big breakup peak at 5 kHz.
Zaph|Audio
Remember the "SW" in the designation SW182BD stands for subwoofer, though it really has the range of a woofer. The WF182BD is their woofer or mid-woofer. The Wavecore SW series can be used as a great woofer:
http://www.htguide.com/forum/showth...nt-Reference-Thread-How-we-realized-the-Dream
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Hi,
Active acoustic LR4 will most certainly work well.
The electrical filter functions will not be LR4 at all.
rgds, sreten.
Fair enough. Another option could be a 3way using what you've got, sub - wideband - tweeter, active crossover down low and passive up high. I think one of the DSP's strengths is for low frequency crossovers, where passive components get as costly as the drivers.
Digital snobs could even use the DSP just for the bass driver(s) and keep the rest analogue.
Not exactly. When I measure bass in room, I get vast peaks and notches. What I'm wondering is if it would be possible to tune a PR so that its notch cancels one of these peaks. Maybe too much trouble (you'd have to do each speaker separately, and it wouldn't be valid if you moved the speaker to another room).
Thanks for clearing that up. It seems that at least it would be worth a try making a test cabinet for this setup. Regarding the problems of low frequency bass boost below Fs, I guess that won’t be much of an issue. The driver's Fs is at ~30Hz and I don’t expect to go any lower than that. I did a quick sim, which gave me an F3 of 35Hz.
So in other words I need to consider the actual response of each driver and not just implement textbook filters? I.e. I need to measure or at least use software with actual frequency response, is that what you mean?