I just read this article today -- I saw it on AudioCircle:
The Rational Audio System
Basically, the idea here is we have a 3-way system.
12" woofer in a 3 cu ft sealed enclosure -3 dB @ 35 Hz. Looks very similar to something like this:
GRS 12PR-8 12" Poly Cone Rubber Surround Woofer
In a separate box, he has a 4" midwife and 1" dome tweeter. The 4" is a Peerless, which looks to be similar to this:
Peerless 830992 4" GFC Cone HDS Woofer
And the tweeter is sort of like this:
Vifa Tymphany BC25SC06-04 1" Textile Dome Tweeter
He is using recycled speaker cabinets with new baffles resiliently mounted to the fronts.
The really interesting part to the setup is the FIR-based crossover approach. He's written some software to convolve the audio stream with FIR-based crossover filters.
Anyways I've been thinking of designing something similar. I've also done some reading on this site: Digital Crossover/EQ with Open-Source Software: HOWTO | Richard's Stuff
He does something similar with a Linux PC doing all the work, but is using IIR filters.
I would love to design a plugin for the Mac that does 6-channel convolution and FIR-based crossing over to a similar type of setup. He does not make the plug available to download, though, and it is Windows.
I've investigated using something like rePhase to generate the FIR filters, and that seems straightforward, I am just looking for ideas on this system, the notion of using a PC-based device to perform crossover and signal processing duties and also the basic speaker design.
The Rational Audio System
Basically, the idea here is we have a 3-way system.
12" woofer in a 3 cu ft sealed enclosure -3 dB @ 35 Hz. Looks very similar to something like this:
GRS 12PR-8 12" Poly Cone Rubber Surround Woofer
In a separate box, he has a 4" midwife and 1" dome tweeter. The 4" is a Peerless, which looks to be similar to this:
Peerless 830992 4" GFC Cone HDS Woofer
And the tweeter is sort of like this:
Vifa Tymphany BC25SC06-04 1" Textile Dome Tweeter
He is using recycled speaker cabinets with new baffles resiliently mounted to the fronts.
The really interesting part to the setup is the FIR-based crossover approach. He's written some software to convolve the audio stream with FIR-based crossover filters.
Anyways I've been thinking of designing something similar. I've also done some reading on this site: Digital Crossover/EQ with Open-Source Software: HOWTO | Richard's Stuff
He does something similar with a Linux PC doing all the work, but is using IIR filters.
I would love to design a plugin for the Mac that does 6-channel convolution and FIR-based crossing over to a similar type of setup. He does not make the plug available to download, though, and it is Windows.
I've investigated using something like rePhase to generate the FIR filters, and that seems straightforward, I am just looking for ideas on this system, the notion of using a PC-based device to perform crossover and signal processing duties and also the basic speaker design.
Interesting article, and the author can be forgiven for focussing on what is his area of expertise (SW) and maybe missing a few things. I certainly would not argue that a phase linear filter should be good, but he seems to have just thought about on axis response. But I suspect with a little more work he can make it even better.
As I used to lust after the old Kef reference speakers I approve of the look. And happy audiophiles is always good.
As I used to lust after the old Kef reference speakers I approve of the look. And happy audiophiles is always good.
Progress: Found a pair of beautiful Wharfedale w70d enclosures on craigslist. They are ~ 2.75 cu ft. inside and have great condition mahogany veneer. My plan is to remake the baffles and then put a 12" LF driver in there.
Considering two options:
1) Peerless SLS 12": https://www.madisoundspeakerstore.c...rless-sls-830669-12-woofer-coated-paper-cone/ -->looking at F3 @ 40Hz or so.
2) SB-Acoustics 12" https://www.madisoundspeakerstore.com/approx-12-woofers/sb-acoustics-sb34nrx75-6-12-woofer/ --> looking at F3 of 37 Hz or so.
With a stuffed box, we would be close to Q .71 I think. This would be a good starting point of the system.
The next big "what-if" is the DSP system. I am considering using a Mini PC like a zotac box and installing windows on it with the frequency allocator plug-in: DSP Crossover for PC. Frequency Allocator.
I also picked up a Pioneer D912K receiver on eBay after reading GLOWING reviews about its use for systems like this.
Still undecided about the MF and HF drivers, but one step at a time.
If I went the PC route, I would need a mini PC (Craigslist, hopefully), an ASIO audio interface, a copy of Windows, and the plugin.
Getting closer. Total system cost thus far:
Enclosure: $60
Amplifier: $70
Total: $130.
Considering two options:
1) Peerless SLS 12": https://www.madisoundspeakerstore.c...rless-sls-830669-12-woofer-coated-paper-cone/ -->looking at F3 @ 40Hz or so.
2) SB-Acoustics 12" https://www.madisoundspeakerstore.com/approx-12-woofers/sb-acoustics-sb34nrx75-6-12-woofer/ --> looking at F3 of 37 Hz or so.
With a stuffed box, we would be close to Q .71 I think. This would be a good starting point of the system.
The next big "what-if" is the DSP system. I am considering using a Mini PC like a zotac box and installing windows on it with the frequency allocator plug-in: DSP Crossover for PC. Frequency Allocator.
I also picked up a Pioneer D912K receiver on eBay after reading GLOWING reviews about its use for systems like this.
Still undecided about the MF and HF drivers, but one step at a time.
If I went the PC route, I would need a mini PC (Craigslist, hopefully), an ASIO audio interface, a copy of Windows, and the plugin.
Getting closer. Total system cost thus far:
Enclosure: $60
Amplifier: $70
Total: $130.
Hi,
I'd go with the Peerless and vent it low, ~ 22Hz,
DSP can sort out the eventual bass alignment.
Just wait for a decent pair of used speakers
to turn up for the upper cabinets and mid
and treble drivers, and remove the x/o's.
I'd suggest 6.5"/1" 2 ways with equal power
on all channels active. Way too much than
needed for the tweeter, but you wan't to be
xing/o low, around < 200Hz for bass to mid,
as you ideally need more bass power, and
the lower the x/o point the less of an issue.
rgds, sreten.
The mid treble drivers from this would be good :
https://sites.google.com/site/undefinition/tarkus
Both very good value drivers, if nice cabinets turn up.
.
I'd go with the Peerless and vent it low, ~ 22Hz,
DSP can sort out the eventual bass alignment.
Just wait for a decent pair of used speakers
to turn up for the upper cabinets and mid
and treble drivers, and remove the x/o's.
I'd suggest 6.5"/1" 2 ways with equal power
on all channels active. Way too much than
needed for the tweeter, but you wan't to be
xing/o low, around < 200Hz for bass to mid,
as you ideally need more bass power, and
the lower the x/o point the less of an issue.
rgds, sreten.
The mid treble drivers from this would be good :
https://sites.google.com/site/undefinition/tarkus
Both very good value drivers, if nice cabinets turn up.
.
Last edited:
Here are the cabinets. I'm going to make a new baffle to hold the 12" driver I get for them. By my measurements I get, 9.75" deep, 18" wide and 20.5" tall. That's only about 2.05 cu ft, which is a bit less than I thought it would be. I'll have to do some modeling in WinISD to see what that peerless does in a 2.05 cu ft enclosure.
Attachments
Thanks for the thoughts, @sreten. And for the link to the other loudspeaker project -- I'll have to look that.
BTW, here is how the Peerless 12" SLS simulates in a 2.05 cu ft. sealed enclosure. I get a -3 dB point @ 45 Hz or so, and a Q of .98. I think that is not that bad.
Stopped at Lowe's this morning on the way to work and picked up some things -- 2x2' birch ply for the new baffles, some sealing primer to paint the inside of the cabinets (slight mold or something smell when I took all the rotted drivers out.) I'm going to clean and then seal the insides. I also have to scrape off all the glued on insulation.
Then I am going to cut out much of the original baffle with my rotozip and just leave ~ 1.5" frame to screw and glue the new baffle on to. This should deal with much of the mildew issue, because a lot of it is on the back of the baffle.
I am going to brace the cabinet a bit more because right now there is nothing.
Unless anyone sees any major issues with the 12" SLS speakers, I think I am going to go for them.
I also have to make a new binding post holder and get beefier binding posts to hook up the woofers.
BTW, here is how the Peerless 12" SLS simulates in a 2.05 cu ft. sealed enclosure. I get a -3 dB point @ 45 Hz or so, and a Q of .98. I think that is not that bad.
Stopped at Lowe's this morning on the way to work and picked up some things -- 2x2' birch ply for the new baffles, some sealing primer to paint the inside of the cabinets (slight mold or something smell when I took all the rotted drivers out.) I'm going to clean and then seal the insides. I also have to scrape off all the glued on insulation.
Then I am going to cut out much of the original baffle with my rotozip and just leave ~ 1.5" frame to screw and glue the new baffle on to. This should deal with much of the mildew issue, because a lot of it is on the back of the baffle.
I am going to brace the cabinet a bit more because right now there is nothing.
Unless anyone sees any major issues with the 12" SLS speakers, I think I am going to go for them.
I also have to make a new binding post holder and get beefier binding posts to hook up the woofers.
You can do convolution using rephase (google "rephase") and applying it in foobar or Jriver media center. I am using this with a 3-way:
http://www.diyaudio.com/forums/multi-way/258246-corner-expanding-line-array-kef-q100.html
And you can read about the PC crossover setup here:
http://www.diyaudio.com/forums/pc-based/256809-setting-up-pc-based-multichannel-dsp-system.html
I am not that savy with Linux, though I could be if I put in the effort, so, the aforementioned solution works very well for me.
http://www.diyaudio.com/forums/multi-way/258246-corner-expanding-line-array-kef-q100.html
And you can read about the PC crossover setup here:
http://www.diyaudio.com/forums/pc-based/256809-setting-up-pc-based-multichannel-dsp-system.html
I am not that savy with Linux, though I could be if I put in the effort, so, the aforementioned solution works very well for me.
Thanks @ra7 -- I appreciate the links. Why not just use the Frequency Allocator, thought, it seems to tick all the right boxes?
*Phase linearization
*Up to a 4-way crossover
*Reasonably priced
*Import FRD files to help design filters in the product
I've tried the Linux approach as well -- I got pretty far. I was using a Zotac Zbox Nano for the mini PC but the fan on it was REALLY loud. I am currently trying to find an older laptop to run this, as Jay has recommended.
I still have the option to use that with linux. Having the laptop is nice, integrated keyboard, mouse and monitor, no fan noise etc.
I have a couple of options here. The allocator just seems like it was a turnkey solution that would do everything.
I need to keep researching.
*Phase linearization
*Up to a 4-way crossover
*Reasonably priced
*Import FRD files to help design filters in the product
I've tried the Linux approach as well -- I got pretty far. I was using a Zotac Zbox Nano for the mini PC but the fan on it was REALLY loud. I am currently trying to find an older laptop to run this, as Jay has recommended.
I still have the option to use that with linux. Having the laptop is nice, integrated keyboard, mouse and monitor, no fan noise etc.
I have a couple of options here. The allocator just seems like it was a turnkey solution that would do everything.
I need to keep researching.
Considering the following for drivers:
12" Peerless SLS in the lower sealed box (40Hz-175Hz):
Peerless 830669 12" Paper Cone SLS Subwoofer
5" Dayton Reference woofer for the midrange driver(175Hz-2000Hz):
Dayton Audio RS125P-4 5" Reference Paper Woofer 4 Ohm
1 1/8" Dayton Silk Dome Tweeter (2000Hz - 20kHz):
Dayton Audio RS28F-4 1-1/8" Silk Dome Tweeter
Total driver cost is $372. I'm a bit concerned about the low sensitivity of the midrange. Maybe I will keep looking.
Also need to get 2 sets of binding posts for the upper cabinets, and a 20 uF protection cap for the tweeter.
12" Peerless SLS in the lower sealed box (40Hz-175Hz):
Peerless 830669 12" Paper Cone SLS Subwoofer
5" Dayton Reference woofer for the midrange driver(175Hz-2000Hz):
Dayton Audio RS125P-4 5" Reference Paper Woofer 4 Ohm
1 1/8" Dayton Silk Dome Tweeter (2000Hz - 20kHz):
Dayton Audio RS28F-4 1-1/8" Silk Dome Tweeter
Total driver cost is $372. I'm a bit concerned about the low sensitivity of the midrange. Maybe I will keep looking.
Also need to get 2 sets of binding posts for the upper cabinets, and a 20 uF protection cap for the tweeter.
I played around with Allocator a few years ago but ended up going with JRiver. It isn't as intuitive as Allocator and doesn't have any simulation capability but once I dug into it I found it was more powerful than Allocator. Plus, it can do everything an avr can (besides amplification of course) and then some.
I forget how Allocator works....isn't it a VST plugin?
I forget how Allocator works....isn't it a VST plugin?
A passive RALS from Germany
Symphony 84 - August 2014 - Lautsprecherbau-Magazin 2014 | Lautsprecherbau
Symphony 84 - August 2014 - Lautsprecherbau-Magazin 2014 | Lautsprecherbau
An externally hosted image should be here but it was not working when we last tested it.
The Allocator is a VST plugin.
I'm curious why you think JRiver is more powerful than the Allocator. I understand they are really two different tools -- I still have a decision to make about where to house my music library/streaming services.
Right now my whole music library lives either on my Mac desktop (in iTunes) or in my Vinyl collection.
Although I have been investigating looking at something like Tidal for a streaming service.
I'm curious why you think JRiver is more powerful than the Allocator. I understand they are really two different tools -- I still have a decision to make about where to house my music library/streaming services.
Right now my whole music library lives either on my Mac desktop (in iTunes) or in my Vinyl collection.
Although I have been investigating looking at something like Tidal for a streaming service.
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