I recently posted a thread inquiring about building the Linkwitz LX521 baffle part and filling in the low end with a conventional subwoofer. Lots of helpful comments, but mixed predictions for success. Links supplied in that thread got me started reading about building open baffle speakers (not ALL of the 224 pages in the open baffle speaker thread, though), and while I have never build a speaker before, this encouraged me to build something from scratch.
I was pondering a Caladan or Pure Audio clone using the Beyma woofers from the Caladan and a GRS PT6825-8 mid/tweeter that many people seem to recommend, and then using a multichannel amp and a miniDSP for cross-over and EQ. Being a newbie, this lead to some initial questions (there probably will be more down the line):
1. The GRS PT6825-8 often seems to be combined with an additional tweeter, since there's a bit of fall-off after 10 kHz. Given that I don't hear much beyond 11 kHz (yes, I'm getting old) and the potential for EQ, can I safely omit the additional tweeter?
2. The Pure Audio speakers use modular panels for each driver, which I find very appealing, as the smaller panels will be easier to handle and allow to be individually angled. Putting the panels at an angle probably addresses some timing/phase alignment issues, but that can probably also be done with the DSP. Are there any other accoustic advantages/disadvantages? Is the small gap between the panels of any concern? The Trio10 has the two woofers on the bottom and the tweeter on top, the Trio15 has a woofer-tweeter-woofer arrangement. Is one arrangement superior to the other (when using 12" drivers, there are 10" in the Trio10, I believe)?
3. Where can I find those feet/stands that are shown on page 2 of this thread?
4. I plan to get an 8-channel amp (more flexibility for future changes). I could get a model with the cheaper 125W/c NC122MP Hypex modules and drive each woofer from a different channel. Would there be any benefit for eq'ing each woofer separately? I read a comment somewhere that the lower woofer might benefit from a 200 Hz cutoff, but no explanation or reason was given (due to being lower to the floor?).
I was pondering a Caladan or Pure Audio clone using the Beyma woofers from the Caladan and a GRS PT6825-8 mid/tweeter that many people seem to recommend, and then using a multichannel amp and a miniDSP for cross-over and EQ. Being a newbie, this lead to some initial questions (there probably will be more down the line):
1. The GRS PT6825-8 often seems to be combined with an additional tweeter, since there's a bit of fall-off after 10 kHz. Given that I don't hear much beyond 11 kHz (yes, I'm getting old) and the potential for EQ, can I safely omit the additional tweeter?
2. The Pure Audio speakers use modular panels for each driver, which I find very appealing, as the smaller panels will be easier to handle and allow to be individually angled. Putting the panels at an angle probably addresses some timing/phase alignment issues, but that can probably also be done with the DSP. Are there any other accoustic advantages/disadvantages? Is the small gap between the panels of any concern? The Trio10 has the two woofers on the bottom and the tweeter on top, the Trio15 has a woofer-tweeter-woofer arrangement. Is one arrangement superior to the other (when using 12" drivers, there are 10" in the Trio10, I believe)?
3. Where can I find those feet/stands that are shown on page 2 of this thread?
4. I plan to get an 8-channel amp (more flexibility for future changes). I could get a model with the cheaper 125W/c NC122MP Hypex modules and drive each woofer from a different channel. Would there be any benefit for eq'ing each woofer separately? I read a comment somewhere that the lower woofer might benefit from a 200 Hz cutoff, but no explanation or reason was given (due to being lower to the floor?).
It also has narrower vertical dispersion than a typical tweeter or the PT2522-4. That may or may not be important to you.
There will be differences. Whether that is a disadvantage could depend on whether you were already chasing specific acoustic conditions.
the feet look like the IsoAcoustics GAIA feet.
The stand looks to be something made for Clayton audio. Would be easy enough for any competent fabrication shop in your area to fab and powdercoat.
The stand looks to be something made for Clayton audio. Would be easy enough for any competent fabrication shop in your area to fab and powdercoat.
Here's what I've gleaned on open baffle - specifically full Dipole speakers. I'm happy to be corrected!
1. Nude drivers (i.e. baffleless) are best because they eliminate baffle diffraction problems and provide the most open front wall reflections back to the listener (therefore helping mask L/R speaker localisation)
2. All drivers must be dipole in operation. Back to back dome tweeters may have less distortion than dipole AMT/Ribbon speakers, but their polar behaviour becomes erratic as the wavelength approaches and becomes less than the membrane distance. You just cannot get dome tweeters close enough - even those with neo magnets
3. It's important to measure the back AND front of the driver to see how uniform its frequency response is. Some drivers have large magnets, stamped frames etc... that all affect the rear response
4. You'll likely need >= 2 18" drivers per side in a W/H frame if you want dipole bass to satisfying levels
5. IF not going dipole bass (i.e subwoofer(s) for 80Hz and down) - you'll still need at least a 3 way "top section" with likely 10-12" lower mid, 6.5" mid and dipole AMT of your choice.
1. Nude drivers (i.e. baffleless) are best because they eliminate baffle diffraction problems and provide the most open front wall reflections back to the listener (therefore helping mask L/R speaker localisation)
2. All drivers must be dipole in operation. Back to back dome tweeters may have less distortion than dipole AMT/Ribbon speakers, but their polar behaviour becomes erratic as the wavelength approaches and becomes less than the membrane distance. You just cannot get dome tweeters close enough - even those with neo magnets
3. It's important to measure the back AND front of the driver to see how uniform its frequency response is. Some drivers have large magnets, stamped frames etc... that all affect the rear response
4. You'll likely need >= 2 18" drivers per side in a W/H frame if you want dipole bass to satisfying levels
5. IF not going dipole bass (i.e subwoofer(s) for 80Hz and down) - you'll still need at least a 3 way "top section" with likely 10-12" lower mid, 6.5" mid and dipole AMT of your choice.
@Dave Bullet gets it right…….for go the double 18’s per side and use 4 smaller individual sealed subs as equandestant to the listening position as possible and low pass them in the 80-100hz range. The 10-12” OB midbass will take care of the perceived impact, slam and detail with direct sound.
Keep the upper mid/treble section as acoustically small as possible. My most recent prototyping has sent me in a new direction of the preferred vertical alignment of an OB is MTW where the listening axis is centered on the tweeter.
Keep the upper mid/treble section as acoustically small as possible. My most recent prototyping has sent me in a new direction of the preferred vertical alignment of an OB is MTW where the listening axis is centered on the tweeter.
Thanks!
Adding in a sub was the original idea with the partial LX521 build, so I could do that here as well. I'm also intrigued by the baffle-less approach (I saw a corresponding thread). I have a pile of surplus 80/20 sitting around and could quickly whip up a frame, suspend some drivers in it, and could start experimenting that way.
Adding in a sub was the original idea with the partial LX521 build, so I could do that here as well. I'm also intrigued by the baffle-less approach (I saw a corresponding thread). I have a pile of surplus 80/20 sitting around and could quickly whip up a frame, suspend some drivers in it, and could start experimenting that way.