Thanks, those are a set of Roche Bobois modular sofa chairs. I'm sure there is some collector out there that would be very upset with me for using them like this. I have repositioned them for better corner coverage.
I also have the speakers bi-amped now and I'm thoroughly impressed with the performance from $350 CDN worth of parts. I will say that the manufacturer's published specs is the biggest issue with inexpensive parts. The efficiency of the woofer was certainly not as published.
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I have moved from minimalist baffle to almost no baffle too. Especially for planars. Soundstage seems even better.
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For the SLOB Dipole, here is the measured crossover response. I tried several levels of padding resistors on the tweeter (2ohms, 3.3ohms, 4.7ohms) and found the midpoint 3.3ohms gave the best overall voicing.
Predicted impedance variation:
Predicted impedance variation:
My "proper" processor stopped doing more than cutting out immediately powering on a few years ago. I remembered the Hafler ambience and used a power amp with its own trim controls to Gerry rig one, until fixing the processor. No need. With a dipole behind me and about 10 feet behind that, I like the sound far better than the many DSP soundfields I had available before.
It nicely removes me from the latest tech upgrade treadmill too, and there's always a next "must have" format.
Looks very good. And as far as can be told from a video thru headphones, sounds very good too.
How would you describe the midbass, thinking up to 400Hz, vs a 15" OB on a small baffle? I was under the impression SLOB didn't do so well above 200Hz or so. But your speaker suggests otherwise.
The mid bass from the slob is terrific. Great “chest punch” as there are 4 directional ports that are front firing and equivalent of an 18in+ woofer on a 30in wide baffle.
Through careful design of the SLOB chamber dimensions in Akabak I saw that by minimizing driver diameter (6.5in vs 8in or larger) and minimizing internal volume (magnet in on one) the upper reach is extended to about 500Hz. Using this natural slot loaded band pass effect plus 2nd order electrical filter, we can get steep 4th order falloff to get rid of high frequency noise.
I have heard a dual 12in narrow width OB and this SLOB has bass that sounds much deeper in extension below 60Hz.
Through careful design of the SLOB chamber dimensions in Akabak I saw that by minimizing driver diameter (6.5in vs 8in or larger) and minimizing internal volume (magnet in on one) the upper reach is extended to about 500Hz. Using this natural slot loaded band pass effect plus 2nd order electrical filter, we can get steep 4th order falloff to get rid of high frequency noise.
I have heard a dual 12in narrow width OB and this SLOB has bass that sounds much deeper in extension below 60Hz.
I have tried narrow and wide baffle, SLOB and U baffle with samme 15 inch woofer. Narrow will never give good deep bass. Wide will is very good broadband, plays both deep and high. SLOB and U baffle to me, is very similar. They both play as deep as the wide baffle, but not as high. I prefer the looks of U baffle over SLOB and do not have the space for wide baffle
A 15in SLOB will have about 16in deep slot. The 1/4 wave cancellation is 210Hz max upper bandwidth, whereas 7in deep slot for 6.5in woofer is 480Hz. Hence, the reason why I went with lots of 6.5in woofers to allow 475Hz XO. The U is also a lot narrower with vertical aligned SLOB drivers.
Can I ask some very basic questions please?
- What's the difference between a SLOB and a Ripole?
- Do they both have the quarter wave resonance issue causing an uncontrollable peak that cant be EQ away?
- Would it make any difference lining the rear wall of the slot with eg a foam semicircular cut out insert that hugs the cone surround to minimise internal volume and extend the quarter wave resonance cut off?
No matter the chosen type there is a trade off. Small woofer dont normally go deep, since they usually have relatively high fs
It depends on how small you make the exit a lot. Too small and you get a peak, too large and you don’t get enough gain from slot loading. On mine, I did not have any issues with the peak.
Here is raw measurement (no filters):
A ripole is slot loading but a narrow baffle on the slot. It won’t go as low as U baffle slot loaded.
Nice. No wonder they sound so good
I assume you did some really good sims for the SLOB design? How well did reality comply with the sims?
Yes, it was simulated in Akabak, using basic dimensions dictated by the driver box dimensions. The main point was to keep the driver diameter small to allow high upper bandwidth. That you can calculate using speed of sound and distance from back of the box to front baffle exit and quarter wave equation. Take distance in meters, divide that into speed of sound (342m/sec) and divide that by 4. That’s the max frequency allowed by 1/4 wave cancellation. More details in this thread.
Thought I'd post an update on my build. I haven't finalised the EQ as my Focusrite failed and I'm waiting for the warranty claim to proceed.
The bridges are temporary cut down from an older project, the new bridges will be Tasmainian Oak. I'm pretty happy with the results so far, the speakers disappear in the room and sound almost the same no matter where you sit, the stereo image does not collapse into the speaker. No measurements due the failed Focusrite, currently using a very similar EQ/XO to the previous post.
The bridges are temporary cut down from an older project, the new bridges will be Tasmainian Oak. I'm pretty happy with the results so far, the speakers disappear in the room and sound almost the same no matter where you sit, the stereo image does not collapse into the speaker. No measurements due the failed Focusrite, currently using a very similar EQ/XO to the previous post.
Nice work warrjon! A modern planar take on the Orion! Interesting idea to use the smaller planar sideways - is that to give better up down dispersion?
Thanks......... The planar tweeter measures better turned on its side, both vertical and horizontal dispersion are better, especially because the XO is 7kHz from NEO8 to NEO3. I can't take the credit for this idea it was another DIYer that did this first, it works.
I tried very hard to not use Linkwitz LX521 style baffle but again it works well for the off axis response of the lower and upper midrange drivers. I also tried many iterations of top (NEO8 & 3) baffles with different shapes and this minimal baffle works well. When I get the new Focusrite I'll keep trying different top baffle profiles to see if I can smooth the off axis response better than it is.
One top baffle that is interesting used wings up top to separate front and rear tweeter waves, it has promise and I'll refine it. Unfortunately my Focusrite died while I was testing this baffle so it remains incomplete.