From the pape — they do a nice job of outlining the benefits.r:
Note that 3 of the 6 dB come from the amplifier outputting 2x the power into half the impedance.
dave
Note that 3 of the 6 dB come from the amplifier outputting 2x the power into half the impedance.
dave
Well, marketing is pointing out the good things and omitting fine details.
That’s why KC62 has integrated 1000W RMS D class amp. You need that to move two cones to their 30 mm Xmax in a very small closed box.
Drawing the soundfield of the loudspeakers drivers radiation in 3D in the room is the rational approach, comparing the commercial adds or speculate about people beliefs is another story IMHO.
Very few 18" drivers have the Xmax to equal the Vd of a 21" driver, given that the area of the latter has a 50% greater Sd, and very high excursion creates it's own problems anyway. I have never seen any measurements of the supposed acoustical benefits of opposed reaction-cancelling drivers, although intuitively I feel that there should be advantages.
small subwoofers always remind me little chihuahua trying to be big woofer 🙂
anyone heard that tiny devialet? whatever they called it? reactor? more like little vibrator...with 900 watts
guess dave would like it, since small subs work for him in a big room
If the xMax of the 18 is the sme as the 21 and you have 2 of them then the math says they have the same Vd.
And given we are talking about a small room with big woofers you ar enever going to be palying them anywhere ear xMax so your argument is theoretical.
And it seems you have not grooked the HUGE advantages active reaction force cancelation. It outweighs, IMO, and extra Vd from a single larger driver.
dave
They did not impress in a short demo. But it was a poor room, poorly set-up with unknown ancillary equipment. The 8K TV next to it was nice.
dave
The Dayton Reference 8 RF look pretty good to suit my sealed box plans. I'll buy one after my wallet has time to play a little catch up.
Once I get my subwoofer amplification/equalization all set up and out of the way I'll experiment with all kinds of subs up to 15" JBLs.
But first some Dayton 8's https://www.daytonaudio.com/product/117/rss210hf-4-8-reference-series-hf-subwoofer-4-ohm to join the others in the small sub stable. The goal is 4. All on class D power.
I've been very happy with results from small subs in the past. As little as one single 8" bass reflex sub by Energy. That one changed some of my preconceived sub notions. The esw-8 are capable little guys.
All but the sub mentioned had sealed boxes. I achieve fast punchy articulate bass with 8s. But of course many other factors are at play. The room is 9x13x8 feet.
I should like where my current bass journey takes me.
Once I get my subwoofer amplification/equalization all set up and out of the way I'll experiment with all kinds of subs up to 15" JBLs.
But first some Dayton 8's https://www.daytonaudio.com/product/117/rss210hf-4-8-reference-series-hf-subwoofer-4-ohm to join the others in the small sub stable. The goal is 4. All on class D power.
I've been very happy with results from small subs in the past. As little as one single 8" bass reflex sub by Energy. That one changed some of my preconceived sub notions. The esw-8 are capable little guys.
All but the sub mentioned had sealed boxes. I achieve fast punchy articulate bass with 8s. But of course many other factors are at play. The room is 9x13x8 feet.
I should like where my current bass journey takes me.
Works for me! 😉 (4) of these is larger than a prosound 15" (876 cm^2 Vs 856 cm^2), more than required in a small room plus can optimize locations for a more immersive experience.
I had 4 going before, less volume gain was required to achieve similar SPLS. The bass sounded a lot cleaner with nice smooth roll off. Room nodes weren't a problem at all, with one sub. Best with a minimum of two. The last build I was using full range bps Mirage floor speakers that helped fill in bottom end. The psb stand mounts I currently have can be a bit finicky. I should say a lot finicky. The bass exists but it tends to concentrate and be limited to very small areas. Right where I sit at my desk has limited success. Where its always been rock solid in the past. I can hardly wait to see how generating more bass will open things up.
I started to rethink things, I should of perhaps went slower to start granted I had very simple intentions at the start.
Ideally I'd like 2x2, the mix of 8s and 10s. I may. I'll just continue keeping the Rel in place for now. Its not as much woofer but the passive might have it playing catch up with the Daton's. If I try one of those minidsp boxes and other D amp it might work almost as well and get me where I want to go faster. Reason being I just finished paying less than 300 for a second owner late model Crown 2 ch with drive core2. If I could get by with using 2 of them with a dsp box what reason why not? It has a crossover built in but I don't think it will do. So it might be ran in passive mode. I'll have to hear it to conclude.
If someone wouldnt mind comparing those two to confirm It would be appreciated. https://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4-hd
https://www.hypex.nl/product/fusionamp-fa251/155
I wasn't that aware of Dayton stuff, if they sound as good as they look Ill be happy. I like these a bunch https://www.parts-express.com/Dayton-Audio-RSS210HF-4-8-Reference-Series-HF-Subwoofer-4-Ohm-295-456
the 10"
https://www.parts-express.com/Dayton-Audio-RSS265HF-4-10-Reference-Series-HF-Subwoofer-4-Ohm-295-460
The 8's work in tiny little .55 ft coxes @27 hz. If I go with vented I'd only be fitting two total. I haven't checked for a suitable passive radiator if theres one out there. If it would even be needed, I can't say.
Ideally I'd like 2x2, the mix of 8s and 10s. I may. I'll just continue keeping the Rel in place for now. Its not as much woofer but the passive might have it playing catch up with the Daton's. If I try one of those minidsp boxes and other D amp it might work almost as well and get me where I want to go faster. Reason being I just finished paying less than 300 for a second owner late model Crown 2 ch with drive core2. If I could get by with using 2 of them with a dsp box what reason why not? It has a crossover built in but I don't think it will do. So it might be ran in passive mode. I'll have to hear it to conclude.
If someone wouldnt mind comparing those two to confirm It would be appreciated. https://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4-hd
https://www.hypex.nl/product/fusionamp-fa251/155
I wasn't that aware of Dayton stuff, if they sound as good as they look Ill be happy. I like these a bunch https://www.parts-express.com/Dayton-Audio-RSS210HF-4-8-Reference-Series-HF-Subwoofer-4-Ohm-295-456
the 10"
https://www.parts-express.com/Dayton-Audio-RSS265HF-4-10-Reference-Series-HF-Subwoofer-4-Ohm-295-460
The 8's work in tiny little .55 ft coxes @27 hz. If I go with vented I'd only be fitting two total. I haven't checked for a suitable passive radiator if theres one out there. If it would even be needed, I can't say.
Last edited:
Some of us get it but you still might want to look deeper into that. You can keep stacking onto that same idea in a variety of ways NOT only including mechanical vibration advantages or those specific to the driver position terms of each other. That whole concept can go to both sides of the drivers and closed-ends on each as well. And there lies a gold mine. Pretty much seals the deal if you apply what you’re saying with two transmission lines both using the concept Martin King coined at 0349x piie length. But it is a compound qw pipe or higher order number 05238 radians, 05236 if using the number ‘pi’ or if you look at Martin King’s number that was the radius of the sun or seconds in 12 hours(432)^2 as 186624, (186624)^2 as 349……. And you’re at by divided by nine (349065) TL or pi divided by six(52359877) dual closed end qw pipes in sync.
Dave, imagine what that does and then simulate it and compare apples to apples The same driver but move it around on both sides simultaneously or cross them up in tastThe same driver but move it around on both sides simultaneously or cross them up Using random positions on either side and there’s plenty there to checUsing random positions on either side and there’s no missing it was doing it in response using real time where it exposes thankfully the wonderful details . and you’ll see a breaking of it down further and further is doubling the contribution to the bBand with like shooting bird shot instead of one big lead slug or two. What’s the dual ODTL and OD exitsplit up into four rectangles and horn response is given that explanation as all the segments are equal length on both sides..
Attachments
I heard both the small one and the larger Phantom I, in a tiny booth in a high end dept store. The smaller one was fine as a posh bluetooth speaker but the larger one disintegrated acoustically on one track by Britten (#14 here) - the bass simply overloaded.
Two 18 have more Sd than one 21 so do not need as much excursion to move the same volume of air. The Sd of one 21 is close to the Sd of two 15s so I agree that two 18s make more sense than one 21 in every way.
That seems to be par for the course? ‘Acoustics of ducts and mufflers’ -Munjal. Martin King and myself bought this about the same time, maybe it’ll help.
pressure inside the pipe as the 3/4 harmonic(not 1/4) is useful as individual segments as resonators but make them all part of the fundamental. but the fundamental isn’t the entire pipe it’s a three to one (with a turbo). Except this ‘turbo’ has no lag.
If you swing a pendelum by definition of frequency and in one second it Will complete 30° or pi/6, but This is pi/ nine for transmission lines as Martin King documented as 0349. But he didn’t tell the whole story or explain of the source… oh well.
equal and opposite pressure waves are (sine/cosine) coming towards each other from either end Of a compounded qw pipe at all times but from opposite polarity that number 0349 is technically 05236 now, pi/9 vs pi/6. These numbers are radiant and I helped define a breakdown to circle the thThese numbers are radiant and I helped define a breakdown to circle. When you do this you can draw sinewave all the way around the circle 360° and the drivers will be separated by 300° change that to centimeters change that the radiant change that anything you want it doesn’t matter the point is time and flight and also driver has fixed everything and more as pictureWhen you do this you can drive sideways all the way around the circle 360° and the drivers will be separated by 300° change that to centimeters change that the radiant change that anything you want it doesn’t matter the point is time and flight and also driver has fixed everything and more.
Maybe better to look at this response and compare and contrast things to better understand it then be explaining it which fails to deliver it seems.
It’s up to you but meanwhile there’s a superior subwoofer that is not that difficult to build that people might want to be aware of. Knowledge is free but Maybe Thats why it hard to understand? I’m not used to having it??😂
It isn’t That big of a deal once you look in horn response. Martin king was doing the same thing but using a MLTL / bass reflex last I talked to him, But that does not work. it comes up with a phase discontinuity every time.
