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Author Topic: Radian Audio Engineering's 2218 Neo Driver: Absurd Claims or Not?  (Read 16803 times)

Mark ☻Bass Pig☻ Weiss

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After owning a half dozen EVX 180Bs for 9 years, I've done my periodic "let's see what the state of the art is now" lookie-loo and happened across a company called Radian Audio Engineering and their 2218 Neo woofer.


To make things clear, I'm not using these in a subwoofer application, just mid-bass from about 30-130Hz.


I read over the data sheet for it and some things don't add up. Rather, the claims read like a wish list for the magic genie.


Radian has two flavors of 18" driver. One has a big ferrite magnet and rather 'meh' specs, similar to most every pro 18" out there. SPL measured not even in the bass range, but around 400-500Hz, and is down about 30dB by 20Hz.


However, the 2218 neo's SPL is specified at 32Hz, and the response graph is the flattest I've ever seen for any driver. From it's output level at 100Hz (102dB @ 1W), it's output at 20Hz is only down 5dB. They claim 101dB at 1W 1M at 32Hz. Most pro 18's are down around 70dB at that frequency.


In other words, the acoustic power output at 20Hz is about 500 times greater than the ferrite magnet driver of the same size, according to the response graphs calibrated in SPL with 2.83V input. I'm having serious trouble believing that graph!


However, the Qts, Qms and Qes figures are very low, and the Xmax is about 3.3x more than many of the best pro 18" drivers.


The interesting thing is that it's got about 50x as much neodymium magnet mass as anything I've seen on the market from TC Sounds and other companies, which have maybe 6oz of little neo bar magnets inside a pot core. This has two big slabs about 3lbs each, about the size of a ferrite magnet, but neodymium. It's possible that the magnet system could be in the neighborhood of 100,000 gauss with all that neo.


I'm contemplating buying one and testing it against the EVX 180B to see if it's really THAT much better, or if it's BS.


Has anyone had any direct personal experience with this Radian 18" woofer? Not the ferrite version, but the Neo version? Would be interested in hearing your impressions and any measurement data you may have taken.
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Take care,

Mark & Mary Ann Weiss

http://www.MWHDvideo.com
http://www.basspig.com The Bass Pig's Lair
http://www.ampexperts.com

Craig Hamilton

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Re: Radian Audio Engineering's 2218 Neo Driver: Absurd Claims or Not?
« Reply #1 on: April 14, 2015, 12:27:14 am »

Those are some crazy specs. I think the marketing department got ahold of that frequency response chart. I'm still a big fan of the 18 Sound 18NLW9600 that PK sound and Danley uses as well as others. The new RCF LF18X451 has some impressive specs as well.
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Mark ☻Bass Pig☻ Weiss

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Re: Radian Audio Engineering's 2218 Neo Driver: Absurd Claims or Not?
« Reply #2 on: April 14, 2015, 03:40:15 am »

Those are some crazy specs. I think the marketing department got ahold of that frequency response chart. I'm still a big fan of the 18 Sound 18NLW9600 that PK sound and Danley uses as well as others. The new RCF LF18X451 has some impressive specs as well.


Yeah, very hard to believe. I put a call into Radian, but the engineering people had already left for the day, so they're instructed to call me back the next day.


To their credit, the non-neo version has very down to earth specs, so if they are using the same yard stick to measure both, then the neo is SOME driver.


I also contacted one of the sellers of this driver, US Speaker, who answered and said that the claims are accurate.


At any rate, I hope to have a lively conversation with the engineering people this week. If I get the right kinds of answers, I'll invest the $800 or so and try one of them, with a direct comparison of sweeps and SPL at various power levels, to the EVX180B. If it's all good, then I'll have six 180Bs for sale on eBay soon. :)
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Take care,

Mark & Mary Ann Weiss

http://www.MWHDvideo.com
http://www.basspig.com The Bass Pig's Lair
http://www.ampexperts.com

Scott Carneval

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Re: Radian Audio Engineering's 2218 Neo Driver: Absurd Claims or Not?
« Reply #3 on: April 14, 2015, 10:10:14 am »


To make things clear, I'm not using these in a subwoofer application, just mid-bass from about 30-130Hz.


You have an interesting perspective on the definition of a subwoofer haha.  To be clear, I like my bass just as much as the next guy, but you're implying that your 'subwoofer' is a sub-30hz cabinet? 
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Steve Bradbury

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Re: Radian Audio Engineering's 2218 Neo Driver: Absurd Claims or Not?
« Reply #4 on: April 14, 2015, 12:16:17 pm »

The calculated sensitivity figures come out less than the 101dB @ 32Hz



The green plot is for a cabinet of 243ltr tuned to 32Hz as recommended in the data. The blue curve is for a 120ltr tuned to 45Hz. The red is a comparison of two 12" Ciare1200W drivers in an 80ltr cabinet tuned to 46Hz. The latter is a design I have real measurements for.


The next image shows the calculated max spl.



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Mark ☻Bass Pig☻ Weiss

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Re: Radian Audio Engineering's 2218 Neo Driver: Absurd Claims or Not?
« Reply #5 on: April 14, 2015, 05:02:46 pm »

The calculated sensitivity figures come out less than the 101dB @ 32Hz



Those charts are a lot more believable.


I just got off the phone with Mark at Radian Audio. I had a hard time getting specific answers to questions, but I did ferret out that the max travel ability of the cone is in excess of 4", because earlier suspension designs self-destructed with that magnet. There are two 4" rings of neo. They use a "6 grade" neo that is stable to 365°.


When they initially got the neo material, their vendor that charges the magnets told them that they didn't have a coil with enough joules to charge that magnet to full flux. They spent $28K on a new coil to accomplish this. They don't know what the flux density is, because it pegs their meter whose max range is 20,000 gauss.


They got the response curve in a carefully-tuned ported box. A customer of theirs is using a pair in a cinema setup driven with 4,000W amplifiers. He emphasized that 4000 watts was fully dedicated to each 2218 neo driver, and no failures.


He also said that Bassmaxx is using them or has been testing a few of their product and liked them better than B&C, Ciare, and a bunch of others.
In the unusual applications field, the US gov bought a bunch of them to use in a LF noise mitigation project on an aircraft carrier.


When I told him I was planning to buy one to evaluate, he offered to send me one unit free of charge to evaluate and put through the paces. In earlier communication, I had given him links to my sound system and audio repair business sites, so he had some idea of whom he was dealing with. Even so, he seemed unafraid to have me evaluate their product on his dime. So I sent the request in after we finished the phone call, which lasted about 45 mins.




My definition of 'bass' differs a good bit from the norm. I live in the world of 64' organ pedal stops (8Hz), pyrotechnics and LF synthesizer bass. Much of the bass in J-pop and K-pop music is below 20Hz nowadays. Not just the spectral hash from a kick drum, but the fundamental bass notes in the music. The opening logo for the recent film, Live, Die, Repeat goes down to the single digits and is reported to make most theater subs flap. What flapped over here was the acoustic transparent screen. It flapped so hard, you could see it move, even on axis. The duration was only a few seconds, but it rearranged all the furniture upstairs. Much of the bass in the music I listen to lives below 20Hz. For decades, that meant the opening organ pedal tone to Richard Strauss' 'Also Sprach Zarathustra', but since the late 1990s, I've been seeing an influx of 'subsonic' bass in music from Japan.


I'm somewhat optimistic about what Radian brings to the table here. If they do send an evaluation unit, then I will run a sequence of tests and, if they go well, will install it in the system and listen further.
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Take care,

Mark & Mary Ann Weiss

http://www.MWHDvideo.com
http://www.basspig.com The Bass Pig's Lair
http://www.ampexperts.com

John Roberts {JR}

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Re: Radian Audio Engineering's 2218 Neo Driver: Absurd Claims or Not?
« Reply #6 on: April 14, 2015, 06:03:51 pm »

don't hurt those little guys,,,,  :-)

JR
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Mark ☻Bass Pig☻ Weiss

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Re: Radian Audio Engineering's 2218 Neo Driver: Absurd Claims or Not?
« Reply #7 on: April 14, 2015, 07:30:10 pm »




The green plot is for a cabinet of 243ltr tuned to 32Hz as recommended in the data. The blue curve is for a 120ltr tuned to 45Hz. The red is a comparison of two 12" Ciare1200W drivers in an 80ltr cabinet tuned to 46Hz. The latter is a design I have real measurements for.


The next image shows the calculated max spl.





Just for kicks, what results to you get when you model an EVX180B? My data sheet for the EXV 180B shows a max SPL of 89dB @ 20Hz and 110dB @ 100Hz.
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Take care,

Mark & Mary Ann Weiss

http://www.MWHDvideo.com
http://www.basspig.com The Bass Pig's Lair
http://www.ampexperts.com

Steve Bradbury

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Re: Radian Audio Engineering's 2218 Neo Driver: Absurd Claims or Not?
« Reply #8 on: April 16, 2015, 06:10:55 am »

Before continuing I should mention my disclaimer. Computer models generally give approximately close results to those measured. Errors in the data used can ruin the results. Neither manufacturers nor myself are immune to typos and other mistakes.  None of the results look untoward, but feel free to challenge or question them.

Here is a plot comparing the EV with the Radian. EV is the green plot in a cabinet I figured would work well. The Radian is the manufacturer’s recommended cab.



Concerning the 101dB sensitivity figure: In a large enclosure it is possible to get a peak in response that gets there. See the green plot below. This is not a cabinet I would recommend.



The blue plot is the response in a large sealed enclosure. The interesting thing about this is if you consider the true efficiency of the loudspeaker. Usually plots are calculated using the required voltage to produce 1W into the DC resistance of the coil. This is the nominal efficiency.

The sealed cabinet has an impedance peak of about 68 ohms at 30Hz (2.3V squared / 68 does not equal 1). If you add suitable eq to bring the true power back up to 1W the response is as shown below.



Looking at the true efficiency raises some interesting design ideas which go against conventional wisdom. It is going off topic somewhat and I don’t have time to discuss the subject at the moment. If anyone is interested I can continue later or start another thread.
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Josh Ricci

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Re: Radian Audio Engineering's 2218 Neo Driver: Absurd Claims or Not?
« Reply #9 on: April 16, 2015, 11:25:25 am »

Someone brought this driver up in another forum a while back. Frankly I see a number of red flags in the spec sheet. Firstly the xmax rating. This is what everyone seems to gush over with this driver. They give no reference as to what this is based on, whether a gap geometry calculation, Klippel measurement, or based on a distortion threshold in free air. They give no gap or coil measurements  at all.

The xmax rating is about 1/3rd greater to 2x the current crop of professional woofers excepting for a few highly engineered products at the top of the food chain. Now consider the weight of this driver. 17.15lbs. Any of the other neo motor pro woofers with legitimate one way xmax in the >13mm range weigh 2 to 3x as much.

What is the depth of this driver? 7.88" overall. Much shallower than the comparable high excursion woofers. Just look at the pictures available of the woofer. If you know enough about driver design you know some of the clearances involved to allow that much excursion in a linear manner. The depth of the driver and the spacing of the spider from the top plate and overall depth of the motor indicate that that much one way travel is highly unlikely from a mechanical clearance and gap geometry perspective. High xmax means a longer wind and a taller gap or both. Both of which increase overall motor depth and/or reduce the rearward coil clearance. If it is capable of moving that far then the Xmech follows very shortly thereafter judging from the data we have. Xmech is not rated on this driver either. No way in hell will this do 4" peak to peak mechanically. That IS an absurd claim. 18" drivers that really can move their cone assembly that far are 13-16" deep. They must be to provide the clearances and gap geometry needed.

Also the SD is greatly exaggerated in my estimation. It is much more than a standard 18" driver on the sheet but the outer frame size is normal if not a bit undersized compared to most. And the response graph is very heavily smoothed.

Just applying a bit of logic says that if it claims to be: Half the weight, twice the xmax, 2/3rd's the depth and +17% cone area from the same frame size compared to the rest of the market, it probably isn't true. The xmax is almost assuredly a peak to peak rating, or possibly an xmech rating.

All that said it may very well be a great driver still just with a very exaggerated xmax and SD. I could be completely wrong altogether and have to eat crow too, but I don't think so. Perhaps I'll see if Radian will loan me one for the test bench.
« Last Edit: April 16, 2015, 11:28:50 am by Josh Ricci »
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Re: Radian Audio Engineering's 2218 Neo Driver: Absurd Claims or Not?
« Reply #9 on: April 16, 2015, 11:25:25 am »


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