Anyone try the QSC HPR152i waveguide w/Radian 475 Be CD? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 50 Old 01-22-2017, 12:26 PM - Thread Starter
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Anyone try the QSC HPR152i waveguide w/Radian 475 Be CD?

Do you think the QSC HPR152i waveguide would be a good match to the Radian 475BePB beryllium CD?

I was looking to try a Be driver. I have the QSC 152 WG and a Seos 15 WG and was looking to use one of the 2 with the 475BePB. I had heard others report that the non-Be CD's from radian worked well on the QSC.

Feel free to speculate
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post #2 of 50 Old 01-22-2017, 12:39 PM
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Just speculation here, I'm afraid. I've never tried that particular driver, but I don't see any reason it shouldn't work well on a SEOS or 152i. Both are really nice waveguides and that is supposed to be a really good driver of the right throat size.

I don't know the throat angle of that driver though. I've had wide throat drivers (like Celestions 1445) on the 152i and they worked really well. Also, the short-throat (so wide angle, I assume) Tymphany compression driver works very nicely on both those waveguides -- even though the SEOS was designed around the narrower angle throat DE250.

If you already have the driver, getting a good clone of the 152i waveguide to try with it is almost free at the moment (http://www.parts-express.com/prv-aud...bolt--294-2892, $10). The clone seems a little better made than the original, even, and original was no slouch.

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post #3 of 50 Old 01-22-2017, 07:55 PM
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I was wondering about the throat angle also. I think someone posted the angle for the radian 475 somewhere in the big seos thread.

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post #4 of 50 Old 01-22-2017, 08:52 PM - Thread Starter
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I e-mailed Radian for the info. I'll post when/if they respond. Others got responses from them on other such questions. It's likely to work well with one of the 2 wave guides I have. One is proven with CD's with 14 deg exit angles, the QSC works well with CD's in the 20 range.
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post #5 of 50 Old 01-22-2017, 11:40 PM
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I'm slightly curious about evaluating the Radian 475 Be on an SEOS-15 horn. I'm using DNA-360s right now, and they really are wonderful drivers up to 15 kHz or so. Above there, things get a bit weird due to break-up, as is the most drivers.

Still, I'm a bit concerned about how low it can actually play, and the fact that it uses Be in the diaphragm is no guarantee that it is capable of extending higher without break-up. The DNA-360 can play remarkably low without distortion rising much, sufficient for a 950 Hz XO in my case. Also, the Radian Be driver is just a bit expensive if I buy one and decide not to use it.

To the credit of the DNA-360, my measurements suggest it is quite stable and linear within the break-up region until fairly extreme output levels. As such, I can EQ out most of the worst aspects of the break-up at the cost of somewhat narrower dispersion through the 16-18 kHz region that can't be fixed by EQ. I haven't tried boosting it all the way to 20 kHz, but am hitting 19 kHz no problem.

Still, I have to say that I wish there were more/better measurements of high frequency drivers available. It's rare to see even an impedance plot from a manufacturer much less power compression or distortion measurements at multiple output levels. Without hard data, it's hard to know whether a particular Be phgram is actually better than a particular polymer phragm in a particular application, despite the theoretical advantages of the former material. Engineering details impact performance, and without measurements, there is no proof of real world performance.
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post #6 of 50 Old 04-17-2017, 09:05 PM - Thread Starter
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Updating the thread, I finally received the Radian 475 Be drivers today after what seemed like forever with the back order. I have both the QSC 152 and SEOS 15 WG's. I connected the CD's momentarily to verify that they were not DOA.

Now for testing, I received the Umik/calibration files and I downloaded REW. Anyone local to Colorado Springs wish to help/teach me test?
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post #7 of 50 Old 04-17-2017, 09:13 PM - Thread Starter
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Originally Posted by awediophile View Post
I'm slightly curious about evaluating the Radian 475 Be on an SEOS-15 horn. I'm using DNA-360s right now, and they really are wonderful drivers up to 15 kHz or so. Above there, things get a bit weird due to break-up, as is the most drivers.

Still, I'm a bit concerned about how low it can actually play, and the fact that it uses Be in the diaphragm is no guarantee that it is capable of extending higher without break-up. The DNA-360 can play remarkably low without distortion rising much, sufficient for a 950 Hz XO in my case. Also, the Radian Be driver is just a bit expensive if I buy one and decide not to use it.

To the credit of the DNA-360, my measurements suggest it is quite stable and linear within the break-up region until fairly extreme output levels. As such, I can EQ out most of the worst aspects of the break-up at the cost of somewhat narrower dispersion through the 16-18 kHz region that can't be fixed by EQ. I haven't tried boosting it all the way to 20 kHz, but am hitting 19 kHz no problem.

Still, I have to say that I wish there were more/better measurements of high frequency drivers available. It's rare to see even an impedance plot from a manufacturer much less power compression or distortion measurements at multiple output levels. Without hard data, it's hard to know whether a particular Be phgram is actually better than a particular polymer phragm in a particular application, despite the theoretical advantages of the former material. Engineering details impact performance, and without measurements, there is no proof of real world performance.
These drivers source diaphragms from truextent as do many other great sounding CD's. I'm not sure why you suspect these would not sound good without evidence from factual cases. Other models from Radian using Be diaphragms are well received.
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post #8 of 50 Old 04-18-2017, 02:25 AM
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Originally Posted by SpinMonster View Post
These drivers source diaphragms from truextent as do many other great sounding CD's. I'm not sure why you suspect these would not sound good without evidence from factual cases. Other models from Radian using Be diaphragms are well received.
I have heard great things about the 475BePB. Will you be using it in a 2 way application crossed low to what woofer? I must admit that 1" exit Be diaphragmed compression drivers never really interested me. If I am going to spend that kind of money on a compression driver then I am going for the Radian 951BePB crossed to an AE TD15 or similar quality woofer. If what I read is true, the biggest advantage of having Be diaphragms are extending the breakup modes in the top end of the compression drivers response, which is more advantageous and more helpful on a 1.5"-2" exit compression driver such as the 951BePB, the 950BePB, the JBL 2453, 2446, 2447 etc.
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post #9 of 50 Old 04-18-2017, 05:49 AM - Thread Starter
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Originally Posted by Tip24/96 View Post
I have heard great things about the 475BePB. Will you be using it in a 2 way application crossed low to what woofer? I must admit that 1" exit Be diaphragmed compression drivers never really interested me. If I am going to spend that kind of money on a compression driver then I am going for the Radian 951BePB crossed to an AE TD15 or similar quality woofer. If what I read is true, the biggest advantage of having Be diaphragms are extending the breakup modes in the top end of the compression drivers response, which is more advantageous and more helpful on a 1.5"-2" exit compression driver such as the 951BePB, the 950BePB, the JBL 2453, 2446, 2447 etc.
Respectfully, the biggest advantage of Be drivers is the SQ up top with bell sounds being clean and lacking the etched/rougher sound of typical poly diaphragms. I can attest that the sound of the top end is silky compared to the BMS 4550 driver it replaced. I know that few people care about subjective evaluations but for me, that alone was worth the price of admission.

Staying with measurements, waterfall decay tells the whole story there. Be is clean with little ringing. There is no fall off in freq above 15k and the break up is not audible if it is there.

My theater has a more extreme build. This system is a cheap compromise that is keeping me out of divorce court. I can't have a 26" wide system in my living room because the wife isn't going to have it. End of story. If someone is looking for a 1" driver for a SEOS 10 or 12, this is a driver that should be explored. Even Dr. Geddes noted the BE sound to be better than his B&C choice but stayed with the $ constraint. I don't have that limit.

As far as cost, this driver was $549 (now it's 599). The 951Be is $1249 each. It's not so close as to suggest that the 475 wasn't a good buy or that I should have bought the 951 due to 'spending that kind of money'. You have to stop somewhere. I'm trying to explore/discuss this driver without everyone talking about their dream system that is twice the size and cost of what is allowed in the real world with a wife that has a huge vote.

For those limited to the 1" CD size, can we please simply discuss the 475?
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post #10 of 50 Old 04-18-2017, 07:14 AM
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I've heard great compression drivers sound just average when they don't match the horn. Do you know what the exit angle of the Radian is?
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post #11 of 50 Old 04-18-2017, 09:18 AM - Thread Starter
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I've heard great compression drivers sound just average when they don't match the horn. Do you know what the exit angle of the Radian is?
As I stated earlier in the thread, I e-mailed radian but they didn't respond to the question......twice.

Radian CD's (Non-Be) have been used on SEOS WG's with positive results. Regardless, I bought these two WG's and will hopefully put the conjecture to rest about their performance with them.

Bill Waslo addressed the results of wide and narrow angle drivers on these two WG's above

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post #12 of 50 Old 04-18-2017, 09:22 AM - Thread Starter
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BTW, my two BMS 4550 CD's are for sale. $200/pair shipped US 48 only.
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post #13 of 50 Old 04-18-2017, 09:34 AM - Thread Starter
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Originally Posted by awediophile View Post

Still, I'm a bit concerned about how low it can actually play, and the fact that it uses Be in the diaphragm is no guarantee that it is capable of extending higher without break-up.

Without hard data, it's hard to know whether a particular Be phgram is actually better than a particular polymer phragm in a particular application, despite the theoretical advantages of the former material. Engineering details impact performance, and without measurements, there is no proof of real world performance.
Have you ever seen a valid test showing Be to not outperform? Without hard data it is not realistic to assume Be is outperformed by conventional diaphragms.
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post #14 of 50 Old 04-18-2017, 12:52 PM
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fwiw the non Be version is measured on a SEOS18 in this post, be interesting to see how your measurements compare
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post #15 of 50 Old 04-18-2017, 01:25 PM - Thread Starter
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fwiw the non Be version is measured on a SEOS18 in this post, be interesting to see how your measurements compare
Thanks, I had seen that post a while back.

Be diaphragms tend to be smoother than poly/titanium. I think it was NOTNYT that posted something as evidence. I think the DE250, 360, and 4550 looked more similar than different in the curves. In the end it comes down to if you think Be is worth the difference in performance. I think everyone has their own constraints. Saying one curve is smoother than another or that this driver has a peak here or there, is an issue of EQ. For me, ringing out of the pass band and evidence of better SQ up top is mounting for Be drivers. I can tell you first hand that the BMS4550 and the Radian Be do not sound the same after EQ. I'm trying to avoid subjective impressions but I can tell you bell type sounds, cymbals, and highs in general aren't fuzzy sounding on the Radian. The BMS is a great driver and I enjoyed it but I'm loving the upgrade.
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post #16 of 50 Old 04-18-2017, 05:37 PM
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Please post some measurements if at all possible. Id love to see them

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post #17 of 50 Old 04-18-2017, 05:59 PM
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Originally Posted by SpinMonster View Post
Have you ever seen a valid test showing Be to not outperform? Without hard data it is not realistic to assume Be is outperformed by conventional diaphragms.
I'm not assuming anything. I'm just skeptical that just because a tweeter or CD uses Be means that it will outperform alternatives. The ultimate performance depends on that of the system as a whole. That includes the voice coil, the surround materials and geometry, the overall build quality, the type of horn its mated with and the quality of that mating, and any crossover or DSP that is applied to clean up the response. This last point cannot be overemphasized. Many resonances and other unwanted behavior can be substantially reduced or even eliminated with skillful application of DSP.

However, DSP can't cure every problem. So a driver that performs relatively well in a passive system may not perform as well in an active system with optimized DSP and vise versa. The fact is, however, that there is nowhere near enough data available for various CD and horn combinations to make these kinds of judgments. Certainly this is the case with the Radian Be models. Even though the Be diaphragm is likely to exhibit break-up at a higher frequency than a diaphragm made from a different material, the CD may have other resonances that are still problematic. And of course, if you read my original post, you'll note my desire to use a lower XO frequency. The Radian Be drivers are likely to struggle with this requirement as well.
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post #18 of 50 Old 04-18-2017, 08:09 PM - Thread Starter
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Originally Posted by awediophile View Post
I'm not assuming anything. I'm just skeptical that just because a tweeter or CD uses Be means that it will outperform alternatives. The ultimate performance depends on that of the system as a whole. That includes the voice coil, the surround materials and geometry, the overall build quality, the type of horn its mated with and the quality of that mating, and any crossover or DSP that is applied to clean up the response. This last point cannot be overemphasized. Many resonances and other unwanted behavior can be substantially reduced or even eliminated with skillful application of DSP.

However, DSP can't cure every problem. So a driver that performs relatively well in a passive system may not perform as well in an active system with optimized DSP and vise versa. The fact is, however, that there is nowhere near enough data available for various CD and horn combinations to make these kinds of judgments. Certainly this is the case with the Radian Be models. Even though the Be diaphragm is likely to exhibit break-up at a higher frequency than a diaphragm made from a different material, the CD may have other resonances that are still problematic. And of course, if you read my original post, you'll note my desire to use a lower XO frequency. The Radian Be drivers are likely to struggle with this requirement as well.
Your concerns are valid but they apply to any driver put on the wrong WG/horn or implemented wrong. It isn't reserved for Be CD's. My point is a statistical one. I have never seen a Be driver not outperform, TAD, Truextent JBL outfitted drivers, or just plain tweeters. You state a driver may still break up so low as to not get a benefit from the material....I've never seen it. Sticking to statistic proven facts, Be hasn't been shown to be a detriment.

Be drivers used really low are common with bigger 2" drivers (NotNyt). The improved high end response allows for EQ to make up for the early roll off. 2" JBL drivers prove this every day. Be drivers from radian use a polymer surround which negates the strain at lower frequencies in comparison to other CD's of the same size. Used above 800hz, the 475 is fine. Expecting a 1.75" diaphragm to go lower is a design blunder. If you want to go lower on a 24" Seos, the 951 Be from Radian is used that way all the time but it's a bigger diaphragm with a 1.4 exit. A simple search shows your concern isn't really true since the combo is used all the time to 500hz. If you want to go lower than that then keep in mind you are on a thread talking about a 1" exit CD.

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post #19 of 50 Old 04-18-2017, 08:26 PM - Thread Starter
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Please post some measurements if at all possible. Id love to see them
I wish we lived close to each other to facilitate that.
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post #20 of 50 Old 04-19-2017, 02:25 AM
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Your concerns are valid but they apply to any driver put on the wrong WG/horn or implemented wrong. It isn't reserved for Be CD's. My point is a statistical one. I have never seen a Be driver not outperform, TAD, Truextent JBL outfitted drivers, or just plain tweeters. You state a driver may still break up so low as to not get a benefit from the material....I've never seen it. Sticking to statistic proven facts, Be hasn't been shown to be a detriment.

Be drivers used really low are common with bigger 2" drivers (NotNyt). The improved high end response allows for EQ to make up for the early roll off. 2" JBL drivers prove this every day. Be drivers from radian use a polymer surround which negates the strain at lower frequencies in comparison to other CD's of the same size. Used above 800hz, the 475 is fine. Expecting a 1.75" diaphragm to go lower is a design blunder. If you want to go lower on a 24" Seos, the 951 Be from Radian is used that way all the time but it's a bigger diaphragm with a 1.4 exit. A simple search shows your concern isn't really true since the combo is used all the time to 500hz. If you want to go lower than that then keep in mind you are on a thread talking about a 1" exit CD.
Nor are Be CDs exempt from problems caused by either poor implementation or poor system design. That's all I'm saying. I simply don't have enough data about the Radian 475Be or even the regular 475 in an SEOS horn. What anecdotal information I have found (for the 475 only) is not especially encouraging.

If I recall right, there is big exit angle mismatch. This could kill most of the benefit of having a higher frequency first break-up mode. Second, I read at least one anecdotal report in which it was claimed to not sound good in an SEOS horn without a XO well above 1kHz.

While Radian claims 800 Hz as a low point for the 475, it's minimum XO point on an SEOS horn is likely to be quite a bit higher than this. This would be consistent with other available CDs. Manufacturers usually measure using a horn with a lot more loading than the SEOS provides.

For these reasons along with its high cost, I opted to pass on the driver for my initial build. Instead, I evaluated the DNA-360 along with another driver that I can't name here at this moment. The other driver had a cleaner and much more sensitive top end, but I chose the DNA-360 because it handled lower frequencies much better.

I'm now pushing my DNA-360s more or less flat to 20 kHz now. They seem to handle it just fine, even though it requires a huge amount of boost. The level of real world content is very low up at the very top. In any case, I definitely notice the extra extension. Even though the DNA-360s break-up at 15-18 kHz, my DSP correction eliminates most of the ringing. The aberration in the dispersion pattern remains, but I have a hard time telling if I can hear it or not. The sound, even the very highest of frequencies, doesn't seem to change noticeably when moving off-axis. I have diffusion in my room, which may help a lot with this.

Anyway, I won't judge the 475Be in SEOS until I see the measurements, and even if it doesn't work well in the SEOS, it could work fine in the QSC.

On the subject of measurements, I did measurements of the DNA-360 in an SEOS-15 horn, which are posted here. I really should create a thread for them here at AVSForum too. I have to point out that you probably won't find more extensive measurements for a CD + horn combo anywhere else. I'm not trying to brag either. IMO, this is the kind of data required to really understand potential performance.

Do you have any plan or idea of what you want to measure?
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post #21 of 50 Old 04-19-2017, 08:53 AM - Thread Starter
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Originally Posted by awediophile View Post
What anecdotal information I have found (for the 475 only) is not especially encouraging.

If I recall right, there is big exit angle mismatch. This could kill most of the benefit of having a higher frequency first break-up mode. Second, I read at least one anecdotal report in which it was claimed to not sound good in an SEOS horn without a XO well above 1kHz.

While Radian claims 800 Hz as a low point for the 475, it's minimum XO point on an SEOS horn is likely to be quite a bit higher than this. This would be consistent with other available CDs. Manufacturers usually measure using a horn with a lot more loading than the SEOS provides.

Do you have any plan or idea of what you want to measure?
Here's the Radian 475, B&C DE250 and the BMS 4550 on the SEOS 18. The Radian looks fine on the bottom end to the limits of the SEOS18. If you want to extend under 800hz then you should be looking at the 951 Radian and EQ for the top. Be extends farther up on its own without EQ. Since many on here are EQ'ing the top end of 2" exit truextent diaphram CD's to be flat without break-up, the 1.4" 951 will not have an issue. Regardless the 475 extends fine to 800hz. No Truextent BE diaphragm has low extension problems so I do not know where you are getting that info from.



Everything I found about the Radian drivers shows them as excellent performing. John from AE loves the 475 and uses it with the SEOS 15.

Bill Waslo stated in post #2 to have used both narrow and wide exit angle drivers on the two wave guides I have. One of the two wave guides will be fine with the Radian 475. I have found numerous praising threads for the aluminum diaphragm 475.

You seem to assume that there is a mismatch of exit angle on the 475 to SEOS. I fail to see how you determined that there is a mismatch if we do not know the exit angle on any of the radian CD's

This thread is examining the use of the 475 Be on a 15" wave guide to be crossed around 1000 or so to an AE TD12". That's my application. If I was looking for better control to a lower frequency, I would use the 951 Be. I think you need to listen to a Be CD driver to see what the best part of Be diaphragms are. Everyone I've seen who switched to Be says they sound better.

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post #22 of 50 Old 04-19-2017, 09:26 AM
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Im a Be convert for sure. I did a bunch of work with the JBL2446 and Be phragms a little over a year ago and was amazed. But I think you are misunderstanding what awediophile is saying. That graph does clearly show the 475 has less low end capability. Well, that could be debated. But it has about 4-5db less output at 800hz. And yes, output at 800hz matters when crossing at 1000hz. It also has a less smooth response. Hopefully the Be can correct for that. Also the comment about exit angle isnt that its a mismatch, its that we dont know what it is. The fact the Radian wont say and doesnt produce good data is generally a very bad sign. On these forums we all frown on driver manufacturers who dont produce good data. The Radian is clearly in that field. Thats all Im reading from Awediophile's posts. I havent seen much about the 475 to get me excited either. John from AE hasnt produced any data that Im aware of.

I do hope the driver is great. I have a project for it. But wasnt willing to roll the dice on it. So please share what you can

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post #23 of 50 Old 04-19-2017, 11:54 AM - Thread Starter
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Im a Be convert for sure. I did a bunch of work with the JBL2446 and Be phragms a little over a year ago and was amazed. But I think you are misunderstanding what awediophile is saying. That graph does clearly show the 475 has less low end capability. Well, that could be debated. But it has about 4-5db less output at 800hz. And yes, output at 800hz matters when crossing at 1000hz. It also has a less smooth response. Hopefully the Be can correct for that. Also the comment about exit angle isnt that its a mismatch, its that we dont know what it is. The fact the Radian wont say and doesnt produce good data is generally a very bad sign. On these forums we all frown on driver manufacturers who dont produce good data. The Radian is clearly in that field. Thats all Im reading from Awediophile's posts. I havent seen much about the 475 to get me excited either. John from AE hasnt produced any data that Im aware of.

I do hope the driver is great. I have a project for it. But wasnt willing to roll the dice on it. So please share what you can
The Radian has more output at 400hz so I think its an EQ issue and not a limitation at 800hz. It's likely a WG interaction.

I read his posts as pessimistic before any data has been produced. The Be version has zero data available and he is talking about it likely being low end limited based on the aluminum version and he mentioned possible break ups before 20k. It's all conjecture. The aluminum version has zero in common with the tru-extent diaphragms. Maybe it's best to save fears/comments until we see facts. We will not be squashing anyone's opinions. I value his too.

I have 2 wave guides that are both optimized for different exit angles so my point was one of the two is likely a great match. I have the driver and won't give it up based on how it is working at this time. I will also never use a non-Be driver again. The 4550 and the 250 have a hashy top end quality in comparison. I suspect the 360 to sound the same as the 250 B&C

If you wish to do testing of your own, I will buy another driver and send it to you in the name of helping others out. It's likely all testing I do will be questioned and dismissed anyway. Do you have wave guides to use for testing?

Last edited by SpinMonster; 04-19-2017 at 11:59 AM.
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post #24 of 50 Old 04-19-2017, 01:21 PM
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I do have waveguides but I live in Canada. I have some testing around here of the Be phragms I tested and a youtube video of me talking about the subjective results. It may be interesting to you.

The low end will be exactly the same as the Al phragm as that is dominated by the CD body/chamber. The phragm material will impact things above 4khz or so. They are all 1.75" phragms so theoritically the low end will be the same in all of them. Especially if going active. If going passive, the other two do look better.

My youtube channel: Impulse Audio
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post #25 of 50 Old 04-19-2017, 01:32 PM - Thread Starter
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Quote:
Originally Posted by tuxedocivic View Post
I do have waveguides but I live in Canada. I have some testing around here of the Be phragms I tested and a youtube video of me talking about the subjective results. It may be interesting to you.

The low end will be exactly the same as the Al phragm as that is dominated by the CD body/chamber. The phragm material will impact things above 4khz or so. They are all 1.75" phragms so theoritically the low end will be the same in all of them. Especially if going active. If going passive, the other two do look better.
Link for the youtube vid?

My build is active
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post #26 of 50 Old 04-19-2017, 01:47 PM
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Im on my phone. Search youtube for iwata 300 or something. Big red iwata horns. I have the measurements in a thread started by kingpin. The speaker design was for him.

My youtube channel: Impulse Audio
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post #27 of 50 Old 04-19-2017, 01:50 PM
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post #28 of 50 Old 04-19-2017, 01:53 PM
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Quote:
Originally Posted by SpinMonster View Post
Here's the Radian 475, B&C DE250 and the BMS 4550 on the SEOS 18. The Radian looks fine on the bottom end to the limits of the SEOS18.
--- cut ---
I disagree in this instance. Depending on how you interpret the data, the 475 is -7 dB @ 800 Hz, and its distortion is higher than the other drivers being compared at around -7 dB (44%) THD for a ~90 dB SPL @ 2m sweep. In fact, I'd say none of those drivers are suitable for use anywhere near 800 Hz, going by that data alone.

However given data from other sources, I suspect something weird happened when that data was normalized. The same author posted measurements for the DNA-360 in post 168 of the same thread. The distortion there looks much better for both the DNA-360 and BMS 4550, but unfortunately the sweep level was not recorded even though the author says it was "loud".

If you look at my data for the DNA-360, you'll see that I get about -32 dB (2.5%( THD at 800 Hz for a ~98 dB SPL sweep done at 10 feet. I did not upload distortion data for lower level sweeps, but it diminishes substantially for lower sweep levels. Still, I can actually hear the distortion in the lower frequencies during sine sweeps of the DNA-360 alone at a modest 75 dB SPL at the MLP. I don't hear it with the 950 Hz XO in place though.

Another potential concern is that the 475's response decicted there is messier above 5 kHz than the other drivers measured. In the author's own words: "The Radian 475 does have lower distortion above 1 kHz than the other two drivers. But the lack of smoothness and bottom end means the Radian is out." IMO, the raggedness up top is not a show stopper when using DSP rather than relying on a passive XO, but I would absolutely want to see polar plots to verify that those resonances are consistent across listening position.

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Originally Posted by SpinMonster View Post
No Truextent BE diaphragm has low extension problems so I do not know where you are getting that info from.
This doesn't make any sense. Low end extension has far more to do with the design of the coil and suspension than the diaphragm.

I don't know why you are responding as though I'm biased against Truextent Be diaphragms or Be diaphragms in general. I'm not. I'm just concerned with the performance of the whole package.

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Originally Posted by SpinMonster View Post
Everything I found about the Radian drivers shows them as excellent performing. John from AE loves the 475 and uses it with the SEOS 15.
Do you have a source for this claim that John "loves the 475"? The only info I can find is this post, but I purposely did not cite this before because it's second hand info.

Quote:
Originally Posted by SpinMonster View Post
Bill Waslo stated in post #2 to have used both narrow and wide exit angle drivers on the two wave guides I have. One of the two wave guides will be fine with the Radian 475. I have found numerous praising threads for the aluminum diaphragm 475.
I too have found many threads praising the 475, but I haven't found much positive feedback about the 475 in the SEOS horn. That doesn't mean that it doesn't work well. It just means that its performance is as yet unproven.

The QSC horn is a different story and one that I haven't researched nearly as thoroughly as the SEOS. Even if the 475 and 475Be performs poorly on the SEOS, it may perform very well on the QSC.

Quote:
Originally Posted by SpinMonster View Post
You seem to assume that there is a mismatch of exit angle on the 475 to SEOS. I fail to see how you determined that there is a mismatch if we do not know the exit angle on any of the radian CD's
I don't know. I am only going by what I've learned from combing through a multitude of posts on this forum. In reality, I care about the performance of the end product more than anything, but without measurements I know next to nothing.

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Originally Posted by SpinMonster View Post
This thread is examining the use of the 475 Be on a 15" wave guide to be crossed around 1000 or so to an AE TD12". That's my application. If I was looking for better control to a lower frequency, I would use the 951 Be.
And to quote another snippet of anecdotal information: "When I tried 475PB it in a SEOS15 setup with XO below 1400Hz I experienced an increasingly stronger sibilant distortion as the XO-frequency was lowered. I simply could not use it with the SEOS15. With DE250 I have never experienced this behaviour.
For the two setups I used linear phase FIR filter with steep crossover slopes. [...] Due to my experimence I have therefore been very reluctant to recommend the 475PB unless crossed over 1500Hz+... IMO it then sounds better than the DE250."

Again, this is anecdotal, and it's possible this user had something else wrong in their setup. A sibilant type distortion would not involve distortion of frequencies below 1500 Hz, but it's very possible that high excursions below 1500 Hz may induce intramodular distortion of higher frequencies that are simultaneously present. Depending on the underlying cause, this IMD may also fail to appear in sine sweep THD measurements, which largely fail to reveal non-linear inductance effects.

Quote:
Originally Posted by SpinMonster View Post
I think you need to listen to a Be CD driver to see what the best part of Be diaphragms are. Everyone I've seen who switched to Be says they sound better.
And lots of people claim that metal (non Be) diaphragms offer more detail at the expensive of harshness while polymer diaphragms sacrifice detail for smoothness. This is all hand-wavy and has little bearing on reality in my experience.

Instead, I believe that the primary factor in the sound of a CD + horn combo is its frequency response, both on and off axis. Where polar response is inconsistent as is the case with break-up, aiming for a roughly flat spatial average seems to work better than flat at the MLP. It's as though the ears can hear the sound in multiple room locations at once. This is probably due to the brain's knack for using information from early reflections to characterize the true sound of the source. However, a response that's completely consistent on and off axis is still likely to sound better.

I'll make the claim with confidence that my DSP-optimized DNA-360 sounds better than a 475 Be will, either out-of-the-box or when using only rough signal shaping to lift the top end. This is despite the fact that the DNA-360 has a rather severe break-up at 17 kHz. Of course, the 475 Be will probably beat the DNA-360 out-of-the box because of that break-up. I can't emphasize enough how important the DSP correction is to tame this break-up. It's a night-and-day difference in sound quality. Even if the 475 Be pushes break-up resonances above 20 kHz (which it better do, or else the Be is a big waste), other resonances are present in the response which will influence sound quality if they aren't addressed.

When using DSP to address resonances in general, one must be aware of two important things: First, you need polar response data. You can't discern resonances from diffraction phenomena without polar response data. If you try to correct diffraction peaks and dips with DSP, it will sound worse not better. Second, you need linearity data. Some resonances, particularly break-up resonances, behave non-linearly. Non-linearity can cause any EQ to malfunction spectacularly. Boosts can become dips and vise verse. If any resonances are non-linear within the expected operating range, then sound quality will be adversely impacted at high output levels. IMO, these two types of measurements are crucial to evaluate the potential performance of any CD + horn combo. Sadly, I have never seen linearity data for any combo of CD and horn, and most polar response measurements I've seen either don't extend to 20 kHz or use too much smoothing to see the effects of break-up resonances.

*****

Anyway, in my previous post, I asked you if you have a plan or any ideas of what you want to measure. I'd still like you to answer. The reason I'm taking the time to respond to these posts is because I am *genuinely interested* in seeing good measurement data. I posted a link to my own measurements to give you some ideas of what *I* think is useful to see.

I also just so happen to live in Denver, so I am in a position to lend a hand, depending on where you want to go with this.
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post #29 of 50 Old 04-19-2017, 04:21 PM - Thread Starter
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Quote:
Originally Posted by tuxedocivic View Post
Im on my phone. Search youtube for iwata 300 or something. Big red iwata horns. I have the measurements in a thread started by kingpin. The speaker design was for him.
Actually I did see that video. I'm flat baffle limited due to matrimony. I'm pretty happy with the SEOS combo for now. I'm glad you got to hear/work with a Be driver first hand. I'm not surprised you're on board.
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post #30 of 50 Old 04-19-2017, 04:37 PM - Thread Starter
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Ryan, dd you see any disadvantage using the larger format CD and EQ to the top to make it flat? Possibly issues off axis? Did the Be extend higher without EQ?
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