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1 inch CD Comparison (SEOS18) - Page 3

post #61 of 201
oh, I see that its only a 1" exit. Still Nice that it goes below 700Hz!!
post #62 of 201
Sorry to hijack but Penn, if you want to listen to the SEOS12/DNA360/AETD12M combo I should have them wrapped up pretty soon.
post #63 of 201
Thread Starter 
I'm new here, but boy, is penngray popular! You're not a supermodel, are you? biggrin.gif
post #64 of 201
Quote:
Originally Posted by filtor1 View Post

Sorry to hijack but Penn, if you want to listen to the SEOS12/DNA360/AETD12M combo I should have them wrapped up pretty soon.

really? Well done!!
post #65 of 201
Quote:
Originally Posted by rahula7 View Post

I'm new here, but boy, is penngray popular! You're not a supermodel, are you? biggrin.gif

I just had a minor addiction at one time (25K posts in 5 years wink.gif ) and I stay at Holiday Inns when traveling wink.gif
post #66 of 201
Quote:
Originally Posted by rahula7 View Post

I'm new here, but boy, is penngray popular! You're not a supermodel, are you? biggrin.gif

He is the only audio guy I know of in my area that is a member here. It seems there are not a ton of DIY audio guys in Florida outside of car audio.
post #67 of 201
Quote:
Originally Posted by penngray View Post

really? Well done!!

Yeah man. The offer is there if you ever have a free minute.
post #68 of 201
Quote:
Originally Posted by penngray View Post

25K posts in 5 years wink.gif

And pretty vocal posts too wink.gif
post #69 of 201
Quote:
Originally Posted by countryWV View Post

Rahula7
Great thread!! I appreciate the work and time you are putting in to this. Very Interesting.
The bigger the waveguide the more the differences will be revealed. We have know this from the beginning and now its time to find out how much.

That's not necessarily true. I've tested them on the SEOS-18 and none look like what the OP posted. If 2 nearly identical CD's test the same on a SEOS-12, they won't look completely different on a SEOS-15 or SEOS-18.

It's very obvious to see something is wrong when you look at the low end. And the high end is not even close to normal. That means something unusual has happened. And because he said he's been running the 360 at 800hz and possibly experimenting lower, I'd say the problem has been narrowed down......the diaphragm has been strained and needs replacing. That's also why all brands sell replacement diaphragms so the pro guys can replace them if they did something unusual. smile.gif


Put the BMS or the DE250 on the SEOS-18 and let them try to keep up with a 15" - 18" woofer crossed at 800hz or less.......they'll have similar issues.
post #70 of 201
Quote:
Originally Posted by Erich H View Post

Put the BMS or the DE250 on the SEOS-18 and let them try to keep up with a 15" - 18" woofer crossed at 800hz or less.......they'll have similar issues.

with enough narcotics in me to knock out an elephant and kill the pain of torn disks in back, I'm likely not censoring myself appropriately... But you've now said it multiple times in this thread that drivers (specifically BMS) will not work and be damaged at an 800Hz crossover..... Unless you've got documented proof with multiple units over long term testing at rated power with failures, please just stop saying it. At best it's misrepresenting the product. at worst......

B&C specifically states on their website that they don't recommend a crossover that low. That's good "CYA" on their part.... any experimentation below their 1.6K recommended cross, they are covered if anything is damaged. The OP is playing at his own risk to use an 800hz crossover on the DE250 since it flies in the face of B&C's explicit recommendations.

However, BMS says right on their website that they *recommend* a 800Hz crossover. They are encouraging owners of the driver to use a crossover that low..... there is not as much specific detail on their website as, say, JBL or B&C, as to minimum crossover slope needed at that crossover frequency, nor is there a power rating with that min crossover slope (unless you assume that BMS's 80W power rating listed for the 4550 is at 800hz recommended cross)... but the key point is that BMS is not a stupid company. They're not going to put it in black and white on their website unless they are sure the driver can handle it.... It's a recipe for lawsuits and them having to supply free diaphragms under warranty if folks use their recommended crossover and diaphragms fail...

NOT saying anything at all about the quality of sound if using an 800Hz crossover versus something else.... just that, in the face of zero evidence of any bms 4550 diaphragms being damaged with their recommended crossover, it might be best to defer to the manufacturer and give them the benefit of the doubt instead of trying to lump it in with other drivers that don't go that low.... and there are other 1.75" diaphragm 1" exit CDs that will go to 800Hz besides the BMS... JBL makes one: http://www.jblpro.com/pub/components/2426.pdf ........rated for 70W of input power with a 2nd order slope at 800Hz....
post #71 of 201
Quote:
Originally Posted by tuxedocivic View Post

I'd disagree with this. 8th order has such a sharp knee compared to the 4th and 6th order that the steeper slopes will actually strain the CD more IMO. Below the -6db point, they all roll off quickly enough that excursion is reducing. See the transfer functions here:


Seems to me that because excursion decreases with the square of freq that higher order will increase protection much more than a dB or two near the nominal XO point.
post #72 of 201
Thread Starter 
Alright boys and girls, this is how the inside of a compression driver looks like smile.gif

Some pics of the DNA360 I have and its insides. What do you think Erich? That diaphragm and VC looks in pretty good shape. If you still think something is wrong, I don't mind getting updated diaphragms.






post #73 of 201
Maybe your measurements are erroneous. How do you explain why Erich and others have measured the DNA360 and have had different results? Are all of them wrong and you're right?
post #74 of 201
This is good stuff.

I don't see anything wrong with that diaphragm but have not looked inside my DNA-360 either so I can't say it is different. I do agree the response graphs looks for it funny but I have my doubts it was damaged by the low crossover point, this is especially true if never taken to concert levels. I have seen CD VC's get bumped out of alignment during shipping and make the response look screwy. Try remeasuring, sometimes it will reset itself after you pull it apart and put it back together.
post #75 of 201
Quote:
Originally Posted by noah katz View Post

Seems to me that because excursion decreases with the square of freq that higher order will increase protection much more than a dB or two near the nominal XO point.

Ok, which slope has more protection above 800hz?

Which has the most AT 800hz? (That one is easy, they're all the same)

Which has the most protection below 800hz?

The first question is pretty easy. The LR4. The second question is exactly the same. The third question is trickier. What does the excursion profile of a CD look like? Well it looks like a sealed woofer, so there's essentially no excursion and then below its resonance frequency it starts to pick up, and then flat lines at some point just below resonance. We know that 24db/oct easily suppresses excursion for these CD within the rated power rating and even more than that. So we can then see the driver is most vulnerable just below resonance. So if the -6db point is just a little more below resonance, which slope is best?

Now look at the distortion. We know that 24db/oct easily suppresses the very large swing in in distortion below 800hz. Which transfer function will reduce the mild rise in distortion best between 800 and 1000hz? The LR4 does this best.

It's counter intuitive that the shallow slope offers more protection, but in reality it can. Now if we were comparing BW1 and BW2 or LR2, absolutely the higher order slopes are WAY more protective.
post #76 of 201
Thread Starter 
Quote:
Originally Posted by rajacat View Post

Maybe your measurements are erroneous. How do you explain why Erich and others have measured the DNA360 and have had different results? Are all of them wrong and you're right?

Can you be more specific? Which part do you think is erroneous?

I'm not here to show there is something wrong with the DNA360. Let me give some background. I was using 2" CDs and large horns, but I'm convinced that the sweet spot is with the SEOS-18 or even SEOS-24 and a 1" driver crossed over at 700 Hz or so and extending all the way up. After the 2" CD, I was happily, yes happily, using the DNA360 on SEOS-12 until I received the SEOS-18.

On the SEOS-18, my measurements were not lining up with Bill W's. But his used the DE250. I ordered the DE250 and the others to see which one is best. Now, the DE250 lines up with Bill's measurement. So, it doesn't look like there is anything wrong with the measurements. I'm willing to accept that my drivers may be damaged or defective. And I'm more than willing to pay for replacements.

I have ordered lots of stuff from Erich, and I don't plan on stopping now.
post #77 of 201
Thread Starter 
Quote:
Originally Posted by mtg90 View Post

This is good stuff.

I don't see anything wrong with that diaphragm but have not looked inside my DNA-360 either so I can't say it is different. I do agree the response graphs looks for it funny but I have my doubts it was damaged by the low crossover point, this is especially true if never taken to concert levels. I have seen CD VC's get bumped out of alignment during shipping and make the response look screwy. Try remeasuring, sometimes it will reset itself after you pull it apart and put it back together.

Yeah, I'm going to get a measurement in tonight to see if something has changed. I can even pop the diaphragm of the DE250 into the DNA360, seeing as they are clones. But I'm loathe to open the DE250 as I might be sending it back.
post #78 of 201
Here is something to compare it to, I tried to replicate your testing procedure but could not do it outdoors at 10:30pm:




biggrin.gif

post #79 of 201
Thread Starter 
Is that a DNA360? Now that makes me feel something is wrong with my drivers. Can you open it and take a pic of the diaphragm? Takes a couple of minutes.

Thanks very much!

What are you planning to do with the SEOS-18? Which driver, crossover point and target?
post #80 of 201
Rahul, I figured out the problem........

That's NOT a DNA-360 that you're using and testing. That's the 350. I can spot them easily. Different diaphragm, phase plug, internal foam, different screws, terminals, etc.

So I looked back at your order from August of last year and you did indeed order the 350, not the 360.

That was a lot of worry for nothing my friend. wink.gif I hope you can change the first post so people know that's not the 360 because it makes them look bad.....when I know they're quite nice. There was a LOT of work put into the 360 and many people have tested them. I hope anyone that read this thread gets to this page to see that there was a flaw in the graphs.

Honestly, I read this thread last night and the charts really baffled me. Actually I would say they upset me a bit. I think my last post edit was about 3:00 in the morning. rolleyes.gif I kept thinking to myself, how in the world can those charts look like that, I test every single driver before shipping. I'm nuts about it too. For the 360's, I take it a step farther and test my DE250's first, leave the measurements on the screen, then test my 360's. No 360 gets shipped unless it extends further on the high end and at least matches them on the low end. That was the goal for that model from the beginning and I want to make sure that's what people get. It was a lot of extra work, and my living room has been turned into a CD testing facility.....but that's okay.




The 350 has a recommended crossover point of 1200hz. If you ran it at 800hz to keep up with that big woofer and tested at 700hz, I'd say it's been strained way too hard and that's why there are issues. That's way under where it should be and simply not intended to be used like that.

It's been mentioned many times that the 350 should only be used from 1200hz on up, and also says that on the site. If you want to send them back for an upgrade to the 360, that's fine. Or send them back to me and I will change out the guts of that 350 for you. Either way, the problem has been figured out. I feel relieved, but this thread is going to be confusing for some.
Edited by Erich H - 6/19/13 at 10:00pm
post #81 of 201
Thread Starter 
Excellent. Thanks Erich. I don't know why I ordered the 350.

Anyway, that is a mistake and let me change the first post immediately.

Glad we sorted this out, now we can get on with the regular program.

Anyone want a pair of DNA350s? smile.gif
post #82 of 201
I too am glad that got sorted out, well here is the 360 guts since I went through the trouble:





Quote:
What are you planning to do with the SEOS-18?

Just testing along with many others:
http://www.avsforum.com/t/1475674/the-great-waveguide-shootout

It does look nice on top a 15" box though smile.gif
post #83 of 201
Quote:
Originally Posted by tuxedocivic View Post

...What does the excursion profile of a CD look like? Well it looks like a sealed woofer, so there's essentially no excursion and then below its resonance frequency it starts to pick up, and then flat lines at some point just below resonance.

Are you sure?

What's the back volume compared to its Vas?

If small, then you're right; otherwise it may be closer to an IB and what that implies.

I don't believe CD spec's include Vas, so the only way I can think of to verify is to compare free-air Fs with Fs assembled with the compression chamber.
post #84 of 201
Quote:
Originally Posted by mtg90 View Post

Here is something to compare it to, I tried to replicate your testing procedure but could not do it outdoors at 10:30pm:



Oh yeh, the DNA-360 rocking like it was intended. That looks like the real deal.

Even though it looks nice way down there around 800hz, I'd still worry about running them hard crossed over that low. As mentioned earlier, I wouldn't run the DE250 or BMS 4550 that low either. It's just asking for trouble if someone decides to really crank them up. But I suppose they all sell replacement diaphragms for experimenting.
post #85 of 201
Well, even if it behaves like an IB, 24db/oct will still suppress excursion very quickly.

Ill play in winisd and see what I can generate to show what I mean. Graphs help everyone learn. And maybe I'm wrong wink.gif
post #86 of 201
Quote:
Originally Posted by hometheaterdoc View Post

But you've now said it multiple times in this thread that drivers (specifically BMS) will not work and be damaged at an 800Hz crossover..... Unless you've got documented proof with multiple units over long term testing at rated power with failures, please just stop saying it. At best it's misrepresenting the product. at worst......

However, BMS says right on their website that they *recommend* a 800Hz crossover. They are encouraging owners of the driver to use a crossover that low..... but the key point is that BMS is not a stupid company. They're not going to put it in black and white on their website unless they are sure the driver can handle it.... It's a recipe for lawsuits and them having to supply free diaphragms under warranty if folks use their recommended crossover and diaphragms fail...

I didn't say they wouldn't work. I said that they could be damaged eventually if run too low.

BMS also claims a peak power of 450 watts. Would you run the 4550 crossed at 800hz with one channel of a Behringer EP2500? They claim a FR from 500hz. But look at their graphs. It's not even close, so why try and claim it? No one's going to sue them. If so, Pyle would have been sued 20 million times by now.

http://bmsspeakers.com/fileadmin/bms-data/product_data_2011/compression_drivers_ferrite/bms_4550_2011-04_hf_compression_driver.pdf

As mentioned before, I think BMS makes great products and I liked the way the 4550 sounds because it sounds like the DE250 and 360. But the BMS technical info is full of what I like to call salesman talk. I see no reason for them to do that because their products are good. Their diaphragms use the same material as well.

I would not run a 4550 and expect anything around 500hz. Nor would I cross them at 800hz and expect them to take 450 watts. As mentioned, I would not experiment around 700hz with any of them trying to keep up with a 15"+ woofer because I think they would eventually experience damage. Yes, I said eventually.
Edited by Erich H - 6/19/13 at 10:44pm
post #87 of 201
OP-can you tell us anything about how some of the 2" CD's have compared to these 1" CD's that you are testing? I am most curious about the Radian 950PB, (or 951PB 1.4"), the BMS4590, and maybe the JBL-2446? Is the main problem with using a 2" CD in a 2-way design, getting the 2" CD to extend upwards around 20khz? Are there any decent 2" CD's that will go up that high and also have the ability to crossover to a 15" woofer at say 700hz to 800hz?

I would personally like to see someone do a 3-way build using a 1" CD for the tweeter and then a 2" CD for the mid-range portion. I do, of course, realize that the crossover will be more complicated and could possibly sound worse due to the disadvantages of a 3-way versus a 2-way, but me personally, I would love to see some kind of 3-way build that uses something like a Radian 950PB for the mids, and an AE TD12x or TD15x, not sure which tweeter would be best, though.
post #88 of 201
Quote:
Originally Posted by rahula7 View Post

Can you be more specific? Which part do you think is erroneous?

I'm not here to show there is something wrong with the DNA360. Let me give some background. I was using 2" CDs and large horns, but I'm convinced that the sweet spot is with the SEOS-18 or even SEOS-24 and a 1" driver crossed over at 700 Hz or so and extending all the way up. After the 2" CD, I was happily, yes happily, using the DNA360 on SEOS-12 until I received the SEOS-18.

FWIW, I spent several years trying to get the 1" driver to have a 700Hz XO but I never had ultimate success with it. I spent many, many hours online here and on DIYAudio/audiokarma, etc discussing/reading about all options. The only 1" driver that does it remotely well is the TAD TD-2001 and even then 700Hz is just too low of an XO point. This even includes Geddes designs (rave reviews) using the B&C DE250 and a XO just under 1KHz. My final test would have been to use the DEQX and a brick wall filter and a 300dB slope but at that time I found the TD-4001s gave me the sound that I loved so much and I just stopped searching.

The conlusion for me is a pretty simple one. Audio is all about compromises and how we minimize our compromises. Laws of physics simply get in the way of having one driver do it all for us.

Someday I might jump back in and buy a DEQX then I can start playing around again. Maybe even a Coral H100 super tweeter biggrin.gif
Edited by penngray - 6/20/13 at 6:58am
post #89 of 201
Quote:
Originally Posted by Martycool007 View Post

OP-can you tell us anything about how some of the 2" CD's have compared to these 1" CD's that you are testing? I am most curious about the Radian 950PB, (or 951PB 1.4"), the BMS4590, and maybe the JBL-2446? Is the main problem with using a 2" CD in a 2-way design, getting the 2" CD to extend upwards around 20khz? Are there any decent 2" CD's that will go up that high and also have the ability to crossover to a 15" woofer at say 700hz to 800hz?

I would personally like to see someone do a 3-way build using a 1" CD for the tweeter and then a 2" CD for the mid-range portion. I do, of course, realize that the crossover will be more complicated and could possibly sound worse due to the disadvantages of a 3-way versus a 2-way, but me personally, I would love to see some kind of 3-way build that uses something like a Radian 950PB for the mids, and an AE TD12x or TD15x, not sure which tweeter would be best, though.


2" CDs have frequency range up to 20KHz, that is not the problem. The problem is where the 2" CD loses its directivity and beaming up high occurs (size of the horn matters for this too). High frequencies/beaming and its importance is an entire topic on its own. People that have had JBL designs with 2" CDs love them period. I have TAD 2" CDs and I do not find anything wrong with them...for high frequency I compare them to my Ribbon designs which have the best HF I have ever heard. I know what they lack and it does not outweigh the mid range performance gain.

Content will dictate your requirements and your subjectivity. ie...for me > 15KHz is far, far less important. People like Geddes have stressed that you have to focus on the most important range instead of worry about a frequency range that might not matter a great deal.

(For me) 2" CDs are superior to 1" CDs in the mid range. Does that performance gain matter more then a possible beaming issue higher up?


You should search DIYAudio for builds using the Radian 950 in a 3 way design, I think there has been a couple on there.
post #90 of 201
Thread Starter 
Quote:
Originally Posted by penngray View Post

FWIW, I spent several years trying to get the 1" driver to have a 700Hz XO but I never had ultimate success with it. I spent many, many hours online here and on DIYAudio/audiokarma, etc discussing/reading about all options. The only 1" driver that does it remotely well is the TAD TD-2001 and even then 700Hz is just too low of an XO point. This even includes Geddes designs (rave reviews) using the B&C DE250 and a XO just under 1KHz. My final test would have been to use the DEQX and a brick wall filter and a 300dB slope but at that time I found the TD-4001s gave me the sound that I loved so much and I just stopped searching.

The conlusion for me is a pretty simple one. Audio is all about compromises and how we minimize our compromises. Laws of physics simply get in the way of having one driver do it all for us.

Someday I might jump back in and buy a DEQX then I can start playing around again. Maybe even a Coral H100 super tweeter biggrin.gif

Penngray, your experience is interesting because I'm coming from the other way. I started with 2" and decided it wasn't doing it for me. Yes, the midrange is extraordinary, but the imaging and HF suffers. The sweet spot would be a BA-750 or TAD-2001 or a similar driver with a SEOS-18 or SEOS-24. Those horns can extend low near 700 or 800 Hz and go all the way up to 20 kHz. Agree that the midrange won't be as glorious. But there is something wrong in the way the sound is presented by a large horn and a 2" CD, at least to me. And I don't get that from the SEOS-18. My brain is relaxed, there is a sense of cognitive ease. It's getting all the info it needs at the right time. Imaging is very stable. And the midrange is still very very good.
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