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Multi-Way Conventional loudspeakers with crossovers

Dayton Reference Open Baffle Project
Dayton Reference Open Baffle Project
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Old 23rd November 2004, 01:26 AM   #21
Davey is offline Davey  United States
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Join Date: Dec 2001
Location: Bremerton, WA.
Thomas,

The RS180 is the driver of interest in this thread. Mark K. has also tested it and the problem seen with the RS225 is not really noticeable.

http://206.13.113.199/ncdiyaudio/mar...comparison.htm

Regarding the RS225....the primary cone breakup mode is quite a bit higher. The 1.6khz anomaly must be related to a cone edge/surround situation? It's interesting that the published curves on the PE website don't show any of this behaviour.

http://www.partsexpress.com/pdf/295-366g.pdf

Anyway, for dipole usage I still have my doubts about the RS180, but I could be wrong. I think I'll order a pair to play with on my spare baffles.

Cheers,

Davey.
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Old 23rd November 2004, 02:01 AM   #22
bilorn is offline bilorn  United States
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Join Date: Nov 2004
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Default dayton rs series

You might want to check the sd of the 6 inch, its compable to a 5 1/4. The reason is that the mounting flange is a bit wider than usual. Very nice heavy frame though, much beefier than Focal, Vifa, or Seas. I think the 7 inch would be closer to most 6 1/2s than the 6 inch. They don't give the cone areal in the specs, too bad.
good luck
bill horn
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Old 23rd November 2004, 02:52 AM   #23
cjd is offline cjd  United States
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Join Date: Jun 2004
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Default Re: dayton rs series

Quote:
Originally posted by bilorn
They don't give the cone areal in the specs, too bad.
good luck
They do list the diameter if you look at the impedance file (at the end is a pile of TS stats and such, including "D" or diameter...)

C
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Old 23rd November 2004, 03:09 AM   #24
bilorn is offline bilorn  United States
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Default dayton rs series

thanks for the info, i had overlooked the diameter.
comparison
seas p17rcy sd = 130cmsq dayton 7 inch rs. 123 cmsq.
seas p14rcy sd = 80cmsq dayton 6 inch rs. 81.7 cmsq.
with a xmax of 6mm the dayton 7 is probably a very good candidate for a open baffle design.
thanks again, I need to pay more attention.
bill horn
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Old 23rd November 2004, 06:01 AM   #25
dvdwmth is offline dvdwmth  Canada
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this is all looking very interesting. I might be a convert to this plan. i hadn't picked up on the reasons for the hype around this driver until today. Looking forward to seeing some projects popping up on the web.
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Old 23rd November 2004, 03:52 PM   #26
ThomasW is offline ThomasW
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Davey,

I'm well aware of Mark's measurements. He and Jon exchange info frequently.

Quote:
Regarding the RS225....the primary cone breakup mode is quite a bit higher.
Regarding Jon's data vs PE's.....

Let's just say that I'm pretty sure PE isn't using a testing lab with $250,000 worth of equipment. Nor are they using a $5000 labratory grade B&K 4133....

Cheers
Thomas
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Old 23rd November 2004, 05:12 PM   #27
JonMarsh is offline JonMarsh
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Join Date: Jan 2002
Location: Livermore, CA
Quote:
Originally posted by Davey
Thomas,

The RS180 is the driver of interest in this thread. Mark K. has also tested it and the problem seen with the RS225 is not really noticeable.

http://206.13.113.199/ncdiyaudio/mar...comparison.htm

Regarding the RS225....the primary cone breakup mode is quite a bit higher. The 1.6khz anomaly must be related to a cone edge/surround situation? It's interesting that the published curves on the PE website don't show any of this behaviour.

http://www.partsexpress.com/pdf/295-366g.pdf

Anyway, for dipole usage I still have my doubts about the RS180, but I could be wrong. I think I'll order a pair to play with on my spare baffles.

Cheers,

Davey.


One thing both Mark and I have seen is variance in the nearfield response (1-2") of a number of drivers from the farfield response. My own experience is that this seems more prevalent in the case of curvelinear type cones, like the Daytons and many ScanSpeak types.

Often the ultra nearifield measurements at different points on the cone surface (center, mid to edge, and edge) will reveal variations in the response which correlate with impedance anomalies or areas of energy storage.

My experience is that you get the best, most clear and natrual sound when you avoid using these areas.

Here's a couple of examples- first, a ScanSpeak Kevlar 8" midwoofer, such as Sigfried Linkwitz used in the Audio Artistry sytems...

There are several bobbles in the impedance curve, the first one being at ~700 Hz.



Click the image to open in full size.

The sweeps were measured at the center, mid way between center and edge, and at one edge.


Now, here's a driver that is rather better behaved, in my opinion, the HiVi M8a 8" woofer, measured in the same way.



Click the image to open in full size.


I think it's safe to say that the behavior is much more consistent, and indicative of cone behavior that is more pistonic through a wider range. The first impedance glitch is at 2.3 kHz.


MarkK has seen similar issues with near field testing of some drivers, showing substantial variation in the response at relatively low frequencies (<2 kHz) which are smoothed out in far field (1 meter) plots.

I think one ignores these "hints" from the measurements at a certain risk....

I've got RS180's on hand, and plan to order some RS150's this week also, and do some extensive testing, because I'm interested in using them in some MTM's, and they could be used in a dipole configuration, of course. It's just figuring out what range they perform best in.

I've also got RS270 10's to test. I'm interested in them for sealed and dipole applications.

A lot of work upcomging in December, but I have the whole second week of the month scheduled off for this. I'll be posting the results after I'm finished... right now, to guess at the optimal crossover frequecies from the available published data from PE would be nothing more than that... a guess.

~Jon
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Old 23rd November 2004, 06:19 PM   #28
Davey is offline Davey  United States
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Join Date: Dec 2001
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I don't have any trouble believing Mark's and Jon's measurements are more representative of the true nature of these drivers. I was just making an observation regarding the PE published data.

I think you fellas are losing track of the point I was trying (rather poorly I guess) to make regarding the Dayton Reference driver (the RS180.) The behaviour of the drivers themselves is one parameter (as you've noted/evidenced with your measurements,) but I'm only talking about their suitability for dipole usage...ie, how the rear radiation interacts with the front via the baffle shape and its overall effect on the horizontal polar response of the system. This is still unclear to me.
Jon, you say "they could be used in a dipole configuration, of course," but with all due respect I think you're speculating about that possibility until some further testing is accomplished. I'm assuming some kind of methodology similar to SL's would be appropriate (that's what I try to do,) but maybe you don't weight the significance of this as highly as he does?

I'll be interested to see the results of your driver testing.

Cheers,

Davey.
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Old 23rd November 2004, 09:21 PM   #29
transducer is offline transducer  Canada
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Davey,

Can you elaborate on testing for rear radiation problems? Truthfully, I'm worried about the HiVi M8A woofers that I'm going to use in my dipole, they don't look to be a very open design, say compared to the Vifa MG22 woofers that I've got stashed away. Of course those ones have a problem around 1k, as is typical for SS and Vifa drivers.

Ron
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Old 23rd November 2004, 09:53 PM   #30
cjd is offline cjd  United States
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Join Date: Jun 2004
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I should have some RS150's on hand this evening (6 of 'em) intended for ported MTMs... however, as I always do custom templates for routing the drivers in, I haven't routed yet - so I can easily toss together a baffle or two to try them open baffle while I'm routing the other baffles.

Probably a good idea anyhow as I'm suspecting I'll be putting together a fairly big open baffle setup for music listening one of these days.

C
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