Dayton Reference tweeter RS28A-4

[capslock]

https://www.speakerdesign.net/

go to the Dayton RS28A-4 tab

Seems to be an Usher 9950 assembly with a Scan Speak 9800-like dome and an extra outside Faraday shielding ring in addition to the inside ring. Takes the fun out of driver-diy, because I was just developming ideas for my own perfect tweeter motor.

I would not be surprised to find that the dome is exactly the Scan Speak dome. Scan buys from Dr. Kurt Müller in Krefeld, one of the largest manufacturers of loudspeaker moving parts outside of China. Many of their OEM developments seem to be widely available now, such as the carbon paper cones and funny wide surrounds used on the 8535, 8545 and 8555.

[JonMarsh]

This looks basically like a metal dome version of the North Creek D28, which is reportedly built by Usher, and DOES have the Faraday rings as this driver has. I have a pair of those on load for evaluation- test results up at Mark's site.

An interesting question is will be how this sounds with or without the felt style phase plug; I've genderally found I preferred no phase plug at all when tweaking metal dome tweeters- its the first thing to go...

Thanks for the Link, I hadn't seen pictures before.

~Jon

[Scott Simonian]

Awesome tweeter. When does it come out and how much?

*ehhem*And when are you guys gonna churn up some nice projects with em?

[cjd]

Scott: I'll start messing soon as Dave updates his site with data. See the RS 3-way thread elsewhere.

I'll also see about retrofitting this into my MTM design. May be a fairly simple task. I'm already re-tweaking this to try and improve CC performance.

Darren posted that ETA is end of March at the very earliest, with their hopes being $35-50 on price.

C

[JonMarsh]

I have the OK to post this graph from MarkK; I think it's quite illustrative, as a comparison of the impact on high order distortion that the motor quality has. The black trace in the foreground is the prototype RS28A-4. The red trace in the "background is the Millenium Excel (one of mine, new, never mounted in system). This is the three tone cluster distortion test, centered at 1 kHz, for those wanting to guage the LF capability of this tweeter. Wherever you see red, the distortion of the Millenium higher.




:T :B 8)


~Jon

[TacoD]

I understand the distortion is higher for frequencies >5 kHz. My question is the following is the distortion at these magnitude/ frequency detectable by human hearing? I do not want the question these very good results of the RS28A, but does it make a difference. And another question, does the type of cone used in the tweeter interact with these measurements? Sorry I am new to this kind of testing.

[Paul H]

I suspect the real question to ask is regardless of whether the distortion is noticeable, why pay substantially more for a tweeter with more distortion?

Paul

[TacoD]

I suspect the real question to ask is regardless of whether the distortion is noticeable, why pay substantially more for a tweeter with more distortion?

Paul

If it sounds better.

[Mark K]

If it sounds better.

I guess it depends on how you look at it. Low levels of distortion can add perceived detail. Like a photoshop sharpening filter. Sounds good on some material, not on others. The problem is, if your tweeter distorts, everything you listen to will have this, like it or not.

[JonMarsh]

I understand the distortion is higher for frequencies >5 kHz. My question is the following is the distortion at these magnitude/ frequency detectable by human hearing? I do not want the question these very good results of the RS28A, but does it make a difference. And another question, does the type of cone used in the tweeter interact with these measurements? Sorry I am new to this kind of testing.

HF harmonic and intermodulation distortion?

One man's high frequency "air" is another man's distortion?

When comparing other factors, such as linear distortion, smoothness of frequency response, bandwidth, etc, what else really defines the sound? This is something that I think we're all trying to work towards a good understanding of how these things correlate- this is also assuming that neutral, uncolored reproduction is the ultimate goal.

These discussions and feedback from Mark and Eric have been invaluable to me, and has set a clear direction for investigation and evaluation.

Regarding your second question, the susceptability of the dome/cone material to non-pistonic operation does seem to affect the results one will get- a classic example is the harmonic distortion "amplification" effect above 1.5 kHz in the W18 Seas, due to the motor distortion being amplified by the cone "gain" at that frequency.

The lower the Q of the cone, the closer to pistonic behavior over a wide frequency range, the more neutral the reproduction of what the "motor" does. If the motor itself isn't as linear as desired, then the best diaphram in the world won't help. (are you listening, Eton?)

There are some clear patterns I see whether testing tweeters or subwoofers. Reduced inductive rise through Faraday rings results in less upper harmonic distortion- whether an aluminum dome tweeter, or an aluminum cone subwoofer driver! An the upper harmonics are not as muscially related to the signal as the 2nd or 3rd. 5th harmonic on 1 kHz is in a quite audible and sensitive part of the human hearing.

Regardless of our theoretical discussion, soon we will have some real answers, and as mentioned elsewhere, the proof of the pudding is in the eating.

My appetite's whetted...

~Jon

[GrahamT]

My appetite's whetted...

~Jon

Me too :E That graph is incredible! Very impressive. I hope these things aren't too expensive. :W I look forward to seeing more about this driver.

[Davey]

This was touched on previously in another thread, but what is the Xmax capability of the RS tweeter and is it comparable to the Millenium? Maybe when driven much harder and/or at lower frequencies the differences noted would be much less.

Cheers,

Davey.

[TacoD]

I guess it depends on how you look at it. Low levels of distortion can add perceived detail. Like a photoshop sharpening filter. Sounds good on some material, not on others. The problem is, if your tweeter distorts, everything you listen to will have this, like it or not.

That's true, but my cheap amplifier has better measured performance than my class A amplifier in the main system. And still I prefer the class A, I am sorry I cannot help it . I think the whole package is important, and it looks like only distortion measurements are important at the HTGUIDE clan :roll: .

[TacoD]

HF harmonic and intermodulation distortion?

One man's high frequency "air" is another man's distortion?

When comparing other factors, such as linear distortion, smoothness of frequency response, bandwidth, etc, what else really defines the sound? This is something that I think we're all trying to work towards a good understanding of how these things correlate- this is also assuming that neutral, uncolored reproduction is the ultimate goal.

These discussions and feedback from Mark and Eric have been invaluable to me, and has set a clear direction for investigation and evaluation.

Regarding your second question, the susceptability of the dome/cone material to non-pistonic operation does seem to affect the results one will get- a classic example is the harmonic distortion "amplification" effect above 1.5 kHz in the W18 Seas, due to the motor distortion being amplified by the cone "gain" at that frequency.

The lower the Q of the cone, the closer to pistonic behavior over a wide frequency range, the more neutral the reproduction of what the "motor" does. If the motor itself isn't as linear as desired, then the best diaphram in the world won't help. (are you listening, Eton?)

There are some clear patterns I see whether testing tweeters or subwoofers. Reduced inductive rise through Faraday rings results in less upper harmonic distortion- whether an aluminum dome tweeter, or an aluminum cone subwoofer driver! An the upper harmonics are not as muscially related to the signal as the 2nd or 3rd. 5th harmonic on 1 kHz is in a quite audible and sensitive part of the human hearing.

Regardless of our theoretical discussion, soon we will have some real answers, and as mentioned elsewhere, the proof of the pudding is in the eating.

My appetite's whetted...

~Jon

Thank you Jon, I am looking forward to these results, but I am also interested in subjective performance .

[Mark K]

A couple of years ago, when I started all this testing, I couldn't wait to test ribbons and the ow series. I loved the detail these tweeters gave. I assumed they would test well. I spent my own money-I've got a pair of ow1's, ow2's, raven R1's, AC G2si's. I was dismayed that they didn't test well in many respects (though in some respects they are quite good.)

I didn't know quite what to make of it-and still don't, sometimes. But after testing lots of drivers, certain patterns emerge. One of the patterns I see is that drivers with a modest amount of higher order distortion often have "detail and air."

Is there something wrong with my testing methods. I don't think so. People like distortion in their stratocaster, they like it in their digital photos, so why not in music? What I find interesting is that audiophiles don't really like to be told that they enjoy distortion. But that appears to be the case.

You never hear the audiophile talk about why his Raven R1 crossed with a single cap "has such beautiful distortion." Rather, some silly stuff about time alignment, low moving mass, etc.

But the bottom line is that what these audiophiles are doing is adjusting there system to provide just the right amount of distortion "to taste." Nothing inherently wrong with that, I think, if you're honest with yourself and you understand the limits of that approach.

[Davey]

Mark,

Well put.

It reminds me of the old saying....."You can believe the facts, or you can believe your ears."

I don't know who said that, and I haven't heard it in awhile, but it seems to apply to this case rather well.

Cheers,

Davey.

[Scott Simonian]

Sweet! When are these tweeters scheduled for production? Cost?

[JonMarsh]

As Chris posted earlier in the thread, ETA is late March or April. Price is expected to be in $40-50 range. Even at $50 these would be a bargain.

[Brian Bunge]

The more I see about this tweeter, the more I like it. I do have one question about the modifications. This may be strictly a question for Mark since I believe he's the only one here that has actually seen the tweeter first hand. Anyway, concerning the felt ring that's placed on the outside of the grill, is there any way that in could be installed on the underside of the grill, or would it come into contact with the diaphram by doing so? 'Cause I gotta tell ya, that little foam ring on the outside is butt ugly!

[JonMarsh]

In the case of Mark's RS28A, currently on loan to me, the grille is a little, teensy bit smushed, but even if it weren't the case, I think that the clearance between the dome and the grille is probably too tight to do that with the necessary clearance- keep in mind the original difusser is just a very thin piece of plastic. And the spacing is also a critical dimension. Being on the other side of the grill is mostly likely the only feasible way to do it with a ring of felt. Gonna have to use black felt to minimize the cosmetic issues, or cover with an ordinary grille cloth.

BTW, seeing this unit first hand cleared up one point- this isn't similar to the D28 Northcreek, because it is based on a 25 mm motor.

I'm going to do some of my own measurements next weekend, and will probably tweak up an exsiting system to try listening to it with. The impedance is in an acceptable range that I think I can get that to work pretty quickly.

I'm wondering if I should really share what my current take on this tweeter is... you know, most folks around this neighborhood don't pay much attention to old crazy Doc Emmet Brown.... but my impressions continue to coalesce that this is an SS9800 done right. And that's a good thing.

[capslock]

Jon, which one is based on a 25 mm motor? The RS28A? Why is it called RS28 then?

Regards,

Eric

[JonMarsh]

You've got me- I'll dig out the calipers later this week and double check everything- but holding the RS28A and the 9800 side by side, it's pretty easy to eyeball things- especially with a D28 on the table for comparison. Now, maybe my fever influenced vision is not accurate enough for this comparison- I will check carefully - but this doesn't look like a D28 - those extra three mm are pretty big. Stay tuned for a conclusive pronouncement, probably this evening.

[dlr]

It is 28mm

You've got me- I'll dig out the calipers later this week and double check everything- but holding the RS28A and the 9800 side by side, it's pretty easy to eyeball things- especially with a D28 on the table for comparison. Now, maybe my fever influenced vision is not accurate enough for this comparison- I will check carefully - but this doesn't look like a D28 - those extra three mm are pretty big. Stay tuned for a conclusive pronouncement, probably this evening.

I found this site and thread, so I thought I'd jump in.

The driver is 28mm. Darren pointed this out when reviewing my web page prior to posting it. That's the reason for the part number.

WRT the felt, there is not enough space between the dome and the grill. I tried it (can't really measure the gap). Contact prevents this. Too bad, as Brian stated, it's butt ugly. Part of the reason is that I had put some aluminum tape on top of the felt and added more felt over it in a further test. Removing this last top felt left the aluminum with the remnants of the felt (self-sticking) on the aluminum.

If you use a piece of black felt on it, I think it will be largely unnoticed. I used the brown felt because that and green were the only ones I've found easily available in stores like Home Depot. It's a precut pad.

Dave

[JonMarsh]

Thanks for the inputs, Dave, and clarification. I agree about the black felt. I'm also still inclined to say that, 28 mm or not, this tweeter strikes me as an SS9800 done correctly. Of course, it's in the listening that we'll have some of the proof of this pudding.

~Jon

[dlr]

I'm looking forward to auditioning a pair

Thanks for the inputs, Dave, and clarification. I agree about the black felt. I'm also still inclined to say that, 28 mm or not, this tweeter strikes me as an SS9800 done correctly. Of course, it's in the listening that we'll have some of the proof of this pudding.

~Jon

I'm interested in comparing it to the SS drivers. I currently use a 9300 pair (2.5K 2nd Order) that has roughly matched domes, using one from a 9500 and another replacement purchased to test. I swapped domes around to get this pair set up.

I prefer the 9300 over the 9500 due to the lack of the highpass irregularity of the 9500 and the 8K dip. The highpass irregularity is due (I think) to the chamber with the spike. The 8K dip is due to the symmetric felt dome on the pole vent, neither of which occur in the 9300.

I'm hoping that the decreased distortion of the motor will compensate for the 10K+ on-axis non-linearity as bing a worthwhile tradeoff.

But in the end I don't think that there'll be anything close in terms of price/performance.

Dave

[JonMarsh]

But in the end I don't think that there'll be anything close in terms of price/performance.

Dave

On that point I suspect I'm going to find myself in complete agreement with you, Dave.

[GrahamT]

I hope I can afford these things! :lol: They look great so far. Thanks for sharing Dave.

[cjd]

You guys whining about colored felt ever hear of that stuff called "dye"?

yeesh.

heh.

On the other hand, the wife may turn that into "die" pretty quickly, if you have such things to worry about.

C

[JonMarsh]

Well, I don't have the "wife" to worry about- black felt is fine with me, though I may actually prefer no felt or diffuser at all, as is usually the case with some other metal tweeters I've modded.

[cjd]

I meant, if you can't find black felt, you can make it black...

:P

Me, I have a rather forgiving wife. She may draw the line at open baffles where the back-sides are showing, but I have ideas already on how to deal with that! I think she doesn't care much for the amp I have with a clear plexi top. She still uses it without complaint.

C

[Jonasz]

Any news on the RS28 tweeter? Have anyone actually listened to a pair yet? :P

What is the Xmax of the Dayton? Looking at the datasheet of the SS9800 I notice it's only 0.1 mm, is that really correct? 8O I hope the Dayton has longer Xmax!

Jonas