Hmm, Dayton RS28F - F??? What have we here?

[KeithL]

Re: What midbass used here?

He's using the Auram Cantus AC130F-1 : http://www.parts-express.com/pe/show...number=296-400

See a post of his about it here: http://techtalk.parts-express.com/sh...4&postcount=11

That explains why it is rear mounted.

[DDF]

Re: Hmm, Dayton RS28F - F??? What have we here?

I'd go so far as to say forget the HD (except as an easily measured proxy for more audible distortion) . . . it's the IM and resonances and aliasing and noise that place signal at frequencies and times where they were not in the original (along with cone breakup and reflection and re-radiation in and from speaker boxes). And I'd be repeating what has been known, and said, and mostly ignored, for decades.

MLSSA will measure uncorrelated Noise+distortion (and has for 20 years probably), so someone is listening. These plots can be very illustrative of issues localized over a frequency range by the presence spikes in the plot over f.

I find them hard to interpret when low in level though. How bad is one smooth plot vs another and what is the threshold crossed where the illustrated performance is problematic?

Klippel also provides a measure where he looks at the time variance of the non linearities by plotting rms and peak anomilies over frequency. This is especially helpful since most "meters" don't average sound over time the same way the ear does.

Dave

[DDF]

Re: Hmm, Dayton RS28F - F??? What have we here?

Dave,

The stimulus is a 3 tone test. It's the same one SL uses. I've been using it so long it's just a convenient, well known and interpretable test for me. I know there are pros and cons to this three tone test, but I've developed a fondness to it that I don't have for simple HD testing.

http://www.linkwitzlab.com/frontiers.htm#G

So it's all HD+IM.

Mark, thanks for clearing that up. I've grown attached to using multi tone tests too, they provide a good visual indication of the clutter from IM with real signals. I weight my tone inputs to be more representative of the spectral density of real music.

Dave

[DDF]

Re: Hmm, Dayton RS28F - F??? What have we here?

sub harmonics are produced by IM as well. 10KHz and 11KHz will produce a 1KHz sub harmonic.

Of course, but please reread my post: "sub harmonics are never mentioned for one tone tests"

The issue is sub harmonics with a single tone input.

I think we all know the definition of IM distortion.

Dave


PS Just saw mark's post. I was working on the assumption dlr was asking about sub-harmonics with a one tone test based on his comment "there is a spike seen on all of the measurements that appears to be precisely at a subharmonic of 1/5 of the fundamental".

[critofur]

RE: What midbass used here?

Jeff,

Just curious as to what midbass is being used here?

He's using the Auram Cantus AC130F-1 : http://www.parts-express.com/pe/show...number=296-400

See a post of his about it here: http://techtalk.parts-express.com/sh...4&postcount=11

[KeithL]

Re: Hmm, Dayton RS28F - F??? What have we here?

You heard it in my little speakers in Auburn, this past spring.

Jeff,

Just curious as to what midbass is being used here?

[critofur]

Re: Hmm, Dayton RS28F - F??? What have we here?

So the 28F is not interchangeable with the 28A, correct?

Did you see this picture earlier in the thread?:



I've seen more variation between some tweeters of the same exact model, than between the RS28A and RS28F in the "crossover range" - I wouldn't worry so much about the high frequency variation (above 10Khz) other than to say the F will be a little flatter 15 - 30 degrees off axis than the A due to the slightly rising response on the top end.

If you do switch an F in place of an A, nothing more than an L-pad, or, half an L-pad should do the trick? I would listen without any changes first though.

[Deward Hastings]

Re: Hmm, Dayton RS28F - F??? What have we here?

http://www.linkwitzlab.com/frontiers.htm#G

So it's all HD+IM.

I'd go so far as to say forget the HD (except as an easily measured proxy for more audible distortion) . . . it's the IM and resonances and aliasing and noise that place signal at frequencies and times where they were not in the original (along with cone breakup and reflection and re-radiation in and from speaker boxes). And I'd be repeating what has been known, and said, and mostly ignored, for decades.

[markk]

Re: Hmm, Dayton RS28F - F??? What have we here?

I guess the F in RS28F stands for: Fantastic, or, Fabulous?

Mark, what do you think about the power response of your RS225-28 2-way design in terms of how it relates to the listening experience. Compared, say, to your more recent designs.

I have no idea if this applies to your RS 2-way - but some people have commented about other all metal RS designs they had, they enjoyed the clarity, and some other aspects, but in the end, found them a little too "harsh" and "fatiguing".

I do know that I have REALLY liked RS225 speakers in some that I have heard, including 2-ways (albeit with non-metal tweeters).

I had some paper woofer paper tweeter inexpensive 2-way bookshelf speakers from the 70's that I used to find really enjoyable for listening to pop + rock records, radio, mix tapes. Don't recall if they had any "imaging" and I never said "wow, they're so revealing, I never heard that part of the music on other stereos" :P

I don't think my RS22528A is in any way fatiguing. I think that many systems are a bit bright/forward. (see dBe's comments) If a metal coned system is slightly bright, the blame is laid on the cone material. If well designed, metal cones shouldn't sound bright/edgy/fatiguing. Lot's of paper cones sound bright and fatiguing... Still, it takes some effort to really tame metal cones.

The power response is a different question, and I do think that higher order xovers have a certain presentation. I'm loath to overgeneralize based on the N=1 study of my ER18DXT vs every other speaker I've designed which is 4LR or higher...

The problem with using a metal cone is that it's almost mandatory to use 4lr or higher to tame the metal, so clear comparisons can't be made. I do think that "fatiguing" is mostly in the crossover, then the source material.

So the 28F is not interchangeable with the 28A, correct?

You mean as a drop in replacement in a completed design? I don't think so, although I bet it's pretty close. You shouldn't have to make much more than some small changes to whatever xover you're using.

[markk]

Re: Hmm, Dayton RS28F - F??? What have we here?

Mark would be the go-to guy to answer these, but other than the jammie chaffing raised by Pete, the usual cause of frequency dependant buzz in a good driver is driver mounting.

If it's truly a sub-harmonic, that's pretty rare. I read through Klippel's site again, and sub harmonics are never mentioned for one tone tests, just multi-tone (maybe there's hum in Mark's set up?). It would be odd to see it across a number of drivers with one tone present.
This paper predicts sub-harmonics as appearing just before the driver goes chaotic:

http://www.elec.qmul.ac.uk/people/josh/documents/ReissDjurek-AES125-ChaoticLoudspeaker.pdf

This one could shed light, but I don't have it:

http://www.aes.org/e-lib/browse.cfm?elib=12584

There's also a mechanism which creates sub-harmonics in compression drivers (my guess is excessive throat velocity creating distortion in the air itself), but that wouldn't apply here.

Dave

Dave,

The stimulus is a 3 tone test. It's the same one SL uses. I've been using it so long it's just a convenient, well known and interpretable test for me. I know there are pros and cons to this three tone test, but I've developed a fondness to it that I don't have for simple HD testing.

http://www.linkwitzlab.com/frontiers.htm#G

So it's all HD+IM.

[Wushuliu]

Re: Hmm, Dayton RS28F - F??? What have we here?

So the 28F is not interchangeable with the 28A, correct?

[critofur]

Re: Hmm, Dayton RS28F - F??? What have we here?

I guess the F in RS28F stands for: Fantastic, or, Fabulous?

Mark, what do you think about the power response of your RS225-28 2-way design in terms of how it relates to the listening experience. Compared, say, to your more recent designs.

I have no idea if this applies to your RS 2-way - but some people have commented about other all metal RS designs they had, they enjoyed the clarity, and some other aspects, but in the end, found them a little too "harsh" and "fatiguing".

I do know that I have REALLY liked RS225 speakers in some that I have heard, including 2-ways (albeit with non-metal tweeters).

I had some paper woofer paper tweeter inexpensive 2-way bookshelf speakers from the 70's that I used to find really enjoyable for listening to pop + rock records, radio, mix tapes. Don't recall if they had any "imaging" and I never said "wow, they're so revealing, I never heard that part of the music on other stereos" :P

[markk]

Re: Hmm, Dayton RS28F - F??? What have we here?

Hi guys,

This is what to expect, courtesy of SL-there can be much more of course!



The subharmonic is a pretty typical constant

I'll have more to say about the hash later (work) but that is very important!

[Pete Schumacher]

Re: Hmm, Dayton RS28F - F??? What have we here?

Mark would be the go-to guy to answer these, but other than the jammie chaffing raised by Pete, the usual cause of frequency dependant buzz in a good driver is driver mounting.

If it's truly a sub-harmonic, that's pretty rare. I read through Klippel's site again, and sub harmonics are never mentioned for one tone tests, just multi-tone (maybe there's hum in Mark's set up?). It would be odd to see it across a number of drivers with one tone present.

This paper predicts sub-harmonics as appearing just before the driver goes chaotic:

http://www.elec.qmul.ac.uk/people/josh/documents/ReissDjurek-AES125-ChaoticLoudspeaker.pdf

This one could shed light, but I don't have it:

http://www.aes.org/e-lib/browse.cfm?elib=12584

There's also a mechanism which creates sub-harmonics in compression drivers (my guess is excessive throat velocity creating distortion in the air itself), but that wouldn't apply here.

Dave

sub harmonics are produced by IM as well. 10KHz and 11KHz will produce a 1KHz sub harmonic.

[DDF]

Re: Hmm, Dayton RS28F - F??? What have we here?

What would be the influence of that on distortion measurements?


dlr

Mark would be the go-to guy to answer these, but other than the jammie chaffing raised by Pete, the usual cause of frequency dependant buzz in a good driver is driver mounting.

If it's truly a sub-harmonic, that's pretty rare. I read through Klippel's site again, and sub harmonics are never mentioned for one tone tests, just multi-tone (maybe there's hum in Mark's set up?). It would be odd to see it across a number of drivers with one tone present.

This paper predicts sub-harmonics as appearing just before the driver goes chaotic:

http://www.elec.qmul.ac.uk/people/josh/documents/ReissDjurek-AES125-ChaoticLoudspeaker.pdf

This one could shed light, but I don't have it:

http://www.aes.org/e-lib/browse.cfm?elib=12584

There's also a mechanism which creates sub-harmonics in compression drivers (my guess is excessive throat velocity creating distortion in the air itself), but that wouldn't apply here.

Dave