I've found that the polars on the K-402 way up high are still very wide, perhaps leading you to believe that the horn is experiencing "harshness" sound quality. When the throat lens is installed, the sound is basically the same, even off-axis.
I've also found that once I flatten the phase response to within ±90 degrees from 100-20,000 Hz, any perceived harshness disappears.
YMMV.
Chris
So what does the distance from the acoustic center to the exit of the slot have to do with the audibility of said diffraction? I've found that all the problems are with horns having a 1/4 wavelength distance from the acoustic center to the end of the diffraction slot (and also a function of the diameter of the slot) that's in the 1-10 kHz range.
Chris
Well, the K402 does sound quite smooth with AXi2050. But that greatly due to the fact the driver is covering over details with distortion IMO.
A horn that uses a 2" exit and goes all they way up is old school.
A horn that uses a 2" exit and goes all they way up is old school.
The Teal is a CD waveguide at 55cm and the Pink is an Exponential at 1m. Different rooms only make this comparison less objective but its all I got so far. My Room in Pink is all hard boundary and the Teal had hard boundaries but room treatment.
I would respectful argue that this is true yet unless this holds true with the Loudspeaker+Room System, it won't matter. Exaggerated; a Be driver in a reverberating chamber vs Paper driver in an anechoic chamber. The constant directivity waveguide shows its constant off axis nature brings the room response into the HF. The rising directivity waveguide shows itself ever increasingly removing HF reverb by the time it hits its upper cutoff. If we were to bring the microphone out from 55cm to 100cm the rt60 would change for the worse which the Exponential waveguide is already cleaner in the regards of decay, in the HF.
Last edited:
Really?
I have no doubt that this is common knowledge in the field, but from the way you describe this, it appears like you are mixing them up a bit.
And here it happens again.
Acoustic center of a compression driver is not a single thing. I think I understand now how you are thinking, but you have to separate between the acoustic center of the wave front (this relates to the radius of the wave front), and the total depth of the horn-driver combo (this relates to loading and cutoff).
I agree that we need to be able to back up claims, but the topics I have mentioned are really basic, I do not think we need to go very deeply into discussions of validity. I recall you have talked about your development experience, so I am sure I do not need to educate you on basic topics. But I promise I will give some more background if we dive into something a bit further from common knowledge. At the same time, talking about your listening experience is not the same as backing up claims, so I think the slightly agressive tone when I asked what you really disagreed on was uncalled for. But let's leave it with that.
So, in order to progress further, I think both me and Mr Omholt agrees with you that conical horns have wide dispersion at high frequencies. The level of loading is determined by the angle of the horn, and that also defines the dispersion. The issue with conical horns and OSWG is HOM, and that does not affect polar response, harmonic distortion or frequency response. The first description of HOM that I know of comes from a study by Hoersch in 1925. This was related to investigations of conical horns. Holzman also showed existence of HOM in exponential horns in the 50's. In "High quality horn loudspeaker systems" this is described as deviation from a simple wave front, both in shape and differences in pressure over the cross section of the horn (or simply the wave) within the same wave period. Commonly, this is known to be an issue in horns with straight or near straight profiles. However, it does also relate to abrupt changes in acoustic impedance, and this is what you typically see in conical and OSWG horns, but it is also something we can have in any other horn type if they start with a significant change in angle compared to the exit angle of the driver itself.
@Robh3606 I forgot to add in my post, that the CD waveguide is not directly the source of this aspect, rather, the common wall angles chosen by the CD designer... one could design a waveguide that has the same or more directivity as the upper HF performance of my horn. The decay of the room and the multiple arrivals caused by it, Blur the transient much more than the difference between those materials in a good design. In the end the higher directivity situation potentially will have the Sharper Transients. This is can be seen clearly by comparing a Be in a wide polar situation to a narrow one. I don't think a good designed Ti or Al diaphragm is going to perform so much worse than Be to overcome this. I know that psychoacoustics comes into play and I don't have that side of things memorized but I do know that decay Mask the low level details, meaning, causes us to not hear them, by over shadowing the low level detail with the decays Spl and that multiple arrivals at the listening position Dull the Transient, not sharpern.
Last edited:
K402 indoor horizontal polar with no gating. Take note that measurements close up like this, end up having a wider beamwidth than what it actually has. But overall polar is otherwise quite accurate down to a certain frequency where the room contributes.
And here's an indoor polar of a horn I used to compare with the K402. It's even wider in the highs, but still sounded considerably smoother, and despite using a less quality driver than used in the K402. So "wideness" in highs is not the issue here IMO. Besides I tested with absorption of early reflections.
And here's an indoor polar of a horn I used to compare with the K402. It's even wider in the highs, but still sounded considerably smoother, and despite using a less quality driver than used in the K402. So "wideness" in highs is not the issue here IMO. Besides I tested with absorption of early reflections.
For those who have an interest. Here's an on-axis measurement of K402 with Celestion AXi2050. This is at 1 m distance and indoor. 1/24 oct. smoothing.
fr does almost nothing tell us about sound quality. Furthermore, the curves are more than disappointing. There is a steep decrease of spl below 600 Hz. The throat region is imo a really stupid design making it easy to manufacture maybe. The surface area expansion of this waveguide is way to fast so it cannot provide much acoustic loading - just learn the math.
Axi2050 attached to TH4001 with a suboptimal adapter. Just recognize the even spl down to almost 300Hz with this much smaller horn. It is a better choice for the AXI.
Last edited:
Here's another measurement a bit closer of the K402 with AXi2050 (black) and vs a horn with a 4" diaphragm (purple). 1/24 oct. smoothing.
Despite that the "purple horn" is using a smaller 4" diaphragm, it loads better in part of the lower midrange frequencies.
Despite that the "purple horn" is using a smaller 4" diaphragm, it loads better in part of the lower midrange frequencies.
Last edited:
Hello camplo
I understand the point you are making but I think it's debatable. You are saying a beaming horn would be beneficial compared to CD in this respect. You are basically saying that the in room ambiance field is going to be so over powering that it will swamp the first arrival, or cloud it so badly that detail will be lost.
Do I have that right?
Are you considering proximity/first arrival?
I have never been in any normal sized room where I could get far enough away for this to occur. In my mind first arrival will dominate.
Even in a large room I can't see anyone deliberately setting up a room of setting up a listening position in room where this would be so.
Rob 🙂
Troy Crowe may AB test the Yamaha JA6681B and the (equalized) Radian 745neobe vs. the B&C DMC50. Any predictions on outcomes? Recommended horns for each?
However, with the Radians, precise EQ and horn combination are obviously critical. Note the experiences of Gary https://www.diyaudio.com/community/threads/compression-driver-impedance-question.318749/page-2 and Pierre https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-764
Last edited:
When have you ever had the contrast to say you feel such a way? meaning.... have you ever used a waveguide with such high directivity in the HF and compared it to something else with a considerably wider HF? I do, but then again, I can't use the same driver. You comment about first arrivals is making me question my stance but for sure the measurements do support what I am saying.
Last edited:
The room you describe is not useful for critical listening with any speaker. Get a nice sounding one without resonances (DE360 for e.g) and as much directivity as the concept alows.
You should give a tweeter like T25B a listen with a chain with lot's of resolution (e.g Hypex dsp amps with digital input). No compression dirver I know can do that resolution and yet natural reproduction. But a compression driver can do WAY more dynamics and is beneficial in a bad room. 2 pretty different use cases, hard to compare.
The room always asks for the speaker. Build a good room and enjoy what a T25B can deliver. In my living room cinema I use DE360 with a horn to get enjoyable music with less room influence.
Hello camplo
Yes in the sense that I have used older horn systems. Here is a picture of a pair of clones I built and still have. One is 4344 the other an Array 1400. The 4344 has increasing DI even with the lens over the 2307 which is an Exponential horn. The 077 has the same basic pattern with a wide horizontal but very narrow vertical pattern,
The Array has an 80 X 80 and a 60 X 30 Biradial CD type horns. I had both in the same room for a while. I built the 4344's first had them for about 5 years and then built the Arrays.
The 4344's were almost head in vise. If you stood or moved off axis you could easily hear the effects of the increasing DI. The 1400's were night and day better in this respect.
These obviously don't and can't use the same drivers. Here is the plot for pattern on the 2307/2308 if you take off the lens the Horizontal mirrors the vertical. As you can see it's gets very beamy up high.
Rob 🙂
Attachments
Does anyone on here have experience, or extended information on this driver btw ?
1" exit, Be truextent dome, with a "plastic" suspension, 34mm Voice coil.
Diaphragm assembly looks rather unique, with the terminal arrangement, going directly through the backcover.
16 0hm diaphragm.
3 slot phase plug it looks like.
And a phaseplug that does not extend to driver exit.
Backcap is very similar to the Radians 745.
External Neo ring magnet.
The air gap looks rather large on the bottom, not nessecearily a admirable trait.
Looks like cutout did not go very smoothly on that pic.
They're E series speakers are also interesting creations, but don't belong in this thread.
1" exit, Be truextent dome, with a "plastic" suspension, 34mm Voice coil.
Diaphragm assembly looks rather unique, with the terminal arrangement, going directly through the backcover.
16 0hm diaphragm.
3 slot phase plug it looks like.
And a phaseplug that does not extend to driver exit.
Backcap is very similar to the Radians 745.
External Neo ring magnet.
The air gap looks rather large on the bottom, not nessecearily a admirable trait.
Looks like cutout did not go very smoothly on that pic.
They're E series speakers are also interesting creations, but don't belong in this thread.
Attachments
Last edited:
The K69 driver that came with K402 horn was of poor quality. Here's a raw measurement of the K69 driver in the K402 horn:
Here's K402 with the JBL 2446 Be in comparison:
K402 horn with JBL 2446 Aquaplas:
K402 horn with JBL 2446 with Radian 1245 alu diaphragm:
All graphs are with 1/24 oct. smoothing. You can see my measurement of the K402 with the AXi2050 earlier in the thread.
The horn rings a bit when I handle it. Less so than other metal horns. Wood, paper, damped metal, etc, is maybe more optimal though I don't sense any obvious resonances occurring when playing audio through the Ciare. I haven't done a frequency sweep to isolate where the primary resonance might be. I think with larger horns and ones which direct lower frequency content, the potential issue of ringing is more of a consideration. I presume any surface or baffle that the horn that I'm using is coupled to reduces any ringing substantially and enough.
Last edited:
You didn't identify the driver used. Did you forget about that?
And you think that I implied that? I didn't.
"Cutoff" is typically only used when talking about certain horn expansion profiles--not the type of horn of interest in this discussion. Loading is another "can of worms" that's usually thrown about--like shadows.
My shorthand use of "acoustic center" here is actually describing the distance from which the measured phase originates--nothing else. If you don't like the term, then use the term that is more convenient for you.
Clearly, you don't wish to examine your assumptions of what causes certain subjective sound quality effects. That's actually the point of my discussion, simply put. You've apparently already made up your mind that it's something that's significant. I simply do not agree.
If you refuse to examine your basic assumptions that I raised above, then I agree--and we have little to agree on in this subject area--and much to disagree on. That's entirely up to you, Mr. Kviserud. Since you obviously don't feel like discussing the subject of the first issue I raised above and instead intend to take a more "at the person" path to try to dismiss it, I guess we'll just have to "agree to disagree" and move on. However, this doesn't engender any additional respect from this side of the discussion, I'm sorry to say.
_________________________________________________________________
For those that may be confused as to just what is occurring here, there are certain people that fully buy into the notion of significant audibility of HOMs (higher order modes) in almost all horn designs, i.e., outside of horns with slots in their throat. And that these significant HOMs color the entire audible presentation of the horn--and we're talking about all horns (except the anointed few designs that have been blessed).
There are also those that don't buy into that notion, based on subjective listening and objective measurements. I'm in the latter camp. Show me a psychoacoustics study that isolates the addition/subtraction of HOMs (only) and their subjective audibility, and I'll certainly read with keen interest--but I don't believe that I've heard it in the type of horns being discussed here (K-402s).
It's audibility of this perceived problem which is at the center of the discussion--and I've not heard it except in perhaps "constant directivity" slotted-throat horns from the 1970s having huge amounts of HOMs that manage to exit the horn's mouth.
The same thing goes for "matching compression driver exit angles" or even "compression drivers must have preferred exit angles" and to match horn throats. Again, show me a study that confirms subjective audibility, and I'll certainly consider it. (I haven't heard it.) Otherwise, I think we're at a standstill--until a rational discussion occurs--instead of rhetoric.
Additionally anyone that says, "Also, I would avoid the 402s without a fix for the throat." says to me they haven't spent much time listening to one. You can see that if one buys wholesale into this "all horns have HOM audibility issues" notion, they couldn't accept the K-402's approach, since its design basically throws cold water on those notions.
Chris
Last edited: