For anyone still following I have remained at 5.3kHz for the crossover point and this sounds a LOT better than crossing higher. I have yet to decide how to try and determine the root cause of the problem. This sounds very good, but is not quite where I expected to end up FWIW. When I have more time and a great deal more energy I will try to figure out what is going on. No 2-way in my future with this horn.
Interesting choice of XO, and based on what I now know about my A290 I think a logical one. I cross at 700Hz and 5.3kHz using 12dB/octave bessel transfer function. I originally used LR24 but decided I preferred gentler slopes and ultimately the bessel. I do use LR24 at 45Hz to cross from my subs to the mains. I am running TAD TD-4001 on the A290s.
Because bluntly I don't like the A-290/TD-4001 HF performance at all. I am not sure the 4001 sounds good above 5kHz either but hard to separate from the horn performance. I am not the only one. (Ask Limono) Looks great in theory and in measurements, in person not so good. I am much happier since I faced that reality.
Despite this, this is definitely the best performance I have heard in my system over the decades, so it is all relative.
Despite this, this is definitely the best performance I have heard in my system over the decades, so it is all relative.
Thanks for the input. In my brief compares between the JBL 2450 H with Aquaplas and a B&,C DCM 8, the B & C sounds a little nicer (somewhat smoother, more relaxed).
This was not with a Yuichi...just an inexpensive plastic wave guide (that I damped with some DynaMat) from Parts Express.
Looking forward to trying it with the Yuichi now that I know the 0 degree exit angle won't be an issue.
So your crossing over the Yuichi A290 at 700 and 5.3kHZ with 2nd order filters and than to another radial type Horn ( 480) from 5.3k up to ?
What super tweeter did you find most effective for your final driver in your four way set up?
Any use of DSP?
I use FaitalPro HF10AK 1 inch drivers on FaitalPro STH100 tractrix horns to cover everything above 5.3kHz. Originally I experimented with crossing at 8kHz and as high as 11kHz. I thought about Yuichi A-1K horn for the tweeters but probably will not proceed.
I use a combination of MiniDSP SHD Studio, RME ADI-2 PRO FS R (AD/DA) and heavily modified DCX2496. Sources are both analog (through the RME) and digital (streaming to the SHD)
Bass is diy Onken bass boxes with Iconic 165-8G
Subs to woofers 45Hz LR 24dB/oct
Woofers to mids 700Hz Bessel 12dB/oct
Mids to HF 5.3kHz Bessel 12dB/oct
This system is pretty complex and it hasn't been an easy journey, the consensus amongst those who have actually heard the system is that it performs pretty well. In the future I have some theories about what is going on with the Yuichi A-290 and I have an Isemcore mic and moto-m4 I purchased in order to step up my measurement game.
I would be remiss if I did not mention the role of room treatment in all of this. It is often ignored/dismissed but my room was a big part of the challenge I've faced.
I use a combination of MiniDSP SHD Studio, RME ADI-2 PRO FS R (AD/DA) and heavily modified DCX2496. Sources are both analog (through the RME) and digital (streaming to the SHD)
Bass is diy Onken bass boxes with Iconic 165-8G
Subs to woofers 45Hz LR 24dB/oct
Woofers to mids 700Hz Bessel 12dB/oct
Mids to HF 5.3kHz Bessel 12dB/oct
This system is pretty complex and it hasn't been an easy journey, the consensus amongst those who have actually heard the system is that it performs pretty well. In the future I have some theories about what is going on with the Yuichi A-290 and I have an Isemcore mic and moto-m4 I purchased in order to step up my measurement game.
I would be remiss if I did not mention the role of room treatment in all of this. It is often ignored/dismissed but my room was a big part of the challenge I've faced.
At the risk of embarrassment sure, and it might provide some hints about what I am struggling with. 
The room is small and very crowded, there is an electronics work area, a small machine shop and this stereo system and a small home theater. I don't know of too many hobbyists who have crammed so much into so little space. No doubt a bigger/emptier space would be a lot better for this system, but a good part of it would not exist were it not for this unlikely space.
The acoustics are not brilliant, but a lot better than you might suspect from the pictures.. Oh, and there goes the last shred of credibility I have..
The bench... There is a 5000 series Pico Scope on top of the RTX which is not really visible.
The room is small and very crowded, there is an electronics work area, a small machine shop and this stereo system and a small home theater. I don't know of too many hobbyists who have crammed so much into so little space. No doubt a bigger/emptier space would be a lot better for this system, but a good part of it would not exist were it not for this unlikely space.The acoustics are not brilliant, but a lot better than you might suspect from the pictures.. Oh, and there goes the last shred of credibility I have..
The bench... There is a 5000 series Pico Scope on top of the RTX which is not really visible.
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Thanks for the pics......very nice.....yes, a bigger space would allow for the system to " breath ", so to speak....however we must use what's available , and you did an admirable job....
Liked the Studer, and Thorens TD124,'s....
By the way do you mind mentioning what specifically you didn't like about the Yuichi A290 and TAD 4001 pairing as a 2 way , that caused you to cut the TAD to 5k ( highs to soft and/or rolled off sounding, or perhaps the reverse...bright- shouty).?
Thanks for posting these....
Liked the Studer, and Thorens TD124,'s....
By the way do you mind mentioning what specifically you didn't like about the Yuichi A290 and TAD 4001 pairing as a 2 way , that caused you to cut the TAD to 5k ( highs to soft and/or rolled off sounding, or perhaps the reverse...bright- shouty).?
Thanks for posting these....
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The A-290 works by far the best with the TD-4001 of the drivers I had tried to date. Detail and imaging are much better than with the Radian 950PB and still significantly better than the "2441."
You can't have missed the foam tubing and the felt adhered to the edges of each horn mouth. There is quite a lot going on along those edges and likely around the throat and vanes of the horns. I think these horns have a serious edge diffraction problem and I have no evidence to prove it.
The problem addressed was what I consider to be an unacceptable level of harshness/distortion (IMD?) above 5kHz when playing any complex program material with a lot of energy in this region regardless of the SPL level. A quick test recommended by Pano to blanket the edges of the horns with towels provided a startling improvement - this is apparently a classic symptom of high frequency diffraction.
Reducing the crossover frequency on a whim to 5kHz resulted in further and what was a rather drastic improvement - I experimented with XO points to 8kHz and found that the problem intensified starting at around 5.8kHz and got progressively worse the higher I moved the XO point.
The abrupt termination of the profile at the horn mouth might be a problem, but I am not really sure. I do think there are other problems, but I have heard similar artifacts with other horns driven by other drivers, but assumed it was my electronics - I kept looking for an EQ solution, sources of distortion etc - there were improvements which I quickly realized improved many other things, but not what I was chasing down.
The TD-4001 has a lot going for it, it is certainly the highest resolution CD I have owned, but that doesn't necessarily make it nice to listen to, and I don't have the answer why. I just know that I don't like the upper midrange and lower treble performance of this combination. I hope to develop a better understanding, but with the lower XO point the performance is in the realm of my expectations, possibly there is a better top than the HF10AK/STH100, but its extended, clean (low thd) and inoffensive sounding.
I'm pretty close to retirement and given the very, very high living expenses here in Boston I don't expect to have the funds to pursue much further improvement in the future so I am resigned to living with the end result of my "mistakes" to the extent possible.
Despite the criticisms above, this is all a major step forward in the sound quality compared to 2440/2380A/T825 that this stuff replaced.
You can't have missed the foam tubing and the felt adhered to the edges of each horn mouth. There is quite a lot going on along those edges and likely around the throat and vanes of the horns. I think these horns have a serious edge diffraction problem and I have no evidence to prove it.
The problem addressed was what I consider to be an unacceptable level of harshness/distortion (IMD?) above 5kHz when playing any complex program material with a lot of energy in this region regardless of the SPL level. A quick test recommended by Pano to blanket the edges of the horns with towels provided a startling improvement - this is apparently a classic symptom of high frequency diffraction.
Reducing the crossover frequency on a whim to 5kHz resulted in further and what was a rather drastic improvement - I experimented with XO points to 8kHz and found that the problem intensified starting at around 5.8kHz and got progressively worse the higher I moved the XO point.
The abrupt termination of the profile at the horn mouth might be a problem, but I am not really sure. I do think there are other problems, but I have heard similar artifacts with other horns driven by other drivers, but assumed it was my electronics - I kept looking for an EQ solution, sources of distortion etc - there were improvements which I quickly realized improved many other things, but not what I was chasing down.
The TD-4001 has a lot going for it, it is certainly the highest resolution CD I have owned, but that doesn't necessarily make it nice to listen to, and I don't have the answer why. I just know that I don't like the upper midrange and lower treble performance of this combination. I hope to develop a better understanding, but with the lower XO point the performance is in the realm of my expectations, possibly there is a better top than the HF10AK/STH100, but its extended, clean (low thd) and inoffensive sounding.
I'm pretty close to retirement and given the very, very high living expenses here in Boston I don't expect to have the funds to pursue much further improvement in the future so I am resigned to living with the end result of my "mistakes" to the extent possible.
Despite the criticisms above, this is all a major step forward in the sound quality compared to 2440/2380A/T825 that this stuff replaced.
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The answer I was able to come up with after discussing it with a friend of mine who also uses the A-290 was similar to Mr. kevinkr's. I think they are surprisingly similar.
Diffraction occurs at the opening of the horn, making the sound cloudy.
In my case, I dealt with the problem in the same way as Mr. kevinkr with the following two points.
1. I made a 4-way crossover with mid-high at approximately 2KHz. The sound of 5KHz is not emitted from the A-290.
2. Affix carbon felt to areas where sound absorption is likely to occur.
Acoustic improvements were more effective at the edges of the horn opening.
Unfortunately, the appearance of the belt-shaped carbon felt attached is not fashionable. It is necessary to consider measures to improve the appearance, but I think it is highly probable that it will remain as it is because the effect is dramatic.
Diffraction occurs at the opening of the horn, making the sound cloudy.
In my case, I dealt with the problem in the same way as Mr. kevinkr with the following two points.
1. I made a 4-way crossover with mid-high at approximately 2KHz. The sound of 5KHz is not emitted from the A-290.
2. Affix carbon felt to areas where sound absorption is likely to occur.
Acoustic improvements were more effective at the edges of the horn opening.
Unfortunately, the appearance of the belt-shaped carbon felt attached is not fashionable. It is necessary to consider measures to improve the appearance, but I think it is highly probable that it will remain as it is because the effect is dramatic.
@santohkun Thank you so much for posting your comments here. I found the improvement with the edges covered startling, but was very embarrassed to share the details because it looks so bad.
The lower XO point makes a big difference and I assume this is due to diffraction in the throat, and adapter and perhaps the vanes as well.
I've gotten used to the look, but I have to admit I was pretty disappointed when I first figured this out.
I may do more in the future.
It seems like the Iwata 300 or Kinoshita horn might have fewer diffraction related issues.
The hardest part of this is that it is very audible and quite difficult or even impossible to measure with the equipment and in the room I have at home - nothing obvious in the measurements. I flailed for quite a while before it dawned on me. I did find the terrible 4kHz resonance in my room. I will probably go hunting for others, although none show in more recent decay plots.
The lower XO point makes a big difference and I assume this is due to diffraction in the throat, and adapter and perhaps the vanes as well.
I've gotten used to the look, but I have to admit I was pretty disappointed when I first figured this out.
I may do more in the future.
It seems like the Iwata 300 or Kinoshita horn might have fewer diffraction related issues.
The hardest part of this is that it is very audible and quite difficult or even impossible to measure with the equipment and in the room I have at home - nothing obvious in the measurements. I flailed for quite a while before it dawned on me. I did find the terrible 4kHz resonance in my room. I will probably go hunting for others, although none show in more recent decay plots.
I suspect you gentlemen have hit on the sweet spot with the Yuichi.....just for grins just lowered the crossover on my DBX Drive Rack to 5000 KHZ ( from 10 k), and the improvements were starting....am using a quasi horn loaded ribbon super tweeter that extends to 40kHZ.
The improvements are quite impressive to say the least.
Do you guys think just adding some self adhesive felt strips to the inside edges at the front opening, without actually wrapping it around to the outside edges will offer any real benefit?
Am somewhat reluctant to lessen the current cosmetics that the Mahogany Yuichi currently enjoys, so not having the edges wrapped would go a long way in preserving the current cosmetic aesthetic.
By the way I notice that the Uber expensive Living Voice OBX- RW, ( 1 MILLION STERLING !), has a similar style horn wave guide as the Yuichi. They don't employ any diffraction material to the edges ( that I can see).
I do believe they also employ a TAD CD in that section of the band pass , however I believe they are rolling it out at 2 kHZ....so perhaps that helps to ameliorate diffraction issues.
The improvements are quite impressive to say the least.
Do you guys think just adding some self adhesive felt strips to the inside edges at the front opening, without actually wrapping it around to the outside edges will offer any real benefit?
Am somewhat reluctant to lessen the current cosmetics that the Mahogany Yuichi currently enjoys, so not having the edges wrapped would go a long way in preserving the current cosmetic aesthetic.
By the way I notice that the Uber expensive Living Voice OBX- RW, ( 1 MILLION STERLING !), has a similar style horn wave guide as the Yuichi. They don't employ any diffraction material to the edges ( that I can see).
I do believe they also employ a TAD CD in that section of the band pass , however I believe they are rolling it out at 2 kHZ....so perhaps that helps to ameliorate diffraction issues.
Point taken......However.....anecdotally there are numerous reports, and some from people I personally know, that have nothing but praise for "What Ever Is Going On" with this design....some have told me if it isn't the best sound reproduction they have ever heard, it's right up there with the very best....
Anyway different strokes for different folks as they say....
Thanks for responding....
Anyway different strokes for different folks as they say....
Thanks for responding....
...corrected the misleading statement. ……
I lowered the crossover point to around 2KHz to prevent sounds above 5KHz from coming out of the A-290. I chose 4-way.