Full-Range Synergy Kit Questions

[chrapladm]

Is there an intended budget thought of yet?

My idea was along the lines of a SH64/96 for my build. Not the cheapest option but I dont mind the wait. I do like the size of the SH64 the best for my wants thought.

Not sure how I missed seeing your 402 MEH build. I havent been on ALL the forums in quite a while now so I could have easily missed it. That would have been quite amazing to see and hear.

And regarding a cheaper option I would just build what SpeakerScott, I think, made years ago. I believe he used Dayton 10's on his build. I should have built that in the past but never got around to it.

 

[BWRX]

I'm not seriously considering a DIY Synergy system at the moment, but am always interested in learning about new technologies and implementations.

1) What common compression driver(s) and woofers would you most want to use (brand and model) in a kit?

Doesn't matter as long as it sounds good! A high performance/price ratio is obviously desirable.

2) What is the lowest crossing frequency (i.e., "fc") that you would want out of the loudspeaker?

Around 100Hz because it must crossover to a typical sub.

3) What maximum size would you be willing to build/buy for your listening environment?

The absolute max size (and this is probably pushing it) for each speaker would probably be around 36in wide by 24in high x 24in deep. It would be a stereo pair of speakers.

4) How much would you realistically be willing to spend per loudspeaker to make them from a kit?

Probably around $200 for a pair of enclosures without drivers, maybe $400 for a pair including the drivers.

5) Would you be willing to use an active crossover instead of passive?

Probably, as long as the active solution could be modified/reused for use with other systems.

 

[chrapladm]

Would be great if there was an ala carte style so you could add what you were using and the panels would be made accordingly.

 

[Cask05]

Is there an intended budget thought of yet?

Budget for a total kit price, or budget to build the pieces which produce a kit?

Due to the nature of the questions posed at the top of this thread, I don't have a kit price yet. What price ceiling would you consider for a kit?

Not sure how I missed seeing your 402 MEH build. I havent been on ALL the forums in quite a while now so I could have easily missed it. That would have been quite amazing to see and hear.

See the K-forum thread.

 

[chrapladm]

For me its hard to even say a price because shipping costs end up doubling the price. Some of the speaker kits available now I would have bought but add in shipping and it gets too dear.

SO thats why I mentioned ala carte. I would use things I could get easily here in my own country.

For in the USA I think a reasonable kit would be maybe 500. BUT thats with no consideration at all of anything. Once you figure in a few things maybe that number goes up.

As I said SpeakerScott's build is a great example. Uses Dayton 8's(I was wrong earlier) and other parts for not a LOT of coin.

Here is Scott's amazing build. If shipping wasnt as bad as it is I would build this for indoors. I just happen to need something for outdoors like the SH64 also.

http://www.diyaudio.com/forums/multi-way/244890-synergy-horns-dayton-prv.html
SO this is what I would base a kit on. Or at least something similar with available parts.


Thanks for your link also.

 

[Cask05]

...I've never heard horn bass for the lowest octaves so perhaps I'm wrong about this.

So you've not heard a Khorn, La Scala, Belle or Jubilee.

Perhaps I should explain my position on this subject. I think that part of the issue with a full-range MEH is awareness of the effects of horn-loaded bass on hi-fi reproduction. This is a well-worn topic of conversation on at least one forum. Once you've heard it (and you already have a good concept of what acoustic--not amplified--bass and percussion sounds like) then I find that virtually everyone prefers its clean, crisp sound. This is the proverbial "legit musicians prefer corner horns" story. The sound of a slamming car door sound just like the real thing, while direct radiating drivers overemphasize and overshoot the actual sound. The following excerpt was taken from a noted review of the Klipschorn in 1986 by Richard C. Heyser:

Many years ago, when listening to a...pair of Klipschorns, I decided to find out how accurate the low end was. So I placed two high-quality condenser microphones outside my house, in a location where I could listen to the sound they picked up while viewing the same microphone location through a picture window that stretched between the two Klipschorns. It was only a matter of walking outside and listening, then walking inside and listening to compare the reproduced sound with reality. I could also switch between the K-horns and a pair of excellent speakers whose bass could shake the house on pipe organ; they made the K-horns sound thin by comparison.

Then a funny thing happened. The sound of a slammed car door sounded like a slammed car door on the K-horns, but sounded like muffled "whumps" on the "wider range" system. The same with helicopter fly-overs (quite frequent where I used to live) and with the sound of distant traffic.

I never forgot that experiment nor its ear-opening ramifications with regard to sonic accuracy versus measurement. Quite true, I have listened to many excellent subwoofers that could shake the walls at 10 Hz, while the K-horn produced little sound pressure even an octave above that frequency. But in my personal opinion, accurate, percussive bass is a specialty which a properly set-up corner horn seems to have to itself.

To skip to the end of that conversation--for me, the sound of good horn-loaded bass hasn't been duplicated by any direct radiating woofers, either in vented boxes or closed box/acoustic suspensions. The includes up to 4x15" woofers in a large vented box.

In my experience, slot loading is only intermediate to horn loading in terms of effect on the sound--a consolation prize.

Note that as a point of departure, the K-402-MEH loads to the same low 31 Hz point as a Khorn bass bin when placed in a room corner. Against a wall, it easily loads to 40 Hz. It holds its polars so well that it doesn't benefit from being spaced away from room boundaries--in fact, it benefits greatly from boundary gain.

Chris

 

[AllenB]

It's apparent Richard found this out for himself but he hasn't made it clear whether the solution itself was a horn, a room corner or the resulting distributed pressures? Corner placement can help here and the response must be fairly correct, (to reproduce such wideband effects as a car door, separating the clink of the striker from the tactile feel of the weight of the car so it can be recognised without any thought processes).

The corner gives a location from which a source can launch a wavefront that can remain relatively undisturbed for several milliseconds before beginning to achieve room sized expansion and direct listener sound without yet reflecting. Question: If you create a woofer corner source based on a closed box, yet build it properly matching the floor and two side walls to guide it out, do you call it a direct radiator? Would it sound good?

 

[Soldermizer]

The pre-built option...

Hardly a new idea but why not buy (or consider the parts list of) the Yorkville Unity U15? This is a true Unity design, been on the market over ten years, maybe 20? Brand new they are $1400 each or less. For this you get a fugly but durable PA cabinet with a 15" conical horn comprised of a

BMS 4550-OEM compression driver "tweeter"
3x Celestion 5" mids
1x 15" 18Sound woofer

Yes, it is designed for PA use which means loud and not very low bass. If you were able to find a "parts or repair" used pair for (say) 1/4 the price new, and bypass the crossovers (which were blown anyway), and actively EQ them, you might have a nice pair of Unity. Which is exactly what I did.

I still applaud efforts to offer a flat pack version. We've been waiting what, 15 years?

 

[nc535]

Question: If you create a woofer corner source based on a closed box, yet build it properly matching the floor and two side walls to guide it out, do you call it a direct radiator? Would it sound good?

That is exactly what I've done in "My Synergy Corner Horns and Bass Bins. Well, not exactly - I'm only using the two side walls to guide the sound out, not the floor. I think it sounds good. I think I'll get my subs out of storage some day to support it below 40 Hz for HT but I'm not in any hurry to do so.

I haven't heard Jubilee or K-Horn or LaScala but I have studied those designs down to the level of Horn Resp models and drawing my own Sketchup models. I went with a sealed slot loaded woofer with corner gain would give me more extension than a horn path that nominally that shows loading down to 60 Hz at best, IIRCC. That is interesting because that is about the same point where my TD15Hs start rolling off and sealed boxes roll off less quickly than a horn below cutoff. TD15s are relatively high excursion compared to what typically is used in that kind of horn, which is designed not to need much excursion, above cutoff anyway.

I think that the 15" woofers on the sides of the Cask MEH are acting essentially as sealed woofers. I don't see the horn as deep enough to provide much benefit down below 60 Hz. Corner gain in spades but only down to where the room walls become transparent to the bass which in my house is around 35 hz.

 

[hollowboy]

If you want this thread to be a rehash of 3-way MEH kit threads, then I suppose you could simply answer with that kind of thinking. However, that's not what I'm planning.

I think you should make the 2-way thing explicit in post 1.

I've been using 1.4" and 2" compression drivers on K-402 two-way Jubilees for almost 10 years now--crossed at 400 Hz and extending up to 16-18 kHz, whose performance is spectacular, IME.

"spectacular" sounds good.

Why not make a kit that is basically a postage-friendly clone of your home system, so that people in other countries can enjoy them too?

But you can answer in any way that you wish (short of feeding trolls, of course)...

My answer:

Assume people want exactly what you want - a hacked 402 (or similar), and simply make it easy for them to get it.
https://community.klipsch.com/index.php?/topic/161404-a-k-402-based-full-range-multiple-entry-horn/

Assume people will use active crossovers and can spare a few dollars for a basic measuring mic.

I'd rather get a $100 mic to measure + tweak my crossover to work with my room and with locally available drivers, than spend $1000 extra on shipping + taxes for the 'official' drivers.

Therefore, I'd suggest offering the kit as a flat pack of ply + a few bits of cast steel (or plastic):

-4 big triangles of ply per horn (with screw holes pre-drilled & woofer ports pre-cut)
-A throat section that mounts the CD and covers the round-to-square transition
-Corner sections (simple L - shaped brackets)

...so the kit builder would just need to screw the brackets & throat into the ply to get the horn shape, then run a bead of glue over the joins to make them airtight.

I'd suggest leaving off the ply for international orders - just sell the cast parts and a detailed plan for cutting the wood.

POINT BY POINT:

5) Would you be willing to use an active crossover instead of passive?

Yes. Just assume this.

4) How much would you realistically be willing to spend per loudspeaker to make them from a kit?

For the most basic cast parts + cutting plan version, about $250.

3) What maximum size would you be willing to build/buy for your listening environment?

You could sell a couple of different sizes. Just make the ply triangles different sizes.

For the most basic cast parts + cutting plan version, the end user could decide for themselves - they'd make the horn bigger simply by cutting bigger pieces of ply.

2) What is the lowest crossing frequency (i.e., "fc") that you would want out of the loudspeaker?

See above answer; end user decides

1) What common compression driver(s) and woofers would you most want to use (brand and model) in a kit?

See above. Have a list of recommend parts, but don't make anything mandatory.

 

[Cask05]

It's apparent Richard found this out for himself but he hasn't made it clear whether the solution itself was a horn, a room corner or the resulting distributed pressures? Corner placement can help here and the response must be fairly correct, (to reproduce such wideband effects as a car door, separating the clink of the striker from the tactile feel of the weight of the car so it can be recognised without any though processes).

The corner gives a location from which a source can launch a wavefront that can remain relatively undisturbed for several milliseconds before beginning to achieve room sized expansion and direct listener sound without yet reflecting. Question: If you create a woofer corner source based on a closed box, yet build it properly matching the floor and two side walls to guide it out, do you call it a direct radiator? Would it sound good?

I'm not sure that a lot of people really understand what is required for corner-horn loading to achieve what Dick Heyser was saying. You can place a direct radiating woofer in a corner and get significantly reduced cone motion for a given output SPL--corresponding much lower modulation distortion and even lower group delay. PWK wrote on that too, several times. Yet he wrote that he didn't like to put a DR woofer between two corner horns because of the perceptibly higher distortion. I agree with him, having done that in my room over a period of years using various combinations of DR and then horn-loaded woofers.

It's not close. The DR woofer will always be a DR woofer however well you corner load it. I see this a lot--the tendency to immediately discard the idea of corner or 1/4 space horn loading in favor of DR by picking apart descriptions and assumed causes. Heyser and PWK are saying something entirely different than the assumed separate effects that you mention. What they are saying is quite audible to my ears and really isn't dismissible due to assumed contributing causes.

One thing that I've found however is that the horn in boundary loading must have a large enough mouth to control polars below about 200 Hz in both axes and that vented (bass reflex) loading is avoided--thus pointing to group delay as a contributing culprit. The efficiency of the horn's handover to boundary loading is the real enabler in my experience. That's why the Danley SH series multiple entry horns and the K-402-MEH both load to significantly below their calculated 1/4 wavelength point by using room boundaries-always loaded to a higher acoustic load resistance level than DR woofers in boundary effect. PWK wrote on this too at great length. I've found that it's the size of the horn's mouth and the use of straight-sided horns that enable boundary-based extension of horn loading in corner or in 1/4-space effect.

Many people seem to want to immediately discard that notion (boundary loading) out of hand. I use my ears: every time they choose horn-loaded bass.

YMMV.

Chris

 

[nc535]

Hi Chris:
Well that was my hypothesis - that sufficient DR cone area would make up for horn gain. It works on paper but the ear is the ultimate judge.

I've demonstrated my belief in corner loading and it occurs to me that the only way I'm going to get the two 15" woofers per side into a corner that I originally planned without going uncomfortably or even dangerously tall is the way you propose. So I am amenable to a 2nd go at a corner synergy.

Controlling polars below 200 Hz vertically? That is one thing I wish I had paid more attention to, despite the increased size.

Efficiency of handing off to boundary loading? Well if you design it for the corner you can just about seal it against the walls and the floor for the ultimate coupling. The listener is then inside the horn and if my system is any indication, he will feel he is inside the drum on percussions.

Jack

 

[Cask05]

Hardly a new idea but why not buy (or consider the parts list of) the Yorkville Unity U15? This is a true Unity design, been on the market over ten years, maybe 20? Brand new they are $1400 each or less. For this you get a fugly but durable PA cabinet with a 15" conical horn...

Certainly, if you've gone that way yourself and advertised over the time period that you've stated, then I assume that those that have that bent would go that way. It's certainly a valid path.

I still applaud efforts to offer a flat pack version. We've been waiting what, 15 years?

I believe that this is what Bill Waslo was facilitating with his "Synergy" spreadsheet, and I certainly wouldn't want to cover his efforts. Perhaps someone that has built his CoSyne might be up for a "flat pack", i.e., something built entirely of MDF or wood. I also believe that his spreadsheet and Hornresp are good tools to expand the size of the CoSyne design to be truly full-range, i.e., without need for a separate vented DR bass cabinet to be integrated with the MEH. That option has been on the table for at least 3 years now since Bill released his spreadsheet. However it seems to make less sense in this case since shipping MDF in a package would be more expensive than buying locally and cutting yourself--assuming that the cuts are simple.

However, since my extensive youth woodworking experiences with pine and MDF glue and associated headaches, I'm really not that much into cutting particle board/MDF or plywood for horn materials and shipping them...for fun.

But constructing a horn that does the MEH job in one piece that performs significantly better than a dual flare straight-sided horn in terms of polars and its associated listening performance--and potentially much stiffer--is a lot more attractive to me. Boxes can be built and drivers bought locally, or al la carte in selectable kit add-on fashion. I suppose that's also true for the passive crossover crowd, but I see increased interest in actives here...which really encourages me since MEHs are tailor-made for active crossover use.

Personally, my motivation is much improved hi-fi performance by improving the low frequency capabilities of the typical MEH designs found on this forum--without adding distortion (group delay, modulation, compression, lobing, etc.). Single point performance down to a lower frequency with a stiffer horn is my current focus. Doing that in a way that's useful and shareable with others, too, is also of highest interest. Hence this thread. Otherwise, I'd be spending my time elsewhere.

I'm still listening, however. If there are new ideas in cutting up and assembling plywood packages that might change that equation significantly, I'm certainly interested in hearing them.

Gauging interest in narrower coverage angles for the horn is one of the driving reasons why I posted the thread. I personally find that 90 x 60 degree coverage really increases the listening envelopment and soundstage, and increases the size of the listen position area quite dramatically to cover the entire room to within a metre or so of the loudspeakers' mouths. Going to a smaller coverage angle cranks down on those two areas of performance, in my experience. But I've seen people with what I would consider really small listening rooms (less than 12-14 feet or 3.6-4.3 metre laterally in width or length) that would benefit from the reduced coverage angles to reduce early reflections. This, to me, is a real fork in the road in terms of designing a kit.

Chris

 

[chrapladm]

Well I look forward to seeing how this goes. I am going to be using not the traditional items in my horn. BUT I have always wondered about doing a straight like horn myself. Multiple layers and maybe CF clothe for the finished look. But I would be prototyping in MDF to make sure I have everything correct.

I was thinking of a 60 x40 pattern or even a 80 x 40 pattern. BUT it really would just depend on this kit price and other costs. For indoors I would be up for a 60 x 40 pattern. For outdoors I was looking at 60 x 40 also. That being said I could use a whatever pattern length for outside.

13ft wide room seems like a 48" wide speaker might not be doable 90 x 40 SH96. Thats why I always looked at the 36" wide speaker for my living room. It would be 60 x 40 but I would use the same speaker for outdoors also.

Any idea of the construction costs of a fiber glass horn or whatever material your thinking?

I looked at buying horns from Volti Audio years ago but the shipping for a pair of 300hz horns was more than double the price. BUT in saying that a pair of SH64's were about 1200 to ship. So I am curious what kind of size these end up being. If Danley sent me a pair of horns for shipping costs only and I had to pay for the parts on my end I would be ok with that. It would be a very slow build but still I think doable and worth the money to me.

Really just depends on budgets. Most people dont like to spend money. I didnt buy the Spencer SH that Paul made here in OZ. I didnt feel it was worth the money. PLUS I looked at just going back home and buying some older model Danley's for less money.

Even selling mould kits to make the horn itself out of "X," material would be a big help. So I think your on the right track. Would just have to narrow down a size for your kit and go from there. I think if you had a great setup yourself and showed everyone how to do it and sold different versions of a kit then that would be a winner.

Most people are not going to know what works and what doesnt component wise. SO 60 x 40 sounds like a great pattern also. That can cover most living rooms very well.

 

[Cask05]

...So I am amenable to a 2nd go at a corner synergy...

Efficiency of handing off to boundary loading? Well if you design it for the corner you can just about seal it against the walls and the floor for the ultimate coupling. The listener is then inside the horn and if my system is any indication, he will feel he is inside the drum on percussions.

Jack

Thanks Jack. I really appreciate your comments (as well as everyone else's here). I read each posting closely and evaluate what I'm reading. These discussions are sometimes difficult but we seem to have escaped much of the "gnashing of teeth" phase.

I find that discussing low frequency horn performance has to date been a dividing subject on online forums for reasons that I can't fully enumerate here. I'm not really into "hard and fast" positions (surprisingly), but I do intend to convey my prejudices and experiences even in the light of going counter to the commonly held assumptions on the subject--which I've largely addressed thus far. I'm not new to this, so I've got views, too, and they might not align closely with all responses.

Realization that boundary loading always comes into play at low frequencies (in home environments, at least) and larger mouth sizes are required for good low frequency performance--these are two areas that seem to be much less widely known among LF horn practitioners. It's difficult to ease into those discussions or to address them head-on , and this is the most successful thread in that regard that I've either seen or participated in thus far. So in that light, I'm actually extremely encouraged.

So the issue of a full-range MEH kit first seems to come down to:

1) the horn itself (and associated user biases on mouth sizes and room placement), followed closely by,
2) the room dimensions and acoustic properties that they're going to be used in,
3) overall cost constraints, and
4) listener preferences.

If a statistically significant set of inputs can be generated here, that will guide me and influence my thinking most strongly.

I also know that it is probably unusual to talk about requirements and desirements first instead of design solutions on a forum like this, but I've found that eliciting needs first is a much more important activity, and one that others might multiply use for their own at-home DIY implementations and/or kit build activities if they disagree with the direction that I go.

Chris

 

[Cask05]

Any idea of the construction costs of a fiber glass horn or whatever material your thinking?

...Really just depends on budgets. Most people don't like to spend money. I didnt buy the Spencer SH that Paul made here in OZ. I didnt feel it was worth the money. PLUS I looked at just going back home and buying some older model Danley's for less money.

Even selling mould kits to make the horn itself out of "X," material would be a big help. So I think your on the right track. Would just have to narrow down a size for your kit and go from there. I think if you had a great setup yourself and showed everyone how to do it and sold different versions of a kit then that would be a winner.

I don't know yet what the per-horn material costs are going to be. I do know that the weight of the horn is going to be sized to something more substantial than a K-402 (two versions currently exist: the older compression molded version is 25 lbs, and newer injection molded version is 15 lbs.) in order to minimize deflections and resonances - due to the addition of the dual 15" woofers providing about half the audible octaves over the K-402's regular duties. I'm thinking the horn structure itself (without drivers and box) will be in the 40-50 lbs. region...compare to that of a Khorn or Jubilee bass bin...but it could be lighter when all is done. Fidelity comes first, and that means high stiffness and absence of resonances.

I know about the money thing: there seems to be an inverse relationship between number of posts that someone makes on a forum and their disposable income . I ask about money in my question set simply because I don't want to be 10x out from what people say they will spend. The rest is pretty complex to get to a real price that people will really line up to pay.

I also find that there are a subset of posters on typical forums that are very vocal but usually buy next to nothing. Fear not: I know how to identify and handle those issues--as that was a large part of my job for many years. There are many more DIYers that don't voice their opinions, but which buy the finished product.

The "ship a mold to country" concept you mention is something that would have to be handled like a business transaction or perhaps like a franchise arrangement with minimum stipulations on product/service quality involved. And not because I would want it that way but because the cost of the molds are measured in thousands of dollars (US) each set. I'm personally willing to spend that to get what I need for 3-5 horns in my setup--and there's an interesting story of why that is so, that is buying horns from present vendors and modifying them for purpose. But most people here aren't willing to do that. Also, the appearance of the horns wouldn't be a controllable factor in the buy-and-modify approach due to the "take it or leave it" attitude of present manufacturers intent on maintaining a minimum profit margin and not being bothered by customizations. At any rate, this all gets pretty complicated pretty fast.

First things first. Getting design requirements right (including price) is the job at hand. Holding horn costs down is a threshold issue - above a price threshold, few are sold, and below the price threshold, many are sold. The objective is to "design to price". This is also something that I did for years in a prior life so I'm really not concerned about attaining the objective.

Chris

 

[AllenB]

Well if you design it for the corner you can just about seal it against the walls and the floor for the ultimate coupling.
Jack

The options are limited to those that can be terminated that way. Your only choice is whether to use the available walls as surfaces, or as the whole horn (an important choice for given horn types), if you find something that fits. Eg. Tractrix/LeCleach require free space to terminate into to be reflection free. They can use surfaces to divide the horn but they require continuous opening. Hyp/Exp types are unto themselves, as in they can work with surfaces but don't fit into volumes.

he will feel he is inside the drum on percussions.

Maybe this fits in with the discussion on reflections after the source..

 

[nc535]

I suppose I should answer the poll questions

1) What common compression driver(s) and woofers would you most want to use (brand and model) in a kit?
I'd love to use the new Celestion Axidriver 2050 as I think that could be a game changer but not sure if/when it will become available to DIYers. If not that then what? I'm not familiar with anything but the high end choices and not enthusiastic about spending that much money. What should I be looking at? And, while on this subject, what about beaming and breakup at HF from a 2" driver?

On the woofer side, I already have 4 AE TD15Hs that I would hope to use. They model well on conical horns.

2) What is the lowest crossing frequency (i.e., "fc") that you would want out of the loudspeaker?
If it doesn't go down to 35 Hz, its not full range but I would expect to use EQ to get there.

3) What maximum size would you be willing to build/buy for your listening environment?
I just modelled 52" by 33" by 24" deep in my corners which was a 90x60 2 segment conical with horizontal pattern control to 175 Hz. That is almost 2x what I have now. That looks fine but a third one in the center would be too much. Would have to scale it back or do something different for the center; would only need 100 Hz lower XO for there.

4) How much would you realistically be willing to spend per loudspeaker to make them from a kit?
I'm not particularly cost driven so long as its reasonable but I will be an ala carte purchaser rather than a full kit purchaser. A one piece horn that meets these requirements is worth $hundreds and any kit purchaser should expect to be helping to amortize the cost of the mold. But paying hundreds for the horn and hundreds more to ship may be a deal killer for some. Being able to ship economically may set a maximum size - I think UPS has a maximum box size; don't recall what it is.

5) Would you be willing to use an active crossover instead of passive?
Already equipped for active; no interest in passive.

 

[AllenB]

It's not close. The DR woofer will always be a DR woofer however well you corner load it. I see this a lot--the tendency to immediately discard the idea of corner or 1/4 space horn loading in favor of DR by picking apart descriptions and assumed causes. Heyser and PWK are saying something entirely different than the assumed separate effects that you mention. What they are saying is quite audible to my ears and really isn't dismissible due to assumed contributing causes.

It takes a certain class of woofer to meet these needs. Eg. thermal compression is revealed in all its negative glory when everything else is so right, otherwise it is just another problem. The level of prioritisation of harmonic distortion is questionable. It can be dealt with in other ways.

 

[Audiodidakt]

On the woofer side, I already have 4 AE TD15Hs that I would hope to use. They model well on conical horns.

According to the producer these aren't the best for horn applications as compressed air will escape through the gap between the phase plug and the cone. How much of a problem this really is I do not know.

Best regards

Gisle