What is the best tweeter

Matthew J Poes

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as a way to break off our discussion around tweeters, I am creating this thread.

As I noted before, I had some bad experiences with the folded air motion tweeters and walked away unconvinced it was anything special. I don't feel that Domes are for the proletariat. Instead I generally feel that tweeters are a commodity and that there are good and bad of all. That the final product is what matters, with equally good results being possible from all technologies.

Which isn’t to say that certain tweeters don’t have advantages.

My own speakers use compression drivers. Their advantage are that they optimally mate to a waveguide minimizing diffraction and reflections in the mouth, produce a phase coherent spherical wavefront, and are very high power and sensitive. There negative is that they require a special phase plug to create that wavefront and it necessarily puts a limitation on the upper end of the response, as does the dome or ring radiator, which is often much larger than other tweeters. As such, few produce out to 20khz and beyond. Arguably not audible, but a limitation.

Ribbons are cool, the light diaphragm allows for reproduction of highs to very high frequencies. They have low distortion when operated within their linear range. When designed right they have very wide horizontal dispersion but well controlled vertical dispersion. Their cons are that they can’t reproduce lower treble without being very large. Additionally, they need an expensive transformer which can impact sound quality. Finally, they don’t handle much power and are known to be easy to blow. I’m reviewing a speaker with a true ribbon and the designer conceded I need to be careful.

Dome tweeters are probably the most ubiquitous tweeter type. They are great! Designed right they can have a very wide bandwidth, good dispersion, and low distortion. Additionally, few tweeter types have a smoother response than the humble dome. Material type can matter, but I’m not convinced a particular material matters as much as it’s implementation. The new Beryllium dome tweeters from Scan Speak, Seas, and Satori are all amazing standout performers. I’ve also recently fallen in love with speakers that use Berrylium. I've heard some argue that titanium and aluminum, silk, ceramic, etc. can all achieve equally good results. Their negative, they don’t have well controlled dispersion and tend to beam at high frequencies. As such the directivity changes at some point, usually around 10khz. This can lead to the speaker sounding a bit dull or lacking extension in room if too severe. They also don't handle a lot of power usually. They didn't used to be very sensitive but that has changed.

Planar: well this approach allows for a large surface area that can control dispersion well. They operate by virtue of a printed or adhered voice coil on a light film diaphragm placed within a magentic field. Like ribbons they tend to have unusually low distortion and an ability to extend to really high frequencies. Their negative is that they often don’t have the flattest response. You either accept a lot of garbage or use them over a specified bandwidth. Not all are created equal either. B&G makes some pretty good ones. These tend to distort when you get too low in frequency in a more abnoxious way and have not always been the most reliable. I rebuilt close to 100 classic Infinity Emit tweeters in my day, I’m only 37!

Air Motion transformer: this approach is said to allow a large radiating surface area and often they can extend very high in frequency. They are a lot like a Planar in operation, but instead of the enter diaphragm moving in and out, it compresses and expands like an accordion. They can be built to shape the wavefront so at least over a given distance they aren’t spherical, and can be built to be both efficient and robust. But like I said, they are still a commodity product. There are good and bad versions of all these designs. And...there seem to be a lot of bad Airmotions on the market.

So I don’t dislike airmotions because they are inherently bad. It’s because I have seen a lot of bad ones and it seems like good ones are quite expensive. I know RBH feels the same way and had to use a very expensive air motion tweeter to get one that met their expectations. And it’s my understanding that they use it instead of beryllium domes because it’s almost as good for a lot less money, rather than better.

My view remains that it is possible to achieve good results with any tweeter design. The design is less important than how it performs and how the designer implements it.

Now let’s look at some Voicecoil test bench measurements for examples of good versions of all designs:

Let’s start with a Satori Beryllium dome
BEAB568C-DE92-4DD5-B3EB-422F37B4BFDF.jpeg

And distortion
A6C9FE6E-B750-4DCB-AF98-E943403E6924.jpeg

Not bad. There are some problems up high, but very high Q and likely not audible.

How about a ribbon (Tnagband)
3D41C1EC-96CE-4CC0-902B-A319625C2A5E.jpeg

B5C395DE-C83C-44BE-9829-7216F838CFDC.jpeg

Look at that dispersion and extension. Doesn’t get much better than that (if your goal is wide dispersion). Distortion is not bad, but you can see that it must be used with a high crossover. This ribbon is small, but then, it’s still much larger than a 1” dome tweeter that itself could operate far Lower.

How about a good CD (18 sound 1.4” model, HF garbage is largely dictated by the horn or waveguide and may look different on a better one):
4ED87AD7-6C8E-43BA-A1EF-43E9F27D3D51.jpeg

1DECEAB4-464C-435D-96F2-C773C3AB4422.jpeg
As you can see it has a good flat response with very good directivity control. Better than any other design so far. It’s distortion is silly low. More amazing, look carefully at the drive level. Pro drivers are tested at far higher levels than consumer drivers. This tweeter can play far louder than any consumer tweeter can dream of with no distortion. Obviously the really Hf stuff is a little messier than the ribbon, but again, this is completely waveguide dependent. Even the measuring distance matters here. It’s caused by reflections in the waveguide. Other designs don’t have this problem and it’s not as audible a problem as it looks.

How about a Beyma Air Motion:
8303FBAC-F188-4392-9EDB-81E59DA47CC0.jpeg
It’s not terrible, but i think the others look better. Most of its worst problems are near or above 20khz. It does beam quite a bit worse than the others.

372B4BA9-B5F0-4A60-AB67-0A12C1FD51C0.jpeg 923E182C-680B-469C-BE79-F3FBBBEB9800.jpeg
Here is the waveguide loaded version. For this one, I honestly don’t see the point. The response doesn’t look good. I don’t see a great advantage to this driver. It has a bad diffraction artifact at 15khz and doesn’t have the best directivity control. It is possible that with the right crossover it would achieve good results. It’s very likely that bad stuff at 15khz isn’t audible.

Distortion isn’t as bad as it looks. Look at the scale, it’s mostly under 1%. It’s also not better than other designs however.

So what else could be it’s advantage? Well a common view is that they are simply a more deft tweeter that store less energy and sound cleaner. Maybe? We saw the distortion was no better and response worse than other deistns (but again it’s totally a workable response). So let’s look at CSD:
373AAD87-76D2-498A-80B0-42E502CC9A2F.jpeg
So that is pretty good actually. It stores very little energy. It’s on and off like a switch. Just a bit of stored energy at maybe like 3khz and very low in levels. So this could be a legit Claim.

Here is another Airmotion CSD:
333DA6EF-2FE8-4157-ABC1-9C7A87703A85.jpeg
Again looks good. Not as good, but very good.


Here is a B&C compression driver, not as good but still good. Stores energy at 1-2khz. I believe that this may be somewhat waveguide dependent because it seems they are all over the place.
9DD08DE3-309D-4F59-9CA6-D4228734B478.jpeg

Here is that 18 sound which has a big 1.4” opening and 3” diaphragm. It also had a huge waveguide so I suspect this energy storage is characteristic of such a big system.
392958BF-6D22-4E18-BF34-4CB20A0C88AF.jpeg
Pretty good all things considered but clearly sorting more energy than the others.


Here is that Satori Dome tweeter

0E5E1C30-F014-4CDE-B8AE-F389502845A3.jpeg
A bit more energy initially but absolutely no ringing. It’s good.

One last thing to make my point:

Look at this set of measurements.
068FB860-9FEB-496F-A5AB-3AF55A930FAC.jpeg 3DD22DEF-ACF4-4953-A7E6-7358CD774AFF.jpeg 15F716CD-88F4-45EC-BC6F-357CE5BF1E92.jpeg

I think that looks really good. It does some things better and some things worse than other designs. As a whole I see nothing there to tell me it’s a lesser tweeter. That is a relatively cheap Wavecor silk dome tweeter. It even extends well past 20khz!

Now what was my own issue with the airmotion? Without naming names, I had some sent to me as samples to test. I won’t get into how or why, but needless to say, they ranged in price and quality but all came from the same Chinese manufacturer (who actually makes most of the Chinese built AMT’s for most companies).

One of them had poor QC and the pair I received measured differently. It had a buzz and distortion in one of the devices from bad riveting.

All displayed comb filtering but it seemed to dissipate with distance. I think the front plate causes it.

The large ones could be crossed low, below 2khz, but they were as big as a good waveguide that could cross a full octave lower. And they couldn’t extend smoothly past 10khz. They had a very irregular response. I figured it might work better as an upper midrange or lower treble driver. But then, what are making, 5-way speakers?

The medium sized ones were ok. Could cross around 2.5khz and had a workable response to my upper measurement limit of the time. They had high distortion if driven hard. Like they became non-linear quick. I found you would need to use high order crossovers or cross much higher to avoid the problem.

I ended up killing two of them in testing. I’ve never killed a tweeter in testing other than a ribbon once.

So I was left feeling like the AMT was fine but nothing special. That other drivers might offer advantages i prefer. I think because they are so hot I’m more sour on them given this experience. If it was treated like what I think it is, just another means to an end, I probably would be more forgiving.
 

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JStewart

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Wow! Great comparison between the different technologies. Thanks!

Could you tell us how many degrees the off axis measurements were taken at?

Instead I generally feel that tweeters are a commodity and that there are good and bad of all. That the final product is what matters, with equally good results being possible from all technologies.
Seems true much of the gear in our hobby. Proper use and implementation make all the difference.
 

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Thanks Mathew, as usual great information and well written.
So my EVs have an odd ball tweeter and really stand out as unusual for a design.

EV sentry 500.jpg
They use what I believe is a 2" "super dome tweeter" that can handle up to 25watts but it looks alot more like a horn tweeter of sorts. They even implemented an acoustic foam filter that sits in front of it to flatten the response on it. It still really falls off above 18K but Ive never notices any lack in clarity or quality.

Full specs here http://mypicsonline.net/archive/archives.telex.com/archives/EV/Speakers/EDS/Sentry 500 EDS.pdf

My question is how do they keep this speaker so flat for response with only a 2 way design using a 12" woofer and tweeter combination. .
 

Matthew J Poes

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Wow! Great comparison between the different technologies. Thanks!

Could you tell us how many degrees the off axis measurements were taken at?



Seems true much of the gear in our hobby. Proper use and implementation make all the difference.
Yes, Vance takes those at 0, 15, 30, and 45 degrees. Corse but representative.

The 0-25 degrees reflects the direct sound response of a speaker. So once that tweeter is used in a real speaker, the 0, 15, and 30 degree plots, averaged, give you a close approximation of the in-room listening window response. Note that 30 is actually a little far out.

The first reflection response would cover data we don't have here, its 40, 60, 80 in the horizontal, and 50 degrees in the vertical (all plus and minus).

So there is a good argument to be made that if the tweeter looks bad at 30 degree or even 45 degrees, that this might in fact impact the in-room listening window response. If the speakers response falls apart past 30 degrees, then the first reflection response will also fall apart.
 

Matthew J Poes

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Thanks Mathew, as usual great information and well written.
So my EVs have an odd ball tweeter and really stand out as unusual for a design.

View attachment 11703
They use what I believe is a 2" "super dome tweeter" that can handle up to 25watts but it looks alot more like a horn tweeter of sorts. They even implemented an acoustic foam filter that sits in front of it to flatten the response on it. It still really falls off above 18K but Ive never notices any lack in clarity or quality.

Full specs here http://mypicsonline.net/archive/archives.telex.com/archives/EV/Speakers/EDS/Sentry 500 EDS.pdf

My question is how do they keep this speaker so flat for response with only a 2 way design using a 12" woofer and tweeter combination. .
My guess is that is still what we would call a compression driver. It looks like it from the pictures I found online. CD's use a dome diaphragm typically. There are exceptions that use ring radiators or anular rings, but domes are most common. It's possible that it doesn't have the normal opening or doesn't have a phase plug, so I suppose it could be some kind of hybrid to a direct radiator, but the foam plug makes that unlikely.

As for the foam, it is likely to absorb mouth reflections. That waveguide is a typical EV Constant directivity waveguide, which relied on diffraction. It's what Geddes specifically sought to get rid of as he felt it caused problems. One solution, which EV implemented, is to eliminate the reflections in the mouth, and a small foam plug does that. As many know, Geddes took that idea and implemented a GIANT foam plug that files the entire waveguide. It absorbs HOM's, which are soundwaves traveling across the waveguide from the mouth to the end and interfering with each other.
 

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Thanks Matthew, these EVs may not be the best looking speakers but do the job very well. Do you think the deterioration of the acoustic foam on the tweeter would effect the sound? Im not even sure it can be replaced or not.
 

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I bet it can be rebuilt and replaced with modern open cell reticulated foam (filter foam). However, I hate to tell you to touch it. If I'm wrong and touching it messes it up, your stuck.

Are there any support forums where people rebuild them?
 

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I agree touching them is a bad idea till I know for sure it can be done. Ive read a few post on other speaker forums and not alot of info about them. One guy is trying to rebuild the crossovers but unsure if he has had any success with getting the drawings for them.
 

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Great write-up, Matt. I am unsure how to contribute more to the discussion. I will say that I have been using speakers with soft domes for 10 years. They were Phase Technology speakers, a spinoff of United Speaker who used to OEM for a bunch of brands, and the late founder and owner of that company (Bill Hecht) was the inventor and patent holder of the soft dome tweeter. They still make their own soft domes in house. Anyway, I never felt I was missing anything, and in fact I have had time with another model of Phase Technology's that uses a 1" soft dome on the highs and a 3" soft dome on the upper mids (in a four-way design). Its reproduction of piano is some of the best I have heard. Back in the HTS days, in the $3000 speaker comparison, that speaker was part of the evaluation and one of the people present who pays particular attention to the "tinkling" sounds of the piano noted that this particular speaker was his favorite in that regard, IIRC. I'd have to go over that again to be sure.

I have since moved to speakers with aluminum domes (Revel Concerta2 F36 and M16). I hesitate to make a comparison against my former system because literally everything in the system is different, from the source players to the AVR and room correction, amplifier, and even the room itself and its acoustics. But I have not had any complaints about the high end.

Anyway, I think there's a lot to the notion that a tweeter or any other driver is part of a system and a design, and the design has more to do with the outcome than any one particular driver in the design. I have been following Chane for a while, and that is what Jon Lane will tell you about his designs. Not to say the drivers don't have any effect, and I imagine a good designer will consider the goals he has for his system and select drivers that are the best fit for it. I'm no expert, but there are so many facets to the design of a speaker. Consider too that Jon Lane's A series speakers use a planar tweeter, which he touts for its low distortion and large surface area. But he's using a dome in the new L series, which he feels is a better match for the goals he has in mind for that speaker series. It would be fascinating, then, to compare say the A5.4 against the L7 - same speaker designer, same goals in terms of tonal character, but very different driver technologies.

Speaking of comparisons, I have the Revel M16 with aluminum dome and the Chane A1.4 with planar tweeter in house right now. Maybe a comparison between the two is in order once I get my new theater wrapped up. That would be interesting I think.
 

Matthew J Poes

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Great write-up, Matt. I am unsure how to contribute more to the discussion. I will say that I have been using speakers with soft domes for 10 years. They were Phase Technology speakers, a spinoff of United Speaker who used to OEM for a bunch of brands, and the late founder and owner of that company (Bill Hecht) was the inventor and patent holder of the soft dome tweeter. They still make their own soft domes in house. Anyway, I never felt I was missing anything, and in fact I have had time with another model of Phase Technology's that uses a 1" soft dome on the highs and a 3" soft dome on the upper mids (in a four-way design). Its reproduction of piano is some of the best I have heard. Back in the HTS days, in the $3000 speaker comparison, that speaker was part of the evaluation and one of the people present who pays particular attention to the "tinkling" sounds of the piano noted that this particular speaker was his favorite in that regard, IIRC. I'd have to go over that again to be sure.

I have since moved to speakers with aluminum domes (Revel Concerta2 F36 and M16). I hesitate to make a comparison against my former system because literally everything in the system is different, from the source players to the AVR and room correction, amplifier, and even the room itself and its acoustics. But I have not had any complaints about the high end.

Anyway, I think there's a lot to the notion that a tweeter or any other driver is part of a system and a design, and the design has more to do with the outcome than any one particular driver in the design. I have been following Chane for a while, and that is what Jon Lane will tell you about his designs. Not to say the drivers don't have any effect, and I imagine a good designer will consider the goals he has for his system and select drivers that are the best fit for it. I'm no expert, but there are so many facets to the design of a speaker. Consider too that Jon Lane's A series speakers use a planar tweeter, which he touts for its low distortion and large surface area. But he's using a dome in the new L series, which he feels is a better match for the goals he has in mind for that speaker series. It would be fascinating, then, to compare say the A5.4 against the L7 - same speaker designer, same goals in terms of tonal character, but very different driver technologies.

Speaking of comparisons, I have the Revel M16 with aluminum dome and the Chane A1.4 with planar tweeter in house right now. Maybe a comparison between the two is in order once I get my new theater wrapped up. That would be interesting I think.
If you used DIRAC on both, that would help eliminate the tonal balance of the speakers from the equation and leave just the inherent differences in the tweeter.

I didn’t go into it here but there is some debate about CSD’s. Basically that both a direct test of the difference and the underlying issue it highlights have never been verified in sound tests to matter. That is, ABX testing of small amounts of stored energy in drivers has never bared fruit.

I constantly hear speakers that challenge my beliefs about good speaker design. My main speakers have a flat listening window response and a flat early reflection response. However they are a CD design and the early reflection response is quite a bit lower in level than the listening window. What some would call a narrow dispersion speaker. I’m currently testing, in their place, the exact opposite. The speaker also has a flat response at nearly all angles, but it doesn’t change in level either. It’s basically a wide dispersion speaker with a perfect response. I expected it to sound dramatically different. It certainly does but neither sounds more right, and the differences are subtle at best.

My belief is that one of these is the perfect example of the perfect speaker. That the other is a perfect example of a flawed speaker. My ears don’t tell me that’s true. My ears tell me both sound great.
 

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The first reflection response would cover data we don't have here, its 40, 60, 80 in the horizontal, and 50 degrees in the vertical (all plus and minus).

So there is a good argument to be made that if the tweeter looks bad at 30 degree or even 45 degrees, that this might in fact impact the in-room listening window response. If the speakers response falls apart past 30 degrees, then the first reflection response will also fall apart.
Thanks Matthew for some more great info.
 

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If you used DIRAC on both, that would help eliminate the tonal balance of the speakers from the equation and leave just the inherent differences in the tweeter.
Indeed. Perhaps to be fair, it would be good to do a single-point Dirac calibration on each, so the mic position is the exact same for both.

My belief is that one of these is the perfect example of the perfect speaker. That the other is a perfect example of a flawed speaker. My ears don’t tell me that’s true. My ears tell me both sound great.
Isn't that interesting? Measurements matter and are invaluable in the evaluation of audio equipment. But, in the case of speakers in particular, I am of the opinion that we have not figured out how to measure everything that matters. I've heard some people say "if you can hear it, you can measure it." Perhaps, but it's also probable that "you can hear it, but you don't know how to measure it."

We humans are incredibly prone to bias. Science can help us stay objective. But expectation bias can easily go both ways. The speaker costs 5 figures, so it must sound good. Or the speaker measures well, so you expect it to sound good. Or the speaker has a horn-loaded tweeter, so it probably sounds shouty and bright. Very different assumptions based on very different metrics, but all are expectation bias issues. No one is immune. I guess that's why double-blind testing is so important.
 

Matthew J Poes

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Indeed. Perhaps to be fair, it would be good to do a single-point Dirac calibration on each, so the mic position is the exact same for both.



Isn't that interesting? Measurements matter and are invaluable in the evaluation of audio equipment. But, in the case of speakers in particular, I am of the opinion that we have not figured out how to measure everything that matters. I've heard some people say "if you can hear it, you can measure it." Perhaps, but it's also probable that "you can hear it, but you don't know how to measure it."

We humans are incredibly prone to bias. Science can help us stay objective. But expectation bias can easily go both ways. The speaker costs 5 figures, so it must sound good. Or the speaker measures well, so you expect it to sound good. Or the speaker has a horn-loaded tweeter, so it probably sounds shouty and bright. Very different assumptions based on very different metrics, but all are expectation bias issues. No one is immune. I guess that's why double-blind testing is so important.
Well and in this case both speakers measure impeccably. It’s a special case science problem. That is, Toole has said that his research into listener preference found that speakers with a flat listening window and a falling early reflection and power response sound best. Geddes, for theoretical reasons driven by actual preference testing makes an even more extreme arguement. In speaker technical terms, it means an ideal speaker should have an elevated flat directivity index.

So I have two speakers. One has a flat DI elevated at 9dB and with a flat listening window response. I have another speaker with a DI of more like 1dB and with a flat listening window response. Toole and Geddes would contend this is a good speaker but because it’s not more directional it will have an overly strong/loud set of early reflections.

Well, I didn’t hear anything that say well with my presumptions or what that would sound like. The soundstage isn’t better or worse, slight different. In fact, the Geddes speakers tended to make those reverberant effect sounds seem to come from outside the speaker more than the wide dispersion speaker. Opposite of my expectation.

I find this very interesting. I wish I better understood the psychoacoustic effects of early reflections.

I should also say that I have a lot of absorption in this room, it’s possible that with less the two would sound more different. I plan to pull out some panels this weekend and compare again.
 

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What's the best is no doubt subjective. I tend to go back and forth between the flat leaf planar speaker that Jon Lane uses in his A5 speakers... the folded motion in the MartinLogan and Emotiva... and the electrostatic panels in the larger MartinLogan. I haven't found a dome tweeter I like as well as these.
 

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What's the best is no doubt subjective. I tend to go back and forth between the flat leaf planar speaker that Jon Lane uses in his A5 speakers... the folded motion in the MartinLogan and Emotiva... and the electrostatic panels in the larger MartinLogan. I haven't found a dome tweeter I like as well as these.
Assuming you do make it out to AXPONA, I will have to take you to a few of my favorite dome based speakers to see if I can't change your mind. There are a handful, all using Beryllium, that I think you would enjoy.
 

chrapladm

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I am in the same boat as Sonnie for the most part. My next build will be a AMT synergy horn to hopefully end my large speaker builds for a while. Need to go have a listen to some ML's again it has been way too log.
 

ddude003

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I am with Sonnie on this, and completely in the camp of electrostatics when done right... There is just something about their effortless air and sparkle on the top...
 

JStewart

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@Matthew J Poes
Like many I've been waiting for the arrival of the Chane L7 which I'm sure will be a really great speaker, but in going through your article again I'm wondering if that is the best choice because the speakers will be within about 18" of the sidewalls due to width of the room and projection screen.
Do you think a speaker with a CD may be the better choice due to the diminishing volume and similar response when off axis? I also noticed in @tesseract 's review pictures of the JTR 210RT they were not too far from the side walls and he's getting great results with soundstage and imaging.
Thanks!
 

Sonnie

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The problem with listening at Axpona is about 95% setup issues... hardly anything sounds good... literally 5% of what I hear I like. Domes can sound good... just not quiet as good as what I've heard from the alternative. There have probably been 50-60 domes or more thru my room... many of them were very nice speakers... and some I purchased and lived with for a while, but I can tell when I go back to what I really like. Electrostatics are just plain hard to beat when it comes right down to it... but that involves more than just the tweeter range of the speaker.
 

tesseract

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@Matthew J Poes
Like many I've been waiting for the arrival of the Chane L7 which I'm sure will be a really great speaker, but in going through your article again I'm wondering if that is the best choice because the speakers will be within about 18" of the sidewalls due to width of the room and projection screen.
Do you think a speaker with a CD may be the better choice due to the diminishing volume and similar response when off axis? I also noticed in @tesseract 's review pictures of the JTR 210RT they were not too far from the side walls and he's getting great results with soundstage and imaging.
Thanks!
Hello, JStewart.

My room picture is a bit misleading as far as perspective. The speakers are a bit over 18" from side walls, which I consider the minimum distance one would want, so it is a bit tight in the 16x12x8 room. Horns do help greatly, for the reasons you detailed. The Chanes would work fine at that distance, just add 4" absorption traps at the first reflection points.
 

Matthew J Poes

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@Matthew J Poes
Like many I've been waiting for the arrival of the Chane L7 which I'm sure will be a really great speaker, but in going through your article again I'm wondering if that is the best choice because the speakers will be within about 18" of the sidewalls due to width of the room and projection screen.
Do you think a speaker with a CD may be the better choice due to the diminishing volume and similar response when off axis? I also noticed in @tesseract 's review pictures of the JTR 210RT they were not too far from the side walls and he's getting great results with soundstage and imaging.
Thanks!
Well you could always use absorbers on the side-wall.

I have my theories on all this, some supported by the science, but as I noted, some times I hear things that challenge those theories.

What I say about dispersion and sidewalk reflections is true but how it sounds to an individual is a bit of an unknown.

The best answer I can give you is that I think CD speakers are better when being placed near a sidewalk. However they need to provide directivity control down to a pretty low frequency, at least 800hz. Further, I think if a speaker is too close to the sidewalk, a bass trap next to each speaker is still needed because you will get boundary reinforcement from the acoustic mirror effect (note I said next to the speaker and not the first reflection, that’s a different issue).

My opinion is that absorbing first reflections and controlling output through Cd are acoustically equivalent. If the speakers first reflection output is 20dB less than the listening axis and the absorber also only lowers it by 20dB then the reflection is attenuated the same. The problem with the absorber is that they don’t absorb at the incident angle of a first reflection in a linear fashion. Their response is not flat. A good CD speaker is. That’s why I prefer that as an approach.
 

tesseract

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Yes, Matt, if we get too close to the wall, boundary reinforcement starts to favor the lower frequencies and will shift the balance accordingly. This can mess with any baffle step compensation in the crossover, too. Heavy absorption for speakers close to the wall, yes.

I bring up first reflection point for the speakers and distance JStewart mentioned, Chane with wide horizontal dispersion planars, 18" from the sidewall.

I also agree with absorption for these types of wide dispersion speakers at the first reflection point mimics the off-axis response of constant directivity sans absorption. I do not use sidewall absorption for constant directivity, horn or dipole.
 

tesseract

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Chase VS-18.1 x 2 - Subwoofers
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As for tweeter types, I am a fan of, in this order:

1. Plasma has been the cleanest, quickest, clearest HF reproduction I have heard. I can not recall the speaker model (maybe @AudiocRaver can remember, we both heard it), it just sounded effortless.Just that one model, though. I've heard others that did not impress, due to implementation, the room setup, poor dispersion, or other.

2. RAAL ribbons are hard to beat. Their measured horizontal off-axis response is nearly perfect. The vertical nulls quell floor and ceiling reflections. Most natural sounding diaphragm transducer, to me. Limited on the bottom end of their range, like any ribbon, they put a lot of responsibility on the midrange/midbass driver to maintain that natural sound.

3. The annular drivers from BMS are just fantastic, the distortion levels are lower than most any other type I've heard and let everything come through, allowing one to truly hear new sounds in old favorites. The detail is up there with plasma. Get one of there coaxials with a midrange driver and these attributes are pushed down in frequency giving the state-of-the-art performance in the top six octaves, in my opinion.

4.Electrostatic full-range drivers are just sublime from the lower midrange right on up to the top.

5. Planar drivers are not far behind the best and are easy for me to live with.

6. Compression drivers loaded into a horn give the type of dynamics we hear live, amplified or unamplified, small venue. A good waveguide helps negate room issues, too.

7. AMT Heil-type drivers, especially loaded into a horn, give compression driver-like dynamics while often sounding a bit smoother.

8. Domes, they do a good job, but not typically a great one. I have heard exceptions but the prices on these speakers (think Wilson) makes me think about how much money it takes to get domes to sound like the top choices. I think people either uses them out of habit and cost considerations.

9. Full-range drivers give a homogenized sound that I like. I could deal with a set of desktop full-ranges and have heard some uber-floorstanders sound as good as many great multi-way speakers.

10. Cones. Maybe for a garage speaker at background levels. Not gonna please too many ears when cranked, though.

11. Piezo tweeters are strictly a cost consideration that perform pretty poorly, Crank these up and you'll wish you hadn't. Only plus here is that there are extremely durable.
 

JStewart

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My room picture is a bit misleading as far as perspective. The speakers are a bit over 18" from side walls, which I consider the minimum distance one would want, so it is a bit tight in the 16x12x8 room. Horns do help greatly, for the reasons you detailed. The Chanes would work fine at that distance, just add 4" absorption traps at the first reflection points
Well you could always use absorbers on the side-wall.

I have my theories on all this, some supported by the science, but as I noted, some times I hear things that challenge those theories.

What I say about dispersion and sidewalk reflections is true but how it sounds to an individual is a bit of an unknown.

The best answer I can give you is that I think CD speakers are better when being placed near a sidewalk. However they need to provide directivity control down to a pretty low frequency, at least 800hz. Further, I think if a speaker is too close to the sidewalk, a bass trap next to each speaker is still needed because you will get boundary reinforcement from the acoustic mirror effect (note I said next to the speaker and not the first reflection, that’s a different issue).

My opinion is that absorbing first reflections and controlling output through Cd are acoustically equivalent. If the speakers first reflection output is 20dB less than the listening axis and the absorber also only lowers it by 20dB then the reflection is attenuated the same. The problem with the absorber is that they don’t absorb at the incident angle of a first reflection in a linear fashion. Their response is not flat. A good CD speaker is. That’s why I prefer that as an approach.
Thanks guys! Sounds like CD could be better than other tweeter designs with respect to proximity to side walls, but that can be dealt with through absorption too. That puts it in perspective for me. Its a consideration but not deciding factor.
 

tesseract

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Universal / Blu-ray / CD Player
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Center Channel Speaker
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Chase VS-18.1 x 2 - Subwoofers
Video Display Device
Vizio E550VL
Other Equipment
h/k TC35C/Ortofon Super OM10/Pro-Ject Phono Box S
Thanks guys! Sounds like CD could be better than other tweeter designs with respect to proximity to side walls, but that can be dealt with through absorption too. That puts it in perspective for me. Its a consideration but not deciding factor.
The focus here is on tweeters and I do not want to deviate from that topic, but it bears mentioning that blending with the midrange/midbass driver is an important consideration. That is key to the sound of many favorite loudspeakers. Woofers, too...

Another topic worthy of its own thread. :greengrin:
 
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