Why are all tweeters 1 inch in diameter ?

[Alice of Old Vincennes]

What boggles my mind more is how a 1" driver can play so loud. In some configurations it can run alongside a couple of midranges and a few woofers in a large floorstander with upwards of 250W power handling rating. How can annoyingly loud cymbal crashes come cleanly out of a 1 inch thing with <1mm of excursion?

I believe hz will answer your question. Also, the perception of loudness in tweeter frequencies is affected by clean bass and midrange.

 

[mhardy6647]

There is an old trick, beloved of, e.g., Henry Kloss -- the "cone/dome" hybrid tweeter.
These were, in fact, nothing of the sort but rather were cone tweeters with domed dustcaps. The dome would, so ol' Henry claimed, improve high frequency dispersion, while the cone allowed a lower crossover frequency.

It was (I think) a gambit similar in intent to the whizzer cone in an 'extended range' driver, and it may have helped give a broader useable bandwidth to (inexpensive) cone tweeters much beloved (again) by ol' Henry and used in many of his designs (and/or others' designes to which he attached his name or his brand).

Note the bulbous dustcaps on the tweeters on these Cambridge Soundworks (CSW) Model Sixes.

(or on this much older KLH Model 24)

PS many cheap Radio Shack "monkey coffins" of the 1970s and into the 80s used cones extremely similar (at least morphologically) to Kloss's cone/domes (i.e., the tweeters used in the CSW Model Six looked a lot like some of the R/S tweeters of the same era).

Here's a pretty randomly chosen example (not the best possible example, but easy to find!) -- from 1990
https://www.radioshackcatalogs.com/flipbook/1990_radioshack_catalog.html

 

[Alice of Old Vincennes]

Probably the crash itself is lower in frequency and routed/filtered to midwoofer plus midrange so tweeter only handles the splashes but not the crashes ..

Thank goodness for well designed 3 way. I know that 2's and 2.5's are popular. Trying to wrap my head around 2.5. I understand more efficient. But a good amp should not be an obstacle to a 3 way vs 2.5. We all understand the 2 way argument for imaging and maybe soundstage. Yet a 2 way is inherently inefficient. Reminds me of MMG. Cheap but takes a 100 pound a/b amp or a auditorium class D amp to drive. Even Revel is using 2.5 on Concerta. AVR with preouts will solve the mains efficiency issue.

 

[MetalDaze]

PS many cheap Radio Shack "monkey coffins" of the 1970s and into the 80s used cones extremely similar (at least morphologically) to Kloss's cone/domes (i.e., the tweeters used in the CSW Model Six looked a lot like some of the R/S tweeters of the same era).

I owned a pair of Technics SB K45 speakers for a time. Sold them to the record shop across the street from me for $40 to use as part of a window display. They used exactly this type of low tweeter driver. The center cone dust cap was stiff as a rock.

 

[Alice of Old Vincennes]

There is an old trick, beloved of, e.g., Henry Kloss -- the "cone/dome" hybrid tweeter.
These were, in fact, nothing of the sort but rather were cone tweeters with domed dustcaps. The dome would, so ol' Henry claimed, improve high frequency dispersion, while the cone allowed a lower crossover frequency.

It was (I think) a gambit similar in intent to the whizzer cone in an 'extended range' driver, and it may have helped give a broader useable bandwidth to (inexpensive) cone tweeters much beloved (again) by ol' Henry and used in many of his designs (and/or others' designes to which he attached his name or his brand).

View attachment 106580
Note the bulbous dustcaps on the tweeters on these Cambridge Soundworks (CSW) Model Sixes.

View attachment 106581
(or on this much older KLH Model 24)

PS many cheap Radio Shack "monkey coffins" of the 1970s and into the 80s used cones extremely similar (at least morphologically) to Kloss's cone/domes (i.e., the tweeters used in the CSW Model Six looked a lot like some of the R/S tweeters of the same era).

View attachment 106582
Here's a pretty randomly chosen example (not the best possible example, but easy to find!) -- from 1990
https://www.radioshackcatalogs.com/flipbook/1990_radioshack_catalog.html

I think they were really, really trying to figure it out back then. Smart guys without the technology. Amir purchased testing equipment not available at any price back then. Let's grant our Canadian friends credit. The Immaculate Conception that created Toole.

 

[Alice of Old Vincennes]

I owned a pair of Technics SB K45 speakers for a time. Sold them to the record shop across the street from me for $40 to use as part of a window display. They used exactly this type of low tweeter driver. The center cone dust cap was stiff as a rock.

Like to see those babies tested. Looks like an inverted lens. They were on to something.

 

[CTS]

While on the topic of beaming.. is also interesting to note that different diaphragm geometries affect how gradual the beaming effect sets in, say the Bliesma T34A vs T34B (exact same motor and soft parts, just a different dome material & geometry), and ring radiator designs such as the ubiquitous Peerless XT25 has significantly narrowed dispersion as the center of the dome (higher frequencies generate closer to center) is 'plugged'.

A good example of importance of diaphragm geometry can be seen here where the slightly concave Accuton C30 (with 8.55cm2 surface area)
Measurements from hificompass.com

versus the convex Bliesma T34A with 10.5cm2 surface area

Both are operating in pure piston mode to 20khz.

Dispersion isn't strictly tied to radiating area and beaming is something I feel is more relevant to crossover optimization.
Other interesting points of consideration (excluding waveguides) are for instance metal tweeters with phase shields like the SB26ADC and ScanSpeak 9800. And something like the phasing grille PMC uses on their pro models MB, BB, QB and IB2S, although in this case the tweeter is a soft dome Audax TW034.

Also on the topic of low end extension, there are 2 criteria 1 is low nonlinear distortion which is often credit to a well tuned rear chamber more so than a driver size. Take the SB26ADC for example, it is a 'small' 26mm with better low end than many 34mm tweeters. 2nd criteria is thermal and mechanical and in this case larger tweeters often have single layer coils vs multi layer found in smaller tweeters.. so the end result is similar. Mechanical excursion from lower frequencies can also break the voice coil lead wires regardless of size.

IMO the 104mm flange/1 inch tweeter is more of a industrial habit to stick to what is tried and proven to work, and easier to sell to manufacturers. When selecting a tweeter I tend to consider other priorities first, dispersion characteristics has much more nuances than calculated beaming freq, and less of a hard & fast distinction vs say woofers/mids. And we aren't even talking about waveguides which is a whole nother topic altogether
Anyways just sharing one side of the perspective.

 

[phoenixsong]

I find that many manufacturers fervently hype their speaker tweeters, be it the waveguide or the tweeter construction itself, but not the woofers. Is it because of the tweeter's relative sensitivity as demonstrated above?

 

[q3cpma]

But it generally needs a higher crossover frequency Iike 3-5 kHz, so you can’t use it in a 2-way speaker. You really need 3-way speakers if you want a tweeter smaller than 1” / 25mm. That’s the real reason why 1” / 25mm tweeters are the default size.

Genelec uses them in their 8x20, 8x30 and 8x40 with no problem except a tiny bit of distorsion from the woofer at 3 kHz.

 

[Frank Dernie]

There is an old trick, beloved of, e.g., Henry Kloss -- the "cone/dome" hybrid tweeter.
These were, in fact, nothing of the sort but rather were cone tweeters with domed dustcaps. The dome would, so ol' Henry claimed, improve high frequency dispersion, while the cone allowed a lower crossover frequency.

It was (I think) a gambit similar in intent to the whizzer cone in an 'extended range' driver, and it may have helped give a broader useable bandwidth to (inexpensive) cone tweeters much beloved (again) by ol' Henry and used in many of his designs (and/or others' designes to which he attached his name or his brand).

View attachment 106580
Note the bulbous dustcaps on the tweeters on these Cambridge Soundworks (CSW) Model Sixes.

View attachment 106581
(or on this much older KLH Model 24)

PS many cheap Radio Shack "monkey coffins" of the 1970s and into the 80s used cones extremely similar (at least morphologically) to Kloss's cone/domes (i.e., the tweeters used in the CSW Model Six looked a lot like some of the R/S tweeters of the same era).

View attachment 106582
Here's a pretty randomly chosen example (not the best possible example, but easy to find!) -- from 1990
https://www.radioshackcatalogs.com/flipbook/1990_radioshack_catalog.html

People naturally apply "static" thinking to uses which are truly dynamic. It isn't just non-scientists either, the head of the research department when I was doing noise and vibration research said he couldn't visualise what happened at resonance and above, so preferred not to think about it , luckily, he did accept the maths so we didn't get the sort of bollox we see in discussions about, mainly, record players, but I have found it common.
We talk about pistons of 1" having such and such characteristics, but in fact almost none of the tweeters fitted to commercial speakers are made in designs which could remain a piston for their whole pass band. This is mainly because of available materials and the ease (ie cost) of making complex shapes.
The reality of dispersion at highest frequency will depend on the break up modes of the tweeter at least as much as its diameter.

Imagine what is going on dynamically with these cone tweeters!
It doesn't matter how "good" the dust cap is at higher frequencies when it has a relatively huge area of flapping cone driven by the same voice coil all around it.
Once the diaphragm has gone modal, ie is above its first breakupo mode, dispersion will depend on the dynamics not the dimension.
The idea for NXT, and its offspring BMR, came from the study of breakup.
As long as the excitation is decoupled cleverly and non-symetrical a panel can be excited at a lot of its modes and their harmonics at once, rather than a few symmetrical ones. This results in far more but much lower individual peaks and wide radiation.
Traditional drivers have far fewer much bigger peaks, which need either effective damping or moving out of the driver's operating range. This latter has only been feasible in recent years due to crossover and material reasons.

 

[Mnyb]

Burchart uses 19mm tweeters in a two way but the wave guide is huge , so does this fix the impedance match so the lower xo is feasible? The wave guides primary objective is to match directivity with the woofer , but burchart seems to use this other property too ?

 

[testp]

and here i thought tweeters are for tweeting...

 

[andreasmaaan]

Burchart uses 19mm tweeters in a two way but the wave guide is huge , so does this fix the impedance match so the lower xo is feasible? The wave guides primary objective is to match directivity with the woofer , but burchart seems to use this other property too ?

The distinction between a "waveguide" (as it's often used in audio) and a "horn" is rather nebulous IMO.

All "horns" necessarily affect radiation pattern, and all "waveguides" necessarily affect acoustic impedance.

To stretch this just a touch further, the same is also true of all enclosures (especially baffles) - these affect both radiation pattern and acoustic impedance according to the same principles as horns/waveguides.

 

[andreasmaaan]

I find that many manufacturers fervently hype their speaker tweeters, be it the waveguide or the tweeter construction itself, but not the woofers. Is it because of the tweeter's relative sensitivity as demonstrated above?

The cynic in me says it is because exotic materials can be much more cheaply utilised in small surface-area diaphragms.

My more generous inner voice says it is because the tweeter generally covers the frequency band (2-5kHz-ish) in which our ears are most sensitive.

 

[Thomas savage]

Of course, but how detailed did you want? This was sea level, dry air, standard temp and pressure. Humidity is also a first-order effect. Feel free to provide the whole equation; I was too lazy to look it up in my old acoustics text so just spouted off what I remembered off-the-cuff. And of course you don't go from wide dispersion to beaming immediately, there's a transition period. And so forth. I just wanted to put some ballpark numbers out there for people to calculate on their own. The only one I remember is 1127'/s; the rest of the digits are from the calculator.

Ha ha theres always one isn't there don .

 

[thewas]

The cynic in me says it is because exotic materials can be much more cheaply utilised in small surface-area diaphragms.

The cynic in me says that it's also easier to manufacture a planar tweeter or AMT on your own in a small manufactory as a unique selling point than a cone driver.

 

[PuX]

Dynaudio used to make speakers with a second, larger tweeter.

not sure if it was meant to cover a part of higher frequencies or mids.

 

[andreasmaaan]

Dynaudio used to make speakers with a second, larger tweeter.

not sure if it was meant to cover a part of higher frequencies or mids.

This is what's called a dome midrange. These work on the same principles as a dome tweeter, but are larger, being designed to cover upper midrange frequencies. Typically, they cross over from the woofer somewhere in the 400Hz-1000Hz range, and cross over to the tweeter somewhere in the 3kHz-5kHz range.

 

[mhardy6647]

People naturally apply "static" thinking to uses which are truly dynamic...
Imagine what is going on dynamically with these cone tweeters!
It doesn't matter how "good" the dust cap is at higher frequencies when it has a relatively huge area of flapping cone driven by the same voice coil all around it.

I wasn't defending, merely reporting.
Note that we don't see many cone tweeters any more (even though there were some perfectly OK sounding ones -- the old Peerless AlNiCo cone tweeters perhaps the best of the lot, and widely used they were).

Once the diaphragm has gone modal, ie is above its first breakup mode, dispersion will depend on the dynamics not the dimension.
The idea for NXT, and its offspring BMR, came from the study of breakup.
As long as the excitation is decoupled cleverly and non-symetrical a panel can be excited at a lot of its modes at once, rather than a few symmetrical ones. This results in far more but much lower individual peaks and wide radiation.

Heh. NXT. I have this weird little NXT portable speaker/amp thing (a long-ago dump find) that we use upstairs in the bedroom for "Holiday Music" with a little digitial audio player during the... well... holiday season.


I always assumed the "poly-planar" drivers of the 1960s were based on the same concept(?).

source: https://worldradiohistory.com/Archive-Catalogs/Lafayette-Catalogs/Lafayette-1969-690.pdf

 

[mhardy6647]

This is what's called a dome midrange. These work on the same principles as a dome tweeter, but are larger, being designed to cover upper midrange frequencies. Typically, they cross over from the woofer somewhere in the 400Hz-1000Hz range, and cross over to the tweeter somewhere in the 3kHz-5kHz range.

They were a thing in the 1970s.

P1020547 by Mark Hardy, on Flickr
ads L710 (e.g.)

Philips had a nice one -- sold for DIY use and also found in numerous, mostly European, loudspeakers (e.g., Philips, b&o) BITD.

AH477etc by Mark Hardy, on Flickr
Philips AH-477 (e.g.)

R/S, not atypically, was a bit of a late adopter.

https://www.radioshackcatalogs.com/flipbook/1980_radioshack_catalog.html

They're still around, although dimimished in popularity.

https://www.parts-express.com/search?keywords=dome midrange (a couple of misfires in this list, but it'll give a sense of what PE carries)
e.g.,
https://www.parts-express.com/HiVi-DMN-A-Soft-Dome-Fabric-Midrange-297-415?quantity=1