I have not yet purchased the FR5 speakers. While I have not purchased many speakers in my lifetime, I generally prefer speakers with high crossover point. Could you please provide me with the pros and cons of having low versus high crossover points? I have noticed that the FR5 speakers have a low crossover point of 1.7. This information has raised some concerns for me. Would this speaker benefit from a refresh, such as a MRKII? I have observed that many speaker brands refresh their speakers over time.
The flat panel ribbons sound fantastic.
The FR5s were the last to be developed in the Aspen series following the 30ās 20ās and 10ās. I have the FR10ās and they are outstanding. I doubt there is any need to release a MKII as it seems Chris B. got it right the first time. Consider the in-home trial. Youāll be hooked.
Please correct me if Iām wrong, but arenāt you best off with the crossover as low as the tweeter can play? Just from a physics standpoint, the smaller driver has less mass and should be able to react faster, which has advantageous for SQ. Speaker designers try to use it as long as possible but not all tweeters can play as low. Smaller driver will have limited output and struggle to product bass at volume, so a woofer is added for the area the tweeter canāt fulfill. The two drivers need to pair together, but I think you want your fastest driving playing as much as it can. Big woofers can move a lot of air and can product longer/deeper waves easier; however, big woofers in general struggle to play up high and you would not want your woofer trying to do the cymbals. They are just too big to change direction quickly enough. I donāt know of any advantages of having a higher crossover and think it may be other aspects of those speakers you preferred.
If you look at this speaker design from Tekton, I think the entire idea of the design was to use a group of tweeters to give the output of a mid bass woofer with the advantages of speed through that range. From my understanding, one of those tweeters is operating as the speakerās tweeter and six are running together as the mid woofer. I of course should note I have never heard these speakers and donāt know that this works, but I think that is the concept and they patented the design and spacing so others could not copy.
I would have thought the lower crossover point of the FR5 to be an indication of an advantage.
Some background on your question, as much of this answer relates to speaker directivity.
When looking at the speaker radius (a) versus the frequency itās playing (lambda or Ī»), we use a dimensionless ratio called wavenumer (k) times the radius of the piston of the driver. Defining ka = Ļd/Ī» (k = wavenumber, a = radius):
A driver with ka < 1 is omnidirectional, ka ā 1 is transitional to being direction and ka >1 starts to beam.
A typical 6.5" woofer (say for a diameter including half of the surround, which is part of the active radiating area) is about 6.5 cm in radius and Iāll use that to where that cone size is ka = 2 - a directivity index of 2.5 or about 110 degree coverage at -6 dB - a good place for a home audio speaker.
Solve ka = 2 for frequency:
f = c / Ļa = 343 / Ļ * 0.065 = 343 / 0.2042
f = ~1680 Hz
So right around 1.7 kHz the driver is starting to narrow audibly and this would be a good place to cross over to a tweeter. If you push this frequency up to 2.5 kHz, the DI is around 4 (or an 80 degree coverage.
A 1 inch dome, not including baffle effects has a ka = 0.39 so is essentially omnidirectional. The baffle adds 3 dB of directivity to both but the tweeter is still much less directional than the 6.5" midwoofer.
This is why you see an off-axis dip then flare in the repones of a lot of 2 way speakers. The midwoofer starts becoming directional before handing off to the tweeter.
Here is an example of the harbeth M30.2 as measured by stereophile.
The speaker has a very flat on-axis response but you can see the behavior I described where the off-axis behavior has a dip at the top of the wooferās passband and flare at the bottom of the tweeterās pass band.
Here is an example of the the FR5. Note that you can still see a small narrowing in the woofer vs tweeter directivity at the crossover but the effect is much less pronounced. We will eventually do more work with shallow acoustic waveguides / horn lenses to further improve this in future models but it is already better than many 2-way speakers on the market.
People like Floyd Toole did a lifetime of research about listener preference of speaker response and, while having a flat, smooth on-axis response is very important, so is having a smoothly tapering off-axis response. Meaning, the early reflections (off-axis sound bounding off the walls an ceiling) should mirror the on-axis curve in shape, just lower and level and without resonances or directivity discontinuities.
Speakers with a higher crossover point have worse off axis response unless the tweeter is quite directional to match it. Wider directivity is generally better for typical rooms though. Wide, uniform dispersion produces lateral reflections that are spectrally similar to the direct sound, which listeners consistently prefer (it enhances spaciousness without coloration).
There are a number of other consequences to midrange to tweeter crossovers that put practical limits on where a designer may cross things over. Cone modes/resonances limit the usable upper frequency limits of a midwoofer and distortion, compression and reliability can limit the low frequency limits of a tweeter.
The long and short of it is that we happen to have a tweeter design that works rather well at low crossover points from a distortion perspective and are taking advantage of that to give you a better sounding speaker versus using a higher crossover point.
Lord have mercy. Nobody told me Chris was going to be following my post with formulas, graphs, and logic. If I knew that was coming, I should have simply gone with, āLadies and gentleman, may I introduce to you one of the speakers designers and an actual expert on the matter, Chris Brunhaver!ā
Chris, thanks for the grace in leaving off āThey are wrong, please ignore the aboveā from the start of your post while also doing an excellent job of explaining things I was ignorant of. Iāll try to stop guessing at your designs in the future.
Haha, well, Iām glad you found it interesting.
I didnāt mean to just jump into to much math but I was just trying to illustrate part of the reasons behind crossover points and speaker tonality and sound quality.
Wish of would have heard them in Las Vegas store but they were close when I was there. Iām looking at hifi stores in Los Angeles and no one has them. I might wait till the next time I visit Las Vegas or expona 2027
My copy of āA Brief History of Timeā is unfortunately long gone so I had to resort to AI for this Stephen Hawking quote from the original edition: āSomeone told me that each equation I included in the book would halve the sales. I therefore resolved not to have any equations at all. In the end, however, I did put in one equation, Einsteinās famous equation, E=mc^2. I hope that this will not scare off half of my potential readers.ā
I suspect your readers are as unperturbed as Hawkingās proved to be.
Thereās a FR 5 MKII already?
Not yet but the OP is correct that weāll eventually refresh the product line and have been researching improvements that could be incorporated into new products. Really, every good brand is doing this continuously