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Revel F228Be Review (Speaker)

restorer-john

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@amirm Your 228 measurements show a significant difference in the high end rolloff (both on an off axis) as compared to the 208 and the 328. These 228s start to plummet above 12kHz.
 

amper42

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Would a Purifi 1ET400A amplifier with 425 W @4 Ohms and 227 W @8 Ohms be sufficient to drive these speakers at sufficient volume without degrading the low end?

So far the Purifi 1ET400A is my favorite with the Revel F328Be. I setup the Monolith 7X200 and the March Audio P452 so I could easily switch between the two amps with matched levels. The Purifi amp sounded a bit smoother to my ears with the Revel F328Be. Absolutely no lack of bass power. It's a great match in my setup. I can't imagine the Purifi wouldn't do an amazing job with the Revel F228Be as well.

At some point in the future I would like to complete the same test with the BenchMark AHB2.
 
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amirm

amirm

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Is that a Revel Performa M20 up on the wall unit next your TV?
I think so. Lost track of what model number it is as I have had it for a long time. As to measuring it, it is the main speakers for the TV. Pulling one out will shift the sound to one side so may be hard to do. :)
 
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amirm

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@amirm - Did you use the "Bass Numerical Optimization" method that you later added to The Revel F328Be Review for the F228Be review? Thank you!
Yes, all new tower speaker measurements use this optimization. It is kind of time consuming as I often have to run the analysis stage multiple times but it is necessary. I have even tried it on smaller speakers but it makes no difference there which is good.

And as I noted, I have retroactively fixed the F208 and will fix more as I have time.
 
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amirm

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@amirm Your 228 measurements show a significant difference in the high end rolloff (both on an off axis) as compared to the 208 and the 328. These 228s start to plummet above 12kHz.
I realize that but not sure how to explain it as it also shows up in straight, static, non-NFS measurements used in distortion graphs:

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I will check the microphone and makes sure nothing has come loose on it but other than that, it is hard to know what is going on. I measured a Genelec before this and it agreed with company's own measurements (they measure each sample before shipping).
 
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amirm

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Would a Purifi 1ET400A amplifier with 425 W @4 Ohms and 227 W @8 Ohms be sufficient to drive these speakers at sufficient volume without degrading the low end?
Yes, all my listening tests were with the Purifi amplifier (reference design). I did not need to go above -10 dB or so on my DAC even though I was just playing a single speaker in a very large space. These are very efficient speakers as Revels go.
 

phoenixdogfan

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Would be interesting to further explore the differences between the "F" series and the "F---be" series. It does not appear to me the F228 be, though much better looking cosmetically, distinguishes itself from the F208 on flatness of the FR curve, smoothness or width of the polar plots, or bass extension. For me that leaves the question of which design can player louder with lower levels of distortion. I don't think there is a definitive answer to that question, and it would be an integral key to evaluating their respective values.

It also occurs to me looking at any number of these reviews that a many of these modern speakers are well engineered and can be eq'd to a relatively flat LW provided their directivity response is smooth, so it seems again that the things that will differentiate one design from another are cosmetics, power handling, active vs passive, form factor, and price.

Good news indeed because it indicates many high end manufacturers are getting the Harman religion. and consumers can now have their choice of some very capable designs across a wide variety of models and prices.
 
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amirm

amirm

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Good news indeed because it indicates many high end manufacturers are getting the Harman religion. and consumers can now have their choice of some very capable designs across a wide variety of models and prices.
Indeed. The problem is that none publish measurements and without it, we don't know if they are or are not following the same methodology.
 

richard12511

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You are right,I was using the old measurements. These ones do look quite "ripply" too.

Why do you think that is, has anything changed in the measuring setup that would justify this?
Also, have you made these second measurements available for download?

He increased the resolution, which is what adds those extra "ripples" and decreases the score. In the F208s case, the score actually increased, but only because the new measurements show much greater bass extension(due to a different fix).
 

richard12511

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I realize that but not sure how to explain it as it also shows up in straight, static, non-NFS measurements used in distortion graphs:

index.php


I will check the microphone and makes sure nothing has come loose on it but other than that, it is hard to know what is going on. I measured a Genelec before this and it agreed with company's own measurements (they measure each sample before shipping).

I know that all three actually use different waveguides, as the F328 isn't just a bigger F228, but rather a new design with a better waveguide.
I think they may also all have different tweeters, but not sure between the F328 and F228.
 

phoenixdogfan

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Indeed. The problem is that none publish measurements and without it, we don't know if they are or are not following the same methodology.
And in no small measure what you, Audioholics, Archimago, Napilopez, and Erin's Audio Corner have really put their feet to the fire, so let's hope more reviewers start doing 2034 Spins. You got your ears on, JA?
 

Asinus

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I know that all three actually use different waveguides, as the F328 isn't just a bigger F228, but rather a new design with a better waveguide.
I think they may also all have different tweeters, but not sure between the F328 and F228.
According to an AH(?) interview of Jim G (the Revel marketing guy) and photos/video within only the midrange is the same, the woofers and tweeters diaphragm are the same size but the motors are bigger on the 328.
 

richard12511

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According to an AH(?) interview of Jim G (the Revel marketing guy) and photos/video within only the midrange is the same, the woofers and tweeters diaphragm are the same size but the motors are bigger on the 328.

That's what I was thinking, but couldn't remember 100%. Different tweeter and different waveguide could certainly cause those measured differences.
 

MZKM

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You got your ears on, JA?
He currently measures +/-90° horizontal and +/-45° vertical.

In a recently speaker he only did +/-45° horizontal and said the room didn’t allow him to do the normal +/-90° due to the shape of the room. I didn’t understand that (it’s on a dolly, just rotate it more), he responded to me but I still didn’t get it (would on-axis reflections be too strong?).

My main concern is when JA decides to fully retire, who will continue to do measurements.

______
I won’t go too into detail, but BestBuy was fully on board to do Spins and advertise the Olive scores of speakers they sell.

I think Crutchfield is trying to do something as well; they have that anechoic chamber they use to do virtual speaker comparisons.
 
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amper42

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The Revel F328Be definitely offers a hefty Tweeter. The sound quality of the tweeter doesn't have the shimmer my RAAL tweeters (Sierra Towers) offer with cymbals. Instead, it's a more detailed sound. At first, I missed the shimmer of the RAAL but I started realizing in was a bit less defined than the F328Be tweeter.

In my room once Audyssey Reference EQ was applied (With NO DEQ) it flattened out the room curve in the 40-65Hz area with a -5dB cut and elevated the 1800 to 20,000Hz area by approx. +3dB. That small change really opened up the sound. Moving between Direct and Reference mode allows the user to hear the difference with a single button. The F328Be Tweeter offers a lot of output.
 

Francis Vaughan

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For the bass alignment the absolute numbers matter, as in principle these are set by the underlying physics.

Harman's spin for the F226Be shows the break point for the bass rolloff at about 70 Hz. They list bass rolloff as 33Hz (–10dB); 36Hz (–6dB); 48Hz (–3dB), and their spin suggests these numbers about right, although I would have put the -3dB point at more like 55Hz.
Their quoted and measured sensitivity is 90dB 2.83V/1m, which is the same as the F228Be. The F228Be should have roughly twice the swept volume as the F226Be. So given they have the same sensitivity, one would expect lower frequencies for the breakpoints in the F228Be bass response.

Harman's quoted spec for the F228Be are 30 Hz (-10dB); 33 Hz (-6dB); 44 Hz (-3dB). All of which are roughly 3Hz lower than the F226Be.
But the Klippel numbers show a breakpoint of about 85Hz, -3dB at about 65Hz, -6dB at about 45Hz, and -10db at about 25Hz.
Probably the critical number is the 3dB point, as this is usually used as the figure of merit for a bass alignment. Harman's number is 44Hz, the Klippel number is about 65Hz. That is a significant mis-match, and significantly worse than the Harman measurements on the smaller but otherwise very similar F226Be, especially as both loudspeakers have the same nominal sensitivity, and apparently share the same mid-range and tweeter.

Klippel measures the -10db point as significantly better than Harman, 25Hz versus 30Hz. So there is something odd here as well. At this low a frequency it is probably stretching the Klippel system no matter what. Wavelengths are over 10 metres and the ability of the system to differentiate room modes from the near-field measurements will be suffering.

The reason I am puzzled is that of all the aspects of a speaker's response, the bass response is the bit that is the hardest to get any response other than what the very simple physics of the matter determines. The location of the roll-off and its shape are not subject to any magic, they will fall where the simple mechanical properties of the system dictate. And here, the numbers are not falling where one would expect them to.
 
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napilopez

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If you actually overlay the on-axis response on the same graph as F228Be, it actually shows less bass extension! That is of course not true. The dashed red line shows that the total sound power is higher than what on-axis shows. The rear port is a bit directional producing more output going out the back than forward. I checked @MZKM and fortunately he tells me that the preference score uses the sound power there for low frequency extension. But visually we need to be mindful of this differential when looking at rear ported speakers like F328Be.

The F228Be fortunately has a front port so that is not an issue as evidenced by the on-axis and sound power both being the same in low frequencies.

Yeah, to emphasize the point, the preference paper specifically says sound power is used because of rear ported speakers.

"The sound power curve (SP) is used for the correlation when it is applied to the on-axis and calculation because it better defines the true bass output of the loudspeaker, particularly speakers that have rear-firing ports."
 

astrex342

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The 708P seems to go lower in response (vertical directivity is not as good though). I am confused how a much larger speaker with more 8" drivers rolls off much higher. Can someone shed some light on this?

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It's because they expect them to be used in different conditions, and have tuned bass differently
708p is tuned to have maximal flat response, but it rolls off steeper after that flat response.
JBL 708P Measurements Predicted In-room frequency response spinorama cea-2034.png

Revels have a very low port tuning, so their bass decreases a bit earlier, but the steep rolloff does not begin until about 30hz so has more bass energy at sub-bass areas.
Revel F228Be Predicted In-room Frequency Response Measurements Speaker floor standing.png

This is probably because revels are expected to be used in untreated rooms and use room gain to make up for the deficiency in ~60hz bass. KEF's are also tuned this way.
 
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