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Revel F208 Tower Speaker Review

BYRTT

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I think you are on the right track with respect to cancellation due to the port as that would explain the dip I am seeing. On the rest, that is not how the system works. Klippel NFS has no visibility into the design of the speaker. It simply measures the response around the speaker and uses that to construct an equation that predicts the response. What a speaker is, is as a black box to NFS.

Now, there may be an inherent issue with the measurement but it is not due to this factor.

Thanks look it up a pity its not so easy to solve or could solve itself :)

Probably sounds stupid but feel its like NFS analyze has clearly seen that port output is inverted and marked as so and probobly has full IIR track of phase data, but then under compute process say for range below where gating kick in then software remove IIR track of phase because calculation will benefit in speed caculate only on amplitude curve and then it goes wrong for the part below gating range because some part of it is still marked as inverted and in phaseless FIR land summing inverted to non inverted seems makes cancelation interference, same as don't invert one of two summing 2nd order slopes if they of FIR where IIR land will work perfect optimal with one inverted.
 
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Alice of Old Vincennes

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Thanks look it up a pity its not so easy to solve or could solve itself :)

Probably sounds stupid but feel its like NFS analyze has clearly seen that port output is inverted and marked as so and probobly has full IIR track of phase data, but then under compute process say for range below where gating kick in then software remove IIR track of phase because calculation will benefit in speed caculate only on amplitude curve and then it goes wrong for the part below gating range because some part of it is still marked as inverted and in phaseless FIR land summing inverted to non inverted seems makes cancelation interference, same as don't invert one of two summing 2nd order slopes if they of FIR where IIR land will work perfect with one inverted.
Sounds more complicated than day tradings put and call options on Ameritrade.
 

GXAlan

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Surprising that a Revel flagship of that era would have a ceramic magnet woofer. The step down Performa series had beautiful drivers. While the systems engineering in the newer Performa lines is likely more advanced, I doubt the cone drivers (either Performa3 or PerformaBe) are equal to the previous ones. The old Performa drivers look like they use adapted JBL Pro monitor motors. Note these speakers were designed before the huge neodymium spike last decade.

Jerry Moro did design those drivers: C32R-4, C32R-5, F32R-5, F32R-6, M22R-6 (Performa Series)

He is responsible for the woofer in the JBL M2, along with the Everest line. He also designed all of the drivers in my JBL 4319.
 

Juhazi

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Thanks look it up a pity its not so easy to solve or could solve itself :)

Probably sounds stupid but feel its like NFS analyze has clearly seen that port output is inverted and marked as so and probobly has full IIR track of phase data, but then under compute process say for range below where gating kick in then software remove IIR track of phase because calculation will benefit in speed caculate only on amplitude curve and then it goes wrong for the part below gating range because some part of it is still marked as inverted and in phaseless FIR land summing inverted to non inverted seems makes cancelation interference, same as don't invert one of two summing 2nd order slopes if they of FIR where IIR land will work perfect with one inverted.

Using phase info and playing with it in simulations is something I'm not capable of doing. but I have vivid imagination so I've been just guessing where the poor bass response of towers in Amir's NFS comes from. My exlanation is that because Amir doesn't use Multiplexer add-on, nearfield scan catches just main bass drivers' output and is not able to sum those together and with port signals, like farfield measurements and reality do.

Quasi-anechoid method is problematic as well, it may skip baffle loss and phase mismatch. Model of that concentrates on what happens at resonance frequency, but is deficient above that because slopes/phase are not beautifully symmetric any more IRL.
 
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amirm

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My exlanation is that because Amir doesn't use Multiplexer add-on, nearfield scan catches just main bass drivers' output and is not able to sum those together and with port signals, like farfield measurements and reality do.
That is not what the module is for. The multiplexer is used when the soundfield becomes extremely complex due to many drivers playing at once, creating a very complex soundfield. Examples are professional arrays and soundbars with many drivers.

In low frequencies complexity is not high because the soundwaves for the most part are spherical/low order.

Note that I have provided my measurements to Klippel team including the chief researcher/architect of the system and they see no issues in it. And certainly have made no suggestion of using that module.
 

Alice of Old Vincennes

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Ohh come on. Revel did not start out with wave guides. JBL thought about it years before. Incremental improvements . Multiple 8 inch drivers move more air. Seconding guessing Toole, Rich and Harmon with "this" is a hobby.
 

richard12511

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amirm, seems official spins have been posted by Kevin Voecks in the avs forum: https://www.avsforum.com/forum/89-speakers/710918-revel-owners-thread-408.html#post56177990

Also the explanation is interesting:

Hello All,
There is visual confusion when trying to evaluate the listening window curve that lies on top of the much less valuable on-axis curve. Therefore, I have attached the F228Be Listening Window curve by itself, which is extremely good. I have also attached the Performa F208 Listening Window along with the Performa F228Be listening window, allowing a much easier visual comparison. As our research has long indicated, the listening window is a far better indicator of direct sound quality than is any on-axis curve. On-axis curves measured from just slightly different microphone locations will yield different results at high frequencies due to trivial local diffraction, making them misleading. The listening window greatly mitigates this problem.


Please note that these curves are not just a new format, but have been made with an entirely new measurement system, using the Klippel Analyzer, along with an updated anechoic chamber LF calibration. Therefore, these updated measurements, done with the same system, allow for valid comparisons. It is clear from these curves that the LF amplitude response is the same for both the F208 and F228Be. (Thank you to Mark Glazer for late Friday night work on these!)

View attachment 63191

Interesting, the be model looks even flatter. Given that the 208 is our best measured passive yet, I'm wondering if the Be model can beat the Genelec active.
 

richard12511

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In preference rating list not out of box stand alone :) it needs sub support to beat R3.
Probably in shipping cost it can beat it ...:p

I honestly don't see how the R3 can beat it without a sub. Could this just be the R3 going for max extension at the expense of max output? If so, I'd prefer the Revel.
 

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@Erik_N that's a lovely retreat. Huge screen...
Thank you @Ron Texas ! Before this screen I had a 1,78:1 (92") with the same height, then widescreen movies felt small. This screen feels prefect in my room and fills up the space between the speakers, but you have to sit in the two center positions to not have a speaker in from of the screen. :)
 

QMuse

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In preference rating list not out of box stand alone :) it needs sub support to beat R3.

Although I haven't measured in-room response of R3 during that test (I was hoping for R7) I have listened F208 and R3 side by side and bass coming from F208 was MUCH more convincing and deeper. Room was app 25m2 and R3 was struggling to fill it with sound while F208 did that effortlessly and with authority. Comparing NFS charts IMHO doesn't give you a good idea what kind of bass response speaker is really able to provide.
 

BYRTT

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...nearfield scan catches just main bass drivers' output and is not able to sum those together and with port signals, like farfield measurements and reality do...

If it just catches main bass drivers it should look closer to the left model below that toggle between 2x SB23NBACS45-8 into 60 liter Q(tc)0,8113 ported @30 verse plugging the port alas a sealed Q(tc)0,8113, the funny thing is the right model is same as the left model using inverted port output and non inverted woofers, but left model use minimum phase curves as base in simulation and right model use linear phase curves as base and happens land as relative close to ASR analyze as the left model in ported mode happens land relative close to Revel year 2007 spinorama data.

3.gif
 

BYRTT

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I honestly don't see how the R3 can beat it without a sub. Could this just be the R3 going for max extension at the expense of max output? If so, I'd prefer the Revel.
Although I haven't measured in-room response of R3 during that test (I was hoping for R7) I have listened F208 and R3 side by side and bass coming from F208 was MUCH more convincing and deeper. Room was app 25m2 and R3 was struggling to fill it with sound while F208 did that effortlessly and with authority. Comparing NFS charts IMHO doesn't give you a good idea what kind of bass response speaker is really able to provide.

Boy in me probably agree F208 looks more like a real speaker and also i used smileys in that post, but numbers are numbers so within a reasonable SPL throttle for R3 it should beat R208 stand alone as analyze say so far but if we take the difference in previous post from left ported one to right ported one and add to ASR spinorama it will improve a ton in bass to same as Qmuse curve from dealers shop and then it will probably take over R3 in stand alone numbers as seen in below animation :)
richard12511_1000mS.gif
 

thewas

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Although I haven't measured in-room response of R3 during that test (I was hoping for R7) I have listened F208 and R3 side by side and bass coming from F208 was MUCH more convincing and deeper. Room was app 25m2 and R3 was struggling to fill it with sound while F208 did that effortlessly and with authority. Comparing NFS charts IMHO doesn't give you a good idea what kind of bass response speaker is really able to provide.
Especially if you compare standmounts and floorstanders, as due to the different position (and often number) of woofers you can often get better position dependent bass dips filling with standmount loudspeakers.
 

QMuse

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Especially if you compare standmounts and floorstanders, as due to the different position (and often number) of woofers you can often get better position dependent bass dips filling with standmount loudspeakers.

I should also add that during listening comparison test R3 was mounted on a stand sitting side by side with F208 so they both shared similar room condition.
 

thewas

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I should also add that during listening comparison test R3 was mounted on a stand sitting side by side with F208 so they both shared similar room condition.
I didn't doubt that, I meant that a standmount loudspeaker has inherently a different bass room response due to his different positions (usually lower and more than one) of woofers.
 
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QMuse

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I didn't doubt that, I meant that a standmount loudspeaker has inherently a different bass room response due to his different positions (usually lower and more than one) of woofers.

Sure, that is exactly how I understood your post. :)
 

Ron Texas

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Although I haven't measured in-room response of R3 during that test (I was hoping for R7) I have listened F208 and R3 side by side and bass coming from F208 was MUCH more convincing and deeper. Room was app 25m2 and R3 was struggling to fill it with sound while F208 did that effortlessly and with authority. Comparing NFS charts IMHO doesn't give you a good idea what kind of bass response speaker is really able to provide.

I wonder about this result although I agree with your statement about NFS charts. That room is not large, at least by US standards. My LS50's with two L12 subs fills a room of the same size with ease. Perhaps it's not fair to compare stand mounts against big towers which cost 2.5 times as much unless the stand mounts are augmented with subs. Needless to say integrating subs can be a pain. The difficulty is often overlooked by our technically savvy crowd.
 

QMuse

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I wonder about this result although I agree with your statement about NFS charts. That room is not large, at least by US standards. My LS50's with two L12 subs fills a room of the same size with ease. Perhaps it's not fair to compare stand mounts against big towers which cost 2.5 times as much unless the stand mounts are augmented with subs. Needless to say integrating subs can be a pain. The difficulty is often overlooked by our technically savvy crowd.

I'm sure they do, with the help of your subs, but R3 without subs was struggling to fill that room with bass while F208 did that effortlesly.
 

vavan

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never heard r3 but f208s can rumble my 25 m² room and shake my couch if fed with bass heavy material
 
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