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Revel F208 Tower Speaker Review

amirm

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#1
This is a review and detailed measurements of the Revel F208 speaker. It was kindly purchased by a member and drop shipped to me for measurements. Revel F208 costs $2,500 each or US $5,000 for a pair.

Note: our company, Madrona Digital is a dealer for Revel speakers. Feel free to read as much bias as you like in this review.

The unit as tested is in piano black which gives a luxurious feel to the unit. Alas, the unit was too heavy for me to lug it up to my listening room so you have to settle for a plastic wrapped version of it in my test "lab:"

Revel F208 Tower Speaker Audio Review and Measurements.jpg


There was a sturdy sheet of plastic covering the front which I took off but left the rest of the plastic on it to protect it as you see in this shot:

Revel F208 Tower Speaker Audio Review Back panel binding posts.jpg


I went through a bit of hell trying to figure out why the speaker would not plays the highs at first. After hours of trying to figure it out, and losing out a day, I realized it was a simple thing: the bar wires I was using would not always allow the shorting bar to do its job. I have to use a bare wire as to lower the interference around the speaker as the robotic arm moves the mic around. Anyway, I have to take the speaker to the owner in an hour so no time for listening tests either.

This speaker was the heaviest I have tested and despite having that wonderful lift you see in the first picture, it was a killer to unpack and move around.

I played with the bass compensation and it does what it says: if you set it to boundary, it lowers the bass level. I did not test the tweeter one but I suspect it does the same. An array of power resistors behind that panel makes these simple level changes.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

All measurements are referenced to the tweeter axis with frequency resolution of 2.7 Hz. I used a high number of scans (over 1000 measurements).

Spinorama Audio Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker can be used. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

Revel F208 Twoer Speaker Spinorama CEA2034 frequency response audio measurements.png


If you look at Harman measurements, you see that they show a lot more bass output and smoother response:

Revel F208 Twoer Speaker Spinorama Harman frequency response audio measurements.jpg


After spending countless hours on the measurements, I am convinced Harman measurements like above are in error. My in-room response that doesn't use any of the Klippel mathematics is also in conflict with their measurements. If you look at the measurements for Revel Salon 2 speakers, you see that the older one performed in 2007 is the same as above but the 2017 one is very similar to what I got for F208: https://speakerdata2034.blogspot.com/2019/03/spinorama-data-revel-ultima.html

1588966261478.png


Notice the sharp drop in low frequency in the second measurement below. And bit of scalloping in high frequency response which I am also getting in F208.

I was puzzled that the on-axis response was not as smooth as I expect Revel speakers to have. That disappeared when I looked at the rest of the measurements starting with predicted in-room response:

Revel F208 Twoer Speaker Spinorama CEA2034 Predicted In-room Response  frequency audio measure...png


Wow! With no DSP this speaker managed to get such balanced and smooth response. It appears that the off-axis response is tuned to counter the on-axis response as we see here:

Revel F208 Twoer Speaker Spinorama CEA2034 frequency response early reflections audio measurem...png


This makes the speaker fairly room independent and sharply increases your chances of putting this in any room and enjoying accurate sound reproduction.

Distortion levels are very much controlled:

Revel F208 Tower Speaker distortion percentage THD audio measurements.png


Ignore the rise in very low frequencies as that goes beyond the speaker's ability to reproduce. The rest shows no "acoustic events" other than a bit of wiggliness between 100 and 200 Hz:
Revel F208 Tower Speaker distortion THD audio measurements.png


In this calibrated graph where the range is 50 dB, I like to see nothing but blank space for distortion and the F208 gets there with the exception of the lower frequency range.

Impedance test shows dipping to 3.5 ohm so you better have a high current amplifier that doesn't mind such loads:

Revel F208 Tower Speaker Impedance and phase audio measurements.png


Horizontal directivity diagram shows very wide response which means you don't have to sit in a vice to get good sound:

Revel F208 Tower Speaker Horizontal directivity frequency response audio measurements.png


And if you left the side wall reflections bare, you should get wider image. The inclusion of that mid-range gives good dispersion to whopping 100 degrees!

Vertically the situation is not as good as we typically see in non-coaxial designs:

Revel F208 Tower Speaker Vertical directivity frequency response audio measurements.png


I am in a hurry so could not optimize the CSD plot so here it is:

Revel F208 Tower Speaker CSD waterfall audio measurements.png


I wanted to see if I could diagnose the up and downs in high frequencies so ran this 3-d plot:

Revel F208 Tower Speaker diffraction loss frequency response audio measurements.png


The problem could also be the mid-range still going as we see in the hot area below the tweeter.

Speaking of that, i had time to run the lower bit by itself:

Revel F208 Tower Speaker Woofer distortion and frequency response audio measurements.png


But am out of time to calibrate the tweeter response and overlay it.

Conclusions
I expected textbook on-axis response but did not quite get that out of Revel F208. But the speaker came to its own with stellar predicted in-room response which is what ultimately matters as you hear both direct and indirect sounds. Off-axis summed response also looks superb. People ask me if they should buy Revel speakers. I always tell them they should for two reasons:

1. You can put them in just about any room and they sound great due to off-axis response being carefully designed.

2. They are the only speakers designed and released with double-blind listening tests.

I wish I had done my listening tests so I could make my own judgement with F208 but I don't have time as I have to pack and drive them to the owner in a few minutes. But based on measurements, I think they come very close to my Revel Salon 2. If so, they should sound wonderful.

I am going to put Revel F208 speaker on my recommended list. I know, shocker. :)

-----------
As always, questions, comments, recommendations, etc. are welcome.

Killed my back moving this speaker around so had to hire someone to get rid of all the weeds as @Thomas savage is not available. He is charging me $100/day so on top of the expenses for this site, I need money for that. So please donate as much as you can using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

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Blumlein 88

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#3
Just eyeballing it looks like is the best result you've had so far.

I was going to ask you drop them to me to confirm your results. I'd promise the owner would get them in less than two years. But looks like you are on a deadline. Someone will be very happy I think with their new purchase.:p

Well MZKM posted the same time I did. Looks like the Genelec 8341a and KEF R3 edge it out on the score.
 

Thomas savage

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#4
This is a review and detailed measurements of the Revel F208 speaker. It was kindly purchased by a member and drop shipped to me for measurements. Revel F208 costs $2,500 each or US $5,000 for a pair.

Note: our company, Madrona Digital is a dealer for Revel speakers. Feel free to read as much bias as you like in this review.

The unit as tested is in piano black which gives a luxurious feel to the unit. Alas, the unit was too heavy for me to lug it up to my listening room so you have to settle for a plastic wrapped version of it in my test "lab:"

View attachment 62502

There was a sturdy sheet of plastic covering the front which I took off but left the rest of the plastic on it to protect it as you see in this shot:

View attachment 62503

I went through a bit of hell trying to figure out why the speaker would not plays the highs at first. After hours of trying to figure it out, and losing out a day, I realized it was a simple thing: the bar wires I was using would not always allow the shorting bar to do its job. I have to use a bare wire as to lower the interference around the speaker as the robotic arm moves the mic around. Anyway, I have to take the speaker to the owner in an hour so no time for listening tests either.

This speaker was the heaviest I have tested and despite having that wonderful lift you see in the first picture, it was a killer to unpack and move around.

I played with the bass compensation and it does what it says: if you set it to boundary, it lowers the bass level. I did not test the tweeter one but I suspect it does the same. An array of power resistors behind that panel makes these simple level changes.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

All measurements are referenced to the tweeter axis with frequency resolution of 2.7 Hz. I used a high number of scans (over 1000 measurements).

Spinorama Audio Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker can be used. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

View attachment 62506

If you look at Harman measurements, you see that they show a lot more bass output and smoother response:

View attachment 62507

After spending countless hours on the measurements, I am convinced Harman measurements like above are in error. My in-room response that doesn't use any of the Klippel mathematics is also in conflict with their measurements. If you look at the measurements for Revel Salon 2 speakers, you see that the older one performed in 2007 is the same as above but the 2017 one is very similar to what I got for F208: https://speakerdata2034.blogspot.com/2019/03/spinorama-data-revel-ultima.html

View attachment 62508

Notice the sharp drop in low frequency in the second measurement below. And bit of scalloping in high frequency response which I am also getting in F208.

I was puzzled that the on-axis response was not as smooth as I expect Revel speakers to have. That disappeared when I looked at the rest of the measurements starting with predicted in-room response:

View attachment 62509

Wow! With no DSP this speaker managed to get such balanced and smooth response. It appears that the off-axis response is tuned to counter the on-axis response as we see here:

View attachment 62510

This makes the speaker fairly room independent and sharply increases your chances of putting this in any room and enjoying accurate sound reproduction.

Distortion levels are very much controlled:

View attachment 62511

Ignore the rise in very low frequencies as that goes beyond the speaker's ability to reproduce. The rest shows no "acoustic events" other than a bit of wiggliness between 100 and 200 Hz:
View attachment 62512

In this calibrated graph where the range is 50 dB, I like to see nothing but blank space for distortion and the F208 gets there with the exception of the lower frequency range.

Impedance test shows dipping to 3.5 ohm so you better have a high current amplifier that doesn't mind such loads:

View attachment 62513

Horizontal directivity diagram shows very wide response which means you don't have to sit in a vice to get good sound:

View attachment 62515

And if you left the side wall reflections bare, you should get wider image. The inclusion of that mid-range gives good dispersion to whopping 100 degrees!

Vertically the situation is not as good as we typically see in non-coaxial designs:

View attachment 62516

I am in a hurry so could not optimize the CSD plot so here it is:

View attachment 62517

I wanted to see if I could diagnose the up and downs in high frequencies so ran this 3-d plot:

View attachment 62518

The problem could also be the mid-range still going as we see in the hot area below the tweeter.

Speaking of that, i had time to run the lower bit by itself:

View attachment 62519

But am out of time to calibrate the tweeter response and overlay it.

Conclusions
I expected textbook on-axis response but did not quite get that out of Revel F208. But the speaker came to its own with stellar predicted in-room response which is what ultimately matters as you hear both direct and indirect sounds. Off-axis summed response also looks superb. People ask me if they should buy Revel speakers. I always tell them they should for two reasons:

1. You can put them in just about any room and they sound great due to off-axis response being carefully designed.

2. They are the only speakers designed and released with double-blind listening tests.

I wish I had done my listening tests so I could make my own judgement with F208 but I don't have time as I have to pack and drive them to the owner in a few minutes. But based on measurements, I think they come very close to my Revel Salon 2. If so, they should sound wonderful.

I am going to put Revel F208 speaker on my recommended list. I know, shocker. :)

-----------
As always, questions, comments, recommendations, etc. are welcome.

Killed my back moving this speaker around so had to hire someone to get rid of all the weeds as @Thomas savage is not available. He is charging me $100/day so on top of the expenses for this site, I need money for that. So please donate as much as you can using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
There's a support group for all those affected by amirm's gardening needs. Many have run away never to be seen again . ( Partly true , at least one guy just ran for his life )

I'm not sure what's worse , amirm's weeds and gross neglect of his garden or some of you internet crazies I have to deal with .

At least with the weeds you can see what's Infront of you .

Either way I don't get paid enough!
 

franspambot

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#5
Thanks to Amir and the owner for this review. Many of us are interested in the Performa3 line so this is super helpful and very much appreciated. What a pleasant surprise for this to pop up!

As someone torn between the 3 and be lines, the measurements here seem to show great value compared to the promises of the latter. I'm guessing the major real world differences will be in bass output and slightly better sensitivity with the be. The in-room response here looks so good!

It also seems that the R series from KEF has a chance to distinguish itself with its vertical directivity ability. That coaxial design is something else. Would love to see the R11 or R7 compared to this.

Can't say this enough: thank you!
 
Last edited:

Blumlein 88

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#7
I think this a good comparison for how to use the charts for quick comparisons. Had I looked back at the KEF R3 and Genelec 8341a the charts would have shown they were better than this fine result from the F208. The red and blue lines at the bottom of the graph do reveal quite a lot even for speakers as close as these three.

KEF R3
1588968486698.png


Genelec 8341A (the best result)
1588968533754.png

And the F208 just above. Pardon the redundancy.
1588968574915.png
 

StevenEleven

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#8
I’m skeptical of Harman’s in-house measurements as well. Doesn’t take much expertise (and indeed I have very little, if any, I’ve read F. Toole’s book and that’s about where I am). Just eyeballing the graphs is enough to raise doubts in a skeptical person’s (that would be me) mind about Harman in-house measurements.

However, based on these measurements, that is sure enough one $5k pair of speakers, worth full freight, worth every penny, if that level of refinement is within one’s desires and budget. It doesn’t take much expertise to figure that out either—just the data and information on this web site. :)

Thanks for the review (and the ensuing comments of the [mostly] expert peanut gallery to come), always high entertainment and fun to read.
 

MZKM

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#9
Looks like the Genelec 8341a and KEF R3 edge it out on the score.
The F208 is better than the R3 if you use a great subwoofer for both.

8341A vs R3 vs F208 Breakdown:

NBD_ON (lower = better) : 0.31 vs 0.34 vs 0.33
NBD_PIR (lower = better) : 0.22 vs 0.25 vs 0.25
SM_PIR (higher = better): 0.93 vs 0.89 vs 0.9
LFX (higher equals better): 1.55 vs 1.55 vs 1.6
 

MZKM

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#11
Without a sub, the KEF R3 is better (crazy how the bookshelf has more bass).

For $3000/$4000/$5500 you have the KEF R5/R7/R11; we don't know 100% if the performance is just as accurate though..
 
Last edited:

Blumlein 88

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#12
The F208 is better than the R3 if you use a great subwoofer for both.

8341A vs R3 vs F208 Breakdown:

NBD_ON (lower = better) : 0.31 vs 0.34 vs 0.33
NBD_PIR (lower = better) : 0.22 vs 0.25 vs 0.25
SM_PIR (higher = better): 0.93 vs 0.89 vs 0.9
LFX (higher equals better): 1.55 vs 1.55 vs 1.6
Yes, I did notice that. I'd also think without such a sub in larger rooms the 208 might have an edge in actual usage. Just from having more square inches of woofers.
 
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#16
Seeing these great Revel reviews makes me curious about how well the Infinity R253 or R263 would compare.
 
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#17
Very exciting to see the Revel quality control and the promise to tune and match all speakers to the reference holds true! (Already Concerta2 are tuned and controlled). To my eyes this is spot on the same as Harman measured - entierly within acceptable variance. Then the base measurements are probably wrong as anechoic chambers with their calibrations are not always great at low frequencies. Either way there is just enough base for subwoofer integration (as Dr. Toole told everyone to do for good base) + no low-end extension means more headroom.

We can not ask for such service on "cheap" Harman speakers, but I wish I could be this confident about JBL Pro or JBL Synthesis speakers. @amirm measurements of JBL 705 should be a wake-up call to Harman - quality control is as important as great design!
 

Sancus

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#18
The F208 is better than the R3 if you use a great subwoofer for both.
It seems like the R3 vs F208 would end up being more of a choice about whether you prefer wide or narrow directivity than anything else, since they differ so significantly in that area. And I suppose whether you care about a more flexible vertical listening window or not.
 

napilopez

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#20
Thanks Amir!

I think the key thing this speaker and other revels do so well is controlling directivity and maintaining wide directivity. On most speakers there is a clear trade-off in one for the other. Just look at the polar plots or how much lower the DI curves are for the f208.

The Genelec, which isn't even super narrow, is only out to about 60 degrees compared to 75 degrees for the revel. In my experience these are very audible differences. Whether or not you like the wide directivity sound it's clear revel does it better than almost anyone.
 
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