What’s up with the trough between 80 and 300, looks like more than a room mode... can you try pulling one speaker out into the room and measuring with mic at ~1m? Other than that you have very impressive in room bass response from those speakers! 25 hz!
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Revel F208 Tower Speaker Review
- Thread starter amirm
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Boundary switch turned on is probably a good setting, for right speaker it looks close to below model of three same boundary distances, can you get it arranged so that its closer into the corner and so that the two other distances is 1/3 and 2/3 than center distance in middle between the dual woofers down to the floor, get them three distances within 1/3 and 2/3 difference will improve that nasty suchout as you see in below animation, above 270Hz mid take over and sits in a longer distance to floor so that is a okay difference. Spreadsheet for practical simulation below is the "Baffle Diffraction and Boundary simulator" at this link: http://audio.claub.net/software/jbabgy/jbagby.html
I was thinking that there are a lot of useful resources scattered around the forum, it would be nice to put them in a dedicated thread otherwise they will be lost/difficult to find back.
Bear123
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I know there has been discussion as to whether the low frequency measurements by the Klippel on the large tower speakers are accurate. I for sure don't know the answer. The Klippel spin shows -3 dB at 60 Hz, and about -15 dB by 30 Hz. The owners in room response is +8 dB at 25 Hz. One of those two measurements can't be right. My Revel F36 are flat to 25 Hz in my 2525 ft^3 room, which would also not be possible with the Klippel measurements of the very similar F35. I figured it was possible the F36 extends lower since they aren't the exact same speaker. But the results for the F208 don't make sense.
Klippel NFS spin: -15 dB @ 30 Hz
In room: +8 dB @ 25 Hz.
???
Klippel NFS spin: -15 dB @ 30 Hz
In room: +8 dB @ 25 Hz.
???
Might be worth shooting JBL/Harman an email to see if they can provide some insight as to the differences.
I've found that measuring both speakers together gives the best results, when I tried EQ'ing each individual speaker and then re-measuring both together they ended up cancelling each other out a lot creating more troughs...so I've had best results by just always measuring & EQ'ing with both speakers running, so treating them as a whole.
Looks like the boundary switch helped, but you'd want to overlay a Harman curve to be sure it's in the right ballpark (which you've probably done). You still need to EQ up that trough that I talked about in my last post, between 130Hz and 230Hz. I have the same trough with my speakers except it's shifted by 30Hz to the left. I use "2 opposing Low Shelf Filters" to boost up that area, felt like the gentlest & broadest way of doing it, (plus it gave me the option to leave a 2dB low Shelf Boost extending down to 0Hz, but you don't need that part).
Why not
1) we can see his right channel is situated tight into a corner.
2) say longest room dimension is less than 12 feet and building is modern air tight high pressurization one then those gains are absolute possible.
Also have you noticed how post 82 F208 measured in room response makes sence to Amir's low end reponse for F208 into post 118.
OP
- Thread Starter
- #148
I did. Months ago. Asked for the same speaker to be tested in their chamber and sent to me for measurements. I even offered to pay for shipping when asked. Unfortunately communications went dead from then on from my best friend there no less. A second contact started the same way, and went dead just as well. I asked my friend one more time a couple of weeks later, again no response.
Let's remember that there are also two very different looking measurements from Harman on Revel Salon 2 as well as I showed. So there are issues involved here that we are not privy to.
At this point, this is their issue to try to resolve, or not. I have pulled every string I can. I stayed up late trying to measure and remeasure to find the cause but I cannot.
FYI I used to move heaven and earth for my contacts at Harman and they would do the same for me. It was that good of a relationship. What has happened and why, I can't figure out.
Maybe you guys should contact them, give them the link to the review and ask them to explain.
Thanks input have traced that cyan curve overlaid below and unfortunately it happen be of that same family as the official year 2007 spinorama data Harman did back then for F208.
Impressive, but I'm not exactly sure what this means:
"An In-Room measurement of the Revel f208 was generated using RoomEQ Wizard, a UMIK-1 calibrated microphone, and multiple listening positions through the room. This method helps to reduce the modes introduced by the room itself and provides an accurate indication of the overall speaker response."
I think it means that is an averaged response, and I'm pretty sure they averaged out all of the dips and peaks one normally sees in an unsmoothed in-room measurement. I've never seen one that good.
I agree, probably the second graph is the correct one (shows the effect of boundary switch):
Can't really know other than speculate about it and that the current situation between good friends is sad
now please don't eat me when i say that i think Amir wasn't so diplomatic at a certain stressing time when a Harman employed member asked to your Klippel operating situation over in Kali Audio IN-8 thread, can it hang together than sinse that case at Harman they collective agreed that cooperation to ASR should be cooled down a bit, but also if some of their official published performance curves is intepolated a little notch too the good side its a stressing situation for them you got that for us wonderfull precision analyzer 
wannarock2
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stepping out of the deep weeds here for a second to say i love my F228Be’s (ツ)
OP
- Thread Starter
- #158
My communication with them was prior to Kali testing.Can't really know other than speculate about it and that the current situation between good friends is sad
Room measurements can hardly be transferred to the free field behaviour of the loudspeaker - especially in the low bass.
Each boundary surface (floor, side wall rear wall) can contribute up to +6dB sound pressure increase and each room mode can contribute even more (+10-20dB).
In your example a large part of the 27Hz sound pressure increase could be caused by a room mode (6-6.5m room length).
Yeah, the Performa3 series has the best vertical dispersion I've seen for speakers that aren't coaxial. That's why the M105 is one of my favorite speakers of all time, you can have them on the 24 inch stands and stand above the speakers and the intelligibility is nearly as good. It casts a massive image both to the sides and also vertically.
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