Colonel7
Addicted to Fun and Learning
Don't see waterfalls like that often...looking forward to hearing these this weekend!
Looks so familiar. I'd just say we BMR / BMR Tower's cabinet maker also make many other brands that cost much more than the BMR / Tower. The finish quality is similar although several samples I've seen has way fancier cabinet design than ours.I would love to see the BMR Tower measured by @amirm. The shipping carton method looks a lot like the Revel F328Be minus the aluminum case. Looks like an awesome speaker. I look forward to trying it.
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Logistics make testing towers difficult. Shipping is very expensive. The difficulty of lugging heavy towers through his house or mounting them on the klippel is something I can appreciate.I would love to see the BMR Tower measured by @amirm. The shipping carton method looks a lot like the Revel F328Be minus the aluminum case. Looks like an awesome speaker. I look forward to trying it.
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The little blip is really more like 2 dB, and it doesn't show up on any of my measurements. I've attached my on-axis plot of one of the towers. I get pretty good resolution in the 600 Hz region. See below.Everything else is flat (as it should be in 2021 made loudspeaker) but 3dB isn't a small peak.
Port resonance usually causes dip on axis so that seems unlikely to me. I'd check that more thoroughly if i had the speakers on me.
And to keep things in perspective, compare the$3,700 BMR tower with the same type plot James made of the $16,000/pair Perlisten tower:The little blip is really more like 2 dB, and it doesn't show up on any of my measurements. I've attached my on-axis plot of one of the towers. I get pretty good resolution in the 600 Hz region. See below.
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Logistics make testing towers difficult. Shipping is very expensive. The difficulty of lugging heavy towers through his house or mounting them on the klippel is something I can appreciate.
The little blip is really more like 2 dB, and it doesn't show up on any of my measurements. I've attached my on-axis plot of one of the towers. I get pretty good resolution in the 600 Hz region. See below.
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The hard part may be getting the Klippel Near-field Scanner (NFS) to accurately measure the bass response as the 8" ScanSpeak Revelator driver is a bit of a distance from the RAAL tweeter.
The F328Be came from a supplier to his business and did not have to be shipped back to a member. You should note his remarks about the difficulty of testing towers.The BMR Tower weighs 72lbs. The Revel F328Be that @amirm tested weighs 112lb. The BMR Tower is a baby in comparison. I'm sure he could test it nicely in the garage. I doubt his wife would volunteer to help move it upstairs.
The hard part may be getting the Klippel Near-field Scanner (NFS) to accurately measure the bass response as the 8" ScanSpeak Revelator driver is a bit of a distance from the RAAL tweeter.
It was a coin flip on who to ask for a review. At the time, I thought the Audioholics measurements would include a full spin. I happen to be a fan of James'breadth of musical taste, and I thought from a subjective standpoint the tower might be a better fit given its design objectives.Not a problem at all.
I can get great resolution at 1kHz w/ 5-6ms in my room using OmniMic. To get it down to 200Hz, I need to move a few things around (less reflective) and use longer gate time.To get a decent resolution below 1kHz you need at least 10ms gate time. Now i don't know what am i looking at in this graph but it doesn't look like anechoic and certainly not like high resolution measurement. Larson's measurements are much better in that regard.
600Hz is a 57cm wavelength, so I'd think this would depend on relative distances between mic, driver(s), & port(s). Are you talking about merging nearfield measurements?Agreed. With the port being on the front, you should have a dip if the port is the culprit. Rear ports result in a peak. Usually not from the port itself but from the port leaking internal resonance.
Larson's review of the BMR Tower is up at Audioholics.
Nice work, @Dennis Murphy - the polars are simply outstanding.
Interesting, it actually seems to measure a bit better(more even) than the Perlisten tower.And to keep things in perspective, compare the$3,700 BMR tower with the same type plot James made of the $16,000/pair Perlisten tower:
Praxis and Omnimic (both by the same designer) gradually lengthen the sampling window as you get below the 800 Hz point or so. By 200 Hz, the response is purely room. I'm not sure how this affects resolution at 600 Hz, although all those little ripples on my measurement suggest that no smoothing has been invoked. Anyhow, I don't want to get into an argument about this. Right now I'm in quasi-panic mode trying to get everything ready for the Capital Audio Fest. When it's over, I'll measure the bajeezus out of each tower and see whether I can figure out what, if any thing, is going on.@alexis Every software applies more smoothing when doing gated measurements as you get closer to gate frequency/time. With gate of 5-6ms you get something like 1/6 octave smoothing below 1kHz. If there is need for high resolution measurements (and there is at least when you are developing a loudspeaker) you need to get to at least 1/24 octave smoothing.
Right now I'm in quasi-panic mode trying to get everything ready for the Capital Audio Fest.
For extra credit, ask any professional reviewers who stop by to ID which speaker is +2dB at 600Hz, at least after they hear a couple tracks unprompted. I'm sure the analysis will be enlightening about the real-world audibility.Right now I'm in quasi-panic mode trying to get everything ready for the Capital Audio Fest. When it's over, I'll measure the bajeezus out of each tower and see whether I can figure out what, if any thing, is going on.
I do appreciate that your comment is indeed constructive. Please don't take my posts as an unreasonable defense.To get a decent resolution below 1kHz you need at least 10ms gate time. Now i don't know what am i looking at in this graph but it doesn't look like anechoic and certainly not like high resolution measurement. Larson's measurements are much better in that regard.
Now look, i don't mean anything bad by writing what i did, but it is there. There is so much good stuff going on in this loudspeaker to be dismissive of one constructive critique that is aimed on making the preformance even better. I also don't want to make an auction about how high is that peak. It is observable in polar map measurements as well. I'd be curious what that resonance is if i was to put my signature on that speaker, doesn't mean you should be to.
Why didn't Larson post spinorama, as he did with BMR Philharmonitor ?
The Philharmonic BMR Towers were measured in free-air at a height of 4 feet at a 2-meter distance from the microphone, with the microphone raised to a 7.5’ elevation that was level with and aimed at the tweeter center. The measurements were gated at 8-milliseconds. In this time window, some resolution is lost below 400 Hz and accuracy is completely lost below 200 Hz. Measurements have been smoothed at a 1/24 octave resolution.
This does suggest that the various graphs showing the 600 Hz bump have a greater visual impact than it's sound does to at least one listener.I did do near-field measurements of the drivers and port, and that hump does look to be an artifact of the port. It's not significant enough to be audible …