The green line has more smoothing maybe?
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?
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.Is that a Revel Performa M20 up on the wall unit next your TV?
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.@amirm - Did you use the "Bass Numerical Optimization" method that you later added to The Revel F328Be Review for the F228Be review? Thank you!
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:@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.
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.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?
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.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.
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?
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:
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).
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?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.
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.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.
He currently measures +/-90° horizontal and +/-45° vertical.You got your ears on, JA?
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.
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?