- Thread Starter
- #361
Answer is revealed in the Revel F35 review just posted: https://www.audiosciencereview.com/forum/index.php?threads/revel-f35-speaker-review.12053/
I wasn’t trying to be rude. But, the reality is that just two units tells us nothing “useful” about the manufacturing sampling variation - unless only two units were made of course. Suppose a 1,000 units were manufactured and you test two and two of them are good. Assume the distribution is bimodal (only “good” = meeting specs or ”bad” = not meeting specs). The variation could still be anywhere between 998 bad & 2 good to 1,000 good and 0 bad. If you want to argue that my example does indeed say “something” about the variation - then I’ll concede that is true. However I don’t think it’s a very “useful” something - certainly not enough to warrant changing people’s mind about making purchases. I’m simply making an argument that, statistically, drawing any meaningful conclusion about manufacturing variability on a sampling of just two units could be completely wrong.I said some. As in better than nothing. You'd be surprised at how bad it can get even within a single pair of speakers.. Not that I'd expect something like this KEF to fall under that. Anyhow, doesn't matter.
Random aside, but one thing I don't think that has been mentioned in this thread with regards to the bass is that KEF includes a two-step port bung.
Though I did not measure the effects when I had the speaker, I do remember subjectively it had a significant effect. With my own placement nearish to the front wall, I thought using the outer ring of the port bung sounded cleanest without losing too much bass. Here's the vague image from KEF's manual, in which they seem to suggest using the port bungs for placement close to wall.
View attachment 54329
I did not need this with EQ and a sub, but it could be valuable for cleaner sound for those without a sub who plan to keep the speakers near the wall.
Could you confirm if using both bungs seals the cabinet?
The included double bung certainly does it on my LS50, don't have a R3 though.Could you confirm if using both bungs seals the cabinet?
Could you confirm if using both bungs seals the cabinet?
They completely seal the back of the port. If your concern is about the bungs making it behave similar to a sealed box, I can't give you a confirmation without measuring it.
All I can say is I do play a lot with the positioning of the cabinets and put the bungs in and out just for the fun and testing (my current liberty of movement for the speakers is ridiculously small until I make room modifications and change furniture). They are an extremely useful tool for special cases. Once I get final placement, manual PEQ or Dirac and subwoofer, there won't be any need for them...or at least for swapping between no bung, half bung or full bung.
@tuga Ohh that's quite interesting. Did you keep the ports open on the Left Speaker and closed on the Right Speaker?
I second that, when we used to live in the rented accommodation my LS50s were placed close to the rear wall (~25cm) and I had to use the bungs all the time. Now they are at least a metre away so no bungs.The included double bung certainly does it on my LS50, don't have a R3 though.
I find it interesting that Amirm is finding that this speaker sounds 'uninvolving'. After a very respected audio engineer told me he discovered that the coax driver series that KEF use here measures phenomenally well a couple of years ago when the KEF Blade was released, I went to hear a set local to me in a well acoustically treated room.
Awful.
I wish I knew why. I knew they measured very well.
Tried an A/B test against an ATC SCM11. Ha! No comparison. Subjective comments are just that, but........
The KEF sounded dead, boring and lacked any kind of drive some how. Even with the bass EQ'd up, it just didn't sing. Detail seams to be there, but not in the upper mid.
Amirm: I have a sneaky suspicion that if you ran a multi tone test- they will show up that coax is no good. Remember, you subjectively liked the JBL 305......and that has less bass. I know you know there is more to this speaker game
What you heard was the Kef midrange vibrating and modulating the tweeter. A problem with all loudspeaker drivers with the tweeter in center of the midrange. The midrange membrane is acting like a waveguide to the tweeter. As the membrane is vibrating , the waveguide for the tweeter constantly changes, changing the frequency response of the tweeter when playing music. The measurements may look fine, though.
What you heard was the Kef midrange vibrating and modulating the tweeter. A problem with all loudspeaker drivers with the tweeter in center of the midrange. The midrange membrane is acting like a waveguide to the tweeter. As the membrane is vibrating , the waveguide for the tweeter constantly changes, changing the frequency response of the tweeter when playing music. The measurements may look fine, though.
The measurements are made with static signals. Music doesnt work that way. An acoustic piano plays all the frequencys at the same time, meaning it will exite for example 30-20000 Hz at the same time.If you think that modulation is not visible in frequency response nor in THD measurement why do you think it is audible at all?
The measurements are made with static signals. Music doesnt work that way. An acoustic piano plays all the frequencys at the same time, meaning it will exite for example 30-20000 Hz at the same time.
The problem with coaxial drivers can be seen with measurements playing 300 Hz tone and 8000Hz at the same time, at high levels.
Im sorry to say there is still a minor problem. Just consider the wavelengt of 10000 Hz . How much does a tweeter have to vibrate to play that frequency ?Although that might be a problem with the LS50/Q150, in the R3/300 the midrange crossover is 400hz so the cone is moving 2-3 mm, hardly enough to present a problem.
It would be interesting if Amirm could do a test like that.Are you trying to say coaxial drivers would fail IMD multitone test?