Wilson Audio Haters

@erik_squires

I am sure you are right that AMT can be built to avoid compression however doesn’t this result in a transducer that is too large a diaphragm for the frequencies they transmit?

In short: Eliminate the compression means you begin to have directivity problems.

Rule of thumb is that the diaphragm should be no bigger than 1/2 the wavelength or you start getting beaming at that frequency and for even higher frequencies (shorter wavelengths) you get off axis lobing.

Lobong creates a spurious 3D effect where certain sounds come from the ceiling and some from the side walls depending on the frequency. An overly tall tweeter will have serious lobing in higher frequencies in the vertical axis but less so horizontally - it is the weird vertical response that gives spurious 3D effects while listening to music with a variety of frequencies - nothing to do with the source and everything to do with bad design and poor implementation.

Technical details explaining why you get spurious 3D effects with this design:

Please refer to the article and charts at this link

http://www.acousticfrontiers.com/20131129controlled-directivity-speakers-open-up-your-acoustic-treat...

The AMT folded ribbon driver in the PL 200 is 3 inches tall. At 6000 Hz it has a KA of 5 in the vertical and at 12000 Hz it has a KA of 10. These frequencies are within the important musical range. You can see on the polar plots how serious of a problem these speakers have in the vertical axis.

Bo, Isn't Tru-Fi chocolate brand?
How it's compared to Lyndt or Godiva?

Is Tru Fi the same thing as Tuning? It certainly comes across that way least in terms of the dogmatism, mysteriousness, hostility and prostelyzation if not in actual implementation. Could it be that Tuning has spread to Europe? 

😧

shadorne,

Let's say everything you suggest is true about AMT folded ribbon drivers. I still prefer the MA PL500's over any Wilson speaker I've ever owned or heard. I've learned after making a generalization about Class "D" amplifiers that unless I've heard every component out there, it's hard and/or impossible to say how it sounds based on specifications or design.

@shadorne You say "problems’ as a speaker designer I say "possibilities."

The directivity of an AMT is different than a dome or ring, but if you are going to attack it, you will attack all line or planar sources, including ESL speakers from Martin Logan or Sanders, Quad, blah blah. not to mention most horns as well.

You are conflating compression with directivity and lobing. Three different things.

Let’s get compression out of the way first. When you add X dB to the input but the output is not uniformly X dB louder. About the only reviews that have this routinely are the one’s from

speakermeasurements.com

So I stand by my original statement, the best AMT's can compete with the best of any other type of tweeters in terms of compression.

Let’s discuss the rest. Lobing isn’t really caused by a single driver but how it interacts with another. It is caused by one driver interfering with another at different angles over the frequencies at which they are both working. This can be pretty complicated as the acoustic distances between 2 drivers varies in three-dimensional space. This is why lobing is a 3D problem, and why many manufacturers align their drivers in a vertical line, to minimize the complex and unpredictable (but not impossible to simulate) nature.

A single driver can not lobe. Single driver and single panel ESL speakers  are immune from this behavior but any 2 drivers can lobe, it is not an issue of planar vs. dome at all. It’s an issue of the acoustic centers not being aligned and crossover design choices.

Any time you have 2 or more drivers which overlap in the frequency domain and are not coincident in 3D space lobing can occur. With a theoretically perfect crossover, lobing disappears, but no one has made this yet. Admittedly the Joseph Audio 100 dB/octave crossovers come close. Co-axials are another nearly perfect solution to this problem.

Lobing is sometimes deliberately caused. For instance, the super-expensive, super-ugly B&O Beolab 90 takes advantage of this, and uses DSP to stagger the delays between similar drivers. Also a technique used in professional arrays. In the Beolab only dome’s and cones are used, but it’s been demonstrated many times they can "lobe" very well.

So with that out of the way, neither very broad nor very narrow drivers are "best."

Narrowing the angle of radiation can be VERY beneficial. Time domain problems, and therefore frequency response, at the listening location are greatly reduced by using larger diaphragms and have the perception of transparency and neutrality in spades. Anyone who has spent time listening to a good AMT or larger ribbon driver will attest to this.

Sure, if you are designing a speaker that needs extremely broad radiation in the vertical and horizontal plane, a broad frequency, planar driver is not going to be for you. That’s a reasonable trade-off, but neither should be judged by the Audiophile Gods of All That is Good as an absolute measure of "better."

Unfortunately, I find your prejudices unjustified. You should of course buy and live with whatever drivers you want to but AMTs in general deserve a better treatment than you are giving them.

For the top end, I really encourage anyone who can listen to the Gryphons to spend some time with them and compare to some of the low-end "giant killers" being touted as superb.

Best,


E