Flat Anechoic Measured Frequency Response Speakers

Jkalman, in my opinion Robert E. Greene of the Absolute Sound (also a high-ranking professor of mathmatics at UCLA) has a genuine understanding of what matters when it comes to a loudspeaker's in-room performance. Here is a link to his website:

http://www.regonaudio.com/

See in particular the measurement supplements to his TAS reviews of the Gradient Revolution and Jamo 909, and the measurements of his Harbeth monitor 40 (that page is currently "under construction" but he has some measurements posted).

The "target curves" that you see in the Gradient and Jamo supplements are similar to a target curve published by Bruel & Kjaer, which I can't find online but it's basically flat below 100 Hz and then slopes down by a little less than 1 dB per octave from there on up. I presume this is a non-time-gated measurement from the listening position.

Duke

Drubin,

You are referring to what Paul Barton said concerning Toole's studies? I've heard that people prefer sizzle on top, not roll-off. Do you have a quote? Thanks.

I think one of the misconceptions about the Toole research was that he trained listners to pick a certain loudspeaker over another. Actually, what they did was to evaluate and train listners to hear various types of distortions added to program material. As well, this was for research purposes, not in any way a marketing ploy to sell a particular brand of loudspeaker.

Also, to add a couple of items to the off-axis dispersion discussion: This is generally accepted to be simply good loudspeaker engineering. Most of the Canadian companies that use the NRC or NRC-based research see this as critical to proper loudspeaker design. But in addition you'll find that Doug Schneider, who assists in the loudspeaker measurements at SS!, and John Atkinson at Stereophile (has measured many speakers), have come to agree that smooth, controlled off-axis dispersion equate with good sound in real rooms.

Lastly, I actually discussed the Athena Project with Paul Barton at CES this year. What they determined was not so much that a midbass bump was desirable, but instead a smooth rise in the bass starting at 200Hz and going down to 20Hz -- I think it was about a 6dB rise over that range. The key being a _smooth_ rise. Anthem is actually basing their new room correction software on this target curve. As for the top end, simply google the EBU target curve and you'll find a good graph.

Hope this helps.

Jeff Fritz
Managing Editor
The SoundStage! Network

Jkalman, no I don't have a quote. I was making an assumption based on the consensus standard for these things.

Actually, what they did was to evaluate and train listners to hear various types of distortions added to program material. As well, this was for research purposes, not in any way a marketing ploy to sell a particular brand of loudspeaker.

The testing also taught listeners how to identify changes to different ranges of the frequency response. Though that could be considered added distortion. I read an interview where Voeks discussed the process. If people couldn't learn to identify changes to frequency response, and didn't identify which one was incorrect, or not flat, they weren't used for the blind testing. People with suboptimal lower and higher frequency hearing were also excluded. I don't think any of this was a ploy, but I do think it is cherry picking, and that will likely affect the final outcome.

Is it a good thing or a bad thing? I don't know. It is good that speakers have some type of technical boundary within which they should measure and that people have tried to shed light on that boundary. It does make me wary though as to exactly what those boundaries are and how much they can differ between different individuals. Especially if those individuals had no training.

I'm planning on experimenting with my own setup to see what I like best. Part of that will include speakers that measure extremely flat. I would consider Revel Ultima2 Salons to be one of the speakers worth experimenting with, but no one around me is carrying them to allow me to demo them at a store... ATC is another one I've been considering (the Pro versions). The Magico Mini II as well.

As for the top end, simply google the EBU target curve and you'll find a good graph.

If you could give a link to something I would appreciate it. I tried Google-ing "EBU target curve" and I didn't get anything useful on the first bunch of pages.

I have been trying to find the quote someone else I know got their information from concerning the "top-end sizzle," but so far no luck (he might have been wrong about the top-end, which is exactly why I want to find some quotes on it - I'm not being cantankerous or anything, just looking for a source).

Thanks.