Flat Anechoic Measured Frequency Response Speakers

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.

Search Yahoo for "Listening conditions for the assessment of sound programme material" and the EBU article will come up.

I understand your suspicion re: the Toole research, but one thing that the EBU study shows is that there is much consensus about many of these issues. Take the off-axis response issue. EBU doc states "Frequency response curves measured at directional angles +10° and +30° should not differ from the frequency response measured on the main axis (directional angle = 0°) by more than the following permissible deviations:" ...and then it gives the data.

Also in that doc is the operational room response curve. What you find many designers doing is tapering the HF response of their loudspeakers about a dB or two starting at 16kHz or so (varies with designer of course) and with the absorptive nature of room furnishings that can easily translate into the desired curve.