Time coherence - how important and what speakers?


I have been reading alot about time coherence in speakers. I believe that the Vandersteens and Josephs are time coherent.

My questions are: Do think this is an important issue?
What speakers are time coherent?

Thanks.

Richard Bischoff
rbischoff
Well, Roy could use some dealers so we could hear before we buy. I don't understand the resistance in that area.
A couple of months ago I went to a local audiophile retailer to listen to Avalon Eidolon's. When I got there the owner said he didn't carry Avalon's anymore. I asked him why given the very upscale market this store was located in. He said he dropped the Avalon's because tastes have changed dramatically (the Bose affect) and the average consumer (regardless of income level) is just not educated enough to understand the differences in sound relative to price. In other words he just couldn't move a pair of $23K speakers, there just wasn't a big enough market.

Given the above, IMO retailers like Best Buys, Circuit City, Hi-Fi Buys and other mega stores are making it too easy to be a LAZY consumer. I think time is an important factor in this equation. We have tons of millionaires in the Atlanta area and I think it's difficult for many of them to spend the time to do the research necessary to investigate the broad range audiophile manufacturers and the art of sound reproduction. Because time is such an issue in their lives they either want to get a recommendation from a friend who has an audiophile system installed in their home or be able to drive 10 minutes to the local Hi-Fi mega store, walk into a sound room and listen to Joe Schmo sales guy give him the "we'll take care of everything" pitch. Secondly the consumer has been saturated by misinformation from Gigantore Audio Products Inc., making it more difficult for the small quality audio manufacturer to get his product out to the consumer. I'm SURE there are also many other factors in this equation as well. Audiokenesis and others may be able to shed some additional light on this subject.

This doesn't answer your question with respect to GMA, but I think it's an illustration of where many audiophile retailers are with respect to carrying certain high dollar products. They simply can't move certain products.
We have several dozen dealers- a list is available. Admittedly not a large number, but they do cover a fair portion of the US, some of Canada, and Puerto Rico. There are some international distributors too. Many have been with us for more than a decade. Most serve their local markets- they are not involved in the Stereophile/TAS product of the month club. Our few, select dealers that do significant internet business can be located easily.

If we seem to move too slowly... a long time ago we saw that if we grew too fast, quality and ergonomic issues would arise with the cast marble process- another reason to avoid the sales fluctuations created by magazine-based retailers. I can understand how all this gives the impression we're resistant to new dealers.

I think it's important for the health of our industry to patronize retailers who go out of their way to listen to everything, and avoid those who primarily sell whatever is new or hot. Our acoustic memories are short. So are our consumer memories- one can hardly count the number of audio maufacturers that no longer exist, once well-known. And many of them failed after a few years of marketing to only the big mail-order retailers, finding themselves dropped in favor of the new.

This of course, means that those products, and their designers never had much of a chance to evolve, so today we see a lot of "me-too" product- I think a result of slip-shod R&D efforts, even from quite large firms, because product is being rushed to the market- selling because it's new for this Fall, not because it's a significant improvement in the art.

I feel strongly that non-time coherent speaker design is one indicator of this lack of extended R&D effort in the speaker community. Another is the ignorance of what "radiation resistance" means. That is one of the most important parameters of speaker design that determines the sound you hear over at your chair.

Radiation resistance is determined by the quantity and the sizes of the drivers chosen and their crossover points. It is the term for the acoustic load on the driver, and is why a larger woofer has more "slam" than a smaller one which goes as low on steady test tones- the bigger woofer sees a higher radiation resistance down there.

That is just the LF range- the effect of varying or inadequate radiation resistance higher up the scale means that the tone balance and dynamic response change with listening distance. This is not my opinion, but a principle of operation firmly grounded in physics and explained in the peer-reviewed AES papers re-printed by Old Colony Sound Labs.

Best,
Roy Johnson
Green Mountain Audio