"Good catch. I saw this last evening and wondered how long it would take for someone to notice it. According to Jeff, the graphs he supplied during the design process were based on anechoic measurements of the raw drivers and are not representative on the real-world response of the finshed speakers in the designed cabinets."
I'm not sure that's quite the explanation. Without an anechoic chamber, it isn't possible to capture anechoic measurements below about 200 Hz. The sample window is too short to get a good read on the wave lengths involved. My best guess is that Jeff took a nearfield measurement of the woofer and spliced it on to the rest of the driver measurements. But either way, the woofer measurement will not capture room gain, and the actual - 3db and 6db points will be lower than shown. And the region above 200 Hz is amazingly flat. Sure wish I could make it out to beautiful downtonw Livonia to hear these things.
Hello Dennis. The response Jim posted was kind of a conglomerate ;- ) The story goes like this. I built these speakers for myself using my own cabinet design (which was kinda ugly - I'm no Jim Salk). The orginal version used a JBL123A woofer. Unfortunately, the JBL was just not very sensitive, so I picked up a pair of Dayton 12's that ran around 92dB, and started over on the crossover design. I told Jim that getting the crossover balance to sound "right" between the open baffle midrange and the monopole woofer was the most difficult crossover I ever designed. In the end I found that shallower slopes worked the best and I ended up with a second order acoustic crossover for this crossover point. The midrange to tweeter did best with a more conventional LR4 since the tweeter already has a second order roll-off built in and PHL needs a little taming on the top end. When I got the speakers finished and had them voiced where I liked them I put them up against my main system. It's a four-way with a powered sub, dual Focal woofers, Focal midrange in a tapered TL, and a Seas Excel tweeter. After a few weeks my wife and son let me know that they still preferred the old Focal speakers, and since I agreed to keep only one set the new ones, named the Galileos, had to go.
At this time I working on the speaker that would become the Pharos and when Jim came down to visit he agreed to take the Galileos with him and see if he could sell them. Later he sent an email letting me know that he loved the midrange and high end on these speakers, he just didn't care for the bass very much. I had to agree that the Dayton woofer was a far cry from the PHL and MDT33 that they were mated with.
He brought up the Lambda. I found one listed that looked like it would work and John J. made a pair. Jim then sent one to me and I measured the response, impedance, and T/S parameters on it. Now here's where the measurements get funny. I didn't have the Galileos here, they were at Jim's, but I did have my original measurement files for the PHL and the Morel on the baffle and knew the offsets. I now had measurement files for the Lambda. The frd file was a combination of nearfield in a test box spliced to one meter data above 350hz. The Lambda, by the way, is flat to about 2.5khz and then drops off at about 4th order.
The response Jim posted is what I came up with on the computer using the new Lambda file and the original files for the PHL and Morel, knowing how I voiced that crossover point originally. That's why I asked Jim to bring them to the Indiana DIY gathering, because I believed they would sound good, but I had never heard them yet. Well, the moral to the story is - if you have done your measurements right, and know what you are doing, you can hit it very close this way, because these speakers sounded so nice I was flabbergasted. Several people told me they were best speakers they heard that day, and a couple guys said they were among the best they had ever heard. I was very happy with what I heard and Jim was all smiles watching me. Jim hit a home run on the styling too. I thought that they looked incredible. (I wished I could have stuck them in my Jeep and took them home, but this was not to be
We decided to not change anything in the crossover after the Indiana meeting. I really didn't think any tweaking was going to significantly improve the voicing and they sounded very coherent and smooth, and the balance seemed just right.
I wish you could hear them too. I think you would really like them.
Jeff B.
