The Dude Posted November 27, 2013 Share Posted November 27, 2013 What are your ideas on the open baffle design, are there options. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted November 27, 2013 Author Share Posted November 27, 2013 What are your ideas on the open baffle design, are there options. I think keeping it simple might be best at this point. I'm planning on making the baffle about 36mm thick to ensure no resonance problems. Size about 30" wide and 10.5" tall, the height is restricted by the screen just behind the speaker. Using just the current baffle of about 10.5"x10.5" provided good results both in testing FR and just listening to center channel dialog. Music was also very good. So, none of the problems I encountered with the horn. As I said, the horn worked very well in lateral dispersion and with music. Sadly, vocals were very hit and miss and when it missed, it missed noticeably. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted November 28, 2013 Author Share Posted November 28, 2013 Making a baffle is quite a bit easier than a horn. Put this beauty together this afternoon. Currently drying the second coat of Polyurethane. Decided on the 30" width to match the bass baffle and as tall as possible within the constraints of the screen. I wanted to make it as solid as possible with some weight to minimize vibrations etc. Made an MDF and BB sandwich. 12mm BB on the outside and 3/4" MDF for the center. Turned out nice and solid and has some heft to it. Hopefully this little evolution will turn out better than the horn. This time it is less of an unknown since I already tried it with the smaller baffle that was part of the horn. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted November 28, 2013 Author Share Posted November 28, 2013 (edited) Another busy day, but got a lot done. I finished the open baffle and mounted the driver. I set it up and did some FR analysis. As you might guess, the bass response suffers a bit when running in an open baffle vs. having a horn or enclosure to load the driver. I found that it was just a little too anemic at at 204Hz XO. Since I have plenty of capability with the dual 15" drivers, I moved the XO to 296Hz, where the driver showed it could do well with little effort and did not need any EQ. After optimizing the phase alignment at the XO, I ran a few sweeps and am impressed they are that good in a room, modes and all. I am posting one sweep, no eq, no smoothing, no nothing. The second graph is the same as the first, but with a modified impulse window to remove a lot of the room interaction so I could better see the driver performance. Just for fun, threw in a couple of shots of the baffle front and back. Doesn't look as cool as the big horn, but I'm hoping it will sound better....at least without all the anomalies in dialog vocals. I plan on doing a listening session tomorrow morning and if it sounds promising, run Audyssey Pro again. Edited November 28, 2013 by Rudy81 Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted November 28, 2013 Author Share Posted November 28, 2013 It made a huge difference, for the better, to remove the horn and build an open baffle. Spent a couple of hours this morning listening to the new setup, without running Audyssey. Once again, used Top Gun, Gladiator, Joe Bonamassa, Cream, Boz Scaggs and a James Bond movie to evaluate. Vocal improvement was immediately obvious. No more honky voices in certain scenes. I was able to narrow down when the problem really showed up. Any scene where the actors are in an enclosed space, such as a hangar, bar, elevator, etc. caused a honky....but rather higher pitched voice than what I was expecting. Scenes in wide open spaces seem to sound normal with the horn. Music seemed unaffected as best I could tell and the same for sound effects. Very strange effect produced by the horn. The open baffle exhibited none of those problems, so I was pleased with that result. I was concerned last night when I first set it up that the open baffle's proximity to the screen and front wall would cause problems due to the speaker's back wave. Normally, it is suggested to keep any open baffle speaker at least 3 feet from a neighboring wall. Fortunately, in both FR testing and actual listening, I did not find any problems with frequency cancellation. This is my first truly open baffle HF setup. The Oris horns have an open back, but the designer's back chamber is in place, so there is some speaker loading to get the horn to 150Hz. I am stunned by how well this driver does with no enclosure. It sounds large and natural, perfect for a center channel! I like the sound so much that I'm wondering why I never tried a similar setup before. I guess I would always have wondered how a horn would sound in that location. These Tang Band 1808's are really awesome for open baffle use and that has been noted on many full range driver sites as well as open baffle discussions. I don't know how much better a set of Lowther's or AER drivers would sound, but for 5 to 10 times the price I can wait to find out. My thanks to the guys that sent me suggestions and ideas. The bottom line is that the horn just did not work for this application, and frankly I don't think it would work for any application due to the constricted vertical dimensions. I am confident the horn flare works because the Oris horns are fantastic. However, truncating the vertical portion of the horn as I did does not work and creates some really strange behavior. Now running Audyssey Pro so I can get a true sense of center channel performance with room compensation. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted November 28, 2013 Share Posted November 28, 2013 Man, you've been busy! Put your feet up and enjoy the day. Have a little turkey and a well deserved nap afterwards. Unfortunately the A.R. side of me know where you're coming from. If I build something that's not quite right, I obsess over it till it's fixed. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted November 28, 2013 Author Share Posted November 28, 2013 Man, you've been busy! Put your feet up and enjoy the day. Have a little turkey and a well deserved nap afterwards. Unfortunately the A.R. side of me know where you're coming from. If I build something that's not quite right, I obsess over it till it's fixed. All in good time. Today is an easy day for me. Wife is out of town and I'm going to a friend's for Thanksgiving dinner. Great day to work on this. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted November 28, 2013 Author Share Posted November 28, 2013 Success! Lot's of listening after Audyssey Pro got set and it sounds just fantastic. Best high's I've ever had from the center. Love the spacious 'feel' to the sound. No perceptible cancellation problems from the open baffle center. Clean, crisp dialog. When I started this project I had no clue I would end up here....but it is what it is. Once again learned a lot and will really have to delve into the open baffle theories. In the mean time, I'm going to sit back and enjoy. Happy Thanksgiving to all Klipsch fans and Klipsch staff! Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 20, 2013 Author Share Posted December 20, 2013 Had some free time recently and decided to remove the top of the horn I built to see if I could keep the LF performance and get rid of that nasty hump around 1.5kHz. No such luck. The horn flare seems to be producing the hump. I basically was using the horn sides as a wave guide and it still clearly shows the hump. The plain open baffle setup has a much flatter response and no problem in the 1.5khz area. It was an interesting project. For now, no center horn, just open baffle all the way. Quote Link to comment Share on other sites More sharing options...
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