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Post by ocezam on Sept 14, 2014 9:17:28 GMT -5
In the last 5 or 6 years I've had a quite a few fine speakers come through my home. Magnepan, Bowers and Wilkins, Polk LSiM, Martin Logan, Vandersteen. I'm sure I've forgotten a few. Most I owned. Some I borrowed. Each pair I loved in one aspect or another. Some I loved for lots of reasons. However, all but one pair really never lasted in my home for very long. Disclaimer: The following are my opinions on what makes a good speaker. I do not intend to insult anyone. I owned my factory rebuilt Magnepan 1.6 pair for 2.5 years. I miss the soundstage so much. The warmth and imaging are to die for IMO. However, there are two aspects of Magnepans that will keep me from ever owning another set. First, I think they are too big. To me they look like a pair of upholstered bathroom doors standing in my living room. Second, they don't do bass well. I've always thought Jim Winey's (Magnepan Founder) big mistake was to stubbornly refuse to build hybrid speakers like Martin Logan. It would solve both of the problems I have with the brand. Indeed, for sometime I thought of owning some ML hybrids. So for the past few months, I've been planning a set of speakers around Bohlender Graebener's RD series of drivers. They are magnplaners. Same tech pioneered by Magnepan, but these are push pull with magnets on BOTH sides unlike Maggies only on the rear. This keeps better control on the diaphragm. I picked the RD50 for it's size. The drivers arrived yesterday and I duct taped them to a chair, and since I'm already actively bi-amping my B&Ws, I was able to remove the tweeter feed from them and temporarily hook up the B&G planers while still using the woofers from the B&Ws. The sound is incredible. I've got them crossed at 350hz. Even without a baffle, which will GREATLY enhance the transition between planer and woofer, the sound is amazing. Very Magnepan like. Warm, detailed, super wide soundstage. I'm so busy at work, I don't believe I'll get these done until the first of the year but I'm certainly looking forward to them. Here's a couple shots of the temporary setup as well as some pics of a 1/4 scale balsa model I built for the cabinets:      |
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Post by geebo on Sept 14, 2014 9:23:17 GMT -5
Those are gonna look great! Looking forward to seeing your progress.
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Post by novisnick on Sept 14, 2014 9:29:44 GMT -5
Very interesting indeed!! Can't wait to see, seem that they'll be a beautiful piece of art as well as functional masterpiece. Please keep us in the loop.
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Post by sct on Sept 14, 2014 9:36:24 GMT -5
I think you are gonna end up with some VERY fine speakers indeed! As long as you nail the transition from the mids/tweeters to the woofers you'll be in 7th Heaven. Good on ya!
One question, though: do you think it might be better to maintain a very slim, rectangular profile for the BG mounting panel rather than the triangle you currently have modeled? I would think that this would minimize any edge diffraction that the wider panel might induce. What are your thoughts?
SCT
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Post by ocezam on Sept 14, 2014 9:50:47 GMT -5
I think you are gonna end up with some VERY fine speakers indeed! As long as you nail the transition from the mids/tweeters to the woofers you'll be in 7th Heaven. Good on ya! One question, though: do you think it might be better to maintain a very slim, rectangular profile for the BG mounting panel rather than the triangle you currently have modeled? I would think that this would minimize any edge diffraction that the wider panel might induce. What are your thoughts? SCT Aesthetically, I wanted as narrow a baffle as possible, but a narrow baffle brings it's own set of problems. A sloped or angled baffle is recommended by B&G for purposes of transition to the cone sub. As most know, a dipolar speaker cancels frequency response at the edge of the baffle where the positive and negative waves meet. This is great for minimizing side wall reflections in Maggies, ML, and other dipoles. But this cancelation is worse at lower freqs and changes frequency depending on the width of the baffle. An angled baffle gives a smooth transition to the sub. I imagine that's why Apogee and Carver's Amazing speakers adopted a similar shape. It's also why Linkwitz's baffle on his LX-521 is shaped the way it is. I'm not concerned with edge diffraction. My model is similar to other DIY speakers with the B&G drivers. It's never been an issue, but baffles that are too narrow have been reported as causing problems with sub integration. As any speaker builder knows, ALL speaker designs are a series of compromises. Make your design decisions based around mitigating as many potential problems as possible, but no doubt the design WILL end up with minor flaws. NO speaker is perfect. I can't tell you how many different designs of this speaker have gone through my head, hundreds really. Three ways, four ways, different shaped baffles. Substituting a line array of B&G's Neo series of drivers instead of the RD series. Some designs used open baffle dipole mids and woofs ala Siegfried Linkwitz to transition to subwoofers. When a design came close to what I thought was ideal, I built a scale model in balsa. Each design was thrown out or changed after talking with other builders, as well as the fine folks at Parts Express, until I arrived at this design. I literally have hundreds of hours of design work and consultation on these speakers. I've built a half dozen or so models. No doubt many of the earlier designs would have produced a fine set of speakers. However, I believe this design represents a speaker that will do everything very well and nothing badly. We'll see.... |
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Post by ocezam on Sept 14, 2014 10:34:05 GMT -5
I'm currently listening to some fine jazz through my admittedly crude temporary setup. I can't think of ANY other driver(s) that you could take out of the box, tape to a chair, and have sound like these. Glorious!
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Post by AudioHTIT on Sept 14, 2014 10:55:57 GMT -5
Nice project ocezam, your cabinet work looks great and should make a nice line source. I hope your planning and hard work pays off, keep the pics coming as you make progress. |
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Post by bub on Sept 14, 2014 12:24:31 GMT -5
Great project. I would like to preorder for #0001 & #0002. . Keep the pics coming.
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Post by ocezam on Sept 14, 2014 17:14:33 GMT -5
Great project. I would like to preorder for #0001 & #0002. . Keep the pics coming. But... 0001 and 0002 are mine? |
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Post by Gary Cook on Sept 14, 2014 18:44:37 GMT -5
Interesting, I'm a big fan of DIY speakers. Any particular reason why you chose the RD50's in lieu of the RD28's? For mounting above the woofer, my preference would have been the shorter height. Power handling perhaps, but my mid/high frequency power amp choice would be the XPA-1L in Class A so 35 watts would be perfect for the RD28.
Cheers
Gary
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Post by bub on Sept 14, 2014 21:04:01 GMT -5
Great project. I would like to preorder for #0001 & #0002. . Keep the pics coming. But... 0001 and 0002 are mine? #0003 & #0004 will work. Have you decided on size of woofer yet ? |
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Post by ocezam on Sept 14, 2014 21:35:59 GMT -5
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Post by ocezam on Sept 15, 2014 7:36:27 GMT -5
Interesting, I'm a big fan of DIY speakers. Any particular reason why you chose the RD50's in lieu of the RD28's? For mounting above the woofer, my preference would have been the shorter height. Power handling perhaps, but my mid/high frequency power amp choice would be the XPA-1L in Class A so 35 watts would be perfect for the RD28. Cheers Gary B&G doesn't make the 28 anymore. Not sure why, or when they quit. They have the 40, 50, and 75. I wanted the extra power handling of the 50 vs. 40. I may trade my XPA-100's for a pair of 1L's, but either way they will drive the woofer only. I don't care about class A, but the 1L makes about 40% more power than the 100's (read the white paper). I keep telling myself to wait and get a pair of XPA-1's but the 1L's at $450 each are damn hard to pass up! The planers will be driven with my tubes. |
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Post by lionear on Sept 15, 2014 19:35:50 GMT -5
How about a few Genesis tweeters?
You might start with one, firing forwards. Then add more as well as some firing backward (out of phase with the ones firing forward). And then go with more..... and have something like the Genesis 300.
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DIY Teaser
Sept 16, 2014 10:47:55 GMT -5
via mobile
Post by bub on Sept 16, 2014 10:47:55 GMT -5
Great reviews. Perfect size. Looking forward to the build. |
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Post by ocezam on Sept 28, 2014 12:04:33 GMT -5
The sub cabinets are done...  
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Post by bub on Sept 28, 2014 13:22:54 GMT -5
I was wondering if it was going to be sealed or down firing port.( Like ML ) I personally like sealed. Moving right along. I do have a question and will pm. Looking good.
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Post by ocezam on Sept 28, 2014 14:23:37 GMT -5
I was wondering if it was going to be sealed or down firing port.( Like ML ) I personally like sealed. Moving right along. I do have a question and will pm. Looking good. To me, sealed just sounds better. Plus, ported ends up with too large a box in most instances IMHO. I got your PM. You need to share that story with the community here. Incredible! |
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reaper60
Sensei
Music Makes Me Happy!
Posts: 505
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Post by reaper60 on Sept 28, 2014 23:22:45 GMT -5
That sub driver you chose is excellent. I have one in my home theater with 2 matching 12" passive radiators tuned to 16 hz and it could crack a foundation with 200 watts.
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Post by ocezam on Nov 20, 2014 11:21:44 GMT -5
I've made a bit of progress. All of these pieces are just the rough cuts from the CNC machine:Here are the baffles. 1.25" MDF; Here are the drivers just laying in the baffles: Here the 1/2" Birch covers are laying over the drivers. These will have a nice finish and serve to hide the driver mounting hardware; Here are the rear support brackets;
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