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Open Baffle Epiphany!

dnewma04 said:
I like OB speakers. I have built a number of them. Some of my favorite all time speakers have been dipoles (Orions, my ML CLS converted to hybrids with AE woofers, DIY speakers using a BG RD 75 ribbon and 4 Dipole 15s per side.). I love the attributes that a good dipole offers, my next major speaker project will be a dipole system using dual 15 " woofers with an electrostatic panel. I keep sensing a great deal of offense on your part nearly every post I make in this thread. I don't understand what your motives are, but I'm trying to remain patient with you.

I don't know what you were getting at with the dnewma who comment, but if you were taking a shot at me, take it to PMs, please.



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I think you dissed Mr Pass in your comments.
 
OK, I'm gonna need to hear it before I break out the bib, but that looks like a single 12 or 15? Compared to a quad of 18s, I'm not going whet my appetite too much just yet.

How did it sound when you heard it? Could it blow the windows out of the room?

I didn't even know it had a woofer stashed in there, but I'm still leaning towards a few well placed 2245s not having much trouble besting it, bass-wise.
 
Poultrygeist said:
I think you dissed Mr Pass in your comments.
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I think Mr Pass is an outstanding guy with amazing skills with electronics. I haven't found any of his speakers to be particularly pleasing to me, however. I've heard literally dozens if DIY efforts that have exceeded any of his designs I've heard. If that's a diss, so be it.
 
Poultrygeist said:
Here's the backside. Go get the catsup.


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So, I'm assuming those do nothing below 40 Hz since, you know, you can't really hear anything down there that has any significant energy besides the rumble of earthquakes and thunder....and my gut tells me Mr. Pass likely isn't building those to parade in front of the HT crowd.
 
Surely your comment isn't pointed at me as I would hope you realize my statement suggesting that particular design from NP can't play below 40Hz was facetious. I'm fairly confident Mr. Pass knows content retrieval from that region is a worthwhile endeavor.
 
Quoted from your link, Paul...

20Hz - 40Hz = rumble
These are the kind of lows that are felt more than heard and add a certain rumble and sense of scale to movie soundtracks, pipe organ music and some electronic music. The sub 30Hz realm is very much sound effects territory - explosions, thunder, et al. There is very little content in music below 30Hz so club systems tend to cut off at this point if not a bit higher, whilst live music systems as seen at major festivals / stadiums tend to cut off at 35Hz (which makes the systems a bit more efficient so you need less gear to reach a given SPL than with a system with a 30Hz cut-off). A low tuned bass guitar does have output below 40Hz but it takes a seriously potent speaker system to reproduce that at high SPL. Sub 40Hz output adds a certain size and weight to music. It is almost more felt than heard and is rarely perceived independently of higher bass output (because any low frequencies will have higher overtones). A good word for it would be rumble. A bad word would be boom (boom happens much higher up).

So, I'm not sure I understand why you can't acknowledge that it's ok for someone to want their speakers/system to be capable of the above.

Scale, size and weight? Hell yeah, sign me up for some of that. :yes:

Help me out here, Paul. Am I missing something? :headscrat
 
What "I" said was there's little musical content in recorded music below 40hz. With the small group jazz I listen to it's higher. The rest are quotes from recording engineers and the like.

A sense of scale and bass weight are very important but far more common above 40hz ( where the notes are ).
 
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Poultrygeist said:
What "I" said was there's little musical content in recorded music below 40hz. With the small group jazz I listen to it's higher. The rest are quotes from recording engineers and the like.

A sense of scale and bass weight are very important but far more common above 40hz.
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There was a gentleman on AK a few years back that challenged the idea that there is a lack of sub 40hz bass in typical music. He used some software to measure many dozens of AK's favorite recordings and many recordings across various genres. An overwhelming majority of the music reached 30hz or below. If you dont care to reproduce that, I'm completely ok with it. However, there are approaches and equipment outside of the scope of your approach and I will not let you try to squash the other approaches.


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dnewma04 said:
There was a gentleman on AK a few years back that challenged the idea that there is a lack of sub 40hz bass in typical music. He used some software to measure many dozens of AK's favorite recordings and many recordings across various genres. An overwhelming majority of the music reached 30hz or below. If you dont care to reproduce that, I'm completely ok with it. However, there are approaches and equipment outside of the scope of your approach and I will not let you try to squash the other approaches.


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Then it should be relatively easy to find tons of sheet music with notes below 40hz. How bout some links?
 
Good Lord, Paul. You know it's out there. And it's not just melodic instrument reproduction that's of concern here. Percussion and effects certainly occur in this region and the artists put it into the recording for a reason and by God I want to hear all of it. Yes, it's infrequent and in the grand scheme of things rarely occurs, but it does occur. It may not occur in the type of music you favor, but that sure as hell doesn't mean it's not worth pursuing for those of us who have musical tastes that are more broad than yours and do listen to music that contains sub-40 Hz content. You can not care anything about reproducing sub-40 Hz content and that's fine by me and the rest of us. You can also be fine with Alpha 15'a takin' a **** when you ask them to bust 90db and that's well within your right, also. But some of us have come to the conclusion that as good as the Alpha 15a is (very good bang for the buck there, no doubt), its performance is limited and there are drivers out there that are more capable and able to fulfill our more demanding requirements....and that's fine as well.

- Michael
 
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Lots of music I listen to has sub 40hz content:) Whether or not you want to listen to the same music is another story:D

I have found for my own listening satisfaction I need something that will reproduce that end of the spectrum. I have built H-frame subs before and they do pretty well but don't cover the deep end and also don't have the impact of a sealed sub. All in my own opinion of course.

Having said that I do love the sound of open baffle speakers properly done. I am in the midst of building another set with Alpair 10As on top and the 15A on bottom. I can always use my sealed sub to fill out the low end.
 
In my original Lowther OB speaker system I used four of the modestly priced Eminence Alpha 15A woofers. I consider the Eminence Alpha 15A a great candidate for a dipole speaker system because of its 40 Hz fs, Qts of 1.3, efficiency of 92.5 dB/W/m, and affordable cost. In an infinite baffle this means that the SPL response is fairly flat as you descend from 100 Hz down to 40 Hz, there is a small pronounce hump at fs, and then the response drops at 12 dB/octave. This is not a great SPL curve for a boxed speaker since the bass time response will ring. But when you combine this driver with a 20 inch wide baffle's dipole response, which exhibits a 6 dB/octave low frequency roll-off, the resulting system SPL response looks really good for a bass system extending down to 40 Hz. For these types of designs, I like to use a 12 dB/octave low pass crossover between 100 and 200 Hz to further flatten the dipole bass response and smoothly transition to a full range driver. The Eminence Alpha 15A is a very flexible and affordable driver that works really well in almost any size OB, U frame, or H frame dipole speaker system.

- from MJK's webpage
 
Thats all great stuff and, again, I agree the Alpha 15a definitely has value in the OB universe.

Now quote MJK's experience with and opinion of the AE drivers that kicked the Alphas to the curb.

And please don't get me wrong...I'm not turning this into a pissing contest. I'm just making it clear to those who want more than the Alpha 15a can offer that there are options out that can offer a greater degree of performance.
 
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Thank the maker.

For those not compelled to read the link, the issues pointed out with the AEs were basically crossover difficulties that their lower sensitivity and lower fs and qts present. He goes on to say that active is the only reasonable method of crossing them over. He also calls them the best dipole drivers available, points out the superb craftsmanship and states that his lowther/AE combo will be his reference system for the foreseeable future.


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dnewma04 said:
Thank the maker.

For those not compelled to read the link, the issues pointed out with the AEs were basically crossover difficulties that their lower sensitivity and lower fs and qts present. He goes on to say that active is the only reasonable method of crossing them over. He also calls them the best dipole drivers available, points out the superb craftsmanship and states that his lowther/AE combo will be his reference system for the foreseeable future.


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Is it feasible for me to implement this design using my Alphas and AN full range drivers? I would assume so but I'm not sure. I like the lower profile and it seems the bass would be a big improvement over my flat baffle. Has anyone here built or heard this OB variation?

cubdog
 
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