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Open Baffle Epiphany!

With OB's, the "money" driver is the FR's not the woofers. It's the reason MJK used removable baffles to test 5 different full range drivers over his fixed woofers.

OB woofers exist to provide bass augmentation, because what you need and often get can be quite subtle. I expect that may be hard to grasp for those with a subwoofer orientation but no real experience with OB bass.

I've listened to my Beta12LTA's for hours without realizing the plate amps weren't turned on and no bass was coming from the H-frames. Sure I could hear the difference ( fullness/bass weight ) when I switched them on but a lot depends on the type of music that's playing. In my case it's usually small group jazz, a forte of OB's.

I recently discovered that one 100 watt plate amp ( Yung SD100 ) is all I need to drive 4 Alphas with the volume only one click above min. I usually can't see the Alpha's cone move and often touch them to feel their movement - subtle bass that does not draw attention to itself yet natural and alive.
 
I don't know, Paul. I suppose which driver is the "money" driver boils down to individual preferences and priorities. The last project I saw from MJK he was using AE LF drivers in a tandem configuration in H-frames (I think he was using Dipole 15's and actually, IIRC, they were more like U-frames)...so evidently he saw room for improvement wrt the level of performance offered by the Alpha 15's. With the AE's I believe he was getting a fairly flat response down into the mid twenties......which I don't think Alpha 15's in my H-frames ever got any deeper than the mid or upper thirties before a significant nose dive stymied their grunt. And I sure as hell couldn't get frisky with the volume if there was a healthy dose of hotly mixed first octave content in the recording. In most cases this wasn't an issue, but there were a number of times when I found myself frustrated upon reaching the limits of the Alpha 15's performance envelope (somewhere just south of 90 db)....enough times that I decided that particular design wouldn't satisfy me for the long haul. Now, I don't recall what kind of output levels MJK reached with his quad of AE LF drivers, but I'd be very surprised if they weren't perfectly capable of overloading the average sized domestic listening space before they reached their full potential. And even though sheer output capability is not a priority for me, I'm not likely to be content with a loudspeaker system (whatever the design concept may be) that has compromised LF performance. I want a solid LF foundation that doesn't stumble or omit in the first octave and can offer presence and girth at low output levels and composure and authority at higher levels and I've yet to hear a full range driver that is so sweet it removes that particular desire entirely. It's more than a desire, really....it's requisite for any DIY loudspeaker endeavor I'm interested in committing time and effort toward. And I like effortlessness. I like the sensation of hearing and feeling power and weight conveyed with a sense of grace and ease. It appears to me OB designs struggle with this more than anything else. If I can build something that overcomes this challenge I'll feel as if I've really accomplished something to be proud of....and, more importantly, enjoy the hell out of. And enjoy the hell out of for more than a few months as that's about as long as the 15a's in H-frames were able to keep my interest....and I'm not sure there's a single FR driver on this planet that could've changed that.
 
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tomlinmgt,

How often do you sit and listen to just woofers? How do they sound without your FR's drivers? We can get by in many designs with single FR drivers without woofers.

Adding "helper" woofers of the pro style variety to FR's in OB has just recently taken off in popularity. MJK was one of the first to pioneer this. Before, you would often see single driver antique Altecs in large flat baffles mounted close to the floor. Some purists still consider those superior to anything else.

"Down to the mid twenties?" There's little content in recorded music below 40hz. The lowest note on a double bass is E with a frequency of 41Hz and I can't remember the last time I heard low E.

MJK picked his "money driver" full rangers with the Lowthers before he went with AE's. Before the AE's he used double Alphas with the same Lowthers.

For anyone starting their first OB build the first and most important consideration should be the FR driver.
 
Poultrygeist said:
tomlinmgt,

How often do you sit and listen to just woofers? How do they sound without your FR's drivers? We can get by in many designs with single FR drivers without woofers.

Adding "helper" woofers of the pro style variety to FR's in OB has just recently taken off in popularity. MJK was one of the first to pioneer this. Before, you would often see single driver antique Altecs in large flat baffles mounted close to the floor. Some purists still consider those superior to anything else.

"Down to the mid twenties?" There's little content in recorded music below 40hz. The lowest note on a double bass is E with a frequency of 41Hz and I can't remember the last time I heard low E.

MJK picked his "money driver" full rangers with the Lowthers before he went with AE's. Before the AE's he used double Alphas with the same Lowthers.

For anyone starting their first OB build the first and most important consideration should be the FR driver.
Click to expand...

Two things. One, I'm past my first OB build and there are many others out there who are as well. If one has experienced what the Alpha 15a can do in OB and decides he wants more LF performance than that particular driver can deliver he's in luck....because it's out there. I want it, MJK wanted it, and I know many others who would want it, as well. Two, I suppose if I never listened to any music with instruments that can play lower than a double bass I'd be easier to please. But such is not the case....Low B on a 5 or 6 string bass is 31Hz. A0, B0, C1 and D1 on piano all reside below 40 Hz. No shortage of sub 40 Hz content in electronica and tribal percussion. Try out Micky Hart's "Temple Caves". There's a drum in there that's rumbling terra firma at 31 Hz and when it comes across strong and clear in the reproduction your friends will be impressed, women will fall at your feet and you will smile a ****-eatin' smile. A friend of mine came over and I let him pick some music to listen to. He wanted to hear Arcade Fire's "Reflektor". The song opens with a 30 Hz hit that's hot in the mix and my friend had only heard the song with his Maggie MG-IIIa's, Paradigm Studio 40's, and Spica Angelus (or his car stereo) and when he heard my distributed bass rig deliver that room rumbling intro with clarity and power (we weren't listening at loud volumes...maybe 80-85 db) he simply replied "goddamn". Which is pretty much the same response I hear from anyone who listenes to my Infinity QLS-1's playing Floyd's "Welcome to the Machine" when some of that sub-30Hz content comes out and compels all in the room to note the location of the nearest bathroom.

No, the really low stuff doesn't occur with any great deal of frequency and you may never hear any of it if you're only listening to a select few genres. But it is definitely out there and when you hear it done properly it's an experience that can leave an impression on the inexperienced and experienced alike which, to me, is the type of thing that makes the hobby fun. I could have someone who isn't really into high-end audio but has a deep appreciation for music (a bass player friend of mine comes to mind) come sit and listen to a really nice, high end FR driver playing solo and they'd likely say "that sounds really good". If I were to replace that FR driver with something a few notches down in performance (but still highly respectable in its own right) and supported it with a robust, clear and powerful LF foundation (which has a tendency to improve the presence of the mid range) the listener's response would be much more enthusiastic. I know this to be the case because I've seen it time and time again.

I won't argue the importance a good FR driver or mid range and HF driver combo, but I likewise won't concede that a good...no, make that extraordinary... LF foundation has no real merit in the world of OB (or the audio hobby in general, for that matter).
 
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I'm still looking for speakers able to reproduce the lowest note (18hz I think) in John Williams' "The Planet Krypton" which I once heard on this stupid loud car system.

Indeed, it left an impression on me. Favorable one, to be certain.
 
IME, once you get past the level of a Fostex/Tangband/Dayton/AN 150.00ish type driver on the FR, you are just swapping out sonic preferences rather than getting lower distortion, better frequency response, better dispersion, etc. I think most people are already picking mostly competent FRs to begin with outside of the BOFUs (?), and low end console type drivers. You'll have to pardon my dislike of Lowthers. I've never been a big fan of the sonic signature, the mid/high frequency response, or the flavor of "naturalness" that the fans subscribe to. I can understand why people do like them, it's just not a sound for me. So, with that said, seeking the typical FR nirvana level drivers like lowthers and above is not a goal of mine when I prefer the measured and subjective performance of much more affordable options.

I have a number of recordings where my alphas didn't keep up. In my system, the depth isn't much of a worry because of my distributed bass system. As far as full rangers go, there hasn't been one yet that I would have been content with without bass supplementation.

FWIW, my typical listening is acoustic singer/songwriter, classic jazz trios/quartets, indie, heavy metal/industrial, classical and some hiphop/rap thrown in the mix, roughly in that order.
 
"The lowest octave that can be heard ( 20hz to 40hz ) virtually has no energy in most music. The lowest note on a bass has a fundamental frequency of about 41hz. So this first octave contains such things as "room rumble" and the lowest notes of a pipe organ. The second octave ( 40hz to 80hz ) contains the fundamental frequencies of the low bass notes and the foot drum. So this is the first octave we are really concerned with unless we are reproducing earthquakes and the like."

- Bob Dennis ( Recording Engineer's Quarterly )
 
Poultrygeist said:
"picking mostly competent FR's to begin with outside of the BoFu"



Tell Nelson Pass his BoFu TL is incompetent :D



http://p10hifi.net/FAL/downloads/Pass-BOFU-TL-map-010910.pdf
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It makes the most of a driver whose performance I would deem unacceptable. Have you heard his BOFU TL? It's not particularly impressive but I've long contended Mr Pass should stick to electronics where he routinely builds stellar stuff. Speakers, not so much.


Sent from my iPhone using Tapatalk
 
tomlinmgt said:
I could have someone who isn't really into high-end audio but has a deep appreciation for music (a bass player friend of mine comes to mind) come sit and listen to a really nice, high end FR driver playing solo and they'd likely say "that sounds really good". If I were to replace that FR driver with something a few notches down in performance (but still highly respectable in its own right) and supported it with a robust, clear and powerful LF foundation (which has a tendency to improve the presence of the mid range) the listener's response would be much more enthusiastic. I know this to be the case because I've seen it time and time again.
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This right here is exactly right. I just received a pair of HA Augies to continue down the road of improved bass and head into OB again. I am currently running some car subs in a H frame. While they are not great by any means, like Micheal said the improve the presence of the mids. The whole sound of the Vals opens up more and becomes more lifelike. They are usually crossed at 45 hz and you can't really "hear" them. But they add so much to the whole presentation. I kicked them out to try a simpler setup a while back. Took only a few days to have them back in the rig.
 
Poultrygeist said:
"The lowest octave that can be heard ( 20hz to 40hz ) virtually has no energy in most music. The lowest note on a bass has a fundamental frequency of about 41hz. So this first octave contains such things as "room rumble" and the lowest notes of a pipe organ. The second octave ( 40hz to 80hz ) contains the fundamental frequencies of the low bass notes and the foot drum. So this is the first octave we are really concerned with unless we are reproducing earthquakes and the like."



- Bob Dennis ( Recording Engineer's Quarterly )
Click to expand...


It's clear you don't need or potentially even want very deep bass, but many do and consider it vital to providing a realistic musical experience. For those that consider it important, there are alternative drivers to the Alpha that provide superior performance and some people in this thread may be keen on achieving it.


Sent from my iPhone using Tapatalk
 
A friend just emailed that these OB's took first place in the unlimited class at P.E.'s annual speaker building competition. Mark Audio FR and Eminence woofer.


DSC_0573.JPG
 
Poultrygeist said:
"The lowest octave that can be heard ( 20hz to 40hz ) virtually has no energy in most music. The lowest note on a bass has a fundamental frequency of about 41hz. So this first octave contains such things as "room rumble" and the lowest notes of a pipe organ. The second octave ( 40hz to 80hz ) contains the fundamental frequencies of the low bass notes and the foot drum. So this is the first octave we are really concerned with unless we are reproducing earthquakes and the like."

- Bob Dennis ( Recording Engineer's Quarterly )
Click to expand...

That is honestly the first time I have ever heard that term used in my forty-three years on this planet. Is he a recording engineer or is he just affiliated with the quarterly trade publication? Doesn't matter....you can quote whoever you want, Paul. I have measurement equipment and use it regularly to learn where certain things are happening and I can guarn-damn-tee you Simon Phillips' bass drum(s) and gong bass drum (Terry Bozzio uses one as well) dip below 40 Hz and to say those instruments add virtually no energy to the music is, well, I guess ignorant is the best word I can come up with out of respect for Mr. Dennis. Good Lord.
 
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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Man, I haven't heard every speaker out there, but if the OB speaker that Mr. Pass is standing next to above can put out as much bass as a few well placed 2245s in 12ft^3 boxes, I'll put catsup on it and eat it with a nice chianti.
 
Jeffery said:
Man, I haven't heard every speaker out there, but if the OB speaker that Mr. Pass is standing next to above can put out as much bass as a few well placed 2245s in 12ft^3 boxes, I'll put catsup on it and eat it with a nice chianti.
Click to expand...

Here's the backside. Go get the catsup.


np_ob_back.jpg
 
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