DIY Open Baffle Info Needed

I like building HiFi speakers. Recently I became enthralled with the concept of open baffle. Where can I find concise information on what specifications I should be looking for with regards to a 10" or 12" full range or coaxial driver? Any recommendations for drivers around $150 each? Are there any online DIY plans or websites I should be looking at? Thanks in advance!
 

IG81

Member
2008-02-22 1:21 pm
You will find a lot of info by using the search function in this forum or Multi-Way.

My understanding is it boils down to this: the driver playing bass should be as large as allowable (high Sd), have a high Qts (>0.7 - opinions vary...) and substantial excursion capability (high Xmax). A single 10" or 12" certainly is possible, but you'll open-up choices if you go with a 15" or 18" bass driver and cross-over to pretty much any driver you like above this.

Here's something to start with:

http://www.quarter-wave.com/OBs/OB_Theory.html

I can't claim to keep up to date with OB design, but I think the above should still mostly stand.
 
Thank you so much...The little research I've done, I'm thinking a 10" full range or coax speaker to limit the baffle size and increase frontal dispersion and augment with one of my subwoofers (SVS or B&W). I recently bought KEF LS50 Metas and became a believer in Point Source technology. Eminence makes a series of speakers with screw in, coax mounted compression drivers. Much like Zu loudspeakers use. Would these be appropriate? Specs here... https://www.parts-express.com/Eminence-Beta-10CX-10-Coaxial-Driver-290-502 Or could I get away with some type of driver with a simple wizzer cone and DIY a coax mounted tweeter?
 

IG81

Member
2008-02-22 1:21 pm
If you plan to use box subwoofers, you open baffle's width will still have to be made wide enough to meet the highest frequency reproduced by the sub. While a bass-only OB woofer can have baffle extensions such as U or H frames to look slimmer, doing so with the mid/high driver risks introducing reflections and diffraction.

I have no experience with the Eminence coax, but they should likely be decent enough. I'd go for at least ASD1001, preferably PSD2002 for the highs, if not something from another brand entirely. Since this is the fullrange forum though, I will say that any good fullrange should do very well on OB if properly relieved of bass duty. Just avoid the super-low Qts units, below 0.35 or so, which might struggle to reach down to the sub even on a suitably large baffle.
 

Pano

Administrator
Paid Member
2004-10-07 6:05 am
Panama
I will say that any good fullrange should do very well on OB if properly relieved of bass duty.
I agree. I've used all sorts of fullrange drivers on OB (with 15" woofers underneath). I've used and heard many; from Vifa to TB to Wild Burro, Hem,p Saba greencone and even car speakers. All sound different but work well if high passed and supported with a woofer.
 
It is very easy to make open baffle speakers - too easy at first glance.

But it is very difficult to make GOOD open baffle speakers, that have controlled dispersion, smooth response and low distortion!

Some examples of both extremes and something in-between here https://www.diyaudio.com/community/threads/ultimate-open-baffle-gallery.123512/

Rbertalotto, please think more deeply about our goals - what size, what frequency range, what spl max, passive/active, analog/dsp etc.
 
I like building HiFi speakers. Recently I became enthralled with the concept of open baffle. Where can I find concise information on what specifications I should be looking for with regards to a 10" or 12" full range or coaxial driver? Any recommendations for drivers around $150 each? Are there any online DIY plans or websites I should be looking at? Thanks in advance!
Your inquiry about OB could have been written by me about five years ago. Not any more, though. Now, my main speakers are proper speakers - should say, "boxes". And, I plan to purchase bigger "boxes" as an upgrade.
But what about OB? - Well, guess that in the past fifteen or so years I smartened up, got more informed and better educated. That's all. I do not wish to bore you, but can share briefly some basic findings:
1. Best drivers (in terms of sound quality) are compression drivers.
2. Compression drivers are generally loaded into horns, and no further enclosure is not necessary because they are monopole. You do not need any OB if you were doing horns.
3. OB is the type of "mounting" (cannot call it "enclosure") suited exclusively for dynamic "dipole" drivers. Those also radiate backwards, so proper positioning OB is tricky. Also, for OB to be really effective, it's size has to be specific to the dynamic driver you are using.

Now, as a wise luminary I consulted years ago about this said to me- OB can get you about 75% towards "decent" sound, but no further. This is just the way it is. Most OB enthusiasts either fine with it or simply have not heard better because most of what is available in the marketplace now is outright crap. In comparison to most crap, OB will sound "open" and "unconstraigned", but at the price of certain "density", tonality, color. OB cannot really pressurize a room the way a box can.

The revered Nelson Pass did some OB's and you can find his technical drawings for those on-line if you Google. He also spoke at length about what what I mentioned earlier- that you cannot get proper base out of OB without soing something special. In fact Nelson Pass came up with "velocity loading" - you can find his "white paper" on the subject if you search. It is a "slot-type" of loading that is somewhat similar to what is used in some sub-woofers. But the crossover then gets all funky and defeats the purpose of the "simple" wide-bander approach.

So, I call it the three phases of DIY enthusiasts:- you are currently at the phase #1- because almost everyone starts with OB.

Some get stuck in that, those that are - smarter (pardon me), handier, and more determined, then move on to the various boxes. That's the second phase in DIY.
The more ambitious try fancy transmission line boxes, which could be allright, and will get you about 85% there.

It is premature to speak of third phase here. Anyways, best of luck!

PS. Through the years and through experience, I got simpler- so, I'll finish by offering you two simple advices:
- 1. A well done SIMPLE box will go much further along than any hirsute OB. Here's a youtube video of a well-done simple box optimized for a specific driver with fairly complex crossover (yes, it is a Tannoy, sold for about $30k /pair). (These are not my vids, they just show nicely what good boxes can do for ya) Have a listen:
And may be this too:
(BTW- the second video shows Tannoy Kensington which are about $15k/pair, with GR drivers (Gold Reference) are currently trading for $4k if you can find a pair as Tannoy does not sell and never sold GR drivers and crossovers for them, so those come from old pairs that were taken apart...)
- 2. Even an open-backed box is better than an OB, if you decide you really must go audio "commando" or prefer "hirsute" lifestyle. Those do have "volume" calculations to be done, though open air is included, and those calcs are easy to perform.

Cheers!
 
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In general, I tend to agree as it is great fun to make speakers, and having fun is probably the best excuse to dabble in this. On the other hand, you reap what you sow, and if what you sow is $100, guess it is also OK not to expect much in terms of "reaping"...
Nowadays I personally do not dabble in this as often and as much as I used to, got too little free time for that, but even when I did my simpler projects, I still tried to be as ambitious as I could when it came to both proper cabinetry and good drivers, and it justified itself as I was able to sell the fruits of my dabbling which enabled me then to get better drivers for my next project.
But if $100 is all you aspire for - well then, to each their own, and good luck to you! Cheers!
 
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Dave R

Member
2006-08-09 5:30 am
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Open baffles aren't for everyone. They can be polarizing and take awhile for one's ears to become conditioned to the new and different sound. I listen primarily to small group acoustic jazz and vocals at lower volumes and they perform brilliantly with that genre. Before I got started into DIY I owned a pair of Zu Omens. I thought they sounded great until I built these simple flat baffles with Betsy drivers over Eminence Alpha woofers. After one listen I sold the Zu's on Craig's List.

PB230008.jpeg
 
Open baffles aren't for everyone. They can be polarizing and take awhile for one's ears to become conditioned to the new and different sound. I listen primarily to small group acoustic jazz and vocals at lower volumes and they perform brilliantly with that genre. Before I got started into DIY I owned a pair of Zu Omens. I thought they sounded great until I built these simple flat baffles with Betsy drivers over Eminence Alpha woofers. After one listen I sold the Zu's on Craig's List.

View attachment 1016129
Your OB's look fine if a little narrow. The basics are obviously there - woofer is next to the floor for reinforcement, mid is off center, but still seemingly narrow as this is not a "folded" OB. In the same vein, I really liked Nelson Pass' OB - almost same except even much lowered, by turning woofer 90' into down-firing position, fully enclosed on all three sides and "velocity"-loaded through a slot through the baffle. That one apparently got a proper base through both slot-loading and further floor-boundary reinforcement. For the full range, he used obscenely expensive 8" CubeAudio Magus (https://www.cubeaudio.eu/cube-audio-f8-magus); in a similar build of my own (about five years ago) I successfully used Supravox (https://www.supravox.fr/en/produit/215-rtf-64-extended-bass-midrange-driver-25w-99db-8-ohms/), since I personally have an aversion to wheezer cones... It does need a tweeter - if funds allow, a lot of people use it with a bullet-type tweeter from fostex and alike.
Again, it seems most folks on this particular thread are on a tight budget, so these thoughts may not be applicable here.
 
Be careful when a forum participant postulates that "proper" bass is the kind that pressurizes a room - and everything else; upstairs, downstairs, outside. I'm sure you've heard the cars drive by with the bass penetrating your homes walls like they werent even there.

That type of bass isnt the only type enjoyable. I have to believe since it's the type most heard by anyone listening to reproduced music, that it is the defacto expectation sound, i.e. "proper". Particularly if you've something to sell - do it differently? Forget it...
 
Be careful when a forum participant postulates that "proper" bass is the kind that pressurizes a room - and everything else; upstairs, downstairs, outside. I'm sure you've heard the cars drive by with the bass penetrating your homes walls like they werent even there.

That type of bass isnt the only type enjoyable. I have to believe since it's the type most heard by anyone listening to reproduced music, that it is the defacto expectation sound, i.e. "proper". Particularly if you've something to sell - do it differently? Forget it...
I assume you were referred to one of my comments. Which is fine, all of us are entitled to our opinions which we enjoy sharing. Some like their porridge hot, some like it cold, some like it in the pot three days old...

Actually, the beauty of getting bass right is not in making your house into a neighborhood boombox. The cars with base rattling windows are annoying enough. But the fact is, most musical instruments have multiple harmonics present in their sound, which is why when someone is playing a live piano in a house, it is well heard by all of the neighbors - it naturally carries far. Most of the typical speakers cut a lot of frequencies present in "live" sound, truncating it into a wimpy semblance of self, neutering it of vitality, tonal color and rich harmonics.

I'd argue that good bass is essential for enjoyment of music - and I do not mean electronic drum machines. I mean real pianos, drums, cello and contrabasses to sound like real instruments.

With most OB using 12" & 15" woofers, the base might sound OK in the nearfield. But if you were planning to enjoy your music from across the room, well, tough luck!

However, when you get bass right, and I am not talking about subwoofers here, then, oh, the music, even jazz gets very satisfying, when the bass is well-integrated and as articulated as it should be.

Actually, I am a professional architect and the best analogy I can offer here is - a 'good' base to any genre music is like a foundation to a building: - It anchors and support the rest of the sound.
When the bass is obviously lacking, well, the overall sound is going to crumble down like a house of cards.
Cheers!