Open baffle -- some questions

[jmar]

I'm really curious about this for a lot of reasons.

I've seen a number of "audiophile" (hate that word) manufacturers that even have some commercial products.

** do driver manufacturers actually recommend specific drivers for open baffle use? (fostex etc?)

** just to (possibly) build something eventually, can anyone recommend a project that is the best bang for the buck? (or a driver)

I saw a "Tekton design" system that uses an attached subwoofer that looks interesting.

I like low listening levels, which I know is important -- and classical music as well.

[chris661]

Seeing as you hate "that word", you'll like this
Lenard Audio Institute - Education - Greetings and introduction.
at the bottom.

Generally speaking, a driver with Qts above 1 will be good for OB use. You can use lower, but this affects bass response.
Wild Burro Audio Labs - DIY Full Range Speakers
Might be worth a look for some drivers...

[jmar]

Nice links.

Thanks.

[Rudolf]

Originally Posted by jmar

** do driver manufacturers actually recommend specific drivers for open baffle use? (fostex etc?)

I know of VERY few manufacturers who offer specific 'dipole' woofers. aespeakers comes to mind. Some ribbons can be used as dipole drivers. AFAIK Fostex does no specific OB driver. In fact most Fostex drivers urgently need woofer support to work in an OB.

** just to (possibly) build something eventually, can anyone recommend a project that is the best bang for the buck? (or a driver)

This will very much depend on your musical taste. A 'girl with guitar' OB will cost a lot less than an OB capable of AC/DC.

I saw a "Tekton design" system that uses an attached subwoofer that looks interesting.

Very small OBs are always suspicious.

I like low listening levels, which I know is important -- and classical music as well.

One of those 8'' (or bigger) wide range drivers could do. Wild Burros Betsy or Ciare CH250 perhaps. For some more dollars you get the Visaton B200, Audio Nirvana Super 8/10 or Hemp FR8.

[ashok]

Uses drivers with a Qts of close to 0.7 to 1.0 to help improve the bass response. But that's only at the low end.
You could use a boxed sub for the low end ( below 90 Hz ?). This however will change the 'low end sound'. It will not be exactly the same as a full range OB with say two 15 inchers for the low end. But you can get away with less power requirement at the LF end and a smaller box and a smaller OB baffle dimension.It will still sound good... better than a boxed speaker.

If you search you will find other threads on this and find out that many have reported that using a flange at the ends of a baffle will ( might ? ) affect the imaging and spacious sound that a plain flat baffle can produce.

Only way to find out is to try it yourself !

I've used 12 inch drivers with a Q of just about 0.6 and they sounded great. It still needed a boxed sub to match traditional boxed speakers in the low end. I can't use two 15 inchers per side ! However even without the sub it sounded very good with most music. The OB low end was equalised with a 6dB / octave filter.

Cheers.

PS. A complete answer to your question would be too long to post. It's already been covered in several threads on OB speakers. Spend some time and read them. No single post will be a complete answer but you WILL get to learn a LOT by reading them all! See what others have tried and how it turned out. You have to spend time searching out the information.......there is no easy way out !

[Jim Shearer]

You might want to check out MJK's quarter-wave.com site. Martin has done extensive work on OBs. I have built his low-end OB using a Fostex FF85k and an Eminence Alpha 15a which uses a passive XO. My results are on the big thread on that OB. My results can be summed up in one word: WOW. If you like the dipole/bipole type sound, then this may be a good project for you.

Cheers, Jim

[just a guy]

Originally Posted by jmar

I'm really curious about this for a lot of reasons.

** just to (possibly) build something eventually, can anyone recommend a project that is the best bang for the buck? (or a driver)

If you just want a quick experiment that costs almost nothing just to see if you like OB you could do something like this project my buddy did.

The Smallest OB (amateur audio)

It only goes down to 150 hz and you need a high q driver but it works great, sounds great, and it doesn't get any easier than this. It's a low quality driver and it's a coax (not fullrange) but you can use your choice of high q (over 1 qts) driver. Just make sure to model it first.

[rjbond3rd]

I agree on the Betsy's ($100), the Visaton B200's (about $300 but hard to find lately), and the MJK stuff (hoping to build his Goldwood/Jordan JX92S with passive xover next).

My word of advice: if you're doing a single driver on OB, swap out as many amps as you can because the difference in bass results is huge. I found that an SS amp had tremendously more (and tighter) bass than my two small tube amps, but the SS lacked the midrange magic. I'm trying two more tube amps in the coming weeks in an attempt to get strong bass /and/ the midrange magic (the Miniwatt and a 35-watt Bada hybrid).

[serenechaos]

Originally Posted by rjbond3rd

... swap out as many amps as you can because the difference in bass results is huge...

like, as in, ck output impedance, and feedback, and how they relate to damping?
it makes even more difference when a driver is used in a speaker without much load on the cone?

In other words, a high feedback, low output impedance, SS amp might help compensate, and be needed to bring the bass up?
Better than acoustic loading?

[human.bin]

if you like classical, you'll be amazed at how closer you can get to feeling a piano with OB speakers... on the other hand a single driver will struggle with big orchestral pieces, going with an helper woofer will really free them up...

i think that betsy+boomer (you can find it on this forum) is well worth a look given you are in the usa, you can always start just with the betsy and then consider to upgrade