Speaker Design

[Steve Williamson]

OK, I was at the latest CEDIA exhibition on the Gold Coast, and Jamo was exibiting their latest R909 speakers, seeing as they are basically a front board with speakers screwed into their front openings, can anyone build this style of speaker without bothering with internal box dynamics. I.E. can you bolt a pair of drivers and a tweeter to an upright board and have it play the same.

Sorry to sound stupid but I have always bought speakers before.

[JCD]

The quick answer is no.. most drivers need to have an air cushion that a speaker box provides.
There are some drivers that can handle a boxless design -- e.g., IB subs basically have a box that is "infinite" in size.

My issue is that I don't understand how the back wave is handled. Speakers function by moving air. Usually you only hear the effect from the air being pushed by the front of the driver. I don't know how this design handles the air being pushed by the back of the driver. The tweeter is usually self contained, but those mid/woofers aren't.

I'm hoping that someone smarter will chip in -- I'm curious too.

JCD

[laserman]

Below are a couple of examples of speaker designers using the Open Baffle concept for the midrange and up area of a speaker. The end product is said to be a very open sound. I haven’t heard the GR ones yet, but the earlier NOLA speakers under the moniker of ALON did sound very open. To my ears they were very close to the sound one hears from electrostatic and other planar designed speakers but YMMV.

Read about them here:

http://www.gr-research.com/kits/ob-5.htm

http://www.gr-research.com/kits/ob-7.htm

http://www.nolaspeakers.com/

For NOLA Go to products -> open Open Baffle -> check out the Viper I & IIA speakers

[nm2285]

The Orion from Linkwitz labs uses that design too. There may be more info on the website about it, I didnt have the chance to look: http://www.linkwitzlab.com/orion_us.htm

[laserman]

Thanks nm for reminding me of the Orion speakers. I kept thinking I am forgetting a very well know speaker.

[Ayreonaut]

A few people have built full range IB speaker arrays too. Supposedly it can sound fantastic, since there's no box coloration at all.

[Brian Bunge]

These are technically known as dipole speakers. There are a few issues with such speakers. First, is the fact that there is no box to act as an air spring for the midbass/bass drivers so they will not have the same output capabilities as a "box" speaker and it will be much easier to bottom out the drivers due to this. Also, EQ needs to be used in order to boost the low end because the dipole effect causes the front and back wave of the drivers to cancel one another out, thereby causing response in the bass range to be extremely low. This is why you see many dipole speakers in a TM or MTM configuration sitting atop a sealed enclosure with bass drivers to pick up the low end or using multiple dipole subs to give the required bass response.

While I have not built dipole speakers yet, I know that things such as baffle width are important. Also, a dipole design requires 4x the Vd to equal the output capabilities of the same driver in a box. In other words, a dipole subs will need 4 12" drivers to equal the same output of the same single 12" driver in an enclosure.

[Steve Williamson]

I found this whilst trawling for DIY speaker designs, http://www.htguide.com/forum/showthread.php4?t=23598 looks interesting.

May just make me move into the garage for a few months

[F1 fan]

Steve Williamson wrote:

I found this whilst trawling for DIY speaker designs, http://www.htguide.com/forum/showthread.php4?t=23598 looks interesting.

May just make me move into the garage for a few months

I saw that one also,it sure does look interesting.

[scott]

check out bob in st.louis, he is using a free standing speaker set up.