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-   -   H frame/ Dipole/U frame ???????? (http://www.diyaudio.com/forums/multi-way/64588-h-frame-dipole-u-frame.html)

j.burtt 20th September 2005 02:58 AM

H frame/ Dipole/U frame ????????
 
I was a high end car audio installer years ago and we didn't have all these different bass cabinets, in the world I lived in. It was sealed or ported, and those were your choices. I listed my first post the other day and am educating myself before building a new speaker project. I keep seeing these different types of bass configurations and they catch my interest. Where can I go to find out more about them. I hate feeling ignorant when i am doing research on a project like this, especially when I am about to invest this much money and time.

Please give your recommendation enclosure designing programs.

Thanks, James

simon5 20th September 2005 03:21 AM

Two good free programs to design enclosures...

WinISD Pro
Unibox

All the enclosures you listed, U baffle, H baffle, etc are all in the dipole category. They will direct the sound differently. You can't design them using the above programs. I think there's a free program to design dipole but I don't remember what's the name of it.

This is one website where you can learn more about dipole :
http://www.linkwitzlab.com/

I'm sure users here will suggest many others.

If you're a bass head and you want tons of very low bass (~20 Hz) at very high SPL then dipole is probably not for you. If you want high SPL without too low bass or low bass without high SPL, then you should consider dipole. Most people who tried dipole over here say it's the best SQ they ever heard.

DIY_newbie 20th September 2005 03:27 AM

Re: H frame/ Dipole/U frame ????????
 
Quote:

Originally posted by j.burtt
I was a high end car audio installer years ago and we didn't have all these different bass cabinets, in the world I lived in. It was sealed or ported, and those were your choices. I listed my first post the other day and am educating myself before building a new speaker project. I keep seeing these different types of bass configurations and they catch my interest. Where can I go to find out more about them. I hate feeling ignorant when i am doing research on a project like this, especially when I am about to invest this much money and time.

Please give your recommendation enclosure designing programs.

Thanks, James

James,

Let me start with some basics.

Dipole is term for a speaker configuration in which the driver radiates from both the front and rear of the cone into the listening space. The driver is typically mounted into a baffle which seperates the front and rear wave so that they meet on the sides causing the system to radiate in figure 8 pattern.

H-frame and W-frame are terms used to describe a dipole configuration in which the frame has been "folded" to maximize the distance between the front and back of the driver while minimizing the volume required for the system. The trade off is that the H-frame and W-frame have "cavities" which resonate compared to a flat baffle.

The U-frame is esesntially a H-frame with the divider pushed forward so that it radiates in a cardiod fashion instead of figure 8.

Look at my thread here to see some completed H-frames :

http://www.diyaudio.com/forums/showt...threadid=64432

The reason people choose to implement dipole woofers is that we believe that it allows the system to recreate the music without being colored by the box the way it would in a vented/closed/bandpass box. However the dipole is not an efficient method of producing bass since you get cancelation when the front and rear wave meet at the side of the baffle.

As an example my H-frame which is 24" x 30", 18" begins to roll-off at 250Hz. In order to make up for this I added a 6db lp filter at 30Hz creating a flat response from 30-250hz at -12db from the reference in a sealed box.

Dipole woofers are still somewhat art as well as science for this reason there are alot of people with competing ideas on the best way to implement these sorts of systems. My personal preference is for large diameter, low excursion, high sensitivity, with lowish Fs. Also, plan on doubling up on your woofers to compensate for the LP fltering.

My frames used 2 x 12" woofers at 93db for a system sensitivity of 99db. IMHO Pro-type woofers with high sensitivity are the way to go for high output with lowest distortion..

YMMV

--Chris

AJinFLA 20th September 2005 03:36 AM

Hi James,

hopefully all the usual suspects will chime in here;) .
The Linkwitz site is the most comprehensive (by far) and is unique on the web.
Here are some others: U-frame http://www.geocities.com/kreskovs/John1.html
http://www.htguide.com/forum/showthr...highlight=arvo
FRD : http://www.pvconsultants.com/audio/boxmodel/uhframe.htm
And :
http://www.tolvan.com/edge/
cheers,

AJ

p.s. I'm an H man myself:D

http://www.openbafflespeakers.com/im..._orion_003.JPG

j.burtt 20th September 2005 10:11 AM

I downloaded Unibox and WinISD and some databases I think will be nice to have to evaluate several of the more common drivers used on this site and around the DIY community. My only question is what program opens the .ddb files I am finding the databases stored in ? I would really like to know since one has 410 and the other has 628 speakers stored in it.

Thanks,

James

Calvin 20th September 2005 11:06 AM

Hi,

look at these: http://www.audioelevation.de
A nice, very small and truly symmetrical concept (which SL´s sub-dipole´s are not).
The small chambers lead to a lower Fs than with any other design (5-10Hz is usual), so ultralow bass is possible. Drivers with Fs around 25-35Hz and progressive long-throw-suspensions are best. I prefer drivers with low to medium mass (within their size-class). A lot of Pro-drivers (15"-18") work very well, whereas a lot of HiFi-drivers fail.
They often claim longthrow-capabilities, but fail to reproduce ´silently´.
Peerless is one of the few companies that produce excellent dipole-drivers (and I´m not talking about the XLS! :whazzat: )
When You need high SPLs than stacking the subs is the solution.
Because a dipole can be built extremely small, You get nearly the same volume and SPL with 4-6 drivers in a dipole as with one driver in CB/BR but You still have the advantage of smallest group-delay and lower and more even excitation of roommodes and lower Fs.

jauu
Calvin

simon5 20th September 2005 05:13 PM

Quote:

Originally posted by j.burtt
I downloaded Unibox and WinISD and some databases I think will be nice to have to evaluate several of the more common drivers used on this site and around the DIY community. My only question is what program opens the .ddb files I am finding the databases stored in ? I would really like to know since one has 410 and the other has 628 speakers stored in it.

Thanks,

James

You open the Unibox spreadsheet, there's a "load" option on the spreadsheet and you load the .ddb file you want to use.

eros28 20th September 2005 07:18 PM

A bit Off Topic
 
Sorry for my ignorance but I'm new to DYI...

...I have a couple of questions regarding Dipoles...

1) Can you use dipole configurations as a center channel for a HT setup or is it strickly for two channel music?

2) In most dipole designs I've seen the use of 12" to 15" drivers...Is it possible to use a smaller driver (ie 8" - 10") for a smaller room?

3) I can imagine that the soundstage is large and deep BUT how is imaging on this type of speaker?

Thanks

Sorry hi-jacking this thread as I didn't see the need to start a new one.

DIY_newbie 20th September 2005 08:11 PM

Re: A bit Off Topic
 
Quote:

Originally posted by eros28
Sorry for my ignorance but I'm new to DYI...

No problem, thats why we're here ;)

Quote:

Originally posted by eros28
...I have a couple of questions regarding Dipoles...

1) Can you use dipole configurations as a center channel for a HT setup or is it strickly for two channel music?
[/B]
There is nothing restricting dipole use as a center channel. However, t would be difficult to mount a large baffled speaker on a TV so you probably would get pretty early roll-off

Quote:

Originally posted by eros28
2) In most dipole designs I've seen the use of 12" to 15" drivers...Is it possible to use a smaller driver (ie 8" - 10") for a smaller room?
[/B]
The reason for using large diameter drivers is to make up for the baffle roll-off without needing insane amounts of xmax. You could theoretically get away with smaller drivers assuming you didn't need alot of low end extension. Also IMHO smaller bass drivers never realistically reproduce the really big instruments hence my preference for 12"+ bass drivers. Its just hard to believe a pipe-organ being generated by 6.5-8" woofers.

Quote:

Originally posted by eros28
3) I can imagine that the soundstage is large and deep BUT how is imaging on this type of speaker?

Thanks

Sorry hi-jacking this thread as I didn't see the need to start a new one. [/B]
Also IMHO, dipoles are very transparent with a wide and deep soundstage. Imaging is not as "razor-sharp" as the current generation of very narrow baffle speakers. I think this is a benefit not really a drawback, if you listen to live music how often do instruments radiate as point sources? Take a guitar for example, you have sound being created by the fingers moving on the strings, the strings themselves, as well as the body of the instrument..

As usual YMMV,

--Chris

mefistofelez 21st September 2005 03:40 AM

Dear AJinFLA,

can you let me know what brand/type are the drivers in your dipole?

Thank you,

M


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