Bookshelf dipole speakers - is it possible ?

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MisterTwister said:
why not? it may have same output as one woofer on H frame
Definitely wrong. See my link to Linkwitz above.

... but you are getting reduced harmonic distortion and it takes about the same space as H or U frame (even less)
Marginally.
... and you don't have to worry about resonances.
You don't have to worry about resonances in an equivalent H frame either.
 
"A single driver in an H-frame would have the same output if the distance D between the openings is 2d1"
well, I guess I got it all wrong :)

when drivers are attached back to back there is substantial decrease in harmonic distortion, at least based on my own measurements.

This arrangement may be even better (less space between drivers), see attached.

pacificblue, if you connect them with same polarity, you'll get no bass at all. they must fire in same direction
 

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MisterTwister said:
"A single driver in an H-frame would have the same output if the distance D between the openings is 2d1"
well, I guess I got it all wrong :)

Sorry for my wrong estimate,
looking at the picture you provided I was under the impression that D would be almost two times 2d1. I just had a look at some drivers of mine, where d1 in most cases is almost the same as the drivers depth. So D~2d1 seems to be realistic. :(
 
MisterTwister said:
pacificblue, if you connect them with same polarity, you'll get no bass at all. they must fire in same direction
Letting them fire in different directions should give a similar amount of bass as the front-to-front version with very little mounting distance, while reducing harmonic distortion further. Even more so in a front-to-back configuration that helps to cancel out speaker unlinearities and movements of the support construction.
 
It's been a while and since then I learned about smaller OB implementation like PMT1, Manzanita, Phoenix main panel. I've also gone from 6" woofer, 8", u-frame, h-frame, dual 8". But what I learnt was not to skimp on Bass (with capital) and use simple baffle.

This is the latest iteration. I managed to remove the mid and replace it with a FR. It does not have as sparkling high so I'm still working on that. I learnt also that phase or acoustics alignment is very important. Once the alignment is heard it's hard to "unlearn" the experience.

Image264.jpg


It's a 15" eminence but still looks reasonable on top of my desk and I can still do work/study. There are two variants of XO and compensation circuit. The first one is multi-staged and will produce 20Hz at -6dB but on some recording material would make the eminence bottom-out. So I opt for the less aggresive one.
 
if you happened to have a ton of power, I suppose you could do a ripole implementation of a high efficiency 12" woofer and then perch a 4" wide ranger in OB on top of it... still minimal depth, but probably greater low extension than a U of the same size, as fitting a very liberal definition of OB. Again, contingent on having an old beefy amp around.
 
Hi Mister Twister

I am more than curious as to your findings regarding the use of woofers in this fashion (SPL levels, equalization, etc). I bought myself fous units of an 18" PA woofer and any enclosure is to big for my small room. So now I am thinking about something along the lines of your idea/project for the bass. I will be using the threads/rods to hold two wooden beams in vertical position on which I will attach a MDF panel containing a B200 fullrange from Visaton. Something like the sketch (very flexible construction, BTW).

Erik
 

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Hi MisterTwister

I was already expecting that they would lose SPL too quickly, but as I will use them in a small room at relatively low sound levels I hope I can accomplish something nice. I hope their 18" size will help a bit as well...

Whenever I finish building them according to my sketch in the earlier post, I can always try to add some baffle (although I do not know exactly where...)

Erik
 
ErikdeBest said:
Hi Mister Twister

I am more than curious as to your findings regarding the use of woofers in this fashion (SPL levels, equalization, etc). I bought myself fous units of an 18" PA woofer and any enclosure is to big for my small room. So now I am thinking about something along the lines of your idea/project for the bass. I will be using the threads/rods to hold two wooden beams in vertical position on which I will attach a MDF panel containing a B200 fullrange from Visaton. Something like the sketch (very flexible construction, BTW).

Erik


Legacy Whisper did just that . Here's a clone project link http://www.htguide.com/forum/showthread.php4?t=3587&highlight=whisper
 
sideways ripole?

Given that the Ripole is the most compact OB, how about modifying as per sketch attached so it can be turned sideways on the desk...???
(I've got a couple of pairs of high Q 8"ers lying around, I might just try this)
 

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