The Advantages of Floor Coupled Up-Firing Speakers - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th April 2008, 03:23 PM   #1
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Default The Advantages of Floor Coupled Up-Firing Speakers

Note: Thread title changed.

Reading what many people in audio wrote on the subject of loudspeaker design (Carlsson, Beveridge, Moulton and Linkwitz were my main inspirations) I came to the conclusion that the real issue is that loudspeakers and room form one system.

Recently I had an impression that this I also a view of gedlee (Dr Earl Geddes) when he wrote that the most important parts of his book are those concerning waveguides and room acoustics ("Don't read the stuff on non-linearity, but fully grasp the chapter on waveguides. Thats what I would say today.That and room acoustic")

Later I came to believe that what Dr Geddes writes on the topic of room reflections is in the end of the day the same thing that Carlsson, Beveridge or Moulton and also Linkwitz have written on the subject. And that in their designs they wanted to achieve the same end - to eliminate the detrimental effect of room reflections.
And yet their designs are so much different!
Apparently there are many ways to achieve the same. Linkwitz’s experience with subjective evaluation of his own an yet very different dipole and omni designs confirmed this for me.

I have very unusual loudspeakers which I have built some time ago with those room-speaker interface things in mind. These are very short omnidirectional loudspeakers. They are just 20 cm high and have 8 inches wide range driver on top and firing upwards.
The loudspeakers are to work on the floor – the driver is only 20 cm above the floor – and against the wall.

In this positioning they happen to be quite similar to the late Stig Carlsson designs (carlssonplanet.com, but the Carlssons are two-way and much more complicated because of that) but were not inspired by them.
I didn’t know the Carlssons when I was building these and my first and main aim was to eliminate the detrimental effect of early floor and ceiling reflections without resorting to unavailable true linesource (like Beveridge)
The second aim was to build loudspeaker least visually obtrusive, loudspeaker that would be practically invisible in the listening room (which in may case at the time was also a living room). Perhaps it was even equally important goal.

But frankly speaking I wasn’t thinking a lot and I think now that I really didn’t know what I was doing and still I don’t – I have no technical background – and it was and it is all mostly intuitive.

But the outcome appeared to be quite satisfying. This is still work in progress. Achilles heel of the loudspeakers are 8 inches Fostex wide range drivers which have major resonant problems in the break-up area. Out of the box they were literally howling at me. After some driver-mutilating (i.e. tweaking) I can say that these problems are only partially solved for the time being and I am looking for a different driver

Soon I will have a new listening room that is 350 cm wide and 550 cm long. Not too big and not the best proportions but I can arrange it specifically for audio purposes.
I am considering positioning the speakers against the opposite longer walls (scheme attached). Stereo basis would be 330 cm. The listener is to be located 200 cm from stereo basis, 250 cm from both speakers

All this with the questions of minimizing early reflections in mind and particularly with what Dr. Geddes has written on this forum.

A big thanks goes to Dr Geddes!

To my not very big surprise the resulting set up happens to be very much like Beveridge positioning of his line source electrostatics.

The positioning would give very early reflections (VER) <1 ms from adjacent wall. I hope that they would not be strong enough to become audible problem because the Fostex is quite beaming (I don’t know for sure but 8-inchers are typically 7-8 dB down at 1 kHz at 75-90 degrees and 12-15 dB down at 2 kHz). I am also considering using small Carlsson style absorbers effective for midrange and high frequencies as an option.
Apart from those very early (and hopefully low in level) VER I expect that:
- significant reflections off the adjacent wall would not reach the listener
- floor reflection would not reach the listener
- first reflections off the front wall and off the back wall would reach the listener 9.3 ms after the first wavefront
- first reflections off opposite walls would reach the listener 8.3 ms after the first wavefront
- first reflections off the ceiling would reach the listener 8.8 ms after the first wavefront (ear at height of 90 cm, ceiling at height of 300 cm)
It seems that apart from those earliest reflections <1 ms all other reflections are delayed more than 8 ms and caught by proximity (Hass) effect.
And all this in a relatively small listening room. The bigger the better.
Also I am considering using some wide band absorbers to reduce the reverb after first 50 ms as Moulton recommends.

What do You think? Any suggestions? Ideas? Your own unusual setups?

best,
graaf
Attached Images
File Type: jpg room.jpg (10.3 KB, 9599 views)
__________________
"high phooey and hystereo" - Yascha Heifetz
  Reply With Quote
Old 15th April 2008, 06:20 PM   #2
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Default re: The Advantages of Floor Coupled Up-Firing Speakers

Quote:
Originally posted by graaf
proximity (Hass) effect.

a mistake
of course that Haas effect is called "precedence effect" not "proximity"
__________________
"high phooey and hystereo" - Yascha Heifetz
  Reply With Quote
Old 15th April 2008, 09:07 PM   #3
49 - for the 18th time
diyAudio Member
 
c2cthomas's Avatar
 
Join Date: Oct 2006
Location: Near "Music City" (Nashville Tennessee)
graff - I like where you are going with your ideas... I'm working along similar lines of thinking but was not aware of the carlsson site until you listed it and found it very interesting. I made a couple of prototype omni speakers along the lines of Walsh 5 (Walsh 5 remake thread) and enjoy them very much - but improvements can be made I'm sure. I decided that before I spent piles of time, money and effort that I would read up about things, and like you have discovered that about half (debatable) of the challenge of good sound reproduction is the room itself. Reading Dr. Geddes book on audio transducers now. So I'm interested in this topic and I'm sure that others will join in. BTW do you have any photo's of your speakers?
__________________
DIY audio can be expensive – but getting to see things go up in smoke - that's priceless!!!! ..... "whatever - call it brainfart of Mighty ZM"
  Reply With Quote
Old 15th April 2008, 10:54 PM   #4
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Quote:
Originally posted by c2cthomas
graff - I like where you are going with your ideas... I'm working along similar lines of thinking but was not aware of the carlsson site until you listed it and found it very interesting.

I'm glad to hear that

this "white paper" is particularly intersting: http://www.carlssonplanet.com/downlo...sson_ortho.pdf

Quote:
Originally posted by c2cthomas


So I'm interested in this topic and I'm sure that others will join in.
I hope so

Quote:
Originally posted by c2cthomas

BTW do you have any photo's of your speakers?
I have photos of the "almost finished" cabinets (WxDxH - 33x33x16 cm), the driver is highly modified Fostex FE206e

best,
graaf
Attached Images
File Type: jpg p6255901.jpg (60.9 KB, 9180 views)
__________________
"high phooey and hystereo" - Yascha Heifetz
  Reply With Quote
Old 15th April 2008, 11:30 PM   #5
49 - for the 18th time
diyAudio Member
 
c2cthomas's Avatar
 
Join Date: Oct 2006
Location: Near "Music City" (Nashville Tennessee)
Oskar Heil Speakers uses speakers that fire up towards the ceiling and an Air Motion Transformer for the HF. http://www.unitedhomeproducts.com/id101.htm

In my Walsh 5 remake I am using the AMT above 5 KHz and an upside down 10 inch Pioneer for mids and LF up to 6 KHz. Below is a sketch of what the final version should look like - if I ever get around to making that version of the speaker. At present I'm considering other adventures which include OB.
Attached Images
File Type: jpg speaker box for heil tweeter n walsh driver 03.jpg (17.1 KB, 8813 views)
__________________
DIY audio can be expensive – but getting to see things go up in smoke - that's priceless!!!! ..... "whatever - call it brainfart of Mighty ZM"
  Reply With Quote
Old 16th April 2008, 09:08 AM   #6
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Quote:
Originally posted by c2cthomas
Oskar Heil Speakers uses speakers that fire up towards the ceiling and an Air Motion Transformer for the HF. http://www.unitedhomeproducts.com/id101.htm

In my Walsh 5 remake I am using the AMT above 5 KHz and an upside down 10 inch Pioneer for mids and LF up to 6 KHz. Below is a sketch of what the final version should look like - if I ever get around to making that version of the speaker. At present I'm considering other adventures which include OB.
Heil speakers are interesting in combining dipole and omni radiation pattern
But In my loudspeakers I don't want separate tweeters. I "believe" in crossoverless designs.
Fortunately the Fostexes I use in my configuration (they are currently positioned against the same reflective 5.5 m long wall) give me almost all treble I subjectively need. And that with the whizzers cut off. With the whizzers they were excessively bright for me. Now they are even more beaming but I get the trebles from the wall and ceiling reflections. When positioned appr. 20 cm above the floor the Fostexes though beaming nevertheless "illuminate" the ceiling and larger parts of room walls with the trebles quite uniformly. This is a kind of additional advantage of such a low positioning just above the floor.

So I am rahter thinking of adding separate stereo subwoofers behind the main loudspeakers than of adding any kind of tweeters or midtweeters

best,
graaf
__________________
"high phooey and hystereo" - Yascha Heifetz
  Reply With Quote
Old 16th April 2008, 02:59 PM   #7
diyAudio Member
 
thinkbad's Avatar
 
Join Date: Sep 2004
Location: in the middle of nowhere
graaf

Very interesting topic !

I work with some of the ideas you come up with and I`m well aware of Stig Carlsson`s loudspeakers.

My current speaker setup is a pair of Jordan jx92 in 12L in closed "boxes" close to the floor and 1,4 m away from the nearest wall.
I even tried to put the two together to form a sphere and place it in the corner as a "stereo-speaker" with a sound barrier in between and listened in nearfield, sort of ambisonic approach.
  Reply With Quote
Old 16th April 2008, 03:09 PM   #8
diyAudio Member
 
thinkbad's Avatar
 
Join Date: Sep 2004
Location: in the middle of nowhere
IKEA bowl in stainless for high WAF-factor
Attached Images
File Type: jpg sfere.jpg (84.0 KB, 8996 views)
  Reply With Quote
Old 16th April 2008, 06:52 PM   #9
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
wow! stainless bowl!
great idea!


Quote:
Originally posted by thinkbad


Very interesting topic !

I would say that it is getting even more and MORE interesting

Quote:
Originally posted by thinkbad

I work with some of the ideas you come up with and I`m well aware of Stig Carlsson`s loudspeakers.

My current speaker setup is a pair of Jordan jx92 in 12L in closed "boxes" close to the floor and 1,4 m away from the nearest wall.
The Jordans were my second choice. I admire what Ted Jordan does. I am a real "Jordan propagandist" in audiophile web community here in Poland
I chose the Fostexes because as 8-inchers they are more directional (I needed high directivity in this design), they require less excursion for a given SPL which is a good thing and having very low Qts they need smaller box which is a very good thing.

Quote:
Originally posted by thinkbad

I even tried to put the two together to form a sphere and place it in the corner as a "stereo-speaker" with a sound barrier in between and listened in nearfield, sort of ambisonic approach.
WOW!
I didn't know that anybody has tried this approach apart from myself!

You mean AMBIOPHONICS? (www.ambiophonics.org)
I was inspired by ambiophonics when I tried something like this. I built rectangular box 23x23x23 cm with wide rangers of the size of JX92s on opposite sides.
What I was trying to achieve was an "ambiopole" i.e. "crosstalk-cancelled stereo array" without physical barrier or electronic cross-talk cancellation, which are normally required (alternatively).
I was relying just on the directivity of the drivers and of the cabinet.

And it worked! I positioned them diagonally close to the corner and into the room and also against the wall and in the middle of the room. And they worked in every position. It was amazing. This was the moment I finally departed from "standard stereo triangle" set up for good. In terms of recreation of natural space "standard stereo triangle" was pathetic in comparison. Unfortunately the thing didn't work well with some recordings and I finally postponed the project.
Later I came across another less known website: http://www.stereolith.ch/
Walter Schupbach has been making similar speakers for twenty years now or even more!
His latest designs employ monophonic tweeters. Stereo signal goes only to the sides.
Joseph Manger has discussed that type of stereo loudspeaker in his "Manger Discus" patent. He called it "dummy head stereo" and raised some doubts as to the compatibility of this design with currently made recordings. From my experience I can confirm that those problems exist. Alas! Because with suitable recording one can get real 3D from such speakers! I mean REAL 3D. The listening room literally disappears. "Walls, ceiling and floor disappear and the air itself is playing music!" as one of may audiophile friends has decribed this experience. "Standard stereo" is laughable in comparison.

Here is a review of somewhat modified Schupbach loudspeakers:
http://www.magazine-audio.com/essais...-par-richard-d

best,
graaf
__________________
"high phooey and hystereo" - Yascha Heifetz
  Reply With Quote
Old 16th April 2008, 08:20 PM   #10
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Quote:
Originally posted by graaf
"Standard stereo" is laughable in comparison.

or shall I better say "lamentable"?

Quote:
Originally posted by graaf


Here is a review of somewhat modified Schupbach loudspeakers:
http://www.magazine-audio.com/essais...-par-richard-d

let me draw Your attention to two points in the conclusions of this review. The reviewer writes:
"Profondeur et hauteur d’image musicale hors du commun" i.e. "extraordinary depth and height of soundstage" and at the same time:
"Image stéréo étroite" i.e. "width of the soundstage is shortened"

this conclusions are highly symptomatic of the main problem of this design

the problem with this "dummy head stereo" or „pseudo-ambiopole”, as I like to call it, is that it reproduces EXACTLy what is in the recording
It means that "it produces no artificial soundstage"

on the other hand many or even most of contemporary recordings are made with an assumption that they will be reproduced in a standard stereo triangle and thus they rely on the loudspeaker spread in such a triangle to produce the width of the soundstage
such a soundstage created by loudspeaker spread in a stereo triangle is of course completely artificial because it has nothing to do with natural spatial cues for distance perception

pseudo-ambiopole is reproducing as faithfully and as accurately as possible all the spatial cues encoded in the recording ("natural" or "artificial")
but many recordings give little or no spatial cues for soundstage width because the width "is to be created by" "spreading of the loudspeakers in a typical stereo triangle"

when there is little spatial cues for soundstage width in the recording pseudo-ambiopole produces "shortened soundstage width" as described by that French speaking reviewer: "Image stéréo étroite"
and when there is NO spatial cues for soundstage width in the recording pseudo-ambiopole produces literally NO SOUNDSTAGE WIDTH, the soundstage collapses completely
and this is quite catastrophic and a fatal flaw of this design from practical point of view

BUT precisely speaking the device is right, only recordings are crappy

but what can we do?

fortunately - yes we can do something

we can try a different method of "acoustically hiding speakers in the room"
yes, this is EXACTLY what pseudo-ambiopole does – because of its "bipolar" directivity our hearing is unable to locate the speakers as a distinct sources of sound – they are hidden, they disappear, "the air is playing music"
this is the secret - the ESSENCE of this design

I realized that Harold Beveridge proposed such a different solution – an alternative method of achieving the same result

in his recommended speaker positioning (low directivity speakers against the opposite side walls facing each other I front of the listener) the speakers are acoustically integrated with the side walls – they are perceived as a reflection off the wall

in fact for our hearing the speakers ARE reflection off the side wall and for our brain the room itself is playing the music and not the speakers

this is the solution I decided to try in my new listening room
My latest loudspeakers (image of the "almost finished" cabinet attached above) I built with intention to emulate as possible the room-speaker interface possible with true line source used by Beveridge with regard to effective elimination of distracting early floor and ceiling reflections.

best,
graaf
__________________
"high phooey and hystereo" - Yascha Heifetz
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Using a diffuser cone for up-firing speakers tspringer99 Multi-Way 19 23rd July 2014 02:04 AM
Floor Standing Speakers. gurpreetsingh Full Range 11 12th June 2012 06:42 AM
side/ rear firing speakers Good/Bad? mcmahon48 Multi-Way 1 6th February 2009 12:28 PM
How far can the driver of a down-firing sub be from the floor? The Paulinator Subwoofers 11 16th May 2007 08:10 PM
Woofer: side firing pair vs front firing? tcpip Multi-Way 13 9th September 2005 02:13 PM


New To Site? Need Help?

All times are GMT. The time now is 04:15 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2