The Advantages of Floor Coupled Up-Firing Speakers

Yeah yeah you can quit the guessing anytime. Your speakers are most likely not tightly matched. You ever try to null cancel test them?

I consider my Nathans "tightly matched". I would even go so far to claim they are tighter matched than the majority of speakers. If your "system" relies on an unusual tight speaker matching, then probably not many people will use it because it just would not work for them.

Can you describe the "null cancel test"?
 
Can you describe the "null cancel test"?

perhaps this is it:

Under the general heading of tests it may be relevant to describe Quad's own routine test, which I watched at the factory. A square pulse is fed to one loudspeaker, and the audio output from a B & K microphone observed on a storage oscilloscope, which shows an incredibly good representation of the original pulse. Next, pulses of opposite polarity are fed simultaneously to two units, with the microphone in front and between them. Moving the microphone produces a null, which becomes a straight line with no more than 0.5 dB adjustment to one inputl

http://www.quadesl.org/Album/InterviewsReviews/esl63rev1981p2.doc
 
Read the book!

oh Markus :sigh:

You know very well in what sense Ferstler (and also myself) used the word "omnidirectional" :(

real world "omnidirectional"

perhaps better word is polydirectional or reflecting speakers like Allison, Hegeman/Morrison, Shahinian, Walcott, Sonab/Carlsson, Ohm, German Physics, B&O, Mirage, MBL, Duevel, Time Domain (Jp), Linkwitz's Pluto and so on

they ARE (or were) there

yet they are not covered in the book, none of them

Toole discusses various contemporary and also historical designs but none of the above

this fact makes the book quite uninteresting to me
 
Hi,

Can you describe the "null cancel test"?

There are many versions. With the Speakers I helped design we actually close the ports (no sound out of the back) and place the two units of a pair face to face with around a 5mm gap, then we play out of phase (between channels) mono pink noise (I made a test/setup CD that includes such a track mainly actually for speaker setup).

The sound that remains is the sound that is not cancelled because there was no perfect channel match between drive units, crossover, amplifier and CD-player.

I remain positively surprised with just how much attenuation of the noise we gain, especially as in my reviewer days I used practically the same method to "burn in" review loudspeakers and hence I know just how often the cancellation is not very good (implying poor pair matching).

Note that my method described above includes the whole system from the CD/PC track onwards, including different DAC non-linearity between channels all the way to badly tracking volume controls and driver mismatches. If you have a tube that has a significantly higher amount of distortion in one of the units in one channel that too is audible in this setup, though I normally look at the FFT graphs from the QC testing to figure out something like that is amiss.

Ciao T
 
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in this very old review of Ohm speakers in Stereophile I have found observations that can shed some light on why omni speakers are considered by many audiophiles as having poor imaging:

Sonic Impressions
The Ohm Walsh 5 started things off in the "dead" end of my dead-end/live-end listening room. No matter where I positioned them in that end of the room, however, their imaging magic was not to be heard. The almost palpable and spacious soundstage I had experienced under show conditions was gone. Instead, the soundstage width was restricted to the solid angle subtended by the edges of the speakers, and the solidity of individual spaces within that soundstage was marginal.

Acting on the suggestion of Don Bouchard at Ohm, I repositioned all of the absorbent material in the room so that the dead end became the live end and vice versa. It worked! The transformation was incredible. The dimensions of the soundstage stretched clear out to the sidewalls with excellent depth. The diffuseness of individual spaces within the soundstage increased somewhat, but each space took on a convincing 3-D quality. The focus within the soundstage was not ultra-tight, being more typical in extent of what you might experience from the back of the concert hall. It might be more accurate to say that the whole end of the room appeared to come alive; I got the distinct impression of peeking into a real space. A very enjoyable experience. One may conclude that the Walsh 5 does need a fair bit of room reflection really to shine, and that the dead-end/live-end arrangement suits it quite well.
see: Stereophile: Ohm Walsh 5 loudspeaker

it seems that omni speakers are not tolerant of typical audiophile listening room acoustics that is rather on the dead side
 
Hi,

in this very old review of Ohm speakers in Stereophile I have found observations that can shed some light on why omni speakers are considered by many audiophiles as having poor imaging:

see: Stereophile: Ohm Walsh 5 loudspeaker

it seems that omni speakers are not tolerant of typical audiophile listening room acoustics that is rather on the dead side

Funny, when not placed in "acoustically dead rooms" I would completely agree with Stereophiles (or rather the writers) assessment. I would probably weight the emphasis differently, but he clearly heard what I heard with similar "omni's":

Stereophile said:
The dimensions of the soundstage stretched clear out to the sidewalls with excellent depth.

Read the Soundscape was confined to within the room and the walls where clearly audible - or what I call the "they are here" effect.

Stereophile said:
The diffuseness of individual spaces within the soundstage increased somewhat, but each space took on a convincing 3-D quality.

Read - everything was diffusely spacious (due to a lot of in room reverb and a very long RT60) - but without being able to clearly focus on individual instruments in the soundscape.

Stereophile said:
The focus within the soundstage was not ultra-tight, being more typical in extent of what you might experience from the back of the concert hall.

Yes, read "back of hall perspective - plenty of long delayed reverb, much more reverb than direct sound, you can tell the Violins are on the left - sometimes.

I know that these are the expensive seats, just as well to as being in audio does not make you rich... :)

Stereophile said:
It might be more accurate to say that the whole end of the room appeared to come alive;

Yes, classical "omni" presentation. The room is filled with sound, it is pleasantly spacious but it is INSIDE THE ROOM and it has non of the spacial and directional characteristics of the original recording.

Honestly, having heard on more occasions than I care to admit, the Bose 901 does this job EVEN BETTER than supposed "True Omni's". They produce even more diffuse, spacious, reverby sounds than Omni's. If you don't believe me, try it!

Honestly, it is quite trivial to attain such a soundscape presentation. It was all done in the 60's and 70's. No real improvements in that department since. The Grundig Audiorama and Bose 901 had it all well sorted by then...

BTW, for those who do not remember the Audiorama's:

An externally hosted image should be here but it was not working when we last tested it.


Well, at least now we REALLY know why Logan was running. He was running away from ill focused, diffuse and boring Omni Sound... :p

Ciao T
 
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Hi,

I'm not sure if this is a feasible test because the setup is essentially a ported single speaker design. Have to think about it.

Ports can be closed temporarily. We actually supply foam for that (also for just attenuating port output) to suit our speakers LF output to room and placement.

Single Driver speakers however do show pretty poor pair matching, so you may not want to try this test, you may be disappointed.

The ones we test have a magnetostat HF Device is a Horn (nee. Waveguide) with a 10" LF Cone Driver and a 10th order crossover (passive) at a fairly low frequency.

If the drivers match to better than 0.5dB and the crossovers match too (at this rate of slope even small tolerances have big effects - so we pair not just drivers but also crossovers) the resulting null in this test is majorly impressive.

I once had a pair running in at a gentleman's home in a large high rise building with at best okay sound isolation. The speakers where run with the matching amp near clipping (this would be 110dB peaks @ 1m - per speaker) for a week day and night and with only a thick blanket to muffle the remainder a little more. No neighbours complained about the noise and the one asked could not hear it!

It was practically inaudible outside the flat door, the flat being in Hong Kong was on the small side and the walls not thick, even by London/Britain standards...

Ciao T
 
...
"Yes, classical "omni" presentation. The room is filled with sound, it is pleasantly spacious but it is INSIDE THE ROOM and it has non of the spacial and directional characteristics of the original recording."

etc.

Nice interpretation Thorsten ...

IMO you are damned close to reality.

BTW i sometimes thought about building a Bose 901 clone for
fun. But i had always projects in mind which seemed to be more
reasonable to me.

I think this article tries to explain some effects involved without
judging or hyping it too much.

http://www.stereophile.com/standloudspeakers/425/#


AFAIK the Audiorama is back in store again ... they produce
a new series. I do not know whether the technical design changed much.
 
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Hi,

...Nice interpretation Thorsten ...

IMO you are damned close to reality.

Thank you. I have heard quite a few Omni Systems (as you know, germany has a penchant for them, just as for ridiculous horns and other excotica, very unlike the US and the very proper english, but not as bad as the french).

I lived until 94 in Germany, until early 89 in the wrong halve though.

BTW i sometimes thought about building a Bose 901 clone for fun. But i had always projects in mind which seemed to be more
reasonable to me.

Back in the wrong halve of Germany before 89 we cloned the B*se 802 as well as the Zeck 15/3 for "PA" use. From a 802 to a 901 it was a small step. When we made a pair of 802's in solid Alu for fun (and pay) I made a pair of 901's in solid alu for my place. With one driver in the center of the nominal front and highly polished Alu they looked stunning. Of course we used much better quality drivers than B*se and needed less HF EQ.

They where sold on very quickly, as I could not stand listening to them, even used the wrong way around... :) I concluded then and there that Amar B*se was descended from indian fakirs (or is that fakers).

So I put the decidedly more homely Schulze TH315 based coaxial speaker system (with shortened stand) back. Later I replaced that with my own column design using a pair of 20cm woofers under active control (microphone - ala B&M), a 12cm Schulze wideband driver and the typical east german plastic dome, soon replaced by a Motorola "lemonsqueezer" piezo tweeter.

I kept the TH315 together with a pair quite "fatherless ones" Klipsch Cornwall semi-clones using all EV Drivers/Horns in my bedroom as monitors for mixing down stuff.

Never had Audiorama's though, but heard them much later in 2nd hand stores. At the time I used JBL Control 1's, even against such low competition they did not impress. Looked pretty cool though, in a 70's & Lavalamp kind of way.

AFAIK the Audiorama is back in store again ... they produce a new series. I do not know whether the technical design changed much.

Ohhhmeegawd. The muthafunking seventies are back again.

Oh well, did I not hear about a Movie remake of Logans Run as well?

Seems the music playback industry matches the music producing industry - if you cannot innovate, just rip off the last three deacdes and make it a certain hit:

4753.jpg


No wonder the kids are GaGa for Lady GaGa...

Ciao T
 
Ex-Moderator R.I.P.
Joined 2005
Funny, my present experimental OB-OMNIs are apparently different than the rest....very focused and precise
But admittedly, I didnt expect that either, and its a big surprice
And driver are placed on the floor, which is even worse
I cannot work, but it does

A great number of speakers are poor designs, and so probably also most omnis
 
Well, at least now we REALLY know why Logan was running. He was running away from ill focused, diffuse and boring Omni Sound... :p

lost in interpetation ;)

one interpretation or another, my interpretation of this Olsher's review is filtered by my experience with the flooders of course and I don't hear any of the following:

the Soundscape was confined to within the room

not true WRT the flooders, I can hear things happening far beyond walls

everything was diffusely spacious (due to a lot of in room reverb and a very long RT60) - but without being able to clearly focus on individual instruments in the soundscape.

not true WRT the flooders, actually I am more able to focus on individual instruments than in case of conventional setup

Yes, read "back of hall perspective - plenty of long delayed reverb, much more reverb than direct sound, you can tell the Violins are on the left - sometimes.

not true WRT the flooders, I can hear no such reverb when listening to "Kind of Blue" for example
and actually I have interesting test CD with tracks with different sections of an orchestra playing, everything is exactly in place and "reach out and touch"

classical "omni" presentation. The room is filled with sound, it is pleasantly spacious but it is INSIDE THE ROOM and it has non of the spacial and directional characteristics of the original recording.

not true WRT the flooders at all

perhaps it is indeed that the flooders differ significantly from typical omni
actually El'Ol insists that I shouldn't call them omni, perhaps I really shouldn't

Bose 901 does this job EVEN BETTER than supposed "True Omni's". They produce even more diffuse, spacious, reverby sounds than Omni's. If you don't believe me, try it!

"diffuse, spacious, reverby sounds"?

well, that is not what You get from the flooders!
and yes indeed - If you don't believe me, try it!

actually this is exactly what I tell everyone from the beginning of this thread

best!
graaf
 
Hi,

Funny, my present experimental OB-OMNIs are apparently different than the rest....very focused and precise
But if they cant design a good speaker of ordinary design, how then a good OMNI

Well, maybe.

Much depends on other factors. I once heard the same system to most intents (speakers where inndersound eros - aka KFC Speakers and an experimental amp plus dCs digital frontend) in two setups.

One was in a very long room, with heavy curtains at the end opposite of the listener, with the (dipole) speakers halve down the long dimension of the room room and the listening position at one of the narrow walls, IIRC heavy wall hanging carpet behind listening position and quite plush and absorbent sofa (a bit too victorian for my taste).

This kind of long, narrow living room is quite common in southern england BTW, it is the result of the terraced houses and knocking together the two small rooms previously serving respectively as parlour and as dining room.

I heard basically the same system a few weeks later in a similar size and shape room, this time placed very near one of the long walls with no intentional or incidental room treatment and the listening position opposite.

Predictably both systems sounded dramatically different.

The first was quite stunning, with a "the walls are gone" feel, the second sounded a bloody awful mess, with not even tonality right, never mind anything else, claustrophobic, brrrrrrr.

So, in the end how you use it matters a lot as well.

Me being kind of "1970's modern" inclined with my choice of living spaces (pretty bare, large if possible, white in both colour and acoustics) need quite well focused speakers to avoid drowning in reverb sauce. Put omni's in my rooms and even you run out like Logan.

Ciao T
 
Hi,

this Olsher's review

Who later designed a range of speakers with upwards pointing woofers and forward pointing tweeters. Just BTB.

the flooders

If you use the ceiling as the first reflection with a fllor that is heavily carpeted and hence quite absorbent this may work to a reasonable degree, I can see issues with tonal balance though.

If this implemented with drivers having a frequency response that is boosted at high frequencies and narrows at frequencies it may kind of work.

Where I tried the Carllson Sonab's the floor and ceiling where acoustically highly reflective. As is the case with my current living room.

I rather doubt that under those kind of conditions you would like your flooders, if you do, maybe I see pair of 901's or Audiorama's in your future?

:p

Ciao T
 
Funny, my present experimental OB-OMNIs are apparently different than the rest....very focused and precise
But admittedly, I didnt expect that either, and its a big surprice
And driver are placed on the floor, which is even worse
I cannot work, but it does

yes, it cannot work but it does, exactly! :)

happy to hear that You enjoy the experiment

the proof of the pudding is in the eating

best,
graaf