The Advantages of Floor Coupled Up-Firing Speakers - Page 149 - 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 29th July 2010, 01:56 PM   #1481
Banned
 
Join Date: May 2008
Location: Switzerland
Quote:
Originally Posted by Elias View Post
For a test, of course one would use modern elements in a similar design
That would probably be one of John's dipole designs.

Our brain is trying to make sense of all the information it receives, so it's not a great surprise that the sound is not perceived as coming from the floor if there are strong, early reflections from a higher location.
  Reply With Quote
Old 29th July 2010, 02:52 PM   #1482
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
Quote:
Originally Posted by markus76 View Post
That would probably be one of John's dipole designs.
Who is this John who has designed floor dipoles with ceiling firing tweeter? Link?


Quote:
Originally Posted by markus76 View Post
Our brain is trying to make sense of all the information it receives, so it's not a great surprise that the sound is not perceived as coming from the floor if there are strong, early reflections from a higher location.
I need to do wavelet analysis of my previous experiment with the floor box to really see the levels and timings of direct sound vs reflections. Then I'd like to compare that with the theory of the precedence effect.

- Elias
  Reply With Quote
Old 29th July 2010, 03:09 PM   #1483
Banned
 
Join Date: May 2008
Location: Switzerland
Quote:
Originally Posted by Elias View Post
Who is this John who has designed floor dipoles with ceiling firing tweeter? Link?
"Our" John k...
I was not necessarily talking about "floor dipoles" but about speakers that result in the same perception as the speaker you mentioned.

Quote:
Originally Posted by Elias View Post
I need to do wavelet analysis of my previous experiment with the floor box to really see the levels and timings of direct sound vs reflections. Then I'd like to compare that with the theory of the precedence effect.
Yes, would be very interesting and helpful to get the numbers.

As to the perception, I think there are two aspects. First, the ceiling reflection has an impact on summing localization (to my knowledge there's only one paper investigating vertical summing localization). Second, an increased ASW that makes sounds seem to come from an area between the floor and ceiling and not from a single point.
  Reply With Quote
Old 17th August 2010, 10:11 PM   #1484
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
Hello everyone,

Measurement time!

I did some measurement of my ceiling firing experiment from the post#1080
http://www.diyaudio.com/forums/multi...ml#post2133755.

There I placed a two way speaker on the floor beside a side wall. The speaker is facing towards the ceiling. I was listening more than 2 metres distance. The listening experience gave a little bit of contradictory feelings that time.

So today I placed the same speaker at the same location and measured impulse response. Then I calculated wavelet transforms to see how reflections behave in time-frequency domain. It shows the sound energy between 500Hz-20kHz up to 20ms. I choose 20ms to fit most of the first reflections into the picture.

For a comparison I measured the same speaker placed at 1m height facing the microphone. This would be the normal listening configuration. In both cases the flying distance to the speaker was about 2.5m. The microphone is placed at the listening position so it is above a leather soffa, this will generate some extra reflections!



Here's the speaker placed on the floor facing the ceiling:
Of course there are many reflections. Notable is for example that above 3kHz the strongest sound is not the direct sound but a reflection just after 5ms. Also the reflections looks like quite random. Reflection density is high. Also notable is that there are strong reflections arriving at 20ms.
Click the image to open in full size.


And here's the speaker at the 1m stand facing the mic:
Of course the direct wave dominates (at 0ms). Note: the reflection at 2ms is most likely due to the soffa. At 4ms should be the floor reflection, 7ms the ceiling reflection. Reflections have a trend to be attenuated fast as time passes during the 20ms observation period. High freq reflections die faster than in the ceiling firing arrangement.
Click the image to open in full size.


The ceiling firing arrangement gives (relatively) more high frequency energy during 20ms than the conventional direct firing stand placement.

Ceiling firing sounds very spacious. That maybe the best feature of such an arrangement!

However, as I mentioned earlier, ceiling firing lost some of the small detail of the recording that could be heard when direct sound dominated.

Interesting!

- Elias
  Reply With Quote
Old 17th August 2010, 10:18 PM   #1485
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
And here's a 'CSD' equivalent wavelets of the two cases, first ceiling firing on the floor and second forward facing on the stand.

Same axes, same amplitude scale, same measuring conditions as above.

The same observations are valid.


Click the image to open in full size.


Click the image to open in full size.


- Elias
  Reply With Quote
Old 18th August 2010, 11:44 AM   #1486
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Hi Elias!
Your measurements' results confirm those done earlier and posted in this thread by Oliver (el'Ol).

Let me draw Yout attention to some commercial flooders that I have discovered recently, especially to the two-way Carlsson inspired AudioPro "Qube", see:
http://www.audiopro.se/media.php?id_file=527
Mpl
Mpl


best,
graaf

ps.
As I have declared earlier above - I don't discuss in this thread anymore and I don't post here but I make an exception just for You to invite You to join in the other thread at Fullrange section
__________________
"high phooey and hystereo" - Yascha Heifetz
  Reply With Quote
Old 18th August 2010, 04:58 PM   #1487
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Very interesting measurements. llow me a few comments.

Quote:
Originally Posted by Elias View Post
Measurement time!

...

Here's the speaker placed on the floor facing the ceiling:

...

Click the image to open in full size.
This shows some interesting faccetts.

First, let's ignore for a moment the reflections (we come to that).

In the direct sound we see a that below 1KHz (that is in the frequency range that covers the fundamentals and first formants of most acoustic instruments there is severe lack of energy, which is filled in at low frequencies and at higher frequencies. Clearly this speaker is anything but "controlled directivity".

Most of this missing fundamental energy is visible after 7mS, meaning it is almost wholly reflected from the ceiling and re-reflected after bouncing of the floor (14mS).

Much other energy echoes around the room all across the bands.

It would an interesting second experiment to set a digital delay plugin to have a 7mS delay and try for a similar effect "by ear". The frequency dependence of the reverb will be hard to incorporate, still, it should be possible to come somewhat close.

I'd be interested if your comments when using a high quality artificial reverb with your forward facing speakers would be similar to those when turning your listening room into a reverb chamber? Are you game?

BTW, before becoming a hopeless Audiophile I used to have my "mastering" system also as my listening system. And I had very expensive digital reverbs and equalisers at hand. And at times I'd use a bit of extra reverb to make overly dry recordings to sound more "wet", more spacious.


Quote:
Originally Posted by Elias View Post
And here's the speaker at the 1m stand facing the mic:

...

Click the image to open in full size.
Again, this shows quite clearly the problems of using speakers with poorly controlled directivity, especially in the vertical plane. Looking for the ceiling reflection around 7mS shows it consists mostly of 2KHz - 5KHz. I suspect the speaker has a dome tweeter and a slightly large cone woofer seeing this.

The sonic effect of this reflection will be to promote mostly the "brightness" region in the human hearing and even though the level is quite low, it lies in the ears greatest sensitivity region.

So I think controlling the speakers vertical dispersion (foam or felt wedges will do nicely) will likely help the sound quality. Of course, it will not make "dry" recordings sound spacious.

Maybe adding a small upwards radiating full range driver with a limited passband and a sensitivity below the main system can add some of the spaciousness back, with a switch to switch this effect off when not needed?

Ciao T
  Reply With Quote
Old 19th August 2010, 08:53 PM   #1488
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
Hello Thorsten,

Thanks for the comments. Maybe I should emphasise the reason I did the measurement is I wanted to see how the early reflection pattern looks like in the ceiling firing placement, because I could not localise the speaker at the floor. In the normal arrangement facing the listener at the ear level there is no problems to localise this (mono) speaker in the room.

Some clarification of the reflections. As can be seen the first reflection arrives very soon only 0.6ms after the direct sound. This is because the speaker is placed on the floor beside a side wall. The tweeter distance to the side wall was only about 15cm.

The reason of no energy below 1kHz is because of comb filtering. This can be best seen from this wavelet where comb filtering ripples occurs most of the frequencies:
Click the image to open in full size.

What comes to the "controlled directivity" the speaker is not that bad in horisontal direction rather actually is quite constant and smooth. However, the vertical pattern is worse (you never see those in marketing literature ). The speaker is a two-way with 6.5" + dome in 12l box.

I don't think mimicing the reflection pattern articifially would sound the same because of different spatial distribution of the reflections. With reverb reflections would come from the same direction as direct sound. I do have some reverb units (not that high quality though), but I rather feed the reverb to 'surround' speakers located side back and not in front. The envelopement is maximised if the late reverb comes a bit sideways.

Overall I think better way to obtain more constant early reflections is to use omni at high frequencies. However, at midrange and low frequencies omni does not sound good to me and I rather use higher directive sources like dipole line arrays below about 1kHz.

This is, I belive, due to the fact that there are completely different mechanisms for a human to hear and process sounds below and above about 1kHz. Then why the deliverance should be the same for both regions?? There is no need, in my opinion. Better results can be obtained if both regions are optimised separately. This is what I'm trying to do.


- Elias
  Reply With Quote
Old 20th August 2010, 02:30 AM   #1489
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by Elias View Post
Some clarification of the reflections. As can be seen the first reflection arrives very soon only 0.6ms after the direct sound. This is because the speaker is placed on the floor beside a side wall. The tweeter distance to the side wall was only about 15cm.
In such cases it is better to place the tweeter as close as possible to the sidewall.

Quote:
Originally Posted by Elias View Post
What comes to the "controlled directivity" the speaker is not that bad in horisontal direction rather actually is quite constant and smooth. However, the vertical pattern is worse (you never see those in marketing literature ).
Yet as we can see from your measurements, the vertical dispersion is as important, if not more so than the horizontal one, in domestic conditions at least, usually with speakers at around 1m height, 2.4m high ceilings and carpeted floors at any...

Quote:
Originally Posted by Elias View Post
The speaker is a two-way with 6.5" + dome in 12l box.
I surmised as much. I think a 3-way with a smaller midrange may have done better.

Quote:
Originally Posted by Elias View Post
I don't think mimicing the reflection pattern articifially would sound the same because of different spatial distribution of the reflections. With reverb reflections would come from the same direction as direct sound.
Agreed. However I would still suggest this experiement.

Quote:
Originally Posted by Elias View Post
I do have some reverb units (not that high quality though), but I rather feed the reverb to 'surround' speakers located side back and not in front. The envelopement is maximised if the late reverb comes a bit sideways.
First, if you have a PC based source, adding high quality reverb is trivial.

Secondly, funny you should mention independent speakers and piping delayed signals to them.

One of my "snakeoil & voudoun" tweaks is place a fairly large number of specific resonators that are tuned to resonate at a wide range of musical frequencies around the room. These resonate slightly in sympathy with sound being played.

Their contribution is at such low levels that it bis not possible to measure reliably, yet the subjective effect on perceived space is rather obvious. I primarily use them behind the speakers, to afford a subjective 'disassociation" of sound from the speakers, yet placing also behind the listener does add to sense of envelopement.

Quote:
Originally Posted by Elias View Post
Overall I think better way to obtain more constant early reflections is to use omni at high frequencies. However, at midrange and low frequencies omni does not sound good to me and I rather use higher directive sources like dipole line arrays below about 1kHz.
This is arguably the polar opposite of how things are done nowadays, but makes some sense. I personally would suggest to use instead a directive HF source that matches the directivity of the lower frequencies and to ADD a lower level omni source for high frequencies.

If we do this, we end up in effect with something like the Briggs/Warfedale baffle shown above, which was designed for mono playback and used a fullrange driver with helper woofer radiating forward and generally covering the audible range plus a ceiling firing tweeter.

I did try something like that in my own open baffle setup which used supravox fieldcoil full-range drivers (this did provide essentially a flat response throughout most of audible bandwidth, up to maybe 12...15KHz). I normally had a forward radiating "Super HF" unit which mainly extended the HF response. I did try this with a lower crossover radiating upwards and thought the results had some potential.

I believe the principle is somewhat similar to the Mark & Daniel add-on Omni Tweeter and the similar device from Elac in Germany.

Ciao T
  Reply With Quote
Old 5th October 2010, 03:43 PM   #1490
AllenB is online now AllenB  Australia
diyAudio Member
 
Join Date: Oct 2008
Quote:
Originally Posted by gedlee View Post
...., and then I put a lot of absorbing material to fill the corners (behind and arround the speakers but all behind the drape) to help damp out the LF modes.
Wouldn't this be an issue, that the sound that would diffract around the cabinets is met with this "black hole" of damping? Wouldn't this "enhance" baffle diffraction (speaking of frequencies above schroeder, of course)? Would you need to use wedge style foam?
  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 03:04 AM
Floor Standing Speakers. gurpreetsingh Full Range 11 12th June 2012 07:42 AM
side/ rear firing speakers Good/Bad? mcmahon48 Multi-Way 1 6th February 2009 01:28 PM
How far can the driver of a down-firing sub be from the floor? The Paulinator Subwoofers 11 16th May 2007 09:10 PM
Woofer: side firing pair vs front firing? tcpip Multi-Way 13 9th September 2005 03:13 PM


New To Site? Need Help?

All times are GMT. The time now is 09:05 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