Conference hips::uk_audioo

322.0. "Upgrade your system for 10p" by GENIE::MORRIS () Thu Nov 21 1991 10:00

    Well as you may have read from previous notes, having moved to a house
    with a large open plan living room (L shaped 40' x 45') my small
    Mission 70 Series II monitor speakers where sounding definitely lost
    in the Bass end.
    
    The previous house was a typical English modern box with a 12 x 15
    lounge giving ample room resoncae to fool me into thinking I had bass.
    
    The new room is not only much larger, but at on end there is a large
    well with a spiral stair case leading upto the landing an down to the
    cellar. Add to this the ceilings are higher and you have a resonably
    well damped set of acoustics ( a lot of air and odd shapes).
    
    So I set about the search in this conference and the US counterpart for
    info on Sub-woofers ( I had recently hear a demo of the BOSE AM5 sat/SW
    set-up and was very impressed )
    
    More of the Sub-woofers in other notes !
    
    On my travels through the conferences I noticed that others with
    similar problems had been advised to chech their stands rigidity.
    
    Now at this point must admit to be a total sceptic on the finer side
    of Hi-FI...eg Spikes,Gold Wire tec...
    
    Having said that my speakers where mounted on spiked stands because
    when I bought them I originally tried them on the bookcase where they
    where intended to go and they sounded awefull. The only alternative was
    to put them on stands so after a trip back to the shop I was the proud
    owner of s set of matching Mission stands with lethal looking spike
    things. You should have seen the Wifes face !
    
    Anyway back to the present. Having read the notes I went home an
    looked at the speakers. Yes they where a bit wobbly (but only if
    you pushed them fairly hard) and the spikes counter nuts had lossened
    up in their travels over hear. Oh well I thought, ity isn't going to
    make a blind bit of difference but while I am here I amy as well
    tighten things up a bit.
    
    So I did the following ( and only the following)
    
    	o Tightened all the counter nuts up 
    
        o Raised the front spike so that the speaker where leaning back
    	  slightly towards the wall over the C of G.
    
    	o Having done this I tried to wobble the speakers and noticed that
    	  because they where still 0.5cm off the wall (wonderful things
    	  skirting boards) they would still move backwards if given a hefty 
    	  shove.
    
    	  So in the spirit of if your going to to a job do it properly I
          I looked for something small but hard to drop between the back of
    	  the speaker and the wall. I found that a row of Staples from my 
    	  staple gun was just the right size (imagine this written up in a
    	  HI-FI mag !).
    
    	  I dropped these in place, the speakers weight wedging them in.
    
    Now for the moments of truth. Well I switched on the set an put a CD on
    not for a moment thinking anything would be different.
    
    I COULD NOT BELIEVE MY EARS:- 
    
    
    The difference wasn't subtle it was amazing. The bass had not only got
    lower but it was clean and sharp. The stereo "soundstage" which I
    thought was good before was suddenly opened up you could place all 
    the instruments right across it... But for the real shock !! The whole
    thing had suddenly gone 3D. The vocalist was now way behind the TV.
    
    Just to check I wasn't the subject of mass self hypnosis, I removed the 
    staples from behind the speakers and tried again. Back to normal no
    bass, no 3D etc.
    
    Well this Sceptic is having to do some really hard thinking ( apart
    from wondering how he can market rear speaker-wall spikes)
    
    So if any of you out there have speakers that are designed to work
    against the wall..... Couple them !!!!
    
    Lean them back and place something small and hard between them and the 
    wall... Let us know if it works......
    
    Chris..., 
    
    
    
    	

    ....another convert to the cheap astounding tweak club.
    
    It's a wierd hobby, but helluvalot of fun.
    
    Dave

Aha! Methinks you have discovered a way to convert your walls into radiating
elements.  It is a well demonstrated fact that the back panels of speaker
enclosures vibrate a lot.  Now, if your walls are timberframe construction
with some form of plaster or plasterboard, they can be excited at audio
frequencies very easily and as vibrating panels they become giant loud-
speakers.  This wall construction is standard in the U.S.of A.  Now if
the walls in question are masonry construction, cinder or concrete block
in either solid wall or cavity wall design, then I would guess that the
chance of exciting them to any great degree would be small.  What kind of
construction are they?  If masonry, and you have observed this dramatic
improvement, then your staples and spikes are really having some effect
on what the speakers can do on their own with the assist of some stabili-
zation.  This could be a very interesting line of investigation to pur-
sue a bit further.  I mind not confessing that I am a COLLOSAL SKEPTIC
regarding virtually any and all tweaks, so perhaps we can pin down some
of the spike mystique on a somewhat more scientific basis.  

Some 13 years ago we lived in an all masonry construction semi-detached
in Galway (Ireland). There was very little sound conducted through the
walls of that house.  The lad on the other side of the common wall did 
like to listen to rock and sundry other cacophony.  His kit was in the 
large upstairs bedroom.  What did happen was that the sound coupled to 
the timber frame floor and found its way into our house quite readily.  
Fortunately he moved away shortly after our arrival. (He couldn't stand 
my playing the flute?).  The new people were very quiet.  She was a piano 
teacher, but converted the garage into her studio.  It was on the far 
side of the house so we couldnt hear the tots practicing their lessons.

Bill

    This is a Swiss house and the Speakers are up against the main
    supporting walls which are made out of 12"" x 8" x 8" construction
    blocks... Infact the whole house,internal walls as well are made of
    the same material including the nuclear bunker downstairs !.
    
    There ain't no way the walls are moving !.
    
    The layout is fairly odd :
    
    
    	***************  Door way **********************
    	*					       *
        *			       Large Stairway  *
        .					       *
    	.				  Up/Down      *
    	. Window				       *
        .					       *  +centre image
    	*					       *
    	*			  **********************
        *			   SP	SYS	   TV  *
    	*					       *
    	*					       *
    	*					       *
    	*		   ----			       *
    	*		   |  |			    SP *
    	* Fire/		   |  |			       *
    	* Chimney          |  |	    Seating	       *
        *		   |  |			       *
        *                  ----                        *
    	*                      |---------------|       *
        *                      |_______________|       *
        *                                              *
    	***.......................***		       *
             Patio/Windows          *                  *
                                    .		       *
                                    . Windows	       *
                                    .		       *
    	                            *................***
    		
Hope that makes sense !!!
    
    Chris
    
    
    

    "There ain't no way the walls are moving!."   
    
     Most unfortunate.  This means that I will have to reduce my COLOSSAL
     SKEPTICISM to colossal skepticism.  MOST UNFORTUNATE!
    
      Bill

    Join the club... Perhaps we could form the nucleus of SA (Sceptics
    Anonymous)
    
    Chris...
    
    PS. If you haven'y already been there .. Go and look at note 2660 in
        the AUDIO conference... Its cracking me up !!!
    
    	Now where is my green marker !!!