Better Than Cones/Sex

Today I visited an auto wreckers and scrounged for free a handfull (6) of engine valve springs in order to repeat an experiment that I performed around ten years ago.
This experiment is to mount the loudspeakers on 3 automotive valve springs - 1 spring under each of the bottom front corners of the cabinet, and 1 spring centrally at the rear.
In my workshop I have a pair of Canton GLE-100 3 way (German made and all diecast and Canton branded drivers, heavy, dead and fibreglass mat filled rounded corner cabinets, nice cardboard cone 12" with vulcanised rubber convex surrounds, 2" soft dome mid and 3/4" soft dome hf ), placed at shoulder height on my 10m long quite solid equipment shelf.
A look at my workshop will give an idea - the photo is out of date - those speakers are 6 1/2" 2 way Boston A40 speakers and different amps and source items presently.
Nowadays I am running a 120W+120W DC coupled Jap (old Akai high end) power amp with an outboard 2 transformer/4 isolated DC rails power supply box, 10 pair telephone wire speaker cable, fed from whichever source component via a signal transformer isolation box with reversing switches feeding the primaries so that I can choose final absoloute polarity.
I have tried cones, wooden drawer handle knobs placed either way up, 2cm diameter glass marbles each placed on an o'ring to stop them rolling, soft and hard foam, black rubber and clear rubber pads, carpet pads etc etc in the past in order to explore the loudspeaker mounting options.
It has only taken me 10 years to get a round tuit to confirm my opinion and experience of back then - my knowledge, experience and criterion have changed since then of course, but in this case they still agree.
I confirm that I am getting reduced mids distortion and an overall cleaner, quieter, and more relaxed sound signature, more efficiency, more tuneful bass, more tuneful vocals and more tuneful highs that are very nicely amenable to tone control enhancement/tuning on both my workshop SS system and home Pc/Vcr/Tv/Audio work/play/learn station15W+15w all tube reciever and those Boston A40's.
I typically long term listen to these systems in nearfield, but I regularly go for a sound check walk around including going outside, and this reinforces my nearfield findings.
An additional benefit of this mounting arrangement, both in my past and now recent experience is much reduced coupling into the surface that the speakers are mounted on which results in much reduced acoustic feedback to source devices on the same surface.
I find the dynamic characteristics to be sonically nicer nearfield and farfield - tomorrow I'll go and cadge some more of these springs and try them under the electronic equipment and see/hear what I get.

Eric.
 
Do you still have your speaks sitting on a shelf? Is this an isolation from the shelf to keep it from becoming a transducer exersize?
You still going to try the silly putty?
And since you seem undaunted by convention like myself I will pass on a tip I picked up last week from a pro installer. This is for his system not his clients. He uses under gear that is not prone to picking up harmonics like SS amps a very dense material that does not pass vibration instead of something soft to absorb the vibration. You might want to get some to use as feet/bases for the springs.
Hockey pucks.

David
 
Springs under your speakers?

Ok this sounds crazy to me, I thought the idea was to damp vibrations rather than to couple them?

What happens when the springs reach resonant frequency?

2PI*ROOT(M/K)

...and the overtones of that frequency?

This is strange, I can truly say I've never heard of this being done before!


:confused:
 
Annex, I find the overall sound to be bigger, nicer and more dynamic by allowing the box to 'float' on 3 springs.
Mids are nicer and efficiency is improved in the two systems currently using these springs.
My bass is now going lower and more open sounding, and resonance of the springs does not seem to be a problem.

Try it and you might like it.

Eric, The Trendsetter.
 
annex666 said:
Springs under your speakers? ... I can truly say I've never heard of this being done before!

I am sure that the resonant frequency of the spring/speaker mass will come into play. As to previous use, the PEARL PR-2 used springs to mount the tweeter pod so as to decouple it from the midbass enclosure. I'll see if i can dig out his white paper and check to see if it has any concrete info.

dave
 

roddyama

Ex-Moderator
2002-01-19 9:25 am
Michigan
Eric,

Certianly if your happy with the sound, then it's right for you. Although I can see the point that Annex:devilr: is trying to make. Mechcanical resonances with that much mass will fall in the range below 100Hz and usually below 40Hz. There are only three ways to deal with a mechanical resonance:
1.)Move it outside the operating range by adding or subtracting mass or spring rate or both.
2.)Remove the excitation (which would be the driver in this case, so that's out)
3.)Dampen the resonance (which you haven't done)

Tone arms resonances are typically tuned to the 8Hz to 12Hz range so they will be above the warp region and below the audio range. It would be interesting to see where your resonance is. Maybe, if you're interested, you could take one of your frequency generators and run a sweep through you speakers from 100Hz down. The resonance point should be apparent because there should be visible movement. I would guess it would fall between 10Hz and 20Hz

You know this has the opposite effect of using spikes.
Rodd Yamas***a
 
DEcoupling

Dave and Rodd,

Certainly the spring mounting instead of cone or direct floor mounting changes a whole bunch of resonances in the cabinet, mounting surface, room, drivers etc.
I have found the same PA cabinets to sound different when mounted in similar positions in space according to whether standing on milk crates or flown, with flown better imo.
I'm finding things like I am preferring the boxes to float on quite lossless springs and not fast coupled to anything really, and allowed to operate on their own, and not hard coupled into the mounting surface.
A quick push on the front of the cabinets gives a rocking frequency of only a few hertz on the 61/2" two way cabs and lower on the bigger cabs.
A hand on the cabinets gives lower level and less harsh feeling vibrations, and the cabs seem to couple into the room better.
I have thought of filling the spring interwire spaces with a web of silicone sealant to provide spring damping, but have not tried it yet.
Also I have not tried sweeping and finding resonances and tuning them yet.
I also thought of mounting a cone or ball on the top of the springs and see what gives.
My thoughts are along the lines of choosing a suitable strength spring and and fine tuning the cabinet mass to make a primary resonance sitting on a musical frequency.

Eric.

Dave, yes please see if you can dig out that info.
I remember 20 years ago that Jamo were pretty big on mounting
their (10" or 12" Phillips) bass drivers on grommets or some sort of compliant mounting arrangement with a driver diameter concentric narrow cylindical port setup.
The reviews were quite good at the time but I've not heard anything of this since ?
 
electricashman said:
all you need are some coilovers, springs with built-in adjustable air-oil shocks.

You may need to add a damper to your springs, try it.

This sounds slightly better in my opinion. Why not try mounting the system on just dampers? Be they hydraulic or pneumatic it's sure to be a better way to decouple the speakers from the floor than using just springs.
 
annex666 said:


This sounds slightly better in my opinion. Why not try mounting the system on just dampers? Be they hydraulic or pneumatic it's sure to be a better way to decouple the speakers from the floor than using just springs.

Its just like a suspension system you need coils to suport the weight, you need shocks to control movement and vibrations and you need control arms to keep the weight centered on the coil.


Here is a simple idea, use some half eliptical leaf springs as your feet for your box. They may be more stable then 5 little coils, then add a small shock from the floor plate to the box's bottom plate.

I could see that being an atractive design and the leaf geometry would eliminate the need for "control arms". the coils will alow movement left to rigth, front to back and side to side, you coudl make the leaft only alow up and down movement?
 
...you don't have to have springs at all, I don't know where this idea came from - this would be the case if the vibrational element that was to be isolated is not oscillating about a central point (although it must by nature of the loudspeaker).

A simple pneumatic suspension system could be implemented that does not use springs at all.


:headbash: :up:
 
I have to admit to not trying this "isolation" technique before posting, but I was only talking from a physics point of view and I did have a point.

Anyway if you want an idea for your next project maybe try some form of elastomer isolation?

The final word has to be...

"no matter what anyone else thinks about what you do to your hi-fi if it sounds better to you then it's worth it"
 
Free Energy Experiment.

"I'm finding things like I am preferring the boxes to float on quite lossless springs and not fast coupled to anything really, and allowed to operate on their own, and not hard coupled into the mounting surface."
It seems that the springs constitute a big impedence mismatch and are therefore not transmitting much power to the mounting surface - ie all the power stored as vibrational energy is staying in the box, and the box allowed to decay more naturally as opposed to all the energy of the bottom panel being quenched via cones into the mounting surface.
I'm now getting bigger, better and smoother bass, and my 12" 3 way cabinets are now exiting the suspended ceiling in my 140 m2 shop.
Who said cones are the best way to mount cabinets ?.
Like I said I got the springs for free from the local auto wreckers, so whatever the result, this is a costless experiment.
Try it and you might like it.

Eric,