4. It's All About Vibration & Resonance
PART 1:
Vibration and Resonance - Think of a Speaker as a Musical Instrument
People often ask how and why speaker stands, spikes and solid heavy plinths make a difference to the sonic performance of a speaker, well hopefully this edition of ‘Hifiology’ will explain why.
If we take for example stringed musical instruments such as the cello and double bass, these instruments are greatly influenced by the use of end pins and how the end pin effects the tonal characteristics and sonic signature of the instrument.
If we think of a speaker as a musical instrument, then the effect of the end pin is very similar to how speaker stands, spikes and solid heavy plinths greatly influence the tonal characteristics, sonic signature and overall performance of a speaker.
You’ll be amazed with the sonic improvements that are gained when using a solid heavy plinth underneath your speaker stand or floor standing speaker.
No more holes in your carpet when using spikes to pierce your carpet and underlay and no more tiny floor protectors for solid floors.
The following aims to explain comparisons between stringed musical instruments and various size speakers.
Stringed Musical Instruments
All stringed musical instruments have a tonal sound or signature sound unique to their size and the materials used in their construction.
Note: The strings vibrate and the body of the instrument resonates.
Strings
The thiner the string, the higher the frequency of vibrations
The thicker the string, the lower the frequency of vibrations.
Body
The smaller the body of the instrument, the less resonance in the lower register of frequencies.
The larger the body of the instrument, the more resonance in the lower register of frequencies.
Speakers
With regard to comparing stringed musical instruments and speakers, the tweeter and bass drivers perform in very similar ways to the strings on a stringed instrument, they vibrate and the speaker cabinet resonates.
Tweeters
The tweeter is very similar to the thin strings of a stringed musical instrument vibrating in the higher frequencies.
Bass Drivers
The bass driver is very similar to the thicker strings of a stringed musical instrument vibrating in the lower frequencies. The larger the bass driver, the more resonance in the lower register of frequencies.
Cabinet Sizes
Depending on the size of the cabinet it will either resonate more or less in the lower register of frequencies.
Similar to a stringed musical instrument, a speakers tonal or signature sound is unique to its size and the materials used in its construction.
How the speaker cabinet is supported or mounted will greatly effect the speakers performance with regard to cabinet resonance plus the vibrations of the tweeter and driver.
Cello, Double Bass and End Pins
The characteristic sounds of the cello and double bass instruments are greatly influenced by the use of the various woods used in their construction and different types of end pins and floor supports.
End pin rubber floor protectors, spike anchors plus floor protection discs all influence the sound of the cello.
The End pin was introduced to help support the cello as it was played by the musician, before the end pin was invented the musician would support the instrument by resting the instrument on the floor, supported either side by the player’s legs also known as ‘de gamba’ style.
This method would alter and dampen the resonance and volume of the instrument.
The wooden end pin, it is said, was invented by the cellist Adrien Francois Servais 1807 - 1866.
The Adjustable Height End Pin was first introduced in 1890 with the Fully Retractable Metal End Pin introduced in 1900.
End Pins can be made of the following materials:
Wood - Maple, spruce, mahogany, and ebony
Steel - Solid Stainless Steel, Tubular Stainless Steel
Aluminium - Solid Aluminium, Tubular Aluminium
Titanium - Solid Titanium, Tubular Titanium
Brass - Solid Brass, Tubular Brass
Carbon Fiber - Solid Carbon Fiber Rod, Woven Carbon Fiber Tube
Cello End Pin - Sound Comparisons -
https://www.youtube.com/watch?v=3XP3vdGWiUU&t=213s
Video Timeline Points
0.23 sec - Carbon Fiber End Pin
1.12 sec - Mitsuke Precision Triple Brillante End Pin - Three layers- Tungsten, Titanium and brass
2.03 sec - Berlin Sound End Pin - Stainless Steel or Titanium
2.53 sec - WWT Studio Cantabile End Pin
Double Bass End Pin - Sound Comparisons -
https://www.youtube.com/watch?v=k47-Ti-Bg94
Video Timeline Points
4.43 sec - Stainless Steel
4.58 sec - Wood
5.23 sec - Wood
5.42 sec - Stainless Steel
6.05 sec - Stainless Steel with Bow
6.23 sec - Wood with Bow
The Krentz Endpin - Silicon Nitrate Rod -
https://www.youtube.com/watch?v=blNqNqWVRyk
Strings on a Violin - G, D, A, E
Strings on a Viola - C, G, D, A
Strings on a Cello - C, G, D, A
Strings on a Double Bass - E, A, D, G
PART 2:
Vibration and Resonance - Speakers, Speaker Stands & Spikes
Speakers & Speaker Stands
Using speaker stands for stand mount or floor standing speakers greatly improves the speakers overall sonic performance.
One thing to remember is that once the speaker is placed on the stand, the speaker and stand become one, and resonate as one large vibrating structure.
Spikes
Using spikes or cones between the speaker and stand helps reduce the transmission of vibrations from the speaker to the stand.
The spikes achieve this reduction by minimising the point of contact between the speaker and the stand.
The idea being that the spikes point of contact is so small that a large waveform with high amplitude cannot not pass through at full strength.
The purpose of the spikes at the base of the stand is to further reduce the transmission of vibrations from the combined speaker and stand, by minimising the overall contact of the structure with the floor surface.
Speaker Stands, Spikes, Carpet and Underlay
Using spikes at the base of the stand or speaker minimises contact with the floor helping balance the stand with a minimum of 4 points of contact with the floor.
It is a widely held belief that the spike when used to the support the stand on a carpeted floor, only makes contact with the floor at the point of the spike.
This is incorrect, because as the spike penetrates the carpet it makes contact with both the carpet plus the underlay and then the floor.
It is this contact with the carpet and underlay that dampens and changes the tonal characteristics of the speaker.
The amount of dampening depends upon the thickness of the carpet pile and the underlay.
The thickness of the carpet pile and the underlay also influences the stability of the stand or speaker and this is why it’s advisable to use a solid heavy plinth, placed on top of the carpet, to further improve the stability of the speaker.
The heavier and larger the plinth the greater the stability and dispersion of the overall weight over a wider area, very similar to how a snow shoe operates.
Spikes & Their Threaded Length
The only problem using spikes is that most speaker manufacturers supply spikes with an overall threaded length of 30mm.
This length is far too small, as 10mm is taken up just inserting into the base of the stand or speaker, leaving very little thread to adjust for an uneven floor surface and correctly balance and level the stand or speaker.
The correct length should be between 40mm and 50mm, unfortunately spikes with an overall length of 40/50mm are hard to come by.
Using Cross Slotted - Mushroom Headed Screws - M6, M8, M10 with a Solid Heavy Plinth
Note:
The following is a suggestion and no responsibility is taken for any mishaps which may or may not occur whilst implementing this suggestion.
Please remember that this only a part of the setup required to improve your Hifi experience.
If you have any questions with regard to this edition of ‘Hifiology’ please do contact us.
“Notionally, this is something anyone could do themselves, but the level of ear-training and amount of experience David from the Listening Suite has precludes setting-up to this degree. Call in the experts! “
Alan Sircom, Editor of Hifi+ Magazine
There are many alternatives available to replace the feet, cones or spikes supplied by the speaker manufacturer.
All these alternative supports will influence the sound performance of your speaker, some more than others.
I have found that replacing the spikes with Cross Slotted - Mushroom Headed Screws with a thread size of M6, M8, or M10 and the increased thread length of 40/50mm greatly increases the ability to correctly balance and level the speaker stand or floor standing speaker due to uneven floor surfaces.
Note:
Most speaker manufacturers use either M6, M8 or M10 threaded inserts in the base of their stands or speakers.
You will also need to purchase the appropriate sized NUTS and WASHERS for use with the screws.
Note:
The M6, M8, M10 - Cross Slotted - Mushroom Headed Screws must only be used in conjunction with a solid heavy plinth base and not placed directly onto carpet.
Plinth suggestions for a Speaker Stand or Floor Standing Speaker
Placing a solid heavy plinth under the speaker stand or floor standing speaker greatly reduces the speakers contact with the floor plus improves the speakers positioning and overall sonic performance.
Whether the floor is carpeted or is a solid wood floor using a plinth under the stand or speaker will greatly improve the performance of the speaker.
A plinth offers a far more stable surface on which to place the speaker stand or floor standing speaker.
With the aid of a solid heavy plinth, the feet, cones, spikes or screws are now making minimum contact with the plinth and less contact with the floor.
The plinth can be used with the feet, cones or spikes supplied by the speaker manufacturer or other alternatives, such as Cross Slotted - Mushroom Headed Screws.
The larger the plinth the greater the stability and dispersion of the overall weight over a wider area, very similar to how a snow shoe operates.
The polished surface of the plinth allows minute changes in the positioning of the speaker, precise to within millimetres, by sliding the stand or speaker upon the polished surface of the plinth.
This amount of fine adjustment can never be achieved when the stand or speaker is positioned using spikes to pierce a carpeted floor.
Equipment racks can also benefit from the stability provided by the use of a solid heavy plinth.
The following images offer some suggestions with regard to constructing a plinth for your speakers.
Plinth sizes can be 400mm x 400mm, 500mm x 500mm, or 600mm x 600mm (The size of the plinth as seen in the photo is 600mm x 600mm)
Rubber Matting
Felt Pads
