Adding ballast to speaker stands
melchionda
Posts: 79
On another thread I’m discussing my resto-mod project on a pair of Polk monitor 5 jr + speakers I bought back in 1988. Paired with these speakers were a pair of metal speaker stands. The brand and model escapes me, (they might be Chicago Speaker Stands) but I bought them back in the 80’s around the same time I bought the polk speakers.
The stands are made of steel ‘tubes” that are rectangular in cross-section. They are painted black and are intended to be filled with ballast. Back in the day I think lead shot was used. I never filled them but as a part of this project I figured I would. The only problem is that lead shot is poisonous and is expensive. I’ve seen silica sand mentioned as an alternative, but wanted to avoid that because I’m concerned that the fine sand grains could leak out of the stands. I’ve also seen concrete mentioned, but pouring concrete into the tubes of the stand seems difficult and messy. I recently came across steel blasting media. It seems to be cheaper than lead shot. But the other issue is the resonance of the steel speaker stand tubes and the ballast. It seems that the ideal material would be something that is heavy but also helps dampen the resonance of the stand and doesn’t vibrate and potentially make noise.
Anyone ever use steel blasting media?
Anyone have any other ideas on what to use for non-resonant ballast?
The stands are made of steel ‘tubes” that are rectangular in cross-section. They are painted black and are intended to be filled with ballast. Back in the day I think lead shot was used. I never filled them but as a part of this project I figured I would. The only problem is that lead shot is poisonous and is expensive. I’ve seen silica sand mentioned as an alternative, but wanted to avoid that because I’m concerned that the fine sand grains could leak out of the stands. I’ve also seen concrete mentioned, but pouring concrete into the tubes of the stand seems difficult and messy. I recently came across steel blasting media. It seems to be cheaper than lead shot. But the other issue is the resonance of the steel speaker stand tubes and the ballast. It seems that the ideal material would be something that is heavy but also helps dampen the resonance of the stand and doesn’t vibrate and potentially make noise.
Anyone ever use steel blasting media?
Anyone have any other ideas on what to use for non-resonant ballast?
Yamaha RX-A2080 HT Receiver in 5.4.4 configurationYamaha A-S2200 Integrated Amp Powering an extra set of Front SpeakersAudioLab 6000N Network Streamer Connected to Spotify and Amazon HD Music4 10" Subwoofers Powered By Dayton Audio 1200 DSP Amps4 In ceiling Atmos SpeakersSpeakers:Warfedale Diamond 9.1 (Front and Rear L+R)Polk Monitor 5 Jr+ (Front L+R)Martin Logan Motion SLM XL (Center Channel)Subwoofers 2x Dayton Audio RS270-8 10" Reference WooferSubwoofers 2x Dayton Audio RSS265HO-44 10" Reference Series HO DVC Subwoofer
Comments
-
Lead is only a problem if you're eating it, drinking from vessels made with it or inhaling a lot of lead dust.
Inside sealed speaker stands, nope.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
In my steel tubes I dropped about 8" of fine play sand then lead shot then more play sand. You could use all play sand it works good and definitely will not resonate.
-
Sand is said to help attenuate the vibration as heat from the friction of the quartz/silica grains rubbing against each other. Steel shot is more dense. Makes sense to do a combination for a speaker stand. Just saw a video the other day where they use it in the Swiss made top of the line Jean Mauer loudspeaker where the back is an inner layer of hardboard and outer layer of grooved chipboard with sand inside. They also use sand inside the double walled enclosures for the midrange and treble drivers.:
https://www.youtube.com/watch?v=FH3mmRLjKxU
https://www.jeanmaurerhifi.ch/annexes/catalogues/loudspeaker-technical-document.pdf#page=15
Post edited by Gardenstater onGeorge / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Wonder why they stopped at just using a pin/pointed rod on that MW to rear enclosure.
Was that Matt Polk moonlighting? He had a labcoat.Don't take experimental gene therapies from known eugenicists. -
Wonder why they stopped at just using a pin/pointed rod on that MW to rear enclosure.
Was that Matt Polk moonlighting? He had a labcoat.
I think the tapered needle (threaded into the hollow bushing) is to help establish laminar flow vs turbulent for the under dust cap back wave of the woofer and the screw (also threaded into bushing) on the back of the speaker is adjusted to compress the sand cavity and thereby adjust it's resonant frequency.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
In my steel tubes I dropped about 8" of fine play sand then lead shot then more play sand. You could use all play sand it works good and definitely will not resonate.
I vote all play sand.Don't take experimental gene therapies from known eugenicists. -
Gardenstater wrote: »Wonder why they stopped at just using a pin/pointed rod on that MW to rear enclosure.
Was that Matt Polk moonlighting? He had a labcoat.
I think the tapered needle (threaded into the hollow bushing) is to help establish laminar flow vs turbulent for the under dust cap back wave of the woofer and the screw (also threaded into bushing) on the back of the speaker is adjusted to compress the sand cavity and thereby adjust it's resonant frequency.
Our vintage MW stamped steel frames can handle a pre-stressed rod from pole-piece to back baffle.
Don't take experimental gene therapies from known eugenicists. -
Gardenstater wrote: »Wonder why they stopped at just using a pin/pointed rod on that MW to rear enclosure.
Was that Matt Polk moonlighting? He had a labcoat.
I think the tapered needle (threaded into the hollow bushing) is to help establish laminar flow vs turbulent for the under dust cap back wave of the woofer and the screw (also threaded into bushing) on the back of the speaker is adjusted to compress the sand cavity and thereby adjust it's resonant frequency.
Our vintage MW stamped steel frames can handle a pre-stressed rod from pole-piece to back baffle.
Yeah I watched the video again and there is not a vented pole piece on the woofer. So the prestressed spike/pin transfers the reaction force of the woofer back against the preloaded rear enclosure that is filled with sand. There is a viscoelastomeric foam rubber isolation scheme between the front baffle and the woofer so the baffle is somewhat isolated from the woofer.
We are corrupting this thread
George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Lead is only a problem if you're eating it, drinking from vessels made with it or inhaling a lot of lead dust.
Inside sealed speaker stands, nope.
I thought that it was also a problem if you were getting lead residue (dust) on your skin from handling it? I could be wrong.Yamaha RX-A2080 HT Receiver in 5.4.4 configurationYamaha A-S2200 Integrated Amp Powering an extra set of Front SpeakersAudioLab 6000N Network Streamer Connected to Spotify and Amazon HD Music4 10" Subwoofers Powered By Dayton Audio 1200 DSP Amps4 In ceiling Atmos SpeakersSpeakers:Warfedale Diamond 9.1 (Front and Rear L+R)Polk Monitor 5 Jr+ (Front L+R)Martin Logan Motion SLM XL (Center Channel)Subwoofers 2x Dayton Audio RS270-8 10" Reference WooferSubwoofers 2x Dayton Audio RSS265HO-44 10" Reference Series HO DVC Subwoofer -
In my steel tubes I dropped about 8" of fine play sand then lead shot then more play sand. You could use all play sand it works good and definitely will not resonate.
Where you anticipating that the sand and lead shot would mix together or were you going for layers of sand and then lead shot and then sand?Yamaha RX-A2080 HT Receiver in 5.4.4 configurationYamaha A-S2200 Integrated Amp Powering an extra set of Front SpeakersAudioLab 6000N Network Streamer Connected to Spotify and Amazon HD Music4 10" Subwoofers Powered By Dayton Audio 1200 DSP Amps4 In ceiling Atmos SpeakersSpeakers:Warfedale Diamond 9.1 (Front and Rear L+R)Polk Monitor 5 Jr+ (Front L+R)Martin Logan Motion SLM XL (Center Channel)Subwoofers 2x Dayton Audio RS270-8 10" Reference WooferSubwoofers 2x Dayton Audio RSS265HO-44 10" Reference Series HO DVC Subwoofer -
melchionda wrote: »
So, wear latex gloves.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
melchionda wrote: »In my steel tubes I dropped about 8" of fine play sand then lead shot then more play sand. You could use all play sand it works good and definitely will not resonate.
Where you anticipating that the sand and lead shot would mix together or were you going for layers of sand and then lead shot and then sand?
I had two bags of #12 lead shot. I wanted it near the bottom, I had a young crawler my EX was worried it would migrate out and he would get it on his hands and then to his mouth. So to appease her I put a buffer between it and the base plate. It wasn't going to come out and he was not going to get it in his mouth. The fine play sand was smaller and it never came out at all.
It was a pick your battle sort of situation. I was never going to used that small of shot for my reloading so I chose divide it up use it in the stands instead of tossing it. -
I layered dry sand and lead shot in one pair of stands. In another I mixed the shot and sand then poured it in. I don't think how it's added really matters. What I believe matters is the mass, the more, the better.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk
