Instantly deepen your sub? - Page 2 - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

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 2nd November 2010, 08:19 PM   #11
diyAudio Member
 
Join Date: Jan 2008
Location: Toronto and Delray Beach, FL
Might be safer in your bloodstream than clogging your lungs and depriving them of air.

No, helium doesn't seem backwards: it seems the "natural way" what you are proposing. But I don't think it is right.

No trouble getting tweeters go supersonic and far, far higher than most ears go.

But getting lower distortion, linearity, and damping from proper impedance match will always be a problem except for gas-speakers. That's my take on the physics.

Of course, I'm the ESL guy who is always ridiculing cone speakers which shake big hunks of heavy cardboard to make sound in thin air.
__________________
Dennesen ESL tweets, Dayton-Wright ESL (110-3200Hz), mixed-bass Klipschorn (35-110), and giant OB using 1960's Stephens woofer (20-35); Behringer DSP. HiFi aspirations since 1956
  Reply With Quote
Old 2nd November 2010, 08:20 PM   #12
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

Heavy gas is not what you want inside a subwoofer, the lighter the gas
the better as I recall. I seem to remember some speakers allegedly
loaded with helium filled plastic bags to increase effective box volume.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
  Reply With Quote
Old 2nd November 2010, 08:39 PM   #13
onform is offline onform  England
diyAudio Member
 
onform's Avatar
 
Join Date: Apr 2008
I wonder what would happen if you placed and sealed a large helium filled balloon over the front of a driver and pointed it upwards? would you get a huge low mass omni directional driver? you could even have a tweeter mounted coaxially inside on a rod pointing forward as presumably higher frequencies would just past straight through? If you filled all but one mounting holes you could use the last and mount a valve in it??

Or am I just bonkers?
  Reply With Quote
Old 3rd November 2010, 11:07 AM   #14
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
"the lighter the gas
the better as I recall. "

That's backwards. The gas must be denser than air. The air load presented to a driver is a poor impedance match because the air is so light compared to the speaker cone.
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 3rd November 2010, 03:22 PM   #15
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Quote:
Originally Posted by djk View Post
"the lighter the gas
the better as I recall. "

That's backwards. The gas must be denser than air. The air load presented to a driver is a poor impedance match because the air is so light compared to the speaker cone.
Hi,

Nope. It has nothing to do with impedance matching. Lighter than air
gases make the effective box volume appear larger and heavier than
air gases make the effective box volume appear smaller. In the accounts
I've come across only hydrogen or helium is "apparently" suitable. Some
accounts talk about using heavy gas to restrict movement, but that
is pointless, just use a smaller box or restraining volume if needed.

Quote:
Hydrogen and Helium are the only gases readily available with inversion temperatures at or below the ambient temperature of the human environment.

It will be found that a gas with a negative Joule-Thomson coefficient will have a very high adiabatic compressibility, yet will have a relatively low isothermal compressibility; therefore, at mid to low frequencies the compliance of this gas is very high, but at ultra-low-frequencies in which the compression process is isothermal the compliance is very low and the response of the loudspeaker system is limited at infrasonic frequencies. As will be seen in the preferred embodiment of this invention, this is a very advantageous situation when applied to loudspeaker technology. "
I cannot remember where I read about the helium bags.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 3rd November 2010 at 03:25 PM.
  Reply With Quote
Old 3rd November 2010, 04:16 PM   #16
diyAudio Member
 
Join Date: Jan 2008
Location: Toronto and Delray Beach, FL
Quote:
Originally Posted by sreten View Post
Hi,

Nope. It has nothing to do with impedance matching. Lighter than air
gases make the effective box volume appear larger and heavier than
air gases make the effective box volume appear smaller.
As I poorly understand these things, you are right that the result is like the box is smaller if a heavier-than-air gas is used. But I think that is no different than saying the impedance match is better or that smaller boxes make the interior compression a bigger part of the compliance. I'm not sure if there is a benefit that couldn't be achieved by adjusting box size... dunno.

The real benefit of the heavier gas is at the front side of the cone. If the room were full of SH6, the cones would work better due to better impedance match. But that can't be done unless you wear a SCUBA mask and tank while listening to music.

But if you use the "megaphone" design, you get some of the advantages in proportion.
__________________
Dennesen ESL tweets, Dayton-Wright ESL (110-3200Hz), mixed-bass Klipschorn (35-110), and giant OB using 1960's Stephens woofer (20-35); Behringer DSP. HiFi aspirations since 1956
  Reply With Quote
Old 3rd November 2010, 05:11 PM   #17
diyAudio Member
 
Join Date: Oct 2010
Heavier gas, slower speed of sound, longer transit time through box, 'bigger box'. Doesn't that make sense?
  Reply With Quote
Old 3rd November 2010, 05:44 PM   #18
diyAudio Member
 
imfree707's Avatar
 
Join Date: Oct 2010
Location: Tenn Loop Ranch, Lebanon, Tn.
Send a message via Yahoo to imfree707
Default Lack Of SF6

I don't know about sulfur hex "deepening" the sound of subwoofers, but lack of SF6 made a hell of a noise in this "switch"!

You Tube-500kv Arc
YouTube - A 500KV three-phase switch failing to interrupt a 2,000 Amp arc Boulder City, NV (Lugo)

Impressive-sounding on a good system, especially the echo slap-back when that 50ft tall arc breaks!
__________________
A stiff power supply in a great-sounding amp is always better for you than a stiff drink.
  Reply With Quote
Old 3rd November 2010, 06:45 PM   #19
diyAudio Member
 
Join Date: Oct 2010
Yea, removing the insulator generally has that effect on high voltage equipment. SF6 is a dielectric. Had a similar experience fixing a power outlet that had been improperly wired from 3 circuits. 90% of my screwdriver vaporized. Well, it seemed as scary at the time.

Last edited by Seyeklopz; 3rd November 2010 at 06:50 PM.
  Reply With Quote
Old 3rd November 2010, 07:18 PM   #20
diyAudio Member
 
imfree707's Avatar
 
Join Date: Oct 2010
Location: Tenn Loop Ranch, Lebanon, Tn.
Send a message via Yahoo to imfree707
Default Agree!

Quote:
Originally Posted by Seyeklopz View Post
Yea, removing the insulator generally has that effect on high voltage equipment. SF6 is a dielectric. Had a similar experience fixing a power outlet that had been improperly wired from 3 circuits. 90% of my screwdriver vaporized. Well, it seemed as scary at the time.
I agree! The linemen saw the 50ft arc from a safe distance. Having a screwdriver explode into vapor while in your hand is actually more dangerous! The linemen weren't endangered by flying bits of molten steel!
__________________
A stiff power supply in a great-sounding amp is always better for you than a stiff drink.
  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
Fuse is blowing instantly (SSE) Divad89 Tubelab 14 14th September 2010 03:52 PM


New To Site? Need Help?

All times are GMT. The time now is 12:14 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