Grant Rider wrote on Tue, 12 September 2006 18:56 |
I want to know how this can work. |
John Roberts {JR} wrote on Wed, 13 September 2006 01:24 |
I suspect a great deal of benefit could be realized with only modest air flow. |
Grant Rider wrote on Wed, 13 September 2006 20:41 |
Something I thought about all day keeps bothering me: =John Roberts {JR} wrote on Wed, 13 September 2006 01:24 I suspect a great deal of benefit could be realized with only modest air flow. The air rushing out of the magnet hole blasts with woofer movement already. The air blasts are enough to move my pants leg! I think it must do a lot by itself. How can the fan do more with "only modest air flow"? |
John Roberts {JR} wrote on Thu, 14 September 2006 04:04 |
At issue is whether it's the same hot air moving back and forth vigorously or new cool air replacing the old hot air. |
Grant Rider wrote on Wed, 13 September 2006 23:18 |
I think you are right there. The air must be cool. The fan isn't needed because the air blasts from the cone are strong. Using the cone as the pump makes the fan not needed. There is no pressure differential offset problem that way either. |
Michael Hedden Jr. wrote on Mon, 18 September 2006 00:53 |
Didn't I see this in a Jason or Freddy movie or maybe it was that classic "Race with the Devil" where everyone screams run, run for your lives, it's back, the attack of the cooling plug thread! Mike Hedden |
Kerry Stansbury wrote on Tue, 10 October 2006 19:35 |
The Eighteen Sound 15LW1401 does have vents around the spider, a pole vent and six vent holes direct from the voice coil gap. I don't know how much additional forced air would improve it's performance. |
Tom Danley wrote on Wed, 11 October 2006 16:30 |
If you look around, you will see air transfer is the most common method available, everything from your car’s radiator to the heat sinks in your amplifiers use this approach, the air carries away the heat energy. |
Tom Danley wrote on Wed, 11 October 2006 16:30 |
A typical V-8 car radiator can dump about 50KW of heat and its not that big, it just takes airflow. |
Tom Danley wrote on Wed, 11 October 2006 16:30 |
Look at the link below which shows the effect of forced air cooling on a DC servomotor. This motor is similar to that used in a Servodrive and has stationary magnets with a rotating hollow wire armature (very similar to a Voice coil). These motors only have a cooling air path on the outside of the armature where the air path in my cooling Patent is on both the inside and outside of the VC. |
Tom Danley wrote on Sun, 15 October 2006 11:17 |
You say “They also both use conduction or radiation to carry heat to the fins.” Actually radiation is not a significant part of transferring heat from either a transistor or engine block to the radiator, it is conduction. Even amplifier heatsink convection is a conduction driven mechanism, when the air in contact is heated, it rises. |
Tom Danley wrote on Sun, 15 October 2006 11:17 |
Your still missing a major concept here. Consider your surface area argument and then consider that the motor that I linked has less exposed area than one could have with a modest sized VC. Even so, a vary large increase of heat capacity is demonstrated in its measurements via passing air directly across the hot conductors. Like the loudspeaker, the problem is not cooling off the case but cooling off the part producing heat which is much much hotter. |
Tom Danley wrote on Sun, 15 October 2006 11:17 |
You keep dwelling on cone offset, perhaps your also missing part of the concept here. Off set force is equal to area times pressure. Lets say you had a peak pressure of 2 inches H2O, (this is also a pressure of .074 PSIG). This pressure if applied as I had shown in the Patent, is applied at the VC pocket. |
Wayne Parham wrote on Tue, 17 October 2006 13:32 |
Very good point, John. Is Intersonics still around? Might be worth a call to his old boss at Intersonics, just to see how he felt about using this technology. Seems underutilized, nobody is using it as far as I can tell. Tom said Intersonics had no interest in the voice coil version of the patent. I'm sure they would license it for a song to Tom if licensing were needed. Might be a mute point because I think the patent expires next year, but I imagine Tom would contact his old boss anyway, out of courtesy. I think if Tom is really sold on this technology he could probably use it if he wanted. |
John Roberts {JR} wrote on Tue, 17 October 2006 13:46 |
If the patent becomes moot due to expiration in a year, one could start pedalling now because it takes time to tool etc, were one so inclined. |
Quote: |
...when I presented my AES paper on “eliminating power compression”, Doug B from JBL presented right after one of the first papers to acknowledge its existence... |
Tom Danley wrote on Tue, 17 October 2006 17:00 |
A couple things, radiation is how the heat from a light bulb filament heats the glass or how the heat from combustion is transferred in the “flash” to the metal around it. Heat does not radiate through metal, think like light, photons that is radiation and it isn’t comparatively significant until something is real pretty hot. Look up Doug Button’s paper, I think he had the breakdown. |
Tom Danley wrote on Tue, 17 October 2006 17:00 |
You say” Those work as a radiant cooler until they become hot.” Yet, like light, one can’t radiate cool or darkness, they are simply lower energy states. |
Tom Danley wrote on Tue, 17 October 2006 17:00 |
My point is that in order for the magnet to become heated, the air in the gap must conduct most of that energy, since the air is already hot, just remove it. |
Tom Danley wrote on Tue, 17 October 2006 17:00 |
Yes there is a tiny asymmetrical force proportional to cooling flow for a VC, but it is acoustically insignificant in practice and in the example above. |
Wayne Parham wrote on Wed, 18 October 2006 16:31 |
The asymmetrical force is obviously directly related to the air pressure, and therefore cooling air flow. The more flow, the more force. That's the main thing that concerns me about this cooling system. |
Tom Danley wrote on Sun, 15 October 2006 19:55 |
There is no resultant air pressure on the dust cap or cone, the only net force on the system is caused by the cooling pressure and end area of the VC (OD area – ID area). Some drivers now are made with a vent to this location, like some B&C drivers but the ones I have seen also have a matching set of holes on the front plate. These defeat the idea when a fan is used as the front holes give a much easier air flow path which doesn’t involve scrubbing up against the hot VC in the gap. |