I have a pair of Thiel CS3.5 3-Way speakers that have Scanspeak 4-1/2" midranges (13M8621) used in a sealed enclosure. The magnet's
pole piece is vented to allow no buildup of pressure behind the non-porous (coated) center 38mm dome to vent when there is any excursion as a result of higher SPL's.
Question: Why would the pole piece vent is covered to seal in the back of the center dome to allow a scall subenclosure behind dome but the cone is allowed to vent to a 2 liter midrange enclosure?????
Why would Jim Thiel design this way. I would think it would cause some non-linearities/harmonic distortion as a result of the cone vents to a 2 liter enclosure while the center dome vents to a .001 liter???? enclosure in middle of magnet pole.
Can anyone explain the logic of this????
Thanks in advance...
pole piece is vented to allow no buildup of pressure behind the non-porous (coated) center 38mm dome to vent when there is any excursion as a result of higher SPL's.
Question: Why would the pole piece vent is covered to seal in the back of the center dome to allow a scall subenclosure behind dome but the cone is allowed to vent to a 2 liter midrange enclosure?????
Why would Jim Thiel design this way. I would think it would cause some non-linearities/harmonic distortion as a result of the cone vents to a 2 liter enclosure while the center dome vents to a .001 liter???? enclosure in middle of magnet pole.
Can anyone explain the logic of this????
Thanks in advance...
Clarification.... Any Comments???
For clarification there is a self-adhesive square "patch" that is secured to the back of the magnet that seals the vented pole piece.
I would assume that uneven loading of the dome versus the cone of this midrange would be detrimental?
Any logical explanation of why Thiel did this.....
I have replaced the 13M8621 midrange (fs =112 Hz) with the updated 13M8640 (fs=64 Hz) and was wondering if it was done to load the driver since it does not have the excursion/power handling capability as compared with this Rubber surround driver.
The 13M8621 had a paper-like surround (better coupling in midrange versus losing excursion capability as a trade-off)
Any explanation would be helpful as I was going to remove the square patch that I installed/transferred from the original failed drivers.
For clarification there is a self-adhesive square "patch" that is secured to the back of the magnet that seals the vented pole piece.
I would assume that uneven loading of the dome versus the cone of this midrange would be detrimental?
Any logical explanation of why Thiel did this.....
I have replaced the 13M8621 midrange (fs =112 Hz) with the updated 13M8640 (fs=64 Hz) and was wondering if it was done to load the driver since it does not have the excursion/power handling capability as compared with this Rubber surround driver.
The 13M8621 had a paper-like surround (better coupling in midrange versus losing excursion capability as a trade-off)
Any explanation would be helpful as I was going to remove the square patch that I installed/transferred from the original failed drivers.
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