Thanks Greg. Pardon my ignorance, but you keep mentioning BW, what does the acronym stand for ?
'Gap' is the distance between the VC and wall of the magnet, so the tighter the gap, the stronger the field in theory, though there's an optimum where 'less' results in 'less' [trade-offs, always with the freaking trade-offs], so considering all the trade-offs of over-hung designs, I'll take a 'weaker' under-hung to over-hung for any app in our acute hearing BW any day and one reason why Altec, etc., vintage drivers continue to be the reference to which all others are measured.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Thanks Greg. Pardon my ignorance, but you keep mentioning BW, what does the acronym stand for ?
BW, what does the acronym stand for ?
Bandwidth
You're welcome!
[Frequency] band-width
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
For the sake of friendly argument(and i will likely learn something from it) i would opine that "gap" refers to the total space in which the voice coil resides.'Gap' is the distance between the VC and wall of the magnet,
I would call the distance between the voice coil/former and anything else "clearance".
Folks need to understand that depending on the type of speaker, various parts will be found in different locations.
When i read "wall of the magnet" i immediately thought of a ferrite motor where the wall of the magnet is usually so far away from the gap area that it's not important to mention. However, in an alnico woofer the magnet resides within the the inner diameter of the voice coil former and forms some or all of the inner wall of the gap, sometimes with the addition of a polepiece to extend it's length as needed.
For example, in a 515/515B the voice coil and former cannot even see the magnet proper. It's buried below the polepiece. Also with a 515/515B(and many others) it is the front plate of the motor assembly that forms the outside wall of the gap.
This is all just my 02 and understanding, please correct me where necessary.
[IMG][/IMG]
Not all vegetables make good leaders.
Bowtie: So in your above pic- The pole piece is in the center, The magnet wraps around the pole piece and is lower "bottom of the gap", The rear cover is like a shield or director to keep and focus the magnetic field.
Did I get it right?
By my understanding, yes.Originally Posted by Elitopus1
Bowtie: So in your above pic- The pole piece is in the center, The magnet wraps around the pole piece and is lower "bottom of the gap", The rear cover is like a shield or director to keep and focus the magnetic field.
Did I get it right?
The pole piece gets it's name by being charged/coupled to one pole of the magnet. To form a magnetic field in the gap you need something to complete the magnetic circuit from the opposite pole of the magnet to a point(circumference) in close proximity to the central pole. In an alnico motor like the 515 it's that magnetic return pot that completes the circuit between the magnet and the front plate. In a ferrite motor like the 515G, the polepiece and back plate are connected to one pole of the ferrite donut, and the front plate is connected to the opposite pole of the ferrite donut..
Not all vegetables make good leaders.
BT,
You do 'tax' me sometimes
I 'framed' my response based on my 'quick/knee-jerk' interpretation of Licorne's statement, i.e. I prefer the performance of an under-hung's wider [width] gap [clearance = lower BL/higher Qes] over an over-hung's equivalent. Note that the gap 'clearance' is referenced to the magnet's 'north' pole.
I suppose he could have meant gap [the entire opening] 'depth', but IME designing solenoid, multipole electric motors, making VCs longer than absolutely necessary was a no-no, so an 'apples n' oranges' comparison to my way of thinking, but then I may still be missing the 'forest' for all the 'trees' of your original response.
Regardless, good that you 'taxed' me since in retrospect I should have clarified what all the term 'gap' can imply when discussing electrical motors and then giving my $0.02 worth, which inflation adjusted from when I was first exposed to the basics of this stuff in '56 = ~$0.003 today.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Could someone please tell me how to post pictures like GM . Thanks
I use photobucket. You just copy and paste the link
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