ampage
Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. New: view Recent Searches.
New: visit Schematic Hell!
The sunn still shines online!

 
Listen to great tunes streaming live right now!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  

Why do magnets affect tone in humbuckers????


 
8/5/2005 5:04 PM
Duncan M.
email
Why do magnets affect tone in humbuckers????
Be gentle with me - it's my first post.  
 
I've been pondering this difficult question for some time now and I believe I have a possible answer.  
 
I have no practical expertise in winding pickups, this is purely theoretical and my theory is a little rusty.  
 
So before I make a fool of myself, can anyone else offer a convincing explanation of WHY stronger magnets apparently produce a brighter tone (with a given set of coils) in a humbucker?  
 
I realize that this is a fairly academic question and that you make pickups with whatever magnets you can get (or whatever sells), but I'd really like to understand what is going on...  
 
Thanks guys.
 
8/5/2005 5:37 PM
Dave Stephens
OK fellas lets rip this guy a new.......oh sorry, I'll be gentle :-) Joe Gwinn can probably give you an in depth tehcnical explanation but stronger magnets equal stronger output so a coil that is pushing out more voltage is likely to be pushing out a more full spectrum frequency response, well sorta. I think its kinda like when you turn down the volume pot on your guitar, the treble diminishes. This probably isn't technically correct but it works in theory. When you get into very strong magnets switching from alnico to ceramic then there is a definite reason here why the pickup gets brighter and thats because ceramic has no metal in it to load the coil down, no eddy currents are generated in the magnetic that kill the high frequencies.
 
 
  Monday
Book Of The Day The Ultimate Tone, Volume III by Kevin O'Connor
Have you ever wondered if there is a better way to build a Bassman, Champ, Plexi, an 800, AC-30, Bulldog or Portaflex? Or you wanted to build an SVT with off-the-shelf parts? How about a master-volume amp that doesn’t change tone with the master setting? Everything you need to know is right here, including: proper grounding techniques, wiring methods, and mechanical considerations. Eighteen chapters cover the “iconic” amps everyone knows and loves, with schematics and layouts for each, along with the technical history of the product. Eyelet-board and chassis-mounted tube socket construction is used throughout, for easy servicing and modding. TUT3 is very accessible even if you cannot fully read a schematic and is a "must have" if you are going to build an amp for your self.

Note: The Ampage Archive is an Amazon Associate site. A small commission is paid to the site owner on any qualified purchase made after clicking an associate link such as the one above.
 
8/7/2005 3:44 PM
Joe Gwinn
email

On 8/5/2005 11:37 PM, Dave Stephens said:  
quote:
"OK fellas lets rip this guy a new.......oh sorry, I'll be gentle :-) "
Wouldn't it be better to rip him a new mouth, so he could do solo two-part harmony?  

 
quote:
"Joe Gwinn can probably give you an in depth tehcnical explanation but stronger magnets equal stronger output so a coil that is pushing out more voltage is likely to be pushing out a more full spectrum frequency response, well sorta. I think it's kinda like when you turn down the volume pot on your guitar, the treble diminishes. This probably isn't technically correct but it works in theory."
That's exactly right, but the effect is physiological, not electrical - the spectrum doesn't change with output, but our perception of the spectrum does change. The reason is very simple - our hearing is most sensitive in the midrange, dropping off substantially at high and low frequencies, so at low volume levels, the highs and lows simply cannot be heard. The lower the volume, the more extreme the effect.  
 
The easiest way to verify this for oneself is to experiment with the volume on a stereo while playing the same CD over and over.  

 
quote:
"When you get into very strong magnets switching from alnico to ceramic then there is a definite reason here why the pickup gets brighter and that's because ceramic has no metal in it to load the coil down, no eddy currents are generated in the magnetic [metal] that kill the high frequencies."
Exactly right. The strength of the magnet has no direct effect on the brightness, although if the magnets are too strong the physical motion of the string will be affected by the magnetic pull, causing wolf tones. If the distance from pickup to string is increased, the output will be reduced a little and the wolf tone will be reduced a lot more, so there's an optimum to be found.

 
8/7/2005 4:29 PM
Duncan M.
email

quote:
"the spectrum doesn't change with output, but our perception of the spectrum does change. The reason is very simple - our hearing is most sensitive in the midrange, dropping off substantially at high and low frequencies, so at low volume levels, the highs and lows simply cannot be heard. The lower the volume, the more extreme the effect."
 
 
So you're saying that it's just down to the Fletcher-Munson curves Joe?  
Then if we had two identical guitars fitted with identical pickups BUT with differing magnets, playing through identical amps and cabs with identical tone & master volume settings,  
 
and then set the input level to achieve the same SPL - they should sound the same??????  
OK it's an impossible experiment....  
 
Seriously though, if it was just an output thing then you could make an A2 pickup sound like an A5 pickup by turning up the input stage of your amp a bit.... Or by playing harder !!  
 
I was sort of hoping someone would want to talk about recoil permeability........  
[hint, hint.]
 
8/7/2005 5:42 PM
Joe Gwinn
email

On 8/7/2005 10:29 PM, Duncan M. said:  
[QUOTE]Joe said "the spectrum doesn't change with output, but our perception of the spectrum does change. The reason is very simple - our hearing is most sensitive in the midrange, dropping off substantially at high and low frequencies, so at low volume levels, the highs and lows simply cannot be heard. The lower the volume, the more extreme the effect."  
 
So you're saying that it's just down to the Fletcher-Munson curves Joe?[/QUOTE]Yes, that's exactly it.  

 
[QUOTE]Then if we had two identical guitars fitted with identical pickups BUT with differing magnets, playing through identical amps and cabs with identical tone & master volume settings,  
and then set the input level to achieve the same SPL - they should sound the same??????  
OK it's an impossible experiment....[/QUOTE]Not different magnets, but the same magnet but with differing degrees of magnitization. The magnet size, shape, and material all matter.  

 
quote:
"Seriously though, if it was just an output thing then you could make an A2 pickup sound like an A5 pickup by turning up the input stage of your amp a bit.... Or by playing harder !!"
A2 abd A5 are different alnico alloys, so there may be more to it than magnetic strength. This would have to be settled experimentally.  

 
[QUOTE]I was sort of hoping someone would want to talk about recoil permeability........  
[hint, hint.][/QUOTE]We have, some months ago. Search for recoil and/or incremental. There was talk of doing some A-vs-B experiments, but no results were ever posted and the thread died out.

 
8/7/2005 7:09 PM
Duncan M.
email

Thanks Joe,  
I have searched for "recoil" & "incremental" without success.....  
 
What was the forum's thinking about the significance of recoil permeativity in this previous post?  
Can anyone sum it up for me?
 
8/8/2005 5:56 AM
Dave Stephens
Dig through the forum and maybe you'll find it, there's an archive in a weird spot that maybe someone can point you to. But for alnico 2 its supposedly not as quick pick response, more woody tone, I dunno I haven't done much A2 experimentation but going to try it in my P90s and see if its something noticeable at all. I did do some measurement tests and A2 actually increases inductance readings if you swap out from A5 bar mags in a P90. Slight but measurable, but I haven't listened to the change either. Someone could spend years testing all this stuff and it would end up being private research anyway. I would like to see comparisons between A5 magnets magnetized to A2 and A3 levels of gauss and then see if anyone can hear the difference between that and real A2 A3 mags. Andy says he can hear a difference but thats just one set of ears. Like I said you could spend years on this stuff. Most of us experiment and find out what works that players would like to use and if we have time or obsessive interests try to fit that in between the work a day world......
 
   Page 1 of 4 Next> Last Page>>