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In Reply to: RE: I don't know if you guys remember or not a few years ago I had gone on a buying binge of woofers and posted by Michael Samra on February 22, 2015 at 07:49:55
Hi Mikey,
I think there is a way of testing, but I read it a long time ago, and I don't remember. I think they become less efficient when dropped or otherwise damaged.
Dave
Follow Ups:
Ok I just had to share dropping alnico story because it is almost scientific and kind of interesting. Even though I worked at a reconer we never dropped alnico drivers to see if they would discharge, they just came in weak and really not as often as you would think.
Control: A pair of JBL 2420 drivers machined for an Altec tangerine phase plug. The drivers were almost completely discharged and needed a big bump to get them back to the 19,000 gauss or so the drivers came with stock.
Setup: After getting the drivers back from being recharged at Great Plains audio in Oklahoma they were tested on the bench to have high output like the originals and now the added benefit of extended bandwidth of the Altec tangerine plug strong to output to about 15-16k and not starting to roll off at 12-13k and trailing softly up to 15K like an original 2420 or le85 with radial phase plug. No need for bullets anymore plus way more output than a bullet!!! 2420...turbo...
test: (neither test done on purpose...I think!???)
1 First drop of a single 2420 driver.
In haste to listen to this brand new resto-mod driver they were bolted to horns and placed on the stack in a 4 way studio monitor/pa rehearsal system. Before the 2420 drivers were mounted permanently the system was cranked up during a rehearsal. A single 4 ohm B&C 21" woofer on the bottom of the speaker stack hooked up to a Crest 8001 (which is pushing out a real 1200 watts per channel @ 4ohms) subsequently bounced one of the 2420's off the stack falling over 5 feet to the floor. I was not there to see it but the scar on the 2420 was obvious. Sand bags were now placed on the 2420's to hold them in place and the dropped one was tested to have almost identical output as the one not dropped and no settings on the crossover needed changing. I have a good ear from years of mixing music in the recording studio and trust them. I did not feel the need to drag out a test mic.
2.Second drop- again I was absent...hmm...and again somehow the 21" b&c woofer was able to bounce the same already bumped 2420, now with a sand bag on it, to the ground from over 5 feet for a second time!
3.Examination- this time I could hear a very slight drop in output of the dropped 2420 , the driver is still usable an a slight tweak on the electronic crossover matched the level up again but the dropped driver is going to be sent out for recharging just because.
Ok so my crazy buddy with giant speakers dropped his alnico driver from over 5 feet, twice! just you you out there in internet land do not have to do this...ever!
Remember 2" of packing always when shipping alnico drivers and this power loss form a sharp blow should never be an issue. UPS would not pay me one time because there was not 2" of packing around an item...a good idea for anything audio or delicate. I tell all the sellers on ebay shipping me stuff the 2" rule and have had not one bent rack ear since.
That is good to know since a lot of my vintage speakers have alnico drives (Sansui, Pioneer, Coral, JBL).
Dave
Yes alnico does loose power over a long period of time. Here is a little alnico field strength story. I have a 1957 strat replica and had JM Rolph, a very high end guitar pickup winder, make me some 1957 strat replica pickups with alnico magnets charged to what a 1957 strat pickup magnetic field would be at the year I bought them. I had been using his identical brand new alnico pickups before and was never quite happy although they were decent sounding strat pickups, just a little cold and maybe too clear, not what you would call warm at all.
Let me tell you that aging the alnico strat pickup to 1957 levels made all the difference in the world. WhenI compared my guitar to my buddies all original 1956 Fender strat, we were both surprised how close they were in sound after installing the aged alnico when compared to the non aged JM Rolph alnico strat pickups I had before. My strat did not have any poly finish and had all the other things like the callaham trem block, bone nut and all the rest of the stuff very similar if not identical to an original 50's strat plus they both had alder bodies and maple necks. Just pointing all this out to say it was a very level playing field for sound quality on both guitars. (Also the wood on my guitar was aged high quality stock from a high end builder so you people even more nit picky than myself can relax.)
If you have been reading this post you know that I am a nit picker and if there wasn't an impressive difference in sound i wold not be waxing about aged alnico. It also goes to say anyone who owns an investment grade all original quality guitar such as 1956 strat would probably in most circles be called a nitpicker too and not easily impressed. So moral of the story is aged alnico is not necessarily bad and I would make an educated guess that many alnico speakers even after 50 years may not be as accurate as originally designed but still may have a pleasing mellow sound like an aged fine wine and still very usable.
Most of what makes any "vintage" guitar pickup seem more special than any custom wound by god himself type, is the fact that after time, a few windings are a little loose and the thing is slightly microphonic, just not enough to be a problem (yet). Winders can't do this. So you'll never get quite all the way there that way.
Also FYI, ash bodies continued after mid '56, but on blonde finished guitars only.
Ahhh..! I knew there would be a vintage guitar guy to rub in my mistake about fender guitar wood in the 50's..LOL.
Ok now on to alnico magnet discussion.
I am not sure how much more scientific you could get showing that most major difference in sound we heard in the two different strat pickups was attributed to different magnet strengths of the alnico magnets.
My buddies 56' Strat has hardly any more microphonics on any of its pickups that either of the new pickups. Even if it did, we could detect
no major differences between old and new pickups.
1. Both new strat pickups were scatter wound by the same winder.
2. Both new strat pickups used the same wire on windings and leads
3. Both new strat pickups used the same carbord ends
4. Both new strat pickups used the same alnico pole pieces except for charge level.
The only difference was the magnet strength and the pickups with the weaker 1957 alnico magnet strength was so close that two of the most nitpicking audio a holes on the planet could scarcely detect a difference that was meaningful between the new Rolph strat pickup and a real 50's one it was copying.
Did I miss something here?
Anyway all this talk about guitar magnet strength still does translate to alnico hi fi speakers because yes they do loose power over time but I would guess it is not necessarily the end of the world most of the time if you don't recharge your very old alnico drivers unless the magnets are super weak. May actually be a nice mellow clear sound to your vintage alnico that is quite pleasant.
The same audio a holes may not be able to tell the difference between a 57 strat pu and a recent Korean ceramic strat pu. LOL
Which says a lot about what can be done today for pennies.
Your friend's strat may not be microphonic at all, but the phenomenon exists, period.
I can see why professional writers get paid well. There is definitely a fine art to making something understandable without being long winded and loosing people. I will attempt to be more clear and to the point with short numbered points.
1.I 100% agree it is a fact that microphonic guitar pickups exist, it is a well established fact, I never disputed that, so what the heck? I guess I guess my story was not clear that the strength of the alnico was just much larger a factor for sound differences than microphonics in our particular test.
2.I 100% disagree that a ceramic magnet "anything" be it guitar pickup, speaker driver, microphone, etc. can sound the same as an alnico. The magnetic field responds very differently and no amount of shorting rings or other tricks can ever change this in my experience so far.
3.I know you are joking that that my a hole buddy and I are completely clueless but c'mon do you seriously believe even a non guitar player could not hear the night and day difference between an original 1950's strat and low cost Korean model with a thick tone sucking poly finish, non-responsive too bright crappy ceramic pickups? Maybe you do, people on this planet believe seem to believe all kinds of crazy things I have found. Guess my buddy should sell his real 56' strat before people find out that the low end Korean strats sound just as good? LOL..!
Correction both strats are ash, sorry if I didn't correct myself , I would just bet some strat nitpickers would at some time point out ash ended in the 6th week of the 13th month on the eve of Leo's birthday during a full moon in 1956...blah blah...LOL...!!! Even though mine is a 57 replica I wanted it to be identical wood to my buddies 1956 when I built mine, love the sound of ash...and the light weight if you find the right piece.
Ok back to hifi talk.
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