Hi,
Just to share. I always have seen back extra magnet, and discouraging discussion about it. So i tryed something a bit different.
Measured this speaker Sica 12s2.5cs a lot of time, with a disapointing high qts of around 0,38-0,40 for a TH. Just tryed something today, and it worked like a charm. Re-mesured with 10 neo magnet around magnet, qts lowered to 0,33-0,35. Magnet off, get again 0,39...
Measured from 1to 9 Vrms for the test.
I'll need more magnets ^^
Just to share. I always have seen back extra magnet, and discouraging discussion about it. So i tryed something a bit different.
Measured this speaker Sica 12s2.5cs a lot of time, with a disapointing high qts of around 0,38-0,40 for a TH. Just tryed something today, and it worked like a charm. Re-mesured with 10 neo magnet around magnet, qts lowered to 0,33-0,35. Magnet off, get again 0,39...
Measured from 1to 9 Vrms for the test.
I'll need more magnets ^^
Attachments
Pretty unique way there of increasing BL.
I'm wondering if there's any risk of any unwanted side-effects..
I'm wondering if there's any risk of any unwanted side-effects..
Sorry, I just measured qes/qms/qts/fs with Brian's website excel sheet/method. No changes here. Didn't do sealed measurement for VAS/mms/cms, nor impedance measurement for the moment. I measured it with the added weight method before, but result were very variable so i kept means values, wich weren't really far from datasheet. I'll have to built sealed measurement box later for fine measurements, but i don't expect a lot of changes on other parameters due to added magnets, or maybe with impedance (?).
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Hi papasteack,
Very cool experiment. Hope you can share the sealed box measurements when you get to that.
Regards,
Very cool experiment. Hope you can share the sealed box measurements when you get to that.
Regards,
Mesured a 1Vrms with some 10 resistor (in serie/parrallel) of 0,1% precision, and with a laboratory scope, speaker suspension seems to have harderned a bit even with burning (seems far from beeing linear with level...), fs=36hz VAS=73 liters (got arround 100 l with added mass before), qms=4,9, qes=0,28, Re=6,25ohm.
You perhaps should pay a little attention to the thermal design of your loudspeaker motor 😉
To be simple : the more you raise the Bl, the more the motor is powerful, the more it heats.
To be simple : the more you raise the Bl, the more the motor is powerful, the more it heats.
With a 9Vrms max in free air, even at 10hz i'm far from those concern. And moreover the final QTS is just the orginal datasheet value (see first post).
It's not about getting more powerful motor, but just to compensate for magnetic field loose (does not seem a voicoil problem, same resistance).
It's not about getting more powerful motor, but just to compensate for magnetic field loose (does not seem a voicoil problem, same resistance).
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You really don't want to look at the datasheet linked in first post, so see below. I explained it in first post.
Factory datasheet QTS is 0,27 (qes of 0,27)...this speaker is built normally with a QTS of 0,27.
It loose some magnetic field for some reason, OR factory magnetizing was really approximative.
Real driver model i got without any tweak got around 0,39 qts. With a lot of neo magnet, it came back to 0,27.
Factory datasheet QTS is 0,27 (qes of 0,27)...this speaker is built normally with a QTS of 0,27.
It loose some magnetic field for some reason, OR factory magnetizing was really approximative.
Real driver model i got without any tweak got around 0,39 qts. With a lot of neo magnet, it came back to 0,27.
Attachments
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Just to add, efficiency is more about cabinet design. About heat, it's like any resistor. The more power you put in, the more heat you get, even with low power motor. I don't plan to let it to 0,27. It's probably too low for what i need, it's more a experiment than a definitive tweak. The 4th bandpass cabinet i plan for is is very sensitive to driver parameters. This long throw speaker was choosen for headroom, price, and it low loose accordion surround. With bandpass efficiency, it sims at xmax for 75wmrs around 108db 35-160hz +/-3db. The neo tweak is just one of the funny way to tune the final cabinet. I'm only playing ^^
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Sorry, i'm lazy !
Why don't you ask the manufactrer ?
In my head... heat could be an issue if you raise the magnetic field of the gap over the manufacturer specifications, a coil is a resistor only in DC.
Because i bought it around 5 years ago, and wanted to play ! Experimenting is funny !
But here, i only make it back to original spec. And as said, i will put it very low power in ! Need only 20wrms for 101db (hornresp/akabak sim), more than enough at home to just start stimulating home resonnances.
Are you sure?
Heat comes from I²R
I comes from the drive voltage divided by the speaker impedance. That does not change.
R comes from the voice coil resistance. That does not change.
The result is that the heat does not change.
If the speaker impedance went down as a result of this modification then more current would flow and there would be more heat.
Do you have evidence that this modification reduced the speaker impedance?
Ah... high impeadance (to the air) coupling is the key of extremely low power consumptions !
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