Need to remove speaker shielding

I'm trying to mount some 8ohm speakers in my doors, (with the way I'm wiring things I needed some 8ohm spekers) but since they're more of a home audio speaker they have big magnetic shields on the magnets. Anyone know of a good way to get them off without damaging the speakers so I have a little more room? I think I may have to mount the speakers on the back of the door panel instead of dropping them into the holes for the sake of mounting flush, and getting the speakers in place inside the door is not going well so far.

The chances of you getting them off, without damaging the speaker is pretty slim. The epoxy that is used to attach the shielding cup is usually the same epoxy used to assemble the motor structure... What I am saying is this: JUST as strong, and just as solvent resistant.

You will have much better luck actually using different speakers. Just don't use shielded versions.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

what way are you wiring in such that you need 8ohm speakers?

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Doesn't matter, really... That's not why he came here.

I have 8 ohm speakers in my car, and are you gonna grill me, too? ROFL

Take that in the spirit in which it is intended, please.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

I'm putting a tweeter and woofer in each door. I also have a pair of custom fourth order crossovers built for them, so they need to be wired in parallel. So in order to not fry my HU, they both need to be about 8ohms in order to give the HU the 4ohm load it's looking for. The crossovers also have zobels in them made for the woofers, so I'd really rather not change speakers.

Either way, I managed to get the magnets off. Haemphyst, you were right. Very strong epoxy. The magnets chip off before they break cleanly off. The motor came detached on one of the woofers in the process, but I centered everything back up so the coil moves freely without binding up, and as long as the motor holds up, I'm not going to worry about it.

I'm interested in having a look at that crossover schematic.  Can you find a way to post that info up here?

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Sad, little man wrote:

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I'm putting a tweeter and woofer in each door. I also have a pair of custom fourth order crossovers built for them, so they need to be wired in parallel. So in order to not fry my HU, they both need to be about 8ohms in order to give the HU the 4ohm load it's looking for. The crossovers also have zobels in them made for the woofers, so I'd really rather not change speakers.

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If I am understanding completely what you are saying, that's incorrect. With the crossover in place, the HU will be seeing 8 ohms. The crossover presents to the amplifier (basically) 8 ohms ABOVE the crossover point, in parallel with (effectively) an infinitely high impedance below the crossover point.

This same electrical phenomenon with the woofer section, only in reverse.

Your HU will be seeing an 8 ohm load.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Sure, here are the crossover schematics.

Highpass
Lowpass

I can't take credit for these though. Someone who goes by Nizidramanii'yt on the miata.net forums designed this whole system for his car, and I'm duplicating it. I did make those schematics though so I could get a better picture of how they were going to be wired. I guess they're technically two crossovers, but I have them wired up in one box with input and output wires. All of the capacitors are just in parallel to match the values I was given with what was avalible, they could be made with fewer capacitors if you found the right values. And the resistors on the high pass side are just there to even out the tweeter and woofer volumes. There are two in parallel so they don't blow. I don't know about the impedence issue. I don't know enough about it to know if it would be four or eight ohms wired up like this. I can't test it with a multimeter since those capacitors on the high pass side screw up the true impedence. If you test the highpass side from the crossover input it's something ridiculous like 1 mega ohm, which definitely isn't what the HU truly sees.

Above the crossover point, the amplifier (whether external or deck) will see about 7.5 ohms, and below the crossover point the amplifier will see a little over 8 ohms. The reason the tweeter is reading 1M is because capacitors block DC (and they are wired in series, for purposes of testing thus effectively blocking DC), which is what the VOM uses for reading Ohms.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

I guess I still don't get it. You have two 8ohm speakers per channel. One woofer, one tweeter. Each of them go through their own filters totally electrically separate from each other in the crossover. The only time their circuits meet is at the amplifier (HU) where they're wired in parallel. How is this different from two 8ohm speakers in parallel? Are you saying somehow the filters change their impedance? Maybe professionally built crossovers work differently, but my highpass and lowpass are totally separate, so I don't see how it comes out to 8ohms total load. I'm not saying you're wrong, I'm just saying I don't understand how it works. I know that if I test the lowpass circuit's resistance it's about 8ohms on its own. I can't really test the highpass circuit like we said, but I can only assume with the 6ohm tweeter and the 1.5 ohm resistance in the crossover it comes out to about 7.5ohms total. So I have a circuit I know from testing is 8ohms, and one that I assume is in the 8ohm ballpark, so parallel those, and....?

Man, talk about a hack job.  I would NEVER recommend removing the bucking magnets from shielded speakers and then expecting them to work properly.... but to each his own I guess.

The amplifier is always loaded with the effective impedance of only ONE speaker if the crossovers are properly designed.  That is the function of the crossovers.  This is a gross over-simplification, but think of a crossover as "connecting" only the speaker that is appropriate for the instantaneous frequency of the signal at every given moment.

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Haem is correct. Let me take a crack at this. Let's try using an analogy. We'll assume you're high pass and low pass cutoff points are both 3,000 hertz. The woofer plays all frequencies below 3 kHz, and the tweeter plays all frequencies above 3 kHz. This is dictated by the crossover.

The filters in the crossover wired to the woofer create an "infinite" impedance above 3 kHz since those frequencies are effectively blocked. The filters wired to the tweeter create an "infinite" impedance below 3KHz since those frequencies are effectively blocked. This means the amp only "sees" the woofer (8 ohms) below 3KHz, and only "sees" the tweeter (8 ohms) above 3KHz.

Since the seperate drivers never play the same frequency, there only appears to be one 8 ohm driver to the amplifier, even though they're playing at the same time. This is not a technically accurate post, but it should give you a basic understanding of why this works.

For a better understanding of crossovers, read over this: https://www.the12volt.com/caraudio/cross.asp.

Dave, I see you beat me to it.

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My ex once told me I have a perfect face for radio.

But your explanation is more complete geep. 

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Ok, thanks, I understand now. I wasn't thinking about the frequency cutoffs. Well, I guess 8ohms it is then. As far as the shielding, I know it's not the best idea, but I really needed the speakers to fit inside the door. I'm not hacking my car to pieces to fit a set of speakers. I'd rather hack up a pair of $60 speakers to fit the car.

Consider cutting some spacers out of wood to bring the speakers farther away from the door metal. Just ensure you've got enough clearance away from the door panel.

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My ex once told me I have a perfect face for radio.

Sad, little man wrote:

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Sure, here are the crossover schematics.

Highpass
Lowpass

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A good crossover design is one that is 1) appropriate for the system it is designed for, and 2) simpllified, as much as possible, to that degree.  Neither of which applies with this one.  The designer should ask himself a series of questions after the initial design to find out how much of an overhaul is needed.  With this one, I would ask, "Why can't I achieve proper results with a 2nd order crossover?  Are the drivers I'm using the best choices to use?  Could a replacement woofer be the key to eliminate the added impedance compensation network?  Can I find satisfactory results by using just one component of an available value rather than two or three extra components wired together to achieve the same result?....."

But you've already built them, so...  Watch your wiring polarity at the tweeter.  The diagram doesn't show it, but the drivers should probably be in opposing polarity in this network.  Usually, the tweeter is reversed, with the neg terminal connected to the pos side.

You will likely have woofer damage due to the removal of the shielding.  For replacement woofers, look for the same model woofer without the shield for closest results.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Why opposing polarity, wouldn't they be out of phase? Also, using spacers wouldn't work. That was the original plan, but the door panels won't fit back on with the speakers sticking out from the door.

No, sorry, that shouldn't apply with a 4th order.  The phase shift should be 360 degrees, which equals 0 degree phase shift, thus no reversing of a driver.

https://www.apicsllc.com/apics/Misc/filter2.html#fourth

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Others on this forum have had success spacing the window track back a little for extra clearance. I probably wouldn't try more than about a 1/2 inch or so- that way the window should still function reasonably well.

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My ex once told me I have a perfect face for radio.

So it turns out that the tweeters I just installed are just too loud in relation to the mids. I went ahead and ordered one of these variable L-pads that I plan on wiring into the tweeter circuits so I can have control of the tweeter volume independent of the mids right on the dash. As I understand it, for each channel, one of the three terminals is for the speaker signal positive, one is for the tweeter's positive wire (this terminal is hooked to the wiper inside that slides across the coil and varies resistance)and the third terminal just couples the tweeter negative wire with the negative wire from the source. Is that about right? And if so, what is the point of the negative terminal? Couldn't you just bypass the whole thing on the negative side?