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Vox MINI3 - Replacing Speaker to start The Best-Ever Street Sound Project

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paulgabor9:
Hi Everyone,

I'm new in these hallowed halls and learning the rites, so have mercy...

In the age of "The Club Goes to the Street" I decided to build (assemble) the World's Greatest Street Sound System - under $ 100, weight 11 lbs., battery-run, pretty and disguisable.  I might need some advice... I'm a musician; I guess breadboards are for toast, no?

To a test I'd like to start with replacing the speaker in my recent issue Vox MINI2, 3Watt street amp. Also, take the whole thing out of it's cute, "boutique" enclosure. Then progress will follow to yield the above superlative.

I've learned (here) not to mess lightheartedly with that speaker-swap in this amp, so it still works. But the sound it does is not what I want. If possible I'd like to test it with 2 x 4" (5)", 90-SPL Visaton speakers - or better. Can this be done, and if yes, why not? (I understand Ohms, but there's more involved here).

Any advice pertaining to this and, consequently, to the Miracle Mini Monster System that will quickly follow is greatly appreciated.

Thanks

Paul
 

joecool85:

--- Quote from: paulgabor9 on September 04, 2020, 01:27:55 AM ---Hi Everyone,

I'm new in these hallowed halls and learning the rites, so have mercy...

In the age of "The Club Goes to the Street" I decided to build (assemble) the World's Greatest Street Sound System - under $ 100, weight 11 lbs., battery-run, pretty and disguisable.  I might need some advice... I'm a musician; I guess breadboards are for toast, no?

To a test I'd like to start with replacing the speaker in my recent issue Vox MINI2, 3Watt street amp. Also, take the whole thing out of it's cute, "boutique" enclosure. Then progress will follow to yield the above superlative.

I've learned (here) not to mess lightheartedly with that speaker-swap in this amp, so it still works. But the sound it does is not what I want. If possible I'd like to test it with 2 x 4" (5)", 90-SPL Visaton speakers - or better. Can this be done, and if yes, why not? (I understand Ohms, but there's more involved here).

Any advice pertaining to this and, consequently, to the Miracle Mini Monster System that will quickly follow is greatly appreciated.

Thanks

Paul

--- End quote ---

There really isn't more to it than ohms as far as what is safe to connect to the amp.  I'm not sure what it has stock, but assuming 8 ohm (please check this), then you could use two 4 ohm speakers in series, or two 16 ohm in parallel.  If you are trying for more volume, I recommend at least 93 db/watt SPL, but ideally 96 or greater.  Is there a reason for only going with 4 or 5" speakers?  This keeps you pretty limited.  Once you get to 8", things start to open up substantially for great SPL as well as sound quality across the frequency spectrum.

Good luck and welcome!

paulgabor9:
Thanks joecool,

(I got stuck in progress…)

My concern about the speaker-swap came from an exchange here (although some years ago) that the Vox Mini3 is (was?) peculiar about it and would fry the preamp if particular care wasn’t given (like, the ground was not really a ground, etc.) Is this still a problem with the new issue of Mini3-G2?

Other concern – widely shared and confusing – WHY, oh Why can’t be Lithium batteries used? The dire warning on the Mini states “use only alkaline AA batteries”. Will it go "pooof" if I use a Lithium battery, output almost exactly matching that of the Mini’s switching power’s? My Lithium cell is 12v-3A (nominal) center positive, the Mini is 12v-1A (nominal?).
Is the pack of 6 x 1.5v AA (9 volts) better? I produce seemingly unending heaps of dead AAs week after week…
In general, perhaps a modern, universal battery powering system should be developed and employed (and it appears that the Lithiums is the way) instead of the clumsy, inefficient and expensive 4-6-8 x AA alkalines?
Thanks,
Paul Gabor

joecool85:

--- Quote from: paulgabor9 on October 19, 2020, 10:45:50 PM ---Thanks joecool,

(I got stuck in progress…)

My concern about the speaker-swap came from an exchange here (although some years ago) that the Vox Mini3 is (was?) peculiar about it and would fry the preamp if particular care wasn’t given (like, the ground was not really a ground, etc.) Is this still a problem with the new issue of Mini3-G2?

Other concern – widely shared and confusing – WHY, oh Why can’t be Lithium batteries used? The dire warning on the Mini states “use only alkaline AA batteries”. Will it go "pooof" if I use a Lithium battery, output almost exactly matching that of the Mini’s switching power’s? My Lithium cell is 12v-3A (nominal) center positive, the Mini is 12v-1A (nominal?).
Is the pack of 6 x 1.5v AA (9 volts) better? I produce seemingly unending heaps of dead AAs week after week…
In general, perhaps a modern, universal battery powering system should be developed and employed (and it appears that the Lithiums is the way) instead of the clumsy, inefficient and expensive 4-6-8 x AA alkalines?
Thanks,
Paul Gabor

--- End quote ---

It depends on the voltage of your lithium ion cell.  Normally they are 3.7v/cell, bringing it to 11.1v or 14.8v to be on either side of "12v."  If it is 11.1v, then that's fine.  If it is 14.8v, it may or may not be fine.  I would say check the voltage of your power adapter - if it is higher than or the same as your charged li-ion pack, go ahead and hook it up to your 12v input.

Either way, without looking at the inside to trace circuit, I would not recommend connecting anything higher voltage than 9v to the battery hookups as this is what it was designed for.  Higher voltage will need to go through the 12v input.

11.1 or 14.8

dmeek:
This is the amplifier chip used in the Mini3. Note the physical size - 1.5mm square!

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