what bands does it occur on? or perhaps a better question, which bands is 
the noise the worst on?
You could use a cap to ground from the posative lead of the speaker 
wire...this might attenuate some audio frequencies though.
Shielding is a viable option as well...copper foil around the inside surface 
of the speaker case could help to prevent the rf from getting into the 
speaker coil.
Also, what is happening is that the cheap realistic preamp is picking up rf 
and sending into the speaker at a far higher level than what would occur 
with an non-amplified speaker.
An audio isolation transformer between the radio and speaker might also help 
to get rid of RF on that line.
Try connecting the speaker to a properly regulated and filtered 13.8V power 
supply...in other words, it might be the wallwart that is causing allot of 
your problem.
Back in my CB days, I tried amplified external speakers, and always had RFI 
problems through the speaker even with 4W on AM.
Perhaps a ferrite choke between the preamp and the speaker itself, inside 
the case, might help to get rid of RF before it gets to the speaker coil.
so there you go.  As you know, with RFI, there is seldom one single thing 
that you can do to make it disappear.
But, with enough experimentation, you can usually accomplish the task of 
making the noise go away, or at least, drastically attenuating it.

73
Colin, V A6BKX
----- Original Message ----- 
From: "John Miller" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, May 07, 2012 8:11 AM
Subject: Re: Interesting RFI Problem


>I see that with a lot of cheap computer/similar speakers. Sometimes moving
> them away from the equipment helps, sometimes not, sometimes chokes help,
> sometimes nothing helps, it's just one of those things.
> ----- Original Message ----- 
> From: "Tom Behler" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Monday, May 07, 2012 7:04 AM
> Subject: Interesting RFI Problem
>
>
>> Hi, all.
>>
>> Well, I have an interesting little RFI problem here in the home shack 
>> that
>> I've been scratching my head over lately.
>>
>> At the estate sale I've been talking about, I picked up a Realistic
>> 32-2040
>> amplified speaker.  The speaker either runs on 6 C-cell batteries, or the
>> supplied 9-volt wallwart.
>>
>> The speaker sounds terrific, with excellent quality  audio that I can
>> adjust
>> in terms of tone and volume from the speaker itself.
>>
>> However, when I transmit with my TS590, using my amplifier, I get lots of
>> RFI through the speaker itself.
>>
>> I have tried RF chokes on both the Wallwart power cord, and the phono 
>> plug
>> connection between the Ts590 and the speaker itself, but no joy.
>>
>> I have tried running the speaker just on batteries, but still get the 
>> RFI.
>>
>> Obviously, this particular speaker is more susceptible to RFI than usual,
>> since I don't get the RFI at all when using other speakers such as my
>> Motorola amplified speaker or just a standard external speaker.
>>
>> Does anyone have any suggestions as to what else I might try?
>>
>> I'd love to use the speaker since it sounds so good, but the RFI issue 
>> may
>> make that impractical in the long run.
>>
>> 73 from Tom Behler: KB8TYJ
>