Moving a subwoofer cone for display

[Webby]

Hi all,

I am in the situation where I need a circuit built in 3 days time that will
move a subwoofer full cone excursion slowly to demonstrate the subwoofer. The
subwoofer will be enclosed in a soundproof seethrough container.


I figure the circuit will need to supply a sine wave of approx 1hz to be able
to see the cone move. What would be the best and fastest way of completing
this any advice welcomed.

 

[Phil Allison]

Hi all,

I am in the situation where I need a circuit built in 3 days time that will
move a subwoofer full cone excursion slowly to demonstrate the subwoofer. The
subwoofer will be enclosed in a soundproof seethrough container.


I figure the circuit will need to supply a sine wave of approx 1hz to be able
to see the cone move. What would be the best and fastest way of completing
this any advice welcomed.

** A 1 Hz sine wave (or maybe triangle) generator fed into almost any
audio amplifier.

A function gen will do as a signal source.




.......... Phil

 

[Matthew Palmer]

Webby is of the opinion:

I figure the circuit will need to supply a sine wave of approx 1hz to be
able to see the cone move. What would be the best and fastest way of
completing this any advice welcomed.

Sine waves are arse-pains to generate. The simplest way would be to
generate a 1Hz square wave then filter off the harmonics.

A different approach might be to generate a triangle wave instead - that'll
do a good job of demonstrating the speaker movement, and is a segment of
urine to make - square wave through an op-amp integrator. No doubt there'll
be a million-and-one circuits to do that on the web (hell, even a 555 can be
made to do the job).

 

[Phil Allison]

[email protected]:



I realise I can generate that sort of signal with a function gen but I was
hoping for something a tad smaller I am not sure we can get hold of one in such
a short amount of time either.

** Use a 555 to get a 1 Hz square wave and RC filter to output so you
get a triangle.

More stages of such filtering will produce a sine wave.




........... Phil

 

[Webby]

** Use a 555 to get a 1 Hz square wave and RC filter to output so you
get a triangle.

More stages of such filtering will produce a sine wave.




.......... Phil

Ok now no problem, will I need a preamp of some kind on the 555 output to
make it compatible with the subamp input ? I guess I need to get it down to
line level.

 

[Phil Allison]

Ok now no problem, will I need a preamp of some kind on the 555 output to
make it compatible with the subamp input ?

** Nope. A 555 will easily output a 12 volt peak to peak square wave -
after an RC filter you will have a 2 or 3 volt rms triangle wave. At ***1
Hz*** you need ***verrrrry*** little power to push a woofer to its
excursion limit - 2 -3 watts at most.




........... Phil

 

[Webby]

** Nope. A 555 will easily output a 12 volt peak to peak square
wave -
after an RC filter you will have a 2 or 3 volt rms triangle wave. At
***1 Hz*** you need ***verrrrry*** little power to push a woofer to its
excursion limit - 2 -3 watts at most.




.......... Phil

Ok thanks for all the help I wasnt sure if a 555 would oscillate at 1hz

 

[The real Andy]

** 100 k ohms plus 10 uF will get you close to 1 Hz.

My home brew enlarger exposure timer gets to 5 minutes per cycle
using the humble beast.

Sorry to jump in on a topic that I have no idea about, but wouldn't such a
low frequency signal driving a speaker to its maximum exursion be very bad
for the voice coil in terms of heat dissipation?

 

[Phil Allison]

Sorry to jump in on a topic that I have no idea about,

** Hey, why apologise Andy ??

That is nothing new for you at all.

but wouldn't such a low frequency signal driving a speaker to its maximum exursion be very bad
for the voice coil in terms of heat dissipation?

** So 2 or 3 watts is destruction plus ???????





........... Phil

 

[The real Andy]

** Hey, why apologise Andy ??

That is nothing new for you at all.

How does "GET FUCKED" sound??

maximum
exursion be very bad

** So 2 or 3 watts is destruction plus ???????

I was thinking that he was talking about those big-ass subs. I had no idea
you could get them to move with that little amount of power.

 

[Phil Allison]

I was thinking that he was talking about those big-ass subs. I had no idea
you could get them to move with that little amount of power.

** Usually 3 or 4 volts DC will push a low resonance woofer close to
max excursion.

Try it.



.......... Phil

 

[Webby]

I was thinking that he was talking about those big-ass subs. I had no
idea you could get them to move with that little amount of power.

Actually that is a good question, how will the signal affect the voice
coil. I would hate to fry it. Would be VERY expensive to replace. So what
do I need to watch. Dont forget the signal will be making the cone go to
full excursion once a second for 20 Hours at a time. Will need to make
sure the sub amp is turned down when powered up.

Ok I have got a 1.1sec (~1HZ) pulse out of the 555 it is 13.8V rail.How do
I shape that pulse to a triangle wave (needs to be a triangle because I
want a linear Leading and trailing edge so that the cone doesn't pop up or
down but moves smoothly) with a p-p value that will be within line level
specs to feed into the subamp?

 

[Phil Allison]

Actually that is a good question,

** Huh - so now a complete moron knows what the issues are ???????



( snip anal shite)

Ok I have got a 1.1sec (~1HZ) pulse out of the 555 it is 13.8V rail.How do
I shape that pulse to a triangle wave (needs to be a triangle because I
want a linear Leading and trailing edge so that the cone doesn't pop up or
down but moves smoothly) with a p-p value that will be within line level
specs to feed into the subamp?

** Are you so dumb you do not know what an RC network is ??????

Duuuuuhhhh - one R plus one C !!!!!!


Forget line level you jerk.








............ Phil

 

[Webby]

** Are you so dumb you do not know what an RC network is ??????

Duuuuuhhhh - one R plus one C !!!!!!


Forget line level you jerk.



........... Phil

Wow you really need to chill out a bit.

Thanks for the help, I am so glad I asked for some.

 

[Phil Allison]

Wow you really need to chill out a bit.

** What you need to realise is that you are a total wanker.




......... Phil

 

[Webby]

** What you need to realise is that you are a total wanker.




......... Phil

Haha I thought I would go back through the newsgroup and have a bit of a look
at your history, and guess what. It appears that you are the wanker.

 

[Phil Allison]

Haha I thought I would go back through the newsgroup and have a bit of a look
at your history, and guess what. It appears that you are the wanker.

** Masturbation fantasies of a wanker - he sees what he wants to see.




........... Phil

 

[amstereo - matt2]

NCH Tone generator software, windows PC, 100 Watt amp, set to whatever
freqency, done.
Perfer old amp without low-pass filter on output
http://www.world-voices.com/software/tnsetup.exe

 

[amstereo - matt2]

NCH Tone generator software, windows PC, 100 Watt amp, set to whatever
freqency, done.
Perfer old amp without low-pass filter on output
http://www.world-voices.com/software/tnsetup.exe

~ 1MB (3 min on 56K modem)