20Hz production cheap?

[JohnB]

Hello experts!

I would like to run a cheap experiment. I will take a 10 or 12" subwoofer
speaker, and wish to make it pulse from 0 - 20 Hz. I would like to do this
relatively cheaply.

Needs:

1) Function generator - would be nice to have a digital display, but not
necessary. I see function generators all over eBay. It seems I can buy
anything that can produce my desired frequency range. (?)

2) Amplifier - I have NO idea what specifications I need here. I just wish
to make the speaker pulse at the low frequencies. I would like a good
pulse, a muddy vibration would not be good. What do I need to look for,
what should my spec. concerns be?

3) Subwoofer - I would like something relatively lightweight that I can
easily hold in my hand. I'm guessing that isn't an issue, as the cheaper
the speaker, the smaller the magnet, and the lighter it is.

4) Connectors - I see function generators tend to have BNC outputs. do I
look for BNC to RCA connectors at Radioshack? How should I connect the
generator to the amp?

Thanks for the advice,

John

[Robert Morein]

Don't do this.
You will throw the voicecoil of the woofer right out of the housing.
There is no way to make a 0 Hz signal. You must have a low frequency cutoff,
and the speaker/enclosure/drive circuitry must designed to handle this
cutoff.

"JohnB" > wrote in message
...
> Hello experts!
>
> I would like to run a cheap experiment. I will take a 10 or 12" subwoofer
> speaker, and wish to make it pulse from 0 - 20 Hz. I would like to do
this
> relatively cheaply.
>
> Needs:
>
> 1) Function generator - would be nice to have a digital display, but not
> necessary. I see function generators all over eBay. It seems I can buy
> anything that can produce my desired frequency range. (?)
>
> 2) Amplifier - I have NO idea what specifications I need here. I just
wish
> to make the speaker pulse at the low frequencies. I would like a good
> pulse, a muddy vibration would not be good. What do I need to look for,
> what should my spec. concerns be?
>
> 3) Subwoofer - I would like something relatively lightweight that I can
> easily hold in my hand. I'm guessing that isn't an issue, as the cheaper
> the speaker, the smaller the magnet, and the lighter it is.
>
> 4) Connectors - I see function generators tend to have BNC outputs. do I
> look for BNC to RCA connectors at Radioshack? How should I connect the
> generator to the amp?
>
> Thanks for the advice,
>
> John

[Arny Krueger]

"JohnB" > wrote in message

> Hello experts!
>
> I would like to run a cheap experiment. I will take a 10
> or 12" subwoofer speaker, and wish to make it pulse from
> 0 - 20 Hz. I would like to do this relatively cheaply.

0 Hz is DC, an impractically low frequency for attempting to
reproduce audio. Think of it as raising the barometric
pressure in the room and keeping it there.

As a practical matter, 3-5 Hz are possible lower limits for
your experiment.

You want to do this experiment in a reasonably small room,
as that makes generating bass easier.

> Needs:
>
> 1) Function generator - would be nice to have a digital
> display, but not necessary. I see function generators
> all over eBay. It seems I can buy anything that can
> produce my desired frequency range. (?)

A low cost option - use the audio interface in your PC to
reproduce digitally-generated test signals.

> 2) Amplifier - I have NO idea what specifications I need
> here. I just wish to make the speaker pulse at the low
> frequencies. I would like a good pulse, a muddy
> vibration would not be good. What do I need to look for,
> what should my spec. concerns be?

You want an amplifier with good subsonic response. Many
common amplifiers are designed to roll-off response below 20
Hz.

> 3) Subwoofer - I would like something relatively
> lightweight that I can easily hold in my hand. I'm
> guessing that isn't an issue, as the cheaper the speaker,
> the smaller the magnet, and the lighter it is.

Lightweight and low bass don't go together. Neither does
cheap.

> 4) Connectors - I see function generators tend to have
> BNC outputs. do I look for BNC to RCA connectors at
> Radioshack?

They have 'em.

> How should I connect the generator to the amp?

If you're really fixed on that function generatgor, use
regular shielded cable. Use a regular audio cable with a
BNC-to-RCA adaptor.

[[email protected]]

JohnB wrote:
> Hello experts!
>
> I would like to run a cheap experiment. I will take a 10 or 12" subwoofer
> speaker, and wish to make it pulse from 0 - 20 Hz. I would like to do this
> relatively cheaply.

I don't know why you'd want to do this, but I'll answer the questions
where I have an answer.

I also suggest you post in:

rec.audio.tech

> Needs:
>
> 1) Function generator - would be nice to have a digital display, but not
> necessary. I see function generators all over eBay. It seems I can buy
> anything that can produce my desired frequency range. (?)
>
> 2) Amplifier - I have NO idea what specifications I need here. I just wish
> to make the speaker pulse at the low frequencies. I would like a good
> pulse, a muddy vibration would not be good. What do I need to look for,
> what should my spec. concerns be?
>
> 3) Subwoofer - I would like something relatively lightweight that I can
> easily hold in my hand. I'm guessing that isn't an issue, as the cheaper
> the speaker, the smaller the magnet, and the lighter it is.

For the amp and the subwoofer speaker driver, you could just buy a
powered 10" or 12" sub from eBay.com or elsewhere. Then you could take
the subwoofer speaker driver and hold that in your hand.

> 4) Connectors - I see function generators tend to have BNC outputs. do I
> look for BNC to RCA connectors at Radioshack?

Try: www.RadioShack.com

> How should I connect the
> generator to the amp?
>
> Thanks for the advice,
>
> John

[[email protected]]

"JohnB" > wrote in message
...
> Hello experts!
>
> I would like to run a cheap experiment. I will take a 10 or 12" subwoofer
> speaker, and wish to make it pulse from 0 - 20 Hz. I would like to do
> this
> relatively cheaply.
>

0 Hz is not going to be possible, try for 5 Hz.

> Needs:
>
> 1) Function generator - would be nice to have a digital display, but not
> necessary. I see function generators all over eBay. It seems I can buy
> anything that can produce my desired frequency range. (?)
>
You don't need to buy anything like that, you can use free test tone
generators that are downloadable. Try search for test tones.


> 2) Amplifier - I have NO idea what specifications I need here. I just
> wish
> to make the speaker pulse at the low frequencies. I would like a good
> pulse, a muddy vibration would not be good. What do I need to look for,
> what should my spec. concerns be?
>
Something that doesn't roll off as many amps are designed to do.
A price point would be helpful to better advise you.

> 3) Subwoofer - I would like something relatively lightweight that I can
> easily hold in my hand.

I guess that depend on how strong you are, but as a rule, low bass and
lightweight do not go together. The most affordable 12" woofer I know of
capable of 20 Hz or lower is the Adire Audio Shiva @ $125.00 IIRC.
www.adireaudio.com


I'm guessing that isn't an issue, as the cheaper
> the speaker, the smaller the magnet, and the lighter it is.
>

But if it doesn't have enough excursion, it won't get to the lower
frequencies.
I don't think you'll find a woofer capable of the very low bass that has a
magnet less than 40 oz. Typically a decent low bass driver will weigh 10lb.
or more.

> 4) Connectors - I see function generators tend to have BNC outputs. do I
> look for BNC to RCA connectors at Radioshack? How should I connect the
> generator to the amp?
>
Use a regular audio cable with a BNC-to-RCA adaptor, these are available at
Rat Shack and elsewhere. You should use shielded cable.



> Thanks for the advice,
>
> John