Newbie here....treble and bass control for portable speakers

[elfa]

I'm pulling my hair out trying to come up with a simple circuit that can be
placed between a speaker and its amplifier to control treble and bass.

My project is to use a portable, battery powered speaker system (like PC
speakers or the portable battery powered types), replace the small speaker with
a larger one, and add treble and bass controls between the two. I've already
got a 6 volt amplifier (4 C size batteries) attached to a 6 inch speaker (works
fine). NOW....I want to add a simple treble and bass system between the two.

I'm hearing impaired and this would help me listen to portable radios a lot
better.

any suggestions would be appreciated.

elfa

 

[YD]

I'm pulling my hair out trying to come up with a simple circuit that can be
placed between a speaker and its amplifier to control treble and bass.

My project is to use a portable, battery powered speaker system (like PC
speakers or the portable battery powered types), replace the small speaker with
a larger one, and add treble and bass controls between the two. I've already
got a 6 volt amplifier (4 C size batteries) attached to a 6 inch speaker (works
fine). NOW....I want to add a simple treble and bass system between the two.

I'm hearing impaired and this would help me listen to portable radios a lot
better.

any suggestions would be appreciated.

elfa

I'm afraid tone controls in the speaker path wouldn't be a very hot
idea. All such controls are selective (sort of) attenuators so you'd
end up with quite some volume loss. The low impedances would make them
bulky due to the largish caps needed. The best you can do is to open
up the amplifier and insert a Baxandall or James type circuit
somewhere in the signal path. If that's not possible try inserting it
in a separate box between the radio and the amp. Try
http://www.discovercircuits.com, I think there's something suitable
there.

- YD.

 

[Rich Grise]

The tone controls go on the input side of the amp. I.e., plug
your tone control box into the source, and the amp into the
tone control box.

A quick http://www.yahoo.com search on "tone control circuit"
came up with about 165,000 hits.

Good Luck!
Rich

 

[N. Thornton]

Hi Elfa.

Tone controls are not normally put between speaker and amp these days,
tho it is certainly possible and practical in some cases.

It would help a lot if we knew specifically what you want to achive:
treble boost, treble cut, bass boost, bass cut, or something else.
Some of these are very easy to implement, some can be done as you
suggest no problem.

If you want the full bass and treble boost and cut, then really you'll
need an active circuit attached to the amp's input.

Regards, NT

 

[elfa]

Hi Elfa.

Tone controls are not normally put between speaker and amp these days,
tho it is certainly possible and practical in some cases.

It would help a lot if we knew specifically what you want to achive:
treble boost, treble cut, bass boost, bass cut, or something else.
Some of these are very easy to implement, some can be done as you
suggest no problem.

If you want the full bass and treble boost and cut, then really you'll
need an active circuit attached to the amp's input.

Regards, NT

The little speaker system I have jury rigged has a 6 inch 'woofer' and 1 3/8
tweeter. I'm not sure what you mean by bass boost and cut. All I'm trying to do
is create a speaker system that's as good as my Superadio 2 which has treble and
bass with 6 and 1 3/8 speakers. I can plug my little system into any palm sized
radio and get better sound but not be able to adjust it like I can with my
Superadio.

That's not a very good answer, but the best way I can describe it. I'm not an
audiophile....just hard of hearing and trying to listen to the news on a pocket
shortwave radio that has a speaker that's too small to produce decent sound.

Another poster in another group suggested I try the website below:

http://amps.zugster.net/articles/tonestacks/

I was thinking of the 2 pot Baxendall, midway down the page. I would put it
between the amp and the speakers.

Any thoughts on it?

elfa

 

[Rich Grise]

Ah!

That's not a tone control, it's a crossover network. You want the
high freq's (treble) to go mainly to the small speaker (the tweeter)
and the low freq's (bass) to go mainly to the larger one, the woofer.

That's an entirely different animal, and forgive us for shoving all the
wrong solutions at you when it's just a difference in terminology.

Please don't feel badly about using a different term, you couldn't be
expected to know all of our technical jargon!

A http://www.google.com search on "crossover network" gives more
information than you probably wanted to know - but now that we know
the right question, I'm sure someone will give you the right answer
within minutes. Us technogeeks sit here champing at the bit waiting
for some newby to ask a question so we can pounce. =:O

Good Luck!
Rich

 

[elfa]

Well...if it works, it works. Doesn't a crossover network control tone by
controlling the amount of freqs going to a speaker? I'd try to make it but I'm
missing the some parts.

BTW, based on what I've told you so far, would it work by placing it between the
battery powered amp and speakers?

elfa

 

[N. Thornton]

The little speaker system I have jury rigged has a 6 inch 'woofer' and 1 3/8
tweeter. I'm not sure what you mean by bass boost and cut. All I'm trying to do
is create a speaker system that's as good as my Superadio 2 which has treble and
bass with 6 and 1 3/8 speakers. I can plug my little system into any palm sized
radio and get better sound but not be able to adjust it like I can with my
Superadio.

That's not a very good answer, but the best way I can describe it. I'm not an
audiophile....just hard of hearing and trying to listen to the news on a pocket
shortwave radio that has a speaker that's too small to produce decent sound.

Another poster in another group suggested I try the website below:

http://amps.zugster.net/articles/tonestacks/

I was thinking of the 2 pot Baxendall, midway down the page. I would put it
between the amp and the speakers.

Any thoughts on it?

elfa

I dont think I can help if I dont know what you want. I suggest
playing with a hifi and finding out.

If what you want is a crossover instead, all you need for that is a
2uF capacitor in series with the tweeter.


Regards, NT

 

[John Woodgate]

I read in sci.electronics.design that elfa <[email protected]>

I was thinking of the 2 pot Baxendall, midway down the page. I would
put it between the amp and the speakers.

You can't put that sort of circuit between the amplifier and the
loudspeaker. I could explain why, but I think you'd have a very hard job
understanding the explanation.

That sort of circuit has to go BEFORE the power amplifier that drives
the loudspeaker.

 

[Rich Grise]

Yes, you have the concept pretty much right, but the terminology seems
to be escaping you. The way the terms are usually used amongst the
electronics crowd, "Controlling the tone" means to change how the
overall sound sounds to your ear, regardless of how the components
of the sound get sent from amp to ear by whatever arrangement of
speakers. We don't usually think of a crossover network doing any
"controlling"; simply separating parts of the signal, so that
the higher ones simply go to the smaller speaker, and so on.

In a way, it's like as if you took your signal source, sent it
to a "Y" connector, which goes to 2 amps - one with a treble boost
and the other with a bass boost, but the settings are nailed in
place and can't be changed. Typically, we'd use the term "control"
if those settings were adjustable in real-time. I.e. "control"
implies a knob of some kind.

Ah! I've got it. A control is an active device; a crossover network
is just a splitter, a passive device. Think of the splitter/combiner
they use to get VHF and UHF TV signals onto the same cable, then
separate them at the TV end.

And that's what you want to do, right? Cause the treble to go more
to the small speaker, and the bass to go more to the big one? That's
the standard way of doing it, anyway.

As far as getting parts, they're really common - I'd be surprised
if your local RS equivalent parts store doesn't have something
you could use - you just need to figure out what values to use
with your particular speakers.

Post as much information as you can get your paws on about your
speakers and amp, and if somebody hasn't designed you one in a
day or so, I will. By that time, and with the resources you
can get with a google search, you might have even figured it out
yourself.

Good luck!
Rich

 

[elfa]

Yes, you have the concept pretty much right, but the terminology seems
to be escaping you. The way the terms are usually used amongst the
electronics crowd, "Controlling the tone" means to change how the
overall sound sounds to your ear, regardless of how the components
of the sound get sent from amp to ear by whatever arrangement of
speakers. We don't usually think of a crossover network doing any
"controlling"; simply separating parts of the signal, so that
the higher ones simply go to the smaller speaker, and so on.

In a way, it's like as if you took your signal source, sent it
to a "Y" connector, which goes to 2 amps - one with a treble boost
and the other with a bass boost, but the settings are nailed in
place and can't be changed. Typically, we'd use the term "control"
if those settings were adjustable in real-time. I.e. "control"
implies a knob of some kind.

Ah! I've got it. A control is an active device; a crossover network
is just a splitter, a passive device. Think of the splitter/combiner
they use to get VHF and UHF TV signals onto the same cable, then
separate them at the TV end.

And that's what you want to do, right? Cause the treble to go more
to the small speaker, and the bass to go more to the big one? That's
the standard way of doing it, anyway.

As far as getting parts, they're really common - I'd be surprised
if your local RS equivalent parts store doesn't have something
you could use - you just need to figure out what values to use
with your particular speakers.

Post as much information as you can get your paws on about your
speakers and amp, and if somebody hasn't designed you one in a
day or so, I will. By that time, and with the resources you
can get with a google search, you might have even figured it out
yourself.

Good luck!
Rich

Thanks for your response. The amp is nothing more that a portable amplified
speaker system that you can buy for $20. They usually come with 2 1/2 inch
speakers and a battery compartment for 4 batteries. Some also have a provision
for plugging in an AC/DC adapter. The one I'm using has a 2 1/2 in speaker with
a 1 3/8 tweeter with a capacator connecting the two.

I literally cut the speaker (with amp inside) in half and substituted a 5 1/2 in
speaker for the 2 1/2 (still keeping the 1 3/8 tweeter with cap connection).
When plugged into a regular radio, it works fine. I'd just now like to add the
ability to control the bass and treble (which the original configuration did not
have).

elfa

 

[John Woodgate]

I read in sci.electronics.design that elfa <[email protected]>

I literally cut the speaker (with amp inside) in half and substituted a
5 1/2 in speaker for the 2 1/2 (still keeping the 1 3/8 tweeter with cap
connection). When plugged into a regular radio, it works fine. I'd just
now like to add the ability to control the bass and treble (which the
original configuration did not have).

So you DO want a real tone-CONTROL circuit, NOT a crossover. Well, you
can't put any reasonable tone control circuit between an amplifier and a
loudspeaker.

 

[YD]

Thanks for your response. The amp is nothing more that a portable amplified
speaker system that you can buy for $20. They usually come with 2 1/2 inch
speakers and a battery compartment for 4 batteries. Some also have a provision
for plugging in an AC/DC adapter. The one I'm using has a 2 1/2 in speaker with
a 1 3/8 tweeter with a capacator connecting the two.

I literally cut the speaker (with amp inside) in half and substituted a 5 1/2 in
speaker for the 2 1/2 (still keeping the 1 3/8 tweeter with cap connection).
When plugged into a regular radio, it works fine. I'd just now like to add the
ability to control the bass and treble (which the original configuration did not
have).

elfa

Are you using the built-in amp or are you plugging the speaker
directly into the radio's speaker outlet?

- YD.

 

[elfa]

Are you using the built-in amp or are you plugging the speaker
directly into the radio's speaker outlet?

- YD.

I'm using the built in amp. The original amplified speaker is the kind designed
to plug into a portable radios earphone jack. So the input to the amplified
speaker will be directly from the an earphone jack.

This is basically what I doing. Taking a battery powered amplified speaker
designed to just plug into a portable radios earphone jack, replacing the 2 1/2
inch main speaker with one of 5 1/2 inches (keeping everything else intact).
It works fine....all I want to do is somehow add the ability to control the tone
with a passive circuit, either between amp and speaker (which I'm told is not
reasonable) or between earphone jack and the input jack of the amp.

elfa

 

[John Woodgate]

I read in sci.electronics.design that elfa <[email protected]>

between
earphone jack and the input jack of the amp.

That you can do, but it's a bit ambitious for a beginner.

 

[YD]

I'm using the built in amp. The original amplified speaker is the kind designed
to plug into a portable radios earphone jack. So the input to the amplified
speaker will be directly from the an earphone jack.

This is basically what I doing. Taking a battery powered amplified speaker
designed to just plug into a portable radios earphone jack, replacing the 2 1/2
inch main speaker with one of 5 1/2 inches (keeping everything else intact).
It works fine....all I want to do is somehow add the ability to control the tone
with a passive circuit, either between amp and speaker (which I'm told is not
reasonable) or between earphone jack and the input jack of the amp.

elfa

Ok, that's fine then. You can use a passive circuit at the amp input,
either in a separate box between the radio and amp or if space allows
inside the speaker box. Just cut the wire between the jack and amp and
put the control there. A passive Baxandall seems like just the ticket.
Be warned that there's quite a bit of attenuation so you may not get
all the volume this way.

- YD.

 

[elfa]

Ok, that's fine then. You can use a passive circuit at the amp input,
either in a separate box between the radio and amp or if space allows
inside the speaker box. Just cut the wire between the jack and amp and
put the control there. A passive Baxandall seems like just the ticket.
Be warned that there's quite a bit of attenuation so you may not get
all the volume this way.

- YD.

Thanks YD....now to just get the parts and try it.

elfa

 

[elfa]

Ok, that's fine then. You can use a passive circuit at the amp input,
either in a separate box between the radio and amp or if space allows
inside the speaker box. Just cut the wire between the jack and amp and
put the control there. A passive Baxandall seems like just the ticket.
Be warned that there's quite a bit of attenuation so you may not get
all the volume this way.

- YD.

Ooops....forgot another question. If I want to add a volume control between the
amp and speaker (the original speaker system didn't have volume control), what
value in ohms would you recommend in the way of a audio pot?

elfa

 

[John Woodgate]

(in <[email protected]>) about 'Newbie
here....treble and bass control for portable speakers', on Tue, 28 Oct
2003:

A passive Baxandall seems like just the ticket.
Be warned that there's quite a bit of attenuation so you may not get all
the volume this way.

There is no such thing as a 'passive Baxandall'; the circuit *depends*
on negative feedback.

 

[John Woodgate]

I read in sci.electronics.design that elfa <[email protected]>

Ooops....forgot another question. If I want to add a volume control
between the amp and speaker (the original speaker system didn't have
volume control), what value in ohms would you recommend in the way of a
audio pot?

Again, DON'T. Don't put ANYTHING between amp and loudspeaker. Put your
volume control with the tone control circuit.