Simple tone control?

Is *that* why many boomboxes and home stereos(cheap ones) have a tone
knob labeled "Bass< >Treble"?

All I notices with those is that turning it to the left made the sound
muffled and to the right made the sound more tinny/hissy. I didn't
notice that the bass was being boosted when the knob turned left or
that it was being reduced when turned right.

-CC
Click to expand...
These pots on the circuit references aren't on a common shaft.

In other words, you can have muffled *and* tinny/hissy! ;-)

Dave
 
On Nov 21, 7:03 am, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:

Unless you want a "tone control" that produces shrill treble and boomy bass,
you need to move the treble corner up, and the bass down.

_________________
Click to expand...
Is *that* why many boomboxes and home stereos(cheap ones) have a tone
knob labeled "Bass< >Treble"?

All I notices with those is that turning it to the left made the sound
muffled and to the right made the sound more tinny/hissy. I didn't
notice that the bass was being boosted when the knob turned left or
that it was being reduced when turned right.

-CC
 
On 21.11.11 5:53 , DaveC wrote:
I'd like to add a simple op amp-based tone control circuit to my preamp for
desktop speakers& sub that I'm modifying from stock.

This is the simplest I found:

http://www.simplecircuitdiagram.com/2010/02/03/single-op-amp-tone-control/

(I have +/- supplies so I will be eliminating all coupling caps and changing
Vcc/2 to ground.)

What are the positives and negatives to this design?

Better circuit (yet simple)?

Thanks.
Click to expand...

This is the classic Baxandall tone control.
There is plenty of material if Googling for
'baxandall'.

--

Tauno Voipio
 
This is the classic Baxandall tone control.
There is plenty of material if Googling for
'baxandall'.
Tauno Voipio
Click to expand...
Thanks! It really helps to know what it's called... ;-)

This page:

<http://sound.westhost.com/dwopa2.htm>

says:
"
This circuit must be driven from a low impedance, so connecting it after the
volume control (for example) is a no-no. Ideally, the output of an opamp will
be the source, thus ensuring the required low impedance.
"
The input to this circuit will be the output of a computer's sound card. I
don't know if it's an opamp driving the output or not.

What do you suggest to insure driving by low impedance? Add a buffer opamp
(gain of 1) at the input of this circuit?

Thanks.
 
On Thu, 24 Nov 2011 12:49:48 -0800, DaveC <invalid@invalid.net> wrote:

This is the classic Baxandall tone control.
There is plenty of material if Googling for
'baxandall'.
Tauno Voipio

Thanks! It really helps to know what it's called... ;-)

This page:

http://sound.westhost.com/dwopa2.htm

says:
"
This circuit must be driven from a low impedance, so connecting it after the
volume control (for example) is a no-no. Ideally, the output of an opamp will
be the source, thus ensuring the required low impedance.
"
The input to this circuit will be the output of a computer's sound card. I
don't know if it's an opamp driving the output or not.

What do you suggest to insure driving by low impedance? Add a buffer opamp
(gain of 1) at the input of this circuit?

Thanks.
Click to expand...
The sound card output will be fine for driving this.

d
 
"Tauno Voipio"
http://www.simplecircuitdiagram.com/2010/02/03/single-op-amp-tone-control/

This is the classic Baxandall tone control.
Click to expand...

** It's not actually.

Seems like a ballsed up version with missing resistors that will be become
unstable at full treble.


There is plenty of material if Googling for
'baxandall'.
Click to expand...

** And like most stuff on hobby web sites it is bunkum.

The "Baxandall" tone control design was published in Wireless World in
952 - it used valves. The network is different to the one in the link above
and produces variable turnover at both the high and low ends of the range.

http://www.novotone.be/_site/projets/Projet25/Baxandall%20WW.pdf



.... Phil
 
A general question:

Should pots used in the audio tone filter circuits be audio (log) taper? Or
does this apply only to volume pots?

Thanks.
 
On Fri, 25 Nov 2011 13:25:37 -0800, DaveC <invalid@invalid.net> wrote:

A general question:

Should pots used in the audio tone filter circuits be audio (log) taper? Or
does this apply only to volume pots?

Thanks.
Click to expand...
Linear

d
 
"DaveC" <invalid@invalid.net> wrote in message
news:0001HW.CAEF0B2B01AA85A4B04909DF@news.eternal-september.org...
I'd like to add a simple op amp-based tone control circuit to my preamp
for
desktop speakers & sub that I'm modifying from stock.

This is the simplest I found:

http://www.simplecircuitdiagram.com/2010/02/03/single-op-amp-tone-control/

(I have +/- supplies so I will be eliminating all coupling caps and
changing
Vcc/2 to ground.)

What are the positives and negatives to this design?

Better circuit (yet simple)?

Thanks.
Click to expand...
This circuit, "mechanically" lifted from the tube era into op-amp
implementation, has a flaw:
If the treble control is set to maximum, then its gain is not limited at
+20dB at 10...20kHz, but keeps rising as far as the gain-bandwidth product
of the op-amp allows. Input impedance goes down accordingly. It might result
in Hf oscillations in the whole audio chain, even to burning the speakers
out if say you leave input unconnected and close to the speaker cable.

To fix the (potential) problem:
- insert 470R in series with the input 4.7uF capacitor or insert 470R
between the wiper of the treble control and the inverting input of the
op-amp;
- throw a 47pF cap from the op-amp output to the op-amp inverting input.
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top