Simple tone control?

Tue Nov 22, 2011 7:02 am   

On 11/21/2011 11:47 PM, UnsteadyKen wrote:


You're links are broken/segmented.
<http://www.harmankardon.com/EN-US/Products/Pages/ProductDetails.aspx?PID=SOUNDSTICKS3AM>
Does work...

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Only $169

Jeff-1.0

--
"Everything from Crackers to Coffins"

Tue Nov 22, 2011 7:07 am   

"Jeffrey Angus"



** Not from outside the USA it don't.

And the UK one is the same.

How boring of them.


.... Phil

Tue Nov 22, 2011 7:22 am   

On 11/22/2011 12:07 AM, Phil Allison wrote:

Well that sucks, what's the point of that?

Jeff-1.0

--
"Everything from Crackers to Coffins"

Tue Nov 22, 2011 7:31 am   

On Tue, 22 Nov 2011 00:22:29 -0600, Jeffrey Angus <grendelair_at_aim.com>
wrote:


Just need a proxy within the USA - always useful to have one available
for every major country.

d

Tue Nov 22, 2011 9:25 pm   

DaveC wrote:


It looks bog-standard to me. Go ahead and use it and use your mind to go
on to greater things! :-)

Cheers!
Rich

Thu Nov 24, 2011 1:05 am   

These pots on the circuit references aren't on a common shaft.

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

Dave

Thu Nov 24, 2011 1:48 am   

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


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

Thu Nov 24, 2011 7:48 am   

On 21.11.11 5:53 , DaveC wrote:


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

--

Tauno Voipio

Thu Nov 24, 2011 9:49 pm   

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.

Thu Nov 24, 2011 10:19 pm   

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


The sound card output will be fine for driving this.

d

Fri Nov 25, 2011 12:07 am   

"Tauno Voipio"


** It's not actually.

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




** 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

Fri Nov 25, 2011 10:25 pm   

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.

Fri Nov 25, 2011 10:30 pm   

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


Linear

d

Fri Dec 30, 2011 11:57 am   

"DaveC" <invalid_at_invalid.net> wrote in message
news:0001HW.CAEF0B2B01AA85A4B04909DF_at_news.eternal-september.org...

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.