A Audio and hi-fi forum. AudioBanter

Go Back   Home » AudioBanter forum » rec.audio » Tech
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Simple tone control?



 
 
Thread Tools Display Modes
  #21  
Old November 25th 11, 09:25 PM posted to alt.engineering.electrical,sci.electronics.design,sci.electronics.repair,rec.audio.tech
DaveC[_2_]
external usenet poster
 
Posts: 43
Default Simple tone control?

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.

Ads
  #22  
Old November 25th 11, 09:30 PM posted to alt.engineering.electrical,sci.electronics.design,sci.electronics.repair,rec.audio.tech
Don Pearce[_3_]
external usenet poster
 
Posts: 2,268
Default Simple tone control?

On Fri, 25 Nov 2011 13:25:37 -0800, DaveC > 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.


Linear

d
  #23  
Old December 30th 11, 10:57 AM posted to alt.engineering.electrical,sci.electronics.design,sci.electronics.repair,rec.audio.tech
Alex Pogossov
external usenet poster
 
Posts: 95
Default Simple tone control?


"DaveC" > wrote in message
...
> 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.


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.


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Baxandall (of tone control fame) Engineer[_2_] Vacuum Tubes 3 April 7th 09 10:11 AM
Eico Tone Control Mod Jon Yaeger Vacuum Tubes 25 December 8th 07 01:25 PM
Tube Equaliser/Tone Control Iain Churches Vacuum Tubes 23 April 29th 07 03:11 AM
Proposed Eico Tone Control Mod Jon Yaeger Vacuum Tubes 14 December 28th 05 09:09 PM
Line stage/tone control Adam Stouffer Vacuum Tubes 1 June 20th 04 09:35 PM


All times are GMT +1. The time now is 01:08 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Copyright 2004-2019 AudioBanter.
The comments are property of their posters.