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Reno1 7th August 2012 11:57 AM

Tone Control Filter
 
1 Attachment(s)
Hi I have been playing with this tone control circuit to replace my baxandall tone control. This circuit is designed to cut the bass, mid and treble -26db and to boost them 6db. It works fine however, I want to raise the boost a bit higher than 6db (maybe 12db) so would like to know which resistors I would have to replace. Thanks for you time, any help is much appreciated

Osvaldo de Banfield 7th August 2012 12:15 PM

The circuit is strange, I never saw none similar to this, but appears to me that increasing R19 and R35 would be a starting point.

Jay 7th August 2012 01:58 PM

Quote:

Originally Posted by Reno1 (Post 3117652)
This circuit is designed to cut the bass, mid and treble -26db and to boost them 6db.

Do you mean AFTER the level is elevated by the first opamp?

The first opamp already has around 47k/8k2=5.7=15.1dB of gain. The second opamp more or less cut both frequency ends and the third opamp notch the midrange.

So if you want more gain, instead of altering the gain of the second and third opamps you can also increase the gain of the first opamp, which is already high.

Strange, if not bad tone control design imo.

Reno1 7th August 2012 02:43 PM

Hi thanks for your response, I am happy with the 15db gain on the volume pot, but I just want to be able to boost the actual tone frequencies more than 6db thanks

Reno1 7th August 2012 06:24 PM

Anyone?

Jay 7th August 2012 08:14 PM

Quote:

Originally Posted by Reno1 (Post 3117820)
I am happy with the 15db gain on the volume pot, but I just want to be able to boost the actual tone frequencies more than 6db thanks

Oh so you want to boost above volume level...

This depends on the value of your pots. If the resistance on the left of the wiper equal to the resistance on the right, you get 0dB. So to increase gain what you want is to increase the pot (e.g. to 100K) or to lower R22, R17 and R25 to half of it (6k8-->3k3, 5k6-->2k7)

Reno1 7th August 2012 09:50 PM

Sorry I dont quit understand what you are saying, all I am trying to do is boost the individual frequencies above 6db, so I want to know which resistors to change without affecting the turnover frequency thanks

Jay 7th August 2012 11:04 PM

1 Attachment(s)
Turnover frequency is determined by the RC networks, you don't want to change that. 330n (C10) determines the low frequency, 1n (C13) determines the high frequency and 47n (C14) determines the midrange frequency. See pic

Jay 7th August 2012 11:16 PM

1 Attachment(s)
I think it is better to design the TC where you can control the pole frequencies ala parametric EQ. Here is a good one from www.sevenwoodsaudio.com

Reno1 7th August 2012 11:25 PM

Thanks for your time it is very much appreciated, I will make the following changes tomorrow and let you know how it turns out, thanks again


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