Midrange tone control

sam14 · 8th August 2006, 11:41 AM

Hi, I would like to build a design based around the Pultec MEQ5 EQ but am not very electronically minded. I want to add some mid-cut at 1,2,3,4 Khz. Could someone tell me what the combo L & C values need to be at these freqs? Is it straightforward to calculate them? I have seen the MEQ5 schematic but couldn't figure it out! Doh! Thanks in advance

sreten · 8th August 2006, 12:19 PM

Hi,

you need to use or scale to the ~ 500R series resistor, the 270R
Q control and the inductor and capacitor values set by SW2.

This assumes your input can handle 600R loads.

/sreten.

sam14 · 8th August 2006, 10:44 PM

Thanks, Sreten. If I've worked it out correctly then, 1Khz is 108mH & 220nF; 2Khz is 34mH & 170nF; 3Khz is 34mH & 68nF and 4Khz is 34mH & 38nF? Also, is the transformer I/P essential or can I use 600R / 510R at the I/P of some unbalanced phono connectors? Thanks again.

sreten · 9th August 2006, 11:33 AM

Hi,

Download tina ti free circuit sim and check that it works.

(stick an op-amp in the corner unconnected to get it to work, then
use AC analysis to plot the frequency reponse, quick and easy)

600R is a fairly hefty load for an output - can the equipment
drive 600 ohm loads ?

/sreten.

sam14 · 9th August 2006, 01:42 PM

tina ti?

sreten · 11th August 2006, 03:44 PM

http://focus.ti.com/docs/toolsw/fold...t/tina-ti.html

sam14 · 11th August 2006, 08:42 PM

Thanks again, will give it a try

8th August 2006, 11:41 AM	#1
sam14 diyAudio Member Join Date: Jul 2004 Location: Leicester	Midrange tone control Hi, I would like to build a design based around the Pultec MEQ5 EQ but am not very electronically minded. I want to add some mid-cut at 1,2,3,4 Khz. Could someone tell me what the combo L & C values need to be at these freqs? Is it straightforward to calculate them? I have seen the MEQ5 schematic but couldn't figure it out! Doh! Thanks in advance

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8th August 2006, 12:19 PM	#2
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, you need to use or scale to the ~ 500R series resistor, the 270R Q control and the inductor and capacitor values set by SW2. This assumes your input can handle 600R loads. /sreten.

8th August 2006, 10:44 PM	#3
sam14 diyAudio Member Join Date: Jul 2004 Location: Leicester	Thanks, Sreten. If I've worked it out correctly then, 1Khz is 108mH & 220nF; 2Khz is 34mH & 170nF; 3Khz is 34mH & 68nF and 4Khz is 34mH & 38nF? Also, is the transformer I/P essential or can I use 600R / 510R at the I/P of some unbalanced phono connectors? Thanks again.

9th August 2006, 11:33 AM	#4
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, Download tina ti free circuit sim and check that it works. (stick an op-amp in the corner unconnected to get it to work, then use AC analysis to plot the frequency reponse, quick and easy) 600R is a fairly hefty load for an output - can the equipment drive 600 ohm loads ? /sreten.

9th August 2006, 01:42 PM	#5
sam14 diyAudio Member Join Date: Jul 2004 Location: Leicester	tina ti?

11th August 2006, 03:44 PM	#6
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	http://focus.ti.com/docs/toolsw/fold...t/tina-ti.html

11th August 2006, 08:42 PM	#7
sam14 diyAudio Member Join Date: Jul 2004 Location: Leicester	Thanks again, will give it a try

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