EMI TG12414 Inductor

I am looking for info concerning the inductor. The value are on the schematic but I have no idea how to find the esr value.
Cheers

Does not compute. ESR is for capacitors...?

Do you want the resistance of each tap?

gyraf said:

Does not compute. ESR is for capacitors...?

Click to expand...

But also for inductor. The wire lenght introduce losses and if the inductor has a core it also introduces losses
Those losses are what limits the Q factor in a passive eq.

drask said:

Do you want the resistance of each tap?

Click to expand...

With pleasure sir, that's exactly what I need. Do you have original units ?

drask said:

Do you want the resistance of each tap?

Click to expand...

With pleasure sir, that's exactly what I need. Do you have original units ?
[/quote]
No I haven't it. But I built a prototype of this EQ.
I can check what I use for the inductors and the ESR.
Do you have the schematics?

yes I have the schematics.
How did you choose the esr ? Did you recalculate the value according to the Q factor ?

Niketouille said:

gyraf said:

Does not compute. ESR is for capacitors...?

Click to expand...

But also for inductor. The wire lenght introduce losses

Click to expand...

This loss's full descriptor is the series resistance.

and if the inductor has a core it also introduces losses

Click to expand...

these appear as a parallels resistor. I'm fully aware that some textbooks use the delta-y transformation to lump the series resistance and the equivalent loss resistance into one single element, but this just doesn't give a proper description over the whole operating range.

Those losses are what limits the Q factor in a passive eq.

Click to expand...

Yes and no. In a proper design, the losses influence the overall BW (I deliberately don't use the term "Q" because it is improper in a biquadratic equation) at the second-order. The series resistance is the main factor there. Again, in a properly designed product, the final BW would be governed by an external resistor, i.e. the inductor's intrinsic Q would be larger than what's needed for the intended performance. That's the case with the TG12412, where each inductor has a separate series resistor (R10, R17 & R19), which could be adjusted in case of manufacturing changes; in addition some of the taps (most of them in fact) have additional resistors (R1-9 & R11-16).
These series resistor govern mainly the max amplitude of EQ, the BW being governed by the relation between the inductance and the total series resistance. The loss resistance skews the shape of the bell.

Thank you very much for those precises explanations.
It seems that in the case of the tg12414 the serie resistor of each taps are so low they have only use one resistor to adjust the BW/Q.
That leads me to another question, how do I choose my inductor characteristic in such a design ? The wire lengh seems not to be a factor anymore as long as the serie resistor is low compare to 200ohms.
Actually the real question is, what do I tell Sir Chrion so he can make me some inductor for this project ?

Also in the manual I am reading "the frequency of half lift or cut is 500Hz". Does someone know what "half lift/cut" mean ?

Niketouille said:

Thank you very much for those precises explanations.
It seems that in the case of the tg12414 the serie resistor of each taps are so low they have only use one resistor to adjust the BW/Q.
That leads me to another question, how do I choose my inductor characteristic in such a design ? The wire lengh seems not to be a factor anymore as long as the serie resistor is low compare to 200ohms.
Actually the real question is, what do I tell Sir Chrion so he can make me some inductor for this project ?

Click to expand...

You just tell him to make the DCR lower than 200r. [/quote] then you will adjust the value of the series resistance for expected performance.

Also in the manual I am reading "the frequency of half lift or cut is 500Hz". Does someone know what "half lift/cut" mean ?

Click to expand...

I suspect it is in respect to a shelving EQ...can you put more context? La phrase complète, si possible...

3.5.5 Bass Control

This provides a flat position and five 2dB steps of lift or cut.  Although it is called a bass control, the frequency of half lift or cut is actually 500Hz.  The frequency response obtained at the various settings is shown in Drawing No. 375.  The circuit is described in 12.2.  Since the circuit has no output capacitor, a 6.8μF capacitor is provided externally with 150kΩ to the 0 V line to prevent a large plop when the fader is inserted.

the Brits use "lift" instead of "boost"

and they put clothing around their tea pots,

I forgot to say that it is not a shelving eq.

Niketouille said:

3.5.5 Bass Control

This provides a flat position and five 2dB steps of lift or cut.  Although it is called a bass control, the frequency of half lift or cut is actually 500Hz.  The frequency response obtained at the various settings is shown in Drawing No. 375.  The circuit is described in 12.2.  Since the circuit has no output capacitor, a 6.8μF capacitor is provided externally with 150kΩ to the 0 V line to prevent a large plop when the fader is inserted.

Click to expand...

With a shelving EQ you normally specifiy it by the frequency at which the shelf occurs. To reach the shelf you obviously have to start boosting or cutting at a higher frequency. To obtain a 10dB shelf boost at 100Hz means that in practice you need to begin boosting around 500Hz. This probably what EMI calls the frequency of half lift or cut.

Cheers

Ian

Niketouille said:

3.5.5 Bass Control

This provides a flat position and five 2dB steps of lift or cut.  Although it is called a bass control, the frequency of half lift or cut is actually 500Hz.  The frequency response obtained at the various settings is shown in Drawing No. 375.  The circuit is described in 12.2.  Since the circuit has no output capacitor, a 6.8μF capacitor is provided externally with 150kΩ to the 0 V line to prevent a large plop when the fader is inserted.

Click to expand...

A shelving EQ doesn't have a definite "center frequency", like a bell EQ has, so very often the boost/cut is defined with a frequency, close to where the response goes asymptotic. You will see LF EQ +18dB at 100Hz, and the actual graph will do that but it will be about +3dB at 1kHz, +10 at 250Hz and +20 at 30Hz. Defining half lift makes this frequency independant of the amount of boost/cut. E.g. for 6dB boost, the half lift will be the +3dB point, for 12dB, it will be the +6dB point. Very British.

So what does it could means as it is not a shelving eq ?

Niketouille said:

So what does it could means as it is not a shelving eq ?

Click to expand...

Can you post a graph?

I don't have them but schematic is exactly the same as the tg12414...

My bad, there is a resistor in serie with the inductor and no capacitor... so it is shelving I guess. It all makes sense now.

Niketouille said:

My bad, there is a resistor in serie with the inductor and no capacitor... so it is shelving I guess. It all makes sense now.

Click to expand...

On the LF control, the BL, MED and SH positions are bells and the LOW position has only LR in circuit, which makes it a shelf; the HIGH position has an RC circuit, making ita shelf, but with a very low turnover frequency, meaning that everything is boost or cut, except LF.
It's kinda hard to figure what it's good for. I guess EMI designers did that because they could, probably not because anybody asked for it..

Hey guys,

On the TG 12414, the schematics i have give a Q factor resistor 1Mohm value, it's a huge BW Q factor? no?