Passive Mastering EQ

[5v333]

ok i got two sets of parts for thoose inductors and order is on the way.

 

[ruffrecords]

ok i got two sets of parts for thoose inductors and order is on the way.

Cool

Ian

 

[SIXTYNINER]

Hi,
possible a version with inductors as on Igs iQ ?

 

[ruffrecords]

Hi,
possible a version with inductors as on Igs iQ ?

The current design does use inductors.

Cheers

Ian

 

[5v333]

sorry for taking so long time with the inductors...

core parts are here. just ordered 240m of wire.

 

[ruffrecords]

sorry for taking so long time with the inductors...

core parts are here. just ordered 240m of wire.

No problem. Development is proceeding gently.

Cheers

Ian

 

[ruffrecords]

Last of the PCBs arrived the other day. I have ordered the Grayhill switches for frequency selection. When they arrive I will start building a complete channel.

Cheers

Ian

 

[ilfungo]

Great IAN!!!

 

[5v333]

Ian!

i rolled a bobbin today.
didnt turn out the way i was hoping for exactly, cause i used a 0.35mm wire instead of 28awg  (0.32mm) so each layer containd less turns.

i rolled it the way i had planned anyway to see how it would turn out.

with the 630AL cores and the turn counts i got for each winding i got:

31mH
68mH
181mH
252mH
490mH
750mH

the 31mH winding could be done closer to 50mH instead
and the 252mH winding could be done something about 297mH with an extra layer of turns.

but i need to rip it apart and remake it. or if you like theese numbers better, ill do another one with same recepie.

i need to order more copper wire cause the first attempt was for warming up.

what do you think?

 

[ruffrecords]

Those values will be OK. After I designed that inductor, the customer came back with a list of frequencies for each band and the highest was a bit too low for the 50mH winding so 31mH is no problem.

Cheers

Ian

 

[5v333]

Ok.

total DCR is about 19.1R

 

[ruffrecords]

Ok.

total DCR is about 19.1R

Perfect.

Cheers

Ian

 

[steves.mastering]

Just showing my interest,

Keep up the good work, looks like a great project

 

[r2d2]

Just showing my interest,

Keep up the good work, looks like a great project

+1 here  : )+

some news about ?
cheers

 

[ruffrecords]

I just finished testing a shelving version of the lowest EQ band, because the first customer wants the bottom most and top most bands to be shelving rather than peaking. I used the same inductor as used in the peaking version but the inductor values may need altering.

There seems to be no accepted definition of the frequency of a shelving EQ so the following plots are listed by inductor value. Draw you own conclusions about how you would define them:

750mH boost and cut:

500mH boost and cut:

300mH boost and cut:

200mH boost/cut:

100mH boost/cut:

55mH boost/cut:

Unlike the peaking version, the turnover frequency is different for cut then for boost. This is because the basic attenuator is 10dB so the resistance of the lower arm is less than that of the upper one.

Cheers

Ian

 

[skal1]

Just showing my interest, are all the band switchable from peak to  shelf

regards

slkal

 

[ruffrecords]

Just showing my interest, are all the band switchable from peak to  shelf

regards

slkal

No. You can build them as peaking or shelving but they are not switchable. They are really all intended to be peaking - the Q required for mastering is quite low - around 0.6 - so the peaks are quite broad. There is not a huge difference in shape between a bass shelving curve and a bass peaking curve (you can see the peaking ones in an earlier post). Also there is not much point having a mid band shelving so if you did do it you would only do it the the highest and lowest bands.

Cheers

Ian

 

[5v333]

Ian
When doing the shelfs instead of peak, do you get the same amount of gains?

 

[ruffrecords]

Ian
When doing the shelfs instead of peak, do you get the same amount of gains?

The maximum boost and cut should be the same as for the peaking EQ.

Cheers

Ian

 

[skal1]

Hi Ian,

i was just wondering  , are the inductors  you are going to choose, custom or off the shelf , and will the peaking / shelf  eq  circuit use the same inductor.
cheers

skal1