Best sounding inductors on sale now

Not all inductors are created equal,

I'd like to build a passive EQ using LC networks, for line level sources

Has anyone here experimented with different manufacturers?

Please supply an objective definition of 'best'  ;D

Cheers

Ian

The main challenge with inductors is making them as much as possible impervious to the effects of saturation.
The common approach is to largely overdesign.
Favour gapped cores, that are much more linear AND accurate than non-gapped ones. E.g. non-gapped cores tolerance is typically about +30/-20%, when gapped ones is +/-3%.
It is possible to calculate the induction resulting from the circuit operation, and use it to stay well behind saturation, but these calculations are very fastidious and generally end up giving results that are -50/+100% off.
Best practice is to evaluate in circuit.
Actually, it seems some prefer EQ's where inductors create some distortion. they call it mojo...
Stay away from iron cores, unless you like distortion.

I suppose that best would, in my case, the ones that have the deepest, most solid-sounding effect on the signal.

Which ones have the largest core, on the market now?

I looked at Carnhill's site and they have a bunch of inductors which might work for me.  Are there any that have larger cores, perhaps?

MaxDM said:

I suppose that best would, in my case, the ones that have the deepest, most solid-sounding effect on the signal.

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But that is subjective so different people will have different opinions on that, which I why I asked for an objective definition. Not to worry, what matters is what you prefer. You will just have to listen and make your own mind up

Which ones have the largest core, on the market now?

I looked at Carnhill's site and they have a bunch of inductors which might work for me.  Are there any that have larger cores, perhaps?

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You also need to consider the signal level passing through the EQ. Many of the Carnhill cores are derived from Neve designs which were operated typically at about -10dBu or less. More modern IC based designs tend to operate about 10dB higher so the danger of hitting saturation would be much greater.

Cheers

Ian

ruffrecords said:

But that is subjective so different people will have different opinions on that, which I why I asked for an objective definition. Not to worry, what matters is what you prefer. You will just have to listen and make your own mind upYou also need to consider the signal level passing through the EQ. Many of the Carnhill cores are derived from Neve designs which were operated typically at about -10dBu or less. More modern IC based designs tend to operate about 10dB higher so the danger of hitting saturation would be much greater.

Cheers

Ian

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Hmm..  ok.

How about inductors that are in the same category as 1950's passive, line level, EQ's?

MaxDM said:

Hmm..  ok.

How about inductors that are in the same category as 1950's passive, line level, EQ's?

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I do not know of any. Do you?

Cheers

IAn

This is an area where you will need to experiment and decide for yourself.  Carnhill,  Cinemag,  Sowter,  are some one's to check out.

You can’t pluck a component out of context in a design and say good or bad. If you have an EQ you like then post the schematic and the brain trust will have something to go on.

Gold said:

You can’t pluck a component out of context in a design and say good or bad. If you have an EQ you like then post the schematic and the brain trust will have something to go on.

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I would be using standard LCR formulas to make a line level, 600 ohm source boosting EQ, in the style of the Pultec EQ's, but also in the style of fully passive Eq's

You could isolate the midrange Boost in a Pultec out of the schematic, and that would be an example, except that I intend on also making some low-frequency LCR bandpass filters as well, instead of the RC bass filters on the Pultec, which are obviously shelving.

But, as I take it, the main options available are Sowter and Carnhill?

MaxDM said:

I would be using standard LCR formulas to make a line level, 600 ohm source boosting EQ, in the style of the Pultec EQ's, but also in the style of fully passive Eq's

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What's the difference? A Pultec is a " fully passive EQ" with a gain make-up amp.

But, as I take it, the main options available are Sowter and Carnhill?

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The main option is winding your own. Try it, you'll see it's not difficult at all, just a tad tedious.
Calculations arequite simmple; when you know the desired inductance L and the specific inductance Al of teh chosen core, the number of turns N is given by
N=sqrt(L/Al)
You need to wind a little more than the calculated value, so you can adjust the inductance by unwinding some turns. The inductance should be measured in circuit, with the core fully assembled and pressed.

MaxDM said:

But, as I take it, the main options available are Sowter and Carnhill?

Click to expand...

Cinemag also do a range of inductors. They are making me a custom pair for a 600 ohm EQ right now.

Cheers

Ian

Pultec inductor is a toroid powdered permalloy core (MP type), as were pretty much all “1950s types” The rest mentioned here are ferrites of various formulations. If you’re thinking of winding your own as suggested, winding toroids is a bit trickier (or more tedious, depending on how you do it). But whether you wind your own or buy off the shelf, I doubt you’ll hear any difference between suitable ferrites assuming that you use gapped types with lower AL values (often sold as “power ferrites”) that are appropriately sized for the frequencies of interest (this is taken care of for you with off-the-shelf inductors). So hunting around for some magical ferrite core is not going to be very fruitful IMO. It’s may be worth comparing MP toroids with equivalent ferrite types though. Carnhill is the only vendor i’m aware of that sells MP toroid inductors (or at least they were in the design guide last i checked). Of course, they sell ferrite types as well. I don’t recall seeing any toroids from Cinemag (but they may sell some i don’t know about).

Vintage Windings makes some toroid MP.

http://www.vintagewindings.com/products/products.html