Question about inductors

[GeorgeO]

I'm planning a pair of two way for my son-stand mounted monitors using Scanspeak drivers. My question relates to inductors used in the crossovers. What role does the DCR values play in inductors and if I am getting them wound here in India Versus buying them from, say Solen or Madisound, what DCR should I specify.

TIA

George

 

[keith_correa]

Maybe this will help

 

[GeorgeO]

Yes but the quick and dirty is what a Guru friend of mine said-BTech IITK:

Hi George,

DCR is the DC resistance of the inductor. It's importance is based on the where it is used. The lower the DCR is better, but how much it effects the sound is what is important

A lower gauge wire has a lower DCR. But a lower DCR coil is more bulkier and much more expensive.

When I built your 1.5mH inductor, I used 18 gauge wire, the DCR was a little higher than the 14 gauge inductor, but the difference it made to the over all XO quality was minuscule and is inaudible.

The other errors in component tolerance and speaker deficiencies are more over bearing.

Basically don't worry too much about DCR.

 

[GeorgeO]

Yes, that is a detailed explanation. The quick and dirty, and what I was really looking for, is what I just received by email from a speaker building friend (BTech IITK):

Hi George,

DCR is the DC resistance of the inductor. It's importance is based on the where it is used. The lower the DCR is better, but how much it effects the sound is what is important

A lower gauge wire has a lower DCR. But a lower DCR coil is more bulkier and much more expensive.

When I built your 1.5mH inductor, I used 18 gauge wire, the DCR was a little higher than the 14 gauge inductor, but the difference it made to the over all XO quality was minuscule and is inaudible.

The other errors in component tolerance and speaker deficiencies are more over bearing.

Basically don't worry too much about DCR.

 

[anilva]

George,

Your friend is right as well as little compromising. DCR should be as less as possible. Using thicker gauges makes it possible. You want inductance and not it's associated big DC resistance. It will eat power obviously. Your friend is also right in saying low DCR coils are huge and bulky, because they are dependent on thicker the wire - better, higher the radius of the coil - better and lesser the number of turns - better.

If you can get coils wound locally using some of the above factors and still achieve the desired inductance, they will be in no way inferior to Solens etc. There is no big technology involved in this.

Cheers.

 

[viren bakhshi]

Hi George,

Get the inductors wound here, on a plastic bobbin, so that they have an air core. Even a rectangular bobbin is fine. For practical reasons, 18 gauge wire should be fine. Use the DC resistance of the inductor (say, 0.2 ohms) as part of the impedance seen by the driver, and adjust its Qts value. That way you will have compensated for the additional impedance in the design of the cabinet.

Regards,
Viren

 

[GeorgeO]

Thanks Anil and Viren for your inputs.

Unlike the past when I ddnt know about local options and bought my inductors from Madisound/Solen, this time I plan to get them wound locally, in a circular shape, using a plastic bobbin as the former. I had planned on 14 gauge AWG, since that is what the designer recommended, but will check on 18 gauge as well. Would the winder be able to predict dcr value before winding or is it possible only after it is wound? My values are 1, .50 and .25 mH, in pairs.

My son has the tweeters ordered, is on the lookout for mids-sometimes some amazing pre owned deals come up if you live in the US! Someone pointed to Usher drivers, saying that they are a good SS clone. Since the SS tweeters are already on the way, we decided to go for SS mids as well.

 

[borg]

try this calculator
Coil Physical Properties Calculator

 

[anilva]

Thanks Anil and Viren for your inputs.

Unlike the past when I ddnt know about local options and bought my inductors from Madisound/Solen, this time I plan to get them wound locally, in a circular shape, using a plastic bobbin as the former. I had planned on 14 gauge AWG, since that is what the designer recommended, but will check on 18 gauge as well. Would the winder be able to predict dcr value before winding or is it possible only after it is wound? My values are 1, .50 and .25 mH, in pairs.

My son has the tweeters ordered, is on the lookout for mids-sometimes some amazing pre owned deals come up if you live in the US! Someone pointed to Usher drivers, saying that they are a good SS clone. Since the SS tweeters are already on the way, we decided to go for SS mids as well.

The inductors design software (which many exist on the net, and some of them pointed here as well) will tell you number of turns required, what DCR etc, based on the input parameters. Quite simple. Of course one needs to wind the coil tight and layers close to each other, without lot of gaps.

Cheers.

 

[GeorgeO]

Thanks Anil

Points noted. I will see some inductors wound by the vendor(from Hyderabad) before I order. Much rather order from someone who can do it for me reasonably well than try to do it on my own!

 

[kanwar]

George,

Why not try Active X-overs instead of passives?

High DCR also reduces damping factor available at woofer end.

 

[GeorgeO]

Kanwar

I want to make one set which use passive crossovers, I prefer not to meddle with it, since it sounds so nice as it is. I may do an active a bit later-you do realise though that actives require additional amps, as well as either Behringer type unit both of which come at a cost? passive crossover doesnt need these and the components dont cost much.

George