Where can I buy Inductors & Capacitors?

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I hope you are enjoying your new hobby! There is alot of information (and disinformation) out there, and it can be daunting.

I highly recommend reading any of Rod Elliott's articles here:

Particularly, read the articles on passive crossover design, and the articles dealing with capacitors and inductors individually.

A summary of the types of components and their characteristics follows:


For crossovers you will need bipolar (or non-polar) capacitors. Most aluminum electrolytic capacitors are polarized and therefore unsuitable. Non-polar aluminum electrolytics are available, and are usually the least expensive capacitor suitable for use in crossovers. Compared to film type capacitors, aluminum electrolytics have higher series resistance, worse tolerance, non-linear capacitance with frequency, and degrading capacitance with age. For these and other less objective reasons they are considered by most to be considerably inferior to film types. The only application where electrolytics are conditionally recommended is where very large values of capacitance are needed (say, for example greater than 20uF of capacitance).

There are many different types of film capacitors, and there is much controversy surrounding the benefits of different types. My recommendation is to stick with the components that provide the best personal value for your money (letting you decide what you value and how much money that is worth).


Available in two basic types, air cored or ferromagnetic cored. The first having no ferromagnetic former on which the inductor is wound, the second having such a former. The reason for having a former is to increase the inductance for a given size (and usually cost) inductor. The disadvantage of ferromagnetic cores is increased distortion due to hysteresis of the core. This is more pronounced with higher frequencies than with low ones and with higher current than with low current. The usable frequency of a ferromagnetic cored inductor depends on the core type, but generally is fairly low, in the high hundreds to low thousands of Hertz. This makes air core inductors more suitable for high frequency crossovers such as midrange and tweeter crossovers.


Available in wire-wound or metal oxide for passive crossover level power ratings. Wire-wound inductors are further separated into inductive vs. non-inductive types. A recent thread shows some measurements of resistance and inductance for some commonly available wire-wounds. The inductance of standard wire-wound resistors is not appreciably significant compared to the inductance of speaker voice coils, particularly in the woofer and midrange circuits but extensible to tweeter circuits. Non-inductive resistors may have their place in tweeter circuits where tweeters with very low inductance are used and high resistance values are needed, but this would be the exception rather than the rule.

I will now deviate from what could be considered (or construed as) general consensus and offer my personal list of suppliers:

Bennic brand of non-polar electrolytics and film capacitors. Good quality, good value for me. If MCM does not have them on sale, I buy them here.
Madisound brand of 15W and 25W resistors.
Madisound brand of inductors; well made but a little expensive.

Bennic brand of film capacitors. They have a sale on these this month (February 2008) but are normally more expensive than madisound. They do not have good prices on non-polar electrolytic capacitors. If you have a lot of Bennic capacitors to order when they are on sale, it can be worth it to pay the reasonable shipping.
AMS inductors are fairly priced, sometimes on sale or clearance.

Dayton brand of capacitors. These look identical to Bennic and are claimed by most to be made by Bennic for Dayton.
Non-branded non-polar electrolytics are much physically smaller than Bennic non-polars for the same value, but don't measure appreciably worse. Inductors are over-priced IMO. (Compare their Erse prices to Zalytron and you will see what I mean). They have a good selection of inexpensive 5W, 10W, and 20W wire-wound resistors.

Not the easiest to order from (have to phone in orders), but have excellent prices on Erse inductors. I consider Erse inductors to be of excellent quality. I personally shop here first for inductors, you can save a lot of money doing so.

I hope that this helps.

for crossover inductors and capacitors I use Madisound and PartsExpress.

I will echo the comments with respect to Mouser, Digikey, Allied, Avnet, Future for other stuff. Mouser and Future carry WIMA polypropylene caps which are great for audio. I order from Madisound and Digikey probably once a week.
THANKS A LOT GT! That will save me a few headaches in the future. I knew to get nonpolar, but very glad you mentioned it due to I may not have remembered when ordering. I will save this thread for future reference.

Digikey was the only place I knew of to get the components. But when I went searching I realized quickly that I didnt know enough to start buying stuff.

(PS: It is more of a new department of an old hobby. I am just slowly needing to dig deeper to get what I want. :) )
You are welcome! I just ordered a few hundred dollars worth of crossover parts, so this information was fresh on my mind and wallet! I really can't believe the price of inductors these days. I have an old 10lb spool of 16AWG wire, but haven't been tempted to wind my own until now!

I noticed in your other post that you are going to be basing the crossovers off of the rated impedance of the drivers. I started out this way myself, and it really is the luck of the draw whether or not it works out or not. The impedance of a driver is constantly changing over the frequency range and it may or may not be close to the rated impedance at the crossover frequency. I will post a reply in that thread so that this one stays on topic.

On another note, I just tested a bunch of entry level capacitors, watch for my post on how they measure up.

Best regards everyone,
And you can probably save yourself a LOT of time (and also learn a lot) if you order the (free) paper versions of some of the catalogs. Mouser.com and alliedelec.com, for example, have excellent catalogs, with thousands of pages, and pictures of almost every product (Allied's are now even mostly in color.). They are great references to have on hand, as well as great learning tools, and also often make finding parts much easier and faster than searching on their websites, especially when you don't quite know exactly what you're looking for, or don't know what all might be available.

P.S. While not as good or as large, generally, as the others, Jameco.com does have certain things that the others don't have, and some things that are worth buying there instead of somewhere else. Also, for 'surplus' components, bgmicro.com sometimes has great deals. While I'm at it: I used to occasionally also find good stuff at a place called "Surplus Sales of Nebraska". I don't have their URL. Sorry.
gootee said:
And you can probably save yourself a LOT of time (and also learn a lot) if you order the (free) paper versions of some of the catalogs.

"Surplus Sales of Nebraska". I don't have their URL. Sorry.

The paper versions are invaluable.

Surplus of Nebraska has micas, polystyrenes, relays, rheostats etc.

As far as I am concerned, the best online catalog is McMaster-Carr -- it is extremely quick and very well organized.
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