What are your favorite low volume (small) inductors and caps?

[JonW]

Hi Folks,

After a long time away from speaker building (I had a kid), I’m getting back into it. The current project is a quite small speaker, with an internal volume of only 5 liters. I’ll start another thread on the design and goals after things are farther along.

Due to the small cabinet size, I prefer not to rob the woofer of any more volume than needed by using huge caps and inductors in the crossover. I’ve noticed that, for example, on a prior project when I moved from Solen caps to Clarity Caps, the volume for a given uF cap value went up a lot. The Solens might be good to work with. For a given uF value are there other caps that are small and sound good to consider?

My last project also used 14 gauge air core inductors. Like the Clarity Caps, the big inductors are nice, but large. For a given mH value are iron core and/or higher gauged air core inductors smaller? Any compromise in sound quality (other than increased DCR)?

I’m using pricey, low distortion drivers so I want to use good quality crossover parts. Just wondering if there are any out there that you like that also happen to be small (of low volume) for a given uF or mH value. Thanks!

Here is a preview of the project. Note the CD case in there for scale.

[Face]

External crossover connected via 4 pole Speakon connectors.

[---k---]

He lives!

Good too see these little guys finally coming to life. I got no good answers to your question. I mean, if you're looking for small size, NPE caps are the way to go.

[BOBinGA]

Erse 250V poly caps are the smallest I've used. They are about 80% as large as PE or Solen and sound fine to me. But then again, I'm not a cap0file (yet?).

Its going to be hard to save space on air core coils. Everyone's 16ga wire is the same. But Jantsens from PE are very tall and narrow while Erse's are flat and wide, so that might be a factor. You can save a little space with 18ga and for values around 2 mH you only give up 0.2 ohms which I doubt would be audible. Also, air core and steel laminates are not much different in total volume. What you gain in less wire with a laminate you lose to the steel core. But laminates are much cheaper if that's a consideration.

-Bob

[JonMarsh]

Audyn metallized film for compactness; as Bob notes, you've just got to pay attention to the form factor and DCR.

[JonW]

External crossover connected via 4 pole Speakon connectors.

Hi Face,

I’ve got to keep the crossovers internal. Details to follow in the main project thread, when I get farther along with the project,

He lives!

Good too see these little guys finally coming to life. I got no good answers to your question. I mean, if you're looking for small size, NPE caps are the way to go.

Ryan!!

Nice to ‘see’ you again. Yes, I’m very happy to get at least a little time for speaker building. I don’t need to resort to microelectronics caps. The volume issue is not that pressing. Just looking for caps and inductors that might be smaller rather than larger for a given value.

[JonW]

Erse 250V poly caps are the smallest I've used. They are about 80% as large as PE or Solen and sound fine to me. But then again, I'm not a cap0file (yet?).

Its going to be hard to save space on air core coils. Everyone's 16ga wire is the same. But Jantsens from PE are very tall and narrow while Erse's are flat and wide, so that might be a factor. You can save a little space with 18ga and for values around 2 mH you only give up 0.2 ohms which I doubt would be audible. Also, air core and steel laminates are not much different in total volume. What you gain in less wire with a laminate you lose to the steel core. But laminates are much cheaper if that's a consideration.

-Bob

Audyn metallized film for compactness; as Bob notes, you've just got to pay attention to the form factor and DCR.

Hi Bob and Jon,

Thanks for the very helpful info! Form factor is good to know about. For this small project, the tall and narrow might be better, given that there is not a lot of cabinet side/bottom real estate onto which I will mount the crossovers. I do not yet have measurements or a preliminary crossover, so I do not know what values of caps and inductors I will be dealing with.

OK, no space savings with iron core inductors. Good to know. For air cores, looking at the extremes of 14 versus 18 gauge, I’m finding...

For 2.2 mH inductors:
18 gauge Jantzen is 1.93 x 1.18”, $13 (0.84 ohm DCR)
14 gauge Erse is 3 9/16” diameter, $37 (0.33 ohm DCR)

Hard to compare volumes directly due to the form factor difference you mentioned. But I’m guessing that the 18 gauges are smaller in total volume. True? If so, I have to decide if I’m willing to put up with the extra 0.5 ohm DCR versus the robbed volume. The DCR may not be an issue at all if I factor it into the crossover design. Not yet sure. For the volume impact on the woofer, I can run some WinISD calculations to get a rough idea if any difference will appear. Probably not at this level, but it will be easier to estimate when I have an idea of how the crossover is shaping up.


For 100 uF caps, diameter x length in mm’s:
Audyn is 61 x 62
ClarityCap SA is 120 x 84
ClarityCap PX is 71 x 71
ClarityCap ESA is 60 x 78
Dayton Audio 250 V is 51 x 77
Erse 400 V is 63 x 58
Erse 250V is 65 x 49
Solen is 56 x 72

The Audyn, Dayton, and Erse are around $26-28, the Solen is ~$36, the ClarityCap SA and PX are $52, and the ClarityCap ESA is $85.

It would be easier to have them in my hand and get a feel for the differences. But from the dimensions, I’m guessing that the Audyn, Dayton, Erse, and Solen are all roughly the same size. The ClarityCap SA is a big jump up. So avoid the ClarityCaps SA and maybe also the ClarityCap PX. Then all the rest are about equally good in terms of volume.

For some reason, I think of Solen as kind of a standard so maybe I’ll go with those or the ClarityCap ESA. Although I’m open to suggestions. I’m agnostic on the capophile front. I was happy with the ClarityCaps SA in my last project, but they do not look to be appropriate here.