Coil Pile

[sendler]

For those of you that got tired of following the Sure 2X100 thread, here is a photo that I posted over there of all of the coils that I have listened to.
I've listened to quite a few different coils including the ever popular T106 type 2 toroids from 41Hz and the Ferroxcube toroids as found in the ClassD Audio amps (much better sounding but leak like an air core) with three different types of wire. 14ga Litz wrapped and unwrapped, 18ga solid, and Belden 14 guage solid. And other recommended favorites from Toko, Sagami, CoilCraft, ect. The Wurth XXL were tried on a tip from another member or I wouldn't even have glanced at them. They look just like what you are taking out. Luckily I am open minded. I like them by far the best. They even sound better than my Belden air toroids in many ways, have a 13 amp saturation rating and they fit right in the stock location. I will use them exclusively. There are tens of very similar looking coils and tens more of larger types but the Wurth XXL have the best sonics of the ones I have tried.
http://katalog.we-online.de/kataloge...7447709004.pdf

[audi0]

nice collection! you have been busy

[wwenze]

That is a whole lot of work!

What is the value of the Wurth used?

[sendler]

Originally Posted by wwenze

That is a whole lot of work!

What is the value of the Wurth used?

The Wurth is available in smaller values that none of the other manufacturer's 10 amp coils are. I have tried them in 6.8, 4.7, and 3.5uH. I like 4.7 and 3.5 with .47uf caps for each position including the zobel with 15 ohms. They are very transparent at these low values but still provide excellent suppression of the 650KHz switching wave as evaluated with an AM radio sniffing for noise. With the 3.5, careful optimization of the zobel is required to keep the peaking from coming to far down into the audio band and brightening the sound. The Sagami sounded nice too but don't offer the 10 amp coil any smaller than 10uH, and are larger than the board space.

[kristleifur]

[This picture is suitable for framing]

Thanks for all the good info!

[boudy]

Where did you buy the XXL? I can't find them anywhere.

[sendler]

Originally Posted by boudy

Where did you buy the XXL? I can't find them anywhere.

Digikey is sold out. Maybe they will get more. They had a few hundred but since I made my post, some one must have bought them all.
Digi-Key - 732-1239-1-ND (Manufacturer - 7447709004)

[teamacc]

farnell still has some 10uh in stock, just google wurth xxl XXuH
replace the XX with the value you want

[wwenze]

How important is tolerance? The Wurths are rated 20%.

[sendler]

Originally Posted by wwenze

How important is tolerance? The Wurths are rated 20%.

Due to the ultra low values we are dealing with, all of the coils in this range are rated at 20%. It's very difficult to even measure down to an accuracy better than that at home with values below 10uH. The Wurth XXL coils sound the best though, regardless of whatever tolerance they are rated for. I have two amps with identical mods using them and the comparison between them is very close to the same. Too bad it seems that they may be obsolete or something as they are not in stock any more at places that used to stock them. Wurth has two newer model numbers that are similar but don't sound as good. I hope after finally finding a small format, shielded coil that I like that they aren't out of production.