dynaco a25xl crossover coil and resistors

[margus_]

Hi!

I need help. I want to upgrade my dynaco a25xl crossover parts, but I find difficult to choose right coil. As I have understand it must be 0.5 mH? Are there any other parameters that are also importand? https://www.hificollective.co.uk/catalog/-c-61_174.html there are so many variations.... maybe this one https://www.hificollective.co.uk/catalog/000-1034-05mh-jantzen-air-core-wire-coil.html ?
Same question with resistors, is there importand to use 5 w resistors or are 10 w also ok? And what type resistors are recommended? Can someone just suggest some certain products from that www.hificollective.co.uk site to make my life a bit easier?

Regards,
Margus

 

[R Swerdlow]

The first question you should ask is why do you want to replace an existing inductor coil. They do not age or wear. Unless the wire is broken there is no benefit from replacing it. Endless debates exist whether replacing capacitors can alter the sound of a speaker, but no such debates exist for inductor coils.

Since you asked… the most important feature of an inductor coil is it's rated inductance, such as 0.5 mH. That value comes from the number of wire windings. It's what makes an inductor coil work as a low-pass filter.

Other features that are important for inductors (but not quite as important) are:

• Air core (or wound on a plastic or wooden bobbin) vs. iron or steel core. Standard practice is to use air core for all audio crossovers, unless a large value inductor is required for a woofer circuit with a low crossover frequency. Iron core inductors use much less wire and as a result have lower DC resistance (DCR) and cost.
  
• Gauge of the copper wire. Thicker wire has less inherent DCR than thinner wire. Coils made with thicker wire are better in the sense that less DCR is better, but worse because they are larger in size and cost. If you must replace an existing coil, stay with the same thickness wire, as you may not have the space for a larger coil, and the crossover design may depend on the inherent DCR of the coil.

With resistors, it won't matter much whether you use 5 or 10 watt resistors. Resistors are inexpensive; in most cases, I'd use 10 watt resistors. These watt ratings refer to the power level a resistor can handle without failure. A higher watt rating will allow for greater power handling, but it will not alter the sound quality of a speaker.

 

[ictwoody]

If you want to replace your crossovers cmpleatky I have a pair of A25XL crossovers ready to go. They bipass the level switch and are built to hardware the "normal" position.

I know they are right through a lot of messages back and forth with WayneR here on AK. He's kinda an A25/XL expert. I'll post pictures shortly.

The only reason I didn't use them is I wount up building another set with higher end crossovers and resisters.... because, why not. This pair uses standard PE parts.

- Woody

 

[margus_]

Thanks for answers. Actually i have right now working crossover, that is rebuild to stay always on "normal" position. But it looks kind of ugly. I want to build just for fun a good looking crossover layout, thats why I need new parts. I dont want to destroy working solution before new crossover is ready

 

[ictwoody]

Here's a pic of my extra pair. Yours if you want them for the cost of a small flat rate mailer. Let me know.

- Woody

 

[captinzander]

Here's a pic of my extra pair. Yours if you want them for the cost of a small flat rate mailer. Let me know.

- Woody

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so i know this post if 3! years old. but if you still have your new crossover you built i would use it! i recently got a a25xl pair and the tweeter does not play in either speaker. so i figured i would start with the crossovers.

do you still have that crossover set you made?