[HAM] leslie crossover

[David Anderson]

Colin,

This is a more complicated question than you might think.

Earlier Leslie crossovers in square wooden boxes were wound on  
laminated iron cores (like a transformer), and not always the same.  
I've seen some wound on straight laminations and some wound on C- 
shaped laminations.

The later crossovers used a round ferrite core, a cheaper, but  
inferior way of making an inductor. Leslie probably switched to  
ferrite cores because they became available and represented a cost  
savings.

The ferrite core inductors have ~twice the DC resistance of the  
earlier laminated core inductors. That means more power lost in the  
crossover.

It's hard to say exactly what length of wire is required to produce a  
specific inductance. It would be a job to unwind one to find out, and  
it depends on the core.

If you need one, I'd buy a modern laminated iron core inductor.

Try some of these:

http://www.partsexpress.com/erse-16-gauge-inductors.cfm

or these:

http://www.partsexpress.com/18-gauge-laminated-core-inductors.cfm

With inductors, if you want an exact value not provided, you can  
often buy a higher value and unwind it until you get the value you  
want. You have to have an inductance meter or an impedance bridge.

If you're rebuilding or repairing a crossover, definitely replace the  
capacitors using some kind of metallized polypropylene like Solen,  
Dayton, or GE Motor Run caps.

David Anderson

On Jun 22, 2008, at 8:21 AM, colin43 at blueyonder.co.uk wrote:

> Does anyone know the gauge of enamelled wire and what length is  
> used to
> get 5.2mH and 3.2mH in a stock leslie crossover,also what is the  
> diameter
> of the inductor core and is it iron or ferrite.
> Thanks Colin Brown.