Building a pedal (Leslie 16/Vibratone)

[jeff]

I've been searching and searching but can't find an answer. Please help

What should the inductor rating be for a crossover? I know the value is 1.2mH but what mA?

100W amp=?mA
50W amp =?mA

Knowing the wattage of an amp tells you what the voltage/current is but how do you figure the current for a X watt amp with a Y ohm speaker. If you know the value of the speaker is 4 ohm then V/I=R but how can you solve for I if you don't know V?

Thank You
  Jeff

[sluckey]

how do you figure the current for a X watt amp with a Y ohm speaker

P = I²R, so I² = P/R, and I = √P/R.

[jeff]

There's air core, iron core, ferrite core, apple core, hardcore, marine core, peace core, core gumbo.... I don't know what to use, will this work?

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=255-050

[sluckey]

What should the inductor rating be for a crossover? I know the value is 1.2mH but what mA?

We need more info. What kind of crossover? Speaker? Low level tone circuit? Show us a schematic.

The one you linked to is made for a speaker crossover network, but will certainly work in a low level tone network also (Might be kinda big though). When you say building a pedal I think of small signal stuff. The inductor would be physically small like that in a Cry Baby.

[jeff]

Sorry,

 This is for a Leslie 16/Fender Vibratone. http://www.nmia.com/~vrbass/vibratone/Vibratone.pdf Basically a passive "add on" in line from the amps output jack. The pedal bypasses the crossover filter to the main speaker and disconnects the Leslie speaker or connects the main speaker with filtered mids plus the Leslie with filtered out lows.
 
I just found this on line but I don't know if it's what I need http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=255-050&scqty=1 Not sure what type of core I need because there's many different types.

Here's a simplified schematic showing the Xover

The pedal uses relays to do the switching but I know very little about relays so, for now, I'm just going to use a switch. Maybe you could help me out with that too. The schematic shows the secondary of the transformer going straight to the relay coil so I don't think that's right to have AC on a relay coil. I think that relay on the schematic repersents to a self contained "relay unit" which has all the circuitry so you just hook it up to the low voltage AC. I'll try to redraw the whole circuit because it's drawn kinda confusingly.

[bigsbybender]

Leslie almost always used iron core in their crossovers... this would be no exception.

I've done many Leslie Crossover copies

I use these: http://www.parts-express.com/18-gauge-laminated-core-inductors.cfm



j.

[jeff]

Thanks so much! I've been driving myself crazy searching.

 What value do you use? the schemetic says 1.2mH but I don't know where that came from. It's not on the original schematic.

 I used an online crossover calculator and 1.2mH doesn't seem to mate with the 200uF cap to leslie speaker unless the main speaker is 2 ohms. The leslie speaker is 4 ohms so it's Xover point with the 200uF cap is 200Hz. According to this, to get 200Hz on the main you'd use 3.18mH(4ohm) or 6.37mH(8ohm). http://www.diyaudioandvideo.com/Calculator/XOver/

What did you use?

[TubeGeek]

Jeff,


How did your project go?


I am tackling the same thing with my Leslie Model 16 cabinet that I have had sitting around for nearly 10 years without using it.