Bridge Tied Load , Class D amp

I'd forgotten the double wound toroid inductor of 360uH in series either side of the speaker. What sort of value of inducance for L1 and its wire gauge/current carrying requirement for 300 to 600W use? C may be about 1uF

No, that will toast the switching stages.

You could eliminate the filter and drive the speaker directly, but it would radiate EMI like gangbusters.

John

W

I forgot the 2 x 360uH, one either side of the speaker then in parallel with the L and C. Also shielding around the L, would it be an EMI radiator then ?

This is on a recent amp , Ampeg BA600-115

I removed the filter cap to measure the inductance of L1 . Cap marked 1uF,

250V. This L1 weighs about 170 gm, estimating weight of remainder components and pcb from total of 290 gm. Through a hole I can see some wire about 1mm diameter. Using 1KHz RLC meter, L1 measures -2.2H on H scales and -140mH on mH scales, don't know what that means , will try and find a manual for an Avo B183. Maybe faulty, but measuring plain inductors through the scales is positive and consistent across neighbouring scales. 1KHz ac resistance is 230R, DC resistance is 4K so perhaps what is labelled as L1 is R and L in series. Perhaps R of 4K and L of .6H , to give 230R at 1KHz, but if wholly 1mm wire I cannot see how 600mH with 170gm of 1mm wire, strange core material?

I seem to think there is capacitance in parallel with this thing. Have you disconnected the inductor (or is it a transformer or a tapped inductor?) to the extent that no more than one lead remains connected to other circuitry? Negative inductance readings make me think capacitance.

DC resistance of 4K and lower AC resistance makes me think of a capacitor that has a 4K resistor in parallel with it, though an inductor may be in there also.

--
 - Don Klipstein (don@misty.com)

1uF,

and

scales,

positive

labelled

wire

I could not find a manual for the B183 or B184 . I tried an audio output transfrmer and a resistor but no negative readings on the meter. Perhaps there is another capacitor inside the can , other than this external 1uF that I removed temporarily.