Hardwiring s.e.x. 2.1 for 8 ohms and balanced output?

Jim R. · 6359

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Offline mcandmar

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Reply #15 on: May 06, 2014, 03:12:12 PM
Makes sense if you never need to switch it over again or use unbalanced headphones.   Are you adding a socket or just going to connect via the speaker taps?

M.McCandless


Offline Loquah

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Reply #16 on: May 06, 2014, 03:33:49 PM
Based on some discussion on a new thread I created about enlarging the hole in the plate, I think I'll stick with an adapter lead from the speaker taps.

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Offline Paul Joppa

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Reply #17 on: May 06, 2014, 04:38:10 PM
...  Don't ask me to work out which terminal on the transformer is which, that would require a few diagrams and lots of head scratching....
Funny, thanks! You have no idea how much head scratching and how many diagrams it took before I could put that simple PC board together - and I designed the #$%^ transformer just so we could do this dance!

For 4 or 8 ohms on the SEX amp, the windings are in parallel and there is no center tap. Balanced lines is short for balanced-impedance, meaning the impedance to ground of each side is the same. So you need an equal resistor from each side to ground.

Paul Joppa


Offline Loquah

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Reply #18 on: May 06, 2014, 04:42:02 PM
...  Don't ask me to work out which terminal on the transformer is which, that would require a few diagrams and lots of head scratching....
Funny, thanks! You have no idea how much head scratching and how many diagrams it took before I could put that simple PC board together - and I designed the #$%^ transformer just so we could do this dance!

For 4 or 8 ohms on the SEX amp, the windings are in parallel and there is no center tap. Balanced lines is short for balanced-impedance, meaning the impedance to ground of each side is the same. So you need an equal resistor from each side to ground.

Sorry to keep asking this, Paul, but does that mean a 100 ohm resistor (for example) from each of the -ve pins to the chassis?

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Offline Paul Joppa

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Reply #19 on: May 06, 2014, 05:04:52 PM
Yes, that's exactly what I meant by "an equal resistor from each side to ground" - assuming you also have a 100 ohm resistor from the positive to chassis ground.

Paul Joppa


Offline Loquah

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Reply #20 on: May 06, 2014, 05:46:46 PM
OK, so there should be 4 resistors in total? One for each contact on the 4-pin XLR?

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