Adding Better Speaker Terminals

Adding Better Speaker Terminals

March 8, in Do It Yourself

I dislike spring clip terminals on speakers and amplifiers, much preferring the better contact and cable retention of good binding posts. Here on my workbench is an Onkyo M-5150 Power Amplifier, but the same modification can be done to other amplifiers and receivers if there is enough room on the back panel.

Adding Better Speaker Terminals

Adding Better Speaker Terminals1

There are several ways to approach this. One way would be to remove the entire terminal block and fill the large rectangular hole with a piece of ABS or sheet metal. A filler piece can be made larger than the hole, drilled for the mounting posts, mounted on the inside, then attached to the chassis back panel with screws or pop rivets.

But in this amplifier, the speaker terminal block also supported the end of the circuit board. I was feeling lazy, and there was plenty of room on the back panel, so I simply drilled four holes and installed Dayton 5-way Binding Posts from Parts Express. Then it was a simple task to solder jumpers from the original A Speaker terminals to the new binding posts.

Adding Better Speaker Terminals2

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Anyone who has drilled sheet metal with a bit larger than 1/16 inch knows that just as soon as the bit breaks through, it grabs and runs through. If you are not careful you can damage internal components. Also, with the larger bits, the sheet metal distorts so that it is no longer flat.

I use these sheet metal cutters that work like a “hole saw.” They are called Rotabroach Sheet Metal Cutters “11,000-series,” and they are from Hougen Manufacturing. They have a little center guide that retracts against a spring as you make contact and drill.

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Another problem with drilling chassis holes is that the metal cuttings can fall into the circuit board and cause the magic smoke to be released. The easy way to prevent this is to simply turn the equipment upside down when drilling or grinding. The cuttings then fall out harmlessly.

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It took just a few minutes to solder jumpers from the original speaker terminal block to the new binding posts. I also applied a little gel type CA glue to the binding post nuts so that they will stay tight.

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For a finishing touch, a label was printed on silver tape. Even though I know what those four posts are for, someone else may need to know. It doesn’t hurt to mark them.

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Now the modified amplifier or receiver may be used with heavier speaker cables equipped with a variety of termination methods banana plugs, spades, etc. I don’t worry about speaker cables being pulled out when dusting behind the stereo cabinet, or when speakers are moved.

Also, I don’t try to keep equipment “all original.” I like it to function well. After all, it is about enjoying the music, right?

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2 comments

  1. hank_in_formosa March 3, at 10:48 am

    Thanks for this helpful writeup, which offers an alternative to boarding up the gaping hole that was the spring-clip module. I think most people would consider this hack an upgrade.

    Now since I am hardly a DIYer and know little electronics, I am wondering what would happen if you tried to output from both the binding posts and the spring clips?

    reply
  2. PaulP May 27, at 7:59 am

    You’d be driving the two sets of speakers in parallel, which would alter the impedance the amp “sees”. Depending on the amp, that could be a Bad Thing(TM).

    reply

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