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I'm working on an art installation where the speaker wires are made of a copper fabric material, a relatively high resistance material. I understand this is not ideal for speakers, but due to aesthetics, I'm trying to see if I can keep this same material without compromising quality/efficiency and the life span of amplifier/speaker.

This is a stereo system and audio's spatial effects are very important. Currently, the sound output is fine, it works with no issues, however, one speaker seems quieter than the other. The speaker's fabric wires are of different lengths, thus I'd like to 'balance' the resistance so both speakers have the same power distribution.

The amplifier is a typical PAM8403 stereo class D amp and its powered by 5V. The speakers are rated 3W 4Ohms.

These are the readings I get from a multimeter (amplifier to speaker connection):

  • Speaker 1+ = 2 ohms
  • Speaker 1- = 1.5 ohms
  • Speaker 2+ = 3.9 ohms
  • Speaker 2- = 4.8 ohms

And if I place the probes in between + and - near the amplifier connections:

  • Speaker 1 = 6.5 ohms
  • Speaker 2 = 12 ohms

The second speaker has a much longer fabric wire, thus the higher resistance. I understand PAM8403 is rated for 4ohms speakers, but would it be OK for it to drive 12ohms?

And to balance the resistance, could I add a 5W resistor in series for speaker 1? What would be best, to add 5.5 ohms on the + line for a total resistance of 12 ohms, or would I need to add resistors to + and - lines, for both speakers, so everything is balanced?

Thank you in advance.

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    \$\begingroup\$ Yes, just add a single 5.5-ohm, 5 watt resistor in series with one of the leads to speaker 1. There's no need to worry about "balance". \$\endgroup\$
    – Dave Tweed
    Aug 11 at 10:46
  • \$\begingroup\$ yes or double up the fabric wires to speaker 2 to halve their resistance. \$\endgroup\$
    – Jasen
    Aug 11 at 12:39
  • \$\begingroup\$ thanks both, I think I will go with the resistor solution as I can't change the length of the fabric wire. Will the pam8403 be fine with 12ohm resistance? \$\endgroup\$
    – Chu
    Aug 11 at 12:45
  • \$\begingroup\$ @Chu what Jasen meant is that you could run two (four) wires to the second speaker to halve resistance. (Not changing length, just running double "thickness".) \$\endgroup\$
    – JYelton
    Aug 11 at 17:17
  • \$\begingroup\$ @JYelton thank you, I see now. But still, that's not possible, there is no more space for wires there. The resistor will do alright! :) Thanks. \$\endgroup\$
    – Chu
    Aug 11 at 18:50
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One option would be just to adjust the gain of your audio amp so that the left and right speakers are balanced.

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