VOGONS

Altec Lansing ACS450 Hiss

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First post, by BootyNugget

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Hi everyone --

I have had a pair of these Altec Lansing ACS450 speakers sitting around for years, but never used them due to the quite loud hiss they make when they're sitting idle. It's so loud that it's even audible when sound is playing! My question is:

Has anyone figured out what causes this with this specific model? I know it's super common with these and it even happened when they were new, as they were a Gateway 2000 OEM and Gateway actually offered a slight refund and a set of the shorter ACS400 speakers if you called in and complained, if I'm remembering correctly.

I have had them apart and I don't see any obvious signs of damage - blown caps, etc.

Thanks in advance for any info anyone can provide!

Reply 1 of 2, by Tiido

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The low end amp chips used in these kind of speakers tend to be noisy and often have gain set very high which only makes the hiss greater.

It may be possible to change the feedback resistors to be metal film types and also reduce gain while at it (but not below a minimum gain figure that many amps have, or they'll oscillate etc.). I have made several old amplifiers dramatically less noisy that way.

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Reply 2 of 2, by BootyNugget

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I'll look into that! I have a pair of ACS500 units as well, which look the same. I suppose I could compare the PCBs between the two units and see if there are any glaring differences.

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