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Post by jj2106 on Mar 13, 2018 4:28:00 GMT -5
Hello all,
My question more specifically concerns the Basx-A500 and A-800, but is more general.
If I use, say, 4 channels of the A-500, is it a good idea to short-circuit the input of the fifth channel?
Thank you,
Jean-Jacques
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Post by Gary Cook on Mar 13, 2018 5:13:18 GMT -5
Unnecessary.
Cheers
Gary
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Post by Porscheguy on Mar 13, 2018 9:58:08 GMT -5
Unlike some tube amps, SS amps do not require a load. You can run it with nothing hooked to the outputs.
I should also add that you shouldn't drive the input stage of those channels with a signal, especially at high levels.
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KeithL
Administrator 
Posts: 10,261
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Post by KeithL on Mar 13, 2018 10:55:41 GMT -5
Absolutely correct.... None of our amplifiers will be damaged by being run with nothing connected to some of their inputs or outputs. There are, however, three qualifications there: 1) In some rare cases we've seen amplifiers go into protect occasionally on channels where the input was unconnected. An unconnected input can pick up noise, which can trigger the protection. It won't hurt anything, but, if it happens, shorting the input will prevent it. (I absolutely wouldn't bother unless you're one of the very rare cases that has this issue.) 2) The noise floor on most amplifiers is a tiny bit lower if the input is terminated. So, if you have a channel with nothing connected to its input, but with a speaker connected to the output, you may notice a slightly higher noise floor on that channel.. Shorting the input will lower the noise floor to equal, or be slightly lower than, the noise floor on the other channels.. 3) Virtually all solid state amplifiers will have no problem being run at normal levels without a speaker connected. However, CERTAIN amplifiers may be damaged if you apply a HUGE overdrive to the input with no speaker connected. If you do that, you may succeed in overloading the internal driver stages, which can eventually damage them. (So cranking the volume all the way up up on a channel whose input is connected, without a speaker connected, "just to see what happens", isn't a great idea.) Unlike some tube amps, SS amps do not require a load. You can run it with nothing hooked to the outputs. |
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Post by Loop 7 on Mar 13, 2018 11:41:19 GMT -5
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Post by Loop 7 on Mar 13, 2018 11:42:14 GMT -5
I'm only using 3 out of 5 channels on my amp.
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Post by jj2106 on Mar 13, 2018 13:11:17 GMT -5
I like the idea of the noise-stopper caps, but they are sold by 10 and expensive.
I think I'll use ordinary RCA plugs with a touch of solder
Thank you everybody anyway
Jean-Jacques
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KeithL
Administrator
Posts: 10,261
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Post by KeithL on Mar 13, 2018 17:15:52 GMT -5
They do also keep out the lint and the dust bunnies.... and may even slow down oxidation a bit. |
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Post by RichGuy on Mar 13, 2018 20:17:34 GMT -5
I use noise caps on my unused inputs/outputs. You can find them pretty cheap on ebay. Here's a link for 10 RCA caps for $9.99 includes shipping, There are other options on ebay to buy more or less, like 20 for $14.99 if you search RCA caps. link Attachments:
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Post by kybourbon on Mar 13, 2018 20:56:35 GMT -5
What kind of wizardry is this?!??
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KeithL
Administrator
Posts: 10,261
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Post by KeithL on Mar 14, 2018 9:38:23 GMT -5
I should note something here.... There is a difference between a "cap" and "a shorting plug". A shorting plug is an actual RCA plug whose center pin is tied to its ground (it HAS a center pin that goes into the connector). A shorting plug will often lower the noise floor slightly because it electrically shorts the input SIGNAL to ground (which only really matters if you have a speaker connected, but no input). (There are also plugs that apply a 1k load rather than a short... which does pretty much the same thing.) A CAP that simply covers the outside and top of the connector, but which does not include that center pin, will NOT have the same effect of lowering the noise floor. It will help keep out dirt and dust, and may reduce oxidation, but it will not generally lower the electrical noise significantly. So..... All shorting plugs are also caps... But not all caps are shorting plugs... I use noise caps on my unused inputs/outputs. You can find them pretty cheap on ebay. Here's a link for 10 RCA caps for $9.99 includes shipping, There are other options on ebay to buy more or less, like 20 for $14.99 if you search RCA caps. link |
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