Connected Amp to Logitech Z-680s - Bad Idea? - diyAudio
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Old 2nd October 2007, 10:01 PM   #1
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Unhappy Connected Amp to Logitech Z-680s - Bad Idea?

Hi knowledgable diyAudio folks. I thought maybe someone here in their infinite tinkering wisdom can help me out.

I have a Primare Integrated Amp (75W - that I got about 2 weeks ago. I'm saving up to get a nice Seas or Vifa kit to build so in the meantime, I dug out some old Logitech Z-680 satellites from a computer speaker set. These are rated at 10 kOhm and I plugged them into the Primare without a thought.

Everything worked fine until last night. I turned on the amp and pop/crack sounds came from both channels. I thought i might have been the source (going from computer optical > ART D I/O > Amp) but I plugged in a dvd player with RCAs and got the same result. What's worse is that the volume doesn't do anything on the amp.

Did I kill the amp with the wrong speakers? Or did the amp just break on me? I bought this used so Primare won't cover any repairs. =(
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Old 3rd October 2007, 10:06 AM   #2
jaycee is offline jaycee  United Kingdom
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Location: Norwich, UK
You've probably toasted the speakers.

You need to check with some decent speakers, really. If you are lucky, the amp will have a protection system against dead speakers, and will have survived.
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Old 3rd October 2007, 03:15 PM   #3
gni is offline gni  United States
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I would suspect that the powered Logitech Z-680 satellites fried on
their own. The Primare Integrated Amp was driving them with
the preamp out which would drive a 10kohm load well. Just a case
of overdriving.

The preamp outputs are most likely capable of 5V to 8V which would
be a big amount for little computer speaker inputs designed for
small signal sources. If the volume on the speakers was set to
low, then more preamp voltage would be required at the inputs
of the powered speakers.

Test the speaker outputs first: voltmeter on DC. . .there should
be some DC offset 5mV to 50mV. Then set the voltmeter to AC. . .
play a souce and increase the volume. . .the meter should move. . .

IF you somehow connected the main outputs from the integrated to
the 10kohm inputs. . .they would play very loud with very little volume
control. . . and would distort and crapout very quickly.. . most unlikely.
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Old 5th October 2007, 06:41 AM   #4
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Join Date: Oct 2007
Default A New Discovery! Volume Pot Controls Static

In my testing, I found that adjusting the volume control is changing the nature of the static. At 0, the sound is loud (even though it's supposed to be silent) but as I turn up the volume, the static changes. At level 8, the sound is low but static free. As I turn, some levels it's completely silent others it's popping and crackling.

Any ideas?
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Old 5th October 2007, 02:01 PM   #5
gni is offline gni  United States
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computer optical > ART D I/O > Primare input > Primare Preamp out > Logitech Z-680 satellites. That was your originally setup. Have
you checked the DC offset. . . multimeter on (+) and (-) terminals.

You're sure it's the Primare. . .have you plugged in the Logitech Z-680 satellites to the source directly. . .I'm sure you have. . . just thinking
out loud.

Only two weeks old. . .take it back for warrenty.

The ART D I/O has a hot output. . . could have damaged the input
circuit of the Primare. . .there are suggestions of using voltage
dividers on the output of the ART D I/O. . .but to work as well as
it did then just die. . .it might have been time for early component
breakdown. . .warrenty?
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