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I have built new loudspeakers and now it seems that one of them breaks my amps. I do not know very much about electronics so I do not where to start. Is there a common/well-know fault that causes the (pre)amp to break when building your own loudspeakers?

I have built the filters myself. I have tried the speakers on 3(!) amps and they are broken.

There is no shortcut in the loudspeakers. The resistance is about 7 ohms. It works fine for some minutes but suddenly it does not work on the left channel.

My guess is that the preamps are broken: Two of the amps/receiver work fine when the internal tuner is used but not when I try to connect the CD. I thought that you would break the power amp and not the preamp when doing something wrong (Shortcutting the cables, filter). Also I thought the fuses would save me.

I tried with headphones and the result is the same: The left channel is broken.

Regards Mikael
Things like this are difficult to diagnose long distance.
Some random thoughts:
--I find it difficult to imagine a way that a speaker can cause a preamp to malfunction. If you're using a preamp and amplifier combination rather than an integrated amp, and are saying that the preamp channel is dead (rather than all three amplifers--I'm not clear from your post what is working and what is not), then it's probably just a coincidence that your preamp died at about the same time that you put new speakers into your system.
--There could easily be an intermittant short in your speakers. Some shorts will open the circuit, which would lead to no sound, but no damage to the amplifiers. Other shorts will cause the + and - leads to feed together, which could cause an amplifer channel to die. You might want to take a look at the wiring inside your speakers, particularly the crossovers. If two wires are close enough that they might touch, you could have a short.

Thanks for the answer. From my point of view I also find it hard to break the premamps and maybe I'm looking at the wrong part. I have changed all parts including the loudspeaker cables and it seems that one speaker is causing the trouble.

I have tried:
1. One preamp together with a poweramp.
2. Two integrated amps.
3. Changing cables.
4. Changing cd-player.

The filter in the loudspeaker consists of two parts. One low pass filter with a recistance of about 7 ohms. The highpass filter can not be shortcutted since there are 2 capacistors in serie with the tweeeter. Maybe this part can cause strong currencies to run through at high frequencies.

One more question: Can a shortcut after the poweramp cause the preamp to break down? The whole story started with a shortcut ( two banana contacts shortcutted each other at the loudspeaker) and the fuses burned in the power amp.

I can have a look at the loudspeaker. But how do I verify that the change is correct? Do I have to burn preamps until I find the error? A more sophistcated way of testing should of course be better.
If you shorted an amplifier output and blew the fuses, that alone would be sufficient to destroy some amplifier designs.
Some of what you're saying seems contradictory, so I'm having trouble understanding what has happened. It might be best if you got someone to look over your stereo in person to determine what is going on.

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