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Topic: What happens when the amp in powered speaker stops working? (Read 4917 times) previous topic - next topic
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What happens when the amp in powered speaker stops working?

Hi all,
If the built in amp in a powered speaker stops working, can I still use the speaker with an external amp or does the speaker become unusable?
Thank you

Re: What happens when the amp in powered speaker stops working?

Reply #1 –
Well, you'd be putting that power through a dead amplifier, not very likely to work at all well.  The active crossovers won't be active and you might pump way too much through the tweeter and fry it.  Or the dead amp might just act as a big resistor and you won't hear anything.  I wouldn't try it.  Without the amp an active speaker isn't a speaker anymore.

But someone with more technical expertise than me may disagree.
Ed Seedhouse
VA7SDH

Re: What happens when the amp in powered speaker stops working?

Reply #2 –
Quote from: Invisible77 on
Hi all,
If the built in amp in a powered speaker stops working, can I still use the speaker with an external amp or does the speaker become unusable?

It becomes unusable unless you remove the dead amp and hook an external in its place. 

Re: What happens when the amp in powered speaker stops working?

Reply #3 –
It's possible to still use it with an external amplifier, but you need to put a passive filter/crossover in the speaker with the right parameters.

It's easier to fix the active amplifier. In most cases there is just one part defective like a capacitor or a fuse.
A fuse is the most easy to fix.

Never connect a tweeter with the proper filter, you will blow it.

Re: What happens when the amp in powered speaker stops working?

Reply #4 –
Quote from: Fairy on
It's possible to still use it with an external amplifier, but you need to put a passive filter/crossover in the speaker with the right parameters.

It's easier to fix the active amplifier. In most cases there is just one part defective like a capacitor or a fuse.
A fuse is the most easy to fix.

Never connect a tweeter with the proper filter, you will blow it.

IME that is the best way to go.

Rule number one in trouble shooting is that power supplies are still among the least reliable circuits in *anything*.

If not that, then the output stage.

If the amp uses a switchmode power supply it may be hard to troubleshoot, especially without a detailed schematic. There are a large number of off-the-shelf switchmode power supplies with various ratings, and amazingly low prices.  eBay may be your friend.

The circuitry often has an obvious splice  between the power supply and the power amplifier, and  you  take advantage of this. The powered speakers enclosure can conceal a lot of potentially ugly but technically effective substitutions!  Just try to keep the power supply's output capacitor represented in the circuits.

It turns out that the amp designs in powered speakers seem to tend to be chosen from a short list, and even if you can't find a scematic for the amp(s) at hand, you may find a schematic for a similar one. For example a lot of powered speakers use off-the-shelf chip amps, and the application notes for the chip may not be a bad guide for the mystery amp before you.

And that gets you to another work-around. There are a large number of pre-built power amps that may strongly resemble the power amps in the active speaker. the crossovers generally tend to be more reliable. It is generally easier to discern signal routing then actual operation of power amp circuits, so substituting in an off-the-shelf power output stage is another despirate but workable solution.

Re: What happens when the amp in powered speaker stops working?

Reply #5 –
I made a typo "Never connect a tweeter without the proper filter, you will blow it." off course ;)

With a defective active speaker you have the other speaker most of the time in good condition. Someone with more technical knowledge could be able to take measurements to find out the defective part, or even exchange parts to find the culprit.

I'm not entirely sure, but when you replace the power supply, should you replace both then? When you put a new an possible bigger and more stable powersupply in one speaker could they sound different after that?

I could be wrong, but personally I would like to keep those the same at both sides. A bit like running the left channel via a tube amp and the right channel via a solid state amp, well there I would be exaggerating it a bit ;) It's 'just' the power supply after all...

Re: What happens when the amp in powered speaker stops working?

Reply #6 –
Quote from: Fairy on
I'm not entirely sure, but when you replace the power supply, should you replace both then? When you put a new an possible bigger and more stable powersupply in one speaker could they sound different after that?

No. As long as both power supplies deliver adequate power and don't have any obvious defects such as noise, the speakers will sound exactly the same.

Re: What happens when the amp in powered speaker stops working?

Reply #7 –
Quote from: Fairy on


I'm not entirely sure, but when you replace the power supply, should you replace both then? When you put a new an possible bigger and more stable powersupply in one speaker could they sound different after that?

I could be wrong, but personally I would like to keep those the same at both sides. A bit like running the left channel via a tube amp and the right channel via a solid state amp, well there I would be exaggerating it a bit ;) It's 'just' the power supply after all...

No, and no.

100% confirm and support the previous post about not worrying about the power supply

Despite the current placebophile excitement over power supplies, other than keeping the current coming power supplies are the most generic part of any piece of audio gear, and most audio gear is actually pretty generic.  I can give you a list of reasons why using a SS amp on one channel and a Tubed amp on the other is a bad idea starting with the fact that due to the probable relatively high source impedance of the tubed amp, it is likely to really sound different. The power supplies are generally vast overkill due to US Govt regulations relating to power amp power ratings.  All power supplies are buffered from the audio signal by the circuits they power, so at best their effects on sound quality are second or third order, or if you will twice or thrice removed.

Besides, IME a lot of powered speakers pack all the electronics into one of the speakers, so there is actually only one power supply in those cases.