I lost the treble on both Alesis Monitor 1 speakers. The treble is good on the amp output toward the speakers. I'm thinking they went out one at a time and I didn't realize it until I lost the 2nd one. Could it be the circuit board in each? If so, can I purchase two of them?

First and formost check the connections and ensure no stray strands between cables are touching, also the surface of the speaker is not been damaged

Crossovers RARELY blow... most likely the tweeter speakers have blown... not fun to find replacements.

If you don't know how to connect this... well we don't either because you did not tell us what your sound system is. The larger plug is what is known as a "Speakon" connector and is a fairly reliable speaker connection that is used now. For your use you will PROBABLY use either of the 1/4 inch jacks with a cable from the amp that will drive the monitor(s). If you have multiple monitors you will daisy chain them using the 1/4 inch jacks and SPEAKER rated cables creating a string of speakers with input going into one and an output from the same one to the next speaker and so on...USUALLY you will be limited to two speakers per amp output...

Hi,

I don't think that there's anything wrong with the amp.
I'll think you're using a x-over, connected to the low-output.

Just a shot,
Gerard

You can without an amp in between. They are non-powered speakers and need an amp to drive them. If you connect your laptop to a mixer, mixer to an amp, then amp to speakers THEN they will work.

To test speakers get a 1.5 volt battery and put the (-)wire of the speaker to the negative end of the battery. Then take the + wire and for a split second touch the positive terminal of the battery. You should hear the speaker pop! Listen to each unit inside the speaker, any that don't pop are not working.
If you look inside the amp you may see that something has burnt up. Look carefully at whatever is on the heat sink.

Hi, Email Alesis and ask very nicely and they might email you a copy of the schematics, which also has the parts listed, etc.

I had the problem of the blinking LED's a few years back, really odd, and fixed it, and now I do a search and all I can find is people with the same problem or similar. Depending on how bad the damage is, it should be repairable unless its done extensive damage to the PCB board. PCB boards are still available to buy, dont bin it, they are too good to be binned ;)

Hi arda5
Did you try swapping speaker connections left for right on the back of the amp to isolate the problem. If the fault stays with the speaker, then that is where your problem is. Try this and get back to me here with the results.

regards
robotek

Hello!
my speaker Alessis M1 Active 620, with a roar is very strong in the speaker, the potentiometer does not attenuate, change the volume. Ja switched capacitor C8, based on my research of other users, but got no result. When you press the power button, the LED lights in blue, and even change the color to red, producing a noise (snoring) very strong.
help!
Please help me!

Hi again andrew63,

There are two possible methods of adjusting the bass and treble output to your Logitech R20 speakers:
1. Hardware - if you feel like experimenting or working with electronic gadgets, you can connect an external preamp with tone control or graphic equalizer between the PC and the input of the speakers/amp; and/or (probably the easiest)
2. Use a software (to listen to your music files/medium) that has a virtual equalizer such the old MusicMatch Jukebox or as an add-on/plug in.

Btw, thanks for asking me to be a Tech Buddy.