Reverb only in one speaker - Lexicon MX200 effects unit (with )

The MX15R has a clean and overdrive channel with a common input. The reverb is between these input channels and the power amplifier. The common link between the two, is the input jack and selector switch which chooses which pre-amp section to use. I would check out this switch and jack as most likely, one of the other is open.

Here is a link to the schematic drawing
http://www.prowessamplifiers.com/schematics/fender/ps160.pdf

items to check are
1-the footswitch and plug
2-the reverb unit ,usually found at the bottom of the box
3-the reverb unit is plugged in to the amp
4-V6 a 7025 valve
5- the reverb switch is in the on position

Hope this helps

Len

Make sure you are using BALANCED interconnection cables to the speakers, either XLR or TRS connections. ALSO make sure all interconnected equipment such as the speakers AND the mixer are powered from the SAME receptacle at the venue... yes you have to run extension cords... the pro's do it so they don't have hum and other noise and don't damage their equipment.

Not sure of how it is feeding back. Two possibilities... the reverb tank in the cabinet is no longer shock mounted. The other is your guitar can "hear" the speaker... make sure you are away from the amp. With the reverb on, the feedback stability is less than with it off so make sure your guitar is away from the amp. Acoustic guitars are more sensitive to this than solid body ones.

Do you have the speakers connected properly?? If so, maybe speaker wiring needs checked.

Usually delay is associated with "reverb" not echo. If you are in a large room, the room acoustics can add reverb without the benefit of signal processing.

Reverb NORMALLY passes the inout signal as is and then adds in a delayed version on top.

The delay should be less than the room size delay.

Try turning off all effects as a start. There is some "transport" time if it goes through a digital signal processing.

I suspect the vibration when it is loud is vibrating a reverb tank within the unit.

Test this bylistening with headphones and see if you get same sound.

It may be the reverb has a resonance or the cabinet does that is sensitive to your E chords.

The shock mounting of the reverb may have failed to isolate the reverb tank from speaker vibrations... hence the headphone test.

Blown speaker NO (would not get sound at all)

Bad Reverb UNLIKELY (controls would deselect reverb and it would be out of circuit)

Bad preamp tube NO (controls have no effect)

Bad rectifier and/or filter caps LIKELY

Bad power amp POSSIBLE

SOMETIMES the handle screws must be removed as well.

I have taken a lot of these out and the key is to figure out which direction it comes out... MOST are out the back and sometimes a board across the back has to be taken off with four screws to clear a transformer.

FIGHTING getting the thing out when it catches on the Tolex covering is the USUAL problem. Takes patience and sometimes a blade to hold the Tolex back.

USUALLY the speaker baffle stays in place.

Here is an article that might help:http://www.guitarplayer.com/article/reverb-troubleshooting/jun-09/97165 Here is the schematic:http://www.fender.com/support/amp_schematics/pdfs/Hot_Rod_DeVille_Schematic.pdf Check to see if someone hasn't reversed the input and output cables at the reverb tank. Then troubleshoot the reverb section .