3-channel dual rectifier fx-loop/solo switch problem

[samaheta1]

Hi guys!

I'm having a little problem using my solo switch. I've tried setting the knobs to LOOP ON and FOOTSWITCH (and I've also tried every possible position for every knob.) and the sound of my amp changes to very treble-ish and the volume drops down to ridiculously low. It sounds like a 10W amp, not a dual rectifier. Even when cranked it's still quieter than with the loop off and channel volume at 9:00. So the solo switch actually works but the overall sound isn't normal when the loop is switched on.

When the fx-loop is bypassed the amp works just fine but when I switch the fx-loop on, the problem occurs, and as we know the fx-loop must be switched on to use the solo-switch.
The tubes are about a year old so I don't think they are causing the problem.
Is there something I'm missing? Any ideas?


EDIT:

Problem solved. Didn't know there has to be a cable between send and return jacks

 

[Shemham]

The tubes are about a year old so I don't think they are causing the problem.
Is there something I'm missing? Any ideas?

I think there's your problem.

The quality of the current production tubes isn't that great in general. It's not impossible for one to go south only after one year. FX loop cathode follower especially likes to eat certain current production tubes. JJ/New Mesa 12ax7 and most of chinese tubes seem hold up there just fine.

So try to switch the tube on V4 position with a known good one and come back if the problem persists.

 

[vick1000]

Is there anything in the loop? Are the send and return levels at 3PM or higher, I like mine maxed out with nothing in the loop. Try cleaning the send and return jacks with Deoxit 5. If there is a spiral filament tube in V4, it's probably dead or dying. I don't think Mesa uses spiral filament tubes, so it would have to be a Tung Sol, Sovtek, or Electroharmonix to be spiral.

 

[samaheta1]

There is nothing in the loop. I got the V4 out. It's a 12AX7-A Russian 2 Mesa tube, looks ok but maybe he is tired and needs to be replaced, I'll buy a new one when I get money..

 

[screamingdaisy]

There is nothing in the loop. I got the V4 out. It's a 12AX7-A Russian 2 Mesa tube, looks ok but maybe he is tired and needs to be replaced, I'll buy a new one when I get money..

The Russian 2 is an Electro-Harmonix 12AX7EH. They used to work great until New Sensor changed the manufacturing specs and they started failing in certain applications (like the Recto's cathode followers). Mesa has since switched to the JJ ECC83.

The two cathode followers in your Recto are in V3 and V4. The Russian 2s should continue to work fine everywhere else.

 

[vick1000]

Make sure there are Chinese (Shuguang/Sino) or JJs in V3 and V4, if you want to stick to Mesa branding, just be sure they are new, not new-old-stock..

 

[domct203]

........... EDIT:

Problem solved. Didn't know there has to be a cable between send and return jacks

That is not normal behavior. You should not need a patch cable at all. Are you sure the amp is not modified?

Dom

 

[vick1000]

Probably dirty jacks.

 

[samaheta1]

........... EDIT:

Problem solved. Didn't know there has to be a cable between send and return jacks

That is not normal behavior. You should not need a patch cable at all. Are you sure the amp is not modified?

Dom

No, I'm not sure. Although the guy I bought it from didn't say it's modified. He bought it in 2010 and told that he only used the loop for a few times. Slight corrosion/oxidation in the jacks, maybe?

 

[deeman]

Did you make sure the send/mix pots on the back of the amp are set at about 12 oclock? The level there may be low which would make sense if you switch to that mode the volume drops.

 

[samaheta1]

Did you make sure the send/mix pots on the back of the amp are set at about 12 oclock? The level there may be low which would make sense if you switch to that mode the volume drops.

Of course I checked. Turning the knobs made no difference without a patch cable.

 

[Nomads]

Sound to like someone has modified the effects loop from parallel to series, that would be one of a few reason for the patch cable in the loop. If you ever open it up take some pics and post them thanks