GB Shuttle 6.0 - lost tube section

[fyziqs]

Greetings,

During the third song into an hour set last night, my bass rig stopped making sound! I quickly determined it was the tube section of my Shuttle 6.0 - I typically run the amp with a mix of tube and solid-state, and switching to just the solid state channel brought the rig back to life. Switching to pure tube or mix resulted in very, very low signal. On a side note - so glad this two-channel amp was there to save me during a gig!

What, in your professional opinions, could be the root cause of this? Is this a dead or dying tube? Bad turnpot? Thanks in advance!

 

[BassmanPaul]

The obvious first step would be to replace the tube, probably a 12AX7/ECC83. If that doesn’t work page @agedhorse for a definitive answer.

 

[agedhorse]

Assuming this is a ShuttleMax 6.0, before replacing the tube, try using a short cable patched between the tube channel's effects send and return. If that doesn't fix the problem, try replacing the tube. If that still doesn't fix the problem, PM me and I will get you information on getting your amp serviced.

 

[fyziqs]

BassmanPaul - thanks for the suggestion. If I have to go with a new tube, I will get the one you suggest.

Assuming this is a ShuttleMax 6.0, before replacing the tube, try using a short cable patched between the tube channel's effects send and return. If that doesn't fix the problem, try replacing the tube. If that still doesn't fix the problem, PM me and I will get you information on getting your amp serviced.

I will start with the short patch between send & return - I will report back! Thanks!

 

[fyziqs]

Assuming this is a ShuttleMax 6.0, before replacing the tube, try using a short cable patched between the tube channel's effects send and return. If that doesn't fix the problem, try replacing the tube. If that still doesn't fix the problem, PM me and I will get you information on getting your amp serviced.

Update: I hooked up the amp to my rig, powered it up, and both solid state and tube sections appear to be working just fine, at least at low volume. This is great, but unnerving. Not being able to reproduce the problem makes it difficult to trouble shoot! I will try again at 'show volume' to see if I can replicate the issue. If/when I can reproduce the issue, I will try the effects loop send/return trick and report back.

 

[BassmanPaul]

Update: I hooked up the amp to my rig, powered it up, and both solid state and tube sections appear to be working just fine, at least at low volume. This is great, but unnerving. Not being able to reproduce the problem makes it difficult to trouble shoot! I will try again at 'show volume' to see if I can replicate the issue. If/when I can reproduce the issue, I will try the effects loop send/return trick and report back.

This is a typical Effects Loop symptom. It’s not just your amp that suffers from loop problems. Many players just leave a short signal cable in the jacks, like for linking pedals. Listen to agedhorse as I’m pretty sure he designed your Shuttle.

 

[fyziqs]

It’s not just your amp that suffers from loop problems.

Can you elaborate on this point?

I'm definitely listening to agedhorse! I put a jumper into my amp bag to try next time this occurs.

 

[agedhorse]

Can you elaborate on this point?

I'm definitely listening to agedhorse! I put a jumper into my amp bag to try next time this occurs.

This is not uncommon on all amps that contain an effects loop. The switching contacts for this function are open to the elements and vulnerable to such problems.

 

[fyziqs]

This is not uncommon on all amps that contain an effects loop. The switching contacts for this function are open to the elements and vulnerable to such problems.

Thank you, agedhorse - I see why this is somewhat common for amps with effects loops.

 

[BassmanPaul]

The jacks for Effects Loops have switches attached that are supposed to pass the signal when the loop is not being used. These, especially those loops that are not usually used, can corrode and then cut out the signal intermittently. The cure is to clean the switches with Deoxit #5 contact cleaner. This is not as easy as it sound because the switches are hard to get at without taking the amp apart. Joining the jacks with a signal cable effectively bypasses the switches and their associated problems.

 

[agedhorse]

Often it's just a bot of dust or microscopic oxide layer that interrupts the signal. Cycling the plug in and out oft he return jack a few times often clears the problem too.

 

[fyziqs]

The jacks for Effects Loops have switches attached that are supposed to pass the signal when the loop is not being used. These, especially those loops that are not usually used, can corrode and then cut out the signal intermittently. The cure is to clean the switches with Deoxit #5 contact cleaner. This is not as easy as it sound because the switches are hard to get at without taking the amp apart. Joining the jacks with a signal cable effectively bypasses the switches and their associated problems.

Thank you both for the info! It is most helpful.

 

[rodl2005]

Often it's just a bot of dust or microscopic oxide layer that interrupts the signal. Cycling the plug in and out oft he return jack a few times often clears the problem too.

Yes. Had this problem, and this routine fixed it. Great lil amp that Shuttle. Enjoy