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PostPosted: Fri Jan 01, 2016 1:13 pm 
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Bottle Rocket

Joined: Fri Jan 13, 2012 10:56 am
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I'm running a stereo rig with 2 Mesas, a TA30 and a MiniRec. My pedal board is a bunch of fuzz, boost, and OD pedals into a Diamond Halo Chorus, which splits stereo into the amp inputs. From there, I run the effect sends from both amps into a Strymon Mobius, Timeline, and Big Sky, then stereo out from there into the effect returns on both amps.

This rig sounded amazing until last week. I tore my pedal board apart and replaced a bunch of cables as I reconfigured everything. Now I have a crazy loop issue I don't understand.

When I run the TA30 on the blue channel, it still sounds like it should. But the MiniRec seems to be putting out a 100% wet signal. When I switch off the MiniRec's loop, I get no sound from that amp with no impact on the TA30. When I switch off the TA30's loop, it kills the sound to the MiniRec as well.

When I switch the TA30 to the red channel and run it in tweed mode, or any of the others, both amps sound fine and perform as they should.

I bought and returned two different TA30 combos when they first came out, both for loop problems. I swore off that amp due to the poor loop implementation, but never got over how much I loved the top boost tone. I picked up my current TA30 head a few weeks ago, and it seems to have the same or a similar problem. It's probably an early example.

Before I walk away from this amp forever, has this been identified as a problem by Mesa and fixed? Is it just me?


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PostPosted: Fri Jan 01, 2016 4:05 pm 
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Are you switching via midi program, or using the amp's foot switch?

The way I read it it sounds like a problem with the configuration of one of your pedals. When you're in the red channel it's in mono in/stereo out, and in the other channel it's stereo in/stereo out.

If you're not switching via midi then I have no idea.

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Ignore the hype and trust your ears. Play more, buy less = better tone.

|| J-Bass | Strategy Eight:88 | PH410 ||
|| Les Paul-McCarty-Telecaster | Dual Rectifier | Recto 4x12 ||


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PostPosted: Fri Jan 01, 2016 5:06 pm 
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Bottle Rocket

Joined: Fri Jan 13, 2012 10:56 am
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I am switching using the amp's foot switch. I'd love to believe it's a pedal problem, but I get the same results when I use only my Supernatural through the loops and avoid all of the Strymon stuff.


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PostPosted: Fri Jan 01, 2016 6:51 pm 
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Is there an increase in background hum (60Hz) when the two amps are connected together?

_________________
Ignore the hype and trust your ears. Play more, buy less = better tone.

|| J-Bass | Strategy Eight:88 | PH410 ||
|| Les Paul-McCarty-Telecaster | Dual Rectifier | Recto 4x12 ||


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PostPosted: Fri Jan 01, 2016 11:47 pm 
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Bottle Rocket

Joined: Fri Jan 13, 2012 10:56 am
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No change in noise when the amps are connected together.

I just ran another test. I pulled everything out of both loops, grabbed my Supernatural reverb pedal, and ran it mono through both amps. No problems with the MiniRec, performed as it should. With the TA30, it was craziness. The amp sounded fine with the pedal turned off, but as soon as it was switched on, the amp emitted a high-pitched screech. At first I thought it was the act of switching the loop on that created the problem, but no. It was stepping on a pedal that worked fine in the loop of my other amp both before and after that test.

Any more thoughts?


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PostPosted: Sat Jan 02, 2016 1:10 am 
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I'd call Mesa and ask them direct.

I suspect the TA-30 has a unique loop design. If I remember correctly, the reason the TA-15 didn't have an FX loop is because it had a post phase inverter master volume (PPIMV). By putting the master after the PI it allowed the preamp to hit the PI at full strength and drive the piss out of it like it would in an AC-30, yet unlike an AC-30 you'd still have control over the volume and could get overdrive at reasonable volumes.

The drawback to this design is that putting an FX loop pre PI is kind of pointless since the signal going into the PI is going to get distorted, and they can't put it post PI as the signal has been split in two to drive the power amp.

With the TA-30 I've always wondered how they implemented the FX loop. But have no info on it. Mesa should be able to give you that info and maybe help you understand why that specific pedal is freaking out.

_________________
Ignore the hype and trust your ears. Play more, buy less = better tone.

|| J-Bass | Strategy Eight:88 | PH410 ||
|| Les Paul-McCarty-Telecaster | Dual Rectifier | Recto 4x12 ||


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PostPosted: Sun Jan 03, 2016 12:35 am 
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Bottle Rocket

Joined: Fri Jan 13, 2012 10:56 am
Posts: 20
So things just got better/worse. I just replaced the loop tube in the TA30, and now the amp just sings. But if I'm hearing this correctly, the loop send from the TA30 is hitting all of my stereo effects really hard, and the return level is very low compared to the MiniRec. The consequence is that the MiniRec winds up sounding like it is 80% wet, and the TA30 sounds almost dry, despite running effects that are perfectly stereo balanced if I run them direct into the amps.

This has to be something wrong with the TA30's loop, no? I can't wait to hear what Mesa has to say about this.


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PostPosted: Wed Jan 06, 2016 11:16 am 
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Bottle Rocket

Joined: Fri Jan 13, 2012 10:56 am
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So here's Trent from Mesa's reply:

The issue that you are encountering is not that the amp has a problem but that it isn’t designed to be used in the way that you are attempting – specifically the TA-30. Because of the two different types of circuits in Ch1 and Ch2 of the TA-30, the Send and Return levels are different for each channel. The Send level is stronger in Ch1 (depending on the setting of the Volume control), so the Return Level is reduced or padded down. If the Ch1 Send signal is “returned” to a different amp that doesn’t have the Return level padded down, the signal will be much stronger in that amp.

This was the only way to incorporate two vastly different types of amp circuitry in one amp—the AC30 style with the Fender style. The bottom line is that the only way to run a stereo TA-30 rig as you’ve intended is to use two TA30s, and have them both switch channels at the same time.


That being said, here's a question. I love the AC30 tones from the TA30, which are really the only reason I bought the amp. The drive channel is great as well, but I prefer what I get from the MiniRec for those purposes. I spoke with Strymon about this, and it seems that the Big Sky sums both inputs together in mono before hitting the reverb machine, whereas the direct signals are passed through in stereo. So if I am reading this correctly, a passive attenuator in the loop after the TA30's send would bring the level down to a point where the reverb input won't be crazy, and all I need to do is turn up the TA30s master to bring things back into line, correct?


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