3 channel Triple Rectifier Loop Mod.(Parallel to Series)

[afu]

I do believe the end of the resistor pointing toward the front is the end to lift. If in doubt, just double check the track when you have that board in front of you.

The bleed is inherent to 12ax7 tubes. They're two stages in one tube. If one stage has a large signal on it, it's easy for the other to pick up a little of it.

The reason Modern can be heard is probably related to the negative feedback reducing gain in the power amp of the other modes. All the dirty modes are bleeding through, but the NFB filtering scrubs it out after the fact, because it makes the amp less sensitive to noise.

 

[noiseordinance]

I'm thinking about doing this mod for my Tremoverb. Only thing is I'd really like to keep the effects loop switchable. Earlier in this thread, someone alluded to the idea that the mod allows effects switching to remain intact on the Tremoverb. Can anyone verify if this is true?

 

[DS-1]

A question for who made this mod:

my Triple Recto has the fx loop mod made by desoldering only one wire from the MIX pot.

Is my mod the same as the one on the last posts?

I'd like to understand someone has tried different fx loop mods and also noticed sound differences between the mods, thanks!

 

[BaklavaMetal]

Hello all,
i have a 3ch dual recto on which i modded with just lifting the mix pot wires and jumpering the 2 pads like explained above. But, it doesn't sound good, like someone put a blanket over the box, it's very dark and muddy. I checked the solder joints, they look pretty solid. Tried with few patch cables.
Anyone has an idea? Thank you

 

[BaklavaMetal]

To answer my question:
I had to desolder the switching transistors too, as shown in the pictures in the first post of this thread.
After removing those and jumpering the outer pads (i left the bottom transistor) the amp now sounds like before and i don't hear any issues using TC electronic Nova System in the loop.

 

[Grindr]

I have a mid 90's Dual Rec, and it's been one prob. after another: e.g. the orange and red channels include a crackle sound in them when I record them. I'm gonna try something like a Mooer micro pre pedal; but the Dual Rec can't even take a normal fx return. I may bother to have a tech look at the pre. As it's a three channel, and the parallel fx idea was just stupid anyway (they are series now in the new ones), I take it I need to do the mod given by the first response; at least to judge by BaklavaMetal's posts.

I had some trouble reading the text on the initial two pics of the mod, what with the red text on the red wire, so I puzzled it out and transcribe it here:

Photo 1: "Remove these three wires, and these 3 pronged things" (which bear a curious resemblance to transistors)
Photo 2: "Put jumper wires in the following locations The middle holes should be left open at the top 2 locations And the third row remains empty Leave the left pad Empty where the mix pot wires were and put a jumper Between the middle and right pad"

As to where the mix pot wires were, I believe the same argument applies to them as to the mod where you just make the modification to the wires on the pot: "Mesa Parallel To Series FX Loop Mod." In that mod, however, there is no need to short the middle and right wires, since it just removes the pot from the circuit. You can more easily simply remove the left wire, so the dry signal isn't fed into the return in the first place, and then use the mix pot as a return level pot. Less work that way.

My questions about this are:

1. Am I right, and can I just skip removing the three wires to the pot, and just disconnect one wire to it; and have a return level to boot?
2. Which wire do I remove for the Dual Rec? It was the left one in the linked vid. Maybe I can trace the wire.

For what it's worth: The mod by warpedmusician is virtually electrically equivalent to the mod where you remove one wire from the mix pot, and short the other two; except the mod by warpedmusician is harder and has more steps. Furthermore, it appears there's no need to short the other two wires on the pot. That just takes it out of the circuit, and has extra steps; when you could save yourself the trouble and just use the Mix knob as the return level knob. His whole mod is basically electrically equivalent to removing one wire from the volume pot, taping it, but doing nothing else but turning the Mix pot to 100%. OTOH, the mod in the linked vid, or better yet, just desoldering the dry wire and insulating it works on all Single, Dual and Triple Recs, so long as they aren't three channels. Am I grokking this right?

 

[Grindr]

I have the three gray wires. I'm pretty sure I don't need to remove them all - just one. If my amp is like the one in the first reply to the OP, I just need to remove the left wire to the mix pot for a first try.

I have an idea for a minimally invasive mod. If the idea is to jumper the emitter to the collector pads, why not just wrap a loop of bare wire tightly around the two transistors (actually, a JFET symbol is used in the schematic) in question, tape the JFETs, and remove the appropriate gray wire going to the pot? If the emitter is shorted to the collector, it wouldn't do any damage to the surrounding components; as the mod in the first reply works. The third JFET shouldn't be removed, as it is part of the mute circuit, and does nothing in this application; but would make reversing it harder. My biggest concern, is will base current through the JFETs burn them out, if the collector and emitter are shorted, but the base is still connected? Of course, the connection wouldn't be great in such a kludge; but might do for studio. The loop of wire might oxidize and make for intermittent contact.

For the curious, the mod in the first reply will make the FX loop always on; and I believe you will need to jumper it.

 

[Grindr]

Epilogue on my attempted mod: I tried removing the wire on the right as seen from the back of the chassis, which was the one on the left on boxcarmonument's original reply - but I could get no sound through the FX loop. I soldered it back and removed the other one. I did get sound through that, and that seemed to be the right one. I put it back together, and tried it. Nada. I couldn't get anything sent into the return to do anything. I have a suitably cheesy Zoom processor, and sent it's output into the return. I couldn't get anything out of it. I have a PCB with (c) 2000 printed on it; so after demoing a Recto at a guitar store, I ordered this one used online, and it was just when the hated 2000-2010 Rectos were released. Problems with this unit:

1. The power switch got wonky; and started making the volume drop to about half as loud as it should, for maybe 10 min. at a time; unpredictably. I fixed that myself.
2. A bias resistor burned out, which I replaced myself.
3. One of the channels doesn't respond to it's remote control switch being thrown. Not fixed.
4. The FX return doesn't work at all. Not fixed.

I'm running NOS EL34's in silicone/bold, and it does sound pretty good; so I'll probably drop back and punt on it, but as it's not pressing, I'll let some money build up. What a service nightmare. OK. Enough ranting.

For the purposes of this thread, my (c) 2000 PCB Dual Recto had the dry signal wire going to the mix knob on the other side; and thus, IMHO, the technique used by boxcarmonument would not have worked on mine; even if the FX return had been working; but IMHO, it would have worked had I simply removed the wire on the left as seen from the back of the chassis. It's not clear if it would have been necessary to remove the two JFETs toward the back of the chassis, since in my case, I couldn't do the one second echo test, what with a broken return. It didn't cause signal through my FX loop to more crappy than they usually do (which is pretty crappy); so I recommend trying just the one wire removal mod first, and only if you are getting enough dry signal to be a problem, proceed with the rest of the mod, but only on the two JFETs toward the back.