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

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

Post by dlabrecque » Wed Dec 09, 2009 6:22 pm

Thanks for helping me along. :lol:

But I guess since the FX loop is made to be "full time wet", that does mean the footswitch for the loop changes a bit, right? It would become a kind of mute switch for the amp, wouldn't it? Either the loop is on (full wet, no dry) or it's off (no wet, no dry). Is that right?

Or does the loop footswitch actually switch a separate dedicated direct preamp feed in instead of the loop/mix circuit? That would make sense, since there is a volume loss when engaging the loop via the footswitch. Or would it? :?:
Dave Labrecque
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94Tremoverb
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Re: 3 channel Triple Rectifier Loop Mod.(Parallel to Series)

Post by 94Tremoverb » Wed Dec 09, 2009 6:51 pm

The footswitch simply activates the send/return jacks, rather than bypassing the whole loop circuit - that's why you need to bridge the loop with a patch cable, on the amps with a selectable loop, if you want to run any of the loop functions (Solo etc) with no effects in the loop.

Or, you could copy the circuit from one of the non-selectable-loop amps (eg Single Rectifier) and use a switched jack in the Send, with the switch terminal connected to the return - that does the same thing as the patch cable, but inside the amp.

It depends on how much soldering you want to do :-).

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

Post by newm1ke » Thu Dec 10, 2009 5:13 am

Hey guys I made a post here but I'm now thinking sticking it in this thread is more appropriate.

I made the mod as per picture, though only removing 2 of the resistors. Results are -- soundwise the mod works great! FX sound like they're supposed to again, tone is a +lot+ better. The solo still works and the output still works. The only lost functionality is switching the loop on and off.
However there is a ridiculously huge volume drop as a result of the mod, not sure how much this has been touched on - think someone briefly mentioned a drop, but i wasn't expecting it to be this huge. Is this expected? The output knob has gone from a slight touch will blow your head off to having to crank it to max to make it close to rehearsal level. My plan to resolve this is get a pedal that boosts the volume for the FX loop, does this sound normal? Thanks

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

Post by dlabrecque » Thu Dec 10, 2009 12:31 pm

newm1ke wrote:Hey guys I made a post here but I'm now thinking sticking it in this thread is more appropriate.

I made the mod as per picture, though only removing 2 of the resistors. Results are -- soundwise the mod works great! FX sound like they're supposed to again, tone is a +lot+ better. The solo still works and the output still works. The only lost functionality is switching the loop on and off.
However there is a ridiculously huge volume drop as a result of the mod, not sure how much this has been touched on - think someone briefly mentioned a drop, but i wasn't expecting it to be this huge. Is this expected? The output knob has gone from a slight touch will blow your head off to having to crank it to max to make it close to rehearsal level. My plan to resolve this is get a pedal that boosts the volume for the FX loop, does this sound normal? Thanks
Thanks for the input, newm1ke. Good to hear.

Did your mod leave the mix pot functional at all? If so, could it be that you don't have it cranked all the way clockwise, and so the return level is attenuated?
Dave Labrecque
Becket, Massachusetts

Dual Rectifier Roadster
4x12 Rectifier Slant Front
1x12 Compact Open Back

Boss MS-3 and various pedals
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2006 Fender MIM Stratocaster
2006 Fender MIM Telecaster
2004 Taylor 510CE

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

Post by dlabrecque » Thu Dec 10, 2009 12:36 pm

94Tremoverb wrote:The footswitch simply activates the send/return jacks, rather than bypassing the whole loop circuit - that's why you need to bridge the loop with a patch cable, on the amps with a selectable loop, if you want to run any of the loop functions (Solo etc) with no effects in the loop.

Or, you could copy the circuit from one of the non-selectable-loop amps (eg Single Rectifier) and use a switched jack in the Send, with the switch terminal connected to the return - that does the same thing as the patch cable, but inside the amp.

It depends on how much soldering you want to do :-).
Cool, thanks.

Hey, if this is how it is wired, why does the dry signal drop in volume when the FX loop is engaged, currently, do you know?
Dave Labrecque
Becket, Massachusetts

Dual Rectifier Roadster
4x12 Rectifier Slant Front
1x12 Compact Open Back

Boss MS-3 and various pedals
2002 Gibson SG
2006 Fender MIM Stratocaster
2006 Fender MIM Telecaster
2004 Taylor 510CE

94Tremoverb
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Re: 3 channel Triple Rectifier Loop Mod.(Parallel to Series)

Post by 94Tremoverb » Thu Dec 10, 2009 12:56 pm

Does it still drop in volume if you put just a patch cable in the loop? If not, the volume drop is caused either by the effects units themselves - possibly an issue with either the send or return impedance loading down the signal, or a phase reversal in them. If it does... I don't know! I can't see any reason from the schematic that the volume should drop otherwise.

newm1ke - I saw your other thread. If you can, put everything back exactly as it was and hopefully it will work properly again. Then just disconnect the dry end of the Mix pot. Removing the switching transistors and jumpering the boards like that is totally unnecessary, and I would guess you've just connected something wrong.

There's no logic to removing the transistors in the interests of "purity", unless you are using an all-tube effects chain, and even then it really wouldn't matter. There are at least two Mesa amps that deliberately use transistors in the signal path (carefully without telling anyone they're there) to *improve* the tone. If you really want purity, just bypass the loop altogether with the rotary switch.

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

Post by dlabrecque » Thu Dec 10, 2009 1:49 pm

Hey, 94 -- did you see the mod schematic earlier in this thread (not the photos, the schematic, which is different, I think)? Why do you think they're messing with resisters and doing all the extra jumpering stuff? You're basically saying cut a single wire, right?

That's the same mod schematic that a tech at Mesa sent me.
Dave Labrecque
Becket, Massachusetts

Dual Rectifier Roadster
4x12 Rectifier Slant Front
1x12 Compact Open Back

Boss MS-3 and various pedals
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2006 Fender MIM Stratocaster
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94Tremoverb
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Re: 3 channel Triple Rectifier Loop Mod.(Parallel to Series)

Post by 94Tremoverb » Thu Dec 10, 2009 2:30 pm

Yes, I saw the schematic - that's what I'm basing saying that it should make no difference to the volume on. I really don't know why they want you to do all that stuff. To be honest I haven't looked very closely at either that or the instructions earlier on to see exactly what they're trying to do, since I *know* that the only thing you need to do is remove one wire. It's worked perfectly on every one of the several Mesa amps (I forget exactly how many, more than five and less than ten but all different models) I've done this to.

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

Post by newm1ke » Sun Dec 13, 2009 5:46 am

Hey guys thanks for replies, just thought I'd update you on he issue I had coz I think I've resolved it. I got the MXR 10 Band EQ ped you guys are all raving about, stuck it at end of loop (well, before delay) and cranked the gain/volume levels on it and it now works great. It cranks the volume comfortably again, nowhere near as much as before the mod but I prefer it like this as the output is much more management rather than millimetres. I had a good rehearsal/gig volume at 2 o'clock on the output, and can engage solo if needed more for watever reason. Very happy with this mod.

The only remaining issue is channel switching. There's still very loud thuds when switching between channels, louder as the volume goes up. This is maybe something for another thread as I've tried the FAQ stuff of switching through channels in standby but still doing it throughout practise.

Other than that, very happy with the results :)

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

Post by Mitch Connor » Sat Jan 02, 2010 6:54 pm

94Tremoverb wrote:Why would you need to go to all this trouble? The *only* cause of the issue with phase and latency is the link from the Send level pot to the Mix pot allowing a small amount of dry signal through, so if you simply break this connection it's fixed. That leaves all the other functions of the loop working as normal.

(I don't have a Triple Rec by the way, I got directed to this thread from elsewhere, but I've done this mod to several Mesas and I can guarantee that it works perfectly.)
Just wanted to let everyone know that this worked for me. I recently bought a Boss Re-20 space echo and a volume pedal and wanted to run them along with a chorus pedal in my FX loop. I have a mid 90's 2-channel Dual Rectifier solo head and was quite frustrated by the residual (~10%) dry signal remaining in the chain when the mix knob was at 100% wet.

So, I found this forum, found this post, opened up my head, de-soldered the green wire running from the send pot to the mix pot, and wrapped the end with some electrical tape. It was extremely simple, took maybe 10 minutes. Fired my amp back up, the loop rotary dial still works (bypass, on red & orange, red only, orange only, foot switchable), and now no dry signal is passing through my FX loop when the mix is at 100% wet. Works just like I wanted it to. I couldn't be happier. Thank You 94Tremoverb :mrgreen:

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

Post by krylon » Sun Jan 03, 2010 2:52 am

my TR never had this wire directly from the send to mix pot. the dry end of the mix pot had a wire going to the pcb like in the pic on the first page. i desoldered it and still had bleed. so i reversed it. i'm not about to jump thru all those rings on that mod in the OP. paralell loop it is for now.

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

Post by dlabrecque » Sun Jan 03, 2010 11:53 am

Mitch Connor wrote:
94Tremoverb wrote:Why would you need to go to all this trouble? The *only* cause of the issue with phase and latency is the link from the Send level pot to the Mix pot allowing a small amount of dry signal through, so if you simply break this connection it's fixed. That leaves all the other functions of the loop working as normal.

(I don't have a Triple Rec by the way, I got directed to this thread from elsewhere, but I've done this mod to several Mesas and I can guarantee that it works perfectly.)
Just wanted to let everyone know that this worked for me. I recently bought a Boss Re-20 space echo and a volume pedal and wanted to run them along with a chorus pedal in my FX loop. I have a mid 90's 2-channel Dual Rectifier solo head and was quite frustrated by the residual (~10%) dry signal remaining in the chain when the mix knob was at 100% wet.

So, I found this forum, found this post, opened up my head, de-soldered the green wire running from the send pot to the mix pot, and wrapped the end with some electrical tape. It was extremely simple, took maybe 10 minutes. Fired my amp back up, the loop rotary dial still works (bypass, on red & orange, red only, orange only, foot switchable), and now no dry signal is passing through my FX loop when the mix is at 100% wet. Works just like I wanted it to. I couldn't be happier. Thank You 94Tremoverb :mrgreen:
Really appreciate the info, Mitch. So, are you saying that there has been absolutely no change in the way everything works, except for the 10% residual dry going away when the mix pot is set to 100%? Solo and master pots still work? All footswitches still work?

Or is it that the mix pot doesn't do any mixing anymore? Is it 100% wet all the time now, regardless of where the mix pot is set?
Dave Labrecque
Becket, Massachusetts

Dual Rectifier Roadster
4x12 Rectifier Slant Front
1x12 Compact Open Back

Boss MS-3 and various pedals
2002 Gibson SG
2006 Fender MIM Stratocaster
2006 Fender MIM Telecaster
2004 Taylor 510CE

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

Post by Mitch Connor » Sun Jan 03, 2010 2:07 pm

krylon wrote:my TR never had this wire directly from the send to mix pot. the dry end of the mix pot had a wire going to the pcb like in the pic on the first page. i desoldered it and still had bleed. so i reversed it. i'm not about to jump thru all those rings on that mod in the OP. paralell loop it is for now.
Yeah, my 2-channel dual rectifier didn't have this sort of setup.
dlabrecque wrote: Really appreciate the info, Mitch. So, are you saying that there has been absolutely no change in the way everything works, except for the 10% residual dry going away when the mix pot is set to 100%? Solo and master pots still work? All footswitches still work?

Or is it that the mix pot doesn't do any mixing anymore? Is it 100% wet all the time now, regardless of where the mix pot is set?
Well, my Dual Rec. doesn't have a solo switch or any of that. It just has a single button footswitch to change between the orange and red channels. There is the single "Loop Active Master" that controls both channels' overall volume when the Loop is engaged, and yes that still works normally. The FX mix pot/knob doesn't blend the dry and wet signal anymore. I think someone (probably 94Tremoverb) mentioned that it now acts more like an FX return level. If I set it to 0% there is still a wet signal coming through, but the original parallel dry signal is completely gone. I like it this way, at 100% it appears to work just like a serial FX loop.

If I get a chance I'll pull the amp apart and attach a photo to show you what I did. Again, it was extremely simple and easily reversible. However, your situation may not be exactly like mine.

EDIT: Here are the photos. And if anyone was wondering why it looks like I'm missing tubes, I run my amp with the two middle power tubes removed. Also, the FX rotary knob is attached incorrectly which is why it's pointing to 'nothing'. It's actually set to "LOOP ON ORG & RED".
Image
Image
Image

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

Post by dlabrecque » Sun Jan 03, 2010 5:19 pm

Thanks, Mitch. Maybe I'll give it a whirl one of these days...

I have the three-channel dual rec, so I'm not sure how it looks inside.
Dave Labrecque
Becket, Massachusetts

Dual Rectifier Roadster
4x12 Rectifier Slant Front
1x12 Compact Open Back

Boss MS-3 and various pedals
2002 Gibson SG
2006 Fender MIM Stratocaster
2006 Fender MIM Telecaster
2004 Taylor 510CE

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

Post by krylon » Sun Jan 03, 2010 6:15 pm

in my 3ch TR (Rev. E i think). this is what it looks like, the wire circled in yellow is the wire that goes to the dry end of the mix knob. this is the one i desoldered then reversed.
Image

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