Merlin's Practical Serial Effects Loop layout

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telentubes
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Re: Merlin's Practical Serial Effects Loop layout

Post by telentubes »

I was going to put a .01uf right after pin 6, then start the loop after that. The return of the loop would head to the Master Volume right side lug. The left lug would go to ground. The wiper will go to the PI, via a 1k2 resistor then a .02uf cap. Thanks for that reminder. Could be easy to forget with it missing on the schematic.
studiodunn
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Re: Merlin's Practical Serial Effects Loop layout

Post by studiodunn »

Do pins 4,5&9 all need tied to ground?
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martin manning
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Re: Merlin's Practical Serial Effects Loop layout

Post by martin manning »

4, 5, and 9 on the 12AX7? They have to be connected into the filament string.
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Re: Merlin's Practical Serial Effects Loop layout

Post by telentubes »

I just finished this up yesterday, so the timing of your question is perfect. It's near impossible to see all that is going on here, and I will try to get some better shots to post, but this gives a layout option. The heater wires are attached at pins 4/5, and 9, like the other preamp 12AX7s.
Merlin's effects loop.jpg
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M Fowler
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Re: Merlin's Practical Serial Effects Loop layout

Post by M Fowler »

Beautiful workmanship there.
studiodunn
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Re: Merlin's Practical Serial Effects Loop layout

Post by studiodunn »

Thank you Martin, I typed before thinking.

Tele - That is stellar looking work sir. Thank you for making me embarrassed to post my gut shot ;)

Loop works great! I have some strangeness in how the MV and Treble are working in conjunction, But I think I have and idea of what I've wired up wrong.
I'm using a Stereo jack since the pedal I built to use is set up the same way...one less cable to deal with.

I'm going to try a few things and will report back, but again, thank you all.
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studiodunn
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Re: Merlin's Practical Serial Effects Loop layout

Post by studiodunn »

Got this all sorted and working great. I have zero tonal change and unity gain.

The only issue being a scratchy MV now. It almost drops the signal momentarily and then recovers once I stop turning the pot.
The loop is placed between the Tone stack and the MV.
Any suggestions?
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JazzGuitarGimp
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Re: Merlin's Practical Serial Effects Loop layout

Post by JazzGuitarGimp »

Do you have an AC coupling cap between the loop output and the MV pot?
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studiodunn
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Re: Merlin's Practical Serial Effects Loop layout

Post by studiodunn »

JazzGuitarGimp wrote: Mon Nov 20, 2017 7:11 pm Do you have an AC coupling cap between the loop output and the MV pot?
Doh! Thank you JGG.
gsb
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Re: Merlin's Practical Serial Effects Loop layout

Post by gsb »

Hi !
I,m building jtm45 with PPIMV. I have Merlins book but question is -to do or not in that build .Player has some TC delay etc .
Thanks for help
gsb
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dorrisant
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Re: Merlin's Practical Serial Effects Loop layout

Post by dorrisant »

Modulation effects are best in the loop with that model...
"Education is what you're left with after you have forgotten what you have learned" - Enzo
gsb
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Re: Merlin's Practical Serial Effects Loop layout

Post by gsb »

Hi !
For JTM45 i think parallel will be better or not ?
Thanks GSB
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dorrisant
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Re: Merlin's Practical Serial Effects Loop layout

Post by dorrisant »

gsb wrote: Fri Feb 23, 2018 8:48 am Hi !
For JTM45 i think parallel will be better or not ?
Thanks GSB
Maybe, maybe not... Depends on personal taste. You could have it serial or parallel by installing a switch. Most people would say serial though.
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wattsup
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Re: Merlin's Practical Serial Effects Loop layout

Post by wattsup »

I want to try this. If I were going to put a control pot on the return, would I put a 1M pot in place of the 1M resistor, or put a coupling cap after the 100K resistor and then a 1M or something like that value going to the phase inverter?
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xtian
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Re: Merlin's Practical Serial Effects Loop layout

Post by xtian »

wattsup wrote: Thu Oct 25, 2018 4:06 pm I want to try this. If I were going to put a control pot on the return, would I put a 1M pot in place of the 1M resistor, or put a coupling cap after the 100K resistor and then a 1M or something like that value going to the phase inverter?
Just replace 1M with pot. To me, this is unnecessary, because the Send level control covers that base.
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