effects loop problem on a modded jmp

danielguitar79 · 06-26-2008, 08:56 AM

Hi i have a 77 jmp 100 watts modded by jim caswell (#39 modd), the modd includes 2 channel, the original and the #39 channel (more drive kind of slash tone) an effects loop and a clean channel. all of this mods are footswitchable, includin the effects loop, i notice today that when i switch on the effects loop (even when i dont have anythin in it) the sound changes the volume drops and it gets a little more trebly, or kind of when you put the presence knob on full, maybe its not that big of a difference but my ears can notice it, i normally use a eq pedal, boostin the mids and highs (not too much) and of course the volume for a solo boost so its not really that big of a deal but i would like to fix this if its not too complicated.
Also when switch to clean it makes a popin sound, again when playin live its hard to hear it but its still there and i would like to fix it just to say i have the perfect amp

thank u for the help, u guys r the best group ever!!

Brett Blackmore · 07-03-2008, 08:34 AM

Hi,

I modded my fx-loop and I had a strange phenomen at the beginning too. My mod is called an interupt fx-mod. With no fx-in the loop the signal flows uninterupted from the signal inverter, across the contacts of the 2 fx-sockets and returns to the center tip of the treble knob. If you place a cable into the fx then this signal flow is interupted - it flows into the cables of the fx instead. If one of the jacks thinks there is still a cable inside (like the contacts were not closed properly when you last removed a cable) then it will route the signal into an absent fx unit - into fresh air - this happened to me. My jacks were brand new and maybe the material was stiff etc.

Also often the contacts in an fx-loop get slightly corroded as they are not used so much. Another reason for them to stick sligtly open. Try getting some contact cleaner and plug a jackplug in and out untill they are clean again.

Cheers Brett

danielguitar79 · 07-04-2008, 12:10 AM

thanks brett im gonna go and try that out.
d

06-26-2008, 08:56 AM	#1 (permalink)
danielguitar79 Member Join Date: Jun 2008 Posts: 36	effects loop problem on a modded jmp Hi i have a 77 jmp 100 watts modded by jim caswell (#39 modd), the modd includes 2 channel, the original and the #39 channel (more drive kind of slash tone) an effects loop and a clean channel. all of this mods are footswitchable, includin the effects loop, i notice today that when i switch on the effects loop (even when i dont have anythin in it) the sound changes the volume drops and it gets a little more trebly, or kind of when you put the presence knob on full, maybe its not that big of a difference but my ears can notice it, i normally use a eq pedal, boostin the mids and highs (not too much) and of course the volume for a solo boost so its not really that big of a deal but i would like to fix this if its not too complicated. Also when switch to clean it makes a popin sound, again when playin live its hard to hear it but its still there and i would like to fix it just to say i have the perfect amp thank u for the help, u guys r the best group ever!!

07-03-2008, 08:34 AM	#2 (permalink)
Brett Blackmore Senior Member Join Date: Apr 2008 Location: Bingen, Germany Posts: 461	Re: effects loop problem on a modded jmp Hi, I modded my fx-loop and I had a strange phenomen at the beginning too. My mod is called an interupt fx-mod. With no fx-in the loop the signal flows uninterupted from the signal inverter, across the contacts of the 2 fx-sockets and returns to the center tip of the treble knob. If you place a cable into the fx then this signal flow is interupted - it flows into the cables of the fx instead. If one of the jacks thinks there is still a cable inside (like the contacts were not closed properly when you last removed a cable) then it will route the signal into an absent fx unit - into fresh air - this happened to me. My jacks were brand new and maybe the material was stiff etc. Also often the contacts in an fx-loop get slightly corroded as they are not used so much. Another reason for them to stick sligtly open. Try getting some contact cleaner and plug a jackplug in and out untill they are clean again. Cheers Brett

07-04-2008, 12:10 AM	#3 (permalink)
danielguitar79 Member Join Date: Jun 2008 Posts: 36	Re: effects loop problem on a modded jmp thanks brett im gonna go and try that out. d __________________

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