EFFECTS LOOP NIGHTMARE!!

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johnny6l6

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Hello one and all. please bear with me as i new to mesa's and the whole forum thing.
here's my problem:
i have a 3ch dual rec head. with the loop dial set to bypass i have the use of the three channels as per normal.
when the dial is set to anything else i get no sound at all. i've tried adjusting the effects mix, the volume on the front, the solo volume and there is nothing. but like i say in bypass the 3 channels do as they should.
the lights on the pedal board light up when pressed for the loop and solo but there is nothing.
anyone ever had this problem or know what it is?
john. :cry:
 
just looked at the online manual and one of the valves is for the fx loop. if this is faulty will it stop the loop from working?
 
Welcome to The Board.

johnny6l6 said:
just looked at the online manual and one of the valves is for the fx loop. if this is faulty will it stop the loop from working?
Yes. V4 is the FX Loop Driver/Return Buffer.

Also, if the amp is used, the loop may have been modified to series. Try running a patch cable from Send to Return and see if it works.

Dom
 
If the problem is indeed the tube (valve) do not use any of the current production New Sensor Corp. tubes in this position. V4 ( & V3 ) are Cathode Follower positions, and New Sensor's tubes have been proven to fail in these positions. New Sensor brands include Sovtek, Electro-Harmonix, & the Tung-Sol reissue. The old Mesa "Russian-1" is a Sovtek, and Mesa "Russian-2" is an Electro-Harmonix and should also be avoided. The current Mesa 12AX7 "Russian" is a JJ and works fine in these positions, as well as any Chinese (Shuguang/Penta, GT 12AX7-C) or NOS.

Dom
 
Here's another thing to check: There's a multi-pin plug going into the back of the FX select pot. Make sure that it is seated properly.

I had a similar situation with my 3 channel Dual Rec, and that was the culprit.
 
thanks guys.
i know the valve in there is jj valve. i had a look to see if there was anything wrong with it (a bit pointless as i don't know the characteristics of a knackered valve).
if it has been rewired to run in series so it needs a patch lead, where do i plug my effects into? i know from experience that things like delay and reverbs sound rubbish going direct into the input.
mikey383, is the back of the pot easy to get to? i just imagine there to be a LOT of electronics inside.
all this help really is appreciated, thankyou. :)
 
crikey this is a complicated amp........
everytime i read the online i think ''right, ok, didnt see that before''
it almost seems the manual contradicts itself, or forgets to mention a small piece of info.
on page 9 it says that the front output control next to the solo control , controls the overall volume of the amp..........it fails to mention that you have to have the loop bypass off in order for this to work. that bit of info is on page 11. grrrr.
still without a working effects loop its just two shiny knobs on the front.
if the multi pin plug is easy enough i'll have a try at that today.
 
First completely unplug all of your effects and only plug in your guitar, amp and cab. The reason you are doing this is to see if the problem is in the amp or some place else in the chain.

The way to test the tube is put a tube in there you know works. If you do not have a spare .... just switch around the ones that are already in the amp. Just a matter of elimination to figure out what one is bad.
 
morning people. well i tried the patch lead across the send and return but no different.
changed the v4 for v3 and success . we have sound from the effects.
only on the clean channel which im guessing is because the dead valve is not allowing the other two channels to allow signal to pass through. the v3 was the boost stage for ch2+3.
well i should get it serviced now as i dont know when it was last done and prevention is better than the cure.
thanks for all your help guys. :D
 
so also not sure about jj valves or any for that matter. my other amp has always had stock issue valves fitted (marshall 2555sl).
so my valve knowledge is minimal. i don't know what is good, what is bad or even the difference in tone available.
i understand that valves is a massive topic. i'll buy stock mesa 6l6's as back ups along with standard issue rectifier valves.
preamp-wise are these good :
http://www.watfordvalves.com/product_detail.asp?id=1794

having spares is always advisable as we know but this is my first mesa and really want to look after it so advice from members on here is better than any store can give me.
:D
 
johnny6l6 said:
morning people. well i tried the patch lead across the send and return but no different.
changed the v4 for v3 and success . we have sound from the effects.
only on the clean channel which im guessing is because the dead valve is not allowing the other two channels to allow signal to pass through. the v3 was the boost stage for ch2+3.
well i should get it serviced now as i dont know when it was last done and prevention is better than the cure.
thanks for all your help guys. :D

Glad you found the culprit! You are correct that you only have a clean channel because the "dead" tube from V4 is now in V3.

johnny6l6 said:
so also not sure about jj valves or any for that matter. my other amp has always had stock issue valves fitted (marshall 2555sl).
so my valve knowledge is minimal. i don't know what is good, what is bad or even the difference in tone available.
i understand that valves is a massive topic. i'll buy stock mesa 6l6's as back ups along with standard issue rectifier valves.
preamp-wise are these good :
http://www.watfordvalves.com/product_detail.asp?id=1794

having spares is always advisable as we know but this is my first mesa and really want to look after it so advice from members on here is better than any store can give me.
:D

I do not know who the supplier of these tubes are. The pictures of the standard ECC83 appear to be JJ's. If they are, they will be fine for the cathode follower positions I mentioned earlier. You should inquire Watford about that subject if indeed you do purchase tubes from them.

Being that this is your first Mesa Rectifier, I would re-tube with all Mesa tubes so you can create a baseline for the amp. Mesa tubes are selected to be strong reliable tubes. Once you get to know the amp, then down the road you can experiment with different brands of tubes.

Remember, the Mesa Rectifier's EQ is nothing like the Marshall you are used to. Do not try to dial it in like a Marshall, you will be extremely dissapointed. Start with the Bass, Mid & Treble at 12:00 (midway), and keep the gain under 2:00 in the Lead channels. Use your ears, not your eyes!

Also, print out the online manual and read it. It is not a step by step reference guide. It is an in-depth explaination of your amplifier. It will explain how the EQ and Gain controls interact, as well as how to properly utilize all the functions of your new amplifier.

Good luck, and remember, we are here to help if you need it!

Dom
 
top tips thankyou. is there anything that would have caused the valve to fail? i recall the guy saying when i bought it that they werent that old. not brand now but nor old. is it possible being that it was responsible for the loop it was something in the effects pedals/power supplies themselves? or it just died plain and simple.
 
ok, well i'm just about to take it to have a service.
when i buy the preamp valves should i stick to all 12ax7's for all 5 or each ones type specific? :?
 
If the person that you got the amp from said the tubes are fresh and it sounds good I would just replace the one tube that is bad. I also recommend picking up a pair of power tubes as spares. They are usually replaced in pairs or all replaced. Picking up a extra preamp tube is a good idea also.

If you are going to replace all the tubes I also recommend getting the tubes from Mesa..... as mentioned above.

Tubes are a lot like light bulbs ... you never know how long they will live and it is easy to get a bad one that is new. Like tires and brakes they are just going to need to be replaced some times....
 

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