How the JVM Parallel loop works

Stuff that alters the sound going in or out of the amp, JVM Loops, XLR Out, Line Out, Stereo setup with 2 amps, Midi

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Dark Horse
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Re: How the JVM Parallel loop works

Post by Dark Horse » Mon Feb 27, 2017 2:29 am

First thing to try would be to replace V3 with a new 12AX7 and see if it still happens. If that doesn't fix it, try a swap for V4.

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umersohail
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Re: How the JVM Parallel loop works

Post by umersohail » Mon Feb 27, 2017 6:44 pm

Dark Horse wrote:First thing to try would be to replace V3 with a new 12AX7 and see if it still happens. If that doesn't fix it, try a swap for V4.

DH
noob question...if the corresponding tubes have gone bad, should the fx loop still be operational sometimes and then just die out and then come back on at its own desire? or should it stay bad?

also, does heating got anything to do with this? i noticed that i have put a couple of my stomp boxes on the head, right above the area where the loop I/O is, and that part seems to be emitting a bit of heat?

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Re: How the JVM Parallel loop works

Post by Dark Horse » Tue Feb 28, 2017 1:05 am

Yes, it is possible that a bad tube could result in an intermittent problem.
Also, JVMs emit quite a lot of heat out of the top vent, so that could be normal. I would not block the vent with anything, as the amp needs somewhere for that heat to go. I have a rack bag that sits on top of my amp, and I use 2 in. spacers under it to provide clearance for the vent.

DH
JVM 410H w/Mods: 1µF Plexi Cap, 3H Mojotone Choke, Neg. Feedback Adj. Pot.(500K)

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devilRED
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Re: How the JVM Parallel loop works

Post by devilRED » Sun Apr 23, 2017 5:07 pm

OK thanx to all things i've read in this wonderfull forum i don't have volume loss wen using the FX Loop, im using a Boss DD3 + Boss GE7, the GE7 has the volume raised quite a bit to compensate volume drop of JVM when FX Loop is engaged, also im using the unorthodox tone setting and it works great, no fizz at all and great Rock/Metal tone overall.

Made a quick vid where u can hear and see fx loop on and off

https://www.youtube.com/watch?v=F8LFTn4XdoU&t=35s

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Re: How the JVM Parallel loop works

Post by Lorenzar » Fri Aug 04, 2017 9:50 am

Hey guys !
Like I said on the other thread, I'm officially a new JVM (205H) user !

Before reading this really cool post from Santiago, I've noticed the volume thing with the parallel loop.

I only use in the loop a Danelectro Fish & Chips EQ (that before getting the JVM served me as a second master volume, now it could be a 3rd one or a "kinda OD1 mod" or maybe not usefull anymore, time will tell), a Boss CH-1 Chorus and a Boss DD7 Delay.

Until I put the mix either at 100% WET or 100% Dry, I don't notice a drop in volume. I actually experienced an increase of volume.

Of course, before on my other amps the effect loops was always ON, so I could just set the FX ON everywhere and there will be no problem. Now I want to take advantage of this feature and for some songs put the FX (with chorus) on the clean channel and no FX on the dirt channel, then I won't have to do this button dance on the floor anymore ! ahah!

The increase of volume is probably not much of an issue, as I can balance the Clean and OD channel volumes anyway, and when you engage FX ON the OD channel, a little boost is never a problem (I can also use the level on my EQ to adjust thing, if it turns out I don't use it anymore as a master volume).


What I did so far, to keep the volume the same whether the FX is ON or OFF, is to put the MIX at 90% DRY (which doesn't seem like the most common way, but that's how I felt it). That way, my Delay is subtle, but still present, the way I like it for solos, for the Chorus though, I have to set his own level on the pedal at 75% at least then it can be heard. But it's working for me that way !

Now since I read Santiago post, I'll try to do things differently. If I understand well, the increase of volume I have if I'm around 50% MIX, is due to the direct signal also running through my pedals.

My CH-1 Boss Chorus, actually as 2 output. The A output, you use when in mono, is a mix between Effect and Direct. When you engage both output, A is now Effect only (with B being Direct). So I can try to put a jack which go nowhere into slot B then the signal would be divided and I could use Output A for Effect only, going into my Delay. Then I should only have the Effect sound into the delau as well (anyway, on the DD7 you can do a lot of different settings, they have one in the manual for Loop, which is to plug Send into B input and Return into A output, that way you're on only effect mode as well apparently).

Now if I do this, I guess I could go back to something around the 50% MIX. Now the EQ might be a problem here. I guess it will still give a little bit of direct signal into my loop and if I put the loop after the Chorus with effect output only for exemple, I guess the EQ would only affect the effect signal which would suck.

I don't know if using the EQ upfront is good enough for trying the "OD1 mod" for exemple or using it as another master...but maybe with the JVM I will not need this EQ anymore (I have also an overdrive upfront, set for clean boost, so between this and the Master1/2 thing, if the "kinda OD1 mod" is useless to me, the EQ might be useless).

If I don't suceed in balancing volumes between FX ON and OFF (outside from my method of 90% Dry) and if the EQ becomes useless for EQ and master volume purposes, maybe I should just keep it to adjust the FX ON and OFF volume.


Sorry for the long post, but seems like the loop, is the thing to think a litle about with this amp to make a good use of it ! ahah!

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Re: How the JVM Parallel loop works

Post by Lorenzar » Fri Aug 11, 2017 10:56 am

So I made all those little tests.....actually I just need to put the MIX at 90% WET like many of you guys do I think. My volume is the same with FX ON or OFF, I don't have any phasing issues using the Danelectro Fish and Chips EQ, Boss CH1 Chorus and Boss DD7 Delay, and it's just working perfect that way !

By the way, I tried the "OD1 EQ pedal" mod, I can't care less about it. I wonder if I still need an EQ with the JVM. Maybe I'll keep it to use it as a master with OD Green and Crunch Orange which already use Master 2 in my config. Or maybe I'll set the EQ for more dramatic mid-boost. But the "OD1" mod with the EQ pedal doesn't make a real difference to me (mid boost is really too subtle to me).

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Re: How the JVM Parallel loop works

Post by DavidJ » Thu Aug 02, 2018 2:28 pm

Forgive me if the answer to the question is already in this thread - I got a bit lost.

If I use a stomp box (let's say chorus) and it has no option to separate the wet from the dry signal, then I believe this means I should set the FX loop on my JVM to completely dry and use the controls on the box to determine the wet/dry mix of the final sound?

So if I have got that part right - and let's say my box did have the option of isolating the wet signal (eg through the stereo output) then I should use the wet signal, set the box to 100% wet and then mix the signal on the amp (between 50% and 100% wet?).

I am getting this? Cheers DJ

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Re: How the JVM Parallel loop works

Post by DavidJ » Fri Aug 03, 2018 11:34 am

I think I've answered my own question with some scientific experiments! The fx loop is great now I understand it.

I - Boss Tremolo pedal - only one input and only one output. Set the Fx loop to 100% wet and control the wet/dry mix on the pedal itself. It's a great pedal anyway - but using the FX loop like this sounds slightly better than using the pedal in front of the amp.

2 - Fender analoque delay pedal. This is a revelation - I've never been all that happy with this pedal until now. I put the pedal in the loop and used the stereo output of the pedal (nothing plugged into the main output). I turned the "mix" setting on the pedal to 100%. With the fx loop set to "dry" - that's all you get, just the normal signal. With the fx loop set to "wet" all you get is the echo sound and none of the original note - not too nice.

However - turning mix up between dry and 50% sounded awesome, suddenly my cheapo pedal sounded a lot more expensive! I can get a really good rockabilly, Mystery Train type sound as well as a chunky 80's rock long delay. Much, much better than the quality of sounds available by putting the pedal in front of the amp.

A bit beyond 50% sounds okay too - at this point the echo sounds are louder than the the main signal - not bad if you don't overdo it.

3. Finally for a lark I tried using a boost pedal in the loop (I know this is the "wrong" part of the signal path) on it's own it was so-so, but in conjunction with the tremolo pedal it's a usuable swampy sound.

The more I get to grips with how this amp works, the better I like it!

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Re: How the JVM Parallel loop works

Post by kennetha1a » Tue Nov 06, 2018 12:09 am

Sounds like some good suggestions on this thread to get that fx loop right. I ran into this during first month of having my marshal 215c where the volume would drastically drop for my flanger, trem, and delay pedal. I found that in order to hear the effects coming through i had to raise the wet level up to where the volume would significantly drop anytime i turned on any pedal in that loop.

Fortunately, i already had a morley aby mix box laying around that i hardly use. I can pass a signal through the morely mix and it has a knob for controlling the power of the signal passing through it. I set the level at exactly 50% and put this at the end of my fx loop chain. I keep it turned on fulltime and now have the wet knob on Marshall set at 100%. This fixed EVERYTHING and now my fx loop works like a typical fx loop does (or at least for what im used to). I couldnt be happier!

Final fx chain:
Marshall parrallel/serial send--->Tone city tremolo-->mooer elady flanger-->electro-harmonix canyon delay--->morley mix--->marshall return.

Cheers

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