What would I need?

[~Abstract~]

To find out if a VH4 and Marshall JVM100H could be run dual mono / stereo thru all channels without polarity/phase issues?

It's my understanding that when a signal goes thru a gain stage the polarity of the signal changes.

That's fine if two amps have the same number of gain stages...but when a set of channels don't match, it can cause reduction in volume and thinning the sound.

Thoughts on how to ensure a planned rig works as well in practice as it does in theory?

 

[~Abstract~]

Had an idea last night when I slept.

If say channel 3 of the VH4 was opposite polarity of the JVM ch3...

Would I be able to reverse polarity of a single channel on the VH4 using the channel inserts?
I could run a jumper across the insert with +/- swapped on one end.

That would only affect that channel right?

 

[Peter Diezel]

That would be a short.

Adam Jones uses his rig with this out of phase sound.

To get the right phase use a LEHLE P-Split 2.
It has a 180 degree phase shift switch and works perfect
also in the channel insert.

Cheers,
Peter

 

[~Abstract~]

Gotcha. Those are nice units. I was contemplating one when I decided on my Radial Bigshot.


Short? From wiring one end of a patch cable backwards?

 

[tripstan]

Had an idea last night when I slept.

If say channel 3 of the VH4 was opposite polarity of the JVM ch3...

Would I be able to reverse polarity of a single channel on the VH4 using the channel inserts?
I could run a jumper across the insert with +/- swapped on one end.

That would only affect that channel right?

Could you do this with the speaker cable? or is that something entirely different?

 

[~Abstract~]

It would then reverse the polarity of the whole subsystem so if I only had a problem with ch3. Check 3 is fixed but 1,2 and 4 would be messed up.

 

[steve_k]

Unless you are running the system on fixed channels, whereby you can reverse polarity with the speaker cable, or with your Radial pedal or as Peter says, the Lehle switchers - you are pretty much limited for altering the phase state of the amp when switching channels. If you are assembling a MIDI controlled two amp set up, the only solution I found was an RJM Y-Not. Have Ron to customize it for you to be able to send a MIDI program change to reverse phase.

 

[~Abstract~]

Unless you are running the system on fixed channels, whereby you can reverse polarity with the speaker cable, or with your Radial pedal or as Peter says, the Lehle switchers - you are pretty much limited for altering the phase state of the amp when switching channels. If you are assembling a MIDI controlled two amp set up, the only solution I found was an RJM Y-Not. Have Ron to customize it for you to be able to send a MIDI program change to reverse phase.

My plan is to run my VH4 and a (yet to be acquired) JVM into their own dedicated cabinets.

I would then use a Peak2005 Midi controller to change channels on both simultaneously.

Guitar to buffered effect (tremolo)...to Radial ABY (Bigshot)...to amp input.

The effects loops would always be on. Stereo Reverb and Delay with both amps using both effects.

I will turn effects on with the effect switch.


I won't be using the channel inserts on the VH4...unless I have a phase issue (I would actually want to correct, Papa mentioned AJ running that tone on purpose) and I assumed I could just reverse phase of that channel with a reversed (tip to sleeve, sleeve to tip) cable...I'm still having trouble understanding how that would induce a short.

Does this sound crazy?
I'm expecting a bit of hum from having both amps running thru several stereo effects...not sure how I'll tackle that...






Thanks so far, and thank you for any and all input!

 

[cheftie]

If you want to run both amps at the same time your 2 main problems could be phase issues and ground loops. Both can be handled well by RJM Y-Not. With it you are able to invert phase via MIDI on Out B, which is an advantage compared to similar products and is very useful if you want to do various channel combinations with both amps. This way you are not going to lose an Insert on the VH4.

 

[i.ak]

I run VH4 and Mako MAK2 simultaneusly. I use RMJ Y-Not for the phase switching. Works perfectly and the best thing is that it is MIDI-pogrammable.

 

[RJF]

What exactly does "out of phase" sound like? I've been running two heads in stereo for a long time now and think it sounds great. I use a GCX audio switcher to split the signal.

 

[~Abstract~]

It's thinner...and kills the balls. Both amps together are thinner with less power than either are alone.

I used to run a 50w Marshall clone (Twister) with a 50w Recto. The cleans were great together...but when I'd switch to Orange on the Recto and cranked the Twister, the sound died. Figured out that the Mesa was adding another gain stage (or 3) to the signal...which didn't play well with the Twister.

I don't remember how I was able to fix it...but it meant that I couldn't run it on the fly. It took a few minutes to correct each time.

One of the many things that lead me to dispose of the Twister.

 

[cheftie]

What exactly does "out of phase" sound like? I've been running two heads in stereo for a long time now and think it sounds great. I use a GCX audio switcher to split the signal.

It does sound thinner and you kind of hear each amp separate and away from the other. THey just don't seem to blend and focus in one point in front of you. The sound somewhat loses punch due to the cancelation. That's the simplest I can describe it.

 

[cheftie]

It's thinner...and kills the balls. Both amps together are thinner with less power than either are alone.

I used to run a 50w Marshall clone (Twister) with a 50w Recto. The cleans were great together...but when I'd switch to Orange on the Recto and cranked the Twister, the sound died. Figured out that the Mesa was adding another gain stage (or 3) to the signal...which didn't play well with the Twister.

I don't remember how I was able to fix it...but it meant that I couldn't run it on the fly. It took a few minutes to correct each time.

One of the many things that lead me to dispose of the Twister.

That's why RJM's Y-Not is great because you can invert the phase via your MIDI footcontroller.

 

[~Abstract~]

I still think I can just run a patch cable across one of the inserts.

 

[Peter Diezel]

You don´t listen to the guys and don´t believe me.

It´s on you.

 

[~Abstract~]

You don´t listen to the guys and don´t believe me.

It´s on you.

It's not just y'all. I don't listen to anyone.

Haha



At least I e got a midi switcher on order now. In just 6 to 8 short weeks I'll be changing channels with my foot, no longer a slave to the little red buttons.


Liebe Papa!

 

[RJF]

Hmm. I notice that if I run ch3 of Herbert with ch2 of my TJ, it sounds not that great. THey kind of sound "separated" from one another. Yet, when I switch to ch2 on Herbert, the sound comes alive and sounds blended. I must assume that it's in phase on that setting.

 

[cheftie]

The way you describe it it seems to be the case.
You can ask a friend to borrow a splitter with a phase invert switch and try it with your amps to make sure it is what we assumed.

 

[~Abstract~]

Or if you have a spare cable laying around you can switch the tip and sleeve of one end.