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[rnolan]

Hey RG, I suspect you are correct, with the Marshall my feedback was more volume related than gain, well a bit of both but the '73 Marshall input stage is not as high gain as some later amps and gadgets.  I do need to use the MP-2 built in gate for its really high gain voices.  The MP-2 gate gives you the option of fader release rather than hard gate which I prefer.  Other gates I've used in live PA rigs (mostly for drums to improve separation and rings) are a bit more sophisticated and give you control of attack and release times etc.  You can get rack versions of these with 4 (or more) gates, maybe an option to consider as these days allot of people are using digital consoles which have gates (and other goodies) built into to each channel (saves allot on patching as the gates are usually connected to channel insets) so there would be some on the 2nd hand market.

[rabidgerry]

I spent a lot of time with noise gates and I was happy when I found the decimator. For me the dual gate setup is the best way, I did a lot of experimenting with different brands and the dual gate was always the best solution.

Don't think that the feedback is coming from the guitar itself but it can come from either the strings or the pickups.

I just can't help feeling I shouldn't need two gates.  I almost certainly have a ground loop as well which I think throws some horrible resonating frequencies into the mix and adds another feedback trigger.

But I'm going to employ the two gates technique and see how it goes.

Hey RG, I suspect you are correct, with the Marshall my feedback was more volume related than gain, well a bit of both but the '73 Marshall input stage is not as high gain as some later amps and gadgets.  I do need to use the MP-2 built in gate for its really high gain voices.  The MP-2 gate gives you the option of fader release rather than hard gate which I prefer.  Other gates I've used in live PA rigs (mostly for drums to improve separation and rings) are a bit more sophisticated and give you control of attack and release times etc.  You can get rack versions of these with 4 (or more) gates, maybe an option to consider as these days allot of people are using digital consoles which have gates (and other goodies) built into to each channel (saves allot on patching as the gates are usually connected to channel insets) so there would be some on the 2nd hand market.

  Oh I'd love the luxury of adding a more sophisticated gate and another unit to my rack but unfortunately for me, the smaller the rig I have the easier it is.  I'd love to be wheeling a "fridge" sized rack around with me with all my fav units included and wired up in a million different ways.  Adding pedal gates into the chain was so they can get stuck in the back of my rack case.  The GX700 has a built in noise gate but I think I'd get a purer signal without using it.  I could also be paranoid 

[rnolan]

Hey RG, if your rack has rear mounting rails, you could include a 1 RU multi gate rack unit from behind (typically they are not very deep units), once they are set you wouldn't need to touch them (from the front).  Can you adjust where the GX700 gate sits in the signal chain? seems to me it would be worth a try but depends where it sits in the signal flow.

[rabidgerry]

I actually was using Boss NS-50 noise gates for a long time and I actually can't remember why I stopped that.  I think I was having crazy feedback issues again but to do with the inputs on the NS-50 or something like that.  So I just switched and thought it sounded a bit better.

Yes the loop is moveable on the GX-700.

[rabidgerry]

Tried the two gate approach and it nothing for me unfortunately.  So I am inclined to think it isn't guitar resonance triggering the noise.

One thing I noticed when the Silencer gate doesn't close in time properly is a weird hum sneaks through.  I kinda wonder is the ground loop making crazy noise and triggering the gate to stay open?  I never ever did got rid of my ground loop issues.  Well I did with my old setup way back, but since I went all rack I never got rid and just lived with it.  Perhaps I need to fix this first.  Also power supplies in the back of my rack cause may be another contributing factor to excessive noise or hum that is messing up the gate performing properly.

[rnolan]

As you say the hum wont be helping. Have you tried the 3 different ground switch positions on the back of the rockmaster ?  may help       
 
I thought of another patch for you to try: 
Guit > Boss input > Boss send > RM input > RM send > Silencer input > Silencer send > RM return > RM output > Silencer return > Silencer output > Boss return 

Use the RM Common EFX Loop as it's used for all RM modes (but you could also try other EFX loops probably the higher gain ones?).

[rabidgerry]

Hi Richard,

the Rockmaster UK version has no ground switch unfortunately so can't utilize it.

So I traced one source of hum, basically the GX700 has a power supply in an inline format.  I had it stuffed in the back of the amp rack case.  So I realised that where it was situated was right next to the Peavey 50/50 transformers.  So I dunno where I will locate this permanently, but I do know for the time being moving to out of the rack and lying somewhere out the back of the rig helped reduce the hum I was getting quite a bit.  However some hum still remains.  I'm convinced this is from the peavey rockmaster.

Today's practice was unbearable.  So much feedback and very few positions for me to stand in where I could manage it.  So another discovery occurred whilst trying to look for hum offenders.  Basically the drums are setting the feedback off also.  The drummer did one kick on the bass drum and whilst I had the gate off, and volume up the feedback occurred.  So what the hell am I supposed to do with that?  I mean where my amp and cabs are set are like a stage currently.  So cab stack either side of the drummer.  What am I supposed to do, ask him to stop playing drums?  I have to get rid of this issue as I cannot play without feedback interference distracting me from rocking out.

I also swapped amp and it seemed like this helped, but in reality it was still the same.

So hum and feedback need to be eliminated and I do not know how.

I also tried the setup you suggested Richard with the send from the Boss GX700 feeding the silencer side chain.  Again seemed to help for about 3 seconds.  So in reality pretty much the same as feeding the silencer the pure guitar signal.  Absolutely fed up.

[rnolan]

Hey RG, complete empathy for your exasperation  .  IIRC you have been running your rig the way you have it patched (minus the gates) for quite a while and never had all these problems ??  My inclination has always been make the patch rockmaster centric not GX700 as in use the GX700 for effects, so either put it in the rockmaster main loop (as it has 4 loop options) (but loose stereo) or use a small mixer and run the GX700 off a mixer Fx send so you can bring it back in stereo into 2 channels, mixer stereo out to power amp.  This is a much better setup for gain structure. 

For the kick drum to be setting your rig off (or any other really loud noise) implies tubes (and or PUs) being microphonic.  There's no such thing as no microphonics in either tubes or PUs, just some less than others.  At a certain volume (usually very loud) anything will feed back.  Hums are a headache as lots of things can cause them, like having the GX700 PSU close to transformers.  But also for some they find the various devices earthing to each other via the rack rails causes issues.  I've never experienced this issue thankfully.  Another exacerbator of hum (and noise) is old electrolytic caps which is the main thrust of the MP-1/2 noise mods. 

Solutions include isolate in the rack (unit and mounting screws insulated from the rails) 
New low microphonic tubes  (generally short plate tubes are less susceptible)
Recap preamp and amp 
Keep input and power leads well apart, if they have to cross, cross at right angle to lessen any induction 
Keep everything away from transformers, particularly power amp transformers 
Wax pot PUs (which you've done) 
Ensure all good quality leads, the shield in leads can also break down over time but mostly for guitar leads as they are subject to physical ware 
Keep rack away from vibrations, e.g. not on top of cabs 

But you know most (if not all) of this. 

When you play really high gain though, it's always on the edge, hence MJMP utilising 2 gates to control it.  If I use the really high gain settings in my MP-2 I have to use its built in gate.  At such high gain is also where tube microphonics (and hum/noise) are more pronounced. 

If hum is from the rockmaster (and I agree that's likely) then it needs a retube and a recap.  It's an old unit, the electrolytic caps will have hardened (as they have in MP-1/2 etc.)  The 50/50 is also old and will have the same issue.  Maybe use your Koch instead? It's much newer and solid state. 

Have you considered building a rig around your MP-1?

[rabidgerry]

To be fair I have always had feedback issues.  But there has been two years of very little band action as well and I hadn't long switched to all rack set up really before it all came to a stand still.  It's just a lot worse now.  I'm in a different practice room also.  The last one I was in was for over 10 years and my rig was away from drums and facing them drummer.  I've always suspected other vibrations from other sources (bass gear, drums) to be a contributing factor and have never quite been able to prove it.  And now I know it has been which would explain why in some venues it was worse than others depending on where I was on stage.

As for solutions, I do know most of those things.  Time to resolve them all though is in very short supply.  I guess this is what I get for buying better, but much older equipment.

Yeah I know the rockmaster probably needs those power caps changed.  Seem very accessible.  I just need to get replacements and time t swap them out.

The GX700 I hate to admit, I believe might be microphonic also.  I've had suspicions about the inputs for a while, but I really would not know how to fix this.  I can't swap over to the Digitech GSP1101 just yet.  It would take a while to get used to the unit and replicate similar patches I have on the GX700 on this unit and then work out all the mid stuff to for the FCB1010.

Ok another psu I use for powering the Silencer pedal was in the back of my rack too.  This could well be a feedback contributor also from vibrations etc.

Yes I would consider building my rig around one of my MP1's but I feel It wont be a matter of just swapping it out with the rockmaster.  Plus I need a boost in front of my MP1 (not the 3TM) and I just know that the addition of the boost is asking for more trouble.

[MarshallJMP]

Do you use a boost in the boss to boost the peavy?

[rabidgerry]

No I don't use a boost with the peavey.  However for different flavours I have wanted to boost using a variety of other pedals, mainly an EQ for a specific kind of tone but needless to say I can't enjoy anything like kind of thing unless I am at my home setup where I listen to it all with headphones.

The Peavey has a pull switch in the gain knob for both crunch and Ultra channels, this acts as a boost kinda built in for the Peavey.  I play on about number 6 on the Peavey with the push/pull pot pulled out to engage the boost.

Really not sure the Peavey preamp tubes are microphonic, they aren't that old.  There is the tap test right?  How do I do this?

[rabidgerry]

Here is a video.  Beware of the feedback though so as not to hurt your ears.  So yo can hear the hum, which was worse remember until I moved the boss power supply away from the back of the Peavey Classic 50/50.  So this is the hum that remained.  And my amp is turned up very loud hear to demonstrate, also the gate is off.

[rnolan]

Hey RG, well that feedback sounded normal for when you're guitar is up close.  Do you use a power conditioner?  Has this got worse since you moved rehearsal space?  There is always some hum & noise when you crank up, particularly with older gear (often caps  ) but noisy power can be part of the issue?  The only way to "really" fix that is to build/buy a proper balanced power setup which phase cancels all the noise from everyone else on your bit of the power grid. Although allegedly power conditioners do help. 

Your silencer PSU shouldn't be microphonic but, like the GX700 PSU can be affected by inductance and RF from the other power transformers. 

The tap test is to lightly tap each tube while powered up and gauge how loud you hear it.  You could use the tip of a jack plug (gently).  Generally with the gain up at your normal level, you will hear the tap, but if a tube is very microphonic it will be noticeably louder.

[rabidgerry]

That hum doesn't sound normal to me, it's way too loud.  I'm sure this is from the rockmaster.  I remember when I first bought that preamp someone had disconnected the ground inside the plug.  I obviously reconnected it.  But when I used the rockmaster in the loop of my GT5 before going full rack I remember having this hum and when I tested it I removed the ground of the rockmaster plug and turned it all on and the hum had gone.  So that is when I employed the Art Clean Box II which is basically transformers in box to remove ground loops from setups etc.  It worked for me, albeit at the cost of a few db in signal.  But then I moved to rack.  So there are many more possibilities now for these loops, casing, rack rails, etc so I'm going to need to get the multimixer out and go through my rack.  But I think the hum is only one contributing factor to to this overall feedback issue as a mentioned in my post before the video.

[rabidgerry]

So I guess it's going to be a process of elimination.

I will start off with what I think is the easiest to re-cap (less caps).  I'm going to re-cap the Rockmaster preamp.  Are their premium caps you can buy that do not degrade?  I could replace the three big power caps and see if this has any affect or not.

The GX700 on the other hand has a lot of caps.  So I'm going to attempt this last.