#1
So I just got a new amp today, an EVH 5153 50 watt head.

But I've run into a showstopper that's preventing me from enjoying the amp; The effects loop is ridiculously noisy.

I'm running an MXR 10 band EQ, and MXR Analog Chorus a TC HOF, a CC and a Ditto in the loop.

Whenever I run the effects loop and run any of my pedals, the amount of noise I get is astronomical. Not only is there a lot of buzzing, but there's a ton of upper harmonics in the noise. Increasing the volume of the amp does not increase the volume of the noise.

I performed some processes of elimination. With only the EQ pedal in the loop of the 5153, and when I am also running a different power supply to what I normally use, (in which case I am using the supply that the pedal originally came with) I get a ton less noise.

However, when I use my pedalboard's power supply with only the EQ pedal in the loop, the noise returns again. The noise only occurs when the pedal is switched on. This is interesting to me because the MXR 10-band EQ is still powered when the EQ is turned off; the volume and gain sliders still function.

This leads to me believing that the issue is with my pedalboard's power supply, rather than the amp.

However, what muddies the water on that theory is that on my heavily modded 6505+ 112, I am not experiencing any adverse amounts of noise whatsoever. Even when I'm using the pedalboard power supply I normally use. But on the EVH, I am getting a ton of that noise. Why is it that I'm getting so much noise with the same power supply with the EVH than I am with the Peavey?

Because of this, the solution to the problem seems about as clear as mud.

Does anyone have any further suggestions or know what the root cause could be? Why is the effects loop in the 5153 generating so much noise when I use my pedalboard's power supply, but not getting any when I use the same power supply with my 6505. But when I use the power supply my EQ pedal came with, I get a lot less noise with the 5153.
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#2
If you bridge the send to the return of the EVH amp with a 1/4 cable, do you get noise? 

I've had similar phantom noise problem, in my case was dirty pedal power and a digital delay pedal (DD3) that was leaking some clocking chirps. I put the digital delay on its own power supply, problem fixed. Also bought a power conditioner which before I moved the DD3 diminished the noise somewhat. 

The only thing that I can think of in your case is either one of the digital pedals is not liking your power supply or the power supply's traff is somehow leaking into the audio side of the pedals. 

Did you also try different pedal cables? Just to test it out, take the ground out on a cable if you can and put that as last right before the fx return. 
#3
Quote by diabolical
If you bridge the send to the return of the EVH amp with a 1/4 cable, do you get noise? 

No. I get silence.
I've had similar phantom noise problem, in my case was dirty pedal power and a digital delay pedal (DD3) that was leaking some clocking chirps. I put the digital delay on its own power supply, problem fixed. Also bought a power conditioner which before I moved the DD3 diminished the noise somewhat. 

I've been considering if it is just a dirty power supply, but if that were true, then why does my 6505 not have this noise problem under the same conditions?

I want to know for sure if it is the power supply causing this problem before I spend the better part of £150 on a new isolated power supply, having just spent £1000 on an amp.
The only thing that I can think of in your case is either one of the digital pedals is not liking your power supply or the power supply's traff is somehow leaking into the audio side of the pedals.

The volume and the tone of the noise is exactly the same regardless of what pedal I use in the loop. Analog, digital, it doesn't make a difference.
Did you also try different pedal cables? Just to test it out, take the ground out on a cable if you can and put that as last right before the fx return. 

I've effectively done the same test by measuring the resistance between the output of the last pedal in the chain to the input of the first one. I get 0 ohms.
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#4
Power conditioner? Different wall/room plug test?

Were these amps fx loops tube controlled? Maybe noisy tube. See what tube it is and swap position with another or replace.

Did you try removing ground on the last analog cable that goes to fx return?

Maybe try cheap fix:
https://www.amazon.com/one-spot-pedal-power/s?ie=UTF8&page=1&rh=i%3Aaps%2Ck%3Aone%20spot%20pedal%20power

It might be time to talk to the EVH amp support, ask what they think?
#6
Right, I did many hours of experimentation with my pedalboard and a multimeter and the long and the short of it is, it looks like the design of the amplifier is such that the effects loop ground is not actually ground.

On the Schematic of the 5153, there is a 10K resistor between the ground of the send on the effects loop and the ground on the return of the effects loop. This is causing the grounds between the send and return of the loop to be floating. You want all the grounds on an amp to be common grounds wherever possible. But it seems like Fender made a conscious effort not to make the grounds on the send and return common. Why Fender designed the amp like this truly bewilders me.

This would be okay if all the pedals on my board were also fully grounded. Any noise that came through the effects loop would be grounded through the pedal. However, not all the casings of the pedals (due to the plastic insulation on the input and output jacks), are grounded. One of the ones that is grounded to the case through the power supply is my 10-band EQ. This causes the floating ground in the effects loop to put noise through my power supply via my EQ pedal, which feeds back into my power supply, and because my power supply isn't fully isolated, it feeds that noise into all my other pedals. Thus creating all the noise I am hearing.

Basically, what I am trying to explain is why I need an isolated power supply that costs a fuckton of money to fix the issue. Either that or I need to take the amp out of its chassis, and snip that 10K resistor between the send and the return of the effects loop, so that the grounds between the 2 are all common.
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#7
Sorry to hear that...maybe it is something to do with long runs, or maybe flow in case of an el. shock live, hoping to break the chain at the amp, so it will blow, instead of say a moist pedalboard on stage at the Isle of Wight.

It says made in Mexico on the back of the amp, doesn't it? That should explain everything! At least in Texas it does
#8
I've decided to purchase an MXR DC iso brick. The M238. I need such a power supply as I run so many pedals and unlike the original MXR DC brick, which is basically just a glorified, overpriced daisy chain, this one actually is fully isolated. That'll be £147.

Why are isolated power supplies so friggin expensive.

I also wish manufacturers were clear on what they define as being 'isolated'. MXR insist that iso brick does actually have individual transformers for each output, so it is indeed isolated like it claims to be. But some cheaper supplies claim to be 'isolated', but the only thing that's isolated about them is that the supply comes with overload circuit protection such that it disables an output if it gets overloaded, without taking out all the other pedals, thus "isolating" (in massive quotation marks) that troubled output from all the other pedals. But this is not what 'isolated' in the context of pedalboard power supplies means at all.

It was only when I opened up my old power supply that I discovered that this is how the manufacturer got away with claiming their supply was 'isolated': Pure marketing bullshit designed to mislead consumers.

Basically, don't trust the manufacturer. I'll believe the MXR is isolated when I open it up and see inside it with my own two eyes.
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#9
^ yeah definitely, agreed 100%.

there are a few cheaper isolated ones (the harley benton power plant junior and the musicstore/fame clone of the voodoo labs one) but i'm not sure how well they're built... a couple of the HB ones went faulty on me, for example (i haven't tried the musicstore one but have had bad experiences dealing with them in the past).
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#10
Just for people's reference in the future, my MXR ISO brick arrived in the mail today and has completely fixed this issue. The ISO brick's outputs are indeed fully isolated as advertised and my pedals are nice and quiet now.


Lesson Learned: For anyone thinking of buying an EVH 5153, if you do not have a fully isolated power supply for your pedalboard, you'll need to add one to the total price tag of the amp if you want to use any of your pedals in the loop.

You cannot get away with just using a daisy chain or a non-iso box with this amp. The ground loop it generates makes the effects loop useless. It isn't something you should necessarily have to buy, but once you get one, the problem completely goes away.
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#11
^ Couldn't you just use two separate cheaper PSUs- one for the front of the amp, and one for the pedals in the loop? That might be more bother than it's worth, though.

But glad you got it fixed.
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Quote by K33nbl4d3
I'll have to put the Classic T models on my to-try list. Shame the finish options there are Anachronism Gold, Nuclear Waste and Aged Clown, because in principle the plaintop is right up my alley.

Quote by K33nbl4d3
Presumably because the CCF (Combined Corksniffing Forces) of MLP and Gibson forums would rise up against them, plunging the land into war.

Quote by T00DEEPBLUE
Et tu, br00tz?
#12
Quote by Dave_Mc
^ Couldn't you just use two separate cheaper PSUs- one for the front of the amp, and one for the pedals in the loop?

No. I have tested this scenario as well.

The pedals in the front of the amp don't have to be isolated for the amp to work okay, but if you're using any more than 1 pedal in the loop, the power supply for that loop must be fully isolated.
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#13
Oh ok. Wow.

That's definitely a useful thing to flag up, then, since these amps seem pretty popular.
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Quote by K33nbl4d3
I'll have to put the Classic T models on my to-try list. Shame the finish options there are Anachronism Gold, Nuclear Waste and Aged Clown, because in principle the plaintop is right up my alley.

Quote by K33nbl4d3
Presumably because the CCF (Combined Corksniffing Forces) of MLP and Gibson forums would rise up against them, plunging the land into war.

Quote by T00DEEPBLUE
Et tu, br00tz?
Last edited by Dave_Mc at Mar 10, 2017,
#14
Yeah, sucks doesn't it?

In any case, an iso power supply is a good piece of gear to have anyway.

I am somewhat hesitant to suggest this to anyone who owns this amp because they might not necessarily run into the same problem that I did, but if people run into a noisy effects loop with this amp, then getting an iso power supply is likely the solution.
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#15
Yeah definitely.

I guess I was just sort of thinking out loud. It's a bit like the true bypass/buffer thing, these things seem to lurch from one extreme to the other. For a while there, isolated supplies were all the rage... then some people started suggesting that you might actually not need them... and then it almost got like you were silly if you had one, that you'd been suckered by fancy advertising and marketing. So it's interesting that you've found at least one verified situation where you very much do actually need one.
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Quote by K33nbl4d3
I'll have to put the Classic T models on my to-try list. Shame the finish options there are Anachronism Gold, Nuclear Waste and Aged Clown, because in principle the plaintop is right up my alley.

Quote by K33nbl4d3
Presumably because the CCF (Combined Corksniffing Forces) of MLP and Gibson forums would rise up against them, plunging the land into war.

Quote by T00DEEPBLUE
Et tu, br00tz?