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Pedal Power Supply Advice Needed from any Gurus!


Ashwood1985
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Hi y'all,

I can't find this question in an existing thread so forgive me if it's been dealt with before.

Basically I currently use two non-brand 9v 1A supplies to power my 9v stuff and independent supplies for my Markbass Compressore at 15v and my DHA VT1 ar 12v.

After some experimentation, I've managed to find a certain configuration of daisy chaining that gets the mid-range whine that's plaguing the set up to a bare minimum, so this is a reasonably minor issue as I have an ISP decimator on the way.

[b]The main problem is that the VT1 when powered separately is very quiet except the hiss you'd expect from the tube when driven. BUT when it's on the board with all the 9v pedals it buzzes like a chainsaw when engaged.[/b]

So here's the question: If I get a Diago powertrain and run all my 9v stuff off this instead of the generic supplies I'm using now, will this eliminate the interference the VT1's supply is getting? i.e. is this happening because the chains are running from PSUs that aren't filtered very well and the diago would sort it? Or do I need to go the whole hog and get something that provides isolated outs for everything like the Voodoo 4x4 to power all but the markbass (15v)? If money was no object I'd do this in a heartbeat but the things are £180!!! :-/

Here's my current set-up for your reference:

TU3 -> MB Comp -> Boss GE7B -> RC booster -> OC-2 -> VT1 -> EBS Chorus -> EHX SMMH -> Morley MiniVolume

Also I plan on whacking in another Boss EQ, LS-2 and ISP Decimator soon so thats 3 more 9v pedals.

Power chain 1 - (TU3, Boss GE7B, RC Booster, OC-2, EBS Chorus)
Power chain 2 - (EHX SMMH, Morley MiniVolume)
VT1 - independent 12v wall wart
Markbass Comp - independent 15v wall wart

Cheers in advance dudes for reading this and any info/thoughts/experience you may share,

Ash :)

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OK, my first guess is that the buffer circuit in the MM is dealing with the buzzing (probably a ground loop) and that's why it goes away. It sounds like the 2 9V supplies are good, since they (mostly) play alongside each other, so likely that the problem is the current 12V supply you're using. A possible solution would be to find a buffer pedal (or a cheap pedal with a suitable buffer in it) that can be incorporated in the rig to silence the buzz, though a better solution would be to replace the dirty power supply (assuming it's not caused by the VT1 itself).

But I'm no guru

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Cheers for the response mate,

My first thought is the fact that the MM isn't true bypass. So isn't the buffer active even when bypassed? No doubt you're right about the principle but I'm a llttle confused as to why it doesn't occur while bypassed for this reason (approaching circuit territory!) :blink:

Anyway I've arranged a diago powerstation through a BCer in order to stabalise things further with all the 9v stuff. I do plan on putting the VT1 in one of the LS2's loops with a second boss eq in order to dial back in some little highs or whatever into the VT1's signal so from what your saying, if I leave that on for the time being until (just flatten in out rather than bypass it hopefully it should kill it until I can sot a more permenant solution.

As much as I might fancy a voodoo 4x4 for all but the MarkBass, £180 can be used much more wisely for me right now if I can get a clean board on a budget :)

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[quote name='simwells' timestamp='1357118351' post='1917574']
When I had a VT1 I always found it needed an isolated supply to keep noise free so either some form of isolator or it's own power supply.
[/quote]

Yeah it does have it's own supply, and it's fine sitting away from the board! It's when its sitting near or on the board with the other pedals powered with the 9v daisies that it misbehaves.

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[quote name='Ashwood1985' timestamp='1357118628' post='1917577']
Yeah it does have it's own supply, and it's fine sitting away from the board! It's when its sitting near or on the board with the other pedals powered with the 9v daisies that it misbehaves.
[/quote]

poor ground by the sounds of it, check your cables.

failing that I have seen once before some digital pedals causing problems. Try adding a pedal at a time to the board and see if which one is to blame.

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[quote name='DHA' timestamp='1357134843' post='1917878']
poor ground by the sounds of it, check your cables.

failing that I have seen once before some digital pedals causing problems. Try adding a pedal at a time to the board and see if which one is to blame.
[/quote]

Thanks Dave!! Awesome work btw dude! :D

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I use a separate supply for my VT1EQ. I [i]can[/i] run it daisy chained from my one spot (with an inverter), but that's only 9v. The only time I've had 'buzz' issues was with a digital pedal (EHX Freeze), so I used the 9v feed from a Boss TU3 and that sorted it; must be them magic buffers...

I find that old style 'transformer' supplies are cleaner than newer 'switch mode' ones, but that's just me.

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[quote name='paul_5' timestamp='1357142780' post='1918047']
I use a separate supply for my VT1EQ. I [i]can[/i] run it daisy chained from my one spot (with an inverter), but that's only 9v. The only time I've had 'buzz' issues was with a digital pedal (EHX Freeze), so I used the 9v feed from a Boss TU3 and that sorted it; must be them magic buffers...

I find that old style 'transformer' supplies are cleaner than newer 'switch mode' ones, but that's just me.
[/quote]

this is the problem I have seen before. Don't fully understand it but there seems to be a reaction between some digital pedals and soundcards and the Vt1's switchmode power supply or the Vt1's very wide bandwidth. Must be something to do with the digital sampling rate which is way outside of most pedals frequency range but valves have a huge bandwidth which I keep as wide as possible to keep the bass and treble response. Most of it you can't hear but these high and low frequency harmonics have an effect on the tones "fat" sound, just makes it sound richer.

the good news is that it can be fixed either with buffers, moving pedals around a bit in the chain and/or power supplies.

Dave

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[quote name='DHA' timestamp='1357201597' post='1918904']
Most of it you can't hear but these high and low frequency harmonics have an effect on the tones "fat" sound, just makes it sound [s]richer[/s] frickin' awesome.
[/quote]

Fixed ;)

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[quote name='Ashwood1985' timestamp='1357165603' post='1918649']
(DUDE! I just noticed your R2D2 mug avatar! Already googled it and will probably order the bleepin little bad boy! Gas for robotic china :gas: ha!)
[/quote]

'twas my 'BC secret santa' virtual christmas present.

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