Hermida Zen Drive 2: Does the valve actually do anything?

stonevibe

Just acquired one of these in a trade for some gear, and haven't had a chance to try it yet. Just wondered if the valve in the pedal has much affect on the overall tone? The pedal was thrown in to sweeten the deal and so I haven't given it much attention yet.

I found an old mint Mullard ECC83 recently, which I have sat spare, so was contemplating doing an A/B when I have some spare time to get around to it. Just figured I would ask the collective wisdom of the forum before I start tinkering with it.

robinbowes

Used for clipping instead of diodes.

stonevibe

Cheers fella, I'll take a proper look at that 

ICBM

Configured as a dual diode... brings an oddly inverted meaning to the term 'diode clipping' .

This is actually only the second example I know of with a valve used like this - the other is the Fender Performer/Roc Pro amp.

I doubt the differences between different valves will have any significant effect on the tone when used like that, but I could be wrong.

stonevibe

ICBM said:

Configured as a dual diode... brings an oddly inverted meaning to the term 'diode clipping' .

This is actually only the second example I know of with a valve used like this - the other is the Fender Performer/Roc Pro amp.

I doubt the differences between different valves will have any significant effect on the tone when used like that, but I could be wrong.

I'm no expert, far from it, but it seems like an odd way to utilise a valve for a drive pedal. 

ICBM

stonevibe said:

I'm no expert, far from it, but it seems like an odd way to utilise a valve for a drive pedal. 

It has the advantage of not needing a high-voltage supply, so it can be simply inserted into the standard pedal circuit. In fact, there's no plate supply at all, it's purely the signal voltage which goes through it. It also has the unusual characteristic that if you remove the valve (or it fails), the output will get significantly louder as well as become clean...!

It's not necessarily as pointless as that sounds though - used as a clipping diode pair, the valve characteristics will determine the onset of clipping, so it's probably going to sound smoother and without that irritating 'separated' solid-state diode effect where the distorted sound seems to sit on top of the clean sound but separate from it, because the clipping is effectively switched on and off as the signal hovers around the threshold of it. The valve should have a very soft onset of clipping and so avoid that.

stonevibe

Interesting, I’ll have to get around to plugging it in at some point.