# NPD : EQD - Plumes



## Ti-Ron (Mar 21, 2007)

Wasn't big on the TS style before. Always had single clean channel amp and the TS wasn't doing it for me. Had a GoudieFX - 808 and a Way Hugues - Green Rhino in the past but didn't understand the appeal.

Fast forward tday, I have a Mesa Boogie Triple Crown and the Plumes is magic in the high gain channels! I didn't explore all the modes yet but sounds good!


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## mhammer (Nov 30, 2007)

Here's the presumed schematic. Several things to note:

A "normal" TS tops out at a gain of 118x, where this one can go up to well over 1000x
A normal TS and SD-1 roll off bass around 720hz; the Plumes rolls off at a little under 1.6khz,but complements this by rolling off treble even more than those two, at both the clipping stage and the tone-control stage.
The modes consist of symmetrical LED clipping, no diodes, and asymmetrical silicon diode clipping, similar to the SD-1 and its predecessor the OD-1.
The plumes uses a charge-pump to produce +/-9v (actually, just under that). I'm not at all clear what advantage this provides to the clipping modes, although it will give more headroom when in the non-clipping booster mode.


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## Ti-Ron (Mar 21, 2007)

mhammer said:


> Here's the presumed schematic. Several things to note:
> 
> A "normal" TS tops out at a gain of 118x, where this one can go up to well over 1000x
> A normal TS and SD-1 roll off bass around 720hz; the Plumes rolls off at a little under 1.6khz,but complements this by rolling off treble even more than those two, at both the clipping stage and the tone-control stage.
> ...


That's cool! Sounds like a super charged TS, isn't.
I always remebered the TS as a honky and brittle od but this one have a fuller sound or my memories is wrong. Latter is possible.


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## mhammer (Nov 30, 2007)

I'll just qualify my comments by noting that this is a reverse-engineered circuit diagram I found posted, not a factory-authorized schematic. There are occasionally errors in such things, though on the face of it, things seem correct. Sometimes you can't even rely on factory schematics. The ones that Maestro published/released in the '70s were chock full of errors. And not intentionally, either. Remember, that would have been when such drawings were for assisting authorized service sites to repair Maestro products. DIY, reverse-engineering, and made-in-China clones wouldn't come along until many years later. These were errors purely resulting from no one checking over things.

I made myself a clone of the first-issue Boss OD-1, that also used asymmetrical clipping, higher possible gain than a TS, and op-amp buffers instead of transistor buffers. So, similar to the Plumes in some ways. Unlike the SD-1, it used a fixed treble-cut filter, with no Tone control. On mine I included a toggle to add more bass than stock, or add both more bass and more treble cut. I like it a lot. Given that the Plumes works a little harder to keep fizz and "brittleness" under control, I can see why folks like it.

Without the augmented supply voltage, it would be difficult to operate it as a clean booster, as it would likely run out of headroom before the Gain control went past 8:00. I have plenty of other clean boosters, so that mode doesn't offer me anything useful, but I can see how it is a very useful add-on for some folks; like getting two pedals for the price of one.


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## Ti-Ron (Mar 21, 2007)

mhammer said:


> I'll just qualify my comments by noting that this is a reverse-engineered circuit diagram I found posted, not a factory-authorized schematic. There are occasionally errors in such things, though on the face of it, things seem correct. Sometimes you can't even rely on factory schematics. The ones that Maestro published/released in the '70s were chock full of errors. And not intentionally, either. Remember, that would have been when such drawings were for assisting authorized service sites to repair Maestro products. DIY, reverse-engineering, and made-in-China clones wouldn't come along until many years later. These were errors purely resulting from no one checking over things.


No worries, I am not quoting you for my research papers and I really appreciate your input! 



mhammer said:


> I made myself a clone of the first-issue Boss OD-1, that also used asymmetrical clipping, higher possible gain than a TS, and op-amp buffers instead of transistor buffers. So, similar to the Plumes in some ways. Unlike the SD-1, it used a fixed treble-cut filter, with no Tone control. On mine I included a toggle to add more bass than stock, or add both more bass and more treble cut. I like it a lot. Given that the Plumes works a little harder to keep fizz and "brittleness" under control, I can see why folks like it.
> 
> Without the augmented supply voltage, it would be difficult to operate it as a clean booster, as it would likely run out of headroom before the Gain control went past 8:00. I have plenty of other clean boosters, so that mode doesn't offer me anything useful, but I can see how it is a very useful add-on for some folks; like getting two pedals for the price of one.


This is exacly why I bought this pedal. I can have a couple of usefull things out of it without too much money (150$ cad shipped).
Here's the rundown of the 3 clipping options:



> *1. Symmetrical LED clipping -* More Crunch and Compression.
> *2. No clipping -* Wide open OpAmp drive for clean boost.
> *3. Asymmetrical silicon diode clipping -* More transparency with a loose feel.


Is the "no clipping" option is a way to bypass the headroom problem of the circuit?


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## Davidian (Sep 8, 2008)

I purchased one recently as well from a fellow forum member, and I think it's a fantastic pedal to boost my already lightly driven JCM800. I A/Bed it with my trusty basic Boss SD-1 and here are my thoughts...

Symmetrical clipping (left toggle) mode gives a nice crunchy drive at lower/practice levels. Perfect for that GnR type/Izzy Stradlin rhythm riffing. Very close with the SD1 but more gain, more bass and less mid bump
No clipping mode (middle toggle) has a very airy, open drive sound, think AC/DC.
Asymmetrical mode (right toggle) has a slight mid bump in the mids, less drive
the tone control is calibrated really well in that the whole sweep is useful
slight noisier than my SD-1
Overall, it's very dynamic and touch responsive more than my SD1. It is however, looser in the bass in any of the 3 modes compared to the Boss, and has less mid hump. I am looking forward to trying it in a band situation to see how it sits in the mix.


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## mhammer (Nov 30, 2007)

It doesn't bypass it so much as make productive use of it. Remember that most op-amps can only "swing" to within a volt or two of their "rails". So, with a 9V power supply, a typical op-amp could produce an output of a volt or more less than that; specifically a maximum of maybe +/-3 to 3.5V. Given that the initial peak produced by hitting a power chord on a humbucker-equipped guitar might exceed 1volt, before settling back down to 250mv or less, how many times can you "fit" 1volt into 7? Not very much. By increasing the power supply to +/-9V (i.e., 18V, rail-to-rail) the clean headroom of the op-amp is increased. You will still run out of headroom and make the chip distort if the gain is set too high; after all, a maximum gain of >1000x is going to run out of headroom at some point, and the minimum gain is 48x. But at least the "No clipping" mode will let you turn the gain up past 7:00 a bit, before the chip starts to distort.

And to add to Davidian's point about the tone control, a TS-9's tone control provides a 5.5x boost for upper mids and treble (content above 3.3khz) when fully clockwise, where the Plumes reins this back in a bit, and provides a boost of 4x for content above roughly 1khz. So a slightly more modest bark when up full, and so much of a shriek. It's really a very simple mod to do to ant TS-type pedal, but EQD did it.


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