Landgraff mod distortion.

[seljetnoma]

Hi,

With all the talk about the Landgraff Dynamic overdrive, i was wondering if anyone has ever looked inside a Landgraff mod distortion.
I heard that they sound really good, but i wonder on which other distortion pedal it is based on, or if it's an all new original design.
It would be even cooler if someone had a schematic.  :-)

Thanks in advance,

Sel

[nelson]

It is just a tubescreamer clone with clipping diode mods, nothing new or that special. the schematic has been posted to the forum, but you would be worthwhile reading the technology of tubescreamer at geofex.

[seljetnoma]

Hi Nelson,

Thanks for the swift reply.
From your reply i take it that you mean the dynamic overdrive, but the unit i am talking about is the mo-d distortion.
Thanks,

Sel

[spudulike]

Nelson - youre talking about the OD, seljetnoma is talking about the distortion.

AFAIK the mod distortion is a modded RAT.

[nelson]

:oops:  :roll:  :x

[Mark Hammer]

From whatI have seen (and these are reverse-engineered schems, not manufacturer-issued ones), the Landgraff is essentially a "rescaled" Tube Screamer.  

What I mean by rescaled is this.  The TS-9 anticipates a certain input signal level.  It provides a certain amount of gain, and sets a certain clipping threshold to complement that.  As it turns out, because of the mannerin which people tend to pick, the guitar output signal resulting from this, and the fairly modest clipping threshold, the sound tends to be fairly compressed because it is too easy for typical picking to result in a threshold-level signal.

The Landgraff mods provide a much higher clipping threshold and additional gain to supplement/complement that.  If the gain is set modestly, you can pick your brains out, and achieve considerable volume without necessarily hitting the clipping threshold all that often.  People describe this as being more dynamically responsive.  You could probably do it with a TS, simply by turning the guitar volume down, but obviously the "push" that the pedal provides the amp's input section would be absent, and any noise/hum acquired along the guitar cord would be all that more noticeable.

There are a few other things that I think are different (don't have the schem with me at the moment), and I may have missed something, but that's the main difference from what I can see.

[cd]

Nice little treatise Mark, but it's still the wrong pedal you're talking about  What the original poster is inquiring about is the MO'D, which indeed is a slightly modded RAT.  How is it modded?  Take what you know about the Dynamic Overdrive and apply it to the RAT.  Problem solved.

[Khas Evets]

There are two main differences.

1. Switching between two LED's (symmetrical) or three 1N914's (asymmetrical like SD-1).

2. Changing the 4.7K resistor and .0047uF cap in the feedback loop to 1K and .22uF.

What Mark said is correct (as usual), but I believe it only applies to the LED mode with an increased clipping threshold. When using silicon diodes, this pedal will have similar picking sensitivity as an SD-1 with added gain as a result of #2 above.

[cd]

There are two main differences.

1. Switching between two LED's (symmetrical) or three 1N914's (asymmetrical like SD-1).

2. Changing the 4.7K resistor and .0047uF cap in the feedback loop to 1K and .22uF.

What Mark said is correct (as usual), but I believe it only applies to the LED mode with an increased clipping threshold. When using silicon diodes, this pedal will have similar picking sensitivity as an SD-1 with added gain as a result of #2 above.

Again, wrong pedal.  To clarify, that's the Dynamic Overdrive, not the MO'D.  And it should be 4k7 and .047u (47nF) from the - input to ground, not in the feedback loop.  FYI the 1k and .22u combination does not change the frequency response (same TS bass loss) but it does increase the distortion range (more drive available).

Also remember that almost half of the components (and virtually all of the ones that affect frequency response) in the DO are socketed.  Meaning with the additional $ "tone kit" you can change the tone of the pedal to your heart's content (and indeed, many are tweaked for specific players).  The standard "made for Blues Angel" model is the one in the widely circulated schematic.  The socketed components are:

- every capacitor EXCEPT for the power filtering caps and the cap on the tone pot wiper
- resistors on - input (pin 2) of first gain stage (1k and 10k)
- clipping diodes (including the "no clipping diodes" selection)
- both transistors

[Khas Evets]

Sorry, I should have read more carefully. :oops:

[seljetnoma]

lol, no problen guys, thanks anyway, i saw the other Landgraff topic and wondered ( still do ) about their distortion unit.

Take care,

Sel