GT-830

Big, fat bottom with wide range of drive from cleanish boost to hair metal

The GT-830 overdrive rack effect module compares to the Maxon DS-830 Distortion Master. Perhaps lesser-known in the USA, the DS-830 has an active tone stack focused on a big, tight low-end tone, with drive levels from cleanish boost to overdrive and into distortion.

Description

For some reason, there are a few great Maxon effects that players in the USA may have missed. The DS-830 Distortion Master is one of them. The GT-830 compares to this largely undiscovered pedal. The individual sections of the circuit are generally unremarkable in design, including input and output buffers and silicon diodes in both hard and soft clipping configurations. But there is a unique active tone section providing independent Bass and Treble controls with a wide range of effect. The overall tone purposely highlights the low end, and tends to be a little warm and dark, especially when the Gain is low. It is meant to provide a solid bottom and some fat. The Gain provides a wide range, from almost clean, through overdrive, and into distortion. With the GT More Gain option, the Gain range extends well into hair metal tones, with plenty of touch, feedback, and harmonics. The Gain cleans up pretty well with the guitar volume, but don’t expect pristine cleans at any settings. The gain is enough to hit the front end of your amp or downstream pedals pretty hard, enabling amp break-up or meltdown, should you choose it. The character of the gain is somewhat Marshall-like, although clipping diode selection can change it up.

Since it is designed to fatten up the tone and provide a nice tight bottom, the circuit can sound dark, particularly with humbuckers. The wide range of the active tone control will counter that, but even the tone stack is purposely skewed a little to provide more control over the lows than highs. The stock silicon clipping diodes are good, but red LEDs and no clipping diodes at all both yield brighter tones, although the character of the distortion also changes. In other words, clipping options are worth considering, maybe even more so for humbuckers than single coils. If you already have a bass-heavy tone, this may give you some good shaping options or push you into the Dark Side. If your tone is a bit thin or bright, this can give you some nice bottom end to round things out a bit.

Configurations

GT-830 - compares to Maxon DS-830 Distortion Master

Options

More Gain - This option extends the range of distortion at the top end. The standard Gain control gets you a bit past overdrive levels toward distortion. The More Gain option will get you up into the hair metal range, with plentiful feedback, harmonics, and touch sensitivity, similar to a high-gain amp. This is a good option if you like having a wide range of Gain flexibility.
Custom Clipping Diodes and Switched Clipping - The circuit has soft clipping diodes followed by hard clipping diodes. The standard configuration is symmetric silicon 1N914 diodes in both clipping sections. This is a little odd, as the two sections clip to the same voltage, meaning the second clipping section (hard clipping) doesn't do that much. But it sounds good, nonetheless. Of course, we like clipping options, so we provide them in both sections, with the same capabilities. Each section provides the ability to have two clipping configurations. Each config can have up to 4 diodes, a pair in each direction. Or singles in each direction. Or an asymmetric config of 1 and 2. You can stick with a single configuration of your choice for both hard and soft clipping, without switching. Or you can put in a second config for either/both of hard and soft clipping and switch between them. With a 3-way switch, we can give you a third option of no diodes for either/both sections. You can switch your soft clipping diodes with your hard clipping diodes on a single switch or switch them separately with two switches. There are a couple of things to consider when selecting your diodes. Germanium (Ge) diodes clip at the lowest voltage, then Silicon (Si), then LEDs at the highest voltage. The soft clipping comes before the hard clipping. If you put a low voltage diode in soft clipping and a higher voltage diode in the hard clipping, you won't get much hard clipping. If you put a high voltage in the soft clipping then a lower voltage in the hard clipping, you'll get mostly hard clipping. The circuit is designed to use the same type of diodes in both locations to give the clipping the flavor of the selected diode. We recommend switching your hard and soft diodes together, and that they be the same type. As an example, switch between Si diodes in both positions to LEDs in both positions. Ge diodes with reduce the volume considerably and may make a circuit that already has plenty of lows too dark. The Gain will also be reduced. We don't recommend Ge diodes for this one. The "no diodes" switching option is pretty good. There is still plenty of distortion, plus you get a little more volume. If you want clipping options, we recommend a Si/Si option, No Diodes in the middle position, and red LEDs/red LEDs. We generally choose symmetric, 1 diode each direction, but if you like asymmetric, go for it. The pricing is divided between diodes and switches. Your can have no switches (single hard and soft clipping configs), 1 switch (switches either hard or soft or both together), or 2 switches to switch hard and soft separately. The switch can be 2-position to select between two configs, or 3-position to select between two configs and No Diodes. One of your two configs could also be No Diodes. Sounds like a mess? It's actually really easy and we'll help you configure it the way you want. Most common diodes can be selected for no upcharge. Ge or exotics may add a small amount.
Hard Clipping Control - We don't recommend this option unless you are a clipping diode ninja. This control lets you reduce the amount of hard clipping. You won't get much out of this unless your hard clipping diodes clip at a lower voltage than your soft clipping diodes, providing a noticeable level of hard clipping. This might be a good way to add a touch of Ge hard clipping, but as of the time this was written we haven't tried that... yet... If you select this option when your hard and soft clipping diodes are the same, there is very little effect.
Custom Components - The default op amp is the same as the original circuit, a 4558D. These have always been widely used in effects, tending to be a little warm. You can choose any pin-compatible op amp instead, maybe a TL072? The original circuit uses a JFET 2SK246Y input buffer. Those are getting a little difficult to find, so the default config will have a different JFET, probably a 2N5457. This has little, if any, audible impact on the tone, as long as it is a JFET. You can request the 2SK246Y - we try to keep some on hand. The original circuit also uses 2SC1815BL transistors in the tone section and output buffer. These are generic transistors that were once plentiful, but now much less common. Unless you request the 2SC1815BL specifically, we will likely sub a slightly better more available one, perhaps a 2N5088. These transistors have little, if any, audible impact on the tone. We use metal film resistors and a selection of capacitors that provide good tone and low noise.

Front Panel

On/Off indicator LED
Volume
Gain
Bass
Treble
(optional) Hard Clipping control
(optional) 1 or 2 Clipping switches

Rear Panel

Audio In
Audio Out
On/Off Footswitch
On/Off Override
DC Power
DC Power LED

Module Width

1.5" without optional controls or switches
2" with optional controls or switches
2" left wing available for standard configuration
1.5" right wing available for standard configuration

Power Consumption (aprox)

15mA

Base Configurations

Part #	Description	List Price
MOD-GT830	GT-830 module	$225

Options

Part #	Description	List Price
MOPT-GT830-GAIN	More Gain	$0
MOPT-GT830-CLIP	Custom Clipping Diodes	$0 - TBD
MOPT-GT830-SWCLIP	Clipping Diode Switch(es)	$19 - TBD
MOPT-GT830-HCLIP	Hard Clipping Control	$19
MOPT-GT830-CC	Component Changes	TBD