Frequently Asked Questions

Soldering Tips

Click here for a PDF with tips on proper soldering.

The Trill Tremolo

Where can I find troubleshooting help for the Trill Tremolo?

Click here for troubleshooting tips for the Trill Tremolo.

Can I add an LED to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic with part numbers indicated.
LED Add Schematic

Can I add a Power Jack to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic along with a modified layout drawing of the Thunderdrive Deluxe.
DC Power Jack Add (Thunderdrive Deluxe Layout)

The 1ML depth control doesn't seem to reduce the intensity of the effect very much, is there a fix for this?

Yes. We have provided a schematic showing how to connect a 1MA pot acting as a variable voltage divider (instead of a 1ML pot acting as a variable resistor) for a more dramatic "intensity" control effect.
Trill Intensity Modification

The Rattler

What are the effects of the different value capacitors included with the Rattler kit?

The optional capacitors allow you to modify the high pass filter in the circuit. A greater value of capacitance will allow more low frequencies to pass, while a smaller value will block more of the lower frequencies.

Can I add an LED to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic with part numbers indicated.
LED Add Schematic

Can I add a Power Jack to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic along with a modified layout drawing of the Thunderdrive Deluxe.
DC Power Jack Add (Thunderdrive Deluxe Layout)

MOD 101 Guitar Amp Kit

What tools do I need for the MOD 101 guitar amp kit?

You will need the following tools:

  • Wire Strippers
  • Needle Nose Pliers
  • Cutting Pliers
  • Desoldering Pump
  • Solder (60/40 rosin core)
  • Soldering Station
  • Phillips Head Screwdrivers
  • Slotted tip screwdrivers (3mm tip)
  • Digital Multimeter (DMM)
  • Alligator Clip Test Leads (to fit DMM)
  • Channellock Pliers (or similar type)
  • Miniature Round File (fine cut)
I live in the UK, does the power transformer for the Mod 101 work for 220V, 50Hz?

This amp kit uses a Hammond Manufacturing "300" Series world power transformer. It can be wired for the various voltages used around the world.While the instructions are only written for United States wiring (120V, 60Hz), you may be able to figure out the wiring for your country.

Do you recommend the product called a "yellow jacket" that installs in the tube base, allowing for interchanging of the tubes in the Mod 101?

The Yellow Jackets YJS (normal or triode) model is the correct tube adapter to use with the MOD 101. Using Yellow Jackets in your MOD 101 will allow you to use EL84 power tubes in place of the 6L6GCs or EL34s. They will also reduce the maximum output power from 60 watts to between 18 and 30 watts (YJS normal) and to between 6 and 18 watts (YJS triode).Because Yellow Jackets convert the power stage to Class A auto-bias configuration, you do not need to change the amp\'s bias pot when using the Yellow Jackets.

What is the difference in sound between using 6L6GC or EL34 Power Tubes?

Generally, the EL34s will allow for a little easier breakup than the 6L6GCs and they will have a tighter more straight-forward low and mid body. Of course, each power tube brand and type will bring its own personality to the mix. We highly recommend trying different brands and types of tubes to find your favorite.

Why did you design the Mod 101 amp to be able to get so loud?

The 60 watts of power output can really come in handy when playing in a large impromptu jam session or at a gig with limited PA capabilities. But at low volume or with the use of a power attenuator, the amp will still sound excellent at levels that will not drive your neighbors crazy.

Why are there no internal effects or channel switching features in the Mod 101?

The amp was designed to be basic and classic allowing for warm clean tone at low volume and transitioning gradually into rich power tube overdrive distortion at higher volume, while encouraging the builder to experiment with basic circuit variations to find their preferred tone. Many amp builders and guitar players have found that the quality of tone is degraded more and more with the addition of internal effects and channel switching. (Also, more effects and more tubes make the amp more of a workout to carry around.)

What kind of chassis comes with the Mod 101?

The kit comes with a black powder coated steel chassis which is pre-punched. Because the steel is punched before being coated, you will need to file away the coating around the holes to allow for conductivity between connections made to chassis ground. (This is a step included in the instructions).

What brand of transformers does the Mod 101 use?

The kit comes with Hammond Transformers 374BX and 1650P.

Is there an FX loop in the Mod 101?

There is no FX loop, but the amp sounds great with effects pedals.

What is the output impedance of the Mod 101?

The kit comes with a rotary impedance switch allowing you to change the output impedance to 4, 8, 16, or 20 ohms. This gives you the flexibility to use different speaker configurations and not waste output power or damage the amp.

How is the Mod 101 biased?

The power amp is fixed biased for Class AB operation with an adjustable bias pot. (The instructions will guide you through setting the bias for both 6L6GC and EL34 power tubes).

Are all the parts provided for the 32 different circuit variations in the Mod 101?

Yes, all the parts are included for the different circuit variations.

Does the Mod 101 have a tube or solid-state rectifier circuit?

The Mod 101 has a solid-state rectifier.

Is there an explanation somewhere detailing the 32 circuit variations of the Mod 101and what they do?

Yes, the last section of the instructions gives details on the modifications which can be implemented by using the included extra components. The following is a list of the modifications:

  • Tone Stack Mod
  • Input Voltage Divider Mod
  • Negative Feedback Mod
  • Bypass Cap Mod
  • Power Tube Mod
In the Mod 101, is it possible to change between the matched pairs of EL34 and 6L6GC power tubes without having to de-solder or change out any other components?

Yes, if you follow the EL34 set up initially, then you can switch to 6L6GC tubes without changing any other components. It\'s always a good idea to check the bias when changing power tubes. (The bias can be checked and adjusted with just the steel cage removed and using a volt meter - the instructions will explain this process.)

Can the Mod 101 be modified for cathode biasing instead of fixed?

No, the instructions do not explain a modification for changing the power tubes from fixed bias to cathode bias.

Can other preamp tubes be used in the Mod 101?

Yes, other preamp tubes may be used in place of the 12AX7 in position V1. (For example: ECC803, 12AT7 and 12AU7).

Can the Mod 101 be built with a tube rectifier? If so do you provide instructions?

No, the instructions do not explain a modification for changing from full wave solid state rectification to tube rectification. (Although, the Hammond 374BX power transformer does come with an extra secondary winding not used in the kit).

Can the Mod 101 use other power tubes other than 6L6GCs and EL34s?

Yes, you can use the following power tubes which are substitutes for 6L6GCs and EL34s

  • 6L6GC substitutions: 5881 and KT66
  • EL34/6CA7 substitutions: KT88 and KT77
My pilot light does not turn on, what could be causing this?

Check the fuse. It has probably blown do to excessive current draw. A blown fuse measures as an open circuit from end to end and usually happens when something else in the circuit is wrong. The fuse is a protective device, so if your fuse has blown, check your work to see what may have gone wrong.

What does it mean if I'm hearing a very loud low frequency hum when I turn my Mod 101 on?

A low 60 Hz hum can be the result of:

1)The power transformer\'s filament winding center tap (TR1 green/yellow wire) has come loose.
-Check to make sure this wire is connected properly and not just hanging on by a cold solder joint.

2)You may have a faulty tube in V1. Sometimes a bad preamp tube will amplify the filament's AC frequency.
-Remove the tube in V1 (ECC83) to see if the hum goes away.

Is it possible to add a master volume control to the MOD 101?

Yes. The parts are not included with the kit, but we have provided a schematic and layout drawing for how to add a "post phase-inverter master volume" (PPIMV) control in the MOD 101 "File Downloads" section.

Mod 101 PPI-Master Volume Mod Instructions

My MOD 101 still has some sound with volume at "0" and with all controls at "10" it's motor-boating. Is there a fix for this?

Yes. This is most likely due to the shared cathode of the V1 preamp tube. The parts are not included with the kit, but you can easily split up the cathodes by using the instructions provided in the MOD 101 "File Downloads" section.

Mod 101 Shared Cathode Split Mod

The Wahtz Wah

Can I add an LED to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic with part numbers indicated.
LED Add Schematic

The Ring Resonator

Can I add an LED to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic with part numbers indicated.
LED Add Schematic

Tea Philter

Can I add an LED to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic with part numbers indicated.
LED Add Schematic

The Thunderdrive

Can I add an LED to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic with part numbers indicated.
LED Add Schematic

Can I add a Power Jack to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic along with a modified layout drawing of the Thunderdrive Deluxe.
DC Power Jack Add (Thunderdrive Deluxe Layout)

The Thunderdrive Deluxe

Can I add a Power Jack to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic along with a modified layout drawing of the Thunderdrive Deluxe.
DC Power Jack Add (Thunderdrive Deluxe Layout)

The Persuader

Can I add an LED to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic with part numbers indicated.
LED Add Schematic

The Piledriver

Can I add an LED to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic with part numbers indicated.
LED Add Schematic

Can I add a Power Jack to this Pedal?

Yes. The parts are not included with the kit, but we have provided a schematic along with a modified layout drawing of the Thunderdrive Deluxe.
DC Power Jack Add (Thunderdrive Deluxe Layout)

The pot sounds scratchy when I turn the knob, is there a fix for this?

Yes. The pot in the Piledriver circuit has a DC voltage across its terminals and this makes the pot sound "scratchy" when you turn the knob. We have provided a schematic showing how to isolate the pot from DC voltage by adding a 47uF cap and 1.5K resistor at the MOSFET source terminal.
Piledriver Scratch-less Gain Pot Mod Schematic

MOD 102 Guitar Amp Kit

Can the MOD 102 power transformer be wired to work with any wall voltage in the world?

No. It comes with the Hammond Mfg 269EX power transformer which is only designed for 120V wall outlets (USA). Hammond does sell a 369EX version which has primary winding options to work with any wall voltage in the world, but it would require you to drill new mounting holes and determine which primary winding wires to connect for your country. We have provided a chassis hole modification drawing which offers a suggestion for how to accommodate the slightly larger footprint of the 369EX.

The MOD 102 cannot be ordered to include a 369EX in place of the 269EX.
World Power Transformer Mod 369EX

Can I add a standby switch to my MOD 102?

Yes. If you find it necessary to have a standby switch, we have provided a layout drawing and schematic for how to replace the SPST power switch with a 3 position progressive toggle switch to control both power and standby with one switch.
Power + Standby Switch Modification

Can I add a headphone jack to my MOD 102?

Yes. We have provided a schematic for how to add a headphone jack to the output of the MOD 102.
Headphone Jack Mod Schematic